Astra speeds puxita-S into pivotal development

It took AstraZeneca three years to report data from the sole clinical trial of puxitatug samrotecan, but now the group reckons it's found a sufficiently promising patient population to take this anti-B7-H4 ADC straight into phase 3. The pivotal Bluestar-Endometrial01 study, which has just appeared on clinicaltrials.gov, will test puxita-S in endometrial cancer patients who have progressed on platinum chemo and PD-(L)1 blockade, given in no more than two prior therapy lines. Importantly, B7-H4 expression is an enrolment criterion, though the cutoff hasn't been disclosed. Puxita-S's phase 1/2 solid tumour study required B7-H4 expression of at least 25%, but other companies set a higher number. Those phase 1/2 data disappointed at last year's ESMO, but Astra subsequently zeroed in on a 37% ORR from 52 endometrial cancer patients, and first revealed plans to go pivotal in April. The new listing does disclose that a 2.4mg/kg puxita-S dose will be tested – highly relevant given that dose-limiting toxicities were seen at 3.2mg/kg. Astra has sponsored pivotal trials of ADCs including Enhertu, Datroway and sonesitatug vedotin, but Bluestar-Endometrial01 is its first with an in-house developed ADC. The only other anti-B7-H4 ADC in phase 3 is GSK/Hansoh's GSK5733584.

Phase 3 studies of anti-B7-H4 ADCs

Source: OncologyPipeline.