A new class of targeted therapy is showing striking results for one of oncology’s most difficult-to-treat populations. At ASCO 2026, results from the NAPISTAR 1-01 trial reported that the antibody drug conjugate (ADC) TUB-040 had a confirmed overall response rate (cORR) of 61% in patients with platinum-resistant ovarian cancer (PROC), a population where treatment options have historically been limited. A cORR is the ratio of patients whose cancer shrinks or disappears after treatment, with imaging verifying the reduction at least four weeks later.
The 61% cORR, including two confirmed complete responses at optimal dose levels of 1.67–3.3 mg/kg, represents a meaningful signal in a space where most therapies fall short.
The data becomes even more compelling when you look at durability. The trial reported a median progression-free survival (PFS) of 11 months, more than double the roughly five-month standard-of-care benchmark for platinum-resistant disease.
TUB-040 is an ADC that targets NaPi2b, a sodium-phosphate transporter protein highly expressed on ovarian tumor cells. That biological specificity is central to why this approach works.
The science of stability: How TUB-040 targets tumor cells
What sets TUB-040 apart from earlier ADC attempts is the engineering precision behind how the drug reaches tumor cells intact. At the core of this NaPi2b ADC is P5 conjugation technology, a proprietary approach developed by the pharmaceutical company Tubulis that produces a uniform drug-to-antibody ratio (DAR) of 8. That uniformity matters: inconsistent DAR values in older ADCs often caused premature payload release, flooding the bloodstream with the chemotherapy agent (in this case, exatecan) before it reached its target. The site-specific linker design keeps the topoisomerase-I inhibitor payload stable in circulation and releases it directly at the tumor site.
NAPISTAR 1-01 (NCT06303505) is a First-in-Human Phase I/IIa study evaluating TUB-040’s safety, pharmacokinetics, and early efficacy, making the ASCO 2026 ovarian cancer news around this trial especially significant for the field.
Accessing the future: clinical trial eligibility and next steps
The NAPISTAR 1-01 trial represents one of the most promising advances in ADC ovarian cancer research in years and it’s still enrolling. Eligible patients include those with platinum-resistant ovarian high-grade serous carcinoma (PROC) and relapsed/refractory adenocarcinoma non-small cell lung cancer. The FDA has also granted Fast Track Designation to TUB-040 for platinum-resistant ovarian cancer, a designation that can meaningfully accelerate the path toward broader availability.
For patients with platinum-resistant disease, knowing whether you qualify for a trial like this could change your options.
If you’ve been exploring treatment options for platinum-resistant disease, you don’t have to navigate eligibility alone. Join the Outcomes4Me community to connect with other patients who share your diagnosis.
Next steps for patients:
Watch Outcomes4Me’s recent webinar with Dr. Beth Y. Karlan, a gynecologic oncologist at UCLA Jonsson Comprehensive Cancer Center. The webinar explores the latest breakthroughs in ovarian cancer in 2026.
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