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

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.

Phase I dose-escalation study of aflibercept in combination with docetaxel and cisplatin in patients with advanced solid tumours.

BACKGROUND: This phase I cohort study investigated aflibercept (vascular endothelial growth factor (VEGF) trap) plus docetaxel and cisplatin in patients with advanced solid tumours. METHODS: Patients received intravenous aflibercept 4, 5, or 6 mg kg(-1) with docetaxel and cisplatin (75 mg m(-2) each) on day 1 of a 3-week cycle until progressive disease or unacceptable toxicity. Primary objectives were determining cycle 1 dose-limiting toxicities (DLTs) and the aflibercept recommended phase II trial dose (RP2D) for this combination. RESULTS: During the dose-escalation phase (n=16), there were two DLTs of febrile neutropenia (at 4 and 5 mg kg(-1)). Granulocyte colony-stimulating factor prophylaxis was subsequently recommended. The RP2D of aflibercept was established at 6 mg kg(-1) and administered to 14 additional patients. The most frequent grade 3/4 adverse events (AEs) were neutropenia (43.3%), stomatitis (20.0%), asthenia/fatigue (20.0%), and hypertension (16.7%). All-grade AEs associated with VEGF blockade included epistaxis (83.3%), dysphonia (70.0%), proteinuria (53.3%), and hypertension (50.0%). There were five partial responses (16.7%) and 18 cases of stable disease (60.0%) (lasting >3 months in 10 patients). There were no pharmacokinetic (PK) interactions between the three drugs. CONCLUSION: Aflibercept 6 mg kg(-1) with docetaxel and cisplatin 75 mg m(-2) every 3 weeks is the RP2D based on tolerability, antitumour activity, and PKs.