Management of Relapsed and Refractory Multiple Myeloma

Once MM has progressed beyond the arguable “core drugs” of early-stage MM, namely lenalidomide, bortezomib, carfilzomib, and pomalidomide, off protocol we favor daratumumab monotherapy [56,57]. Other options include panobinostat (given usually with bortezomib) [58] and bendamustine [59], among others.

• Can agents to which the MM was previously refractory be reused?

With the understanding that MM is not a disease defined by a single molecular mutation, but rather clones and subclones, it is reasonable to think that even treatments that have previously failed may be beneficial to patients if they have been off those treatments for some length of time and sensitive subclones reemerge. Additionally, combining the “failed” agent with a new drug may overcome the previously seen refractoriness, as in the case of panobinostat + bortezomib [48]. That said, given the multitude of new treatment options for RRMM and data from such trials as ENDEAVOR as mentioned, revisiting previously used drugs is probably best reserved for second or greater relapses.

• What should be the duration of therapy for RRMM?

There is no evidence to guide duration of therapy in RRMM. Most patients with relapsed disease will be considered for continuous treatment until disease progression, which usually means treatment for 6 to 12 months with full-dose induction, often to maximal response, followed by transition to some form of lower-dose maintenance in which parts of a multi-drug regimen may be eliminated and/or the doses for the remaining drugs may be reduced. Patients with a slow-velocity relapse and no markers of high-risk disease may be suitable candidates for a defined course of treatment without maintenance therapy [11], but most patients nowadays remain on some form of maintenance for RRMM after achieving remission.

• What supportive care is needed in RRMM?

Bone Health

Skeletal-related events, namely fractures, can be devastating in MM. Bisphosphonates have been shown to decrease such events in MM and zoledronic acid has shown a trend toward improved survival, perhaps related to its impact on the bone marrow microenvironment or direct toxicity to myeloma cells [60,61]. It is unclear whether bisphosphonates improve overall survival in the relapsed setting, although zoledronic acid has shown decreased skeletal-related events in the setting of biochemical-only disease progression [13,62]. In active RRMM, our general practice is to resume parenteral bisphosphonate therapy (either zoledronic acid or pamidronate in our U.S. practices) usually every 3 to 4 weeks, depending on the length of the chemotherapy cycle.

Supportive Care

RRMM is a complex disease in which patients often experience a multitude of symptoms and other complications as a result of the disease itself as well as therapy. Aggressive supportive care is of paramount importance. As examples, zoster prophylaxis is required for virtually all patients on proteasome inhibitors, anticoagulation/antiplatelet therapies should be considered for venous thrombotic event prophylaxis, and proton pump inhibitors may be appropriate for these patients who often have a real risk of peptic ulcer disease due to the use of corticosteroids, nonsteroidal anti-inflammatory drugs, and/or aspirin prophylaxis. Attention to dental health is important for patients on bisphosphonates to minimize the risk of osteonecrosis of the jaw. Nutritional problems should be monitored and can arise due to anorexia, dysgeusia, diarrhea, or constipation. Peripheral neuropathy is extremely common and support should be offered in the form of adjusting therapy to minimize risk of worsening it, analgesics if needed, assistive devices to aid in ambulation, and/or physical therapy. Depression and anxiety are understandably prevalent in patients with RRMM, who face an incurable disease that provides constant reminders of its presence due to symptoms, the need for daily pills, or frequent clinic visits for treatment and/or blood product transfusions [63]. Supporting a patient’s emotional health is a vital component of enhancing quality of life in RRMM.