Company News: ISA Pharmaceuticals – New Study Explains Synergy between Cancer Vaccine ISA101 and Chemotherapy
– Tumor necrosis factor alpha (TNFα) produced by T cells following vaccination sensitizes tumor cells for eradication by certain chemotherapeutics
– Data published in Clinical Cancer Research support ongoing clinical development of ISA101
ISA Pharmaceuticals B.V., a clinical-stage immunotherapy company focusing on rationally designed immunotherapeutics against cancer and persistent viral infections, has announced new findings on the synergy between its synthetic long peptide (SLP®) cancer vaccine and chemotherapeutics. Data published in Clinical Cancer Research* demonstrate that combined chemo-immunotherapy leads to superior T cell-mediated tumor eradication in the absence of T cell immunosuppression.
In a preclinical model of cancer induced by human papillomavirus type 16 (HPV16), ISA’s lead SLP® candidate ISA101 was combined with seven clinically relevant chemotherapeutics to treat established tumors. The researchers tested either ISA101 or chemotherapeutics alone as well as combinations of both. Topotecan, gemcitabine, carboplatin and cisplatin showed synergies with ISA101. The most effective combination was cisplatin plus ISA101, resulting in tumor regression and the durable survival of 75% of the mice, and a lasting immune response. Most importantly, synergy occurred to the same extent at only 40% of the maximum tolerated dose (MTD) of cisplatin, allowing for a reduction of chemotherapy-associated side effects as seen at MTD. There was no synergy between ISA101 and oxaliplatin, doxorubicin or paclitaxel.
While synergy was not related to overt changes in systemic T cell immunity or increased sensitivity of cisplatin-treated TC-1 tumor cells towards CTL-mediated killing, there was a strongly enhanced leukocyte infiltration of the tumor. Vaccine-specific polyfunctional CD8 T cells were a major component of this infiltration. The cisplatin allowed these cells to migrate earlier into the tumor beds, enabling them to eliminate tumor cells at an earlier stage of disease. Once inside the tumor, the T cells further enhanced tumor cell death by producing pro-inflammatory cytokines such as IFNγ and TNFα. In particular, TNFα produced by intratumoral T cells sensitized the tumor cells for cisplatin, allowing for synergistic cell death.
Another study presented at AACR in 2014, showed that cis-/carboplatin/paclitaxel depletes myeloid derived suppressor cells in patients, and thereby strongly increases an ISA101-mediated immune response.
This finding supports the ongoing clinical development program in which ISA101 is tested in a Phase I/II study (CervISA) in combination with cisplatin/carboplatin and paclitaxel in women with advanced or recurrent cervical cancer.
* van der Sluis TC et al.: Vaccine-induced Tumor Necrosis Factor producing T-cells synergize with cisplatin to promote tumor cell death. Clin Cancer Res. 2014 Dec. 12 pii: clincanres.2142.2014; Epub 2014 Dec. 12,; doi: 10.1158/1078-0432.CCR-14-2142