Category Archives: Onyx Pharma

AML Therapeutics Part 3: Immunotherapy

Ryan Teague and Justine Kline recently put together a nice review of immune evasion in acute myeloid leukemia (AML). The open access paper is available online (http://www.ncbi.nlm.nih.gov/pubmed/24353898). These authors have particular interest in tumor escape from immune surveillance by two interesting mechanisms. The first is termed T cell exhaustion, and refers to a non-responsive state induced in CD8+ (cytotoxic) T cells. The second is immune suppression, mediated by TGFbeta and regulatory T cells (Tregs). Other means used by tumor cells to avoid the immune system include deactivation by co-opting signals that directly shut down immune responses, such as PD-1 and other signaling mechanisms.

Why the interest in immunotherapy for such an aggressive cancer? There are a number of good reasons. First I think it is fair to state that targeted therapeutics (small molecule drugs) and antibodies (mAbs, ADCs, bispecifics) have yet to achieve a breakthrough in AML. The best of these drugs, even in combination, are only modestly effective. The second reason, implicitly recognized by the T cell engaging bispecific antibodies (BiTEs, DARTs) and by the still nascent CAR-T cell engineering technology, is that there is evidence to suggest that AML can be controlled by an effective immune response. This evidence comes from the leukemia transplantation field. As Teague and Kline state:

“Treatment with modern chemotherapy regimens often induces complete remission, but a majority of patients will ultimately relapse … it has been recognized that allogeneic stem cell transplantation can be curative for some patients with AML … derived from the so-called graft-versus-leukemia effect thought to result … Unfortunately, only a minority of patients with AML are candidates for this procedure.”

Those who are familiar with allogeneic SCT will further recognize that this is a risky procedure that can outright fail. So, are there safer or more direct ways to harness an anti-tumor immune response?

Novel therapeutics developed to stimulate anti-tumor immunity include the CTLA4 antagonist mAb, ipilimumab (Vervoytm; Bristol Myers Squibb (BMS)), approved for use in refractory or non-resectable melanoma. BMS is also developing the anti-PD1 mAb nivolumab, and combination trials with ipilimumab are underway. Other anti-PD1 and anti-PDL1 antibodies in advanced development for a variety of tumor types include MK-3475, submitted last month for FDA approval for the treatment of advanced melanoma, MPDL3280A (Roche), MEDI4736 (Astra Zeneca), and others. These are critically important therapeutics in hematological cancer and solid tumors. The potential breadth of applications is illustrated by the announcement last week the Merck will seek collaborative partnerships to develop MK-3475 in combination therapies. Merck will partner with Pfizer to investigate combination therapy in a phase 2 renal cell carcinoma (RCC) trial with the VEGFR inhibitor axitinib (Inlytatm). Merck will also partner with Pfizer for a phase 1 trial(s) using MK-3475 with the agonist anti-41BB antibody PF-2566, in multiple cancers. Readers will note that 41BB signaling is a critical component of the CAR-T T cell engineering technology. The collaboration with Incyte is also a dual-immunotherapy approach, as MK-3475 will be combined with INCB24360, an IDO inhibitor, in a phase 1 non-small cell lung cancer (NSCLC) trial. IDO is secreted by tumor cells, is a mediator of T regulatory T cell activity, and in AML is associated with poor prognosis. With Amgen, MK-3475 will be used in combination with the oncolytic viral therapeutic T-VEC, which induces tumor cell death and stimulates anti-tumor immunity.

The point of all this is to illustrate that for difficult cancers – melanoma, RCC, NSCLC – its not going to be easy, and combinations of novel therapeutics will have to be utilized. AML is a very difficult cancer. With this in mind we can look at the state of immunotherapy drug development in AML.

The Teague and Klein review goes into considerable detail on this subject, so we’ll just hit a few highlights and then see if we can update the storyline. A point the review makes that I didn’t fully appreciate is that AML tumor cells (and many others) can downregulate MHC Class I and II, making the tumor cells difficult for the immune system to recognize in the context of allogeneic SCT. This fundamental type of immune evasion may be difficult to circumvent. Other mechanisms of immune evasion used by AML include expression of PD-1L on the tumor cells, which effectively shuts down tumor infiltrating T cells that express PD-1, the PD-L1 receptor and mediator of a potent signaling response that downregulates T cell activity. AML tumor cells also express B7 family proteins B7-1 and B7-2,that bind to CTLA4, another downregulatory receptor. Clinical trials enrolling AML patients for treatment with therapeutics such as ipilimumab, nivolumab etc are described in the review. Its sufficient to point out that the effort to use these therapeutics for AML is in its very earliest stages.

