Category Archives: B cell lymphomas

Updates from #CowenHealthCare 2020 – CAR T and it’s competitors

Aleta Biotherapeutics, ALL, AML, B cell lymphoma, B cell lymphomas, biologics, BITE bi-specific, cancer, CAR T, CAR T cells, Chimeric Antigen Receptor, chimeric antigen receptors, CNS pathologies, immunotherapy, leukemia, lymphoblastic leukemia, lymphoma, Lymphomas, Leukemias, Myelomas, myelofibrosis, , , , ,

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If you work in cell therapy you have follow all kinds of therapeutic developments in indications of interest which for us at Aleta Biotherapeutics (www.aletabio.com) includes specific solid tumor indications, and several hematologic malignancies.

Over the last few days we’ve gotten interesting updates regarding diverse hematologic malignancies, including news about therapeutics for front line (newly treated) or relapsed or refractory (r/r) Non-Hodgkin Lymphoma (NHL), multiple myeloma (MM) and acute myeloid leukemia (AML) patients and the myelodysplastic syndromes (MDS). Note here that the reference to different lines of therapy – front line or early line vs r/r, because the treatment paradigms change as patients fail earlier lines of therapy, ie. as they become refractory to or relapse from their current therapy. This can become a long and arduous battle for patients who repeatedly fail treatment. Unfortunately, this is often the case in r/r MM, r/r AML and MDS and in some subtypes of r/r NHL.

On Monday (2 March 2020) I attended the “Cell Therapy & Myeloma” panel at the 40th Annual Cowen Heath Care Conference. This panel covered much more than the title implies, and I really liked the format which is built on the back of questions posed to the audience, to an (unnamed) group of specialists in the field who were polled in advance, and to the seated key opinion leaders (KOLs), in this case Dr Deepu Madduri (Mt Sinai) and Dr Jacob Soumerai (MGH).

They covered a lot of ground.

The first series of questions sought to pin down trends in r/r Follicular lymphoma (FL) a subtype of NHL that can become difficult to treat if patients fail successive lines of treatment. The Leukemia Lymphoma Society has a primer here –https://lymphoma.org/aboutlymphoma/nhl/fl/relapsedfl/.  There has been brisk drug development in r/r NHL including FL. Novel drug classes include CAR-CD19 T cells, bispecific T cell engagers, small molecule drugs (targeting PI3K, Bcl2, BTK, EZH2) and new antibodies. The Cowen panel worked through a series of questions regarding this landscape and there were several key takeaways.

One was the clear preference, by the anonymously polled specialists and by the seated panelists, for CAR-CD19 therapy as the most exciting new drug for r/r FL. The driver here is the durability of response (DOR) in really late line patients and the sense that both overall response rate (ORR) and DOR will only improve as these cell therapeutics move to earlier lines of therapy. It was striking that several classes of bispecific antibodies (the CD3 x CD20 and CD3 x CD19 bispecifics) elicited strong enthusiasm from the audience (mostly analysts and investors) but only muted enthusiasm from the KOLs. This lack of enthusiasm had 2 distinct bases: 1) limited data to date, and 2) “I can give a bispecific after I give a CAR T, but not the other way around”, which was a very interesting thought (and given despite of the few case reports of CD3 x CD20 bispecific therapy working in several relapsed CAR-T patients). I think that in later line patients these clinicians want to keep their options open as long as possible.

Among the other classes of therapeutics, Epizyme’s EZH2 inhibitor tazemetostat received significant support based on the ability to select EZH2-mutated patients, and on good DOR and on good tolerability, the latter thought to be better than the PI3Kdelta class inhibitors, BTK inhibitors or BCl2 inhibition. The consensus was that tazemetostat could see up to 20% market penetration in third line FL after the expected launch in June 2020.

Among the PI3Kdelta inhibitors, Bayer’s copanlisib was singled out as best-in-class with little differentiation among the others (from Gilead, Verastem, MEI, Incyte, or TG Therapeutics). Finally, in this setting of r/r FL, both venetoclax (a Bcl2-inhibitor) and polatuzumab vedotin (a CD79b antibody-drug conjugate), were relegated to minor use by the specialists and panelists.

The uptake of CAR-CD19 therapies has been brisk, and the panelists highlighted quicker payor approvals and the accelerating pace of referrals to cell therapy centers. The consensus is for 30% increase in patient number treated in 2020 (so roughly 1350 patients in the US, vs 1050 treated last year).

The discussion stayed on CAR-CD19 therapeutics to touch on some of the newer trials and entrants. Kite/Gilead is running a Phase III trial of axi-cel (axicabtagene ciloleucel, brand name Yescarta) in second line DLBCL patients vs a standard of care regimen of high dose chemotherapy followed by an autologous stem cell transplant. Data are anticipated in the second half of 2020. The Cowen moderators passed the question: will this trial show a progression free survival (PSF) benefit?  Mind you, this is a low bar since overall survival – the shining triumph of cell therapy – is not part of the question. The audience (again, mainly investors and analysts) was overwhelming positive, giving about 70% odds of a positive impact on PFS. Here the panelists agreed, citing the fact that this trial was enrolling high-risk patients and therefore the comparator arm of the trial (chemo + ASCT) should do very poorly. Success with this trial would move axi-cel up a line of therapy (from 3rd or later to 2nd or later) and bolster the health care value argument that patients may avoid ASCT altogether.  We are apparently already seeing this effect, as a talk at #TCMT20 highlighted the steep decline in transplants being done in DLBCL.

Sticking with axi-cel, this CAR-CD19 cell therapy was highlighted as the one most likely to be the market leader by 2023, based on the (currently) much shorter manufacturing and turnaround time as compared to tisa-cel (tisagenlecleucel from Novartis, brand name Kymriah). The panelists agreed with the specialist poll, despite the fact that they also felt that tisa-cel may be better tolerated by patients overall. Further, the panelists did note that the difference in manufacturing turnaround was likely to diminish as Novartis improves its product workflow. So we’ll have to wait and see.

Competition may also play a role.  The long-awaited Juno > Celgene > BristolMyers Squibb CAR-CD19 liso-cel (lisocabtagene maraleucel) should see its first approval soon, and several allogeneic and non-T cell based programs are advancing. Cowen’s moderators highlighted a number of these for discussion. Allogene CAR-CD19, called ALLO-501 is currently in a Phase 1 trial enrolling r/r diffuse large B cell lymphoma (DLBCL) and r/r FL patients, with initial data expected later this year. The moderators put forward the question: what percent of (responding) patients have to show a durable response for this to be an exciting option to the autologous CAR-CD19 products. It’s a complex question since the current approved CAR-CD19s show about a 50% durable response rate within the responders, where a goodly proportion of the patients that do not have a durable response are relapsing after a response, sometimes with CD19-negative lymphoma or leukemia (ie. the cancer has undergone natural selection and loses target antigen expression). The polled specialists and the panelists wanted to see a pretty high durable response rate, 35-40% (specialists) up to 50% (the panelists). If the field were to see responses as good as axi-cel, tisa-cel and liso-cel, this would be “a huge advance”, according to Dr Soumerai of MGH.

Of note, Allogene itself was a bit more cautious at their public company presentation later in the day. Dr David Chang, Allogene’s CEO, provided some guidance and set expectations. He noted that the company would report early data form the ALLO-501 program at #ASCO20 and/or #EHA20 but stressed the readouts of safety and degree of lymphodepletion from up to 3 dose cohorts, and with several different doses of their lymphodepletion agent ALLO-647, and anti-CD52 antibody. In the ALLO-501 trial this is given along with the lymphodepeleting chemotherapy combination of cyclophosphamide and fludarabine (Cy-Flu). Among the other allogeneic and off-the-shelf CAR-CD19 programs several were highlighted either by the audience (Fate Therapeutics induced CAR-NKs) or the panelists (the Takeda/MD Anderson NK program). Other programs from Atara, CRISPR, and Precision all would have to show some or more data in order to get the specialists or the panelists to take notice.

Notably, there was consensus among the audience, polled specialists and panelists that CD3 x CD20 bispecifics would be less efficacious than CAR T cells, regardless of the specific therapeutics (eg. from Roche or Regeneron or Genmab). Further, Dr Madduri expressed concern at the need to keep dosing patients both because of inconvenience and possible safety over time. Her view is that patients prefer a single dose CAR.

