WASHINGTON — On Aug. 30, the Food and Drug Administration approved a radical new cancer treatment that harnesses a patient’s immune system to attack tumor cells. The drug, known as Kymriah, grew out of research conducted and supported by the National Institutes of Health.

Seven weeks later, the F.D.A. approved a second cancer therapy that uses similar technology. This treatment, Yescarta, “got its start right here at N.I.H.,” said Dr. Francis S. Collins, the director of the health institutes. It was developed by Kite Pharma using technology licensed from the N.I.H.

Kymriah costs $475,000 for a one-time treatment, and Yescarta goes for $373,000.

As President Trump vows to lower prescription drug prices, consumer advocates and health policy experts are increasingly saying that the government should insist on reasonable prices for drugs developed with taxpayer funds. New pharmaceuticals can seem miraculous — Kymriah and Yescarta are made from souped-up versions of a patient’s own immune cells — but they are useless if unaffordable, patient advocates say.

“We’ve heard from thousands of patients who tell us devastating stories of skipping doses, cutting pills in half, going without food and even declaring bankruptcy because of the prices of their drugs,” said Ben Wakana, the executive director of Patients for Affordable Drugs, a consumer group. “In the absence of N.I.H. action to address this issue, patients and families will be hurt, and our system will buckle under the weight of amazing drugs we cannot afford.”