Cytogenetic Remission Status after Induction Chemotherapy for AML and High-Risk MDS Predicts Long-Term Outcome.

Cytogenetic findings at diagnosis have an important impact on prognosis in AML and MDS. Therefore, treatment is commonly stratified according to karyotype. Another important prognostic factor is remission status after induction chemotherapy. However, the diagnosis of remission, and the resulting treatment decisions, are usually not based on cytogenetic findings, but rely on peripheral blood counts and bone marrow blast cell counts. We analysed the prognostic impact of cytogenetic remission status in 115 patients with abnormal karyotype who received induction chemotherapy because of AML (n=102) or MDS (n=13). Initial karyotypes were as follows: 14x t(15;17), 9x t(8;21), 5x inv(16), 55 intermediate-risk, and 32 complex karyotypes. The following induction protocols were used: 38x TAD, 4x HAM, 25x Ida-Ara, 36x ICE, and 3x other protocols. Eleven patients received induction chemotherapy plus ATRA. 23 patients underwent allogeneic transplantation after induction therapy, either as late consolidation in cytologic remission (CR), or as standard treatment in high-risk patients. 78 patients achieved CR, 21 achieved partial remission (PR), and 16 patients were non-responders (NR).

There were 26 patients who reached cytological CR but still showed an abnormal karyotype after induction. 17 of these 26 patients had been classified as standard-risk and therefore did not receive intensified consolidation. In 59 patients, a normal karyotype was found after induction therapy. 24 of 28 patients belonging to low-risk cytogenetics (t15;17, t8/21, or inv16) achieved cytogenetic complete remission (CCR). The CCR rate was much lower in patients with intermediate-risk cytogenetics (24/55) and patients with complex karyotypes (11/32). Median survival in the group achieving CCR was 40 months, as compared to 11 months in patients with persistence of abnormal karyotype after induction (p<0,00005). The difference remained highly significant when calculated only for patients with complex or intermediate-risk karyotypes (median survival 29 vs 11 months).

Conclusions: Cytogenetic analysis after induction chemotherapy is useful to detect residual disease and therefore provides meaningful information in addition to cytology. Achieving cytogenetic remission after induction therapy is strongly correlated with a better long-term outcome. Patients with a persisting abnormal karyotype must be regarded as high-risk patients who should receive intensified treatment.