Alex Vlahos, a 6-year-old cancer victim whose...

Alex Vlahos, a 6-year-old cancer victim whose desperate search for a bone marrow donor was aided by the comeback of San Francisco Giants pitcher Dave Dravecky from cancer surgery, still awaits a suitable donor.

More than 7,000 people have undergone preliminary tests for compatibility with Alex, who suffers from T-cell leukemia. But it now appears that Alex’s 2-year-old brother Gregory may be the best hope for a bone marrow donor, though he is not a perfect match.

The Vlahos family is pinning its hope on an intensive last-minute drive. The goal is to test as many as 1,000 additional people before Thursday, when the family plans to travel to Seattle’s Fred Hutchinson Cancer Research Center, where Alex will undergo an 18-day series of tests and conditioning followed by the bone marrow transplant.

Dravecky, with aide from San Francisco radio station KNBR, has helped raise over $100,000 by urging donors to come forward during his dramatic comeback to major league baseball this month.