The vice president had championed the so-called right-to-try issue while governor of Indiana and later on the campaign trail. While dying patients may be willing to try anything, wider access to unproven treatments may give them no more than false hope, opponents to the proposal say. And if patients have adverse reactions, that may put a premature halt to the clinical trials necessary to show drugs’ effectiveness.

Drugmakers have resisted providing experimental medications under state right-to-try laws that have been passed in more than half of the states, including Indiana.

In a private meeting with advocates Tuesday afternoon, Pence reaffirmed his support for national legislation, said Laura McLinn, an Indiana resident whose eight-year-old son has a deadly disease known as Duchenne muscular dystrophy and was the face of right-to-try efforts in Indiana.

“He also let us know that he and President Trump have had multiple conversations about this and it’s something the president is very passionate about,” McLinn said on Wednesday in a call with reporters that was set up by the Goldwater Institute, a group advocating limited government that has pushed for right-to-try laws. The White House confirmed her account of the meeting.

Access to experimental drugs is a thorny topic that has raised ethical questions, pitting stricken families’ desperation versus the risks of hurting, or even killing patients, and having to shut down clinical studies that could have benefited others.

The Food and Drug Administration has a system in place that has authorized doctors to give experimental treatments to thousands of patients on a case-by-case basis, with the manufacturer’s approval. Existing right-to-try state laws bypass FDA scrutiny as long as the drugs have completed early safety tests. Yet drugmakers don’t like leaving the FDA out of the equation. They don’t have to provide the medication under right-to-try regulations and they often decide not to.

“Any legislation should protect the integrity of clinical trials and the FDA oversight of expanded access to maintain the best interests of patients,” the Pharmaceutical Research and Manufacturers of America, the Washington lobby group for drugmakers, said in an emailed statement. “Because investigational medicines have not been approved by the FDA and determined to be safe and effective, FDA must approve expanded access to an investigational drug before a biopharmaceutical company can provide it to a patient.”

Opponents say experimental drugs can in some cases do more harm than good, even for patients who are already terminally ill. In addition, they and their families may need to pay for the drug out of pocket because insurance wouldn’t cover an unapproved treatment.

“These drugs are not benign,” Rebecca Dresser, a biomedical ethics law professor at Washington University School of Law in St. Louis, Missouri. “We don’t hear the stories of cases where people tried drugs and experienced bad side effects so that their remaining lives were much more difficult — full of pain and suffering — than they would have been if they hadn’t tried the drug.”

Sen. Ron Johnson, a Wisconsin Republican, introduced right-to-try legislation last month that would allow patients access to experimental medications if they have a certification from their doctor and have tried or don’t qualify for all other treatment options.

Federal legislation is needed to reinforce state laws, McLinn said. Her son, Jordan, hasn’t been able to gain access to the only approved treatment for Duchenne, Sarepta Therapeutic Inc.’s Exondys 51, because he has a different mutation causing the disease.

The FDA referred right-to-try questions to the White House. Peter Lurie, FDA’s associate commissioner for public health strategy and analysis, testified last year before a Senate committee on access to experimental drugs for terminally ill patients.

“Even patients with serious or life-threatening diseases and conditions require protection from unnecessary risks, particularly as, in general, the products they are seeking through expanded access are unapproved — and may never be approved,” Lurie said at the time.

The FDA has authorized 99 percent of the 7,176 requests it received for single-patient access to experimental drugs in the fiscal years 2010 to 2015, according to Lurie’s September testimony. The FDA also attempted to make it easier for physicians to apply on behalf of their patients for experimental drug access. The process takes about 45 minutes, Lurie said.