Combination therapies for B cell lymphoma, part 2

Combination therapies for B cell lymphoma: CC-292 and idelalisib.

Lets begin by recapping where we were yesterday. We reviewed ibrutinib, the clear frontrunner in the race to bring new targeted oral therapies to B cell lymphoma physicians and patients. Ibrutinib is being developed by Pharmacyclics and Johnson & Johnson’s (JNJ) Janssen division, and was recently approved for the treatment of MCL. The drug is moving forward in many clinical trials spanning the B cell lymphoma space, and most of these trials are done in combination with other therapeutics, notably the antibody therapy rituximab (Rituxan). None of the trials are being run as collaborative efforts with other companies with one exception, a collaboration put in place with Onyx (now part of Amgen). None of the combinations are wholly owned by Pharmacyclics (PCYC) and JNJ. The interesting question of how best to tackle the cost of very expensive combo therapies in the oncology marketplace was raised.

Gilead (GILD) has developed the very exciting PI3Kdelta inhibitor, idelalisib (access to a recent review is here). Idelalisib data generated at lot of buzz at the American Society of Clinical Oncologists meeting (ASCO) and at ASH. While generally considered somewhat inferior to ibrutinib as a monotherapy, the phase 3 data in combination with rituximab was striking. The trial was run in rrCLL patients who had failed prior therapies (rituximab or chemo), so these are patients quickly running out of options. The ORR was 81%, but what was really impressive was the impact on PFS and OS. At 24 weeks twice as many patients were progression free in the idelalisib plus rituxumab arm (95%) versus the rituximab alone arm (46%). We’ll have to see how this therapy holds up, and we can expect interesting data at the 2014 conferences.

But back to our question for 2014 and beyond: how will combination therapies continue to develop for the treatment of lymphoma? Lets look at Gilead’s active clinical trials for idelalisib – note that some of these trials have already read out results.

Trial Number
date filed
NCT01732913311/14/2012rituximabrr iNHL
NCT0120393029/15/2010rituximabuntreated CLL, SCL
NCT01980875311/5/2013rituximabuntreated CLL
or chlorambucilÿ
NCT01732926311/14/2012bendamustine/rituximabrr iNHL
NCT01980888311/5/2013bendamustine/rituximabuntreated CLL
NCT0108804811/12/2010RituximabrrCLL or rrMCL or rr iNHL
Rituximab + Chlorambucil
Lenalidomide + Rituximab

At first glance this looks a lot like the list of trials listed for ibrutinib, and it is very similar. We see multiple combo trials with anti-CD20 mAbs (rituximab, ofatumumab), and several trials with Celgene’s lenalidomide (Revlimid), approved for MM. Again the choice of lenalidomide is interesting. The combination makes good sense biologically – lenalidomide should impact cells lodged in the bone marrow, where they would otherwise be resistant to anti-CD20 or idelalisib therapy. The question is how well is this combination therapy tolerated. The other interesting observation is that there are a fair number of trials in which the partner therapy is a chemotherapy (fludarabine, chlorambucil, bendamustine). Now these are all careful targeted to specific lymphomas in the last trial listed, NCT01088048, and you can look at the details here. I think this suggests that in addition to the high impact rituximab combinations, GILD is banking on seeing good efficacy in combination with standard chemotherapies. If so this will give the company an effective marketing and pricing edge.

Finally, and sensibly, we see a clinical trial in combination with Gilead’s own Syk inhibitor GS-9973. Gilead has advanced this inhibitor while also conducting a well publicized hunt for a BTK inhibitor to license, apparently without luck (and really, there just aren’t many good ones). The idea here is to knock out the Syk signaling to BTK, thus mimicking the effect of ibrutinib, in combination with eliminating PI3Kdelta signaling. If the combo is synergistic, and (importantly) well tolerated, GILD may be sitting on a unique therapeutic option. Again thinking of the marketplace, this could provide leverage with physicians and payers, although no one is suggesting that Gilead won’t price a combo as high as possible, as shown by the recent pricing of its HCV cocktail – and that drug at least can induce outright cures.

This brings us to Celgene, who is attempting to build combination therapies for lymphoma that it can control. Celgene is well behind ibrutinib in their development of CC-292, acquired with the Avila deal. Recently however they have adjusted the dosing schedule (to twice a day: bid) and are seeing reasonable ORRs between 55 – 67% depending on dose, as reported at ASH. The bid dosing regimens produced sustained responses through 7 months.

What is so interesting about the Celgene program is shown in the following table.

Trial Number
date filed
CC-292NCT017665831b10/29/2012lenalinomiderr NHL
CC-292NCT01732861111/14/2012lenalinomiderr CLL, SCL
CC-292NCT01744626112/5/2012rituximabrr CLL, SCL
AVL-292NCT0135193515/10/2011nonerr NHL, CLL, WG
lenalinomideNCT014006851,2April/May 2011bendamustine/rituximabCLL
lenalinomideNCT0193800139/5/2013rituximabrrNHL, rrFL
lenalinomideNCT0119957528/31/2010rituximabrr CLL
lenalinomideNCT0155677633/14/2012nonehigh risk CLL

What we see here is a nice focused effort on bringing forward CC-292 with perhaps lenalinomide. I don’t know the regulatory hurdles imposed since the withdrawal of lenalidomide from a CLL trial earlier this year (but please comment if you do), and so the issue may be moot, but the idea is a good one – to rationally develop combinations that are wholly owned.

We can make some predictions.

JNJ will buy a clinical stage compound suitable for further development with ibrutinib. This could be an antibody targeting B cell lymphoma antigens (CD20, CD22, CD19, etc) or another small molecule asset.

Celgene will make similar moves but may take assets at a slightly earlier stage, maybe IND ready or Phase 1.

Gilead will continue development of its Syk inhibitor, but I suspect will also license clinical stage assets in order to diversify around idelalisib.

Assuming success in the early stage studies in relapsed/refractory patient populations, Gilead will aggressively position idelalisib for use with chemo in treatment naive patients.

If you have different ideas feel free to send those along. Next there will be just a short take on Abbvie, as they are on a slightly different course.

stay tuned.