Finally in the r/r DLBCL space, both polled specialists and the panelists saw minimal roles for the anti-CD79b-drug conjugate polatuzumab vedotin (brand name Polivy, from Roche) or the anti-CD19-ADCC competent antibody tafasitamab (from Morphosys, which now has a 30 August PDUFA date with FDA).  Both of these biologics need to be given in combination with other therapeutics and there did not appear to be a benefit over standard combinations. More specifically, polatuzumab vedotin is given with rituximab and bendamustine and was considered “tolerable” but perhaps best used in a bridge to transplantation setting or a bridge to CAR-CD19 cell therapy. Tafasitamab was recently written up by Jabob Plieth here: https://www.evaluate.com/vantage/articles/analysis/why-2020-spotlight-will-fall-tafasitamab.

Turning to r/r MM there were a series of questions about lines of therapy and which were preferred. For newly diagnosed patients and for second-line patients the clearly favored standard of care was an ‘ImID’ (immunomodulatory agent, eg. revlimid) plus the anti-CD38 antibody daratumumab (brand name Darzalex, from Johnson & Johnson’s Janssen division) plus dexamethasone (aka triple therapy) with perhaps a proteasome inhibitor added (thus, a quad). The use of daratumumab in early line therapy will continue to grow as it is payor-approved for early-line use.

For later line therapy, the moderators first brought up selinexor (brand name Xpovio, from Karyopharm Therapeutics), a first-in-class, oral Selective Inhibitor of Nuclear Export (SINE), which was granted accelerated approval last year for use in in combination with dexamethasone for adult r/r MM patients who received at least four prior therapies and whose disease is refractory to at least two proteasome inhibitors, at least two ImIDs, and an anti-CD38 monoclonal antibody. There was a consensus view that this drug will see flat to diminishing use due to poor tolerability. Dr Madduri noted that she gives this drug once week rather than twice a day (as labeled) in an effort to improve patient tolerance and only used it as a bridge to clinical trial enrollment (ie. on something else, for example, CAR-BCMA cellular therapy. Curiously there were no questions about isatuximab-irfc (brand name Sarclisa, from Sanofi-Aventis), newly approved in combination with pomalidomide and dexamethasone for adult patients with r/r/ MM and at least two prior therapies (see this SITC writeup: https://www.sitcancer.org/aboutsitc/press-releases/2020/isatuximab-irfc).

As for CAR T cells for multiple myeloma, the panelists were hesitant to pick a winner between the two advanced CAR-BCMA programs: bb2121 (Bluebird) and JNJ-4528 (from J&J, formally called LCAR-B38M) until J&J updated PFS data. At their public company presentation Nick Leschly, Bluebird’s CEO, noted that they will file the BLA for bb2121 (now called idecabtagene vicleucel or ide-cel) in the first half of this year, and would release longer-term follow-up data from the ide-cel clinical trials KarMMa and CRB-401 in the second half of the year. The BLA will be filed despite the “slow-down” from FDA necessitated by the agency’s request for additional lentivirus production characterization information from their chosen cell suspension manufacturing method (no details given). What the FDA has asked for apparently is both different from and more than the EU agency (EMA) wanted.

On the allogeneic CAR T cell front, Dr Chang at Allogene noted that they would have early data on ALLO-715 (their version of a CAR-BCMA therapy) at #ASH20. Here he noted they are considering dropping the Cy-Flu lymphodepletion and just using their anti-CD52 antibody to lymphodeplete, we’ll see (this doesn’t strike me as realistic).

In general both the polled specialists and the panelists were more enthusiastic about CAR-BCMA therapy than several other modalities, including belantamab mafodotin (from GSK), an antibody-drug conjugate, composed of an anti-BCMA monoclonal antibody bound to auristatin F. This drug was thought to be not quite good enough given the unmet need, there remain concerns about the ocular toxicity (the bane of ADC technology) and keen disappointment that the response rate dropped below 30% ORR in daratumumab-refractory patients. Clearly this therapeutic will see some use in late line therapy, and further clinical development has yielded results in earlier line as reported on 2 March (see https://www.evaluate.com/vantage/articles/news/trial-results/karyopharm-comes-boston-springtime). A similar wait-and-see approach is being taken by these specialists and panelists to the CD3 x BCMA bispecifics, which are currently viewed as best for community hospital settings without CAR T cell capacity or for patients who cannot wait for the cell therapy production.

One theme in r/r MM is the concern that patients are still not being cured, even with cell therapies. The gradual relapse from CAR-BCMA treatment that one sees in all the clinical studies has been linked either to CAR T persistence being limited or to diminished BCMA antigen expression on the cancer cells. Of course, these two things may be related. One desire expressed by Dr Madduri was for a CAR-BCMA therapy with better persistence properties.

Two short notes while we’re here. Gilead stated at their public company presentation during Cowen Health Care that the value driver for the Forty Seven acquisition was the MDS data (https://xconomy.com/san-francisco/2020/03/02/gilead-boosts-cancer-drug-pipeline-with-4-9b-deal-for-forty-seven/). And hematologic drug heavyweight venetoclax (the Bcl-2 inhibitor from Abbvie) scored a miss in an AML confirmatory trial (https//pharmaphorum.com/news/abbvie-roches-venclexta-fails-in-confirmatory-aml-trial/). In summary, a busy couple of days.

As many readers know, Aleta Biotherapeutics builds cellular therapeutics with exemplary persistence and fitness properties. We have two cell therapy programs heading for the clinic now. One will treat r/r AML patients both in the pediatric and adult patient populations. Our solid tumor program is designed to treat patients relapsing from breast or lung cancer with brain metastases. We also have a biologics program specifically created to ‘rescue’ CAR-CD19 T cells in patients relapsing from therapy. You can find out more at www.aletabio.com or email me at paul.rennert@aletabio.com or just call me at 1-508-282-6370 and of course follow me on Twitter @PDRennert and @BioAleta.

That’s it for now.  Stay tuned.

Three high-altitude take aways from AACR14

19-28z CAR, AACR14, ALL, B cell lymphoma, B cell lymphomas, biologics, BITE bi-specific, chimeric antigen receptors, CLL, CTL019, Ibrutinib, immunotherapy, Juno, leukemia, Lymphomas, Leukemias, Myelomas, melanoma, Merck, monoclonal antibodies, Novartis, oncology, Pfizer, rituximab

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The American Association for Cancer Research (AACR) 2014 meeting last week was high energy and high impact. We will dive into particular talks and specific pathways and indications in later posts, in the meantime I wanted to mention a few key themes.

1) Immunotherapy Versus The World.  That’s a deliberate overstatement of a subtle shift in emphasis from last year’s big meetings, where combinations of immunotherapy with just about anything else were the hot topic. This year there were several talks which emphasized the futility of chasing oncogenic pathways and all of their resistance mutations, one after the other, as opposed to letting the immune system do the work. However, it seems to me overly optimistic to believe that immune modulation can defeat a high percentage of patient  tumors on its own, as some speakers acknowledged. Combinations remain necessary although we will have to work past some notable failures in combo trials, such as the liver toxicity seen in the ipilimumab + vemurafenib combination phase 1, discussed briefly by Antonio Ribas               (see http://www.nejm.org/doi/full/10.1056/NEJMc1302338).

