Biothera’s Investigational Cancer Immunotherapy Alleviates Immune Suppression By Regulatory T Cells, Enabling CD4 And CD8 T Cell Proliferation, Study Finds

New Data Presented at the American Association for Cancer Research Annual Meeting

PHILADELPHIA--(BUSINESS WIRE)--Biothera’s investigational cancer immunotherapy Imprime PGG enhances the function and proliferation of T cells that play a critical role in the fight against cancer, according to new data presented today at the American Association for Cancer Research (AACR) annual meeting.

“We are particularly excited now to pursue these findings further through in vivo tumor studies.”

“Cancer can create an immunosuppressive environment that enables it to avoid detection and evade destruction by the immune system,” said Jeremy Graff, Ph.D., Senior Vice President, Biothera Pharmaceutical Research. “Imprime PGG activates innate immune effector cells to kill antibody-decorated, complement-opsonized cancer cells and to initiate cross talk that awakens the adaptive arm of the immune system for a coordinated anti-tumor response.”

Biothera researchers demonstrated that plasma from Imprime PGG-treated whole blood was able to reduce the ability of regulatory T cells to suppress CD4+ T cells. Imprime PGG also enhanced the proliferation of both CD4+ and CD8+ T cells in response to in vitro stimulation. This T cell expansion was accompanied by upregulation of the transcription factor T-bet and increased production of the potent anti-tumor cytokine interferon gamma (IFN-?), suggesting Imprime PGG may drive polarization of T cells to a Th1, anti-tumor phenotype.

“These effects were observed when Imprime PGG was added to whole blood and not to isolated plasma, suggesting that they are indirect and may involve cross talk from the innate immune system,” said Dr. Graff.

The combined effect of Imprime PGG treatment may “flip” the immune microenvironment from an immune-suppressive, pro-tumor state to an anti-tumor, attack mode. Other new data presented separately at this year’s AACR annual meeting also indicate that Imprime PGG treatment enhances maturation of dendritic cells and re-orients the functional activity of macrophages, allowing both innate immune effector cell types to effectively instruct T cell expansion and to enhance IFN-? production.

“Together, these studies provide compelling evidence that Imprime PGG treatment may trigger a cascade of effects that result in a highly orchestrated anti-cancer response involving both arms of the immune system,” said Dr. Graff. “We are particularly excited now to pursue these findings further through in vivo tumor studies.”

Biothera’s poster presentation (Abstract #5034) on T cells will take place between 8:00 am and 12:00 pm today in section 11, poster board number 26 at the Pennsylvania Convention Center. The presentation is entitled, “Imprime PGG decreases regulatory T cell suppression and enhances T cell proliferation and differentiation revealing additional mechanisms for its anti-tumor activity.”

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.

More information is available at http://www.biothera.com/pharma or follow us on Twitter.