The FDA has granted accelerated approval to dostarlimab, sold as Jemperli, for a specific group of adults with locally advanced rectal cancer. The 19 October decision covers stage II or III disease that is microsatellite instability-high (MSI-H) or mismatch repair deficient (dMMR), as determined by an FDA-authorised test. It is not an approval for every rectal cancer. FDA technical account
The important evidence distinction is between a clinical complete response and proof of lasting benefit. The trial provides response observations; accelerated approval leaves verification of clinical benefit as a continuing requirement.
What AZUR-1 measured
AZUR-1 is an open-label, single-group phase 2 study. Its registry separates the primary response endpoint from longer-term outcomes, including survival. There is no randomised comparison group in this design. Trial registry
The FDA reports 154 treated participants. For clinical complete response sustained for 12 months, usually shortened to cCR12, the assessment method and denominator matter:
| Assessment reported by FDA | Evaluable participants | cCR12 estimate |
|---|---|---|
| Independent central review | 116 | 47% |
| Investigator assessment | 144 | 68% |
These percentages do not refer to identical assessed populations. They must not be averaged, treated as two separate trials or read as response rates among all 154 treated participants. FDA results summary
GSK’s account supplies the corresponding counts: 54 of 116 for central review and 98 of 144 for investigator assessment. Its announcement also places the full congress presentation later in October. It is the sponsor’s account of the same trial, not an independent confirmation. Sponsor results summary
Response is an observation at a defined time
“Clinical complete response” describes the absence of detectable disease on the trial’s clinical assessments. Sustaining that finding for 12 months adds a time requirement; it does not prove that cancer can never return. The registry’s separate longer-term endpoints help explain why response and survival should remain distinct. AZUR-1 endpoints
The same discipline applies to organ preservation. A response assessment cannot, on its own, answer how an individual’s future treatment will unfold. This is a report of the regulatory evidence, not advice to start, stop or substitute treatment.
What accelerated approval leaves to establish
The FDA’s accelerated pathway can use an endpoint reasonably likely to predict clinical benefit, with further study needed to verify that benefit. Continued approval for this indication may depend on confirmatory evidence. Pathway explanation, specific decision
Potential benefit also belongs beside harms. GSK reports serious adverse reactions in 20% of participants and treatment discontinuation for adverse reactions in 3%. These figures describe trial safety observations; they are not an individual risk estimate. Sponsor safety summary
The US decision is a meaningful development for a narrowly defined population. Its interpretation still depends on biomarker eligibility, the assessment method, follow-up and the evidence required after accelerated approval. None of those conditions can be replaced by the single word “response”.