2) Immunotherapy Versus Itself.  In the ultimate battle of the titans, we see different immunotherapeutic modalities squaring off. This is a theme we’ve touched on before in this space, but the  competition is getting heated. In some indications, the leukemias, lymphomas, perhaps melanoma and some other solid tumors, there is an abundance of therapeutic choices, and the hard question of which therapy best suits which patient will ultimately need to be addressed outside of the context of clinical trial enrollment. Several talks really brought this message home. Roger Perlmutter of Merck (and before that, Amgen) envisions an important role for multiple immune therapies including bi-specific antibodies, chimeric antigen receptors (CARs), and immune checkpoint modulators like Merck’s anti-PD-1 antibody MK-3475.  For B cell lymphoma for example, there is blintumumab (Amgen), a potent bi-specific that redirects T cells to CD19+ tumor cells (and normal B cells), and there is CTL019, a CAR therapeutic which does much the same thing. The therapeutic profiles and toxicity differ, but the general idea is the same. One big difference is that while CTL019 drives T cell expansion and the development of long term anti-tumor memory, the bi-specific does not. Which is better? We don’t know yet. He did not mention that one might do well trying a course of BTK inhibition plus anti-CD20 antibody therapy, perhaps with restricted chemotherapy first e.g ibrutinib plus rituximab and chemo (R-BR or R-F). That choice comes down to efficacy, then toxicity, and eventually cost. Efficacy seems to be a home run with the CAR therapeutics, although these may run into trouble in the area of toxicity and cost calculation. Renier Brentjens discussed the CAR therapies being developed under the Juno Therapeutics umbrella. Acute lymphoid leukemia (ALL) can be treated with CAR 19-28z modified T cells to achieve a >80% complete response rate with >70% of patients showing no minimal residual disease, an outstanding result. However, 30% of treated patients end up in the ICU due to cytokine release syndrome and other toxicity, and recently patients in the ALL trials have died from unanticipated tox causes. Juno stopped 5 trials of their CAR technology last week due to toxicity. Apparently one patient died of cardiovascular complications and another of CNS complications (severe uncontrolled seizures) – it was hard to nail down as Dr Brentjens had gone off his prepared talk for these remarks which were off the cuff, so comment please if you have better info on this. Carl June discussed Dr Brentjens’ presentation, noting that the clinical results were really quite striking, and contrasting the CD28 motif-based CARs with the 4-1BB-based CARs (as designed by Dr June with U Penn and licensed to Novartis). He also stressed that in chronic lymphocytic leukemia (CLL) they have had patients who have failed up to 10 prior therapies, including rituximab and/or ibrutinib, and these patients have responded to CAR treatment. That’s very impressive data. The roadblocks to widespread use of CAR therapy however are large and include the toxicity, the “boutique” nature of the current protocols, the cost. Perhaps, Dr June suggested, CAR will end up as third line therapy, reserved for salvage therapy. I for one hope not.

Also in the immunotherapy space were hot new targets (e.g. CD47, OX40, GITR), advances on the vaccine front, and a few surprises. We’ll update soon.

3) The Medicinal Chemists Have Been Busy.  Not to be drowned out by the Immunotherapy tidal wave, small molecule therapies targeting specific oncogenic pathways continue to be developed and show promise. Most readers will be aware of the high stakes showdown (so billed) between Novartis, Pfizer and Lilly in the field of specific CDK4/6 inhibitors – in addition to bringing forward some really nice phase 2 data (we’ll discuss these another time) this “showdown” also illustrates that current portfolio strategy drives a lot of overlapping effort by different companies. As expected, much of the action is moving downstream in the signaling pathways, so we saw some data on MEK1 inhibitors and ERK1/2 inhibition. There were some new BTK inhibitors, nice advances in the epigenetics space, and some novel PI3K inhibitors. All grist for the mill.

stay tuned.

Kites Fly: Effective CAR-T Therapy in Non-Hodgkin Lymphoma? Hematological Malignancies Part 4

ALL, AML, B cell lymphoma, B cell lymphomas, CAR-T, chimeric antigen receptors, immunotherapy, Kite Pharma, lymphoblastic leukemia, Lymphomas, Leukemias, Myelomas, monoclonal antibodies

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Sorry for the slight delay getting this out. I was trying to account for each patient as even 1 or 2 misplaced will impact the response numbers in these small trials. Took a while.

Our last post focused on the CAR technology coming out of the MSKCC and affiliated institutions, being brought together under the Juno company umbrella. Juno was funded by ARCH Venture Partners and the Alaska Permanent Fund, through a partnership managed by Crestline Investors, along with Bezos Expeditions, and Venrock. We noted in closing that CAR T cell technologies were performing very well in acute lymphocytic leukemia (ALL), but not as well in the Non-Hodgkin Lymphomas (NHL). In early data sets response rates were not trending very high.

Recently I came across Kite Pharma’s JPM update on their version of CAR therapy. Kite is financed by Pontifax Ltd., Alta Partners, Commercial Street Capital, and individual investors, in partnership with the National Cancer Institute (NCI) Surgery Branch under a Cooperative Research and Development Agreement (CRADA). This reflects that the technology is coming out of NCI labs.

I was struck again by the duration and response rates reported and the indications they were pursuing. It seems that there is one extra patient in the JPM slide deck, so I went back to the ASH talk to get the right numbers. So lets review. Kite calls its lead CAR construct a very straightforward name: anti-CD19 CAR. Like 19-28z CAR from Juno/MSKCC, this CAR is built with a anti-CD19 scFv, followed by CD28 and CD3 signaling components. Quite unlike the 19-28z effort however, the lead here is NHL indications, specifically as seen here:

Screen Shot 2014-03-26 at 5.28.38 PM

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Hematological Malignancies – who will win the battle for patients? Part 2: BiTEs & CARTs targeting CD19

ALL, Amgen, B cell lymphoma, B cell lymphomas, biologics, BITE bi-specific, CAR-T, chimeric antigen receptors, CLL, DART bi-specific, genetic engineering, immunotherapy, lymphoblastic leukemia, monoclonal antibodies, Novartis, oncology, rituximab

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 We talked last time about the potential of Macrogenic’s DART bi-specific technology and we focused primarily on the T cell engaging bi-specifics, such as DART006, a CD3 x CD123 therapeutic. Lets just quickly state the hypothesis:

Bi-specific modalities will allow the targeting of the patients T-cell driven immune       system to a precise (tumor-expressed) antigen.

Other outcomes are possible. For example, the drugs might not work at all, or they might not be as specific as designed, or they act in ways we have not anticipated. In the context of the Macrogenics platform, we actually don’t know yet, as DART006 is very early in clinical development. BiTEs (Bi-specific T cell Engagers), Micromet’s version of a bi-specific technology, have been around a while and are further advanced. Acute Lymphocytic Leukemia (ALL) patients are now being recruited into Phase 3 clinical trials for blinatumomab, the anti-CD3 x anti-CD19 BiTE, with study completion due in July 2017. Micromet was acquired for 1.2BB dollars in January 2012 by Amgen. At the time Amgen R&D head Roger Perlmutter pointed to the Phase 2 clinical trial results in ALL as driving Amgen’s interest in the technology. Indeed, blinatumomab has produced some remarkable data in ALL. Historically, chemotherapy treated ALL patients had a complete response rate (CR) of about 38% and a median overall survival (OS) of 5 months. Rituximab (anti-CD20) didn’t perform much better than chemo. In the blinatumomab Phase 2 trial of adult relapsed/refractory (r/r) ALL, patients received a continuous IV infusion of blinatumomab for 28 days followed by 14-days off drug. Patients who responded could re-up for 3 more cycles of treatment or proceed to allogeneic stem cell transplantation (HCST). There was a very high rate CR of ~70% and the apparent absence of minimal residual disease (MRD) in many patients. Blinatumomab also impacted overall survival (OS) in ALL, as reported at the American Society of Hematology conference (ASH) in 2012 (Abstract #670). The CR was still 69% with most patients being MRD negative. The OS for responders was 14.1 months while the OS for non-responders was 6.6 months (so median OS = 9.8 months). Thirteen of the 36 patients enrolled were able to receive allogeneic HSCT.

The most common adverse events (AEs) were fever, headaches, tremors, and fatigue. Some patients experienced severe AEs (SAEs) such as cytokine release syndrome (CRS) and central nervous system events, including seizures and encephalopathy. One patient stopped treatment due to fungal infection leading to death. So, there is tox to consider.

A smaller study directed to salvaging patients with MRD despite prior treatments showed even more dramatic results: 16/21 patients became MRD negative and the probability for relapse-free survival was 78% at a median follow-up of 405 days. This is a remarkable result. An SAE led to one drug discontinuation.

