Activity and safety of lenalidomide and dexamethasone in patients with multiple myeloma requiring dialysis: a Spanish multicenter retrospective study.

To the Editor: Lenalidomide is an immunomodulating agent that has been shown to be a highly active agent in the management of patients with multiple myeloma (MM) (1, 2), but most studies excluded patients with a serum creatinine level >2.5 mg ⁄dL. Experience with lenalidomide (3) in the management of patients with MM and renal impairment is scarce. We present the results of a retrospective study in a group of 15 patients from 11 Spanish centers with MM and severe renal impairment requiring dialysis and receiving lenalidomide-based therapy at the time of study entry. Response criteria were based on the International Myeloma Working Group (IMWG) criteria (4). Patient features at the time of inclusion are summarized in Table 1. Two patients had renal impairment requiring dialysis before myeloma diagnosis. The remaining thirteen patients developed renal failure at diagnosis or during the evolution of the disease, and it was because of MM (six patients), drug-related (two patients), secondary to underlying diabetes (two patients), and secondary to a tumoral lysis syndrome because of bortezomib (one patient). Finally, no data were available in the remaining two patients. Thirteen (86%) patients received lenalidomide at a dose of 15 mg ⁄d, three times a week after dialysis and in combination with dexamethasone (Table 1). Patients received a median of eight cycles (range, 1–28) of lenalidomide treatment. Hematological toxicity was the toxicity more frequently seen and required dose reduction in eight (53%) patients, and granulocyte-colony stimulating factor prophylaxis in seven (47%). Ten patients developed neutropenia (6 grade 3–4), and seven (47%) patients presented thrombocytopenia (1 grade 3). Finally, two (13%) patients presented grade 2 anemia. Six (40%) patients developed seven infectious episodes during the study period, five of them within the first four cycles of therapy. There were four (57%) bacteremias, two (29%) pneumonias, and one (14%) central venous line infection (Table 2). Other non-hematological complications are shown in Table 2. There were no thromboembolic complications. Overall response rate was 60% (nine patients), with four (29%) achieving complete response (CR), one (7%) patient very good partial response, and four (29%) patients partial response. Median time to best response was 4 months. With a median follow-up of 13 months (range 1–28), median progression-free and overall survival was 15 and 20 months, respectively. Among responding patients, median duration of response has not been reached. Seven (47%) patients have died because of disease progression (five patients) and of infectious complications (two patients) and eight (53%) are still alive, seven with continuous lenalidomde treatment and one off therapy because of disease progression. Renal function remained stable in all but one patient who was spared from dialysis after achieving partial response 3 months after starting treatment. Currently, there is no standard treatment for patients with MM and renal failure requiring dialysis. Results with new agents such as thalidomide and bortezomib are disparate. With thalidomide, experience is scarce and has been associated with a high incidence of hyperkaliemia in patients with serum creatinine >3 mg ⁄dL (5, 6). Better results have been reported with bortezomib-based regimens, with a response rate of 75% with 30% of CR + near CR and with a toxicity profile similar to that observed in patients with normal renal function (7). Lenalidomide has been shown to undergo substantial elimination via the kidneys, and recently, encouraging results have been reported in patients with different degrees of renal impairment (3). However, no data in patients with MM and advanced renal failure requiring dialysis are available. Our report is the first one including this high-risk subgroup of patients with MM and show a response rate of 65% with 29% of CR like that seen in patients with normal renal function (1, 2). Importantly, progression-free and overall survival was also similar to that reported in patients without significant renal failure (1, 2). Finally, among responding patients, median duration of response has not been reached, pointing that durability of response is also comparable to those of patients with MM with normal renal function in the relapsed setting (1, 2). In our series, as in other studies including lenalidomide in patients with mild renal impairment (3, 8, 9), doi:10.1111/j.1600-0609.2010.01500.x