Stringent complete response (sCR) in patients (pts) with newly diagnosed multiple myeloma (NDMM) treated with carfilzomib (CFZ), lenalidomide (LEN), and dexamethasone (DEX).

Abstract

8011 Background: Combination treatment (tx) with CFZ, LEN, and DEX (CRd) is well tolerated and highly active in NDMM. In a phase 1/2 study, CRd provided rapid reduction of disease by 68% after cycle (C) 1 and 94% ≥partial response (PR) at a median of 8C, including 65% ≥very good PR and 53% ≥near CR (nCR), which improved to 79% ≥nCR after C12 (ASH 2011, Abstr 631). Here, we examine the clinical significance of the response rates with longer follow-up. Methods: Pts with NDMM were treated in 28-day (d) C with CFZ 20–36 mg/m2 IV (d1, 2, 8, 9, 15, 16), LEN 25 mg PO (d1–21) and DEX 40/20 mg PO weekly (C1–4/5–8). After C4, autologous stem cell transplant (ASCT) candidates achieving ≥PR could collect stem cells but then continued CRd with the option to proceed to ASCT. After C8, pts received CRd maintenance, using the last tolerated doses, with LEN/DEX at the same schedule but a modified CFZ schedule (d1, 2, 15, 16). Response was assessed by IMWG criteria plus nCR. Results: As of Nov 30, 2011, median follow-up was 14 mo (range 4–25) with 33/53 (62%) pts achieving ≥nCR and 42% sCR. After a median of 13C (range 1–25), 36 pts completed C8 and continued CRd maintenance, 64% achieving sCR. 20/22 pts in CR evaluated for minimal residual disease (MRD) by multiparameter flow cytometry had no MRD. Progression-free survival (PFS) rate was 97% at 12 and 92% at 24 mo. All pts who achieved sCR have maintained response for a median of 9 mo (range 1–20). Extended CRd tx was well tolerated. During CRd maintenance, the most common toxicities (all grades) were lymphopenia (30%), leukopenia (26%), and fatigue (25%), and peripheral neuropathy remained limited (11%, all G1/2). There were no tx discontinuations due to toxicity during maintenance and limited dose modifications (CFZ 19%, LEN 28%, DEX 31%). Conclusions: CRd is highly active in NDMM, providing rapid and deep responses. Extended tx was well tolerated and resulted in improved depth of response with a high sCR rate and a significant proportion of pts without evidence of MRD. Responses were durable with very promising PFS. All pts who achieved sCR remained on CRd with sustained sCR. These results compare favorably to other frontline regimens.