in a successful effort to maintain efficacy while reducing treatment discontinuation caused by unacceptable side effects, Vishal Patel, MD, said at Innovations in Dermatology: Virtual Spring Conference 2021.
“It’s the tolerability issues that make these drugs very difficult to prescribe and use regularly. What we’ve seen in the last few years is that a lot of alternative dosing regimens have been published that have been both effective at treating the tumor and keeping the tumor clear and at bay while lowering the side-effect profile,” explained Dr. Patel, a Mohs surgeon and director of the cutaneous oncology program at the George Washington University Cancer Center in Washington, D.C.
Product labeling for the two available hedgehog pathway inhibitors, vismodegib (Erivedge) and sonidegib (Odomzo), calls for once-daily therapy until disease progression or unacceptable toxicity. Studies show that, when used in this way, these agents achieve objective response rates in the 40% range for patients with locally advanced BCC and 15%-33% for those with metastatic BCC.
“The critical thing in these patients is not that the drugs work – although they can work in quite remarkable ways – but rather it’s that nearly all patients experience at least one side effect. And grade 3 or 4 adverse effects that can lead to cessation of drug occur in about 25% of patients,” he said at the conference sponsored by MedscapeLIVE! and the producers of the Hawaii Dermatology Seminar and Caribbean Dermatology Symposium.
The classic side effects of the hedgehog pathway inhibitors are muscle spasms, hair loss, fatigue, loss of taste, diarrhea, and weight loss.
Among the alternative dosing regimens that have been published with good results, mostly in single-center retrospective case series, are a weekdays-on/weekends-off strategy at the Cleveland Clinic and an Italian approach entailing an initial 3-4 months of daily therapy followed by a switch to alternate-day therapy.
But Dr. Patel favors a different off-label regimen in lieu of Food and Drug Administration–recommended daily dosing indefinitely. It takes advantage of the fact that most patients don’t begin to get the classic side effects until about the 3-month mark.
“What we’ve begun to recommend as a much better option for patients who need to be on the drug potentially forever is that the drug is dosed daily for 3 months to shrink the tumor and get the optimal effect, and then at that point we taper the dose down to every other day, then every third day, or even up to a week as long as the tumor continues to stay at bay. If there’s any sign of recurrence or a scouting biopsy shows tumor, we reinstitute the daily medicine,” the dermatologist said.
This strategy requires careful monitoring for emergence of the typical side effects. Also, an important caveat regarding sonidegib is that it shouldn’t be given concomitantly with medications that are moderate or strong inhibitors of CYP3A, so it’s essential to get a complete medical history when giving this drug, Dr. Patel noted.
He reported having no financial conflicts regarding his presentation.
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