BioXcel Therapeutics has reported “promising” top-line data including an “encouraging” response rate in its phase 2 Keytruda combination clinical trial. What is promising and encouraging about the data? That remains under wraps, with the biotech opting against providing even a smidgen of information ahead of the presentation of the full data next month.
The phase 2 clinical trial tested BXCL701, an oral innate immune activator, in combination with Merck & Co.’s blockbuster checkpoint inhibitor Keytruda in people with small cell neuroendocrine metastatic castration-resistant prostate cancer (SCNC). BioXcel began studying the combination in light of evidence that BXCL701 may improve the effect of Keytruda in immunologically “cold” tumors by boosting levels of key proinflammatory cytokines and activating the inflammasome.
In an earlier interim analysis, BioXcel reported a 33% response rate in patients with SCNC, an aggressive form of prostate cancer. Most of the 15 people included in the interim analysis had previously received platinum chemotherapy. Now, the biotech has published an upbeat assessment of the full data without disclosing whether the trial hit its primary endpoint or sharing any results.
Vincent O’Neill, M.D., chief R&D officer at BioXcel’s wholly owned subsidiary OnkosXcel Therapeutics, set out the little the company has revealed—and what he thinks it means—in a statement on the study.
“We are pleased that BXCL701 in combination with pembrolizumab has demonstrated an encouraging response rate in this difficult-to-treat cancer with no currently approved FDA therapies,” O’Neill said. “BXCL701’s promising profile as an oral innate immune activator with a large safety dataset and novel mechanism of action ... reinforces our confidence in BXCL701’s potential to enable checkpoint inhibitor therapy in traditionally cold cancers.”
BioXcel will present the full data next month at the American Society of Clinical Oncology Genitourinary Cancers Symposium. The data drop will reveal the outcomes seen in the 28 evaluable SCNC patients in a clinical trial that used a composite response rate as its primary endpoint.