Last year at ASH (Abstract #1811) we saw early results from an open label phase 2 study in r/r Non-Hodgkin’s Lymphoma (NHL), specifically, Diffuse Large B cell Lymphoma (DLBCL). Blinatumomab was administered by continuous IV for 8 weeks. Patients received either stepwise blinatumomab dosing of 9, 28, and 112 μg/d during weeks 1, 2, and thereafter, or received 112 μg/d throughout. All patients received prophylactic dexamethasone. So you can see some dose modifications here designed to reduce SAEs. After a 4-weeks off drug, patients who had responded could receive a 4-week consolidation cycle. 11 patients had been enrolled, 7 patients were evaluable for response. These patients had failed >2 prior therapies, including some patients who had relapsed after HSCT. The overall response rate (ORR) was 57% (14% CR plus 43% partial response (PR); 30% had progressive disease (all from the stepwise dose regimen). Note this is a very small sample size so every patient has a large impact on the response numbers. Ten of 11 patients had at least one grade ≥3 AE with 2 patients having grade 4 AEs (one patient with neutropenia and leucopenia; one with respiratory insufficiency). There were no drug related fatalities. Ten of 11 patients had central nervous system (CNS) AEs, mostly tremor, speech disorder and disorientation: in 5 patients these CNS toxicities were grade 3. The overall benefit/risk assessment suggested stepwise dosing (9, 28, 112 μg/d) to be the recommended dose.

Well first of all let’s point out here that blinatumomab has orphan drug status for ALL and NHL. That’s just to remind ourselves that these are pretty rare diseases with high unmet need. For ALL in particular this seems a good risk/benefit scenario. Within the diseases that make up NHL, DLBCL is not the most treatable (nor the least), and we note also that there is no attempt in the open-label phase 2 to characterize DLBCL into its subclasses – these have different oncogenic drivers and different outcomes for patients. Blinatumomab has also been in Phase in in other NHL classes, including Mantle Cell Lymphoma and Follicular lymphoma. Response rates were generally below current standard of care. Similarly, we can go back to look at rituximab, ofatumumab, and even ibrutinib, idelalisib and ABT-199 in NHL and likely find better treatment paradigms for r/rDLBCL than this, although maybe not as a monotherapy (see those earlier posts here: http://www.sugarconebiotech.com/?p=16).

Given the modality (CD3 x CD19 bi-specific) maybe the most interesting comparison is with Novartis’ CAR-T CD19 technology CTL019. CTL019 is the product of genetic engineering technology developed by Carl June’s group at U Penn, and is currently advancing in close to 20 clinical trials. The most advanced is a Phase 2 trial in r/r ALL, with a primary outcome completion due in July of 2015. As a quick reminder, CARs combine a single chain variable fragment (scFv) of an antibody (e.g. anti-CD19) with intracellular signaling domains from CD3 and 4-1BB into a single genetically engineered chimeric protein. The CD19-specific version of this technology is termed CTL019. Patient’s T cells are lentivirally transduced with a CAR, expanded ex vivo then infused back into the patient. Infusion of these cells results in 100 to 100,000x in vivo T cell proliferation, anti-tumor activity, and prolonged persistence in patients carrying CD19+ B cell tumors. Results from a pilot study in pediatric and adult r/r ALL were presented at ASH in 2013 (Abstract #67). Most patients received lymphocyte-depleting chemotherapy just a few days prior to infusion. This helps de-bulk the malignancy. In this small trial, 82% achieved a CR, 18% did not respond. Of the patients achieving CR, 20% subsequently relapsed. The rest of the patients are being followed and there has been no update. Responding patients all developed CRS, and about 30% of patients were treated with the IL6-receptor antagonist tocilizumab plus corticosteroids to control CRS symptoms.

We have a little more data on CTL019 from NHL studies, specifically r/r CLL. In December 2013, Phase 2 data were presented at ASH (Abstract #873).  Patients with r/r CLL received lymphocyte depleting chemotherapy and then one of several doses of transduced T cells (this is a dose study in that regard, although, cutting to the chase, no dose response was seen, so lets skip over that). Median follow-up for analysis was 3 months at which time the ORR = 40% (20% CR plus 20% PR, with clearance of CLL from the blood and bone marrow and at least a 50% reduction in lymphadenopathy. The toxicity profile was similar to that described above, dominated by treatable CRS. In a small Phase 1 study (Abstract #168), adult patients with r/r NHL including patients with chemotherapy-refractory primary mediastinal B cell lymphoma and DLBCL were enrolled. They received chemo to reduce disease burden and then an infusion of CTL019. 12 of 13 evaluable patients responded (ORR = 93%), the CR = 54% and PR = 38%. These are outstanding responses.

So let’s take a step back. It is a bit hard to compare these regimens head-to-head as they are in different stages of clinical development, the trails are generally small, and in the case of NHL, we have limited data on different types of lymphomas. At the same time we have to consider the larger landscape of therapies available, and ask ourselves how patients will best be served. In the case of the T cell engaging bispecific antibody landscape, it is very clear that robust anti-tumor responses are generated with very low concentrations of antibody. It seems to me very likely that there will be malignancies or subsets of malignancies where this technology will be very useful, including ALL, as we just saw. It will be important to either improve the antibody construction or alter the dose regimen sufficiently to reduce the toxicities associated with the BiTE therapeutic and competing modalities, including the DARTs. Now, people will claim that the tox is not so bad, and that it is only efficacy that matters, and that’s fine, but in the face of competition from CTL019 and other therapeutics, maybe this becomes a differentiating issue. This might also be different for the pediatric population (a critically important population in ALL) versus the adult population. When we look at the CAR T cell transduction technologies we need longer follow-up on the phase 2 studies but certainly anecdotal evidence from smaller trials suggests that some patients will experience long-lasting remissions. If this observational information holds up in the larger clinical trials than the technology will cement itself a place in ALL therapy, and perhaps in other diseases as well. We don’t know yet whether the BiTE therapeutic blinatumomab or the CAR therapeutic CTL019 will have a top-tier profile in NHL. This may change as more data become available, as some of the small studies are very encouraging. One of the interesting twists to the CAR technology is the question of how to make it widely available. In host-institutions (The U Penn system, MD Anderson, NCI) this is a centralized procedure, and in medical institutions world-wide, core patient cell facilities are commonplace. However it is rumored that Novartis at least wants to maintain the core facility model, as they picked up the Dendreon facility in Morris Plains New Jersey (at a bargain price) specifically to support CAR technology, and plan to duplicate those capabilities in Basel and in Singapore. Perhaps yesterday’s pickup of Israel’s Gamida Cell also plays into this centralized cell handling model. None of these complexities will bother the bi-specific therapeutics as these are injectable – that said, I’m not sure anyone will choose walking around with an IV pump for two months if they can avoid it.

So while these therapies and those like them are very potent, we will have to see how patients and providers ultimately use them.

Now, we’ve unfairly used blinatumomab and CTL019 to illustrate what are both pretty large areas of therapeutic development. We’ll come back to talk about the other players in the bispecific antibody and CAR spaces very soon.

stay tuned.

SnapShots from the 2013 American Society of Hematology Abstracts – Part 5

#ASH13, ASH13, B cell lymphomas, biologics, monoclonal antibodies, obinutuzumab, ofatumumab, rituximab

