This was one of the largest phase I studies ever performed in oncology, over 400 patients, and with one of the two anti-PD1 antibodies, this one being pembrolizumab which is Merck’s PD1. There’s also a PD1 from BMS that has also been in trials. This study today showed both response rate, durability of response and one year survival rate for this group of patients and I think the take-home message is approximately 40% of patients have true dramatic tumour shrinkage with this single agent; about two- thirds of them are having some clinical benefit, meaning stable disease or better, and survival at one year was almost 70% which is extraordinary given a very low side effect profile.
If it’s not a silly question, the comparison between anti-PD1 monoclonal antibody therapy and ipilimumab is what?
They’re different checkpoint inhibitors. CTLA-4, ipilimumab, is earlier in the process, PD1 is later so theoretically PD1 should work better because the T-cells should be in the tumour microenvironment more and you are seeing that. Obviously they haven’t been directly compared yet, although those studies have been performed and we’re waiting for results, but it appears that PD1 has significantly more activity than ipilimumab and will likely replace it when it comes on the market as frontline therapy theoretically.
But you’re saying we have to watch this space with the PD1 results, it’s not final yet?
It’s not final yet, it’s in front of the FDA, it’s under breakthrough status and we expect these drugs will be on the market, hopefully, by the end of the year.