Vincerx Pharma and Oqory, Inc. have announced promising Phase 1a/1b data for Oqory's anti-TROP2 antibody-drug conjugate (ADC), OQY-3258, in patients with solid tumors, particularly highlighting its potential in various breast cancer subtypes. The companies also provided insights into their proposed strategic merger, which aims to advance OQY-3258 into global Phase 3 trials.
OQY-3258, also known as ESG401, is currently under evaluation in multiple clinical trials, including a Phase 1a/1b trial in patients with solid tumors (NCT04892342) and Phase 3 studies in HR+/HER2- breast cancer (NCT06383767) and triple-negative breast cancer (TNBC) (NCT06732323). The TNBC study has received Breakthrough Designation from China's National Medical Products Administration (NMPA).
Phase 1a/1b Trial Results
As of August 2024, the Phase 1a/1b study had enrolled approximately 150 patients. Data presented at the 2024 European Society for Medical Oncology (ESMO) and a recent data cut from January 2025, showed the following:
- Previously Untreated TNBC (n=25, then n=35): The confirmed overall response rate (ORR) was 76% at ESMO and improved to 80% in the January 2025 data cut. The disease control rate (DCR) was 100%, with median duration of response (DOR) and progression-free survival (PFS) not yet reached.
- Late-Stage TNBC (n=37): The confirmed ORR was 27%, and the DCR was 62%, with 6-month DOR and PFS rates of 39% and 25%, respectively.
- HR+/HER2- Breast Cancer (n=58): The confirmed ORR was 39%, the DCR was 78%, and 6-month DOR and PFS rates were 70% and 55%, respectively, with a median PFS of 7.4 months (range: 3.7-9.2 months).
- Brain Metastases (n=17): OQY-3258 demonstrated an intracranial ORR of 41%, including three complete and four partial transcranial responses. PFS was 4.6 months (95% confidence interval: 2.0-9.8 months) with OQY-3258 compared to 2.8 months (95% confidence interval: 1.5-3.9 months) for historical data with Trodelvy.
Safety Profile
OQY-3258 has demonstrated a favorable safety profile. The most common Grade ≥3 adverse events were manageable hematologic toxicities, such as neutropenia and leukopenia, which did not lead to treatment discontinuation. Notably, no Grade ≥3 rash or interstitial lung disease/pneumonitis was observed, with only one case each of Grade 3 diarrhea and stomatitis.
Strategic Merger
Vincerx and Oqory are parties to a binding term sheet for a proposed merger, where Oqory would merge into Vincerx. Post-closing, Oqory equity holders are expected to own approximately 95% of the combined entity, and Vincerx equity holders would hold approximately 5%. The merger includes a minimum fully diluted equity value of $13.66 million for existing Vincerx stockholders and requires a concurrent private offering of Vincerx equity securities of at least $20 million.
Michael King, CEO of Oqory, Inc., stated, "The compelling clinical activity demonstrated in our Phase 1a/1b trial highlights the potential of OQY-3258 to address significant unmet needs in TROP2-expressing tumors. With its optimized serum-stable linker design, OQY-3258 has shown a markedly lower incidence of severe off-target toxicity compared with other marketed TROP2 therapies."
Raquel Izumi, Ph.D., Acting CEO of Vincerx, added, "The proposed merger with Oqory reflects our commitment to develop transformative therapies for patients with cancer. The promising efficacy and favorable safety profile demonstrated by OQY-3258 highlights its potential as a best-in-class anti-TROP2 ADC."
