Background: Over the past two decades, most cancer vaccines have failed to be developed clinically. The lack of efficient priming with specific tumor antigens and/or weak adjuvants may explain this poor success rate. MVX-ONCO-1, a personalized cell-based vaccine, combines inactivated autologous tumor cells and encapsulated allogeneic human cells genetically engineered to produce granulocyte-macrophage colony stimulating factor (GM-CSF). This unique technology allows sustained local delivery of strong adjuvant at the vaccination site. The combination of inactivated autologous tumor cells and potent local adjuvant delivery addresses these two unmet critical steps and may recapitulate in patients the successful combination observed in experimental models.

Methods: The SAKK 11/16, a Phase IIa trial with Overall Survival (OS) as the primary endpoint was the first efficacy study evaluating MVX-ONCO-1. Patients with Recurrent/Metastatic Head and Neck Squamous Cell Carcinoma (R/M HNSCC) progressing after at least one line of systemic therapy were enrolled with 50% of patients alive at 26 weeks as the primary objective.

Results: In this hard-to-treat population, SAKK 11/16 met the primary endpoint, with 68.8% of patients alive at 6 months. The median OS was 11.4 months, with 32% of the patients alive after 18 months. Complete and partial responses were observed on MVX-ONCO-1 monotherapy. Moreover, all patients who developed a positive DTH reaction to their tumor cells upon vaccination survived at 12 months. Additionally, patients living for more than 12 months had higher circulating antibody titers against tumor-associated antigens. Explorative analysis looking at median OS from the start of anti-PD-1 therapy was 21.7 months. In addition, no new safety signals with no systemic adverse events (AE) related to the treatment and no manufacturing issues were observed in this multicenter trial.

Conclusions: These findings suggest that MVX-ONCO-1 can induce a coordinated immune response with clinical benefits as a standalone treatment, leading to prolonged survival. This effect may be enhanced by previous exposure to immune checkpoint inhibitors. Trial registration (ClinicalTrials.gov): NCT02999646.