Straight from a “late-breaking poster” at the annual meeting of the Association for the Advancement of Cancer Research going on in Washington, DC, comes data about BPX-101 another dendritic cell-based immunotherapeutic “vaccine” for the possible treatment of late-stage prostate cancer.
BPX-101 is in development by Bellicum Pharmaceuticals, Inc. At the poster presentation earlier today, the research team was able to announce interim Phase I/II data suggesting a correlation between dose-related variations in levels of inflammatory serum markers and measurable clinical responses in patients treated with BPX-101.
The Phase I/II trial was designed to assess the safety and the maximum tolerated dose or MTD of BPX-101 when administered every other week for six dose to patients with metastatic castration-resistant prostate cancer (CRPC). Data presented today are based on only 6 patients, but appear to show the following (according to the media release issued by Bellicum Pharmaceuticals):
The combination of BPX-101 and an activating agent (AP1903) is safe and well tolerated at low- and mid-level doses of BPX-101, with no signals for unexpected drug-related adverse events.
Clinical responses were observed within 12 weeks of initial treatment, in patients who received low- and mid-level dose cohorts.
4/6 patients achieved a maximal decrease in serum PSA levels of at least 10 percent from baseline (including the specific individual mentioned above, who achieved a maximal serum PSA decline approaching 50 percent).
5/6 patients experienced a significant increase in PSA doubling time (PSADT) by 12 weeks, including 2/6 patients with PSA levels below baseline and 3/6 patients with PSADT increases of 80 to 300 percent, relative to their pre-treatment PSADT.
4/6 patients achieved declines in their serum interleukin-6 (IL-6) level of between 75 and 99 percent from baseline. (Serum IL-6 is a putative biomarker of metastatic prostate cancer.)
Systemic immunological responses were determined by assessment of a panel of chemokines and cytokines at each dose and 1 week after each dose. Clinically responding subjects tended to exhibit dramatic and consistent increases in these serum markers 1 week after each dose, returning to baseline the following week. Antigen-specific immune responses, measured in injection site reaction biopsies taken after three doses, were detected in 4/4 assessable subjects.
The apparent dose-response correlation between clinical and immunological responses still needs to be investigated in six patients who are currently enrolling in a third, high-level dose cohort.