New Study Explains Synergy between Cancer Vaccine ISA101 and Chemotherapy

January 09, 2015

• 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

Leiden, The Netherlands, January 08, 2015 – 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.

“It is fascinating to witness how ISA101 immunotherapy and chemotherapy are helping each other to increase their efficacy,“ said Cornelis Melief, CSO of ISA Pharmaceuticals. “By depleting inhibitory cells, chemotherapy increases the immune response to ISA101, while TNFα produced by intratumoral immune cells after ISA101 treatment sensitizes tumor cells for being eradicated by chemotherapeutics.”

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

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About ISA Pharmaceuticals
ISA Pharmaceuticals B.V. is an immunotherapy company developing rationally designed, fully synthetic immunotherapeutics against cancer and persistent viral infections. The company has built a proprietary immunotherapy platform based on the Synthetic Long Peptide (SLP®) concept and AMPLIVANT® technology, which enable the generation of safe and effective drugs with a known mechanism of action. Synthetic long peptides are broadly applicable to multiple targets and ideally suited for monotherapy, as essential components in combination with conventional cancer treatments, and as novel immunomodulators. SLP® immunotherapies are capable of fully harnessing and directing the body‘s own defenses towards fighting the disease.

ISA101, an SLP® immunotherapy targeting human papillomavirus (HPV)-induced diseases, is currently in clinical development in cervical cancer and anal intraepithelial neoplasia (AIN). Clinical proof-of-concept has been established with ISA101 in vulvar intraepithelial neoplasia (VIN), a pre-cancerous disease caused by HPV.

The company was founded in 2004 by Aglaia Oncology Fund and is based in Leiden, The Netherlands. For more information, please visit www.isa-pharma.com

SLP® and AMPLIVANT® are registered trademarks in Europe.