Pomalidomide (POM) with Low-Dose Dexamethasone (LoDex) in Patients (Pts) with Relapsed and Refractory Multiple Myeloma Who Have Received Prior Therapy with Lenalidomide (LEN) and Bortezomib (BORT): Updated Phase 2 Results and Age Subgroup Analysis

New antimyeloma treatments that re-establish tumor response are required to improve survival for pts with advanced, treatment-refractory MM. The MM-002 phase 2 study evaluated the safety and efficacy of oral pomalidomide, in combination with low-dose dexamethasone (POM+LoDex), in pts with relapsed and refractory multiple myeloma (RRMM) who have who have received ≥2 prior therapies including LEN and BORT (Richardson PG, et al. Blood 2011;118:abs 634). Updated results from March 2012 for pts and the outcomes of subgroup analyses are presented.

Eligible pts with MM who had received at least 2 prior therapies (including LEN and BORT) and had disease progression within 60 days of their last treatment were randomized (1:1 ratio) to either POM+LoDEX (POM, 4 mg/day for days 1–21 of a 28-day cycle; LoDex, 40 mg/week) or POM alone. At progression, pts receiving POM alone could receive POM+LoDEX at investigator's discretion. Pts aged over 75 years received LoDex, 20 mg/week. All pts received mandatory thromboprophylaxis (daily low-dose aspirin). Pts were stratified within each treatment group according to age. The key efficacy endpoints included the objective response rate using European Bone Marrow Transplantation (EBMT) criteria, duration of response, progression free survival (PFS) and overall survival (OS), and safety. This updated analysis focused on pts on the POM+LoDex arm.

The intention-to-treat efficacy analysis included 113 pts in the POM+LoDex group. The mean age of pts treated with POM+LoDex was 64 years (range, 34–88); 99 pts (88%) were aged ≤75 years.

Response rates, median duration of response, and age subgroups are presented in the Table. Median PFS and OS were 4.6 months (mos) and 16.5 mos, respectively, in the POM+LoDex group overall. In the age subgroup analysis of pts treated with POM+LoDex, the median PFS was 4.7 mos in pts aged ≤65 years, and 3.7 mos in pts >65 years. Median OS was 19.7 mos in pts aged ≤65 years and 11.8 mos in pts >65 years.

The most common grade 3 or 4 adverse events (AEs) occurring in >5% of pts were neutropenia (41%), anemia (22%), pneumonia (22%), thrombocytopenia (19%), fatigue (14%), dyspnea (13%), leukopenia (10%), back pain (10%), and urinary tract infection (9%). AEs led to at least one dose reduction in 26% of pts; neutropenia was associated with a dose reduction in 4% of pts. Overall, 78% of pts who developed grade 3 or 4 neutropenia used G-CSF during study treatment. There were no reports of grade 3 or 4 peripheral neuropathy (PN); grade 1 or 2 PN occurred in 7% of pts treated with POM+LoDex. Deep vein thrombosis (any grade) occurred in 2 pts (2%), both aged ≤65 years. Grade 3 or 4 neutropenia occurred in 46% of pts aged ≤65 years and in 35% of pts aged >65 years. Despite this, only 1 pt in each age group developed febrile neutropenia (2%).

The mean relative dose intensity (dose intensity/planned dose intensity) was 0.9 in both pt groups of ≤65 years and > 65 years receiving POM+LoDex. Overall, 21 pts (19%) of the POM+LoDex group died during the study. The most common cause of death was progressive MM (52%; only in 14% of all cases was it due to disease progression); other causes of death (48%) included infections, cerebral/intracranial/subarachonoid hemorrhage, acute respiratory distress syndrome, and suicide in one pt with a history of severe depression.

POM, 4 mg/day for days 1–21 of a 28-day cycle in combination with LoDex, is clinically effective and generally well tolerated in pts with RRMM who have received multiple prior treatments including LEN and BORT. POM+LoDex represents an important potential new treatment option for pts with advanced MM and appears active in both younger and older pts, with tolerability similar across different age groups. Phase 3 studies of POM+LoDEX in combination with other agents (e.g. bortezomib) are ongoing.

Jagannath:Millennium Pharma: Honoraria, Membership on an entity's Board of Directors or advisory committees; Merck Sharp & Dohme: Honoraria, Membership on an entity's Board of Directors or advisory committees; Onyx Pharma: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees. Off Label Use: Pomalidomide is an investigational drug and is not approved for the treatment of patients with any condition. Hofmeister:Celgene: Advisory Board Other, Honoraria. Siegel:Onyx: Advisory Board, Advisory Board Other, Honoraria, Speakers Bureau; Millennium Pharma: Advisory Board, Advisory Board Other, Honoraria, Speakers Bureau; Celgene: Advisory Board Other, Honoraria, Speakers Bureau; Merck: Advisory Board, Advisory Board Other, Honoraria, Speakers Bureau. Vij:Onyx: Consultancy, Research Funding; Millennium Pharma: Speakers Bureau; Celgene: Consultancy, Research Funding, Speakers Bureau. Lonial:Millennium, Celgene, Novartis, BMS, Onyx, Merck; all < $10,000 per year and disclosed to my institution: Consultancy. Anderson:Acetylon, Oncopep: Scientific Founder, Scientific Founder Other; Celgene, Millennium, BMS, Onyx: Membership on an entity's Board of Directors or advisory committees. Chen:Celgene: Employment, Equity Ownership. Zaki:Celgene: Employment, Equity Ownership. Richardson:Celgene, Millennium, Johnson & Johnson: Advisory Board Other.