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ASCO 2013: Anti–PD-1 Antibody Produces Durable, Ongoing Response in Patients with Advanced Melanoma

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Key Points

  • An ongoing trial evaluated the safety and clinical activity of the anti–PD-1 antibody lambrolizumab in patients with advanced melanoma.
  • The interim overall confirmed response rate for lambrolizumab treatment across all dosing regimens was 38%, and the duration of confirmed response ranged from greater than 28 days to up to more than 8 months at the time of the analysis.
  • Treatment was well tolerated, with the most common treatment-related adverse events being grade 1/2.

Preliminary results of an ongoing trial suggest that the anti–PD-1 antibody lambrolizumab has significant antitumor activity in patients with advanced melanoma and is well tolerated. The data were presented by Antoni Ribas, MD, PhD, Professor of Hematology/Oncology and Surgery, and Director of the Tumor Immunology Program at the Jonsson Comprehensive Cancer Center, UCLA, at the 2013 ASCO Annual Meeting (Abstract 9009) and published online in the New England Journal of Medicine.

Data from the ongoing multicenter, single-arm, open-label phase IB trial were presented from 135 patients with advanced melanoma who were administered an initial dose of lambrolizumab between December 1, 2011, and September 6, 2012. Patients received one of three dosing regimens of lambrolizumab until disease progression or unacceptable toxicity: 10 mg/kg every 2 weeks, 10 mg/kg every 3 weeks, or 2 mg/kg every 3 weeks.

Tumor response was assessed every 12 weeks by independent, central, blinded radiographic review according to RECIST 1.1 (Response Evaluation Criteria in Solid Tumors) criteria, as well as investigator-assessed, immune-related response criteria.

Objective Response Rates

The interim overall confirmed response rate for lambrolizumab treatment across all dosing regimens was 38% (95% confidence interval = 0.25–0.44). The highest overall response rate was observed in patients receiving lambrolizumab 10 mg/kg every 2 weeks (52%); 10% of patients in this dose group achieved complete response.

The duration of confirmed responses, as measured after the first 12-week evaluation, ranged from greater than 28 days to up to more than 8 months at the time of the analysis, with 80% of responding patients continuing on treatment. The median duration of response has not been reached with a median follow-up time of 11 months.

The response rates for ipilimumab-pretreated and ipilimumab-naive patients treated with lambrolizumab were similar.

Adverse Events

As of December 2012, the most common treatment-related adverse events observed were mostly grade 1/2 and included fatigue (30%), rash (21%), pruritus (21%), and diarrhea (20%). Six (4.4%) treatment-related cases of pneumonitis were reported (all grade 1/2). A total of 17 (13%) grade 3/4 treatment-related adverse events were reported, the most common of these were fatigue (1.5%), rash (2%), and elevated AST levels (1.5%). The majority of reported grade 3/4 events occurred in patients administered 10 mg/kg every 2 weeks.

The study was supported by Merck Sharp and Dohme. Dr. Ribas has served in a consultant or advisory role for Amgen, Genentech, GlaxoSmithKline, Merck, and Novartis, and has stock ownership in Kite Pharma.

The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.


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