Isatuximab plus atezolizumab in patients with advanced solid tumors: results from a phase I/II, open-label, multicenter study

M. Simonelli, E. Garralda, F. Eskens, M. Gil-Martin, C. J. Yen, R. Obermannova, Y. Chao, S. Lonardi, B. Melichar, V. Moreno, M. L. Yu, A. Bongiovanni, E. Calvo, S. Rottey, J. P. Machiels, A. Gonzalez-Martin, L. Paz-Ares, C. L. Chang, W. Mason, C. C. LinD. A. Reardon, M. Vieito, A. Santoro, R. Meng, G. Abbadessa, F. Menas, H. Lee, Q. Liu, C. Combeau, N. Ternes, S. Ziti-Ljajic, C. Massard

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    Abstract

    Background: The anti-CD38 antibody isatuximab is approved for the treatment of relapsed/refractory multiple myeloma, but there are no data on its efficacy in solid tumors. This phase I/II study (NCT03637764) assessed the safety and activity of isatuximab plus atezolizumab (Isa + Atezo), an anti-programmed death-ligand 1 (PD-L1) antibody, in patients with immunotherapy-naive solid tumors: epithelial ovarian cancer (EOC), glioblastoma (GBM), hepatocellular carcinoma (HCC), and squamous cell carcinoma of the head and neck (SCCHN). Patients and methods: Phase I assessed safety, tolerability, pharmacokinetics, pharmacodynamics, and the recommended phase II dose (RP2D) of isatuximab 10 mg/kg intravenously (i.v.) every week for 3 weeks followed by once every 3 weeks + atezolizumab 1200 mg i.v. every 3 weeks. Phase II used a Simon's two-stage design to assess the overall response rate or progression-free survival rate at 6 months (GBM cohort). Interim analysis was carried out at 6 months following first dose of the last enrolled patient in each cohort. Pharmacodynamic biomarkers were tested for CD38, PD-L1, tumor-infiltrating immune cells, and FOXP3+ regulatory T cells (Tregs) in the tumor microenvironment (TME). Results: Overall, 107 patients were treated (EOC, n = 18; GBM, n = 33; HCC, n = 27; SCCHN, n = 29). In phase I, Isa + Atezo showed an acceptable safety profile, no dose-limiting toxicities were observed, and RP2D was confirmed. Most patients experienced ≥1 treatment-emergent adverse event (TEAE), with ≤48.5% being grade ≥3. The most frequent TEAE was infusion reactions. The study did not continue to stage 2 based on prespecified targets. Tumor-infiltrating CD38+ immune cells were reduced and almost cleared after treatment. Isa + Atezo did not significantly modulate Tregs or PD-L1 expression in the TME. Conclusions: Isa + Atezo had acceptable safety and tolerability. Clinical pharmacodynamic evaluation revealed efficient target engagement of isatuximab via treatment-mediated reduction of CD38+ immune cells in the TME. Based on clinical data, CD38 inhibition does not improve responsiveness to PD-L1 blockade in these patients.

    Original languageEnglish
    Article number100562
    JournalESMO Open
    Volume7
    Issue number5
    DOIs
    Publication statusPublished - 1 Oct 2022

    Keywords

    • anti-CD38
    • anti-PD-L1
    • atezolizumab
    • isatuximab
    • solid tumors

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