A few recent observations point to other immune evasion strategies that night be productively targeted in AML.

Several preclinical studies have identified co-expression of TIM-3 and PD-1 as markers of CD8+ T cell “exhaustion”, and have likewise identified PD-L1 and galectin-9 (a putative TIM-3 ligand) on AML patient cells. TIM-3 is yet another receptor on T cells that mediates downregulation of T cell activity. Other markers of AML cells from patients were recently described (https://ash.confex.com/ash/2013/webprogram/Paper56968.html).

Relevant proteins included B7-2 (CD86), B7-H3 (CD276) and PD-L1. Patients with very high expression of both B7-2 and PD-L1 had worse overall and relapse free survival. HVEM, a receptor for several critical immune proteins including LIGHT, CD160, and BTLA, was expressed on a subtype of AML with relatively good prognosis. The author’s conclude ” that the profile of immune checkpoint molecules … correlates with molecular disease characteristics in AML and may even possess prognostic information, especially for relapse … (and) as therapeutic targets with respect to boosting anti-leukemic immune responses.”

An example of such an approach is provided by Innate Pharma, which is developing an anti-KIR antibody, lirilumab. KIR negatively regulates NK cell anti-tumor activity. A phase 1 trial in AML is continuing                             (https://ash.confex.com/ash/2013/webprogram/Paper59174.html). Preclinical data support the use of this mAb in combination with the cytotoxic anti-CD20 mAb rituximab in lymphoma. One might envision a similar approach using a cytotoxic mAb targeting AML such as the anti-CD33 mAbs discussed in part 2. Another possibility are the anti-CD38 mAbs. Second generation CD38 mAbs with improved cytotoxic activity are under intensive development for multiple myeloma by Sanofi (mAb SAR650984), Jannsen (daratumumab aka HuMax CD38) and MorphoSys (mAb MOR03087).

Another example is CoStim Pharma, bought today by Novartis. In their portfolio are novel immunotherapeutic mAbs, including TIM-3 antagonist mAbs. Novartis is moving quickly here to beef up its immunotherapeutic pipeline, which it can now develop in parallel with the U Penn CAR-T technology. Another local, private immunotherapy company is Jounce Therapeutics.

As we have also seen in parts 1 and 2, drug development for AML lags significantly behind other leukemias, lymphomas, myelomas, and the like. However, targeted therapeutics such as the tyrosine kinase inhibitor sorafenib, HDAC inhibitors vorinostat and panobinostat, and proteosome inhibitors bortezomib and carfilzomib hold some promise. The FLT3 and c-Kit targeting agents seem less likely to provide meaningful long-term benefit, although we’ll see what the combo trials brings. While it is too early to assess the CAR-T technology, the bispecific modalities, or immunotherapies in AML, the cytotoxic mAbs and ADCs should have a prominent role in controlling this aggressive disease.

We asked in Part 1 who the winners would be in 5 years. Looking over the landscape of therapeutics its pretty clear that winning will require collaboration among companies. With that said those companies with the biggest concentration of effort in AML include Merck, Onyx, Novartis, Amgen and perhaps Seattle Genetics. Given their past successes we can be hopeful that several of these companies will succeed in establishing breakthrough treatments for AML. In the end, patients should benefit the most from all of this activity. Perhaps stockholders will also benefit. With this in mind we note that Onyx probably has the most to gain (or lose) in this indication.

 stay tuned.

ANTICIPATING NEW THERAPEUTICS AND FORECASTING TREATMENT TRENDS FOR ACUTE MYELOID LEUKEMIA – PART 1

 by Paul D Rennert, February 11, 2014

In looking at Acute Myeloid Leukemia (AML) we see a cancer field right on the cusp of change in clinical practice. Standard of care chemotherapy regimens and stem cell transplantation protocols have proven to be of limited utility, especially in older patients. However, potentially big advances in care are being made, with exciting news coming out regularly. As we move toward the spring Medical Conference season, we felt an overview of this rapidly evolving area of oncology would be timely.

