Effect of Venous Thrombotic Events on Overall Survival in Multiple Myeloma: Analysis of Thrombotic Events Occurring in E4A03A Randomized Trial of Lenalidomide Plus High-Dose Dexamethasone (RD) Versus Lenalidomide Plus Low-Dose Dexamethasone (Rd) in Newly Diagnosed Multiple Myeloma, a Trial Coordinated by the Eastern Cooperative Oncology Group (ECOG).

Background: Venous thrombotic events (VTE) are a common complication of therapy with the lenalidomide plus dexamethasone regimen. The incidence of VTE with RD is approximately 20%, and can be lowered with the use of effective thromboprophylaxis, avoidance of erythropoietin, and the use of lower doses of dexamethasone. The goal of this study was to determine the impact of VTE on overall survival of patients with newly diagnosed myeloma by studying events occurring in ECOG E4A03 phase III trial of lenalidomide plus high (standard) dose dex (RD) versus lenalidomide plus low dose dex (Rd) in newly diagnosed myeloma (MM).

Methods: Pts with untreated, symptomatic MM were eligible. Pts in the RD arm (Arm A) received lenalidomide 25 mg/day PO days 1–21 every 28 days plus dex 40 mg days 1–4, 9–12, and 17–20 PO every 28 days; pts in the Rd arm (Arm B) received lenalidomide at the same dose plus dex 40 mg days 1, 8, 15, and 22 PO every 28 days. The trial initially did not mandate routine thromboprophylaxis, but recommended that such treatment be considered. After the first 264 patients were enrolled the trial was amended to require mandatory thromboprophylaxis of aspirin for all patients, with a recommendation to use stronger thromboprophylaxis with either warfarin (target INR 2–3) or low molecular weight heparin among patients in the RD arm.

Results: 445 pts (median age, 65 yrs) were accrued; 223 randomized to RD, 222 to Rd. Median follow-up time is 30 months. Overall VTE including deep vein thrombosis (DVT) and pulmonary embolism (PE) occurred in 18.5% of patients; 25.6% in Arm A and 11.4% in Arm B. Rates for the first 4 cycles of treatment were 20.2% in Arm A and 8.2% in Arm B, P<0.01. Rates did not change substantially before and after the prophylaxis amendment. A partial response (PR) or higher was seen in 82.1% of pts who experienced VTE compared with 74.6% of pts who did not experience VTE, P=0.19. Overall VGPR rates also were not inferior. Pts who had VTE, however, had significantly higher other grade 3–5 toxicities such as hyperglycemia (14.6% vs 7.5%, P=0.051), cardiac ischemia (4.9% vs 0.8%, P=0.002), non-neuropathic weakness (13.4% vs 6.4%, P=0.039), infection/pneumonia (17.1% vs 11.1%, P=0.138) and fatigue (18.3% vs 10.5%, P=0.060). In a Cox PH model, VTE status as a time-varying covariate was marginally significant: HR 1.54 95%CI (0.96–2.47), P=0.074, suggesting patients that develop VTE have a higher hazard of death.

Conclusions: The occurrence of VTE may adversely affect the survival of patients with newly diagnosed myeloma receiving Rev-Dex. VTE was associated with a higher frequency of other serious adverse events. Prevention of VTE events is a priority. Besides lowering the dose of dexamethasone, studies investigating optimum thromboprophylaxis are needed.