The PD-1/PD-L1 axis modulates the natural killer cell versus multiple myeloma effect: a therapeutic target for CT-011, a novel monoclonal anti-PD-1 antibody.

T-cell expression of programmed death receptor-1 (PD-1) down-regulates the immune response against malignancy by interacting with cognate ligands (eg, PD-L1) on tumor cells; however, little is known regarding PD-1 and natural killer (NK) cells. NK cells exert cytotoxicity against multiple myeloma (MM), an effect enhanced through novel therapies. We show that NK cells from MM patients express PD-1 whereas normal NK cells do not and confirm PD-L1 on primary MM cells. Engagement of PD-1 with PD-L1 should down-modulate the NK-cell versus MM effect. We demonstrate that CT-011, a novel anti-PD-1 antibody, enhances human NK-cell function against autologous, primary MM cells, seemingly through effects on NK-cell trafficking, immune complex formation with MM cells, and cytotoxicity specifically toward PD-L1(+) MM tumor cells but not normal cells. We show that lenalidomide down-regulates PD-L1 on primary MM cells and may augment CT-011's enhancement of NK-cell function against MM. We demonstrate a role for the PD-1/PD-L1 signaling axis in the NK-cell immune response against MM and a role for CT-011 in enhancing the NK-cell versus MM effect. A phase 2 clinical trial of CT-011 in combination with lenalidomide for patients with MM should be considered.

Early versus delayed autologous stem cell transplant in patients receiving novel therapies for multiple myeloma.

Autologous stem cell transplant (ASCT) is an effective treatment for multiple myeloma (MM). However, the timing of ASCT in the era of novel agents (lenalidomide, thalidomide, bortezomib) is unknown. We retrospectively reviewed the outcome of patients with MM who received novel agent-based induction treatment and received first ASCT within 12 months of diagnosis (early ASCT, n = 102) or at a later date (late ASCT, n = 65). Median time to ASCT was 7.9 months vs. 17.7 months in early vs. late ASCT. The 3- and 5-year overall survival (OS) from diagnosis was 90 and 63% vs. 82 and 63% in early and late ASCT, respectively (p = 0.45). Forty-one and 36 patients in the early and late ASCT groups have relapsed or progressed, with median time to relapse of 28 and 23 months (p = 0.055). On multivariable analysis, factors predictive of increased risk for progression were International Scoring System (ISS) stage III (p = 0.007), and less than a very good partial response (< VGPR) post-ASCT (p < 0.001). A factor predictive of worst outcome for OS was being on hemodialysis (p = 0.037). No superiority of one agent was seen. In summary, early or late ASCT is a viable option for patients with MM receiving induction treatment with novel targeted therapies.