AT LAST, a glimmer of hope for people with some incurable cancers. Drugs called checkpoint inhibitors can extend life by stopping cancer cells from disarming the immune system.
Some of the best results, presented recently at the meeting in Chicago, have been in lung cancer, which kills more people than any other cancer, and melanoma, the most aggressive and lethal form of skin cancer. 鈥淔or lung cancer, this is amazing because patients have very little else,鈥� says Alan Worsley of Cancer Research UK. 鈥淎nd for melanoma, it puts new weapons at our disposal.鈥�
聯This is amazing, as lung cancer patients have little else to try. For melanoma, it鈥檚 a new weapon聰
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One key finding is that patients who fare best on the drugs have a molecule called PD-L1 coating their tumour cells. When white blood cells bind to this molecule, it stops their assault and the cancer grows unchecked. Checkpoint inhibitors prevent this by blocking the binding.
In one trial, a drug called alive for at least a year, compared with 39 per cent of 290 patients on the standard drug, docetaxel. People whose cancer cells had high levels of PD-L1 lived almost twice as long if given nivolumab as those on docetaxel.
However, Worsley cautions that PD-L1 is not the only way for cancer to trick the immune system, so only about 20 per cent of patients will benefit from checkpoint inhibitors.
Combinations of checkpoint inhibitors work even better, and should raise the proportion of people who benefit. When melanoma patients, for example, took nivolumab plus a drug called ipilimumab, , compared with 3 and 7 months for ipilimumab or nivolumab alone. However, drug combinations have worse side effects, Worsley says.
This article appeared in print under the headline 鈥淐ancer checkpoint鈥�
