Biothera’s Investigational Cancer Immunotherapy Drug Imprime PGG Elicits Dramatic Expansion Of Cytotoxic T Cells

Late-Breaking Data Presented at the American Association for Cancer Research (AACR) Annual Meeting

PHILADELPHIA--(BUSINESS WIRE)--Biothera researchers are presenting several studies at this year’s AACR meeting showing that treatment with its investigational immunotherapy Imprime PGG consistently triggers expansion of cytotoxic T cells (CD8+ T cells)—cells critically responsible for eradicating virally infected cells and for selectively killing cancer cells. A late-breaking research poster being presented today provides the first evidence that Imprime PGG may have utility as a cancer vaccine platform.

“Together, these data show that an Imprime PGG-protein conjugate can effectively elicit the expansion and functional activation of cytotoxic T cells and suggest that Imprime PGG may have utility as a potential cancer vaccine platform”

“In this proof of concept study, Imprime PGG, when directly conjugated to a model antigen, enabled the professional antigen presenting cells–specifically the cross-presenting dendritic cells–to drive a profound CD8+ T cell response,” said Jeremy Graff, Ph.D., Senior Vice President, Biothera Pharmaceutical Research. “Not only did the population of these killer T cells expand more than 100-fold, but these cells also increased expression of the cytokines essential to their cytotoxic activity.”

Other Biothera research presented separately at this year’s AACR meeting demonstrated that Imprime PGG enables the maturation of the innate immune system’s dendritic cells, which are primarily responsible for presenting antigens to the adaptive immune system. Biothera researchers reasoned that Imprime PGG might consequently enhance the response of the adaptive immune system–specifically cytotoxic CD8+ T cells–to a model antigen, chicken ovalbumin (OVA). Remarkably, the direct conjugation of Imprime PGG to OVA elicited profound expansion in the number of cytotoxic T cells when compared to that induced by OVA alone. Moreover, the Imprime PGG-OVA conjugate triggered expression of the key transcription factor Tbet and the production of interferon gamma (IFN-?), tumor necrosis factor alpha (TNF-a) and interleukin 2, cytokines critical for the cytotoxic function of these T cells.

“Together, these data show that an Imprime PGG-protein conjugate can effectively elicit the expansion and functional activation of cytotoxic T cells and suggest that Imprime PGG may have utility as a potential cancer vaccine platform,” said Dr. Graff.

Biothera’s research (Abstract #LB-236) is one of three late-breaking poster presentations the company will present from 1:00 pm – 5:00 pm today in Section 39 at the Pennsylvania Convention Center. The presentation is entitled, “Imprime PGG conjugated directly to protein enables cross-presentation of antigen that generates multifunctional cytotoxic T cells.”

About Biothera

Biothera is a privately held biotechnology company developing Imprime PGG, a late clinical stage immunotherapeutic drug candidate that modulates key immune cells to recognize and kill cancer. Proof of concept has been established from randomized and single-arm Phase 2 studies in non-small cell lung cancer (NSCLC), colorectal cancer, and chronic lymphocytic leukemia. In the NSCLC study, which evaluated the addition of Imprime PGG to bevacizumab and carboplatin/paclitaxel versus bevacizumab and chemotherapy alone, objective response rate was 60.4% versus 43.5%, duration of response was 10.3 months versus 5.6 months and median overall survival was 16.1 months versus 11.6 months. Studies are ongoing in metastatic colorectal cancer, pancreatic cancer and non-Hodgkin lymphoma. In addition, new research shows that Imprime PGG elicits a coordinated immune response that involves both innate and adaptive immunity.

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