Pidilizumab (CT-011, aka CureTech's anti-PD1)...the other white meat? Not so much..anti-PD1 drug comparison via ASCO abstracts

Phase 2, multicenter, safety and efficacy study of pidilizumab in patients with metastatic melanoma
Abstract 9001, Atkins, Kudchadkar, Sznol, Sosman, et al

103 patients with measurable, Stage IV metastatic melanoma, clearly progressive were randomized to two dose levels.  Prior treatments and stabilized brain mets were allowed.  Had to be 6 weeks from prior ipi, but never having had PD-1/PD-L1/PD-L2 blockade.  Overall survival at 12 months = 64.5% with insignificant differences between dosages.  The overall response rate was only 5.9% (using irRC....Remember, that gives you a built in higher response than when using RECIST!!!) . Progression free survival 2.8 months for the best group.
Seriously, CureTech??? You and your researchers state "further studies of pidilizumab in melanoma patients are warranted".  Who are you kidding and who do you think you will get to participate???  Much love and hugs and appreciation to the ratties who already laid it on the line to demonstrate the grand 5.9% response rate and got screwed out of the use of any other anti-PD1 product until the expanded access programs opened. Thanks, Jonathan!!!  But, I think we're done!!!!

Comparing data between trials is very tricky between differences in drug administration, patient sample, statistics used, data examined, and questions posed.  But, just so that you can have some measure of comparison (there have been no head to head studies) here's a little review and breakdown of the reports.  MK-3475 first:

 Clinical efficacy and correlation with PD-P1 expression in patients with melanoma treated with anti-PD1 monoclonal antibody MK-3475
Abstract 3005,  Kefford, Ribas, Hamid, Robert, Daud, Wolchok, Joshua, Hodi, Weber, Patnaik, et al

135 melanoma patients were given MK-3475.  In patients with measurable disease, the overall response rate was 41%.  For comparison with the last article noted here:  PD-L1 expression was associated with improved overall response rate (51% vs 6%) and progression free survival (median 12 vs 3 months). 

Baseline tumor size as an independent prognostic factor for overall survival in patients with metastatic melanoma treated with the anti-PD1 monoclonal antibody MK-3475
Abstract 3015, Joseph, Schaap, Wolchok, Joshua, Ribas, Hodi, Hamid, Daud, Weber, et al.

365 patients with measurable melanoma were treated with MK-3475 and had a one year overall survival of 69%.

Nivo:

Updated survival, toxicity, and biomarker of nivolumab with/without peptide vaccine in patients naive to, or progressed on, ipilimumab
Abstract 3009, Weber, Kudchadkar, Gibney, et al.

105 patients given nivo, 12 mo overall survival = 65%.

Here's a new abstract out of ASCO for Nivo:


Long-term survival of ipi-naive patients with advanced melanoma treated with Nivolumab in a Phase I trial
Abstract 9002, Hodi, Sznol, Kluger, Topalian, Sosman, et al

107 melanoma patients were given nivo .Overall survival rates = 63% at 1 year, 48% at 2 years, and 41% at 3 years.  32% of patients had objective responses (per RECIST!!!!!)  In patients with PD-L1 positive (18) and negative tumors (23):  the median overall survival has not yet been reached for the positive group and was 12.5 months for the negative group.  The median progression free survival for the positive group = 9.1 months and for the negative group = 1.9 months.
This abstract does address a factor that this post is not really about, but lots of folks are very interested in...whether PD-L1 positive tumors respond better to anti-PD1 products.  It seems as though they did in this sample...but I think we are far from clear answers.  See above for the PD-L1 data from a MK-3475 trial I had already posted.

It seems to me that Nivo and Merck's 3475 are still pretty much neck and neck in the data...though you can find a little better this and a little better that, here and there, depending on the study. What remains absolutely clear is that CureTech's pidilizumab is not even close to having the same results!

Ratties are amazing folks.  love, c