ImMucin is a 21-mer long peptide therapeutic vaccine encoding the entire signal peptide (SP) domain of the MUC1 tumor-associated antigen, which is over expressed by most hematological tumors including multiple myeloma (MM). Preclinical studies of ImMucin and its internal epitopes in multiple myeloma suggested superior immunological and anti-tumor properties compared to other MUC1 TRA‐derived epitopes. ImMucin demonstrated encouraging short and long-term safety profile. Vaccination induced a remarkable anti-MM immune response. However, immunity was transient suggesting a need for boosting. Interestingly, durable disease stabilization was achieved in the third of the patients, continuing despite the loss of immune response in peripheral blood. Moreover, the encouraging responses to subsequent therapies employed at clinical progression, suggest this novel approach to be potentially valuable in the setting of maintenance and/or early biochemical progression.