Efficacy of lenalidomide as salvage therapy for patients with AL amyloidosis

We retrospectively evaluated 55 consecutive patients who received at least one dose of lenalidomide for relapsed/refractory AL amyloidosis. Their median age was 63 years; 72% had heart and 75% kidney involvement and 13% were on dialysis; while 20%, 46% and 34% had Mayo stage -1, -2 and -3 disease, respectively. Median time from start of primary therapy to lenalidomide was 15 months (range 2-100) and median number of prior therapies was 1 (range 1-4); 73% of the patients had prior bortezomib and 42% were bortezomib-refractory. On intent to treat, haematologic response rate was 51% (5.5% CRs, 20% VGPRs) and was 56% versus 40% for patients with and without prior bortezomib and 47% versus 62.5% for bortezomib refractory versus non-refractory patients (p = .351). Organ response was achieved by 16% of evaluable patients (22% renal, 7% liver and 3% cardiac); however, 10 (21%) patients progressed to dialysis. Median survival post lenalidomide was 25 months. Bortezomib-refractory patients had worse outcome (median survival of 10.5 versus 25 months for bortezomib-sensitive patients versus not reached for bortezomib-naive patients, p = .011). Median lenalidomide dose was 10 mg and no patient received the 25 mg dose; however, in 60% a dose reduction was required. Median duration of lenalidomide therapy was 7.2 months and 46% discontinued lenalidomide before completion of planned therapy, mainly due to toxicity (26%) or disease progression/no response (13%). We conclude that although lenalidomide is a major salvage option for patients with relapsed/refractory AL amyloidosis, its toxicity in patients with AL amyloidosis is significant and doses should be adjusted for optimal tolerability.