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Introduction Bortezomib, a proteasome inhibitor and lenalidomide (Len), an immunomodulatory drug are the backbone of established treatment regimens for newly diagnosed MM. Patients with dual-refractory (refractory to both bortezomib and lenalidomide) disease have a poor prognosis with overall survival estimated to be less than one year. Pomalidomide (Pom) has distinct anticancer, antiangiogenic and immunomodulatory properties and has demonstrated synergistic antiproliferative activity in combination regimens. The aim of our study is to compare different Pom based regimens to identify the most effective regimen for relapsed refractory multiple myeloma (RRMM) patients. Methods A comprehensive literature search was performed on PubMed, Cochrane library, Web of Science, Embase and AdisInsight databases on 03/29/2018 which identified a total of 1374 studies. We included phase II/III clinical trials on pomalidomide based regimens that have clearly documented efficacy outcomes. All statistical analyses were performed using Comprehensive Meta-analysis (CMA) Version 3. We used the Cochrane Q statistics (p0.05 or I2 >50%). Studies were classified into subgroups according to the therapeutic regimen: dual and triplet combinations. A separate stratified analysis of triplet regimens based on type of regimen was also performed. Results A total of 35 studies (n = 4623 patients) were included. The most commonly studied regimen was Pom + LoDex (Low dose dexamethasone) with a total of 16 studies on this regimen. All patients included in our study had ≥ 2 prior lines of therapy. Mean number of prior lines of therapy was 6. Most patients were lenalidomide refractory, with 10 patient cohorts of 100% refractoriness and 8 cohorts of ≥ 90% refractoriness. Pooled analysis showed an overall response rate (ORR) of 47.1% across all Pom regimens including both doublet and triplet regimens. An I2 value of 87.3 was found, indicating high heterogeneity across all Pom regimens. With Pom-LoDex, pooled ORR was found to be 35.7% and mean OS 14.37 months. With triplet regimens, pooled ORR was found to be 61.9%. In a separate stratified analysis of triplet regimens based on type of regimen, pooled ORRs with few selected regimens were as follows; Bort-Pom-LoDex (pooled ORR 83.5%, mean PFS 15.7 months [mos]), CFZ-Pom-LoDex (pooled ORR 77.1%, mean PFS 15.3 mos), Pom-LoDex-bendamustine (pooled ORR 74.2%), Pom-Dex-daratumumab (pooled ORR 64.5%), Pom-LoDex-cyclophosphamide (pooled ORR 59.4%, mean PFS 9.5 mos), Pom-LoDex-doxorubicin (pooled ORR 32%). Most frequently reported adverse event with Pom based regimens was myelosuppression. Mean incidences of grade ≥3 hematologic adverse events were neutropenia (47.6%), anemia (26.5%), and thrombocytopenia (20.8%). Mean incidences of grade ≥3 non-hematologic adverse events were infections (29.1%), pneumonia (13.8%) and fatigue (10%). Most of the studies used pomalidomide 4mg daily dosing. Lacy et al. suggested no advantage of 4mg pomalidomide over 2 mg daily dosing. Conclusion From results of pooled analysis, we can infer that triplet combinations of Pom yield almost double response rates (pooled ORR 61.9%) when compared to dual combination of Pom-LoDex (pooled ORR 35.7%). Among three drug combinations, Bort-Pom-LoDex (pooled ORR 83.5%) and CFZ-Pom-LoDex (pooled ORR 77.1%) seem to produce better outcomes. Our study provides useful insight into relative efficacy of various Pom regimens for treatment of RRMM patients. Several trials involving various MoAbs like nivolumab, daratumumab, elotuzumab, isatuximab and pembrolizumab in combination with Pom-LoDex are currently ongoing. Pomalidomide has an acceptable safety profile. Most common treatment emergent adverse events were myelotoxicity and infections that can be effectively managed with supportive care and dose modifications. Disclosures No relevant conflicts of interest to declare.

