CStone Pharmaceuticals announced that the investigational new drug (IND) application of CS5001, a potential global best-in-class antibody-drug conjugate (ADC) targeting receptor tyrosine kinase-like orphan receptor 1 (ROR1) has received a STUDY MAY PROCEED (SMP) letter from the U.S. Food and Drug Administration (FDA). CS5001 will commence in the clinic as one of the three most advanced ROR1 ADCs globally, marking another important milestone for CStone's Pipeline 2.0 strategy. ROR1 is an oncofetal protein with low or no expression in adult tissues but high expression in a variety of cancers including various forms of leukemia and non-Hodgkin lymphoma, breast, lung, and ovarian cancers, making it an ideal ADC target.

CS5001 is an ADC targeting ROR1 with multiple differentiated features including proprietary site-specific conjugation, tumor-selective cleavable linker and pro-drug technology. Results from pre-clinical studies showed that CS5001 exhibited potent and selective cytotoxicity to a variety of ROR1-expressing cancer cell lines and demonstrated remarkable in vivo antitumor activity in both hematological and solid tumor xenograft models.