Why Hedgehog Inhibitors Are Not Interchangeable in Advanced BCC

By Sophie Lindqvist

The phase II randomized, double-blind BOLT analysis reported a 56% objective response rate with oral sonidegib (Odomzo; Sun Pharma) 200 mg once daily in locally advanced basal cell carcinoma (laBCC), versus 8% in metastatic disease.

In pivotal ERIVANCE, vismodegib (Erivedge; Genentech) achieved an investigator-assessed response rate of 60.3% in laBCC and a median duration of response of 26.2 months. International, open-label STEVIE reported 68.5% response in laBCC, while 98% of patients had at least one treatment-emergent adverse event.

Those figures do not establish interchangeability. No head-to-head trial has compared the drugs, and the studies used different response definitions. Gaurav Singh, MD, MPH, a dermatologist and Mohs surgeon at City of Hope Comprehensive Cancer Center in Chicago, made that distinction while leading a Dermatology Times Case-Based Peer Perspectives custom video series on three recurrent cases.

Advanced disease extends beyond tumor size

Singh sets the size threshold above 2 cm, and above 4 cm under some standards, but treats location as decisive. A 3-cm lesion on the back may not qualify, whereas a 5-mm lesion on the eyelid margin could.

Because BCC lacks a uniform staging system, he borrows risk factors from American Joint Committee on Cancer systems used for other cancers:

• Invasion beyond subcutaneous fat.
• Morpheaform or micronodular histology.
• Recurrence or a scarred site.
• Prior radiation.
• A history of leukemia, lymphoma, or transplant.

The pathology report may understate risk; Singh said roughly one-third of superficial BCCs get upstaged on final pathology.

Patient preference also drives his decision to introduce systemic therapy. “Hedgehog inhibitors are likely underutilized, and systemic therapy should be considered earlier than it currently is for a lot of patients,” Singh said.

Singh often starts a Hedgehog pathway inhibitor before surgery despite the label, aiming for a smaller defect and scar. He also sees potential benefit for a smaller tumor at a cosmetically sensitive site, or for a patient with repeated surgery and prior radiation. In multidisciplinary care, he combines oral therapy with surgery and adjuvant radiation when indicated.

Pharmacokinetics separate the agents

Both drugs are oral and dosed once daily, but their exposure profiles differ sharply:

• Sonidegib: 200 mg; half-life of about 1 month; volume of distribution above 9,000 L; up to 4 months to reach steady state.
• Vismodegib: 150 mg; half-life of 4 to 12 days; volume of distribution near 30 L; about 3 weeks to reach steady state.

Singh’s practical explanation is anatomical: sonidegib’s high distribution carries it to the skin, where the BCC sits, and its long half-life keeps it there. Vismodegib clears much faster and reaches steady state sooner.

Trial percentages are not interchangeable rankings

BOLT required a reduction of more than 50% in the bidimensional sum for partial response; the other trial in Singh’s comparison required a 30% reduction in one dimension. Applying RECIST-like criteria to sonidegib would put its complete response rate near 21%, he said.

His clinical argument goes beyond axis-based scoring. Tumors grow in three dimensions, Singh noted, and changes in at least two dimensions, including length and width, can materially affect surgical morbidity.

A 2026 claims analysis found that sonidegib-treated patients stayed on therapy longer and were 33% less likely to have gastrointestinal conditions, 71% less likely to have taste or smell conditions, and 52% less likely to have muscle spasms than vismodegib-treated patients. “I do not consider sonidegib and vismodegib to be interchangeable in clinical practice,” Singh said.

He uses sonidegib first for laBCC. In metastatic disease, he usually moves to a PD-1 inhibitor such as cemiplimab (Libtayo; Regeneron Pharmaceuticals) after Hedgehog inhibitor failure rather than switching within the class.

What does this change for recurrent locally advanced BCC?

It changes timing more than the drug list. Singh supports earlier systemic consideration, especially after prior surgery or radiation, and pairs systemic treatment with planned reassessment.

His laboratory schedule checks creatine kinase, creatinine, complete blood count, and comprehensive metabolic panel at baseline, weekly for 2 months, then every 4 weeks.

Adverse effects have a recognizable timetable in his practice:

• Fatigue, muscle spasms, nausea, and dysgeusia typically emerge before month 4.
• Alopecia appears around month 5.
• Weight loss follows after month 6.

For muscle spasms, he gives L-carnitine 400 mg three times daily. For alopecia, he uses oral minoxidil, finasteride, or spironolactone. He keeps the trial dosing schedule and permits drug holidays of up to 21 days, but does not alter the dose.

Response usually appears around month 4. If he sees no response by month 6, he typically changes classes, often to a PD-1 inhibitor, and expects tumor reduction in two dimensions. Singh urges colleagues to broaden referral for patients with prior surgery and radiation.

Looking ahead, Singh’s model favors earlier multidisciplinary care, planned reassessment at four to six months, and agent-specific safety monitoring rather than treating the two Hedgehog pathway inhibitors as substitutes.