Outcome and Prevalence of Hyperdiploidy and Hypodiploidy in Adults with Newly Diagnosed Acute Lymphocytic Leukemia: A SWOG Study

One-hundred and eighty-five pts treated on S9400 and S0333 with successful cytogenetic (CG) analysis were included. The treatment regimens were: S9400 [Induction: Daunorubicin (D), vincristine (V), prednisone (P), PEG-asparaginase (PEG); Consolidation: Cytoxan (Cy), cytarabine (AraC), 6-mercaptopurine (6MP), intrathecal methotrexate (IT Mtx). Consolidation was followed by allogeneic stem cell transplant or maintenance chemotherapy] and S0333: Double Induction Chemotherapy [Induction 1: D, V, P, PEG; Induction 2: high dose AraC, mitoxantrone, decadron. Consolidation: Cy, AraC, 6MP, Mtx; consolidation was followed by maintenance therapy]. Karyotypes were centrally reviewed and clonal abnormalities described according to ISCN (2009). Hyperdiploidy was defined as: low hyperdiploidy [47–49 chromosomes (cs)], high hyperdiploidy (51–65 cs), near triploidy (66–79 cs), and near tetraploidy (84–100 cs). Hypodiploidy was defined as: near haploidy (25–29 cs), low hypodiploidy (31–39 cs), and high hypodiploidy (42–45 cs). When more than one cell line was present, ploidy was assigned by the most complex clonal karyotype. Hypodiploidy and hyperdiploidy were analyzed as prognostic factors for complete response (CR) rate and residual disease (RD) by logistic regression and chi-square tests; and for overall survival (OS) and relapse-free survival (RFS) by proportional hazards. Multivariable analyses were stratified by study and using the baseline variables: age, WBC, lineage, and CG risk.

The median age was 32 yrs (range 17–64), and median WBC at diagnosis 17.2 K/uL (range 0.6–396.6). CG risk was ascribed by (Pullarket V et al. Blood 2008; 111: 2563). Forty-five pts (24%) had normal CG, and 73 (39%) had poor risk CG. Fourteen pts (8%) had hypodiploidy (2: low hypodiploidy; 12: high hypodiploidy). Fifty-three pts (29%) had hyperdiploidy [40: low hyperdiploidy, 10: high hyperdiploidy (5%), 3: near tetraploidy or tetraploidy (2%)]. The CR rate for all pts was 72%; with a median RFS of 15 mos (95% CI: 12–29 mos) and median OS of 28 mos (95% CI: 21–36 mos). There was no significant association with ploidy status and age, WBC, or lineage. However, there was an increased prevalence of the t(9;22) in the high hypodiploidy group compared to the normal/pseudo diploidy group (p=0.049). Neither hypodiploidy nor hyperdiploidy were predictive of CR or RD; although pts with hypodiploidy had a higher rate of RD (p=0.062). The 2 pts with low hypodiploidy had very poor outcomes (1 had RD and died after 11 mos; the other relapsed after 3 mos from CR and died 4 mos after study registration). There were no statistically significant differences in OS, CR rate, or RFS between the ploidy groups even after adjusting for baseline characteristics in multivariate analysis. Surprisingly, when excluding pts with poor risk CG there was still a trend towards a worse RFS (29 vs. 32 months, p=0.20) and OS (40 vs. 68 mos, p=0.29) in pts with hyperdiploidy compared to normal/pseudodiploidy. In addition, the 3 pts in the high hyperdiploidy group without poor risk CG had poor OS (median 23 mos).

The prevalence of high hyperdiploidy is much lower in adults with ALL, compared to children. The prevalence of hypodiploidy and near tetraploidy/tetraploidy is comparable to that seen in children with ALL. Hypodiploidy and high hyperdiploidy were not prognostic factors for outcome in this group of patients. Given the low prevalence of these abnormalities, it is possible that larger numbers of pts may be needed to detect such a difference. The poor outcomes of pts with low hypodiploidy are consistent with findings by Moorman et al. (Blood 2006; 109: 3189). However, in contrast to Moorman's results, there was no evidence of an association of hyperdiploidy with age/WBC, and there was a trend towards a worse prognosis in this subset of patients. This suggests that the biology and prognosis of high hyperdiploidy may be affected more by WBC and age in the adult population.

No relevant conflicts of interest to declare.