The approval is based on the results of clinical trials conducted by Dr. Antoni Ribas of the University of California-Los Angeles (UCLA) and colleagues, in which they tested the drug on more than 600 patients with advanced melanoma who had not responded to previous therapies.
In one study, the team treated 173 patients with either 2 milligrams per kilogram (mg/kg) of Keytruda or 10 mg/kg of the drug. The team found that 24% of patients who received the 2 mg/kg dosage of Keytruda experienced tumorshrinkage of more than 30%, while a smaller percentage of patients given the 10 mg/kg dose had tumor shrinkage.
The tumors did not regrow in these patients, and the drug’s effects remained for at least 1.4-8.5 months, with some patients seeing effects for even longer.
In another study testing the safety of Keytruda in 411 patients with advanced melanoma, the team found that severe side effects – such as problems with the lung, colon and liver – were rare. The most common side effects were fatigue, cough, nausea, rash, itchy skin, reduced appetite, constipation, diarrhea and joint pain.
Keytruda ‘a very significant advance in the treatment of melanoma’
Keytruda is an immunotherapy drug. It attacks PD-1 – a protein expressed by immune cells that interferes with the effectiveness of the immune system. By targeting this protein, Keytruda encourages immune cells to attack cancer cells.
Past attempts to treat the cancer by boosting the immune system had failed because the PD-1 protein hindered its activity. But finding a way to target the protein is what researchers deem a breakthrough in melanoma treatment.
Dr. Ribas says:
“This drug is a game changer, a very significant advance in the treatment of melanoma. For patients who have not responded to prior therapies, this drug now provides a very real chance to shrink their tumors and the hope of a lasting response to treatment.”
One of the patients involved in the clinical trials, 74-year-old Tom Stutz, was diagnosed with advanced melanoma in June 2011. The cancer had spread to his lung, liver and other areas of his body. As a result, Stutz was on oxygen and unable to walk.
Although he felt he had little chance of survival, Keytruda shrank his tumors by 90% and halted regrowth. He is now off oxygen and is able to walk.
“It’s the little things that make me happy now,” says Stutz. “I’m very appreciative that I get to get up in the morning, go into my backyard and see my garden. I’m able to be with my children and grandchildren, go on vacations with them. I was close to the end of the road, as far as you can get to the edge of the cliff, and I was pulled back by this treatment.”
Dr. Ribas and Stutz talk about Keytruda in the video below: