Safety of Treatment (Tx) with Pomalidomide (POM) and Low-Dose Dexamethasone (LoDEX) in Patients (Pts) with Relapsed or Refractory Multiple Myeloma (RRMM) and Renal Impairment (RI), Including Those on Dialysis

Background: RI occurs in ≈ 20%-30% of newly diagnosed MM pts and is associated with poor prognosis (Knudsen et al. Eur J Haematol. 2000; Kyle et al. Mayo Clin Proc. 2003). Data from 2 pivotal trials (MM-002, MM-003) suggested comparable efficacy and tolerability of POM + LoDEX in pts with or without moderate RI (Siegel ASH 2012; Weisel ASCO 2013). However, these trials excluded pts with severe RI. MM-013 (NCT02045017) is a European multicenter, open-label phase 2 study designed to assess the efficacy, safety, and pharmacokinetics of POM + LoDEX in RRMM pts with moderate or severe RI, including those on dialysis.

Methods: The trial is enrolling RRMM pts (N = 80) across 3 cohorts: cohort A (moderate RI, estimated glomerular filtration rate [eGFR] ≥ 30 to < 45 mL/min/1.73 m², n = 33), cohort B (severe RI without dialysis, eGFR < 30 mL/min/1.73 m², n = 33), and cohort C (severe RI requiring dialysis, n = 14). Pts must have MM-related RI and have received ≥ 1 prior Tx (including lenalidomide). POM 4 mg is administered on days 1-21 of a 28-day cycle and LoDEX 40 mg/day (20 mg for pts aged > 75 yrs) on days 1, 8, 15, and 22 until progressive disease (PD) or unacceptable toxicity. At the time of submission of this abstract, 17 pts terminated Tx; this abstract focuses on tolerability in these pts.

Results:This trial is still recruiting; at the time of data cutoff for this abstract, 39 pts were enrolled. Data are included for 17 pts who discontinued Tx. Of all 39 pts, 12 were assigned to cohort A, 18 to cohort B, and 9 to cohort C. The median age of the total population was 72 yrs (range, 52-86 yrs), with 67.7% being male. The median number of prior lines of therapy was 4.0 (3.5 in cohort A, 5.0 in cohort B, and 3.0 in cohort C). This distribution was similar in the 17 pts who discontinued Tx so far (4, 7, and 6 in cohorts A, B, and C, respectively), with a median age of 72 yrs and 58.8% being male. Reasons for discontinuation of Tx were PD (7 pts), adverse events (AEs; 3 pts), death (5 pts: 2 pts due to PD, 2 pts due to infections, 1 pt due to hyperkalemia), and other reasons (2 pts: 1 pt aged 86 yrs with general health problems, 1 pt with increasing RI). Median Tx duration in these pts was 6.9 weeks in cohort A, 12.6 weeks in cohort B, and 12.9 weeks in cohort C. The dosage of POM was reduced to 3 mg in 3 pts (1 patient in each cohort), in all cases due to an AE (thrombocytopenia in 2 pts, pneumonia in 1 pt). However, no further Tx reductions occurred. The most frequent toxicity of any grade in the pts who discontinued was hematologic (82.4% [14 pts]), notably neutropenia in 58.8% (50% in cohort A, 42.9% in cohort B, 83.3% in cohort C), anemia in 52.9% (50% in cohort A, 28.6% in cohort B, 83.3% in cohort C), and thrombocytopenia in 52.9% (75% in cohort A, 14.3% in cohort B, 83.3% in cohort C). Grade 3/4 neutropenia occurred in 47.1%; grade 3/4 thrombocytopenia occurred in 35.3%. Notably, febrile neutropenia was reported in only 1 pt in cohort A. Granulocyte colony-stimulating factor was used in 52.9% of pts. Non-hematologic AEs were less frequent. Infections occurred in 7 pts (41.2%), all of which were pulmonary infections, with the exception of 1 case of nasopharyngitis. Asthenia (23.5%) and fatigue (23.5%) occurred predominantly in cohort C. No thromboembolic events or secondary primary malignancies have been reported to date.

Conclusions: These data suggest that the combination of POM and LoDEX can be safely administered in pts with RI. A starting dose of POM 4 mg can be used throughout all stages of RI, and the side effects seen in this population have been previously reported with POM use (ie, mainly hematologic events and infections). Rates of neutropenia and thrombocytopenia are similar to reports in a non-RI population. Dose modifications should be considered in pts who develop neutropenia and thrombocytopenia; in pts showing signs of infections, dose interruptions may be considered.