Blue Cross of Massachusetts will not cover controversial Alzheimer’s drug

A Rhode Island resident receives an infusion of Aduhelm in June. The Food and Drug Administration approved Aduhelm to treat cognitive impairment. But many experts said there wasn’t enough evidence to prove the drug was effective — though it sometimes caused side effects, such as brain swelling.Jessica Rinaldi/Globe Staff

Blue Cross Blue Shield of Massachusetts, the state’s largest private insurer, said Thursday that it would not cover a controversial new drug for Alzheimer’s disease, dealing another blow to Cambridge drugmaker Biogen.

Blue Cross said it reviewed clinical studies and talked to specialists before concluding that Aduhelm, priced at $56,000 a year, is “investigational,” or unproven.

“The clinical evidence for Aduhelm, though promising, does not clearly demonstrate that the potential benefits of the drug outweigh the known risks,” company officials said in a statement. They said members and physicians can request individual consideration — but noted that no one, so far, has requested coverage for the drug.

Blue Cross, which has 2.8 million members in Massachusetts, joins Point32Health, the state’s second-biggest insurer, in deciding not to include the drug in its coverage. Point32Health includes Tufts and Harvard Pilgrim health plans. Several Blue Cross plans in other states have also rejected the drug.

In June, the Food and Drug Administration approved Aduhelm to treat cognitive impairment, offering hope for patients and families struggling with a terrible disease with limited treatment options. But the decision was widely criticized. Many experts said there wasn’t enough evidence to prove the drug was effective — though it sometimes caused side effects, such as brain swelling.

Aduhelm is a monoclonal antibody that’s administered through monthly intravenous infusions.

Biogen on Thursday said Aduhelm has been studied in thousands of patients and should not be called “investigational.”

“The FDA approved Aduhelm … based on its benefit-risk profile and data from more than 3,000 patients,” a Biogen spokesperson said. “We believe patients and their families deserve to have choice and access to FDA-approved treatments, including the only Alzheimer’s disease treatment that addresses a defining pathology of the disease.”

A growing number of organizations have been skeptical of Aduhelm, which had been billed as a blockbuster drug.

Mass General Brigham, the largest health care provider in Massachusetts, said last week that it would not offer the treatment to patients because of concerns about safety and effectiveness. The Cleveland Clinic, Mount Sinai Health System in New York, and Providence in Renton, Wash., made similar decisions in July.

Most of the 6 million Americans who have Alzheimer’s are over 65 and get their insurance coverage through Medicare. Federal officials at the Centers for Medicare & Medicaid Services are still reviewing how to cover Aduhelm; the process is expected to take several more months.

Just over 100 patients with Alzheimer’s had been treated with Aduhelm as of Sept. 11, according to a report in STAT — well below Biogen’s projections for the drug.

The drug targets a sticky protein called amyloid that clumps into plaques in the brains of people with Alzheimer’s. Some doctors believe amyloid buildup causes cognitive impairment, although that theory is unproven and fiercely contested.

Jonathan Saltzman of the Globe staff contributed to this report.