Bortezomib-Dexamethasone Alone or Plus Cyclophosphamide or Lenalidomide As Second-Line Treatment for Patients with Multiple Myeloma: Final Results From a Phase 2 Study

Bortezomib plus dexamethasone (VD) has been shown to be effective and well tolerated in patients (pts) with multiple myeloma (MM) as frontline induction therapy and in relapsed pts; however, no studies have prospectively assessed VD as second-line therapy. The addition to VD of cyclophosphamide (VDC) or lenalidomide (VDR) may improve efficacy, but with increased toxicities. This phase 2 study evaluated the efficacy and safety of VD, with the addition of C or R for pts with stable disease (SD) after 4 cycles, in pts with relapsed or refractory MM following 1 prior line of therapy. This is the first prospective study of VD as second-line therapy for MM.

Bortezomib-naïve pts aged ≥18 years with measurable MM and no grade ≥2 peripheral neuropathy (PN) who had relapsed/progressed after 1 previous line of therapy received four 21-day cycles of VD (bortezomib 1.3 mg/m², days 1, 4, 8, 11; Dex 20 mg, days 1, 2, 4, 5, 8, 9, 11, 12). Pts achieving at least partial response (PR) then received a further 4 cycles of VD. Pts with SD were randomized to a further 4 cycles of VD, or 4 cycles of VDC (VD + C 500 mg, days 1, 8, 15), or VDR (VD + R 10 mg, days 1–14) for Cycles 5–8. Pts with progressive disease (PD) discontinued treatment. The primary end point was response rate; secondary end points included time to response, duration of response (DOR), safety, and improvement in renal function (defined by the Cockcroft-Gault glomerular function rate [GFR], assessed prior to treatment on day 1, Cycles 1–5).

A total of 189 pts were enrolled; 26 did not receive therapy and were excluded from the safety/ITT population (N=163). Median age was 63 years (range 34–86), 53% were male, 20% had KPS ≤70; median time from prior therapy was 13.9 months. In the ITT population, 52% of pts (84/163) experienced an OR by Cycle 4 as validated by IDMC. Discontinuations were due to toxicity (N=10), death, PD, and other reasons (6 each). Of 135 remaining pts who started Cycle 4 treatment, 120 pts had a response assessment at Cycle 4; according to investigators, 82% of these pts experienced an overall response (OR) and 2.5% had PD; median time to first and best response was 49 and 85 days, respectively. Nineteen pts had SD and were randomized: 7 to VD, 8 to VDC (1 did not continue treatment), 4 to VDR. Only 11 pts received a third drug, C or R, in addition to VD. Due to the high response rate for the first four cycles, the second randomization arm was not completed. 47% (77/163) had continued treatment up to Cycle 8. Based on IDMC response validation as of June 2011, 122 patients had a Best Confirmed Response: 75% OR, 20% SD, and 4% PD. GFR results at Cycle 8 are shown in the Table. In pts who had baseline and on-study assessments, median GFR was 62.2 mL/min at baseline and increased after Cycles 1, 2, 3, 4, 5, 6, 7, and up to Cycle 8 by 4.5, 5.7, 9.4, 8.7, 6.0, 9.6, 8.9, and 5.5 mL/min, respectively. Of the 26 pts with stage migration from baseline GFR to best GFR at Cycle 4, 12 had a renal response (MR renal). Of the 24 pts with baseline GFR <50 ml/min and renal response with stage migration from baseline GFR to best GFR at Cycle 8, 13 had CR renal, 11 had MR renal. Grade 3/4 adverse events (AEs) occurred in 64% of pts; the most common were thrombocytopenia (17%), anemia (10%), and constipation (6%). 40% of pts had serious AEs, and 46%/29%/12% had AEs resulting in dose reductions/discontinuation/death. Overall rates of sensory PN, polyneuropathy, PN (neuropathy peripheral), and motor PN in Cycles 1–8 were 20%, 18%, 13%,and 1% respectively, including 5%, 5%, 4%, and 1% grade 3/4, respectively; 55% of PN events were reversible, with resolution in 43%.

This is the first prospective trial which assessed VD as second-line treatment in MM. VD is effective and well tolerated with less than 10% of pts receiving subsequent C or R added to VD. Overall renal function was shown to improve with treatment. PN was manageable with good reversal rates. VD represents a feasible, active treatment option for pts with relapsed MM. Final efficacy and safety data will be presented.

Dimopoulos:Ortho Biotech: Consultancy, Honoraria; Millennium Pharmaceuticals, Inc: Consultancy, Honoraria. Beksac:Celgene: Honoraria, Speakers Bureau; Janssen-Cilag: Honoraria, Speakers Bureau; Novartis: Honoraria, Speakers Bureau. Allietta:Covance for Janssen-Cilag: Employment. Broer:Janssen-Cilag: Employment. Couturier:Janssen-Cilag: Employment. Angermund:Janssen-Cilag: Employment. Facon:Janssen-Cilag: Consultancy, Honoraria; Celgene: Consultancy, Honoraria.