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The large gray areas on the left hand image show the spread of melanoma tumors to the lung. On the right hand side, the tumors have shrunk after treatment.
Pembrolizumab hailed as 'miraculous' in skin cancer trial
A pioneering new drug appears to have cured a British man with advanced skin cancer who had been given just months to live. The drug, pembrolizumab, is the latest in a new generation of treatments that prevent cancers shielding themselves from the immune system. It was tested on melanoma - the most dangerous form of skin cancer - because the prospects for patients with advanced forms of this disease are so bleak.
Pembrolizumab is a synthetic antibody that blocks a biological pathway called programmed cell death 1 (PD-1) which cancers activate to suppress the immune system. In healthy individuals, PD-1 is part of the process that applies a "brake" to the immune system and prevents it running out of control. Without the brake, there is a risk of a harmful inflammatory reaction - a potential serious side-effect of the new drugs.
In a trial of 411 patients evaluating pembrolizumab - 69% of patients survived at least a year. This means a boost survival rates of melanoma from one in ten to nearly three in four. The result is considered remarkable because all had highly advanced melanoma and a very poor prognosis.
Currently one-year survival rates for untreated patients diagnosed with advanced stage four melanoma are just 10% for men and 35% for women.
Warwick Steele, a 64 year old television engineer from Ruislip, west London, had undergone six months of treatment with pembrolizumab, which is injected into the bloodstream. Doctors were astonished when after just three months his tumours had almost disappeared. Since then they have shown no sign of returning - and in fact have shrunk even further.
Before the treatment started he could barely walk because the melanoma had spread to one of his lungs and he found it hard to breathe. "I got tired simply standing up and was literally too exhausted to shave. But now I feel back to normal and can do gardening and go shopping", Steele remarks. Scans of his lungs - shown above - reveal that after just three infusions, the drug appears to have completely cleared the cancer from his lung.
More Trials Necessary
Doctors are urging caution. The results which have been published are of Phase I, early stage trials. Much larger Phase III trials are underway involving many UK hospitals. Only when they report, in about a year's time, can clinicians be sure what the likely benefits will be.
Like all drugs, the experimental treatments have side effects. Warwick Steele said he experienced night sweats and even had two brief blackouts when on the new drug. But he said it was well worth it, and doctors were now treating these symptoms.
Clinicians do not yet know the true extent of how pembrolizumab might affect survival. After 18 months, 62% of patients were still alive and undergoing treatment. In addition, around 80% of patients responded to the drug - an unusually high proportion. A total of 72% experienced tumour shrinkage, including 39% whose tumours were more than halved in size, according to one kind of assessment.
Additional data showed that the drug also reduced the size of advanced non-small cell lung cancers by up to 47%. Pembrolizumab's manufacturer, the pharmaceutical company Merck Sharp & Dohme, is expected to apply for a European licence to market the drug within months.
Source: The Independent, BBC News
Photo credit: BBC News