A Decade of Anti-Myeloma Vaccine Development through Early Phase Trials: A Systematic Review

Abstract Introduction: Rationale for anticancer vaccine therapy is based on humoral and/or cellular response against unique tumor antigens (Ag). Peptide vaccines specific for Ag are under investigation for patients with multiple myeloma (MM). Among cell-based vaccines, monocyte derived dendritic cell (MDDC) fused with myeloma cells serve as Ag presenting cells to develop an immune response against a variety of targets. The purpose of this study is to report clinical response and tolerability of anti-myeloma vaccines. Methods: We included phase I and I/II trials developed between January 2008 to December 2017, where vaccines or viruses were used against MM, irrespective of the geo-location, age, and sex. We performed a comprehensive literature search (last update 3-30-2018) using the following databases: PubMed, Embase, AdisInsight, and Clinicaltrials.gov. Results: The initial search identified 2537 early phase studies. After screening by 2 reviewers and categorization by mechanism of action, 25 clinical trials (CT) that involved vaccines and/or viruses were included. We added 1 CT after the manual search. Therapy was given to 3 distinct classes of patients: patients without prior treatment (high risk smoldering MM or stage I MM, 4 CT), as an adjunct therapy for patients undergoing FDA approved treatments [high dose chemotherapy (HDT), allogeneic (allo-SCT) or autologous stem cell transplant (ASCT), 9 CT], and patients with residual or relapsed/refractory (RR) disease after FDA approved therapies (11 CT). Of the included 25 CT, 14 have published results available for analysis. For patients without prior treatments, PVX-410, a multi-peptide vaccine, resulted in at least minimal response (MR) in 50% of patients when combined with lenalidomiden and achieved stable disease (SD) for 60% of patients when used alone at 12 months follow up. Treatment with Idiotype-pulsed mature MMDC targeting idiotype proteins in MM showed MR in 30% of patients and SD in 43% of patients at 12 months. For patients receiving vaccines as an adjuvant treatment, recMAGE-A3 resulted in complete response (CR) and very good partial response (VGPR) in 46% and 54% respectively, at 3 months post ASCT follow up. By 12 months post ASCT, these responses were 38% CR and 23% VGPR. Treatment with MDDC (MAGE3 + Survivin + BCMA) resulted in SD in 42% of patients at a median of 25 months post vaccination and 55 months post ASCT. ScFv-FrC, a DNA fusion vaccine, resulted in CR in 50% and MR/SD in 21% at 52 weeks post vaccination. Ongoing CR/PR was maintained for 3+ years in 57 % patients, 4+ years in 36%, and 5+ years in 14% of patients following ASCT; OS was 64% after a median follow up of 85.6 months . Patients treated with MDDCs/tumor cells fusion vaccine had 69% SD after vaccination and 20% SD at a median of 26 months. When vaccines were given as a salvage therapy in RR MM, ImMucin vaccine showed a CR in 30% of patients during treatment, 20% maintained CR, and 13% had SD at a median of 24 months. Galinpepimut-S vaccine showed CR or very good partial response (VGPR) in 37% of patients at a median of 12 months, and 26% CR and VGPR at 18 months, with a progression free survival rate of 23.6 months. Patients receiving mHag loaded host MDDC vaccination also showed 8% CR for > 6 years (n=1) and 8% PR for 19 weeks (n=1); 33% had SD. Reolysin (wild-type reovirus), a virus-based vaccine, was used in 3 trials for RR MM patients. When alone, 42% of patients had SD and 58% had PD. When combined with dexamethasone and bortezomib 37% of patients had SD lasting for 3 cycles. Whereas, when combined with dexamethasone and carfilzomib, all patients had decrease in monoclonal proteins, with VGPR reported in 28%, PR in 43%, MR in 8%, and SD in 8% patients after 8 cycles. Most vaccines were well tolerated by patients, only grade (G) 1 and G2 side effects (SE), which were mostly flu-like symptoms and local skin reactions. G3 SE included pneumonia with mHag DC and Bcl2 peptide vaccine, GVHD with hTERT tumor vaccine, DVT and rash seen with scFv-FrC DNA vaccines. G4 SE were rare, but seen with reolysin, requiring 2 patients to be removed from study, and with DC/tumor cell fusion vaccine (1 pulmonary embolism). Conclusion Anti-myeloma vaccination therapy appears to be well tolerated, which makes it a promising adjuvant therapeutic agent against MM. Current data reveals positive immunologic activity in most patients and there is possibility of promising clinical responses with further drug development. Disclosures No relevant conflicts of interest to declare.