Promising Clinical Efficacy and Toxicity Profile of Isatuximab Based Regimens for Treatment of Newly Diagnosed and Relapsed/Refractory Multiple Myeloma: A Systematic Review
Authors: Shah Zunairah , Shafqat Madeeha , Jamil Faiza , Malik Mustafa Nadeem , Rafae Abdul , Aslam Shehroz , Qureshi Anum , Sadiq Maryam , Abu Zar Muhammad , Kamal Ahmad , Selene Insija Ilyas , Samuel Sharoon , Riaz Rida , Lakhani Midhat , Anwer Faiz 
Published: October 2019

Abstract
Introduction:
Despite the recent advancements in the treatment of multiple myeloma (MM), there is a constant need of newer therapies in order to treat the complex issue of the disease relapse and refractory disease. Isatuximab (ISA) is a non-Food and Drug Administration (FDA) anti-CD38 monoclonal antibody that acts through immune cell engagement and direct tumor targeting. We report efficacy & toxicity of ISA in newly diagnosed MM ((NDMM) as well as relapsed, refractory MM (RRMM) patients (pts).
Methods:
Following Prisma guidelines, we performed a comprehensive literature search on articles published after January 2012 using PubMed, Embase, Cochrane Library, Web of Science and Clinicaltrials.gov. On initial search, 246 articles were found and after a detailed screening, 6 completed and 11 ongoing phase I/II/III studies were included.
Results:
A total of 249 pts were included. Two hundred thirty-four pts had RRMM while 15 pts had NDMM, overall response rate (ORR) was 37.60% and 87% respectively. In a phase I trial involving 34 pts with RRMM, single-agent ISA (1-20 mg/kg) was given. The median age of pts was 64 years (y) [range (r) = 38-85]. The overall response rate (ORR) was 24% with a partial response (PR) in 18% pts. The most common adverse events (AEs) were nausea (34%), fatigue (49%), fever (29%) and headache (26%) and upper respiratory infection (23%). In a phase II trial, 97 pts with RRMM were stratified into 4 groups. Single-agent ISA [3mg/kg, every 2 week,(Q2W); 10 mg/kg, Q2W - every 4 weeks (Q4W); 10 mg/kg (Q2W), 20 mg/kg (QW-Q2W)] was given. The median age of pts was 62.5 y (r = 38-85). The ORR was 9%, 20%, 29% and 24% respectively. The cumulative ORR was 20.6%. The median time to first response was 1.4 months (M) while the median duration of response was 6.6 M. The most common AEs were nausea (33%), fatigue (30%), diarrhea (26%) and cough (24%). In a phase Ib trial, 57 pts with RRMM were stratified into 5 groups. ISA [3 mg/kg (Q2W); 5 mg/kg (Q2W); 10 mg/kg (Q2W); 10 mg/kg (QW-Q2W); 20 mg/kg (QW-Q2W)] in combination with lenalidomide (R) (25mg), and dexamethasone (D) (40 mg) was given. The median age of pts was 61 y (r = 42-76). The median time since the initial diagnosis was 4 y. The ORR was 33%, 67%, 63%, 50%, and 50% respectively. The cumulative ORR was 56% with complete response (CR) in 3.8 % pts, very good partial response (VGPR) in 32.7 % pts and PR in 19.2 % pts. The progression-free survival (PFS) was 8.5 M (r=4.73-16.59). The most common grade 3 and 4 AEs were neutropenia (60%), lymphopenia (58%), leukopenia (53%), anemia (25%), thrombocytopenia (38%), pneumonia (9%), fatigue (7%), and dyspnea (4%). In another phase Ib trial, 36 pts with RRMM were stratified into 3 groups. ISA (5 mg/kg; 10 mg/kg, 20 mg/kg) in combination with pomalidomide (P) (4 mg), and D (40 mg) was given. The ORR was 63%, 55%, and 50% respectively. The cumulative ORR was 55.5%. The median time to first response was 4.1 weeks (W) while the median duration of response was 33.1 W. The most common grade 3 AEs were neutropenia (81%), lymphopenia (75%), and leukopenia (75%). In another phase Ib trial involving 10 pts with RRMM, ISA (10-20 mg/kg) in combination with carfilzomib (CFZ) (27 mg) was given. The median number of prior lines of therapy was 4.5 (2-8). The ORR was 80% with VGPR in 20% pts and PR in 60% pts. The most common grade 3 and 4 AEs were lymphopenia (64%), anemia (9%), and neutropenia (9%). In a phase Ib trial involving 15 pts with NDMM, ISA (10 mg) in combination with bortezomib (V) (1.3 mg/m2) and cyclophosphamide (CY) (300 mg/m2) was given. The median age of pts was 71 y (r= 68-80). The ORR was 87% with CR in 33% pts, VGPR in 27% pts, and PR in 27% pts. The median time to first response was 1.5 M while the median duration of response was 11 M. The most common grade 3 and 4 AEs were lymphopenia (50%), leucopenia (18%), neutropenia (8%), anemia (6%) and thrombocytopenia (6%).
Conclusion:
In RRMM pts, ISA as a single agent has shown weaker efficacy when compared to combination regimens i.e. ORR 21% vs. 58%. The best result was seen when ISA was used in combination with CFZ demonstrating an ORR of 80%. In NDMM pts, combination regimens have shown excellent efficacy with an ORR of 87%. Nausea and fatigue were the major AEs reported with the monotherapy while neutropenia, leucopenia, and lymphopenia were the major AEs reported with the combination regimens. Further studies involving a larger population are required to gather evidence in favor of the improved efficacy and to evaluate AEs.

Disclosures
No relevant conflicts of interest to declare.