In a phase II study reported in the Journal of Clinical Oncology, Barker et al found that induction treatment with vismodegib followed by concurrent treatment with vismodegib and curative-intent radiation therapy showed efficacy in patients with locally advanced unresectable basal cell carcinoma.
As noted by the investigators, vismodegib—a Hedgehog pathway inhibitor active in basal cell carcinoma—may act as a radiosensitizer in this setting.
Study Details
The study included 24 patients enrolled at the University of California, San Francisco, and Memorial Sloan Kettering Cancer Center between 2013 and 2018. Vismodegib was given as induction at 150 mg once daily for 12 to 14 weeks before radiotherapy and concurrently with radiotherapy for 7 weeks.
Radiotherapy was given via three-dimensional conformal or intensity-modulated techniques at 66 to 70 Gy in 33 to 35 fractions over 6.6 to 7 weeks to targets with clinically or radiographically evident disease identified before induction therapy with vismodegib. Adjacent or draining regions at risk for subclinical disease were treated with 50 Gy in 25 fractions over 5 consecutive weeks.
The primary endpoint was locoregional control rate at 1 year after the end of treatment. The endpoint was considered met if the rate were at least 80%.
Key Findings
Median follow-up was 5.7 years (range = 0.6–9.3 years). Among 23 evaluable patients, 21 (91%, 95% confidence interval [CI] = 68%–98%) had locoregional tumor control at 1 year.
Objective response was observed in 12 of 19 evaluable patients (63%, 95% CI = 38%–84%) after induction and in 15 of 18 evaluable patients (83%, 95% CI = 59%–96%) after concurrent treatment with vismodegib and radiotherapy. Among all 24 patients, progression-free survival and overall survival rates were 100% and 96% at 1 year and 78% and 83% at 5 years.
Assessment of patient-reported quality of life on the Skindex-16 scale showed clinically meaningful improvement (median = 10-point improvement) in all subscales. Improvement in emotions and functioning subscales lasted for more than 1 year.
The most common treatment-related adverse events of any grade were dysgeusia (83%), fatigue (75%), and myalgia (75%); the most common grade 3 events were oral mucositis (8%) and hyponatremia (8%). No grade 4 or 5 treatment-related events were observed. One patient died of a ruptured aortic aneurysm immediately after completing radiotherapy.
The investigators concluded: “In patients with [locally advanced unresectable basal cell carcinoma], the combination of vismodegib and [radiotherapy] yielded high rates of locoregional control and progression-free survival and durable improvements in [patient-reported quality of life].”
Sue S. Yom, MD, PhD, of the Department of Radiation Oncology, Department of Otolaryngology–Head and Neck Surgery, University of California San Francisco, is the corresponding author of the Journal of Clinical Oncology article.
Disclosure: The study was supported by the National Cancer Institute and Genentech. For full disclosures of the study authors, visit ascopubs.org.
