Biothera reports positive results from Phase 2 clinical trial of Imprime PGG in NSCLC patients

Biothera today reported positive results from its proof of concept Phase 2 clinical trial in 90 patients with advanced non-small cell lung cancer (NSCLC) at the American Association for Cancer Research and the International Association for the Study of Lung Cancer joint conference on the Molecular Origins of Lung Cancer in San Diego.

The purpose of the open label, multicenter, randomized trial was to evaluate the safety and effectiveness of Biothera's immunotherapeutic drug candidate, Imprime PGG^®, with cetuximab (Erbitux^®), carboplatin and paclitaxel compared with the monoclonal antibody and chemotherapy combination alone in previously untreated patients with advanced NSCLC. The primary endpoint of the study was Objective Response Rate and a secondary endpoint was Overall Survival.

"We believe that combination therapies with Imprime PGG may significantly increase survival rates for many cancers, including the most difficult to treat like lung cancer and colorectal cancer, without adding to the toxicity of the backbone therapy," said Dan Conners, president of Biothera's Pharmaceutical Group. "The opportunity to provide an effective immunotherapy with overall survival benefits for squamous cell NSCLC patients, a clinically unmet need, is very exciting."

Study Results
The combination of Imprime PGG with cetuximab and carboplatin/paclitaxel showed a substantial and statistically significant improvement in objective response rate (ORR) of 48%(p=0.048) in the Imprime PGG treated group compared to 23% in the control group. This improvement was even greater in the biomarker-positive subgroup, which had an ORR of 67% (p=0.009). Beneficial effects were observed in both squamous and non-squamous NSCLC patients. Among patients with squamous cell NSCLC, a cancer for which there few treatment options today, the ORR was 100% (N=6) for biomarker-positive Imprime PGG subjects compared with 30% (N=10) for control group subjects (p=0.01).

Biothera researchers discovered a predictive biomarker that identifies patients who are most likely to best respond to Imprime PGG, a patented, complex carbohydrate (a beta glucan) derived from the cell walls of a proprietary strain of yeast. The biomarker is a naturally occurring antibody to beta glucan that is required for binding Imprime PGG to neutrophils and monocytes, the largest population of immune cells in the body. When bound, Imprime PGG engages and directs these innate immune cells to recognize and kill antibody-targeted cancer cells. Using a serum-based assay, Biothera is able to identify biomarker-positive patients.

Although the study was not powered for Overall Survival, the results indicated a strong trend for improvement in the biomarker-positive subgroup as well. The Median Overall Survival for the biomarker-positive Imprime PGG-treated subgroup was 16.5 months compared with the control group of 11.2 months. Positive survival benefits were also observed in squamous cell as well as non-squamous cell NSCLC patients.

Imprime PGG was well tolerated, with adverse events consistent with toxicities attributable to the cytotoxic drugs or cetuximab alone.

"Numerous preclinical studies have demonstrated the effectiveness of the combination therapy of Imprime PGG and monoclonal antibodies in multiple tumor models. The current clinical data confirm the preclinical results and validate Biothera's approach of modulating the innate immune system to fight virtually all types of cancer," said Myra Patchen, Ph.D., chief scientific officer, Biothera's Pharmaceutical Group. "The excitement about the biomarker is that it links directly to the mechanism of action of Imprime PGG and now we have clinical data supporting its use. This discovery will enable future clinical trials to be enriched for subjects most likely to respond to Imprime PGG."