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

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.

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