ISA Pharmaceuticals' cancer vaccine may have failed to improve the overall response rate in a phase 2 trial, but the Netherlands-based biotech is insistent that honing in on a subgroup of patients that it hopes will reap rewards in phase 3.
The candidate in question is a HPV16-directed therapeutic cancer vaccine dubbed ISA101b. The mid-stage trial enrolled 199 patients with recurrent/metastatic HPV16-positive oropharyngeal cancer who received either ISA101b and Regeneron’s anti-PD1 checkpoint inhibitor Libtayo, or Libtayo and placebo.
The primary endpoint was six months' overall response rate (ORR) across the entire population, which the study failed to hit. However, ISA was quick to try and claw back some positives from the results, pointing out that a “large subgroup of patients” who received the ISA101b regimen saw a doubling of the ORR from 26.7% to 51.9%.
Not to be held back by the topline fail, something of a trend in general cancer vaccine research, the biotech hailed the results as “the first time that the combination of a tumor-specific therapeutic vaccine and a checkpoint inhibitor has generated such high response rates, albeit in a predefined subpopulation of metastatic cancer patients.”
ISA was vague about the exact makeup of this subgroup, only revealing in the Nov. 12 release that they were “predefined based on a validated biomarker.” Still, the biotech will power ahead with a phase 3 study in this group, which it claimed “represent an important proportion of head and neck cancer patients and an attractive commercial opportunity.”
"In our OpcemISA study, ISA101b shows compelling results in a large, predefined subset of patients,” ISA CEO Gerben Moolhuizen said in the release. “This provides us with a clear development path to make ISA101b a treatment option for these patients."
Regeneron’s relationship with ISA dates back to 2017, and the big biotech increased its equity stake in ISA in 2020. As a result, Regeneron had an option to license ISA101b but ISA said in today’s release that its partner had now decided not to take on the asset.
“ISA is currently in discussions with potential partners with interest in ISA101b and ISA's technology platform in general,” it added.