Basilea reports derazantinib/PD-L1 checkpoint inhibitor combination results from dose-finding part of FIDES-02 study in patients with solid tumors at ASCO GU symposium

Basel, Switzerland, February 12, 2021

Basilea Pharmaceutica Ltd. (SIX: BSLN) announced today that data on the safety, tolerability and preliminary efficacy of the fibroblast growth factor receptor (FGFR) inhibitor derazantinib in combination with the PD-L1 checkpoint inhibitor atezolizumab, in patients with advanced solid tumors from the phase 1b dose-finding cohort in the FIDES-02 study, were presented at the virtual American Society of Clinical Oncology Genitourinary Cancers Symposium (ASCO GU 2021), held from February 11 to 13, 2021.¹

The derazantinib-atezolizumab combination was well tolerated and no dose-limiting toxicities were observed. The most commonly reported adverse events were fatigue/asthenia (weakness), nausea and diarrhea. The study demonstrated that derazantinib and atezolizumab can be safely combined at doses of 300 mg of daily oral derazantinib, which is the derazantinib monotherapy dose used in the phase 2 study FIDES-01, and 1200 mg atezolizumab, administered intravenously once every three weeks which was the maximum dose pre-specified in the protocol.²

Several patients are still receiving treatment with derazantinib and atezolizumab, including one patient with a bile duct cancer and FGFR2 gene fusion, who is ongoing in the study for more than nine months and was reported with a partial response with continued tumor shrinkage. The combination of derazantinib and atezolizumab is supported by preclinical data demonstrating derazantinib’s strong inhibition of colony-stimulating-factor-1-receptor kinase (CSF1R). CSF1R inhibition may revert tumor-induced immunosuppression and thereby enhance the response to immune-checkpoint inhibition.

Dr. Marc Engelhardt, Chief Medical Officer, said: “The recently announced clinical proof of concept for derazantinib as monotherapy in the FIDES-01 study in patients with FGFR2 gene fusion-positive intrahepatic cholangiocarcinoma and the efficacy signal obtained in the group of patients with advanced solid tumors in the FIDES-02 study are encouraging. Considering the manageable safety and tolerability profile and the rapidly evolving treatment landscape in urothelial cancer in patients both with and without FGFR genetic aberrations, we additionally plan to amend the FIDES-02 study protocol to explore a higher dose of derazantinib in two cohorts of this study. These cohorts would explore whether dosing derazantinib at its previously established maximum tolerated daily dose, which is about 30% higher than the current phase 2 dose, may provide additional benefits in monotherapy and combination to patients with FGFR-positive urothelial cancer.“