PHST001-101 is a multicenter, open-label, Phase 1 study of PHST001 in patients with advanced solid tumors. The study design includes a Dose Escalation Phase and a Dose Expansion Phase, and will enroll patients with advanced relapsed and/or refractory solid tumors. The study's primary object is to evaluate the safety and tolerability of PHST001 and determine the RP2D (Recommended Phase 2 dose) of PHST001.