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Part 5. Key Biologics in Clinical Trials.
November 20, 2013
The American Society of Hematology Meeting will take place in New Orleans,
December 7 – 10, 2013. The abstracts are available at http://www.hematology.org/Meetings/Annual-Meeting/Abstracts/5810.aspx
In parts 1-4 we meandered through the small molecule, mainly oral drugs,
highlighting a few key pathways and focusing mainly on CLL.
Biologic drugs are a different and equally important class of therapeutics for lymphoma
treatment, and really it is Rituxan, the antibody that depletes cells expressing CD20, that
ushered in the new era of non-chemotherapy-based drugs. Some of the small molecule
trials discussed earlier were done in combination with anti-CD20 antibodies with or
without added chemotherapy. This therapeutic trend toward combination therapy will
dominate the lymphoma landscape, with chemo, targeted small molecules, and antibodies available to mix and match, just so long as they are not too toxic when combined, provide additive efficacy, and we can afford to pay for them. One might also overlay immuno-
therapy approaches – checkpoint modifiers, CAR-T modified cells, even cancer vaccines –
and of course there is also the whole bone marrow or stem cell transplantation field.
There are notable new biologics being developed for the treatment of lymphoma, and a
few of these have new data available in the ASH 2013 abstracts.
The real question is whether anything will be able to compete with the novel anti-CD20
mAb obinutuzumab.
Obinutuzumab (GA101) is aglycoengineered antibody having 10-fold greater affinity 
for FcgammaR3A. This is receptor on cytotoxic NK cells that binds to the Fc domain 
of the antibody. The binding of the Fc domain to the FcR (receptor) triggers killing of 
the target (CD20+) cell by the interacting NK cell. Obinutuzumab was approved under 
the brand name Gazyva on November 1st for use in combination with chlorambucil to 
treat patients with previously untreated CLL. This was this first drug approved under 
the FDA’s new breakthrough therapy designation and wasbased on a Phase 3 study of 
previously untreated CLL patients (n = 365) comparing Obinutuzumab plus chlorambucil 
to chlorambucil alone. The PFS for the combination therapy was 23 months compared 
with 11.1 months with chlorambucil treatment. Additional data from the Phase 3 trials, 
comparing obinutuzumab pluschlorambucil (OB-c) to rituximab (Rituxan) plus 
chlorambucil (R-c), are to be presented during the plenary session at ASH (Abstract #6). 
Those data are summarized as follows:
ORR
CR
MRD*
PFS
OB-c
78%
21%
29.4%
26.7 months
R-c
65%
7%
2.5%
15.2 months
*: MRD is minimal residual disease, meaning that bone marrow and organs are negative 
for tumor cells.
AEs were higher in the obinutuzumab plus chlorambucil arm, although it appears that 
this was due to increased severe infusion-related reactions, which can be controlled.
Another study in previously untreated CLL patients will be presented at ASH (Abstract
#523). In this trial, obinutuzumab (OB) was combined with fludarabine/cyclophosphamide 
(FC) or bendamustine (B). There are 41 patients enrolled and the median reported followup 
time is nearly 12 months. 9 patients (22%) had to discontinue treatment due to AEs, mainly cytopenias. The investigators will report and update response data, summarized here (note 
that CRi, defined as complete response with incomplete bone marrow resolution, is included 
in this table with the %PR):
ORR
CR
PR
SD
PFS
OB-FC
62%
9.5%
47.6%
19%
not reached
OB-B
90%
20%
70%
0
not reached
No responding patients progressed and PFS was not reached. While the data look very good
for efficacy, the fact that a high percentage of patients had to discontinue due to AEs is
notable.
Two other studies will be presented at ASH. One is on the treatment of CD20+ Diffuse
Large B Cell Lymphoma (DLBCL) patients in a Phase 2 clinical trial (Abstract #1820).
DLBCL is an aggressive lymphoma, currently treated with combination chemotherapy
(CHOP: cyclophosphamide, doxorubicin, vincristine, prednisone) or with rituximab plus combination chemotherapy (R-CHOP). In this trial, 80 previously untreated DLBCL
patients were treated with obinutuzumab plus CHOP. The ORR = 83%, consisting of
CR = 55% and PR = 28%. Of the 80 patients total, 11 patients discontinued treatment,
5 of these due to AEs (6.25%), but in general AEs were manageable. Nine patients had
PD, three died. These preliminary results are very encouraging, updated results including
analyses responses in DLBCL subsets (ABC v GC) and with reference to molecular
classification will be presented at the meeting. An earlier study (Abstract #1814) will
present data on the use of obinutuzumab as maintenance therapy after induction therapy
with chemo (either OB-CHOP or OB-FC). Patients had rrFL (follicular lymphoma). The
induction data was published by Radford et al. in Blood, 2013, volume 122, page 1137ff. 
CR rate was monitored at the start and end of maintenance therapy, with the maintenance 
period being a median of 35 months across the two cohorts. CR as a best overall response increased on maintenance with obinutuzumab in the OB-CHOP cohort (52%, PFS not 
reached) and in the OB-FC cohort (82%, median PFS = 46 months). Finally, a combination 
trial of obinutuzumab and ABT-199 is currently in phase Ib (NCT01685892).
These studies show benefit of obinutuzumab therapy in different lymphoma populations
using a variety of treatment paradigms, and point to the importance of this biologic
therapy in B cell lymphoma treatment.
There are a large number of new biologics competing for attention; just a few are discussed
here.
Another anti-CD20 antibody with breakthrough status is ofatumumab (Arezza). Approved in
2009 for use in rrCLL patients, this antibody is moving toward use earlier (i.e. in newly
diagnosed CLL) and in other patient subsets.
In May of this year, positive phase 3 data for ofatumumab were announced by GSK. Patients
with previously untreated CLL (n = 447) received ofatumumab plus chlorambucil (OF-C) or chlorambucil (C) alone. The study found that patients in the ofatumumab cohort experienced
a longer median PFS. That study will be updated at ASH (Abstract #528). Top line data is
here:
PFS
ORR
CR
MRD
OF-C
22 months
82%
12%
4%
C
13 months
69%
1%
0
Other studies on ofatumumab being presented at ASH include a phase 2 trial in combination
with dexamethasone, to treat high risk rrCLL patients (Abstract #2877). This study presents
a CR = 16% and PFS = 10 months, although the infection risk was quite high. Another
phase 2 study is testing the efficacy of ofatumumab in combination with the AKT inhibitor afuresertib (Abstract # 4175) in the treatment of high-risk rrCLL patients. In this small
study (n = 19) AEs were manageable (neutropenia, GI complications) but responses were
low: ORR = 42%, CR = 0, PR = 42%; 58% of patients had SD, and 26% of patients
progressed. Several other trials will also be updated (Abstracts #1645 and 4177).
An example of the high bar set by obinutuzumab therapy can be seen in several trials of
other biologics. Pfizer has developed an antibody/drug conjugate (ADC) called inotuzumab ozogamicin (InO). This is a humanized anti-CD22 antibody conjugated with calicheamicin, 
a potent cytotoxic. CD22 is expressed on most forms of NHL. The trial (Abstract #1821) 
is a phase 1 dose escalation trial designed to identify the MTD in combination with 
rituximab plus chemo (gemcitabine, dexamethasone, and cisplatin). AEs, mostly
cytopenias, causing dose reductions and dose delays established the MTD. Patients had 
rrNHL, with 21 DLBCL, 14 FL, 12 MCL, 4 SLL, 1 MZL, and 3 other indolent B-NHL.
At the MTD dose the ORR = 45% and the CR = 22%. Of the 55 patients enrolled, 12
(22%) discontinued due to AEs and 12 (22%) discontinued due to PD. These numbers
are a little worrisome although this is a difficult patient population to treat. It will be
important to see PFS and OS numbers as clinical development of this therapy continues.
An intriguing target for antibody development is CD37. CD37 is tetraspan protein expressed
on a variety of hematopoietic cells, and can transmit a cell death signal through its SHP-1
domain. Trubion engineered a modified antibody called TRU-016, now being developed by Emergent (see the 14 November issue of Blood – volume 122, p 3397 – for a brief description 
of this and other anti-CD37 targeting agents). Phase 2 data on TRU-016, now called 
otlertuzumab, will be presented at ASH. Otlertuzumab induces cell death directly (ie. by 
signaling cell death) and also through Fc-mediated cytotoxicity. The phase 2 trial recruited 
65 rrCLL patients who had failed between 1 and 3 prior therapies. The Abstract (#2860) 
presents data on 44 evaluable patients treated with otlertuzumab (OTL) or with otlertuzumab
plus bendamustine (OTL-b). The data are as follows:
treatment
ORR
CR
% progression
OTL
42%
4%
46
OTL-b
80%
20%
10
The % progression data refers to the responding patients only. AEs were in line with the chemotherapy treatment. A second study (Abstract #4165) provides preliminary data on
patients treated with otlertuzumab plus the anti-CD20 antibody rituximab (Rituxan). This
dual antibody therapy was given to previously untreated CLL patients. Preliminary data
suggest an ORR = 88%, and modest AEs. This trial will be updated at the meeting. These
early studies suggest that targeting CD37 is an attractive approach for CLL therapy.
BITE antibodies are bi-specific antibodies originally developed by Micromet. They have
received a lot of press following the 1.2 billion dollar acquisition of Micromet by Amgen. Blinatumomab binds to CD3 on T cells and CD19 on lymphoma cells, helping to direct the
T cells to recognize and destroy the tumor cell (BITE stands for BI-specific T cell Engager). Abstract #1811 has some very early data on blinatumomab treatment of rrDLBCL patients.
Lets be clear upfront that this is a tough patient group to treat. At the time of abstract
submission, 11 patients were enrolled with initial ORR = 57%. It will be very interesting
to hear updated results from this trial at ASH, including both efficacy and AEs, which at
first glance seem tolerable if unpleasant (including CNS toxicity).
MEDI-551 is an afucosyl-anti-CD19 antibody with augmented cytotoxic activity (due to the
lack of fucosylation of the antibody). An 83 patient Phase 1 trial (Abstract #1810) enrolled heavily pretreated rr CLL, DLBCL, FL, or MM (multiple myeloma). All of these B cell lymphoma types are CD19 positive. The ORR = 25%, with CR = 10.8% and PR = 14.5%.
50.1% of patients were characterized as SD. PFS was calculated to be 9 months. At first
glance the single agent responses are substandard; MedImmune is continuing development
of MEDI-551 in combination with chemotherapy.
A CD19 ADC has advanced to phase 2, in a combination trial with rituximab (Rituxan).
SAR3419 is a humanized anti-CD19 antibody conjugated to maytansin DM4, a cytotoxic
agent. It is under development by Sanofi and was licensed from ImmunoGen. This ADC
was given along with rituximab (Rituxan) to rrDLBLC patients (refractory to first line
therapy or relapsed after a prior therapy; Abstract #4395). ORR was low at 31% and 36%
of responders progressed by the end of the study. Sanofi plans to move this agent into
patient populations that may be more responsive.
So, here we have seen two anti-CD19 antibody therapeutics with rather poor efficacy
profiles.
I want to end with an old dog/new trick story concerning alemtuzumab. First studied many
years ago in the context of transplant rejection therapy, this anti-CD52 antibody lives on as
a treatment for hematological malignancies (CD52 is widely expressed) and, under the
brand name Lemtrada, as a therapy for multiple sclerosis. The long strange trip of this
nasty antibody (the side effect profile is not good) is the subject for another day. Of interest
at ASH however is a nice study looking at the utility of alemtuzumab for very high risk
treatment naive CLL patients (Abstract #2861). High risk is defined here genetically – these
are patients with genetic deletions or mutations known to be associated with poor prognosis. Without diving into the details, the investigators have shown that TP53 mutations had an
adverse prognostic impact and shorter PFS and this was overcome by alemtuzumab treatment. This then presents itself as a potential therapeutic for patients known to have this poor risk
factor.
If time allows I want to discuss the CAR-T technology, perhaps in the next section.

