Stephen Hodi, MD, co-first author of the paper
A therapy that multiplies the effect of a natural disease-fighting
antibody has extended the lives of patients with metastatic melanoma in a
large, international clinical trial. The study's researchers will
report their findings simultaneously at the American Society of Clinical
Oncology (ASCO) annual meeting in Chicago and in the New England Journal of Medicine.
Patients in the phase III clinical study who received the drug
ipilimumab — a monoclonal antibody made by duplicating a single type of
human antibody thousands of times over — survived for an average of 10
months whether they received the drug alone or in combination with a
therapeutic vaccine known as gp100, compared to just over six months for
those who received gp100 alone, investigators found.
The four-month difference represents a 67 percent increase in survival time between the two groups.
And because it occurred in patients who were otherwise out of
treatment options — all of them having metastatic disease that spread
even after earlier treatment — the treatment demonstrates the promise of
monoclonal antibody treatment for cancer patients not helped by
conventional therapies, the study authors say.
F. Stephen Hodi, MD, director of the melanoma treatment center
at Dana-Farber Cancer Institute and co-first author of the paper, says
the findings are significant on two levels. "It is the first study to
show a survival benefit for metastatic melanoma, which is often a fatal
disease, and it is proof that this first-in-class treatment is effective
The number of cases of metastatic melanoma,
considered the most serious form of skin cancer, has increased during
the past 30 years, and its death rate is rising faster than most other
Associated with extended periods of exposure to ultraviolet rays in
sunlight, the disease is expected to be diagnosed in more than 68,000
Americans and be responsible for 8,700 deaths in this country in 2010,
according to the American Cancer Society.
There are no approved therapies for metastatic melanoma beyond
standard frontline treatments, and no previous therapy for the disease
has been proven effective in a phase III clinical trial.
Ipilimumab, developed by Bristol-Myers Squibb and Medarex, consists
of millions of copies of a human antibody that binds to a molecule on T
cells — white blood cells that patrol the body for signs of illness. The
molecule, known as CTLA-4, serves as a control switch for the immune
system's response to disease.
With no antibody attached, CTLA-4 suppresses the immune response.
Ipilimumab reverses that condition, unleashing the immune attack on
abnormal cells, including cancer cells. "It essentially takes a brake
off the immune system," Hodi says.
The new phase III trial involved 676 patients with advanced (stage
III or IV), inoperable melanoma that had worsened during prior therapy
for metastatic disease.
Patients were randomly assigned to receive one of three treatment
regimens: ipilimumab and the gp100 vaccine (which seeks to spark an
immune response by presenting the immune system with a protein fragment
associated with cancer); ipilimumab alone; or gp 100 alone.
The median survival period for patients receiving ipilimumab plus
gp100 was 10 months, compared with 6.4 months for those receiving gp100
alone. The median survival for participants receiving ipilimumab alone
was 10.1 months.
In the ipilimumab-alone group, nine of 15 patients continued to
benefit from the therapy for at least two years, as did four of 23
patients in the combination therapy group.
About 60 percent of the patients treated with ipilimumab experienced
adverse side effects to the therapy, as did 32 percent of the patients
treated with gp100.
The complications were generally immune system-related and most often
affected the skin and gastrointestinal tract. The most common included
diarrhea, nausea, constipation, fatigue, decreased appetite, and rash.
While the adverse effects could be severe and long-lasting, most of them
were reversible with appropriate treatment, the authors report.
"These findings are very encouraging and will serve as the foundation
for future studies," says Hodi. "The next step is to focus on
developing combination therapies to develop synergistic and more robust
effects as well as incorporating other antibodies that target the same
family of molecules."
The senior author of the study is Walter Urba, MD, PhD, of the Earle
Chiles Research Institute in Portland, Oregon. Steven O'Day, MD, of the
Angeles Clinic and Research Institute in Los Angeles, is the paper's
The study was supported by Medarex, Inc. and Bristol-Myers Squibb.