Dr Van Gorp on PFS Data With TUB-040 in Platinum-Resistant Ovarian Cancer

“This means that not only do we have a high overall response rate, but when [patients] do respond, they stay on the drug for a very long time.”

Toon Van Gorp, MD, PhD, a gynaecological oncologist at the University Hospital Leuven/Leuven Cancer Institute, lead for the Department of Gynaecological Oncology, and chair of the Belgium and Luxembourg Gynaecological Oncology Group, discussed data from the phase 1/2a NAPISTAR 1-01 trial (NCT06303505) evaluating the NaPi2b-targeting antibody-drug conjugate (ADC) TUB-040 in patients with platinum-resistant ovarian cancer (PROC), focusing on progression-free survival (PFS) and duration of response (DOR) findings presented at the 2026 ASCO Annual Meeting.

TUB-040 pairs an Fc-silenced NaPi2b-targeting antibody with an exatecan (topoisomerase 1 inhibitor) payload delivered via a peptide-cleavable linker. Across the overall NAPISTAR 1-01 population of heavily pretreated patients with PROC (n = 67), the agent produced an unconfirmed objective response rate (ORR) of 64.2% (95% CI, 51.5%-75.5%) and a confirmed ORR of 58.2% (95% CI, 45.5%-70.2%). At the April 5, 2026, data cutoff, the median PFS was 11.0 months (95% CI, 7.5-not available [NA]), with 71% and 50% of patients progression free at 6 and 12 months, respectively.

That PFS compares favorably with recently reported phase 3 data in PROC, according to Van Gorp, who noted that the phase 3 KEYNOTE-B96 (NCT05116189), ROSELLA (NCT05257408), and MIRASOL (NCT04209855) trials each produced a median PFS below 8.3 months, calling the NAPISTAR 1-01 result remarkable by comparison. The median DOR was not reached (95% CI, 8.5 months-NA) at a median follow-up of 8.7 months, with 79% and 57% of responders maintaining their response beyond 6 and 12 months, respectively.

Van Gorp said the findings reflect not just a high response rate but responses that persist over time, supporting continued development of TUB-040 in a biomarker-unselected PROC population.