A Systematic Review of Evidence Supporting the Use of Autologous Cell Vaccines in the Treatment of Hematological Malignancies

By presenting a patient's own tumor antigens to their immune system, autologous cancer cell vaccines can drive a robust polyclonal adaptive response. In this systematic review and meta-analysis, we investigated the safety and efficacy of these vaccines administered to patients with hematologic malignancies. Our primary outcomes of interest were safety and clinical response, with secondary outcomes including overall, disease-free and progression-free survival, relapse rate, correlative immune assays and health-quality related metrics. We identified 14 studies with 332 patients enrolled, of which 200 were ultimately treated with at least one dose of the vaccine. While we identified both patient-related and technical issues that might limit the feasibility of these trials, very few serious adverse events (AEs) were reported overall, with only 31.5% of patients suffering any AEs. Grade II or lower AE was observed in 10 (71.4%) of the 14 studies. Of the 3 (21.4%) reporting grade IV AEs, two observed the AE in one patient only, and one reported a 20% incidence of grade II-IV AEs. Of 58 evaluable patients, the complete response rate was 21% [95% CI, 10%-38%)] and overall response rate was 36% [95% CI, 24%-49%]. Analysis of individual patient level data (n=50) revealed a 5-year overall survival of 68.7% (SE 7.1%) and disease-free survival of 67.4% (SE 8.1%). Despite the clear safety and a signal towards efficacy, our review has identified several factors limiting administration of these vaccines, which should be considered when developing future clinical trials. PROSPERO registration number CRD42019140187 Diallo:Virica Biotech: Other: Owner and Executive. Auer:Imugene: Other: Scientific Advisory Board. Kekre:Gilead: Consultancy, Honoraria; Novartis: Consultancy, Honoraria; Celgene: Consultancy, Honoraria.