Pembrolizumab Receives FDA Approval for Adjuvant Treatment of Stage IIB or IIC Melanoma

On 3 December 2021, the FDA (US Food and Drug Administration) approved adjuvant treatment for stage IIB or IIC melanoma in adult and pediatric patients (age ≥12) after complete tumor resection (surgical removal), using protective pembrolizumab (Keytruda, Merck) immunotherapy.

In cancer, adjuvant treatment is given after the main treatment to reduce the likelihood of recurrence.

In stage II melanoma, cancer cells have grown deeper into the skin or have higher-risk features, but have not spread to lymph nodes or beyond. Despite no lymph node spread, stage II melanoma is known to recur in up to 40-50% of patients after surgery. Before this approval, we had no adjuvant treatment option for stage II melanoma.

Immunotherapy Reduced Cancer Recurrence Risk by 35%

Pembrolizumab's efficacy was evaluated in a multicenter, randomized (1:1), double-blind, placebo-controlled clinical trial of 976 patients with completely resected stage IIB or IIC melanoma: KEYNOTE-716.

Patients were randomized to 200 mg pembrolizumab, or a pediatric (age ≥12) intravenous dose of 2 mg/kg (up to a maximum of 200 mg), every three weeks for a total of 17 cycles (1 year) until recurrence or unacceptable toxicity, or to placebo for up to one year.

Stage IIB melanoma was present in 64% of patients and stage IIC disease in 34.8%.

The main efficacy outcome measure was investigator-assessed recurrence-free survival (the risk of cancer recurrence was measured).

Results

• At the first interim analysis in KEYNOTE-716, patients randomized to pembrolizumab rather than placebo had a 35% reduction in recurrence risk. HR: 0.65; 95% CI: 0.46, 0.92; p=0.0132).
• At month 12, recurrence-free survival was 90.5% in the pembrolizumab arm versus 83.1% with placebo.
• Median recurrence-free survival was not reached because cancer had not recurred in more than half the patients in either arm.

The most common adverse reactions (≥20%) reported in KEYNOTE-716 were fatigue, diarrhea, itching and arthralgia.

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