Background: Elotuzumab (elo) is a humanized monoclonal antibody, which has been approved by the FDA for use in combination with lenalidomide (lena) and dexamethasone (dexa) in patients (pts) with relapsed and refractory multiple myeloma (RRMM). Elotuzumab is effective as a single agent, as well as in combination for multiple myeloma treatments, supporting the use of elo in pts with RRMM and newly diagnosed multiple myeloma (NDMM) pts. Method: After review of literature using database searches was done on 6/27/18 (Pubmed, Embase, Cochrane Library, Web of Science and Clinical Trials.gov), 9 prospective and 1 retrospective study with 1128 enrolled pts met the inclusion criteria to date in RRMM and 2 clinical trials including 123 pts in NDMM (Table 1). CMA software v.3 was used for meta-analysis. A random-effect model was applied. Result: Regimens used in RRMM: Based on pooled analysis (95% CI), an overall response rate (ORR) of 66% (54-76.2) was calculated in 685 evaluable pts treated with elo based regimens in RRMM (Figure 1). Most common grade (G) ≥ 3 hematological adverse events (HAE) and non-hematological adverse events (NHAE) based on regimen were calculated using pooled analysis in RRMM pts (Table 2). Anemia was noted in 12.1% ( 7.7-18.6) in 559 pts, while neutropenia in 14.5% (7.5-26.4) out of 591 pts and thrombocytopenia (tcp) in 11.9% (7.9-17.4) in 198 evaluable pts. Diarrhea 5.5% (3.6-8.3), pyrexia 2.4% (1.5-4), peripheral neuropathy (PN) 8.4% (3.8-17.8) were measured in 626, 668 and 143 pts respectively. Elotuzumab as monotherapy: 1 study (n=34) evaluated the efficacy of elo as single agent in RRMM. The median age, time from diagnosis and number of prior therapies were 64.5 years (y) (46-87), 4.4 y (0.9-12.8) and 4.5 y (2-10) respectively. It produced an ORR of 1.4% (0.1-19.1 95% CI) in 34 evaluable pts. Adverse events recorded were pyrexia and fatigue in 17.6% and 8.8% pts respectively. Elotuzumab in two drug regimen: In RRMM, 2 clinical trials (n=49) evaluated the efficacy (95% CI) of elo, ORR of 25% (4.1-72.3) was calculated. The best PFS (progression free survival) produced was in combination of elo 20 mg with bortezumib (bort) 1.3mg/m2 of 9.46 months as compared to 1.8 months when elo10mg/kg + dexamethasone (dexa) 28mg was used. In our analysis for safety, common G≥ 3 HAE calculated were, thrombocytopenia 8.7% (3.3-21.1) n=49, neutropenia 10.7 % (3.5-28.4) n=28 pts and anemia 7.1% (1.8-24.5) n=28 pts. NHAE included diarrhea 1.7% (0.1-22.3), PN 10.7% (3.5-28.4), pyrexia 1.7% (0.1-22.3) in 28 evaluable pts each. Elotuzumab in three drug regimen: In RRMM, 10 clinical trials including 602 pts evaluated the efficacy of elo as a part of triple drug regimen, producing an ORR of 72.2% (54-76.2). The best results were produced with the combination of elo 10-20mg/kg + lenalidomide (lena) 25mg + dexa 40mg producing a PFS of 32.2 mo and 28.62 mo in its phase I and II cohorts respectively. Based on pooled analysis (95% CI) common HAE calculated were neutropenia 17.5% (7.6-35.4) in n=563, thrombocytopenia 12.7% (8.2-19.4) in n=149 and anemia 13% (8-20.5) in n=531 pts. Common G ≥ 3 NHAE estimated were diarrhea 5.7% (3.7-8.6), PN 6.6% (2-19.2), pyrexia 2.5% (1.5-4.1) in 598, 115 and 640 pts respectively. Elotuzumab based regimen in NDMM: A currently ongoing clinical trial NCT02272803 has produced promising results in NDMM pts. As a part of three drug regimen with dose of elo 10mg/kg-20mg/kg, lena 25mg, dexa 20mg in 40 pts produced an ORR of 87.5% (73.2-95.8) versus control group of lena 25mg plus dexa 40mg in 42 pts with an ORR of 73.8% (58-86.1). The PFS rate recorded at 1 year was 93% (79-98%) and 91% (73-97%) respectively. The HAE G ≥ 3 included, neutropenia 18% and leukopenia 15%. In another study with 41 pts, elo was used in combination with lena, bort and dexa producing an ORR of 100% and greater than grade 3 adverse events including Tcp 15%, PN 2%. Conclusion: Results produced in our study suggest that elotuzumab is highly effective when used in pts with RRMM and NDMM. Combination regimens for elo produces an ORR ranging from 79-83% with elo + lena+ dexa, proving that the best results were produced by three drug regimens. Large prospective studies are required to evaluate efficacy and safety of elotuzumab in combination therapies. Disclosures No relevant conflicts of interest to declare.