Whitehawk Therapeutics (Nasdaq: WHWK) has entered an option agreement with China's Hangzhou DAC Biotech to access the CPT113 linker-payload technology across up to five new ADC programs, including dual-payload variations. The Morristown, New Jersey-based Whitehawk, which relaunched from Aadi Bioscience in 2025 to focus on antibody-drug conjugates, will select targets and source antibodies independently while retaining global rights and full program control. Financial terms were not disclosed.
CPT113 is a camptothecin-based topoisomerase I (Top1) inhibitor linker-payload developed by Hangzhou DAC. Top1 inhibitor payloads work by inducing DNA single-strand breaks in tumor cells, triggering apoptosis — the same mechanism used by DXd in trastuzumab deruxtecan (Enhertu) and SN-38 in sacituzumab govitecan (Trodelvy). Whitehawk describes CPT113 as a differentiated next-generation payload within this class, though the specific chemical distinctions from DXd and SN-38 are not fully disclosed in company materials.
Whitehawk's approach layers its proprietary Carbon Bridge Cysteine Re-pairing (CBCR) bioconjugation process on top of the CPT113 payload. CBCR is described by the company as a site-specific conjugation method that reduces the native interchain disulfide bonds of the antibody and re-bridges the resulting free cysteines using a carbon-based crosslinker, producing a more homogeneous ADC with a defined drug-to-antibody ratio (DAR). In nonclinical comparisons against Hangzhou DAC's own CPT113-based ADC, DXC006, Whitehawk reported higher DAR and improved therapeutic index — though these data are preclinical and have not been validated in a controlled head-to-head clinical setting.
Whitehawk's existing three-asset pipeline — HWK-007, HWK-016, and HWK-206 — is separately in-licensed from WuXi Biologics (HKEX: 2269.HK) under an exclusive global development and commercialization agreement. The new Hangzhou DAC option expands the CPT113 access that already underpins those programs to cover up to five additional, internally developed candidates. The company anticipates submitting IND applications for multiple new programs within 12 to 24 months.
Both of Whitehawk's lead clinical programs are currently enrolling. HWK-007, a PTK7-directed ADC, received IND clearance in January 2026 and has completed the first dose cohort at 2 mg/kg in a Phase I trial evaluating patients with non-squamous EGFR wild-type NSCLC, platinum-resistant ovarian cancer, and endometrial cancer. HWK-016, a MUC16-directed ADC, entered Phase I first-in-human testing in March 2026 and is enrolling the first dose cohort at 2.5 mg/kg in ovarian and endometrial cancers (NCT07470853). Initial data from both programs are expected in the first half of 2027. An IND for HWK-206 is anticipated mid-year 2026.