Dr. Hubbard on the Use of the PolyPEPI1018 Vaccine Plus Chemotherapy in Metastatic CRC

Joleen M. Hubbard, MD, associate professor, oncology, consultant, practice chair, vice chair, Division of Medical Oncology, Department of Oncology, Mayo Clinic, discusses key survival data from the phase 1b study (NCT05130060) of the PolyPEPI1018 vaccine and the impact of these findings on continued investigations of this vaccine in metastatic colorectal cancer (CRC).

The open-label study investigated the safety and toxicity of the multi-peptide cancer vaccine PolyPEPI1018 plus trifluridine/tipiracil (TAS-102; Lonsurf) in patients with late-stage, advanced microsatellite-stable metastatic CRC, Hubbard begins. PolyPEPI1018 enhances the immunological response to several tumor antigens, while TAS-102 may block the formation of more cancerous growths. Accordingly, this novel combination may increase tumor cell death.

Findings from this trial demonstrated that PolyPEPI1018 plus TAS-102 elicited a median progression-free survival (PFS) of 4 months, Hubbard states. Subgroup data revealed that median PFS was 7.6 months in patients who did not have liver metastases and received the novel regimen, she continues. PolyPEPI1018 plus TAS-102 was also well tolerated and showed an adverse effect profile consistent with that of TAS-102 alone.

Although this trial does show some hypothesis-generating data, the overall study population consisted of 15 patients, Hubbard notes. Further exploration in a larger, phase 2 study is needed to validate these results. Still, data suggest that PolyPEPI1018 plus TAS-102 did increase immunological responses at both a peripheral and tumor level.

Next steps for this research include the investigation of PolyPEPI1018 plus immune checkpoint inhibitor regimens, Hubbard says. A phase 2 follow-up study (NCT05243862) will evaluate the safety, immunogenicity and initial activity of PolyPEPI1018 added to atezolizumab (Tecentriq) in this patient population. Investigators hope to provide another treatment alternative for patients who otherwise would not respond to the immunotherapy alone, Hubbard concludes.