Engraftment of AML samples in NOD/SCID mice. The percent CD45⁺ cells in mouse marrow was determined for each sample 8 weeks after IV injection of 10⁷ cells. Each point represents the mean percent engraftment in the bone marrow of all mice injected with cells from an individual patient sample (mean, 3 mice per sample; range, 1 to 10 mice). The numerical values shown are the means for each group of samples. (A) Influence of cytogenetic abnormalities. Changes associated with a poor prognosis included inv(3), +8, 11q23 rearrangements, t(9;22), del(20q), del(7q), +13, t(12;22), and a variety of complex abnormalities. Changes associated with a good prognosis included inv(16) or variants, or t(15;17). There was a trend toward higher levels of engraftment with samples with poor-risk cytogenetic features (P = .06). (B) Influence of FAB subtype. Fifty-seven of the 61 samples could be classified into AML subtypes according to FAB criteria. The mean engraftment levels obtained from each subtype are shown. Levels of engraftment were lower with samples with FAB subtypes M3 (P = .002) and M2 (P = .06) than with other subtypes. (▴), AML samples with cytogenetic abnormalities with a poor prognosis; (▪), samples with cytogenetic change with favorable prognosis; (•), samples with normal cytogenetics and intermediate prognosis.