War against cancer can be won from within our own bodies

A NEW wave of experimental cancer drugs that directly recruit the immune system’s powerful T cells are proving to be immensely effective weapons against tumours, potentially transforming the $100bn global market for drugs that fight the disease.

But top oncology researchers are concerned about the two emerging technologies, citing dangers seen repeatedly in clinical trials including the potentially fatal buildup of toxic debris from killed tumour cells and damage to healthy tissue.

Such side effects can block regulatory approval if they are not controlled, researchers and drug company executives say.

In some trials, the two new approaches, known as CAR T cells and bispecific antibodies, have eliminated all traces of blood cancers in 40%-90% of patients who had no remaining options. The drugs could reap annual sales in the tens of billions of dollars for their manufacturers, especially if they can also eliminate solid tumours in such terminally ill patients.

CAR T cells, or chimeric antigen receptor T cells, are T cells that have been removed from the body and have been attached through genetic engineering to an antibody fragment that recognises a specific tumour protein. T cells are an especially powerful disease-fighting kind of white blood cell. The result is a drug with the killing power of a greatly enhanced T cell, combined with the tumourspotting ability of an antibody.

Bispecific antibodies are a twist on conventional antibodies, Y-shaped proteins whose two arms grasp for the same protein target found on cancer cells.

With bispecifics, one arm of the antibody typically grasps a cancer cell while the other arm takes hold of T cells, bringing the mortal enemies into contact. The T cell punches holes into the adjacent tumour cell and injects deadly enzymes. Conventional antibodies, by contrast, do not directly recruit T cells.

“Unleashing the killing power of the T cell directly on the tumour cells allows a large increase in potency of these antibodies,” says Dr David Scheinberg, chairman of molecular pharmacology at Memorial Sloan Kettering Cancer Center.

excitement over these therapies have helped boost interest from companies including Amgen and Roche and have fuelled a jump in the share prices of smaller firms such as Kite Pharma, Juno Therapeutics and Bluebird Bio.

“We take patients that have failed every treatment, every chemo combination, that have just two to six months to live. You give them a CAR, and within three to four weeks you children, is diagnosed each year in an estimated 6,020 Americans, killing about a fourth of them.

One third of patients in the Amgen study had no detectable cancer for nearly seven months after receiving the drug through a month-long infusion.

A main hope for Blincyto is that it will keep patients alive until they can receive stem cell transplants, their best chance of a possible cure.