AML is a rapidly growing cancer of myeloid lineage cells that proliferate in the bone marrow and interfere with normal hematopoiesis. AML typically arises in the context of defined genetic mutations. For example, translocations of chromosome 16 disrupt RUNX1 gene activity and are one of the several underlying causes of Core Binding Factor AML. CBF-AML). Since RUNX1 regulates the transcription of many genes, the effect of its disruption is complex. CBF-AML patients are generally responsive to chemotherapy initially, although up to half of these patients will relapse over time due to additional genetic mutations.

Mutation of the FLT3 protein is the most common genetic abnormality in AML, found in about 30% of patients. This is a genetic characteristic associated with poor prognosis. The most common FLT3 mutation, FLT3-ILD, is caused by an tandem duplication within the coding region of the gene. The resulting protein drives hyper-signaling and oncogenic cell responses. Mutations that change the active site of the protein, causing unregulated phosphorylation, have also been described. Mutations in the receptor tyrosine kinase c-Kit are also associated with oncogenic signaling in AML. Both of these pathways cause mutiple downstream effector pathways to be activated. The JAK2 mutations, commonly see in myelofibrosis and other myeloproliferative disorders, are rare in AML but when characterized can potentially be treated with Jak2 inhibitors.

According to a recent market research analysis                           (http://www.transparencymarketresearch.com/acute-myeloid-leukemia-therapeutics-market.html) a total of 62,226 new cases of Acute Myeloid Leukemia (AML) were recorded in 2010, with 95,000 predicted new cases for 2015 and nearly 130,000 predicted new cases in 2020. Note that as of February 2014 approved agents for AML remain limited to chemotherapeutics (http://www.cancer.gov/cancertopics/druginfo/leukemia#dal2). Despite the lack of new targeted drugs, the AML therapeutics market was nearly 240 MM USD in 2011. At the current rate of growth the AML market could reach over 700 MM USD by 2018. These numbers are based on the analysis of future AML drugs growing at a 17% compound annual growth rate from through 2018.

Numbers like these are continuing to drive intensive research into effective, novel therapies for AML. It only helps that in many cases such therapeutics find use in other hematopoietic diseases such as Chronic Myeloid Leukemia (CML) and in the B cell lymphomas, including Hodgkin’s Lymphoma and the non-Hodgkin’s Lymphomas (NHL).

 There is obvious unmet medical need for effective therapies in AML since this is a disease characterized by quick relapse after therapy with grim survival statistics. In some older patients, survival is as little as 1-1.5 years despite first and second line treatment regimens.

What’s exciting from the drug development and biotech investment perspectives is that the AML treatment landscape is advancing simultaneously across therapeutic modalities. This rapidly changing landscape give us a chance to look at targeted small molecule drugs, monoclonal antibodies (naked, bi-specific, radiolabelled, immunotherapeutic, ADC), targeted T cells and other novel technologies.

 We can then ask ourselves: who will the winners be in 5 years?

 A) Targeted small molecule drugs.

Lets just be clear upfront that the goal of these targeted therapies is to get patients who have relapsed, or are refractory to chemotherapy, to a complete response (CR) with minimal residual disease (MRD) so they can qualify for an allogeneic stem cell transplant (SCT). That’s a lot of acronyms but what this is really saying is that for most patients the goal is a modest one – we are not asking for a durable remission, at least not yet.

 A variety of established drugs are being tested in AML. Also, the identification of oncogenic mutations in FLT3 and cKIT has driven interest in developing new tyrosine kinases inhibitors (TKIs) for AML.

 Sorafenib (NexavarTM; Bayer and Onyx) is a dual targeting drug that blocks RAF signaling (and therefore the MEK>ERK signaling) and also the growth factor receptor tyrosine kinases VEGFR and PDGFR. The NCI is running a large phase 3 trial enrolling new onset pediatric AML patients (NCT01371981) with sorafenib being given in combination with various chemo regimens.  Bayer and Onyx are running several earlier phase AML trials. An interesting phase 1 trial in patients 18 or older combines sorafenib with plerixafor and G-CSF (NCT00943943). The idea here is to have the CXCR4 blocker (plerixafor) and the growth factor (G-CSF) flush tumor cells, and also tumor stem cells, from the bone marrow and lymph nodes so that they are more sensitive to sorafenib treatment. This trial is co-sponsored by Genzyme/Sanofi, which owns plerixafor.

