Background: FN1501 inhibits various tyrosine kinases as CDK4/6, KIT, PDGFR, ALK and RET proteins, particularly potent on FLT3 and EGFR2. A Ph1 FIH trial for patients (pts) with solid tumors and Acute Myeloid Leukemia (AML) is on-going¹. Preclinical data showed that FN1501 inhibits the phosphorylation of FLT3 and its downstream kinase STAT5 in human acute leukemia cell lines, arrests the cell cycle inducing apoptosis and inhibits growth and proliferation of leukemia cells. It has anti-proliferation activity against other leukemia cell lines bearing FLT3 mutations, and lymphoma cell lines^{2, 3}. Methods: 26 pts with advanced solid tumors or AML enrolled in the escalation phase and received IV FN1501 on days 1, 3, 5, 8, 10 and 12 on 21-day cycles. Primary objectives are safety and MTD, secondary objectives include preliminary activity, PK and PD. Plasma PK were assessed at different timepoints pre and post dose in C1 and C2. Results: As of 6FEB20, 26 pts have been treated in 7 ascending doses of 2.5mg, 5mg, 10mg, 15mg, 22.5mg, 30mg and 40mg. A 54 mg dose cohort is on-going. No DLTs, no SAEs or deaths associated to FN1501 have been reported. 12 pts (46%) had one grade 3 or higher TEAE and 7 pts (27%) had dose interruptions due to a TEAE. Administration of FN1501 to pts with metastatic solid tumors has resulted in anti-tumor activity. 9 pts had durable stable disease across 4 doses in renal, endometrial, ovarian, gastric, appendix and thymic malignancies. One pt with serous endometrial carcinoma achieved a cPR after 2 cycles at 40mg with a 47% tumor size reduction (target lesions). As of 26Oct19 preliminary PK data showed a t1/2 of approximately 12.7-19.0 hours post-dose. Mean Cmax and AUC increased proportionally with dose and Clearance is consistent among all doses. Conclusions: This on-going Ph1trial of FN1501 is providing evidence of dose or exposure effects as a single agent in patients with solid tumors. Since FN1501 targets multiple kinases on addition to FLT3, antitumor activity beyond AML is also being observed, suggesting that the potent inhibitory effects of other tyrosine kinases, including EGFR2 may be playing a role in the regulation of cellular functions, cell growth, differentiation and angiogenesis effects. FN1501 has been well tolerated and AEs are manageable. Genomic alterations investigations are underway to identify candidate biomarkers useful for predicting sensitivity to the multiple FN1501 tyrosine kinases. Further development of FN1501 is warranted. Clinical trial information: NCT03690154