Cancer kills more than 8 million people a year, and the number of new cases is expected to grow to 22 million by the 2030s. That gives urgency to scientists’ hopes for so-called immunotherapies, new drugs that harness the body’s defense system to attack cancer cells. While forms of the treatments have been around for decades, they once worked against just a few malignancies. New immunotherapies can target a wider range of cancers, including tumors of the lung and kidney as well as several blood cancers. Some drugs teach the immune system how to recognize and fight cancers, while others disable the mechanisms that cancers employ to defend themselves. The potential: long-lasting therapies for difficult cancers that can enhance existing treatments. The market for cancer immunotherapies could reach $35 billion a year.
The U.S. Food and Drug Administration has approved a number of immunotherapies. Drugs in a class called checkpoint blockers help to take the brakes off the immune system, unleashing the body’s killer T-cells to hunt down cancer. Merck’s Keytruda has been approved to treat advanced melanoma, a skin cancer that typically kills most of its victims within a year of diagnosis. Former President Jimmy Carter is the most high-profile patient to have taken the drug. In a study in which 279 patients took the drug every two weeks, 74 percent survived a year or longer. Keytruda has also been approved for forms of lung cancer and head and neck cancer. Bristol-Myers Squibb, whose drug Opdivo has fueled tremendous sales growth, has had a rockier road. While it's been approved for cancers including advanced melanoma and head and neck cancer, it failed a lung-cancer trial that would have widely expanded its use. Other immune therapies work by re-engineering a patient’s T-cells to make them better cancer fighters. While early results are impressive, the potent treatments can also cause dangerous side effects. Juno, one of the front-runners in this field, halted a trial after patients died of brain swelling. Kite Pharma remains in the lead, seeking FDA approval in 2017 for its first treatment. So far the approach has been limited to blood cancers. Expanding into solid tumors remains a hurdle. Ultimately, the most successful treatments may be combinations of the drugs. According to trial results published in 2015, Opdivo paired with Yervoy, a Bristol-Myers immunotherapy approved in 2011, stopped melanoma from progressing for almost a year on average, better than seven months for Opdivo alone.
Science first stumbled across the human body’s natural cancer defenses in the 19th century, when doctors noticed tumors shrinking after patients developed infections. Experiments in stimulating antibodies to fight cancer weren’t promising, so radiation, then chemotherapy, became the favored treatments despite sickening side effects. Interleukin-2, an immunotherapy drug that slowed growth in melanomas, was approved in 1992. But the drug produced aches, nausea, diarrhea and even heart attacks and strokes, so patients had to be kept in the hospital for treatment. As scientists learned more about the human genome, medicines were developed that could target parts of the body without damaging the rest. The current fascination with immune therapies was triggered in 2012, when Bristol-Myers presented data that Opdivo could treat patients with lung and kidney cancer, as well as melanoma.
The therapies are so new, no one knows how effective they will be at preventing relapses. They don’t work in every patient. So far, they’ve only been proven effective for advanced forms of cancer, so it’s possible they won’t work in earlier stages. Costs may also be an obstacle to widespread use. For Yervoy, Bristol-Myers charges $30,000 per injection in the U.S. — a total treatment costs $120,000 — and the drug has serious side effects. There’s also the lesson of history: Cures for cancer have been predicted before, only to disappoint. Among notable examples are the angiogenesis drugs of the late 1990s, which some experts predicted would end cancer in two years. Some of those drugs, which restrict blood flow to tumors, are in use today but the cure for cancer remains elusive.
The Reference Shelf
- The New Yorker published a history of cancer immunotherapy in 2012 by Jerome Groopman, a Harvard Medical School researcher.
- The American Cancer Society has a primer on cancer immunotherapy.
- Dr. Siddhartha Mukherjee examined the history of cancer and its treatment in a Pulitzer Prize-winning 2011 “biography,” “Emperor of All Maladies.
First published July 3, 2014
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