Phase I-II Trial of Oral Cyclophosphamide, Prednisone and Lenalidomide (Revlimid®) (CPR) for the Treatment of Patients with Relapsed and Refractory Multiple Myeloma.

Lenalidomide (Revlimid®) and dexamethasone is an effective regimen in relapsed/refractory multiple myeloma (MM) patients (pts), with an overall response rate of 60.6% and median time to progression (TTP) of 13.4 months (Dimopoulos MA, et al, Leukemia 2009 Jul 23 [Epub ahead of print]). Oral cyclophosphamide and prednisone is an older regimen with excellent patient tolerance, and we sought to enhance the efficacy of lenalidomide by adding oral cyclophosphamide and prednisone in this phase I-II trial. The CPR regimen consisted of cyclophosphamide on days 1, 8 and 15; lenalidomide on days 1–21; and prednisone 100 mg every other day in a 28 day cycle. ASA 81 mg/day was given to all pts as DVT prophylaxis. Three dose levels were evaluated using a 3 by 3 dose escalation design. Between 11/2007–07/2009, 31 pts with relapsed/refractory MM who had not previously received lenalidomide were entered onto study. Median age was 61 (40–78) years and 61% were male. Immunoglobulin subtype was IgG in 19 pts (61%), IgA in 8 pts (26%) and light chain only in 4 pts (13%). Median number of prior regimens was 2 (1–5) and 28 pts had undergone previous ASCT, including double transplants in 6 pts. Prior therapy included thalidomide in 9 (29%) and bortezomib in 15 (48%). FISH cytogenetics were available in 13 pts; one had 13q deletion but none had t(4;14) or p53 deletion. At the time of protocol entry, median β 2-microglobulin level was 246 (92–767) nm/L, albumin 39 (34–48) g/L, creatinine 83 (50–126) μmol/L, platelet count 230 (75–337) × 10⁹/L and ANC 2.5 (1.1–6.1) x 10⁹/L. Protocol treatment is summarized in Table 1.

Dose limiting toxicity was not observed during cycle 1 at any dose level. Grade 3–4 toxicities included thrombocytopenia in 5 pts (16%) and neutropenia in 9 pts (29%). These were managed with dose reduction and/or growth factor support. Four episodes of febrile neutropenia occurred. Other grade 3–4 non-hematologic toxicities included abdominal pain/bacteremia in 1 pt in cohort 1; hypokalemia in 1 pt in cohort 2; and DVT in 2 pts, dizziness in 2 pts and fatigue in 1 pt in cohort 3. Using the International uniform response criteria (Durie BG, et al, Leukemia 2006; 20:1467–1473), the best response was documented at a median of 6 (1–5) cycles and included the following: dose level 1 (1 CR, 2 PR); dose level 2 (1 VGPR, 2 PR); dose level 3 (5 CR, 9 VGPR, 9 PR, 1 MR and 1 stable disease). At a median follow-up (F/U) of 12 (8–21) months, 20 pts remain on study, 2 have withdrawn and 9 pts have progressed at a median of 9 (4–13) months; only 1 one has died (due to MM). We conclude: 1) the combination of full doses of the agents in CPR can be given in a 28 day cycle with minimal toxicity; 2) the overall response rate (CR + VGPR + PR) in 31 pts to date is 93%; 3) at a median F/U of 1 year, only 9 pts (29%) have progressed; 4) longer follow-up is required to assess the TTP and survival of the CPR regimen.

Reece:Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau. Off Label Use: Lenalidomide in combination with drugs other than dexamethasone. Anglin:Celgene: Honoraria. Chen:Celgene: Honoraria, Research Funding. Kukreti:Celgene: Honoraria. Mikhael:Celgene: Honoraria. Trudel:Celgene: Honoraria.