Another interesting trial is the Phase 1/2 study of the combination of sorafenib, with vorinostat, and bortezomib (NCT01534260). Here we have a proteasome inhibitor and an HDAC inhibitor added to growth factor and signaling inhibition provided by sorafenib. This potent combination is being used in patients with a poor genetic risk profile, including FLT3-ILD positive tumors. This study is co-sponsored by Bayer/Onyx, Millennium/Takeda and Merck Sharp & Dohme Corp.

Bristol Myers Squibb is running an interesting trial (NCT01620216) in which AML and acute lymphocytic leukemia (ALL) patient samples are analyzed for sensitivity to drug treatment ex vivo, after a period on drug in the trial, as follows:

“An in vitro kinase inhibitor assay will be used to determine the sensitivity of primary leukemic cells to four kinase inhibitors/drugs:

Drug: Sunitinib, 50 milligrams (mg) qd, with or without food, for 4 weeks

Drug: Dasatinib, 100 mg qd…possible escalation to 140 mg qd for 28 days

Drug: Nilotinib, 400 mg twice daily for 28 days

Drug: Sorafenib, 400 mg (2 tablets) orally twice daily without food for 28 days

Drug: Ponatinib, 45 mg dose once per day

Sunitinib (Sutenttm; Pfizer) makes sense as a pan-growth factor receptor inhibitor; dasatinib (Spryceltm; Bristol Myers Squibb) is a Src and c-Kit inhibitor and is a reasonable choice for AML; nilotinib (Tasignatm; Novartis) is a pretty specific Bcr-Abl kinase inhibitor and is probably only being used for the ALL population – and even there only 25% of ALL patients carry this translocation; sorafenib we discussed earlier; ponatinib (Iclusigtm; Ariad) has a grab bag reactivity profile, hitting the BCL-ABL kinase, FLT3, RET, c-KIT and the FGFR, PDGFR and VEGFR growth factor receptor kinases. This is a dangerous drug, with a very narrow FDA approval in CML, and I suspect enrollment in this little exploratory trial will be stopped if possible.

If I had to guess I would say that this rather odd trial design has several goals. One is to look for signs of efficacy, although a month is pretty short duration. One might also look for patterns of resistance to therapy, which would be very interesting. Since this is BMY, I’d be surprised if they weren’t also looking at cell surface markers for possible immunotherapy treatment – more on this subject later.

Results from a dasatinib trial in CBF-AML were recently presented at the American Society of Hematology (ASH) conference (Abstract #357). Dasatinib was added to induction and consolidation chemotherapy in newly diagnosed AML patients. Unlike the rrAML population, the CBF-AML population can experience sustained periods of remission prior to relapsing, especially in younger patients. Since some of the relapses are driven by gain of function mutations in c-Kit, dasatinib should prevent at least those clones from becoming established. Early results looked good but longer term data are needed to see if this regimen will remain effective.

Imatinib (Gleevectm; Novartis) another Bcr-Abl, c-Kit and PDGF-R inhibitor, has been tested in multiple AML trials, but the results have not led to approval for use in AML. An interesting trial of the cytotoxic/immunomodulatory agent lenolidomide (Revlimidtm; Celgene) plus chemotherapy is being run by the NCI (NCT01246622). Lenolidomide has been approved for the treatment of a different bone marrow resident cancer, multiple myeloma (MM).

Anyway there is a lot of similar clinical trial work being done – using approved drugs in this new indication and looking for efficacy. This is ultimately good both for patients and the drug development companies.

Lets move on to some newer drugs in the pipeline. The FLT3 inhibitors give us a sense of the difficulty here, with low response rates as monotherapies.

