Imprime PGG Added to Chemoimmunotherapy Shows Improved Outcomes in Advanced Lung Cancer Patients
The addition of Imprime PGG, a type of immunotherapy, to chemoimmunotherapy with carboplatin, paclitaxel, and cetuximab (Erbitux) resulted in improved response rates and overall survival rates in patients with late-stage, non–small cell lung cancer (NSCLC), according to the results of a phase II study by Richard D. Huhn, MD, and colleagues. The study results were presented at the AACR-IASLC Joint Conference on the Molecular Origins of Lung Cancer in San Diego.
Imprime PGG, a yeast-derived beta 1,3/1,6 glucan, primes innate immune cells to kill monoclonal antibody (MAb)-targeted cancer cells via a mechanism dependent on complement receptor 3 (CR3). Naturally occurring anti–beta glucan antibodies are required for binding of Imprime PGG to CR3 on immune cells in humans. The researchers developed a quantitative assay to measure these antibodies in serum. Study participants wereconsidered “biomarker positive” or “biomarker negative” depending on their levels conducive to binding.
“Imprime PGG is an immunotherapy that capitalizes on a natural defense mechanism in our bodies through which immune cells called neutrophils and monocytes recognize and kill infectious organisms,” Dr. Huhn, Medical Director and Senior Vice President at Biothera Inc, the manufacturer of Imprime PGG, said in a statement. “When combined with an antitumor monoclonal antibody, Imprime PGG redirects neutrophils and monocytes to recognize and kill antibody-targeted cancer cells.”
According to Dr. Huhn, Imprime PGG works most effectively in people whose natural anti–beta glucan antibody levels exceed a certain threshold. “The more antibodies present to bind Imprime PGG to neutrophils and monocytes, the higher the number of these immune cells that are activated to recognize and kill cancer,” he said in a statement.
Study Methodology
In this phase II study, the researchers recruited 90 patients with stage IIIB or IV NSCLC. Thirty patients were randomly assigned to the control group and received cetuximab, and 60 patients were randomly assigned to cetuximab plus Imprime PGG on days 1, 8, and 15 of each 3-week treatment cycle. All the patients also received carboplatin and paclitaxel. Of the 46 patients who received Imprime PGG and were evaluable for endpoints, 15 were biomarker-positive and 31 were biomarker-negative.
Study Results
Patients in the control group and Imprime PGG group had a median overall survival of 11.2 months and 10.2 months, respectively. However, among patients who received Imprime PGG, the median overall survival for those who were biomarker-positive was 16.5 months vs 9.1 months for those who were biomarker-negative.
Although none of the patients from the control group survived for 3 years after treatment, 7% of the Imprime PGG group did. Among patients who received Imprime PGG, 17% of those who were biomarker-positive survived for 3 years after treatment, while none of the biomarker-negative patients did.
Generally, all adverse events were consistent with toxicities attributable to the cytotoxic drugs or cetuximab and occurred in 86% of the patients in the control group and 78% of the patients in the Imprime PGG group.
“The addition of Imprime PGG to chemotherapy with carboplatin, paclitaxel, and cetuximab resulted in improved outcomes in [biomarker-positive] subjects with respect to increased [response rate] and extended survival compared to control subjects and had a good safety profile,” concluded the researchers.
The study was funded by Biothera Inc. Dr. Huhn is an employee of Biothera Inc.
The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.
