"The studies presented today illustrate the progress we are making against advanced cancers that are resistant to traditional therapies," said Gregory Masters, a medical oncologist at the Helen F. Graham Cancer Center in Delaware.
"New targeted and immunotherapy drugs are emerging as viable strategies for halting the progression of these difficult diseases."
Three major studies presented at the American Society of Clinical Oncology annual conference showed promising results for treating melanoma.
Melanoma, which is expected to cause nearly 9,500 deaths in the United States this year, is typically found in the skin.
It becomes one of the hardest cancers to treat when it affects the eye.
Researchers believe they have found the first drug able to tackle advanced melanoma of the eye.
An early phase II clinical study of 98 patients found AstraZeneca's drug selumetinib led tumors to shrink for half the patients who used it.
It also more than doubled the amount of time -- to 15.9 weeks -- it took for the disease to worsen when compared with patients who received a drug developed to fight melanoma of the skin. The median survival rate rose to 10.8 months from 9.4 months.
Eight previous clinical studies had shown tumor shrinkage in only two of the 157 patients tested.
"While we are hopeful an agent like selumetinib will be commercially available in the near future, in the meantime we must continue to steer patients towards clinical trials," said lead author Richard Carvajal, a medical oncologist at Memorial Sloan-Kettering Cancer Center in New York.
A second study found that Bristol-Myers Squibb's drug nivolumab -- which targets a receptor on the surface of T-cells to boost the body's immune response to cancer -- helped late-stage melanoma patients who did not respond to traditional therapy.
The expanded phase I study of 107 patients found that 30 percent experienced tumor shrinkage, compared with historical response rates of five to 10 percent, while median survival rates exceeded those of recently approved melanoma drugs.
"I think nivolumab is a real breakthrough drug for patients with metastatic melanoma, and probably for other diseases, too," said lead author Mario Sznol, a professor of medical oncology at the Yale Cancer Center in Connecticut.
"The high level of activity observed with this drug opens up a number of avenues for future research to understand and challenge the ways tumors evade the immune system."
A third study found patients with metastatic melanoma increased their survival chances by 35 percent when Sanofi's white blood cell booster GM-CSF (Leukine) was combined with an increased dose of Bristol-Myers Squibb's immunotherapy drug ipilimumab (Yervoy).
The phase II study of 245 patients also found that those receiving the drug combination had fewer serious side effects, particularly lung and gastrointestinal toxicities.
Meanwhile, a phase III study of 592 patients with colorectal cancer showed that Merck's cetuximab (Erbitux) gives patients a roughly four-month survival advantage over those who take Genentech's bevacizumab (Avastin).
While the median time for the disease to grow after treatment was about 10 months with both drugs, the overall survival rate for patients taking cetuximab was 28.7 months compared to 25 months for those using bevacizumab.
Both drugs are already approved for use as an initial treatment when combined with chemotherapy, and this is the first study to suggest that one is superior.
"We suspected that cetuximab would produce a better response, but we didn't know this would translate into better survival," said Volker Heinemann, a professor of medical oncology at the University of Munich in Germany.