The costliest drug on earth will treat infants with a rare disease. The market fight is just getting started.

Until three years ago, infants diagnosed with a rare disease known as spinal muscular atrophy were doomed to death or heartbreaking disability. If babies survived, many parents were forced to build virtual ICUs in their homes.

Then gene science brought a drug to market in 2016 that gave afflicted children a strong chance at life, maybe even freedom from a wheelchair.

Now, the Food and Drug Administration is poised to approve a second gene treatment for infants with SMA, and with a price tag of $1.5 million to $5 million, it will be the most expensive drug on the planet.

Even aside from its cost, the expected approval of the drug has triggered a bare-knuckle fight over market share between its manufacturer, Novartis, and the maker of the first drug, Biogen.

The intense competition foreshadows a new era of debates over cost and value as gene therapies are developed for growing numbers of rare diseases.

In this case, it has featured claims and counterclaims of safety and cost effectiveness at the pinnacle of U.S. biopharmaceutical development. It spawned a Washington public relations campaign of mysterious origin, featuring what independent communications experts characterized as coordinated op-ed columns by former Cabinet secretaries warning about the safety of the Novartis therapy.

The controversy is clouding the debate as parents, doctors, and insurance companies will soon be grappling with highly complex decisions over which drug to choose and how to pay for it. Those decisions, which will vary in individual circumstances, have to be made quickly, because the best opportunity for genetic intervention is in the very first weeks of life.

"It's a really difficult decision, and I don't envy parents who have to make this decision,'' said Charlotte Sumner, a clinician and professor of neurology at Johns Hopkins Medicine. "If I were in a parent's shoes, I would have to weigh the potential positives and negatives without necessarily knowing all the long-term data.''

In some instances, Sumner said, a case could be made for using both drugs in a single patient, further testing insurance companies' willingness to pay.

How the medical system handles these questions of safety, effectiveness and price will set a precedent for future battles. The FDA is poised to review more applications for gene therapies for inherited diseases such as hemophilia and Duchenne muscular dystrophy.

"It's sort of a heyday for rare diseases,'' said Jill Jarecki, chief scientific officer of Cure SMA, a nonprofit organization that doles out research grants.

Spinal muscular atrophy affects about 1 in 11,000 babies. Infants and older children who develop SMA have a defective or missing gene that is supposed to tell the body to maintain nerve cells that control muscles. When that gene is mutated, patients with the most severe and most common form of the disease can't hold up their heads, sit up, or even breathe normally. Most children with this form of the disease die by the time they are 2 years old.

For the past few years, the only treatment was offered by Biogen, which makes a gene-altering drug called Spinraza. It must be injected several times a year throughout a patient’s life. Its price, which has drawn criticism, is $750,000 for the first year and $375,000 in each subsequent year of treatment.

The Novartis gene therapy, called Zolgensma, is perceived to have a major advantage: It will be given to a patient once, and the genetic effect is supposed to last forever.

Neither drug works uniformly in children, and even the best outcomes leave kids with some muscle weaknesses. Still,Novartis is promoting its drug as a bigger breakthrough.

"It's the most optimal treatment you're going to have for these kids,'' said David Lennon, chief executive of AveXis, the subsidiary that developed the therapy. AveXis was purchased by Novartis for $8.7 billion a year ago.

Novartis says its drug will be more cost effective in the long run, if it works as anticipated.

"We're talking about something that's completely different, and the price reflects something that's completely different,'' Lennon said. "Whatever the sticker shock is for upfront payment, let's remember that over 10 years you're going to be spending over $4 million'' for Biogen's drug.

Separately, a trade publication recently quoted another high-ranking Novartis executive as saying the repeated spinal injections required in the Biogen treatment caused post-traumatic stress in young patients. Novartis did not respond to a question from The Washington Post about the quotation.

Biogen is waging a preemptive defense to protect its dominant market position. Sales of its SMA drug rose to $1.7 billion in 2018, up from $884 million in 2017.

The company is highlighting the drug’s positive safety profile, which is not only strong but also far better understood (with 7,500 patients around the world). At the same time, the company is attempting to sow doubt about the safety of the Novartis drug by highlighting the new product’s small clinical trials. Biogen also is raising questions about two infant deaths in those trials.

"Forever is great if you're getting nothing but benefit, and forever is not so good if there are safety issues,'' Alfred Sandrock Jr., Biogen's executive vice president and chief medical officer, said in an interview. Sandrock said there has not been sufficient transparency around adverse events in the Novartis clinical trials.

"We hear reports about serious adverse events and even deaths,'' he said, referring to the two infant deaths in the clinical trials,"and I'm not getting all the information I need as a doctor to make that decision myself.''

Novartis counters that it has been transparent about adverse events in trials of its therapy. One death was deemed unrelated to the Novartis treatment by an independent review board, it said. The second death is under review and Novartis acknowledges it may have been linked to its gene therapy. It said an autopsy has not yet been completed in the death of the second child.

The competing claims of safety and effectiveness revolve around the different ways the drugs work.

The Biogen drug works by temporarily repairing a backup gene so the body will create protein required to preserve motor neurons. The drug must be injected directly into the spinal fluid in the back, with four injections in the first two months followed by a single injection every four months for the life of the patient. Pain from the injections is a side effect.

The Novartis drug's one-time infusion introduces a virus to act as a "vector'' and transfer a permanent replacement of the defective gene into the body.

Gene therapy using viruses attracted negative scrutiny in 1999 after an 18-year-old patient, Jesse Gelsinger, died when an experimental gene therapy treatment at the University of Pennsylvania triggered a massive immune response in his body. Since then, the vector technology has advanced, while the federal government says it has added stronger oversight and contends more is understood about the risks.

The scientific issues were drawn into the political sphere in recent months by high-profile authors: Tom Price, President Donald Trump's former secretary of health and human services, and Bill Richardson, former energy secretary in the Clinton administration. Their names appeared atop two of five published columns that made strongly similar assertions about potential health dangers associated with the Novartis treatment.

Richardson, also a diplomat and former governor of New Mexico, wrote the first, landing strongly against the Novartis drug with a Feb. 14 op-ed in the Washington Times.

"Has [Zolgensma] been tested enough for assurance that the therapy won't go awry - especially considering that a treatment for SMA already exists?'' Richardson wrote, citing the Gelsinger tragedy.

Three conservative political operatives and pundits - Jared Whitley, Brian McNicoll and Peter Ferrara - wrote similar, successive columns that appeared in early March in RealClear Health, the Washington Times and American Thinker.

Then Price's article, also citing Gelsinger's death and warning of the risks of gene therapy, appeared in U.S. News & World Report on April 10. Price, who was HHS secretary for less than a year before he resigned in 2017 amid questions about his government-paid travel, asserted the Novartis treatment should not be "rushed to market unchecked.''

Independent public relations experts contacted by The Washington Post to review the opinion articles said they were a probable example of a coordinated public relations campaign, aimed at swaying regulators or lawmakers against the Novartis drug.

The ethical problem with the pieces, they said, is that there is no disclosure of who organized the effort.

They appeared to be "a coordinated, consolidated effort within a short period of time,'' said Priya Doshi, a professor of communication at American University. "This isn't something on people's radars. To me this is an attempt to put something on the agenda that isn't there already.''

The Washington Times and U.S. News and World Report did not immediately respond to requests for comment. American Thinker's editor, Thomas Lifson, said he would look into it. Carl Cannon, executive editor of RealClear Media Group, the parent of RealClear Health, said although "dissemination of talking points is an unattractive feature of modern political discourse,'' RealClear hopes people on the other side of any issue will submit a response.

Sandrock, Biogen's chief medical officer, said he was not aware of the articles and had no knowledge of how they came into existence. Later, Biogen, through a spokeswoman, offered a partial denial.

"Biogen has not been in contact with the authors of these articles,'' spokeswoman Nina Varghese said in an email. She pointed out that Biogen has its own experimental gene therapy treatments in its pipeline.

Varghese would not comment when asked whether Biogen used a consulting firm or public relations intermediary in the case of the five op-ed articles.

Of the authors, only Richardson responded to requests for comment. In an emailed statement, he said he fully stands behind his column. "I didn't contact nor did I speak with anyone from any of the companies mentioned in my piece nor do I have a financial relationship with them," he said.

Richardson did not respond to additional questions about who, if anyone, asked him to write the article, where he got the information it contained, or if he had any contact with an intermediary who could have been acting as an agent for a company.

Lennon, the AveXis chief executive, said he was aware of the articles and said none of the authors reached out to Novartis. He said he was confident the articles would have no effect on the FDA's review.

"These are not people with medical or scientific backgrounds who really have a thorough understanding'' of gene therapy, he said of the authors. "Where it is coming from? I have no idea.''

Another debate is percolating, about cost-effectiveness: How can society afford drugs with multimillion-dollar price tags for a single patient?

Specialists in rare diseases say they do not expect that families of patients will have to pay the sky-high costs of gene therapy, and that the bills will be picked up by government Medicaid programs and private insurance.

Rare-disease treatments typically are not the sort of drugs that trigger accusations of price-gouging in Congress, like unwarranted spikes in generic prices. Also, with only a few hundred new patients a year, the costs are not going to break the health-care bank.

But Biogen's price has already been assessed by some independent experts as beyond the limit of cost-effectiveness.

Insurers will be grilling companies such as Novartis and Biogen on how they set their prices, and they will want strong evidence that patients will benefit from the treatments, said Susan Cantrell, chief executive of the Academy of Managed Care Pharmacy, which represents pharmacists who participate in managed care insurance.

"The game has certainly changed'' with the advent of hugely expensive, complex drugs, Cantrell said. "We can't afford to pay for things if they don't work.''

But the benefit of gene therapy to a patient with a rare, crippling disease is difficult to calculate in terms of cost effectiveness, said Jarecki, the chief scientific officer of Cure SMA.

Even the most incremental muscle declines can have a devastating impact on an individual, "if a patient could no longer use their hand, or no longer push a mouse on their computer, or push a joystick on their wheelchair.

"If a patient in a wheelchair can feed themselves or brush their teeth, that is a huge change in independence for them.''