The following article features coverage from the Society of Immunotherapy of Cancer (SITC) 2020 meeting. Click here to read more of Cancer Therapy Advisor‘s conference coverage.

A personalized vaccine of neoantigens was well tolerated by patients with different solid and hematologic malignancies, according to the preliminary results of a phase 1 study presented at the virtual Society for Immunotherapy of Cancer 35th Anniversary Annual Meeting & Preconference Programs (SITC 2020).

Antigen presentation is critical for an effective T-cell response to cancer cells. The aim of this study was to develop and test a personalized genomic vaccine, which was designed to augment neoantigen production.

The open-label phase 1 proof-of-concept study treated 15 patients with PGV-001, a personalized peptide vaccine, plus poly-ICI. The vaccine was individualized for each patient and was given as 2 injections, with each injecting up to 5 peptides, for a total of up to 10 peptides per patient. Peptides, or neoantigens, were selected based on machine learning and bioinformatics of tumor and germline RNA and DNA sequences from each patient.

Patients were those with solid tumors who underwent surgery with curative intent or had who multiple myeloma and were undergoing consolidation for autologous stem cell transplant. Patients had completed standard adjuvant therapy at least 4 weeks before vaccine administration.


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The primary endpoints of the study were safety and tolerability, production and administration feasibility, and immunogenicity. Secondary endpoints included immunophenotyping of T cells, and characterization of the immune response.

Of the 15 patients enrolled, 13 were evaluable for efficacy. Seven patients developed an adverse event (AE), all of which were grade 1 injection-site reactions, and 1 patient also developed a grade 1 fever.

A preliminary analysis of the immune response was reported for 1 patient, and immune monitoring is ongoing for all evaluable patients. A T-cell response was observed for 7 out of 10 peptides within the vaccine, including differential responses in the CD4 and CD8 compartments.

The authors concluded that PGV-001 was successfully synthesized and administered. “The vaccine was well tolerated and T-cell expansion and reactivity to synthetic neoantigens confirms immunogenicity of neoantigens identified,” the authors said.

Read more of Cancer Therapy Advisor‘s coverage of the SITC 2020 meeting by visiting the conference page.

Reference

Marron TU, Kodysh J, Rubinsteyn A, et al. PGV-001: A phase 1 trial of a personalized neoantigen peptide vaccine for the treatment of malignancies in the adjuvant setting. Presented at: Society for Immunotherapy of Cancer 35th Anniversary Annual Meeting & Preconference Programs (SITC 2020); November 11-14, 2020. Abstract 289. J Immunother Cancer. 2020;8(Suppl 3):A656–A959.