SnapShots from the 2013 American Society of Hematology Abstracts – PART 2

#ASH13, $PCYC, ASH13, B cell lymphomas, Ibrutinib

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Part 2. Small molecule BTK inhibitor Ibrutinib in the treatment of Chronic Lymphocytic Leukemia (CLL).
November 15, 2013
The American Society of Hematology Meeting will take place in New Orleans, December 7 – 10, 2013. The abstracts are available at http://www.hematology.org/Meetings/Annual-Meeting/Abstracts/5810.aspx
Note that I’ve defined most of the terms we are using in Part 1, so please refer to that section for help with any abbreviations. In Part 1 is also some background on CLL and the signaling pathways downstream of the B Cell Receptor, which are targeted by these drugs. Finally, I introduced the patient populations typically encountered in CLL clinical trials.
So now we come to the Btk inhibitors and specifically to Ibrutinib, the Pharmacylics compound partnered with the Janssen arm of Johnson & Johnson. This soon-to-be blockbuster drug has been approved for the treatment of Mantle Cell Lymphoma (MCL) at an anticipated cost of 150,000 USD/year.
As mentioned in Part 1, CLL is the most common of the B cell lymphomas, so it is of keen interest to see how Ibrutinib performs in that patient population, especially given the efficacy seen with Idelalisib from Gilead.
Abstract #675 presents data from a 40 patient phase 2 trial in which Ibrutinib (IBRU, 420mg/day) was given with Rituxan anti-CD20 antibody (Rtx). The trial is notable for the inclusion criteria that enrolled patients only if they had high-risk disease: del(17p) or TP53 mutation (treated or untreated), PFS < 36 months after frontline chemotherapy + anti-CD20 treatment, or relapsed CLL with del(11q). Most patients responded well (see the table), very few patients were lost to followup and AEs were well tolerated.
Abstract #525 presents data from a small phase 1b trial in high-risk rrCLL/SLL patients (SLL is a form of CLL called small lymphocytic lymphoma, in which most of the cancer cells are located in lymph nodes). In this trial patients received IBRU + Rtx + B (bendamustine, see part 1). The response rate was very high (see the table) although the authors do note that 30% of patients eventually discontinued treatment, 10% due to progressive disease. Responses appeared to be independent of specific high-risk cytogenetic factors. Grade 3 or higher AEs were GI related, cytopenias (including 6.7% febrile neutropenia), and infections. The data from these 2 abstracts are shown below, and compared to published data (Byrd et al. 2013 NEJM 369:32-42). Note the caveats described above when reading these response percentages.
 
 
It is a little hard to directly compare these results with the Idelalisib data, partially reproduced here from Part 1, with one correction to the table (column 3: DOT = median duration of treatment):
 
 
It is tempting to conclude that the response rates with Ibrutinib are a little higher, but such comparisons will required much larger data sets. At the moment it is fair to say that these therapeutics both provide superb novel options for rrCLL patients.
Returning to Ibrutinib, there will be additional data from monotherapy studies shown at ASH. Abstract #4163 reports on an extension study of Ibrutinib monotherapy in treatment-naive CLL and in rrCLL patients. An important parameter of this study is that it included treatment-naive (likely newly diagnosed) patients; the data for discontinuation due to disease progression (PD) shows that nearly all of these early-treated patients maintain a response for at least the DOT.
After 2.5 years, 76% of this patient population was still alive, an impressive number.
Abstract #673 also examined the impact of Ibrutinib monotherapy, in this case in elderly patients with or without the del(17p) cytogenetic factor indicating high risk for progression. In this study there was a significant difference in the PR percentage, with 81% of patients with wild-type 17p responding while only 53% of patients with a deletion of 17p responded (p = 0.04). This suggests more (or larger) studies will be required to sort out the best patients for Ibrutinib therapy.
A very nice study will be presented by investigators at The Ohio State University (Abstract # 2872). Using multivariate analyses of patient response, progression and survival, these investigators compare Ibrutinib monotherapy to checkpoint-inhibitor therapy (alvocidib, dinaciclib, or TG02) to “other” therapy, in del(17p) rrCLL patients. “Other” is unfortunately not identified, but must include standard-of-care, which would normally be chemotherapy plus Rituxan. Here is a snapshot of the data at 24 months (the analysis is beautiful and I won’t reproduce their graphs here):
These data really drive home the importance of the new therapeutics and new therapeutic combinations, where we are seeing improvement in PFS.
There are a swarm of newer small molecule drugs coming up, and these will be covered in Part 3.