Quizartinib (Ambit Biosciences; AMBI) remains stuck between phase 2 and 3 for relapsed/refractory (rr) AML. This drug is a FLT3 inhibitor with a somewhat tortured history, having been partnered for a time with Astellas, then returned, then running nicely in the clinic before running into disagreement with the FDA over approvable endpoints and safe dosage. In early December the company announced it would have to run a phase 3, likely with lower starting doses, in order to obtain FDA approval. Investors were hoping the company could file on its phase 2 trials. Notably, later in December Ambit showcased its’ quizartinib data from the FLT3-ILD rrAML trial, in which a 50% response rate (50% or greater reduction in leukemic blast cells) was reported with relatively low doses of drug. Unfortunately, it will be a while yet before more news becomes available about this drug.

In the meantime heavy hitter Novartis is already in phase 3 with its’ FLT3 and Protein Kinase C inhibitor midostaurin. The phase 3 in newly diagnosed patients is being run by the NCI (our tax dollars at work), along with The Alliance for Clinical Trials in Oncology and the Cancer and Leukemia Group (NCT00651261). A trial of midostaurin administered with or without bortezomib in adult rrAML patients is being run by Novartis and Millennium/Takeda (NCT01174888). Preliminary results were presented at ASH (abstract #3966). While response rates were impressive the toxicity was extreme, and this seemed to be due to the bortezomib dose, which was adjusted. Phase 2 trials in adult patients who carry c-KIt, FLT3-ILD, and various other mutation or cytogenetic markers are also underway (NCT01830361, NCT01846624). A phase 2b midostaurin  monotherapy study published several years ago showed modest improvement in AML patients with mutated FLT3; this study recognized the need for combination therapy to improve the clinical response (http://www.ncbi.nlm.nih.gov/pubmed/20733134).

Another FLT3 inhibitor, lestaurtinib, is the subject of 2 NCI sponsored trials in pediatric ALL/AML but drug development of this agent seems to have stalled when Teva bought Cephalon. Another FLT3 inhibitor is PLX3397 (Plexxikon) which has activity against  KIT, CSF1R and FLT3. This drug is in a phase 1/2 trial in adult rrAML (NCT01349049).

One of the major challenges for FLT3 inhibitors is breadth of action. These inhibitors work best on patients who have mutated FLT3 and are less effective in patients with normal FLT3. Also, secondary mutations have already been discovered in response to FLT3 inhibition. Specifically, in those patients who have mutations in the active site of the kinase, so-called gatekeeper mutations arise, conferring resistance to the drug.

A dominant theme in recent drug development for AML has been built on the observation that proteasome inhibitors can impact cancers of the bone marrow. Disruption of proteasome activity blocks a wide spectrum of cellular activities, and is particularly effective against rapidly dividing cells (like leukemic blasts) but also relatively quiescent tumor stem cells, that require specific proteasome-dependent signaling pathways (e.g. NK-kB). Bortezomib (Velcadetm, Millennium/Takeda) has shown activity in older patients when combined with chemotherapy. A phase 3 combination trial with sorafenib in newly diagnosed AML patients is underway, sponsored by the NCI (NCT01371981).

Carfilzomib (Onyx Pharmaceuticals) is in an early stage trial for AML, along with extensive trials in MM, B cell lymphomas, etc. The drug is furthest along in MM, now in phase 3 (NCT01568866). Early reports so far have suggested that this drug has an activity profile similar to bortezomib, but may have a better safety profile. This is an interesting drug (and company) to watch. They have a second generation oral version of carfilizomib, oprozomib, in phase 1 MM trials. Millennium/Takeda are developing ixazomib in MM and lymphomas. An AML trial is listed but not yet recruiting.

A third theme that we can follow in AML therapeutic drug development is the use of drugs that impact epigenetic gene regulation. Because AML is driven by genetic translocations, gene regulation at the level of chromatin structure is disrupted. There are two processes at work here that can be targeted. One is the aberrant methylation of CpG islands in gene promoter regions, which can be targeted by DNA methyltransferase inhibitors. The second is changes in the conformation of chromatin caused by dysregulated histone acetylation. This process can be therapeutically targeted using histone deacetylase [HDAC] inhibitors.

