Management of Relapsed and Refractory Multiple Myeloma

Patient B

A 75-year-old woman with IgA-kappa MM was diagnosed after laboratory testing by her primary care physician incidentally showed an elevated serum total protein level. The MM was intermediate risk, with RISS stage II disease, and with mild renal impairment resulting in an estimated creatinine clearance of 45 mL/min that was felt to be due to MM. She was initially treated with bortezomib and dexamethasone but received only 2 cycles because she developed painful peripheral neuropathy secondary to bortezomib. Bortezomib was stopped and she was then treated with lenalidomide and dexamethasone for 4 cycles. She achieved a complete response and elected to stop treatment due to fatigue. Her fatigue did not improve off treatment. Six months after stopping therapy, an M-spike was detectable at 0.1 g/dL and she developed a new painful lytic lesion in the left humerus.

Patient C

A 59-year-old man with lambda free light chain MM was diagnosed when he presented with acute renal failure requiring dialysis. The disease was RISS-III at diagnosis (high risk), with the t(4;14) genetic abnormality in his MM cells detected on bone marrow aspirate, an abnormality that has been associated with poor prognosis MM [6–8]. The patient was treated with cyclophosphamide, bortezomib, and dexamethasone [9] for 6 cycles, at which point his disease was in a very good partial response (>90% reduction in M-spike) [4], and his renal function had recovered to a new baseline creatinine clearance of 45 mL/min. He then underwent ASCT after melphalan conditioning followed by bortezomib maintenance therapy every 2 weeks. Eight months after ASCT, his lambda free light chain level increased from 1.25 mg/dL to 45 mg/dL and the ratio increased from 4 to 22. Renal function was unchanged and there was stable anemia, with hemoglobin of 10.1 g/dL.

• When should treatment for RRMM commence?

Patients with MM in remission are closely monitored, with clinical and laboratory examinations generally conducted every 1 to 3 months. The history is focused on MM-related symptoms such as increasing bone pain or weight loss, and symptoms of therapy-related toxicity such as fatigue, gastrointestinal distress, or peripheral neuropathy. Laboratory assessment typically includes blood counts and chemistry measurements, as well as measurements of MM-derived monoclonal proteins: SPEP, serum immunofixation (IFE), serum immunoglobulin free light chain measurements, and urine protein electrophoresis and immunofixation (UPEP/urine IFE) [10]. Progressive disease biochemically is defined as a 25% increase in M-spike (at least 0.5 g/dL if the M-spike is in serum or > 200 mg/24 hours if in urine), and/or a rise of greater than 10 mg/dL difference between the involved and uninvolved serum free light chains. Clinically progressive disease is denoted as new evidence of end-organ damage such as a new plasma-cytoma, unexplained hypercalcemia, or worsening anemia due to MM [4]. Many, if not most, patients will have biochemical recurrence identified by laboratory measurements ofmonoclonal proteins before clinical recurrence transpires.

The velocity of relapse can help guide decisions about when to reinitiate therapy. High-velocity disease relapse, meaning rapid rise in monoclonal proteins, is an indicator of more aggressive disease, and treatment should be initiated promptly before development of symptoms [11]. Conversely, low-level, indolent recurrence can often be followed with a “watch and wait” approach to determine how the myeloma will progress over time. Expert guidelines suggest that a monoclonal protein doubling time of 2 months may be an appropriate cutoff for determining high versus low velocity [12], although 2 months is not a firm rule and the decision of when to restart treatment for any given patient with asymptomatic biochemical recurrence should be individualized. Importantly, it is not clear that changing therapy at the time of biochemical recurrence, prior to clinical disease progression, improves outcomes, but clinicians are often nonetheless hesitant to hold therapy in the face of biochemically recurrent MM given the potential for complications, such as a pathologic fracture. In patients with biochemically recurrent MM for whom re-initiation of systemic anti-myeloma therapy is being deferred, one can consider re-initiation of zoledronic acid therapy, since in a randomized controlled trial, zoledronic acid commenced at the time of biochemical relapse resulted in fewer skeletal events as compared to placebo [13].