18562 Background: Elderly patients (pts) ≥60 years with acute myelogenous leukemia (AML) have lower response rates, and higher morbidity and mortality than younger pts when treated with cytotoxic induction therapy. Common disease-related factors that predict poor response in the elderly are adverse cytogenetics and secondary leukemia (following antecedent hematologic disorder or exposure to chemotherapy). Pt-related factors such as ECOG performance status (PS) and organ dysfunction affect treatment decisions due to poor tolerability and early death. Cloretazine, a novel alkylating agent has significant activity in AML and MDS with a favorable safety profile. A Phase II study of monotherapy induction was conducted in elderly pts with AML or high risk MDS (N = 105, median age 72, range 60–88), with a 31% complete response rate and minimal non-hematologic toxicity. To describe the pts in this study considered “unfit” for 7+3 induction, disease-related and pt-related information was obtained. The Hematopoietic Cell Transplantation Comorbidity Index (Sorrer et al, 2005) (HCT-CI) is a modification of the Charlson Comorbidity Index (Charlson et al.1987), for pts considered for stem cell transplant. Seventeen medical conditions are included with weighted values predicting non-relapse mortality (NRM). Methods: Baseline demographic and pt-related data was obtained from case report forms. In addition to disease-related prognostic indicators, pt-related data was scored by the HCT-CI. Pts were grouped in risk categories for NRM by HCT-CI scores (low = 0, intermediate = 1 or 2; high ≥3). Results: Either or both disease-related poor risk factors were present in 68 pts (65%): 42 pts (40%) had unfavorable cytogenetics and 45 pts (43%) had secondary AML. No pt had favorable cytogenetics. Ninety-four (89%) pts had at least one HCT-CI comorbidity. The most common were cardiac (46%), psychiatric (28%); hepatic (25%) and controlled infection (24%). By HCT-CI, the risk for NRM was low in 10%, intermediate in 32%, and high in 57% of pts. Conclusions: The majority of these elderly pts were poor-risk by disease-related criteria or comorbidities measured by the HCT-CI. This index warrants further testing for determining NRM risk of induction regimens for elderly pts with AML. [Table: see text]