Forty Seven, Inc. announced updated initial data from its Phase 1b clinical trial evaluating 5F9 as a monotherapy and in combination with azacitidine for the treatment of myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML). The data, which have matured since the abstract submission and now include additional patients and longer-term follow-up, will be presented in a poster discussion session at the 2019 ASCO Annual Meeting in Chicago, Illinois. As a result, many MDS patients receive only supportive care, and there is a clear and compelling need for new, disease-modifying options. Following recent engagement with the U.S. Food and Drug Administration (FDA), believe a single arm pivotal trial may serve as the basis for a biologics license application for 5F9 in combination with azacitidine in higher-risk MDS, and are working hard to finalize the design of potentially registration-enabling study, while continuing to enroll expansion cohorts in ongoing study in MDS and AML. As of the data cutoff of May 10, 2019, 46 patients had been treated in the Phase 1b portion of the trial, including 10 r/r MDS or AML patients who received monotherapy 5F9, and 36 untreated higher-risk MDS patients or untreated AML patients ineligible for induction chemotherapy, who received 5F9 in combination with azacitidine. Preliminary Safety Data As of the data cutoff, 5F9 was well-tolerated both as a monotherapy and in combination with azacitidine, with no evidence of increased toxicities compared to azacitidine alone. Adverse events (AEs) were consistent with what has been previously seen with 5F9, and no significant cytopenias or autoimmune-related AEs were observed in patients treated with monotherapy 5F9. Overall, the most commonly reported treatment-related AEs were expected CD47-mechanism-based effects on red blood cells, which led to a temporary and reversible anemia, and many patients in the combination cohort experienced a hemoglobin improvement over the course of their treatment with a decrease in transfusions. Importantly, no treatment- related infections were observed, and only one patient out of 36 treated with the combination experienced neutropenic fever (3%). No deaths were observed in the first 60 days on combination treatment. Only one patient out of 46 (2%) discontinued treatment due to a treatment-related AE. Preliminary Clinical Activity Data As of the data cutoff, 35 patients were evaluable for response assessment, including 25 patients with untreated higher-risk MDS or AML who were treated with 5F9 and azacitidine (11 patients with higher-risk MDS and 14 patients with untreated AML) and 10 patients with r/r MDS or AML who were treated with monotherapy 5F9.