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 & Co’s Keytruda has been approved to treat advanced melanoma, an aggressive form of skin cancer, as well as several other malignancies. Former President Jimmy Carter is the most high-profile patient to have taken the drug. While checkpoint blockers have dramatically improved survival for some advanced cancer patients, only a fraction survive beyond five years, and researchers are still struggling to understand what makes those few different. AstraZeneca Plc. shocked investors in July when its combination of a checkpoint inhibitor with another immunotherapy drug failed to slow disease progression in lung cancer patients any better than chemotherapy. Another type of immunotherapy, known as CAR-T, works by re-engineering a patient’s T-cells to make them better cancer fighters. The FDA for the first time approved such a therapy, made by Novartis AG, in August, and another made by Kite Pharma Inc. is expected to follow later in the year. Initial demand is expected to exceed supply, which would force doctors into the heartbreaking position of deciding which patients gets treatment. While trial results have been impressive, the potent treatments can also cause dangerous side effects. Juno Therapeutics Inc. halted a trial after patients died of brain swelling. So far the approach has been limited to blood cancers. Expanding into solid tumors remains a hurdle.
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 Squibb Co. presented positive data about its drug Opdivo.
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, an immunotherapy approved in 2011, Bristol-Myers charges $30,000 per injection in the U.S. — a total treatment costs $120,000 — and the drug has serious side effects. CAR-T therapy is particularly hard to price. Since it’s a one-time treatment, manufacturers have only one shot at getting reimbursement, but insurers, particularly in the U.S., may balk at a large upfront payment. Novartis priced its treatment at $475,000 for a single infusion and signed a deal where it will only be paid by U.S.-government programs if patients have responded to the drug by the end of the first month. 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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