The HDAC inhibitor vorinostat (Zolinzatm, Merck) has been extensively studied in AML, and is currently in a phase 3 trial with chemotherapy for young patients with newly diagnosed disease (NCI; NCT01802333). Vorinostat monotherapy was generally ineffective, but combination with chemo agents proved much more potent. As detailed at ASH in December (Abstract #2684), newly diagnosed and rrAML patients were enrolled in a phase 2 expansion study. Of 75 patients, 57 patients achieved CR, and 7 achieved CR with incomplete platelet recovery (CRp), for an overall response rate of 85 percent. Median overall survival was 82 weeks and median event free survival was 47 weeks. For patients with the high-risk Flt-3 ITD mutation the 10/11 achieved CR and 1/11 CRp. The ORR = 100% in these patients. Their median overall survival was 91 weeks and median event free survival was 66 weeks. About 25% of the total patients in CR received SCT.

Other combination trials include the sorafenib trial mentioned above, and a trial in combination with antibody therapy (gemtuzumab ozogamicin) for rrAML (NCI; NCT00895934). This trial reported early results at ASH (Abstract #3936). The response rates ere encouraging and about 20% of patients obtained durable remission. There were significant toxicity issues. This drug is very likely to play a critical role in the evolution of combination therapy for AML. We’ll discuss antibody therapies further in Part 2.

Other important HDAC inhibitors in development for AML is panobinostat (Novartis). What’s interesting about the development campaign with this drug is the pairing in multiple trials with 5-azacitidine, a DNA methytransferase inhibitor. In such settings two modes of epigenetic regulation are being targeted simultaneously. One of these studies published findings last month                                 (http://www.nature.com/bcj/journal/v4/n1/full/bcj201368a.html) and demonstrated good tolerability and reasonable response rates. Clearly, this combination should move forward in the context of chemotherapy or other drugs. Of note the DNA methyltransferase inhibitor decitabine (Dacogentm, MGI Pharma) is already approved for AML. There was also a presentation on the HDAC inhibitor entinostat (Syndax Inc) with 5-azacitidine in myeloid neoplasia (Abstract #2777), and there are several clinical trials listed for AML, however this drug is mainly being used in solid tumor trials.

Other interesting drugs in this area include alisertib, an Aurora A kinase inhibitor (Millennium/Takeda) being tested extensively in B and T cell lymphomas and in solid tumors. There are several AML trials including a phase 2 trial completed by MLMN (NCT00830518). Selinexor, (Karyopharm) a selective inhibitor of nuclear export, in in phase 1 trial for advanced AML. Abbvie’s Bcl2 inhibitor ABT-199 is also in an AML trial.

If we take a step back we can appreciate that in small molecule development Novartis, Merck and Onyx are placing big bets in this therapeutic area. We’ll sort out the best looking therapeutics as we dig in a little deeper.

In Part 2 we’ll take a look at the biologics landscape, and begin to draw the bigger picture.

Oncology drug development questions for 2014: Combination therapies for B cell lymphoma

Part 1 – Ibrutinib and the development of combination therapies for B cell lymphoma

For physicians, patients, investors etc, major medical conferences are a way to check in on the progress of a company’s drugs in the context of the medical communities response to the data, i.e. the buzz. Negative buzz is generally pretty straightforward, reflecting poor results or unexpected toxicity in a clinical trial. Positive buzz should be (and often isn’t) more nuanced, as positive data, while great to see, need to be placed into the context of evolving clinical practice and the ever-present competition for patients. Results, positive or negative, need to be vetted for robustness: clinical trial stage, sample size, design; endpoint design; therapeutic window (the dose range between efficacy and toxicity); and duration of response.

Last year saw extraordinary advances in the treatment of B cell lymphoma, particularly the Non-Hodgkin Lymphomas (NHL) that include well known cancers like Chronic Lymphocytic Leukemia (CLL), Mantle Cell Lymphoma (MCL), indolent NHL (iNHL) and many others. This advances included small molecule therapeutics that target critical drivers of lymphoma cell proliferation and survival, novel antibodies (“naked”, enhanced, payload carrying), ex vivo modified patient T cells that attack lymphomas upon reinjection, and a variety of other modalities. It was interesting to see that the companies getting the most buzz varied during the year, with different companies “winning” different conferences. Be assured that in this context, winning reflects wins for the stock price! Winning in the medical marketplace is a whole different story.

With the medical marketplace in mind, a reasonable question for 2014 pops up when you step back and look at the breadth of the B cell lymphoma therapeutic landscape.

How will biopharmaceutical companies, physicians, and payers develop and use combinations of these therapies?

