Transhuman — Ben Bova

Luke Abramson, a brilliant cellular biologist has one joy in life, his ten-year-old granddaughter, Angela. When he learns that Angela has an inoperable brain tumor and is given less than six months to live, Abramson wants to try an experimental new therapy that he believes will kill Angela's tumor.

Her parents object and the hospital bureaucracy blocks the experimental procedure because it has not been approved by the FDA. Knowing that Angela will die before he can get approval, Abramson abducts Angela from the hospital. He plans to take her to a private research laboratory in Oregon.

Luke has turned his old SUV into a makeshift medical facility, treating Angela as best he can while they are on the road, desperately trying to keep his granddaughter alive long enough to give her the treatment he believes will save her life.

Abramson realizes that he's too old and decrepit to flee across the country with his sick granddaughter, so he injects himself with a genetic factor that has successfully reversed aging in animal tests.

As the chase weaves across the country from one research facility to another, Luke begins to grow physically younger, stronger. He looks and feels the way he did thirty or forty years ago.

But will he be able to save Angela?