This smart, beautiful 25-year-old woman is the love of Keith Knapp's life, and she is dying.

The young married couple from Folsom, Calif., has already exhausted all approved treatments for the rare and deadly kidney cancer with which Mikaela Knapp was diagnosed in October, only two years after the high school sweethearts wed.

But he's not giving up on her.

"Mikaela's always been my rock," Knapp, 24, told ABC News. "You know she's in a lot of pain. She's facing death at the age of 25. She's just such a fighter."

Knapp is mobilizing a groundswell of Internet support to pressure the U.S. Food and Drug Administration to allow compassionate use of a promising drug still being tested, but not yet approved, called anti-PD-1 immunotherapies.

"We just need someone to say that they're going to provide us with the drug, and we're not going to give up until we get that," Knapp said of the drug, "which enables the body to attack the cancer by inhibiting a cloaking mechanism that tumors use to disguise themselves from the immune system."

And the social media blitz has momentum, from the Facebook page that declares "We Got This," to Twitter, both pushing to the change.org petition that now hovers at about 200,000 supporters.

Mikaela has made YouTube appearances from her northern California hospital bed thanking everyone for their support.

Her situation is similar to 7-year-old Josh Hardy's, who has survived cancer four times, his parents said, but has been in the intensive care unit since January fighting a virus that causes the common cold. A drug company agreed this month to give him an experimental antiviral drug after an online campaign.

But some in the medical world worry about the social media pressure put on doctors, pharmaceutical companies and the FDA by masses moved by emotion rather than science.

"You'd like that to be a decision that's made by people that are caring for her, not by the pressure put on by a social media campaign," said Dr. Richard Besser, ABC News' chief health and medical editor.

Bristol-Myers Squibb, one of the companies developing the immunotherapy drug that Mikaela and her husband are attempting to make available for her, told ABC News, "While nivolumab [their version of the drug] has demonstrated potential based on early (Phase 1) data, there is not enough information on its use in humans at any given dose to establish a benefit-risk profile that would support its use outside of a well-controlled clinical trial.

"We empathize with patients who have limited treatment options and will continue to assess available data on nivolumab to determine if the established benefit-risk profile allows for expanded access use outside a well-controlled clinical trial in the future."