By Emily Stephenson
WASHINGTON (Reuters) - Democratic presidential candidate Hillary Clinton will unveil a plan this week to cap monthly out-of-pocket costs for specialty drugs, her campaign said on Monday, after a tweet from Clinton accusing companies of "price gouging" sent biotech stocks tumbling.
Clinton was expected to allude to her plan in public remarks on Monday and spell it out in more detail at a health-care forum in Des Moines, Iowa, on Tuesday, an official with her campaign said.
Clinton, who leads the field seeking the Democratic Party's nomination for president in the November 2016 election, maintained her front-runner status with about 48 percent of support in a recent Reuters/Ipsos opinion poll.
Still, she has been under pressure to take more populist stances to widen her lead over the current second-place candidate, U.S. Senator Bernie Sanders. Clinton could face more hurdles if Vice President Joe Biden enters the race.
Sanders already has introduced legislation in the Senate to crack down on what he called "skyrocketing" increases in prescription drug prices.
On Monday, shares in biotech companies such as Immunogen and Gilead Sciences dropped after Clinton tweeted that steep prices for specialty drugs were "outrageous."
"Tomorrow I'll lay out a plan to take it on," she said. She pointed to a New York Times story that said while prices sometimes rise due to drug shortages, other times prices balloon as a result of a company's business strategy of buying older drugs and turning them into expensive specialty drugs.
The newspaper reported how the price of a drug to treat a deadly parasitic infection soared to $750 a tablet from $13.50 after it was bought in August by a pharmaceutical company.
The Nasdaq biotech index skidded 4.6 percent on Monday while the S&P healthcare sector fell 1.35 percent
For more on the 2016 presidential race, see the Reuters blog, "Tales from the Trail" (http://blogs.reuters.com/talesfromthetrail/).
(Additional reporting by Chuck Mikolajczak in New York and Amanda Becker in Little Rock, Arkansas; Editing by Leslie Adler)