Venous Thromboembolism with Contemporary Lenalidomide-Based Regimens and Adequate Thromboprophylaxis in Newly Diagnosed Multiple Myeloma: A Systemic Review and Meta-Analysis

Background: Lenalidomide (Len) and low-dose dexamethasone (dex) in combination with proteasome inhibitor (PI) or cytotoxic agent is an integral part of front-line therapy in multiple myeloma (MM). Use of Lenalidomide (Len) in MM had demonstrated an increased risk of venous thromboembolism (VTE) in initial studies which led to the incorporation of routine thromboprophylaxis with Len-based regimens. Existing estimate of VTE incidence from a prior analysis on Len-based regimens in newly diagnosed MM is 0.8 per 100 patient-cycles [Carrier et al. 2011]. However, there is a gap in literature on the incidence of VTE in patients receiving contemporary Len-based combination regimens along with adequate thromboprophylaxis. Hence, we conducted a systematic review and meta-analysis of clinical trials to assess the incidence of VTE with Len-based regimens in newly diagnosed MM patients.

Method: We queried Ovid Medline, Ovid Embase and Cochrane Library databases to obtain relevant studies until March 2018. We included all phase I-III clinical trials testing a Len-based combination regimen for induction +/- consolidation therapy along with protocol-mandated thromboprophylaxis. VTE was defined as deep vein thrombosis or pulmonary embolism (CTCAE Grade 2 or above). Our primary outcome was pooled incidence of VTE events per patient-cycle, which was subsequently converted to VTE events per 100 patient-cycle for ease of comparison with existing literature in MM. We performed meta-analyses with random-effects model using a comprehensive meta-analysis software. Heterogeneity was calculated using I² statistic and a value <25% was considered negligible, up to 50% moderate, and ≥70% was considered substantial heterogeneity. The protocol for this systematic review is registered with PROSPERO [CRD42018102971].

Results: Initial search generated 1069 citations. After screening, 15 clinical trials with 3381 patients were included. Among 15 trials, 4 were phase I/II, 6 were phase II and 5 were phase III. All but one trial used low-dose dex. The pooled incidence of VTE events was 0.4 per 100 patient-cycles [95% CI. 0.3-0.5; I²: 70%]. Incidence rate of VTE in individual studies are summarized in Table I. The Forest Plot is shown in Figure I.

Subsequently, we performed pre-specified subgroup analyses on trials with Len-dex, Len-dex + PI, Len-dex + doxorubicin and Len with Melphalan-Prednisone (MPR). The pooled incidence of VTE per 100-patient cycle with Len-dex was 0.3 [95% CI. 0.1-0.4; I²:92%], Len-dex with PI was 0.9 [95% CI. 0.3-1.6; I^2: 69%], Len-dex with doxorubicin was1.5 [95% CI. 0.7-2.2; I²: 0%] and MPR was 0.3 [95% CI. 0.2-0.4; I²: 0%]. Notably, the incidence of VTE was higher with Carfilzomib-Len-dex when compared to Bortezomib-Len-dex regimens. Two trials with Len-dex + Doxorubicin had a higher rate of VTE irrespective of the dex dose. The most common modes of thromboprophylaxis used were ASA (range, 70-325 mg) and low molecular weight heparin.

Conclusion: Patients with newly diagnosed MM receiving contemporary Len-based regimens have a significant incidence of VTE despite adequate thromboprophylaxis. However, the incidence rate compares favorably with prior estimate. The rate of VTE was highest with the use of Len-dex + Doxorubicin triplet regimen. In the Len-dex+PI subgroup, the incidence of VTE was higher in trials using Carfilzomib-Len-dex compared to Bortezomib-Len-dex regimen. These findings can be clinically applied at an individual level to choose a Len-based combination regimen based on the risk of thrombosis. New prophylactic agents like direct oral anticoagulants should be tested to further decrease the rate of VTE with Len-based combination regimens.

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