The US is the greatest developer of new medicines, a position reached by being able to attract the best talent, wherever it is found.
The United States is the world's greatest developer of new medicines, a position reached by being able "to attract the best talent, wherever it is found," they wrote in a letter to science journal Nature Biotechnology.
"At a stroke, the new administration has compromised years of investment in this national treasure," reads the missive.
The letter bears the signatures of 166 founders and leaders of pharma and biotech companies such as Biogen, Ironwood Pharmaceuticals and Incyte, along with research institutions including the Massachusetts Institute of Technology and Harvard Business School.
The US biotech industry relies on researchers, clinicians, entrepreneurs and business executives from all over the world, wrote the group.
"They discover and develop therapies that drive US biomedical innovation and deliver new medicines to patients, not only in America but also across the globe."
A 2014 study, the letter said, found that 52 percent of the 69,000 biomedical researchers in the United States were foreign-born.
"The United States has led the world in medicine production for decades, not only because of its ability to finance drug discovery, but also because, more than any other country, the United States represents opportunity regardless of borders, gender, race, sexual orientation or political cast," they wrote.
Now, foreign-born colleagues in America are fearful of the future, and those abroad employed by US-based companies were cancelling trips.
The actions taken by the Trump administration "were poorly conceived and implemented," the letter continued. "They have raised deep fears and concerns across the biotech industry."
"If this misguided policy is not reversed, America is at risk of losing its leadership position in one of its most important sectors."
The move will "slow the fight against the many diseases that afflict us," wrote the group, with resultant economic losses for the United States.
A US appeals court was set to hold a hearing on Tuesday over President Trump's controversial travel ban, which the government is defending as a "lawful exercise" of his authority.
The White House on Monday urged the court to reinstate the ban in the interests of national security three days after a federal judge barred enforcement of the controversial measure in a high-stakes case that looks increasingly likely to be settled by the US Supreme Court.