WAIKOLOA, HAWAII – The familiar oral triazole antifungal agent itraconazole (Sporanox) is under active investigation for an unexpected use: as adjunctive therapy in patients with locally advanced or metastatic basal cell carcinoma.
“The promise of this drug is that the use of itraconazole with vismodegib or sonidegib may actually enhance the effectiveness of those drugs and also reduce the frequency of grade 2 toxicities by perhaps allowing a lower dose of vismodegib or sonidegib,” Dr. David L. Swanson said at the Hawaii Dermatology Seminar provided by the Global Academy for Medical Education/Skin Disease Education Foundation.
Dr. David L. Swanson
“Be looking for this drug that we use to treat toenail fungus as a potential drug for locally advanced or metastatic basal cell carcinoma,” advised Dr. Swanson, a dermatologist at the Mayo Clinic in Scottsdale, Ariz.
Vismodegib (Erivedge) has been a game changer for patients with inoperable locally advanced or metastatic breast cancer. “The response to this drug was amazing,” Dr. Swanson said of the landmark study which led to its approval in 2012 (N Engl J Med. 2012; 366[23]:2171-9).
Sonidegib (Odomzo), which like vismodegib inhibits the essential Hedgehog signaling pathway component known as Smoothened, was approved by the Food and Drug Administration in 2015 as the second oral drug in this novel class.
While the clinical benefits of these two drugs in patients with the most horrific basal cell carcinomas are extremely impressive, vismodegib and sonidegib have two major drawbacks: The tumors eventually develop resistance and commence growing again, and onerous grade 2 side effects requiring dose reduction are extremely common. The most frequent of these limiting side effects are a disturbed sense of taste, muscle spasms, alopecia, and weight loss.
The hope is that itraconazole may be of help with both issues, according to Dr. Swanson. It turns out that the antifungal agent is also an inhibitor of the Hedgehog pathway, and via a different mechanism than that of vismodegib and sonidegib.
He pointed to an international open-label exploratory phase II study led by Dr. Jean Y. Tang of Stanford (Calif.) University. The investigators treated 19 patients with a total of 90 basal cell carcinomas with oral itraconazole at 200 mg twice a day for 1 month or 100 mg twice a day for an average of 2.3 months.
The treatment reduced Hedgehog signaling pathway activity by 65%, Ki67 tumor cell proliferation by 45%, and tumor area by 24% (J Clin Oncol. 2014 Mar 10;32[8]:745-51).
These results aren’t as dramatic as what’s achieved using vismodegib or sonidegib. As stand-alone therapy, itraconazole doesn’t compare with those agents. However, the hope is that when itraconazole is prescribed in conjunction with vismodegib or sonidegib it will permit the latter drugs to be used at lower doses with no drop-off in efficacy, which would mean less grade 2 toxicity. Moreover, since itraconazole inhibits Hedgehog signaling through a mechanism that is different from that of the more potent agents, combination therapy might delay onset of tumor resistance, Dr. Swanson explained.
He reported having no financial conflicts of interest regarding his presentation.
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