Final Results of a Frontline Phase 1/2 Study of Carfilzomib, Lenalidomide, and Low-Dose Dexamethasone (CRd) in Multiple Myeloma (MM)

In relapsed and/or refractory MM, the combination of carfilzomib (CFZ) with lenalidomide (Len), and low-dose dexamethasone (Dex) (CRd) has shown very promising efficacy (78% ≥partial response [PR], 40% ≥very good partial response [VGPR], and 24% CR/nCR) and good tolerability including a low rate of peripheral neuropathy (Wang et al, ASCO, 2011). In a Phase I/II study of newly diagnosed MM, the regimen was well tolerated in the Phase I portion of the study up to a maximum dose of CFZ 36 mg/m², Len 25 mg, and Dex 40 mg, and very active with 96% ≥PR, 70% ≥VGPR, and 55% CR/nCR (Jakubowiak et al, ASH 2010). The lack of overlapping toxicities has allowed these agents to be used at full doses and for extended periods. Here we report the results for all patients (pts) enrolled in both phases of this first prospective trial of CFZ combination in new MM.

In the initial eight 28-day cycles, pts were treated with CFZ at 20 mg/m², 27 mg/m² (Phase I), and 36 mg/m² (Phase I and II), given IV on days 1, 2, 8, 9, 15 and 16, Len at 25 mg PO (days 1–21), and Dex at 40/20 mg PO weekly (cycles 1–4/5–8). Pts achieving ≥PR could proceed to stem cell collection (SCC) using growth factors alone (protocol recommendation) and autologous stem cell transplant (ASCT) after 4 cycles. Per protocol, ASCT candidates were offered the option to continue CRd treatment after SCC. After 8 cycles, pts received 28-day maintenance cycles of CFZ (days 1, 2, 15, 16), Len days 1–21, and Dex weekly at the doses tolerated at the end of 8 cycles. Responses were assessed by IMWG criteria with the addition of nCR.

Enrollment was completed (53 pts): 4 pts at CFZ 20 mg/m², 13 at CFZ 27 mg/m² and 36 at CFZ 36 mg/m² (18 in Phase I and 18 in Phase II). Median age was 59 years (range 35–81; 23 pts ≥65), 60% had ISS stage II/III, and 33% (of 49 with available data) had unfavorable cytogenetics: del 13 or hypodiploidy by metaphase, or t(4;14), t (14;16), del 17p by FISH. As of June 30, 2011, toxicity data (cycles 1–8) were available for 51 pts. Hematologic toxicities were reversible and included Grade (G) 3/4: anemia (18%), neutropenia (12%), and thrombocytopenia (10%). The most common non-hematologic toxicities (all G) were hyperglycemia (76%), hypophosphatemia (61%), and infection (53%). G3/4 non-hematologic AEs included hyperglycemia (24%), DVT/PE while on ASA prophylaxis (10%), infection (6%), and mood alteration (2%). PN was limited to G1/2 sensory (24%). Forty-five pts continue treatment with 22 pts in the maintenance phase. Six pts discontinued treatment: 2 proceeded to ASCT, 1 due to toxicity, and 3 due to events unrelated to treatment or per pt wish. The majority of pts did not require dose modifications, either in the initial (31%) or in the maintenance (25%) phase. After a median of 8 cycles (range 1–20), the best responses per IMWG criteria for 49 response-evaluable pts (all pts who completed 1+ cycle) are shown in the Table. Responses were rapid with 46/49 pts achieving at least PR after 1 cycle, and improved with the duration of treatment reaching 100% ≥PR after 4 cycles and 100% ≥VGPR, 79% CR/nCR after 12 cycles. Responses were deep even at the 2 lower dose levels with the majority of pts at 36 mg/m² still early in treatment. Responses in pts with unfavorable cytogenetics were similar to response rates in all remaining pts and included a 100% ≥PR in 6 pts with del 17p. Twenty-four pts proceeded to SCC after a median of 5 cycles of CRd (range 4–9); using growth factors only in 23 pts and cyclophosphamide and growth factors in 1 pt, with a median 6.55 × 10⁶ CD34+ cells/kg collected (range 3.75–9.6); all resumed CRd treatment. After a median of 9.5 months of follow-up, only 1 pt has progressed, and all are alive

CRd is highly active and well-tolerated allowing the use of full doses for an extended time in newly-diagnosed MM pts with limited need for dose modification. Responses are rapid and improve over time reaching 100% ≥VGPR and early time-to-event data are very encouraging. These results compare favorably to the best frontline regimens in MM.

Jakubowiak:Bristol-Myers Squibb: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Onyx Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees; Millennium Pharmaceuticals, Inc.: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Celgene: Consultancy, Honoraria, Speakers Bureau; Ortho Biotech: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Exelixis: Consultancy, Honoraria. Off Label Use: Use of the investigational agent carfilzomib, proteasome inhibitor, in the treatment of relapsed and/or refractory multiple myeloma. Jagannath:Millennium: Honoraria; Celgene: Honoraria; Onyx Pharmaceuticals: Honoraria; Merck: Honoraria; OrthoBiotec.Imedex: Membership on an entity's Board of Directors or advisory committees; Medicom World Wide: Membership on an entity's Board of Directors or advisory committees; Optum Health Education: Membership on an entity's Board of Directors or advisory committees; PER Group: Membership on an entity's Board of Directors or advisory committees. Vesole:Celgene: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Millennium: Speakers Bureau. Hussein:Celgene Corporation: Employment. Leveque:Onyx Pharmaceuticals: Employment. Vij:Onyx Pharmaceuticals: Consultancy, Research Funding; Celgene: Research Funding, Speakers Bureau; Millennium: Speakers Bureau.