Skip to Content

Combination of Imprime PGG and Erbitux Doubles the Therapeutic Response in Colorectal Cancer Patients in Phase Ib/IIa Trial

Data Released at the European Society for Medical Oncology

BARCELONA, Spain--(BUSINESS WIRE)--Jul 6, 2010 - The combination of Biothera's experimental drug Imprime PGG® and Erbitux® (cetuximab) doubled the historical overall response rate and the time to progression of second- and third-line metastatic colorectal cancer patients treated with Erbitux monotherapy. The data was released last weekend at the 13th World Congress on Gastrointestinal Cancer at the European Society for Medical Oncology (ESMO).

“The results indicate that this combination is a potentially effective alternative to standard of care therapies that utilize chemotherapy,” said Dan Conners, president of Biothera's Pharmaceutical Group. “We believe these results suggest a potential major advancement in the treatment of colorectal cancer. Extending life and eliminating the harmful side effects of chemotherapy would be a significant benefit to cancer patients. Further research is warranted by these results.”

Study Design

The Phase Ib/IIa, sequential, dual-arm, open-label, dose-escalation study is evaluating the safety and efficacy of Imprime PGG plus irinotecan and cetuximab (Arm #1) or Imprime PGG plus cetuximab alone (Arm #2) for second- and third-line colorectal cancer patients. Results from study Arm #2 are the subject of new data released at ESMO. Arm #1 data was released at the American Society of Clinical Oncology (ASCO) annual meeting in 2009.

Arm #2 of the study included 22 patients dosed with 2 mg/kg, 4 mg/kg or 6 mg/kg of Imprime PGG in combination with standard doses of cetuximab. Imprime PGG was safe and well tolerated.

All tumor responses and duration of responses were based on Response Evaluation Criteria in Solid Tumors (RECIST), Version 1.0. The benchmark data for cetuximab monotherapy in second- and third-line colorectal cancer patients is based on the BOND Study (Cunningham et al., NEJM, 2004), which was conducted in a similar patient population.

Biothera Colorectal Cancer Phase Ib/IIa Arm #2 Study Results


Erbitux Alone*


    Erbitux +
Imprime PGG


Response Rate     11%     24%
Stable Disease Rate     22%     38%
Disease Control Rate     33%     62%
Progression-Free Survival     6 weeks     12 weeks
Number of patients in trial     111     21
* Erbitux (cetuximab) alone data from the BOND study, Cunningham et al., NEJM 2004.

The study also retrospectively looked at subpopulations of the colorectal cancer patients based on those whose tumors expressed wild type versus mutated KRAS genes. In the wild type KRAS patient population responses were even more pronounced as shown below.

Biothera Colorectal Cancer Phase Ib/IIa Arm #2 Study
Results for KRAS Wild Type Patients

      Erbitux Alone*


    Erbitux +
Imprime PGG
Response Rate     17%     46%
Stable Disease Rate     49%     36%
Disease Control Rate     66%     82%
Progression-Free Survival     11 weeks     24 weeks
Number of patients in trial     262     11
* Erbitux (cetuximab) alone KRAS wild type data represent the mean of response data reported from 4 published studies (Khambata JCO 2007, DeRook Ann Oncol 2008, Lurje Clin Cancer Res 2008, Karapetis NEJM 2008; Total subjects from all Studies = 262.)

“Data from both arms of this trial strongly support our extensive preclinical evidence that Imprime PGG engages the innate immune system in a way that it enables it to identify and kill Erbitux-targeted cancer cells,” said Conners. “Because Imprime PGG works in concert with potentially any complement-activating antibody, this technology could be used to treat almost all types of cancers.”

About Imprime PGG®

Imprime PGG® is a novel immunotherapy that works synergistically with anti-tumor monoclonal antibodies to activate a large population of the body's immune cells (neutrophils) to kill cancer cells. Imprime PGG is currently in multiple Phase II clinical trials for lung and colorectal cancer. While some drugs trigger a broad innate immune response, Imprime PGG® activates immune cells without inducing systemic pro-inflammatory cytokines that are attributed to adverse reactions. As a platform therapeutic in oncology, Imprime PGG® has the potential to improve patient response rates for existing monoclonal antibody therapies in approved indications, create new indications for these drugs and enhance the efficacy of development-stage monoclonal antibody drugs.

About Biothera, the Immune Health Company

Biothera is a biotechnology company dedicated to improving immune health. The company is developing pharmaceuticals that engage the innate immune system to fight cancer. (


Contact: Biothera, the Immune Health Company
David Walsh, 651-256-4606 (direct)
VP Communications


Posted: July 2010