Relative survival following response to 7 + 3 versus azacytidine is similar in acute myeloid leukemia and high-risk myelodysplastic syndromes: an analysis of four SWOG studies

Here we quantify and compare the absolute and relative overall survival (OS) benefits conveyed by complete remission (CR) in AML and high-risk MDS, and by CR with incomplete count recovery (CRi) in AML and by hematologic improvement (HI) in MDS, following treatment with 7 + 3 versus azacytidine. We compared patients receiving 7 + 3 in SWOG studies S0106 (n = 301) and S1203 (n = 261) enrolling adults ≤ 60 years, with patients receiving azacytidine therapies in S0703 (n = 133 AML patients ≥ 60) and S1117 (n = 277 MDS patients ≥ 18). Absolute survival benefit was evaluated with 1-year, 3-year, and median OS; relative benefit was evaluated with univariate and covariate-adjusted hazard ratios. CR conveyed a relative survival advantage in multivariable analysis, with a similar relative effect of CR across studies. CR also conferred an absolute survival benefit, but with a smaller magnitude of absolute benefit in the azacytidine trials. In AML, OS was similar for CRi and failure to achieve CR/CRi. In MDS, CR conferred a survival advantage versus HI and HI versus failure. The relative survival benefit of CR was similar regardless of initial therapy for AML or high-risk MDS. With both therapies, CR has a beneficial effect on survival compared with CRi or HI.