An Allogeneic Multiple Myeloma GM-CSF-Secreting Vaccine with Lenalidomide Induces Long-term Immunity and Durable Clinical Responses in Patients in Near Complete Remission

Purpose: This proof-of-principle clinical trial evaluated whether an allogeneic multiple myeloma GM-CSF-secreting vaccine (MMGVAX) in combination with lenalidomide could deepen the clinical response in patients with multiple myeloma in sustained near complete remission (nCR). Patients and Methods: Fifteen patients on lenalidomide were treated with MM-GVAX and pneumococcal conjugate vaccine (PCV; Prevnar) at 1, 2, 3, and 6 months. Results: Eight patients (53.3%) achieved a true CR. With a median follow-up of 5 years, the median progression-free survival had not been reached, and the median overall survival was 7.8 years from enrollment. MM-GVAX induced clonal T-cell expansion and measurable cytokine responses that persisted up to 7 years in all patients. At baseline, a higher minimal residual disease was predictive of early relapse. After vaccination, a lack of both CD27_DNAM1_CD8 T cells and antigen-presenting cells was associated with disease progression. Conclusions: MM-GVAX, along with lenalidomide, effectively primed durable immunity and resulted in long-term disease control, as suggested by the reappearance of a detectable, fluctuating Mspike without meeting the criteria for clinical relapse. For patients in a nCR, MM-GVAX administration was safe and resulted in prolonged clinical responses.