Phase I/II safety, efficacy data for Bellicum's BPX-101 presented at 2011 Genitourinary Cancers Symposium

Bellicum Pharmaceuticals, Inc. today announced the presentation of Phase I/II safety and efficacy data for BPX-101, a novel drug-activated dendritic cell vaccine for metastatic castrate resistant prostate cancer (mCRPC), in three separate posters at the 2011 Genitourinary Cancers Symposium held in Orlando, Florida on February 17 – 19, 2011. Three leading medical specialty societies co-sponsor the symposium, including the American Society of Clinical Oncology (ASCO), the American Society for Radiation Oncology (ASTRO) and the Society of Urologic Oncology (SUO).

• Guru Sonpavde, M.D., Principal Investigator of the Phase I/II trial, presented data that demonstrated objective clinical responses, including RECIST Partial and Complete Responses, in patients treated with BPX-101.
• David M. Spencer, Ph.D., Vice Chairman of Pathology & Immunology at Baylor College of Medicine, showed that BPX-101 can induce a spiking pattern of inflammatory cytokine elevations after each dose.  In patients who experienced measurable disease reductions, more dramatic spikes in these cytokine levels were seen.
• Thomas M. Wheeler, M.D., Chairman of Pathology & Immunology at Baylor College of Medicine, presented data that suggests vaccination with BPX-101 can induce a strong Prostate Specific Membrane Antigen (PSMA)-specific immune response.  In addition, tumor biopsy evidence of severe prostate cancer-specific inflammation and necrosis, associated with a strong PSMA-specific immune response, was observed after multiple doses of BPX-101.

The trial was designed to establish the safety and maximum tolerated dose of BPX-101 in combination with activating agent AP1903, administered every other week for six doses. Exploratory efficacy endpoints included radiological and biochemical assessments of clinical response, and assessments of serum and biopsy samples for systemic and antigen-specific immunological responses.  

Of the twelve subjects enrolled in the trial, all had Gleason Scores > 7, and 9 of 11 had Gleason Scores > 8.  The median Halabi-predicted survival was 13.8 months.  Six had failed prior docetaxel chemotherapy and one subject had failed prior abiraterone therapy.  Three subjects had visceral metastases.  The median pretreatment PSADT was 4.9 months (mean 4.25 months).

Phase I/II data from these twelve high risk subjects treated at low, medium and high doses support the following conclusions regarding the clinical activity of BPX-101 and AP1903:

• The combination of BPX-101 and AP1903 appears safe and well tolerated at doses up to 25 million cells and 0.4 mg/kg respectively, on an EOW x 6 schedule. Drug related adverse events were mild or moderate and primarily limited to fatigue and expected injection site reactions.
• Treatment with BPX-101 and AP1903 elicited difficult to achieve RECIST Partial and Complete Responses in three of twelve (25%) patients, including Complete Responses in patients with visceral metastatic disease.
• Two of twelve (17%) subjects experienced PSA declines approaching 50% within the first 12 weeks of therapy, including one rapidly progressing subject who experienced an 85% decline from 1070 to 169 ng/mL after a single vaccination.  Both subjects experienced clinical, symptomatic improvement in conjunction with these PSA declines. PSA Doubling Times were substantially prolonged in the majority of patients.
• Treatment with BPX-101 and AP1903 elicited immunological responses, including PSMA antigen-specific immune responses, and systemic inflammatory cytokine "spikes" in the majority of subjects evaluated.

"Our data challenges the prevailing notion that cancer vaccines cannot shrink tumors. BPX-101-treated patients have experienced measurable disease responses, including elimination of poor-risk visceral disease," stated Bellicum Founder, President and Chief Medical Officer, Kevin M. Slawin, M.D. "These results attest to the power of our DeCIDe™ technology platform to activate the immune system in an unprecedented way."

Bellicum plans to initiate Phase II trials later this year.