The next dramatic advance in the treatment of melanoma may arise from highly promising clinical trials in which immune checkpoint inhibitors and anti-BRAF/MEK agents are being pushed forward in the treatment paradigm and utilized as neoadjuvant therapy in patients with stage III resectable disease, John M. Kirkwood, MD, predicted at a virtual forum on cutaneous malignancies jointly presented by the Postgraduate Institute for Medicine and Global Academy for Medical Education.

John Kirkwood, MD, professor of medicine, dermatology, and translational science at the University of Pittsburgh

Dr. John M. Kirkwood

These agents have already demonstrated profound efficacy, first in stage IV metastatic disease and more recently as adjuvant therapy for resected stage III melanoma. Now, there is a great interest in learning whether by prescribing them preoperatively, patients might reduce their risk of advancing to metastatic disease. And neoadjuvant therapy offers an extremely attractive feature: It yields results in an accelerated fashion.

“The major problem with postoperative adjuvant trials in melanoma since 1984 is the long time to maturity. Many of us don’t want to wait the full 9 or 10 years for a full-bore, phase 3 adjuvant trial in stage III melanoma to mature,” explained Dr. Kirkwood, professor of medicine, dermatology, and translational science and coleader of the melanoma and skin cancer program at the University of Pittsburgh. “The opportunity to treat a patient who presents with a bulky lymph node, has a biopsy, and then can be treated for 3 or 6 weeks or sometimes even longer periods with a therapy that’s promising allows us to ask what’s going on in the tumor tissue, what’s going on in the clinical response at 3 or 6 weeks, and if there’s pathological complete or near-complete response under the microscope.”

Because pathological complete response is a strong predictor of relapse-free survival, this neoadjuvant-forward therapeutic strategy has the potential to provide patients and their physicians with an early forecast of likely clinical outcome only 4-6 weeks into treatment. Also, there is both preclinical and clinical evidence that neoadjuvant therapy may offer a survival advantage over adjuvant therapy, perhaps as a result of early treatment of micrometastatic disease. Another benefit of neoadjuvant therapy for melanoma is the resultant tumor shrinkage, which can permit less extensive surgery.

Dr. Kirkwood highlighted a phase 2 clinical trial conducted at the University of Pittsburgh to illustrate the potential of neoadjuvant therapy in melanoma. The ongoing single-arm study includes 32 patients with stage IIIB or IIIC resectable melanoma along with accessible tumor for biopsy and intratumoral injections of CMP-001, a toll-like receptor 9 agonist. According to the Eighth Edition of the American Joint Committee on Cancer staging manual, stage IIIB melanoma has a 10-year mortality of 23%, and stage IIIC disease has 40%.

CMP-001 triggers type 1 interferon production through activation of plasmacytoid dendritic cells. The resultant inflammatory response draws T cells into the tumor to enhance the response to immunotherapy, which in this study was nivolumab (Opdivo), a human programmed death ligand 1 (PD-L1)–blocking antibody. The neoadjuvant regimen consisted of seven once-weekly intratumoral injections of CMP-001, plus three 240-mg doses of nivolumab given at 2-week intervals. This was followed by resection, then 1 year of adjuvant therapy with nivolumab at 480 mg every 4 weeks and intratumoral CMP-001 every 4 weeks.

In an interim analysis, a major pathologic response occurred in an impressive 15 of 21 patients (71%) after 6 weeks of neoadjuvant therapy. Thirteen of the 15 had a pathologic complete response. Encouragingly, no one with a pathologic complete or near-complete response has relapsed to date.

“A pathologic complete response or near-complete response with neoadjuvant therapy appears to be a biomarker of durable disease control and is associated with excellent outcomes,” Dr. Kirkwood observed, adding that the Pittsburgh experience has been mirrored in reports from the Netherlands, Australia, and University of Texas M.D. Anderson Cancer Center, Houston, involving other neoadjuvant agents.

Other potential early biomarkers of favorable outcome with neoadjuvant therapy include CD8+ T cells in the tumor at baseline, tumor mutational burden, T-cell clonality, and a T-cell–inflamed gene-expression profile.

There were no dose-limiting toxicities or delays in surgery related to the neoadjuvant treatment.

Of note, imaging often inaccurately showed only a partial response in patients who actually had a pathologic complete response, meaning totally devoid of tumor, Dr. Kirkwood said.

Corroboration of these findings is planned in the national multicenter ECOG-ACRIN neoadjuvant trial EA6194.

“Consider referring to this trial any patients who present with bulky nodal disease for whom a treatment assessment at 4-6 weeks is desired in order to predict what the outcome may be,” he suggested.

Dr. Kirkwood reported receiving research grants from Amgen, BMS, Castle Biosciences, Checkmate, Immunocore, Iovance, and Novartis and serving as a consultant to a handful of companies.

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