To improve the immune contribution of autologous stem cell transplant (autoSCT) to long-term survival in multiple myeloma patients, Cohen and Lendvai et al. added autologous lymphocyte infusion of MAGE-A3-primed T cells shortly after autoSCT, followed by continued vaccination with full-length MAGE-A3 protein. Humoral and CD4+ T cell responses were detected in all patients, with only a small subset showing CD8+ responses. CD8+ T cells recognized processed antigen. Interestingly, in 4 of 8 patients biopsied following relapse, MAGE-A expression was lost compared to baseline, suggesting immune escape.
Autologous stem cell transplant (autoSCT), the standard consolidation therapy for multiple myeloma, improves disease-free survival but is not curative. This could be an ideal setting for immunologic therapy. However, the immune milieu is impaired after autoSCT. We hypothesized that autologous lymphocyte infusion would restore immune competence, allowing immunotherapies such as cancer vaccines to elicit tumor antigen-specific immunity in the setting of autoSCT. In this pilot study (NCT01380145), we investigated safety, immunologic, and clinical outcomes of autologous lymphocyte infusion combined with peri-autoSCT immunotherapy with recombinant MAGE-A3 (a multiple myeloma-associated antigen) and adjuvant. Thirteen multiple myeloma patients undergoing autoSCT were enrolled. Autologous lymphocyte infusion and MAGE vaccination were well tolerated. Combination immunotherapy resulted in high-titer humoral immunity and robust, antigen-specific CD4+ T-cell responses in all subjects, and the responses persisted at least one year post-autoSCT. CD4+ T cells were polyfunctional and Th1-biased. CD8+ T-cell responses were elicited in 3/13 subjects. These cells recognized naturally processed MAGE-A3 antigen. Median progression-free survival was 27 months, and median overall survival was not reached, suggesting no differences from standard-of-care. In 4/8 subjects tested, MAGE-A protein expression was not detected by immunohistochemistry in multiple myeloma cells at relapse, suggesting therapy-induced immunologic selection against antigen-expressing clones. These results demonstrated that autologous lymphocyte infusion augmentation of autoSCT confers a favorable milieu for immunotherapies such as tumor vaccines. This strategy does not require ex vivo manipulation of autologous lymphocyte products and is an applicable platform for further investigation into combination immunotherapies to treat multiple myeloma.