Immuneering has reported 94% overall survival (OS) at six months in first-line pancreatic cancer, emboldening the biotech to start planning a pivotal trial to support accelerated approval of its MEK inhibitor.
The data come from a phase 2a trial that tested atebimetinib in 34 patients. Participants received the MEK inhibitor with a modified form of the gemcitabine–nab-paclitaxel chemotherapy combination that is currently used to treat pancreatic cancer.
Lacking a control arm, Immuneering compared its survival data to a 2013 paper on the effectiveness of a full dose and schedule of the chemotherapy combination. The earlier trial found 67% of patients on the chemotherapy combination were alive after six months. The median OS was 8.5 months.
Immuneering’s trial is yet to reach median OS. Discussing the data on a call with investors, Immuneering CEO Ben Zeskind, Ph.D., gave a bullish assessment of the likelihood of survival rates staying high as the data mature.
“The vast majority of tumors are continuing to shrink,” Zeskind said. “This is not, we believe, the picture of a group of patients that are about to have, frankly, either progression events or ultimately survival events. We believe this is a picture of patients that are likely to continue to have excellent durability.”
Progression-free survival (PFS) was 72% on atebimetinib after six months versus 44% in the historical chemotherapy trial. Immuneering's trial was yet to reach the median PFS duration as of the data cutoff. The overall response rate was 39% compared with 23% in the historical control.
Durability and tolerability are the two pillars of Immuneering’s positioning for atebimetinib. Immuneering sees “a dramatic difference between [its] drug and the other things that are out there for the map kinase pathway” in terms of tolerability, Zeskind said.
For adverse events, an Immuneering presentation offered a comparison between the atebimetinib study and three pancreatic cancer pivotal trials for other drugs. Grade 3 or worse anemia was more common in the atebimetinib study than in those trials, but other adverse events were rarer.
Immuneering has identified the frequency of rashes, nausea, vomiting and diarrhea as areas in which its molecule may have advantages over other drugs that act on the map kinase pathway. One patient in the atebimetinib trial had grade 3 or worse vomiting. Nobody had grade 3 or worse diarrhea or nausea.
An analyst asked Zeskind how the atebimetinib data compare to the evidence for other drug candidates, including Revolution Medicines’ daraxonrasib. Zeskind said Revolution’s data are in second-line patients, adding that other companies have yet to show they can combine their molecules with chemotherapy. Even if rivals do present strong data, Zeskind believes Immuneering can still lead in the first-line space.
“If this continues to play out as it is, it really doesn't matter what else is out there. You really can't get much better than this. No one is going to be able to beat this if it continues as it is,” Zeskind said. “In the best-case scenario where you have multiple treatments, that all keep almost every pancreatic cancer patient alive ... it would come down to tolerability.”
Investors are unconvinced. The stock opened down 6% at $2.22. Immuneering has a market cap below $100 million and ended March with $35.9 million. The biotech said last month that its cash reserves will fund operations into next year.