TPIV200 is a T cell vaccine that consists of five naturally processed peptide antigens derived from the highly prevalent tumor cell surface molecule, Folate Receptor Alpha (FRα). FRα is overexpressed by ~90% of ovarian cancer cells and 80% of triple-negative breast cancer cells, making it an ideal target for comprehensive immunotherapy. Higher levels of FRα expression are also associated with cancer recurrence.
A recent study entitled,“Folate Receptor Alpha Peptide Vaccine Generates Immunity in Breast and Ovarian Cancer Patients” that was published by Clinical Cancer Research in March 2018 highlights the safety and immune responses of TPIV200 vaccination in combination with cyclophosphamide, as well as its ability to generate anti-tumor immune responses in ovarian and breast cancer patients. Patients were immunized over a six-month period and monitored for progression and immune responses over twelve months.
Marker has published a white paper that further details these preliminary data and their potential implications for the company’s ongoing Phase 2 clinical trial of TPIV200 in women with platinum-sensitive ovarian cancer.
In summary, in a Phase I safety trial of the peptide-based therapeutic vaccine candidate TPIV200, ovarian cancer patients (n=10) in first remission showed longer median progression-free survival than what was reported for the standard of care chemotherapy. While the results are not statistically significant due to the small patient population, and the lack of a randomized comparison, they do provide an encouraging basis for further studies. A robust statistical approach is being used in an ongoing Phase II clinical trial of the use of TPIV200 as a maintenance therapy in ovarian cancer patients who are in their first remission after platinum chemotherapy.
A study sponsored by the Mayo Clinic is currently recruiting patients with Triple Negative Breast Cancer in a 280-patient study that is fully funded by the U.S. Department of Defense.
HER2/neu is an antigen that is overexpressed by ~30% of breast cancer cells and is a well characterized molecular target for anti-cancer treatments, with approved drugs like Herceptin (an antibody-based HER2/neu inhibitor) generating annual sales in excess of $6 billion.
Marker’s novel T cell vaccine targeting HER2/neu, TPIV110, consists of five HER2/neu antigens. Like to TPIV200, the antigens that comprise TPIV110 were selected for binding to both MHC class I and class II. Because this vaccine utilizes multiple class II-restricted peptides, it can target a significant portion of the population unlike conventional class I-restricted single peptide vaccines, which generally can only target patients who have a particular HLA restriction.
In a completed Phase I study of TPIV100 (a predecessor to the current candidate TPIV110 that contained only four class II-restricted HER2/neu antigens, the vaccine was safe and well-tolerated by HER2/neu+ breast cancer patients. In this study, 95% of patients showed robust T cell responses to at least two antigens and 75% of patients responded to all four antigens. An additional MHC class I-restricted antigen was added to create the current TPIV110 formulation.