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.

Abstract PD1-02: Withdrawn

This abstract was withdrawn by the authors.

Citation Format: Cortes J, Martin M, Pernas S, Gomez Pardo P, Lopez-Tarruella S, Gil-Martin M, Manso L, Ciruelos E, Perez-Fidalgo JA, Hernando C, Ademuyiwa FO, Weilbaecher K, Mayer I, Pluard TJ, Martinez Garcia M, Vahdat L, Wach A, Barker D, Romagnoli B, Kaufman PA. Withdrawn [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr PD1-02.

SEOM guidelines for cervical cancer

Cervical cancer (CC) is the second most common cancer worldwide, strongly linked to high-risk human papilloma virus infection. Although screening programs have led to a relevant reduction in the incidence and mortality due to CC in developed countries, it is still an important cause of mortality in undeveloped countries. Clinical stage is still the most relevant prognostic factor. In early stages, the primary treatment is surgery or radiotherapy, whereas concomitant chemo-radiotherapy is the conventional approach in locally advanced stages. In the setting of recurrent or metastatic CC, for the first time ever, the combination of chemotherapy plus bevacizumab prolongs the overall survival beyond 12 months. Therefore, this regimen is considered by most of the oncologist a new standard of care for metastatic/recurrent CC.

Abstract P6-11-08: A multicenter, open-label Ph IB/II study of BEZ235, an oral dual PI3K/mTOR inhibitor, in combination with paclitaxel in patients with HER2-negative, locally advanced or metastatic breast cancer

Background: The PI3K/AKT/mTOR pathway is frequently altered in breast cancer (BC). Alterations in PIK3CA or inactivation of PTEN are observed in 10–40% and in up to 50% of breast tumors, respectively. The PI3K/AKT/mTOR pathway can be further activated through various receptor classes or cross-talk with other pathways, making it a rational target for therapeutic intervention in BC. BEZ235 is an oral dual inhibitor of mTOR and PI3K. It has demonstrated anti-proliferative activity, substantial growth inhibition, and induction of apoptosis in preclinical studies. In a Ph I study, single-agent BEZ235 (600 mg BID) was shown to have less toxicity than the equivalent once-daily dosing, and have preliminary evidence of activity in advanced solid tumors (Arkenau, et al. ASCO 2012:#3097).

Methods: This is a multicenter, open-label Ph IB/II study of continuous, oral BEZ235 twice daily (BID) in combination with paclitaxel (80 mg/m2; IV weekly [QW]) in women with HER2-negative (HER2–), metastatic or inoperable locally advanced BC (NCT01495247).

For the Ph IB part, women with HER2–, metastatic or inoperable locally advanced BC, who are suitable for treatment with paclitaxel, are eligible for enrollment. The primary objective is to determine the maximum tolerated dose (MTD)/recommended Ph II dose (RP2D) of BEZ235 in combination with paclitaxel based on dose-limiting toxicities (DLTs) using an adaptive 5-parameter Bayesian logistic regression model with overdose control. The MTD is defined as the highest drug dosage not causing medically unacceptable DLTs in more than 35% of the treated patients during Cycle 1 (1 cycle = 28 days). Secondary objectives include safety (CTCAE), preliminary activity (RECIST), and pharmacokinetics (PK). Estimated enrollment is 15–30 patients into the Ph IB part.

Results: As of June 2012, 13 pts have been enrolled into the Ph IB part of the trial. The first cohort (n = 7 pts) received BEZ235 200 mg BID + 80 mg/m2 QW paclitaxel. Of these 7 pts, 3 are ongoing, with 2 pts having received treatment for more than 12 weeks so far, and 4 pts have discontinued (2 due to an adverse event [AE]; 1 due to an AE/pt's decision; and 1 due to disease progression). Of the 6 evaluable pts in the first cohort, 2 experienced DLTs: Grade 3 stomatitis (1 pt) and Grade 2/3 neutropenia (1 pt). Most common AEs included stomatitis and GI toxicity (e.g. diarrhea, nausea/vomiting). To date, reported Grade 3 AEs related to study drug were stomatitis (2 pts), neutropenia (1 pt), and skin rash (1 pt). Among the 3 pts with at least one tumor evaluation, 1 pt with a triple-negative metastatic BC, who had previously been treated with paclitaxel, experienced a RECIST partial response which was confirmed on second tumor evaluation. PK analysis is ongoing.

Conclusions: Additional patients have been enrolled at BEZ235 200 mg BID/paclitaxel 80 mg/m2 QW to provide further information on the safety and activity profile of this combination. Updated safety and efficacy results will be presented. Upon determination of the MTD/RP2D, the randomized Ph II part will begin to compare weekly paclitaxel given with or without BEZ235 BID as the first-line treatment of HER2– metastatic BC.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P6-11-08.