Interim analysis of the multinational, post-authorization safety study (NISSO) to assess the long-term safety of sonidegib in patients with locally advanced basal cell carcinoma

Following the pivotal phase II trial BOLT, the Hedgehog (Hh) inhibitor sonidegib was approved in the EU to treat locally advanced basal cell carcinoma (laBCC) in patients not amenable to surgery or radiotherapy. We report safety data from the interim analysis of the real-world NISSO study. NISSO is an ongoing non-interventional, multinational, post-authorization safety study (NCT04066504). Patients with laBCC are treated with sonidegib 200 mg orally once daily and followed for 3 years. Dose modifications were allowed according to the local prescribing information. Between May 6, 2019, and March 15, 2022, 321 patients with laBCC were enrolled at 46 European sites (data cut-off: June 22, 2023). Treatment was discontinued in 241 (75.1%) patients, with the main reasons being the patient/guardian decision (n = 69, 28.6%), treatment success (n = 40, 16.6%) and the physician decision (n = 35, 14.5%). The median duration of sonidegib exposure was 8.8 months (4.4-13.7 months). Overall, 284 (88.5%) patients had ≥ one treatment-emergent adverse event (TEAE). Most TEAEs were ≤ grade 2 and the most common were muscle spasms (n = 141; 43.9%), dysgeusia (n = 119; 37.1%), and alopecia (n = 97; 30.2%). After 3 months of treatment, the cumulative rates of muscle spasms, dysgeusia, and alopecia were 21.8%, 16.2%, and 3.7%, respectively. TEAEs led to treatment discontinuation in 59 (18.4%) patients, while 149 (46.4%) patients had at least one TEAE leading to dose reduction or interruption. Serious drug-related TEAEs were reported in 13 (4.1%) patients. These results confirm the safety profile previously observed. Most patients experienced the onset of common TEAEs after 3 months of treatment, and the cumulative incidence of most common TEAEs was 10-20% lower compared to the BOLT study, except for dysgeusia and fatigue that had a similar incidence. The percentage of patients experiencing TEAEs requiring interruption or dose reduction was similar to the BOLT study, while the proportion of patients with TEAE leading to discontinuation of sonidegib was lower. This study demonstrates that the tolerability of sonidegib is manageable in routine clinical practice. NCT04066504.