Myeloid-Associated Antigen Expression Is an Adverse Factor for Complete Remission Following Induction Chemotherapy of Adult Precursor T-Lymphoblastic Leukemia/Lymphoma (T-ALL).

We retrospectively reviewed our experience of 63 adult T-ALL patients to identify clinical and pathologic prognostic factors and build a risk-stratification model for induction chemotherapy. At presentation, the patients’ median age was 30, 49 were male and 14 female, 69% had lymphadenopathy, 38% a mediastinal mass, 24% CNS involvement and 21% splenomegaly. The median initial WBC was 17.9 x 10⁹/L (range 0.10–510.0). Blasts expressed CD34 in 42% of cases, CD10 in 33% and at least one myeloid-associated antigen (CD13 or CD33) in 27%. Karyotypes were abnormal in 34% of cases. Fifty-three of 61 patients (87%) who underwent induction chemotherapy achieved complete remission (CR) on protocols including vinca alkaloids, anthracyclines and corticosteroids. On univariate analysis; age, gender, initial WBC, CD10, CD34 and abnormal karyotype did not predict CR but patients expressing at least one myeloid-associated antigen had a CR of 71% compared to 93% (P=0.03) for patients not expressing myeloid antigens. The median follow-up was 19.2 months (95% CI: 0.1–172.8). Twenty-three patients relapsed with a median relapse-free survival (RFS) of 41.6 months (95%CI: 21.6–55.9). The RFS was longer for patients with an initial WBC of 3–50 x 10⁹ and for cases expressing CD10 but neither was statistically significant (P=0.19, P=0.14). On follow-up, 34 patients died with a median overall survival (OS) of 31.3 months (95%CI: 16.8–56.8). Patients with CD10 expression had a longer median OS at 44.7 months (versus 19.2 months for CD10 negative patients) but again, the difference was not statistically significant (P=0.11). Age, gender, CD34, myeloid-associated antigen expression and karyotype did not influence RFS or OS. Our study indicates that expression of myeloid-associated antigens is an adverse prognostic factor for complete remission of adult T-ALL and should be considered for induction chemotherapy risk-stratification.