Therapy Shown to Boost Immune System Against Cancer

Carcinoid lung tumor (Yale Rose, Flickr)

18 April 2016. An experimental treatment was shown in lab mice to enhance immune system cells that can help immunotherapy drugs to reduce solid tumor growth. Researchers from Memorial Sloan Kettering Cancer Center in New York and Infinity Pharmaceuticals in Cambridge, Massachusetts presented their findings yesterday (17 April) at the annual meeting of American Association for Cancer Research in New Orleans.

Infinity Pharmaceuticals is developing cancer treatments that target the phosphoinositide-3-kinase, or PI3K, signaling pathways associated with a wide range of cancers in humans. The therapy in this case, code-named IPI-549, is a small-molecule or low molecular weight treatment designed to limit PI3K-gamma signals that block immune system cells from acting on tumor growth. In particular, PI3K-gamma signals promote the support system that protect tumors from immune cells.

The team from Sloan Kettering and Infinity tested IPI-549 given as oral treatments to mice induced with human lung cancer. The results show mice given IPI-549 had lower levels of myeloid cells that support the ability of tumors to suppress immune system cells. Mice given IPI-549 also reported higher levels of CD8+ or cytotoxic T-cells in the immune system that attack tumors, which with the reductions in myeloid cells, indicate the treatments can disrupt the protective environment built up by tumors.

In separate findings on a poster at the AACR meeting, Infinity reported that IPI-549 treatments given with immunotherapy treatments to lab mice induced with solid tumor cancers had less tumor growth than mice given the immunotherapies alone. The company tested IPI-549 with a type of immunotherapy known as checkpoint inhibitors that limit the actions of tumor cells to block the immune system.

The results show mice receiving IPI-549 with immunotherapy treatments had more complete responses, less tumor growth, and greater survival than those getting immunotherapy alone. Mice with IPI-549 and immunotherapy having complete responses also reported little or no tumor growth when tumors were regrafted, suggesting a continuing effect of the treatments.

Infinity is testing the safety and effects on the body of IPI-549 in an early-stage clinical trial with individuals having advanced cases of non-small cell lung cancer and melanoma. The company is recruiting 150 participants, who will be given IPI-549 alone, or with pembrolizumab, a checkpoint inhibitor approved by FDA to treat those cancer types.

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