Hepatotoxicity as dose-limiting toxicity of the combination of bosutinib and atezolizumab in patients with chronic myeloid leukemia. Results of the ZEROLMC study.

In the field of chronic myeloid leukemia (CML), new strategies are needed to increase the rate of successful treatment discontinuations, a crucial goal in this disease. Anti-PD-L1 checkpoint inhibitors are a promising therapeutic approach in CML after the demonstration of an increase of these inhibitory molecules in patients with CML. A phase Ib/II (NCT04793399, registration date March 11, 2021) open-label exploratory trial has been conducted to evaluate the safety of atezolizumab, a humanized anti-PD-L1 antibody, in combination with bosutinib in patients with newly diagnosed chronic phase CML. A total of 36 patients were planned to be enrolled, but the study had to be prematurely terminated due to safety concerns. Nine patients were included in the study, and only 8 went on to receive the combination with atezolizumab. There were a total of 44 adverse events (AEs) during the study period. The most frequent were gastrointestinal (50%), mostly mild (86% grade 1-2). The most serious AEs were hepatic. There were 17 hepatic AEs in 5 patients. Of the hepatic AEs 5 were during the bosutinib monotherapy phase and 12 during the combination phase (AST increase x4, ALT increase x4, blood bilirubin increase x1, alkaline phosphatase elevation x2, GGT increase x2), most of them grade 3-4. There were 2 patients who presented a dose-limiting toxicity; a grade 3 elevation of transaminases, that led to premature termination of the study. The combination of atezolizumab with bosutinib presents hepatotoxicity as a dose-limiting effect and therefore we do not recommend to explore this combination in future studies.

ROP-ET: a prospective phase III trial investigating the efficacy and safety of ropeginterferon alfa-2b in essential thrombocythemia patients with limited treatment options.

Interferon-based therapies, such as ropeginterferon alfa-2b have emerged as promising disease-modifying agents for myeloproliferative neoplasms (MPNs), including essential thrombocythemia (ET). Current ET treatments aim to normalize hematological parameters and reduce the thrombotic risk, but they do not modify the natural history of the disease and hence, have no impact on disease progression. Ropeginterferon alfa-2b (trade name BESREMi®), a novel, monopegylated interferon alfa-2b with an extended administration interval, has demonstrated a robust and sustained efficacy in polycythemia vera (PV) patients. Given the similarities in disease pathophysiology and treatment goals, ropeginterferon alfa-2b holds promise as a treatment option for ET. The ROP-ET trial is a prospective, multicenter, single-arm phase III study that includes patients with ET who are intolerant or resistant to, and/or are ineligible for current therapies, such as hydroxyurea (HU), anagrelide (ANA), busulfan (BUS) and pipobroman, leaving these patients with limited treatment options. The primary endpoint is a composite response of hematologic parameters and disease-related symptoms, according to modified European LeukemiaNet (ELN) criteria. Secondary endpoints include improvements in symptoms and quality of life, molecular response and the safety profile of ropeginterferon alfa-2b. Over a 3-year period the trial assesses longer term outcomes, particularly the effects on allele burden and clinical outcomes, such as disease-related symptoms, vascular events and disease progression. No prospective clinical trial data exist for ropeginterferon alfa-2b in the planned ET study population and this study will provide new findings that may contribute to advancing the treatment landscape for ET patients with limited alternatives. TRIAL REGISTRATION: EU Clinical Trials Register; EudraCT, 2023-505160-12-00; Registered on October 30, 2023.