Oncology · 2010
Ipilimumab improves survival in metastatic melanoma
Ipilimumab is an anti-CTLA-4 monoclonal antibody (CTLA-4 = cytotoxic T-lymphocyte-associated antigen 4)
For decades, metastatic melanoma carried a median survival measured in months, and no drug had moved that number in a randomized trial. Dacarbazine had been a standard agent since the 1970s, producing response rates around 15% with no demonstrated survival benefit. Interleukin-2 worked in a small fraction of patients but carried severe toxicity. By the late 2000s, oncologists treating stage IV disease had little to offer beyond enrollment in trials.
The answer came not from a cytotoxic drug but from releasing a brake on the immune system. James Allison's laboratory at the University of California, Berkeley had spent years studying CTLA-4, a protein expressed on activated T cells that dampens their response. His work in the 1990s showed that blocking CTLA-4 with an antibody unleashed T-cell activity against tumors in mice. Bristol-Myers Squibb developed ipilimumab as the clinical translation of that concept.
The 2010 phase 3 trial, led by F. Stephen Hodi at Dana-Farber Cancer Institute, enrolled 676 patients who had progressed on prior therapy and randomly assigned them to ipilimumab alone, ipilimumab plus an experimental gp100 peptide vaccine, or vaccine alone. Median overall survival reached 10.1 months in the ipilimumab monotherapy arm versus 6.4 months in the vaccine-only arm. The result that received most attention was the tail of the survival curve: approximately 20% of ipilimumab-treated patients were alive at three years, a figure seldom seen in this disease.
The trial also introduced oncologists to a class of toxicities they had not managed before. Immune-related adverse events, including colitis, hepatitis, dermatitis, and hypophysitis, required prompt recognition and corticosteroid treatment. Managing these events became a required competency in oncology, and guidelines for immune-mediated toxicity were developed across specialties. Steven O'Day contributed to the trial as a co-investigator and helped characterize the management of these events.
The FDA approved ipilimumab in March 2011. The finding that CTLA-4 was a viable target validated the broader concept of immune checkpoint blockade, and it was not long before the PD-1 pathway yielded a second class of agents with higher response rates and a better tolerability profile. Allison shared the 2018 Nobel Prize in Physiology or Medicine with Tasuku Honjo. The 3-year survival rate that ipilimumab established as a benchmark has since been exceeded by combination checkpoint regimens in some melanoma subgroups.
Key People
- James Allison — Developed CTLA-4 blockade as a cancer treatment concept; 2018 Nobel laureate.
- F. Stephen Hodi — First author of the phase 3 trial; principal clinical investigator at Dana-Farber.
- Steven O'Day — Co-investigator; helped characterize immune-related adverse event management.
- Tasuku Honjo — Discovered PD-1; shared 2018 Nobel Prize for immune checkpoint work.
N Engl J Med 2010;363:711-723
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