Phase I, Open-label, Non-randomized Study to Evaluate Safety of BC2059

This study is a phase I, open-label, non-randomized study to evaluate safety of BC2059 administered intravenously to subjects with proven primary or recurrent desmoid tumor that is unresectable and symptomatic or progressive. This study will utilize single patient cohorts for the first two dose levels in order to minimize sub-optimal drug exposures, followed by a conventional 3+3 dose escalation phase to achieve MTD or RP2D determined by pharmacokinetics or biologically relevant activity. Once MTD or RP2D is determined, that dose level cohort will expand to 14 patients enrolled to collect additional safety PK and PD data. If at least 1 patient has clinical benefit, the dose expansion phase will be expanded by a further 11 patients (25 total in at RP2D). The total duration of study for each subject will be dependent upon the safety, tolerability and efficacy of BC2059