BL-B01D1-307
The first phase 3 win for a bispecific ADC, in triple-negative breast cancer, announced February 2026.
Interim analysis met PFS and OS with statistically significant and clinically meaningful improvements (topline 26 February 2026; full data ASCO 2026). Conducted in China; global trials underway. Parallel positive phase 3 in oesophageal squamous cell carcinoma.
Setting
Previously treated locally advanced or metastatic TNBC: izalontamab brengitecan vs chemotherapy
Phase
Phase 3
Sponsor
SystImmune / BMS
Registry
Headline result
PFS and OS significantly improved at interim analysis (numbers presented ASCO 2026).
Reported
2026
Enrolled
418
Replication
Single Chinese phase 3 with an interim OS analysis; a parallel positive phase 3 in oesophageal squamous cell carcinoma supports the drug, and the global IZABRIGHT-Breast01 trial will test the first-line setting. Not yet replicated outside China.
In plain words
What these results mean for people, not percentages
Progression-free survival (BICR)primarysurrogate endpoint
- Median 8.5 vs 3.1 months with Izalontamab brengitecan compared with Chemotherapy (TPC); about 5.4 months longer for half the group.
- A median is a midpoint: half the people did better than this and half did worse, so it is not a prediction for any one person.
- Put another way, the treated group had about 71 percent lower chance of the event at any given time (hazard ratio 0.29, likely range 0.22 to 0.38).
- This is a surrogate endpoint: it measures the cancer being controlled or absent on scans and tests, which often, but not always, translates into living longer.
Overall survival (interim, median follow-up 11 months)primarysurvival endpoint
- Median 15.9 vs 12.5 months with Izalontamab brengitecan compared with Chemotherapy (TPC); about 3.4 months longer for half the group.
- A median is a midpoint: half the people did better than this and half did worse, so it is not a prediction for any one person.
- Put another way, the treated group had about 40 percent lower chance of the event at any given time (hazard ratio 0.6, likely range 0.42 to 0.85).
- Overall survival counts deaths from any cause, so it is the most direct measure of whether a treatment helps people live longer.
Confirmed objective response rate (BICR)response endpoint
- 51.7 vs 20.5 out of 100 had their tumour shrink with Izalontamab brengitecan compared with Chemotherapy (TPC); 31.2 more per 100.
- Roughly one extra person helped for every 3 treated. That is a rough figure taken from the two percentages, not a guarantee for any one person.
- A response rate counts how many people had their tumours shrink by a set amount; shrinking is encouraging but does not by itself show that people live longer or feel better.
Be careful
- These results apply to the people the trial enrolled: Previously treated locally advanced or metastatic TNBC: izalontamab brengitecan vs chemotherapy. People in a different situation may not see the same effect.
Numbers are from the trial as recorded here; see the source links in the table below. This is orientation, not medical advice: ask your team how closely the trial population matches you.
418 participants enrolled.
Progression-free survival (BICR)primary
HR 0.29 (0.22–0.38) · p <0.0001
Izalontamab brengitecan
8.5 mo
Chemotherapy (TPC)
3.1 mo
Overall survival (interim, median follow-up 11 months)primary
HR 0.6 (0.42–0.85) · p = 0.0019
Izalontamab brengitecan
15.9 mo
Chemotherapy (TPC)
12.5 mo
Confirmed objective response rate (BICR)
Izalontamab brengitecan51.7 of 100
Chemotherapy (TPC)20.5 of 100
| Endpoint | Arm | n | Value | HR (95% CI) | p | Source |
|---|---|---|---|---|---|---|
| Progression-free survival (BICR)primary | Izalontamab brengitecan | 207 | 8.5 months | 0.29 (0.22–0.38) | <0.0001 | link |
| Chemotherapy (TPC) | 211 | 3.1 months | ||||
| Overall survival (interim, median follow-up 11 months)primary | Izalontamab brengitecan | — | 15.9 months | 0.6 (0.42–0.85) | 0.0019 | link |
| Chemotherapy (TPC) | — | 12.5 months | ||||
| Confirmed objective response rate (BICR) | Izalontamab brengitecan | — | 51.7% | — | — | — |
| Chemotherapy (TPC) | — | 20.5% |
Replication
Single Chinese phase 3 with an interim OS analysis; a parallel positive phase 3 in oesophageal squamous cell carcinoma supports the drug, and the global IZABRIGHT-Breast01 trial will test the first-line setting. Not yet replicated outside China.