Differentiation Syndrome Associated With Enasidenib, a Selective Inhibitor of Mutant Isocitrate Dehydrogenase 2: Analysis of a Phase 1/2 Study.

Importance: Enasidenib mesylate, a mutant isocitrate dehydrogenase 2 (IDH2) protein inhibitor that promotes differentiation of leukemic myeloblasts, was recently approved by the US Food and Drug Administration for use in relapsed/refractory (R/R) mutant IDH2 acute myeloid leukemia (AML). During the first study of enasidenib in humans, a minority of patients with advanced myeloid neoplasms experienced unexpected signs/symptoms of a differentiation syndrome (DS), a potentially lethal entity. Objective: To characterize IDH-inhibitor-associated DS (IDH-DS) and its effective management. Design, Setting, and Participants: Using data obtained from a multicenter, open-label, pivotal phase 1/2 study of enasidenib, a differentiation syndrome review committee retrospectively evaluated potential cases of IDH-DS in enasidenib-treated patients with R/R AML. Data were collected between August 27, 2013, and October 14, 2016. The committee identified and agreed on signs and symptoms characteristic of IDH-DS and developed an algorithm for identification and treatment. Among 281 patients with R/R AML enrolled in the trial, the committee identified 72 patients for review based on investigator-reported cases of DS (n = 33) or reported adverse events or signs and symptoms characteristic of IDH-DS. Interventions: Treatment with enasidenib at a dosage of 50 to 650 mg/d was evaluated during the dose-escalation phase, and a dosage of 100 mg/d was used in the phase 1 expansion and phase 2, all in continual 28-day cycles. Main Outcomes and Measures: Unexpected adverse events of IDH-DS during the phase 1/2 study. Results: Thirty-three of the 281 patients (11.7%) were identified as having possible or probable IDH-DS. Median age of those 33 patients was 70 years (range, 38-80 years); 20 (60.6%) were male. The most frequent manifestations were dyspnea, fever, pulmonary infiltrates, and hypoxia. Median time to onset was 30 days (range, 7-129 days). Patients who experienced IDH-DS were less likely to have less than 20% bone marrow blasts (6% vs 22%, P = .04) and more likely to have undergone fewer previous anticancer regimens (median, 1.0 [range, 1-4] vs 2.0 [range, 1-14], P = .05) at study entry than those who did not. Thirteen patients (39.4%) had concomitant leukocytosis. Isocitrate dehydrogenase differentiation syndrome was effectively managed with systemic corticosteroids. The enasidenib regimen was interrupted for 15 patients (45.5%), but permanent discontinuation of treatment was not required. Conclusions and Relevance: Isocitrate dehydrogenase differentiation syndrome is a recognizable and potentially lethal clinical entity, occurring in approximately 12% of enasidenib-treated patients with mutant-IDH2 R/R AML. It requires prompt recognition and management. As use of mutant IDH inhibitors increases, these findings and recommendations are increasingly germane to care of patients with mutant-IDH neoplasms. Trial Registration: clinicaltrials.gov Identifier: NCT01915498.

Subsequent primary malignancies among multiple myeloma patients treated with or without lenalidomide.

Risk of subsequent primary malignancies (SPMs) associated with lenalidomide therapy in multiple myeloma (MM) patients, outside the context of melphalan-based therapy is not established. We assessed the risk of SPMs in lenalidomide treated MM patients (n = 1653) at Moffitt Cancer Center (2004-2012) outside the context of melphalan-based induction therapy and post-melphalan maintenance therapy, via (1) cohort analysis and (2) nested case-control study. Incident SPMs (n = 51) were matched to controls (n = 102) on age at MM diagnosis, gender, follow-up time, and date of diagnosis. Incidence of SPM differed significantly (p = 0.0038) between MM patients treated with and without lenalidomide (5-year incidence estimates of 3.2 and 6.2%, respectively), although not significant after adjustment for age and year of diagnosis (HR = 0.82, 95%CI = 0.43-1.57). Lenalidomide treatment was inversely associated with SPM in the nested case-control analysis (OR = 0.03, 95%CI = 0.002-0.34). In this large cohort of MM patients, lenalidomide treatment was not associated with an increased risk of SPM.

Subsequent primary malignancies and acute myelogenous leukemia transformation among myelodysplastic syndrome patients treated with or without lenalidomide.

The few studies that have examined rates of acute myeloid leukemia (AML) transformation in lenalidomide-treated myelodysplastic syndrome (MDS) patients have been limited to deletion 5q MDS. The association between lenalidomide and subsequent primary malignancies (SPMs) in MDS patients has not been evaluated previously. We conducted a retrospective cohort study to evaluate the risk of both SPM and AML in association with lenalidomide. A cohort of MDS patients (n = 1248) treated between 2004 and 2012 at Moffitt Cancer Center were identified, and incident cases of SPM and AML transformation were ascertained. Using a nested case-control design, MDS controls were 1:1 matched to SPM (n = 41) and AML (n = 150) cases, on age and date of MDS diagnosis, gender, follow-up time, IPSS, and del (5q). Associations between lenalidomide and (1) SPM incidence and (2) AML transformation were estimated with hazards ratios (HR) and 95% confidence intervals (CIs) in the cohort and odds ratios (OR) in the case-control analysis. SPM incidence did not differ significantly between cohort MDS patients treated with (0.7 per 100 person-years) or without lenalidomide (1.4 per 100 person-years) (HR = 1.04, 95% CI = 0.40-2.74), whereas a significantly reduced SPM risk was observed in the case-control sample (OR = 0.03, 95% CI = <0.01-0.63). Lenalidomide was not associated with AML transformation in the cohort analysis (HR = 0.75, 95% CI = 0.44-1.27) or in the case-control analyses (OR = 1.16, 95% CI = 0.52-2.56), after adjustment for potential confounders. Lenalidomide was not associated with increased risk of SPM or AML transformation in a large cohort of MDS patients mostly including nondeletion 5q MDS.

Safety and efficacy of single-agent lenalidomide in patients with relapsed and refractory multiple myeloma.

Lenalidomide plus dexamethasone is effective for the treatment of relapsed and refractory multiple myeloma (MM); however, toxicities from dexamethasone can be dose limiting. We evaluated the efficacy and safety of lenalidomide monotherapy in patients with relapsed and refractory MM. Patients (N = 222) received lenalidomide 30 mg/day once daily (days 1-21 every 28 days) until disease progression or intolerance. Response, progression-free survival (PFS), overall survival (OS), time to progression (TTP), and safety were assessed. Overall, 67% of patients had received 3 or more prior treatment regimens. Partial response or better was reported in 26% of patients, with minimal response 18%. There was no difference between patients who had received 2 or fewer versus 3 or more prior treatment regimens (45% vs 44%, respectively). Median values for TTP, PFS, and OS were 5.2, 4.9, and 23.2 months, respectively. The most common grade 3 or 4 adverse events were neutropenia (60%), thrombocytopenia (39%), and anemia (20%), which proved manageable with dose reduction. Grade 3 or 4 febrile neutropenia occurred in 4% of patients. Lenalidomide monotherapy is active in relapsed and refractory MM with acceptable toxicities. These data support treatment with single-agent lenalidomide, as well as its use in steroid-sparing combination approaches. The study is registered at http://www.clinicaltrials.gov as NCT00065351.