Management of Relapsed and Refractory Multiple Myeloma

Case Studies Continued

Patient A was noted to have biochemical progression initially, with relapse detectable only in serum free light chains. Treatment commenced at the time of worsening anemia. Notably, his disease originally secreted IgG-kappa and at relapse secreted kappa free light chain only; that is, he developed “light chain escape,” which signifies a high-risk disease and likely heralds clonal evolution [64]. He had excellent caregiver support and lived within 20 minutes of a treatment center. His performance status remained good at the time of relapse and he had normal organ function. He was treated with carfilzomib + pomalidomide + dexamethasone for 4 cycles, achieving a very good partial response. He then received a second ASCT with melphalan conditioning and again achieved stringent complete response. Indefinite maintenance therapy commenced with pomalidomide, and at 16 months post-ASCT he was doing well and still in remission.

Patient B was symptomatic at the time of disease progression. As her primary complaint was that of a painful humeral lytic lesion, she first underwent a course of palliative radiation, which alleviated her pain. She did not wish to restart systemic treatment and instead elected to watch her MM closely with her oncologist on a monthly basis. By 3 months, her M-spike had reached 0.6 g/dL and her serum creatinine had increased slightly, resulting in a creatinine clearance of 34 mL/min. She lived approximately 90 minutes from the closest treatment facility and found it difficult to come for visits more than once monthly. Her Eastern College Oncology Group (ECOG) performance status was 2. With her advanced age and frailty, she was not considered to be a good candidate for ASCT. She requested to go back on lenalidomide and decided with her oncologist to try ixazomib + lenalidomide + dexamethasone, with which she achieved a very good partial response. She had difficulty with myelosuppression with lenalidomide, which was dropped after 4 cycles, and she is planned for ixazomib maintenance until disease progression or drug intolerance. She receives monthly zoledronic acid to reduce the risk of fractures.

Patient C has high-risk disease as indicated by R-ISS III stage disease at diagnosis and progression only 8 months after ASCT and while on bortezomib maintenance therapy. Although he currently only has evidence of biochemical relapse, prompt initiation of treatment was warranted to prevent further renal compromise such as during his initial presentation [65]. Further, PET-CT showed the presence of extramedullary soft tissue disease, another high-risk feature. He was a robust patient with good social support and received carfilzomib + pomalidomide + dexamethasone re-induction. He was not considered for a second ASCT given his short duration of response. With his high-risk features of early relapse after ASCT, R-ISS III, and extramedullary disease, it was recommended that he continue triplet drug therapy until disease relapse or drug intolerance.

Ongoing and Future Trials

The management of RRMM will continue to evolve as paradigms for treating MM change and new treatment options become available. In particular, immunotherapies (ie, approaches that harness the immune system’s ability to fight cancer) are under exploration and some such drugs that are already FDA-approved in other diseases are being tested in MM. Chimeric antigen receptor-T cells (CAR-T), a form of cell-based immunotherapy, have generated tremendous excitement in acute lymphocytic leukemia [66] and are being tested in MM [67]. New analogs of old drugs may offer more effective, less toxic ways to control MM. The role of ASCT is being explored in randomized trials investigating whether ASCT should be pursued early or late in a patient’s MM course. These studies will no doubt further augment the armamentarium of anti-myeloma drugs that have already resulted in the increasingly longer survival we see today in this disease [3,68]. That said, MM remains incurable, and almost all patients who live long enough eventually relapse and die of MM. Hence, further research and progress are critical.