SnapShots from the American Society of Hematology Abstracts, Part 1

#ASH13, $GILD, ASH13, B cell lymphomas, idelalisib, Idelalisib phase 3

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November 15, 2013
The American Society of Hematology Meeting will take place in New Orleans, December 7 – 10, 2013. The abstracts are available at http://www.hematology.org/Meetings/Annual-Meeting/Abstracts/5810.aspx
Part 1. Small molecule PI3Kdelta inhibitor Idelalisib in the treatment of Chronic Lymphocytic Leukemia (CLL).
It is useful to remember that most CLL patients have indolent disease and are in a “watch and wait” mode with their physicians, who will not initiate treatment unless they see signs that the cancer is becoming active and/or the patient has one or more risk factors. Therefore in clinical trials the CLL patients are those at high risk. Typically “relapsed or refractory” CLL (rrCLL) patients have cytogenetic markers of poor prognosis (mutated p53, del(17p), del(11q), trisomy 12, mutated NOTCH1), or are patients who have failed multiple prior therapies (chemotherapy and/or antibody therapy such as Rituximab treatment), patients with “bulky” disease indicating lymph node and other lymphoid organ involvement, and patients with unmutated IGVH sequences. Often these high risk markers occur together. It is important to realize that at this time CLL is not considered a curable disease, and that the goal is therefore to increase median progression-free survival (PFS) and median overall survival (OS), the latter referring to time until death.
That said, we are witnessing a remarkable time. Terrific new therapies are being developed, and physicians look forward to offering their patients a chance at a cure.
Lets start with a drug class I think has great promise, inhibitors that act downstream of B cell receptor (BCR) signaling. CLL is a B cell lymphoma, and is dependent on chronic activation of these signaling pathways. Here is a model to get us oriented, from the Onclive website:
Note that Syk, Btk and PI3K are upstream (relative to the cell surface and BCR) and therefore are critical components of the pathway. Drugs targeting each of these signaling kinases have been developed. AKT, mTOR and others, generally more familiar to us from the solid tumor literature, are further downstream.
There are four isoforms of PI3K relevant to the drug class: alpha, beta, delta and gamma. Different drugs have selectivity for one or more of the isoforms.
For treatment of CLL, the lead therapeutic in the class Idelalisib is a PI3Kdelta(d) selective inhibitor from Gilead. PI3Kd signaling is known to be essential for the activation, proliferation, survival and tissue homing activity of lymphoma cells. On October 9th a phase 3 CLL clinical trial of this drug was stopped ahead of schedule based on a positive risk/benefit assessment. The drug is also under New Drug Application (NDA) review for indolent Non-Hodgkin’s Lymphoma iNHL) based on results from multiple phase 3 trials. Idelalisib is trailing just a step behind Ibrutinib, a BTK inhibitor, in the approval process – Ibrutinib was approved for Mantle Cell Lymphoma (MCL) on November 12th. Neither drug is approved for CLL, the most common lymphoma.
Both drugs have moved aggressively into combination therapy trials. Some of the early trials (phase 1 and 2) will report out interim data at ASH.
Abstract #4176 presents analyses of Idelalisib (IDELA) given in combination with Rituximab (Rtx) antibody therapy plus chemotherapy (B: bendamustine or C: chlorambucil) in high-risk rrCLL patients. Results are encouraging and shown in Table 1, where ORR = stable disease (SD) + partial response (PR) + complete response (CR). Its important to note that these are clinical trial terms and do not reflect outcomes, just observations at specific timepoints. Regardless we are looking for high % ORR, PR and CR. Importantly, the median duration of exposure was 18 months at the time of analysis, meaning that 18 months is the median amount of time patients have been exposed to drug without withdrawing due to toxicity, disease progression, or death. More importantly, the median duration of response (DOR) to therapy had not been reached within the 18 months (so that’s good, patients are still on drug and are still responding) nor had the median PFS been reached (so more patients have survived than have not survived). The IDELA-Rtx-C data are similar, just of shorter average duration with a median exposure = 7.7 months (I’m guessing here that this arm of the trial enrolled later). Also notable is the toxicity data from this trial, which tracked pretty consistently with the chemotherapy regimen. When the combination therapy included bendamustine, neutropenia was the defining toxicity, with > 60% of patients experiencing grade 3-4 neutropenia. When the combination therapy included chlorambucil, liver transaminase elevation was the defining toxicity, with > 21% of patients experiencing grade 3-4 liver toxicity. Its important to realize that these are severe, but manageable, toxicities for most patients.
Abstract 2878 presents a similar study, but in this case the combination therapy given with Idelalisib was limited to chemotherapy. Chemotherapy consisted of B: bendamustine, F: fludarabine or C: chlorambucil, given in standard doses. This trial was run in a heavily pre-treated patient population having a very poor prognosis. The data are very encouraging given the composition of the enrolled patient population (Table 1). The adverse events (AEs) were cytopenias and gastrointestinal tract (GI) disorders. This study demonstrates that Idelalisib has potent activity in combination with chemotherapy.
Abstract 4180 gives us data from an additional study, in which Idelalisib is paired with anti-CD20 antibody therapy (Table 1). As in the other studies the cohorts were comprised of a high risk patient population. This was a small phase 1 study with an extension arm, enrolling 40 patients. This study produced some sobering results that remind us how serious a disease aggressive CLL is, and how potent the drugs treating this disease have to be. Notably, 25% of patients did not enter the extension study due to disease progression, 6 patients died. A further 23% did not enter the extension study due to AEs. These data remind us that response rates readout at a specific pre-determined time during the trial, and do not reflect outcomes. Regardless the median PFS and DOR for all patients (N=40) and were 20 and 19 months, respectively. Median overall survival (OS) had not been reached.
The phase 3 study mentioned at the outset, which was stopped early due to significant evidence of clinical benefit, was very similar to, if much larger then, the Phase 1 study presented in abstract 4180. We don’t know much about the trial data yet, but Gilead’s press release states that the “Phase 3 study … evaluating idelalisib in previously-treated … CLL patients who are not fit for chemotherapy will be stopped early  … based on a predefined interim analysis showing highly statistically significant efficacy for the primary endpoint of progression-free survival in patients receiving idelalisib plus rituximab compared to those receiving rituximab alone. The safety profile of idelalisib was acceptable and consistent with prior experience in combination with rituximab in previously treated CLL.”
I think the general takeaway here is that a high proportion of those patients who respond did well over time. The fact that they did so without additional chemotherapy is very encouraging. PFS in either not being reached or is reached at 20 months or so. This suggests that impact on OS will be significant for all of the drug combinations presented. 
 
Additional analyses from Phase 1b and 2 studies were presented in abstract #1632. This abstract presents data comparing responses among CLL patients with high risk prognostic markers (del(17p) or TP53 mutation, del(11q), IGHV mutation and NOTCH1 mutation) to CLL patients without these markers. rrCLL patients given Idelalisib monotherapy or combination therapies responded equally well to treatment regardless of the presence or absence of these critical genetic markers of disease aggressiveness. That is a very important result that suggests great potential for CLL therapy with Idelalisib. The table is below.
 
Note that the response rates in the phase 2 Idelalisib + Rtx trial in previously untreated (i.e. newly diagnosed) patients are quite high, and this is exactly what you want to see as to drug moves to treat patients earlier in their disease course.
Next up is a review the Ibrutinib data in the same disease, and also a quick look at the other therapies in these drug classes.

Apoptosis Induction for the Treatment of B Cell Lymphomas: Update on AbbVie’s Bcl-2 Inhibitor ABT-199.