Lets think about the possible combinations. The most obvious are those that we are already seeing widely used, such as the combination of a small molecule inhibitor with a tumor-targeting antibody. One example is the combination of ibrutinib, a BTK inhibitor, and rituximab, an anti-CD20 monoclonal antibody. Ibrutinib was approved for treatment of relapsed/treatment refractory (rr) MCL in November 2013 under the brand name Imbruvica, and approval for rrCLL is expected soon (these indications were filed for approval together, in August 2013). Patients with relapsed/refractory small lymphocytic lymphoma (SLL) were included in the CLL arm of the clinical trial.

CLL is a good example of the power of combination therapy. Rituximab monotherapy in rrCLL/SLL produced overall response rates (ORR) in the range of 55% and a complete response rate (CR) of somewhere under 10%, depending on the trial. Note here that ORR and CR refer to assessments of tumor burden at a specific and predetermined time after treatment is initiated. A CR does not indicate a cure but rather is a measure of the degree of efficacy. The ORR and CR measurements are most meaningful when presented in the context of duration of response (DOR) or in the context of progression-free survival (PFS) or overall survival (OS).

Monotherapy of rrCLL/SLL with ibrutinib produced ORRs ranging from 70-80%, with CRs ranging from 0 – 10%. Duration of response was good, and there was a measurable impact on PFS. There are different classes of rrCLL patients, based on cytogenetic status. High risk CLL patients commonly carry a deletion on chromosome 17 (del17p) and/or other abnormalities. Such mutations predict poor prognosis for these patients. Last April, the FDA granted Ibrutinib Breakthrough Therapy Designation for high-risk rrCLL/SLL del17p patients based on achievement of a 50% ORR in these patients when given ibrutinib monotherapy.

Now to the combination of ibrutinib and rituximab (and a chemo agent, bendamustine). As discussed in earlier coverage of the American Society of Hematology Annual Meeting (ASH), linked here, treatment of high-risk CLL patients with the combination therapy produced an ORR of 95%, with 78% maintaining response through 18 months. While only 10% of the responses were designated CR, the long duration of the partial responses (PR) was a dramatic result.

The cost of Rituxan treatment for B cell lymphoma is generally quoted at ~10K/month but billed to insurance at about 5K monthly, so we are somewhere between 60-120K per year per patient in the US. Imbruvica will cost 130K per year per patient in the US. Note here that neither therapy, given alone, is considered curative. We don’t know yet what the durable remission rate will be for the combination therapy, where we define durable remission as no detectable disease (in the blood, lymph nodes, bone marrow) without maintenance therapy. Curative treatment means no disease in a patient who no longer requires drugs.

So it’s fair to say that these combination therapies will be very expensive and may need to be used for a long time. Given the current climate of cost control, especially outside of the US, what are companies doing to anticipate eventual pushback on premium pricing?

Just a quick reminder that Imbruvica (ibrutinib) is a Pharmacyclics/Johnson&Johnson (J&J) product and the Rituxan is a Roche product and further, that Roche has a next generation anti-CD20 antibody, obinutuzumab, recently approved for the treatment of CLL (including as first line treatment), under the brand name Gazyva. This antibody given in combination with a cheap chemotherapy agent, chlorambucil, produced an ORR = 78% and a CR of 28% in the phase 3 trial. This antibody was significantly better than Rituxan (rituximab) plus chlorambucil in the same clinical trial (ORR = 65%, CR = 7%). The trial was done in rrCLL patients including high-risk patients defined as del17p.

Another anti-CD20 antibody, ofatumumab from GSK, has been approved for second-line use in rrCLL. This drug, priced at 120K yearly, ran into reimbursement pressure in Europe and the UK as not showing sufficient benefit to justify the price. This is a hint of price pressures to come.

This is where I think things get really interesting. I spent some quality time on clinicaltrials.gov, trying to understand how companies competing in the B cell lymphoma space are looking ahead, the assumption being that one can do this by looking at the trials planned or underway for the top tier drugs. Many of the oral drugs in advanced development for B cell lymphomas are reviewed here.

