There are, broadly speaking, four ways to fight cancer. You can cut a tumour out, with surgery. Or you can try one of three different ways of killing it. Radiotherapy targets tumours with radiation. Chemotherapy uses chemicals that poison all rapidly dividing cells, cancerous ones included. “Targeted therapies”, as their name suggests, recognise particular features specific to cancer cells.
Singly and in combination, these four types of treatment have contributed to a steady increase in the survival rates for most kinds of cancer. Now they may be joined by a fifth: immuno-oncology.
Modern medicine provides every reason to think that the immune system—which, after all, is there to keep the rest of the body safe—can and does attack cancers. People whose immune systems have been weakened, either by disease or by medicines designed to help them tolerate organ transplants, run a greater risk of malignancies. Many risk factors for cancer, such as a bad diet, heavy drinking, stress and smoking are known also to affect the immune system. Exercise, thanks to the boost it gives the body’s defences, can improve cancer survival rates.
But attempts to give more specific jolts have been unimpressive. Vaccines have had mixed results. The successful ones, such as the vaccine for cervical cancer, work by fending off ordinary bugs that happen to be associated with tumour formation. A true cancer vaccine—which would stimulate the immune system to recognise telltale proteins produced by cancer cells themselves—has proved elusive.
Now, though, a new generation of treatments offers new possibilities. Like targeted treatments, these new approaches often use antibodies—proteins that match up to other proteins with great specificity. Unlike the targeted therapies, though, the new treatments do not directly attack cancerous cells, but instead unleash the immune system on them.
Cancer seems to use three strategies to evade the body’s defences. One is to present itself to the body in such a way that the immune system fails to recognise it as something that should be killed. Another is to interfere with the abilities of T-cells, whose duty it is to carry out such killings and which, by hanging around for decades in the body, provide durable immunity to a given disease. Lastly, there are all sorts of ways in which the immune system as a whole can be suppressed.
Miracles are rare in medicine, and doubly so in oncology. Those encouraging—even spectacular—lung-cancer numbers hide big disparities. Although some patients get a long-term reprieve, there are more for whom checkpoint inhibitors make little difference, or even none at all.
The new treatments look promising. But they do not look cheap. Yervoy, a new drug trying to boost the ability of T-cells, costs $130,000 per patient per year, Opdivo, which is the name of another drug produced by another company, about $150,000. As more drug companies pile in, patients can hope that competing drugs will hit the market soon. But as the rich world grows older, fatter and therefore more cancer-prone, one salient question is how lucrative immuno-oncology might prove for drugs firms—and how affordable for the insurers and governments that would have to buy them.
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