Immunomodulation in Pomalidomide, Dexamethasone, and Daratumumab-Treated Patients with Relapsed/Refractory Multiple Myeloma.

PURPOSE

Addition of daratumumab to pomalidomide and low-dose dexamethasone (LoDEX) is a safe and effective combination for relapsed/refractory multiple myeloma treatment. We sought to better understand immune combinational benefit of pomalidomide and daratumumab with LoDEX.

PATIENTS AND METHODS

Immunophenotypic changes were analyzed in peripheral blood from longitudinal sampling of patients treated with this triplet regimen from cohort B of the CC4047-MM-014 phase II trial (NCT01946477).

RESULTS

Consistent with the daratumumab mechanism, treatment led to decreased natural killer (NK) and B cells. In contrast, pronounced increases occurred in activated and proliferating NK and T cells, appreciably in CD8 T cells, along with reduction in naïve and expansion of effector memory compartments. Timing of T-cell changes correlated with pomalidomide dosing schedule. Enhanced activation/differentiation did not result in increased exhausted T-cell phenotypes or increases in regulatory T cells. Similar immune enhancements were also observed in patients previously refractory to lenalidomide.

CONCLUSIONS

These data support a potential mechanism for enhanced immune-mediated cytotoxicity in which daratumumab-mediated NK-cell diminution is partially offset by pomalidomide effects on the remaining NK-cell pool. Furthermore, daratumumab antimyeloma activity and elimination of CD38 T cells (regulatory/activated) provide a rationale for therapeutic combination with direct tumoricidal activity and immunomodulation of pomalidomide-directed T-cell enhancements. These data highlight enhancements in immune subpopulations for the combination of daratumumab with pomalidomide and potentially with next-generation cereblon-targeting agents.