New cancer drugs empower body’s defense system
The early success of a new class of cancer drugs, revealed in test results released here over the past several days, has raised hope among the world’s top cancer specialists that they may be on the verge of an important milestone in the fight against the disease.world Updated: Jun 05, 2013 01:55 IST
The early success of a new class of cancer drugs, revealed in test results released here over the past several days, has raised hope among the world’s top cancer specialists that they may be on the verge of an important milestone in the fight against the disease.
The excitement has spread to Wall Street, which bid up the stocks of some of the major manufacturers of the drug — Merck and Bristol-Myers Squibb, for example — more than 3% Monday after data on their drugs was presented over the weekend at the meeting of the American Society of Clinical Oncology.
The drugs, still generally in early testing, work in an entirely new way, by unleashing the immune system to attack cancer cells much as it attacks bacteria. That could be an alternative to often-debilitating chemotherapy.
Finding ways to use the body’s own defenses has been a goal since the late 1800s, when a New York surgeon named William B Coley noticed that cancer disappeared in a patient who had a severe bacterial infection. He then began injecting bacteria into cancer patients to rev up their immune systems. His claims of success were disputed and most attempts since then to harness the immune system have not worked.
The new drugs work by disabling a brake on the immune system called the programmed death 1 receptor, or PD-1. And although the data presented at the meeting was from the earliest stage of testing only, the drugs were the center of attention here, with some doctors predicting that cancer treatment was about to shift.
Analysts, who predict billions of dollars in sales, are trying to determine which of the three front-runners — Merck, Bristol-Myers and Roche — have the best drug and how soon the drugs could reach the market. Some think it could be as early as a year and a half from now.
Harnessing the immune system is appealing for several reasons. It might be applicable to many different types of cancer. It might produce longer lasting remissions than can be achieved by chemotherapy or the newer targeted drugs. And it seems somehow more natural and holistic. Most of what is known about the PD-1 drugs is that they shrink tumors significantly in 15 to 50% of patients. It is still not clearly established, though there are some hints, that the drugs will let people live longer.
And results seen in trials, under idealized conditions, do not translate perfectly to the real world. One poster presented here looked at use in Britain of Yervoy, a melanoma drug approved in 2011 that disables a different immune system brake. Median survival has been only about half of what was seen in clinical trials. NYT