# IMPACT (sipuleucel-T)

Source: https://onco.cc/trials/impact-sipuleucel-t/  
OnCo record `impact-sipuleucel-t` (Trial). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

The first cancer vaccine ever approved anywhere. It extended life by about four months without shrinking a single tumour, and the company that made it went bankrupt.

## Summary

IMPACT randomised 512 men with metastatic castration-resistant prostate cancer 2:1 to sipuleucel-T (341) or placebo (171), given intravenously every 2 weeks for three infusions. The primary endpoint was overall survival, analysed by a stratified Cox model adjusted for baseline PSA and lactate dehydrogenase.

Sipuleucel-T reduced the risk of death by 22 percent, hazard ratio 0.78 (95 percent confidence interval 0.61 to 0.98, p=0.03), a 4.1-month gain in median survival (25.8 against 21.7 months). Thirty-six-month survival was 31.7 against 23.0 percent. The result held in an unadjusted model (0.77, 0.61 to 0.97, p=0.02) and after adjusting for later docetaxel use (0.78, 0.62 to 0.98, p=0.03).

The time to objective disease progression was the same in both groups. Nothing shrank. That dissociation, longer life without tumour response, is the finding that taught oncology that immunotherapy does not have to shrink a tumour to work, and it was the reason the field developed immune-related response criteria before checkpoint inhibitors arrived. Chills, fever and headache were the characteristic adverse events.

The commercial story is the cautionary one. The product required leukapheresis and a manufacturing turnaround for each man, was very expensive, and never sold in the volumes needed. Dendreon filed for bankruptcy in 2014. In England NICE TA332 on sipuleucel-T has been withdrawn because the marketing authorisation was withdrawn, so it is not available at all.

## Fields

- Kind: Trial
- Status: positive
- Last checked: 2026-09-25
- Also known as: IMPACT; D9902B; Immunotherapy for Prostate Adenocarcinoma Treatment
- Registry id: NCT00065442
- Phase: 3
- Setting: Metastatic castration-resistant prostate cancer: sipuleucel-T, an autologous cellular immunotherapy made from the man's own antigen-presenting cells loaded with a prostatic acid phosphatase fusion protein, against placebo, three infusions two weeks apart, randomised 2:1, with overall survival as the primary endpoint
- Sponsor: Dendreon
- Enrolled: 512
- Result: Median overall survival 25.8 against 21.7 months (hazard ratio 0.78, 95 percent confidence interval 0.61 to 0.98, p=0.03) with no difference in time to objective disease progression.
- