SD ≥6 months +/- tumor regression were seen in pts with advanced ASNS-loss ovarian cancer (n=2), PD-1/L1-exposed melanoma (n=2) and NF1 mutant leiomyosarcoma (n=1)….IACS-6274 was well tolerated at biologically active doses with good human PK, significant PD target modulation and preliminary antitumor activity observed.