$ABV, AbbVie, ABT-199, B cell lymphomas

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Lost in the fanfare surrounding the BTK inhibitor Ibrutinib and the PI3Kdelta inhibitor Idelalisib at this year’s American Society of Clinical Oncology meeting (ASCO 2013) was some rather stunning data from AbbVie on their Bcl-2 selective inhibitor ABT-199.
ABT-199 binds to Bcl-2 in such a manner as to prevent this protein from interacting with pro-apoptotic proteins such as BAX and BID, thereby allowing them to attach to the mitochondrial membrane, induce cytochrome-c release and trigger apoptotic cell death. Tumors disable the Bcl-2 pathway in a number of clever ways. Many tumor types delete p53, a protein that normally up-regulates expression of BAX and BID and down-regulates expression of Bcl-2 and related proteins (BclxL, Mcl-1, Bcl-w, etc). Tumors with this deletion phenotype are termed 17p(del) referring to the site of chromosomal alteration. Such tumors are generally very aggressive, resistant to chemotherapy and radiation, and associated with poor prognosis.
B cell lymphomas constitute a diverse collection of lymphomas and some leukemias (the distinctions have become blurred). B cell lymphomas have historically been classified as Hodgkin lymphomas or the very diverse Non Hodgkin lymphomas (NHL). The term NHL is confusing as this covers chronic lymphocytic lymphoma (CLL), mantle cell lymphoma (MCL), diffuse large B cell lymphomas of 2 subtypes (DLBCL-ABC and DLBCL-GCB), indolent Non Hodgkin lymphoma (iNHL) and a host of other tumor types. A baffling mix of biology and acronyms, but simply put, all of these tumor types are derived from various stages of B cell development, and most require signaling through the B cell receptor (BCR) to survive. The BCR triggers proliferative and survival (anti-apoptotic) signals, and therefore Bcl-2 becomes a relevant target in NHL.
Not surprisingly, genetic evaluation of B cell lymphomas has revealed mutations in Bcl-2 or downstream of Bcl-2 that foster lymphoma cell survival. Examples include constitutive activation of Bcl-2 in follicular lymphoma (FL) and CLL, amplification of Bcl-2 in MCL, down-regulation of NOXA (another pro-apoptotic protein) and BIM (a protein that regulates Bcl-2 activity) in iNHL and CLL, and down-regulation of expression of the caspases, part of the apoptotic machinery triggered by mitochondrial cytochrome-c release, in CLL.
ABT-199 was developed as a follow-on to the earlier Abbott compound navitoclax (ABT-263). Navitoclax inhibited multiple Bcl-2 family members, including BclxL, and was associated with severe thrombocytopenia (platelet loss) in clinical trials. Bcl-xL is an obligate pro-survival protein for platelets and thrombocytopenia became a dose limiting toxicity in navitoclax clinical trials. ABT-199 has a much lower affinity for BclxL than for Bcl-2, and spares other proteins in this family, as shown in this data reproduced from a recent AbbVie paper (Souers et al. 2013. Nat Med 19: 202-210):
                                 TR-FRET Ki (nM)
                      Bcl-2    Bcl-xL    Mcl-1    Bcl-w
navitoclax       0.044    0.055      > 224     > 7
ABT-199      < 0.01     48          > 444     245
What is important to note here is the relative difference in potency of ABT-199 against Bcl-2 (less than 10 picomolar, an unbelievable potency number) vs 48nM against BclxL. Taken at face value this is a 4800 fold difference in target potency. As noted below however, the number may be deceiving given the drug exposure achieved in patients.
AbbVie presented several studies at ASCO, including their Phase 1b trial in CLL. What is striking about the data is the response rates, as these compare favorably with similar data shown recently for BTK inhibitors and PI3K inhibitors, from Gilead (Idelalisib), Infinity (IPI-145), Celgene (CC-292) and J&J (ibrutinib). A snapshot of results from the CLL trials is shown below.
drug 
ABT-199 
Ibrutinib 
CC-292 
Idelalisib 
IPI-145 
pathway 
Bcl-2
BTK
BTK
PI3Kd isoform
PI3Kd/g isoforms
Partial response (PR) 
65%
68%
40%      (n = 5)
39%
55%
Complete response (CR) 
18%
2%
0%
0%
0%
Overall response (OR = PR + CR) 
84%
71%
60% (n=5)
39%
55%
OR in 17p(del)
81%
68%
NA
NA
50%
The table is adapted from results presented at ASH 2012, ASCO 2013 and this year’s European Hematology Association meeting (EHA 2013), as generously posted on Twitter by @andybiotech. ABT-199 differentiates from the competing drugs in several critical ways. First the OR rate reached 84% and was not statistically different between CLL patients having or not having the p53 deletion, ie.17p(del). Second, the CR rate was 18%, meaning that this many patients absolutely cleared disease from the bloodstream, lymphatic fluid, and lymph nodes. In addition AbbVie stated at ASCO that in the CR group, 11% had complete recovery of the bone marrow and 7% had partial bone marrow recovery – these are responses that are not seen with BTK or PI3Kg/d or PI3Kd inhibitors.
So why did the fanfare around NHL treatment coming out of Chicago in May during ASCO 2013 not include ABT-199? The answer was toxicity, and this toxicity came in 2 distinct forms. One has been addressed recently, the other is somewhat complex.
Tumor Lysis Syndrome (TLS) is a drastic physiological response to the sudden and acute destruction of massive numbers of tumor cells, more or less simultaneously. The disgorging of massive quantities of intracellular material triggers acute physiologic response as the heart, kidney, spleen and other organs cope with a titanic overload of potassium, calcium, phosphate, and uric acid. Organs fail and circulation collapses the patient drops quickly toward death. ABT-199 caused this syndrome in the first 3 patients that were dosed, each having been given 200mg of drug. One died. Faced with this spectacular disaster AbbVie immediately halted all ABT-199 clinical trials. That was back in January or February of this year. So the update at the end of May was tempered by this ongoing toxicity issue, and what AbbVie had to say at that point didn’t help. Starting with a lower dose of 50 mg they had restarted all trials, and gotten the drug into 34 CLL patients. Three experienced TLS, 1 died, 1 lost renal function (acute renal failure, generally meaning a lifetime of dialysis or a transplant). In addition, other toxicities were present, as seen in the next table showing severe toxicities (grade 3+) in CLL clinical trials. URI: upper respiratory infection. NA: data not available
drug 
ABT-199 
Ibrutinib 
CC-292 
Idelalisib 
IPI-145 
pathway 
Bcl-2
BTK
BTK
PI3Kd isoform
PI3Kd/g isoforms
Infections 
2% (URI)
18% (pneumonia
NA
19% (pneumonia)
NA
Liver damage (AST/ALT) 
NA
NA
NA
4%
6%
thrombocytopenia 
11%
5%
0%
NA
NA
neutropenia 
38%
18%
18%
NA
26%
anemia 
7%
5%
9%
NA
0%
The table is adapted from results presented at ASH 2012, ASCO 2013 and EHA 2013, as generously posted on Twitter by @andybiotech.
Where really jumps out here is at the level of thrombocytopenia and neutropenia seen in patients receiving ABT-199. Its worth noting that patients taking any of these new drugs are already at risk for decreased cellularity due to chemotherapy, and so adding to this burden complicates their subsequent care. Neutropenia is a bona fide pathway toxicity as demonstrated by defective expression of Bcl-2 in Kostmann syndrome (severe congenital neutropenia) and so there is nothing to do about this but lower drug exposure, potentially at the expense of efficacy. An interesting question in this regard is whether the thrombocytopenia and anemia seen are due to residual inhibition of BclxL. If you look at the PK data presented from the CLL trial, its pretty clear the effective concentrations of drug are far in excess of what is needed to inhibit BclxL. Taking data presented by Seymour et al. at ASCO 2013, abstract #7018, its clear that the maximum concentration achieved after multiple doses (Cmax(ss)) is up to 2mg/ml, which is going to give low mM exposure. So, at Cmax and for some time thereafter, drug concentration exceeds that required to inhibit BclxL by as much as 50-fold. Whether the duration of inhibition is sufficient to induce thrombocytopenia and anemia in patients is not known.
Lets go back to TLS, as this is the real show-stopper. On their July 26, 2013 earnings call, AbbVie stated that the dosing regimen has been further modified (details not clear). AbbVie further stated “With regard to tumor lysis syndrome which is a direct consequence of the explicit potency of 199 we have been enrolling CLL patients with a revised dosing schedule where we start at a lower dose and ramp up at a more slow rate, and so far so good with regard to the patients that we have been treating under that new protocol.” It is beginning to look as if AbbVie is learning how to manage TLS, and therefore have the potential to get their drug back in the fast lane.
Why does all this matter? Selective Bcl-2 inhibition is a unique strategy and ABT-199 illustrates compelling activity. In the era of rapidly advancing combination therapy for NHL, this could be an important component of the evolving treatment paradigm. With a lower dose they will try to avoid TLS and perhaps blunt thrombocytopenia and neutropenia. In the near term this drug may play a prominent role in patients who are at high risk (17p(del) or who are refractory to other targeted therapies. More interestingly, Bcl-2 inhibition in combination therapy may be a breakthrough treatment paradigm, and in this regard, AbbVie is swinging for the fences with trials combining ABT-199 with R-CHOP (Rituxan + chemotherapy) in pursuit of achieving outright cures. Combine this with genetic profiling of Bcl-2 and related proteins across many tumor types, and you have a very interesting story. 

This is a drug to watch, and just, perhaps, to improve upon.
As always, stay tuned, and follow us on Twitter @PDRennert.