A quest by Lucie Masarová, a 15-year-old leukemia patient from Prague, to find a cure abroad ended Aug. 19 when doctors from a cancer research center in Houston, Texas, decided she did not qualify for any of their studies on new leukemia drugs.

The refusal followed decisions by doctors in Calgary to remove her from a study there after changes in her blood meant she no longer met that study's criteria. Masarová had flown to Canada in July after Czech doctors told her family more treatment here was futile.

Her removal from the Calgary study and failure to qualify for treatment in Houston seemed to be medical dead ends for Masarová, leaving only the option of a return home and palliative drugs to make her more comfortable as leukemia gradually takes her life. Yet even as the bad news set in, Masarová has shown a remarkable improvement in recent days, says a doctor traveling with her.

"In the last 10 days, she has gotten better and better, both in her appearance and blood tests," said Jan Wágner, Aug. 22. "It's quite unusual. I don't know why it's happening."

The prognosis remains grave, but Wágner, Masarová and Masarová's mother, Jitka, continue to cling to hope. They flew from Canada to Prague Aug. 22, returning from their frantic two-month journey, during which Wágner interpreted for Masarová and the family endeavored to have her admitted to the cancer study at the Anderson Cancer Center in Houston.

In Calgary, Wágner performed tests that showed that Masarová's platelet count had increased eightfold in the last month and that her hemoglobin had returned to near normal levels — striking and encouraging developments, he said, in her battle with the disease.

Masarová, still very thin, according to Wágner, but sounding as cheerful as any teenager, said by phone, hours after her returning to Prague, "I feel good. I met a lot of new friends in America. I saw a lot of things. Maybe that explains my improvement."

Wágner said that about 2 percent of leukemia patients in the late stages of the disease spontaneously recover, and that Masarová just may be one of the lucky few.

"We were afraid," said Masarová's father, Milos Masare. "We thought everything would end badly after the news from Houston. But I told Lucie we won't give up. And we won't. We'll keep fighting."

Diagnosed with leukemia in October 2003, Masarová appeared to recover from the disease following a bone-marrow transplant last winter. But the leukemia returned and by June this year had advanced to the point that, according to her doctor at the time, more treatment was useless.

Upon hearing the bad news, Masare, who lost a father-in-law and an uncle to cancer in 2004, searched the Internet for studies on new leukemia medicines that might admit his daughter, eventually finding a suitable match at the Alberta Children's Hospital in Calgary.

Masarová left Prague July 13 for Canada but was delayed for 36 hours in London while officials at Heathrow Airport debated if she was healthy enough to make her trans-Atlantic connecting flight.

The experimental treatment in Calgary focuses on thwarting the reproduction of immature blood cells by using a "false substitute" for the DNA of these cells. Leukemia attacks the body by causing unrestrained multiplication of immature blood cells at the expense of mature, essential ones.

Like many studies, the Calgary trial's primary purpose is to test a drug, not to save lives, and a month after she arrived in Canada, a key indicator in Masarová's blood — its percentage of malignant cells — increased to the point where she no longer qualified as a test case. Likewise, the Houston center disqualified her for treatment involving an experimental mixture of three drugs not because it wouldn't help her but because of her history as a patient. She had had multiple relapses, and the study required patients who had had just one.

Following the demoralizing rejection in Houston, the family's hopes have been renewed by the news that Masarová's body is now having more success at fighting the disease on its own.

"We can support her with drugs and vitamins that bolster her immune system and transfusions to stop her from bleeding," Wágner said. "Her body has to do the rest." He added, "This very thin girl is a real fighter. Cross your fingers for her."