MM-008: A Phase 1 Trial Evaluating Pharmacokinetics and Tolerability of Pomalidomide + Low-Dose Dexamethasone in Patients with Relapsed or Refractory and Refractory Multiple Myeloma and Renal Impairment

Background: Pomalidomide (POM) is indicated for patients (pts) with relapsed or refractory multiple myeloma (RRMM) who received ≥ 2 prior therapies including lenalidomide and bortezomib and demonstrated progression on or within 60 days of completion of the last treatment (Tx). Renal impairment (RI) is a common comorbidity of multiple myeloma (MM) occurring in 20% to 40% of pts (Eleutherakis-Papaikovou, et al. Leuk Lymphom, 2007; Knudsen, et al., Eur J Haematol, 2000). POM is extensively metabolized, with < 5% eliminated renally as the parent drug (Hoffmann, et al., Cancer Chemother Pharmacol, 2013). POM in combination with low-dose dexamethasone (LoDEX) has shown efficacy in pts with RRMM and moderate RI (creatinine clearance [CrCl] < 30-44 mL/min), but pts with severe RI (CrCl < 30 mL/min; serum creatinine> 3 mg/dL) were excluded from most trials (Siegel, et al., Blood. 2012; Weisel, et al., J Clin Oncol, 2013). MM-008 is a multicenter, open-label, phase 1 study assessing the pharmacokinetics (PK) and safety of POM + LoDEX in pts with RRMM and normal or severely impaired renal function.

Methods: Pts withRRMM (≥ 1 prior Tx) and normal kidney function or mild RI (creatinine clearance [CrCl] ≥ 60 mL/min; Cohort A—control arm), severe RI (CrCl < 30 mL/min) not requiring dialysis (Cohort B), and severe RI requiring dialysis (Cohort C) were eligible. Cohort A received POM 4 mg, and Cohort B received POM 2 or 4 mg on days 1-21 of a 28-day cycle, following a 3 + 3 dose-escalation design. Cohort B results informed the 4 mg dosing of Cohort C. All cohorts received DEX 40 mg (20 mg for pts aged > 75 yrs) on days 1, 8, 15, and 22. Tx continued until progression or unacceptable toxicity. Dose-limiting toxicities (DLTs) were defined as any of the following: grade (Gr) 4 neutropenia, febrile neutropenia, Gr 4 thrombocytopenia that is a ≥ 30% decrease in platelets from baseline and requires > 1 platelet transfusion, Gr 3 thrombocytopenia with significant bleeding (requiring hospitalization and/or platelet transfusion), Gr 4 infection, or ≥ Gr 3 other non-hematologic toxicity related to POM. Serial plasma samples were analyzed to generate PK parameters. Updated PK and AE data for all cohorts will be presented.

Results: As of July 17, 2014, updated data for 16 treated pts were available (8 in Cohort A; 3 in Cohort B at 2 mg; 4 in Cohort B at 4 mg; and 1 in Cohort C). Median age was 67 yrs (range, 46-76 yrs), 56% were male, all had Eastern Cooperative Oncology Group performance status 0 or 1, and a median time from diagnosis of 3.8 yrs (range, 0.6-12.5). No DLTs in cycle 1 were reported for any cohort. The most common Gr ≥ 3 adverse events (AEs) were neutropenia, anemia, infection, and fatigue (Table). Median relative dose intensity was consistent across cohorts: 90% (Cohort A), 90% (Cohort B; 2 mg), 100% (Cohort B; 4 mg) and 100% (Cohort C). Three pts discontinued due to AEs (2 in Cohort A and 1 in Cohort B 4 mg); no deaths have occurred during treatment phase.

Conclusion: MM-008 is an ongoing trial prospectively evaluating the PK and safety of POM + LoDEX in pts with RRMM and severe RI. Preliminary PK data support mean dose-normalized exposure in pts with RRMM being similar between those with severe RI and those with no or mild RI at the clinical dose of 4 mg; early tolerability data (after one cycle) are encouraging.

N/A: Not applicable (4 mg POM is approved dose for population)