Turning cancer cell dependencies into targeted therapies

What It Covers

Andy Parker, CEO of StepPharma, explains how the company's lead drug dancadostat selectively inhibits the CTPS1 enzyme to block cancer cell proliferation across three concurrent clinical trials — relapsed/refractory lymphoma, biomarker-selected solid tumors, and essential thrombocythemia — following a €38M Series C raise.

Key Questions Answered

• •CTPS1 Selectivity Mechanism: Dancadostat achieves 1,300-fold selectivity for CTPS1 over CTPS2, meaning healthy tissues can still use CTPS2 to produce CTP normally while cancer cells dependent solely on CTPS1 are starved of DNA building blocks. This selectivity resolves the gastrointestinal toxicity that has historically blocked development of nucleotide synthesis inhibitors.
• •Solid Tumor Biomarker Selection: A high prevalence of CTPS2 loss — through chromosomal deletion or epigenetic silencing — exists across solid tumors, creating a CTPS1-only dependency. StepPharma's strategy is to screen patients for this biomarker before enrolling them in safety expansion cohorts across ovarian, endometrial, and lung cancer, targeting pan-cancer applicability from one drug.
• •Repurposing a Safety Signal: Platelet reduction, initially managed as a side effect in lymphoma and solid tumor trials by using a one-week-on, one-week-off dosing cycle, became the therapeutic endpoint in essential thrombocythemia. Nine patients enrolled in the ET Phase 2 study are all responding, with 50-patient recruitment targeted by summer next year.
• •Single-Asset Licensing Caution: StepPharma deliberately avoids outlicensing individual indications to pharma partners because doing so with a single-asset company creates structural complexity that complicates future IPO or M&A outcomes. Instead, the company is pursuing a China joint-venture model as a geographically contained partnership structure that preserves core asset integrity.
• •Pipeline-in-a-Product Fundraising Logic: Running three concurrent indications early-stage provides investors with multiple shots on goal, reducing binary risk. As trials advance toward Phase 3, StepPharma plans to narrow focus — potentially from three indications to two — because late-stage financing requires concentrated capital deployment and investors expect defined, fundable programs rather than broad exploratory pipelines.