Results from a Phase II Study of Isatuximab As a Single Agent and in Combination with Dexamethasone in Patients with Relapsed/Refractory Multiple Myeloma

Background: Isatuximab (ISA) targets CD38-expressing tumor cells through a combination of activities, including antibody-dependent cellular cytotoxicity, direct pro-apoptotic activity, and complement-dependent cytotoxicity. A phase I study evaluating ISA monotherapy demonstrated promising clinical a...

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Published in:Blood 2018-11, Vol.132 (Supplement 1), p.155-155
Main Authors: Dimopoulos, Meletios A, Bringhen, Sara, Anttila, Pekka, Capra, Marcelo, Cavo, Michele, Cole, Craig E., Gasparetto, Cristina J, Hungria, Vania T.M., Jenner, Matthew, Vorobyev, Vladimir, Yanez Ruiz, Eduardo, Yin, Jianyun, Hamlett, Anthony, Vij, Ravi
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Language:English
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Summary:Background: Isatuximab (ISA) targets CD38-expressing tumor cells through a combination of activities, including antibody-dependent cellular cytotoxicity, direct pro-apoptotic activity, and complement-dependent cytotoxicity. A phase I study evaluating ISA monotherapy demonstrated promising clinical activity in 35 patients with relapsed/refractory multiple myeloma (RRMM) (Martin T et al, J Clin Oncol 2014; 32:8532). This is an ongoing phase II study (NCT01084252) with 2 stages: stage 1 to select the dose for stage 2 of the study, and stage 2 to assess efficacy and safety of ISA monotherapy or in combination with dexamethasone in RRMM. In stage 1, patients were randomized to 1 of 3 dose groups: ISA 3 mg/kg Q2W, 10 mg/kg Q2W × 2 cycles then Q4W, or 10 mg/kg Q2W. Based on pharmacokinetic data, a fourth dose of 20 mg/kg QW × 4 doses then Q2W was added. The overall response rates (ORRs) for the 4 dosing schemes were 4% (1/23), 20% (5/25), 29% (7/24), and 24% (6/25), respectively. Based on these results, a dose of 20 mg/kg QW for cycle 1 followed by 20 mg/kg Q2W in subsequent cycles was chosen for stage 2 of the study (Richter J et al, J Clin Oncol 2016;34:8005). Here, we report the baseline characteristics and demographic data from stage 2 at the selected dosing scheme from stage 1. Full safety and efficacy data will be presented at the meeting. Methods: This study enrolled patients with MM who had previously received an immunomodulatory drug and a proteasome inhibitor. Patients received ISA monotherapy (20 mg/kg on Day 1, 8, 15, and 22 [QW] of cycle 1 followed by 20 mg/kg on Day 1 and 15 [Q2W] of subsequent cycles) or ISA in combination with dexamethasone (40 mg/day [20 mg/day in patients ≥75 years old]). The primary objective was to evaluate the activity of ISA as monotherapy and in combination with dexamethasone in patients with RRMM in terms of ORR. Results: A total of 165 patients received at least 1 cycle of treatment. Median age was 67 (37-85) years. Median time from diagnosis to first dose was 5.35 (0.7-23.0) years. Median number of prior lines was 4 (2-11) and median number of prior regimens was 6 (2-17). Patients received a median of 5 (1-17) cycles of treatment, with a median duration of exposure of 22 (1-69) weeks. Discontinuation occurred in 106 (64.2%) patients due to adverse events (15 patients, 9.1%), disease progression (85 patients, 51.5%), or patient decision (6 patients, 3.6%). Conclusion: The full efficacy and safety data for this heavily pre
ISSN:0006-4971
1528-0020
DOI:10.1182/blood-2018-155