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Promising new osteoporosis drug could fill treatment gap

A large clinical trial of a new osteoporosis drug found that it stimulates bone growth and prevents fractures at least as well as the only other such drug on the market. The drug, expected to win approval from federal regulators, would offer another much-needed treatment for some of the 10 million Americans, 80 percent of them women, who have a disease that often leads to years of pain and disability, as well as early death.

Doctors who care for people with osteoporosis said they hoped the new drug would also spur price competition in an arena that has had none. The new drug would compete with a medicine made by Eli Lilly, called Forteo, that costs $2,550 for a four-week supply. A spokeswoman for Radius, the maker of the new drug, said it was the company’s policy not to discuss price.

Experts agree that new drugs are urgently needed for this debilitating disease. People with osteoporosis have bones that are fragile and break easily. Bone is naturally lost with age, but osteoporosis is an extreme, abnormal bone loss that can cause devastating fractures, particularly of the spine and hip.

Yet most patients, even those at highest risk, are not getting any treatment, according to the National Osteoporosis Foundation. The first treatment option, a class of drugs called bisphosphonates, which includes Fosamax, slows the loss of existing bone but does not build bone. Those drugs can cost just pennies a day but can have very rare side effects — a sudden shattering of the thighbone or an erosion of the jawbone — that have discouraged people from using them.

The only other option is Forteo, but its price is so high that insurers have required that patients try a bisphosphonate first.

The clinical trial of the new drug was conducted by Radius, and the results were published Tuesday in The Journal of the American Medical Association. The trial compared the new drug, abaloparatide, with a placebo and with Lilly’s drug, Forteo.

Like Forteo, the new drug must be injected daily, but it is a derivative of a different hormone, one that stimulates only bone growth. Lilly’s drug stimulates both bone growth and bone loss, though the net effect is a gain in bone.

With the Radius drug, holes in osteoporotic bone appeared to fill faster than with the Lilly drug. But the study was not large enough to determine whether that translated to fewer fractures. Both drugs were far better than a placebo. After 18 months, four women of the 824 taking the Radius drug had a new spine fracture, compared with six of the 818 taking Lilly’s drug and 30 of the 821 taking a placebo.

Radius has filed an application with the Food and Drug Administration to market the drug.

The new drug’s development grew out of cancer research. Two endocrinologists, Dr. Andrew F. Stewart, now the director of the diabetes, obesity and metabolism institute at the Icahn School of Medicine at Mount Sinai, and his mentor, Dr. Arthur E. Broadus at Yale University, tried to figure out why some cancer patients had excessive amounts of calcium in their blood. It is a dangerous condition, leading to lassitude and even coma. When the doctors studied tumors that had made patients’ skeletons release calcium, they discovered the cancer was secreting a hormone no one had ever heard of that regulated calcium levels in the blood.

But how could a hormone cause high levels of calcium in the blood by removing calcium from bones and also cause bone growth?

“It seems counterintuitive,” Stewart said. “But the magic depends entirely on how you give it.” He explained that a continuous flow of the hormone leaches calcium from bone, but that a single spike of the hormone builds bone.

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