Nearly all advanced oral drugs for B cell lymphoma have trials underway or planned with an anti-CD20 antibody. Most of these trials are done with rituximab, probably just reflecting the wide availability of this antibody. Perhaps some companies are sticking with rituximab in the belief that generic biosimilar forms of this antibody will become available in Europe (where it is now off-patent) and in the US (where patent protection expires in 2018), which may make combination therapy more widely available. The rituximab trials are not done in collaboration with Roche, with one notable exception which we will get to later.

There are 11 clinical trials listed as active that include ibrutinib with rituximab either alone or with various other agents. Some of these trials have already read out results:

TRIAL NUMBER
PHASE
DATE FILED
IBRUTINIB WITH
INDICATION
NCT01980654210/24/2013rituximabuntreated FL
NCT0188056726/4/2013rituximabrrMCL
NCT0152051921/25/2012rituximabhigh risk CLL, SCL
NCT0161109035/15/2012rituximab/bendamustinerrCLL, rrSCL
NCT0177684031/24/2013rituximab/bendamustineuntreated MCL
NCT01479842111/1/2011rituximab/bendamustinerr DLBCL,MCL,iNHL
NCT0185575035/14/2013R-CHOPDLBCL-ABC
NCT0188687236/24/2013noneuntreated CLL
rituximab
v rituximab/bendamustine
NCT01974440310/28/2013R-CHOPrr iNHL
v rituximab/bendamustine
NCT0188685916/24/2013lenalidomiderrCLL, rrSCL
NCT0182956814/9/2013lenalidomide & rituximabrrFL
NCT0195549919/27/2013lenalidomide & rituximabrr iNHL

Note that FL is follicular lymphoma and DLBCL is diffuse large B cell lymphoma. DLBCL-ABC is a subtype. These are all types of B cell lymphomas. R-CHOP is rituximab plus a standard mixture of chemotherapeutic agents, and I may or may not have defined this correctly, suffice to say if it says CHOP then there is a potent mix of chemo being given; “v” means versus, that is, it is a comparator arm.

There are another seven or eight single agent ibrutinib trials also, but I did not include those here, so what we see all together is a full court press of clinical trials designed to show benefit of ibrutinib in multiple different B cell lymphomas, as first line or second line therapy. These trials will produce a tidal wave of data that, if positive, will by their sheer volume place ibrutinib at the top of the heap of B cell lymphoma oral agents. So, yes, I’m betting on Pharmacyclics (stock symbol PCYC) and J&J to win the marketplace, at least for the near term.

Ibrutinib development does not stop there. There are three trials with lenalidomide, also known as Revlimid, approved as second line therapy for multiple myeloma (MM). A monotherapy trial of lenalidomide in CLL was halted last year due to an increase in deaths seen in the active arm. Even at a reduced dose (I’m guessing here) the use of this agent plus ibrutinib plus rituximab seems risky. Also, the drug is owned by Celgene. So why conduct trials with lenalidomide at all? The answer to that question will be found in the list of clinical trials for CC-292, Celgene’s BTK inhibitor under development for B cell lymphoma.

But just to finish with ibrutinib. Here are the rest of the active clinical trials I could find:

TRIAL NUMBER
PHASE
DATE FILED
IBRUTINIB WITH
INDICATION
NCT020131281,212/11/2013ublituximabCLL, MCL
NCT0157870734/11/2012v ofatumumabrrCLL
NCT012177491,210/7/2010ofatumumabCLL
NCT01478581211/18/2011nonerrMM
NCT0184172321/24/2013noner Hairy Cell leukemia
NCT019627921,29/27/2013carfilzomibMM

Ublituximab is a new anti-CD20 antibidy from TG Therapeutics and the clinical trial is being run by that company, not by J&J/PCYC. In contrast the ofatumumab trials, which are “active but not recruiting” are sponsored by Pharmacyclics.

Finally, just some tidbits. Ibrutinib presentations recently have included studies in some interesting new indications, particularly MM. There are two MM trials shown here, the second one being run in collaboration with Onyx Pharmaceuticals, whose proteosome inhibitor carfilzomib, has been approved for treatment of rrMM under the name Kyprolis.

I suspect we will see many more such collaborative efforts as the field matures.

Next up we will look at the efforts of two of the compounds seeking to compete with ibrutinib, Gilead’s idelalisib and Celgene’s CC-292.

Stay tuned.