Our data demonstrate that in adult pro-B-ALL a distinction should be made between pro-B-ALL cases with and without the ALL1/AF4 or the BCR/ABL chimeric genes, since the absence of both of these fusion genes correlates with a significantly better clinical outcome after intensive polychemotherapy treatment without hematopoietic stem cell transplantation.
Overall this study documents a similarly high incidence of ALL1-AF4 recombinations in children (infants excluded) and adults with pre-pre-B ALL and demonstrates the decline of the leukemic cell clone below the detection level of PCR in a remarkable proportion of patients under intense treatment protocols.