A Phase 2 Multi-Center, Open Label Study of Isatuximab Added to Standard Cybord Induction and Lenalidomide Maintenance Treatments in Newly Diagnosed, Transplant Eligible Multiple Myeloma

Background: Despite recent improvements, myeloma is still incurable. There is need to add new therapeutic tools. For young and fit patients, the current standard first-line therapy is a proteasome inhibitor (PI) containing induction, followed by stem cell collection, high dose Melphalan and autologous stem cell transplantation, followed by maintenance lenalidomide therapy in Canada. The anti-CD38 antibodies showed interesting activity in myeloma, and significant synergism with PI and IMiD based regimens. This CMRG-008 trial is designed to explore the benefit of adding Isatuximab to the current Canadian standard of care (CyBorD induction/Autologous SCT/Maintenance Len) in a single arm phase II trial.

Design and Methods: Phase II study. Transplant eligible newly diagnosed myeloma patients (TE-NDMM) will receive Isatuximab added to four cycles of standard induction CyBorD chemotherapy (Cyclophosphamide 300 mg/m ² PO, Bortezomib 1.5 mg/m ² SC, and Dex 40 mg PO, all given on days 1, 8, 15 and 22 of 28-day cycles; Isatuximab 10 mg/kg IV days 1, 8, 15 and 22 of cycle 1; days 1 and 15 of cycles 2-4). After the completion of the induction treatment, subjects achieving at least stable disease will receive stem cell mobilization, collection of hematopoietic stem cells, high dose melphalan chemotherapy, and autologous stem cell transplantation. Maintenance treatment will start at 100 days (+/- 7 days) after the transplantation date (and to be continued until disease progression). The maintenance treatment will consist of Isatuximab administered in combination with Lenalidomide in 28-day cycles (Lenalidomide: 10 mg daily on days 1-21 of every cycle; Isatuximab: 10 mg/kg IV on days days 1, 8, 15 and 22 of cycle 1; days 1 & 15 of cycles 2-3; then day 1 of each subsequent cycle).

The objectives: To evaluate the benefit of adding Isatuximab to CyBorD (induction = Isa + CyBorD) and Lenalidomide (maintenance = Isa + Lenalidomide) in transplant-eligible myeloma patients.

Primary Endpoint: To determine the response rate (VGPR or better) defined by IMWG criteria at 100 days (+/- 7 days) after the autologous stem cell transplant (ASCT).

Secondary Endpoints: A) To determine the response rate (VGPR or better) after induction treatment (before ASCT), and at 12 months, 24 months and 36 months. B) To evaluate additional efficacy outcomes including progression free survival (PFS), and overall survival (OS), time to response and duration of response. C) To confirm the feasibility, safety and tolerability of adding Isatuximab to CyBorD and to maintenance lenalidomide in transplant-eligible newly diagnosed myeloma patients. D) To determine the feasibility of autologous stem cell collection after Isa + CyBorD induction treatment.

The key inclusion criteria are having a TE-NDMM with a measurable disease; adequate performance status; and adequate organ functions.

The key exclusion criteria include previous exposure to anti-CD38 therapy, intolerance to CyBorD, adverse cardiac history, pulmonary disease, central nervous system disease, congenital or acquired immune suppression, and other concurrent severe or uncontrolled medical conditions.

Statistics and Sample Size: Considering that the response rate (VGPR or better) after CyBorD induction therapy, high dose chemotherapy and autologous SCT is about 70-78%; and assuming a response rate (VGPR or better) to Isa-CyBorD induction and autologous stem cell transplant at 100 +/- 7 days of 88%; a sample size of 65 evaluable subjects will allow estimating the 95% confidence interval with a precision of +/- 7.9%. For the assumed rate and sample size, the lower bound of the confidence interval will be estimated to be larger than 80%. Assuming a 10% drop out rate, a total study size of 72 patients will be considered.

This study is expected to open to recruitment in the third quarter of 2021.

Clinicaltrials.gov #: NCT04786028.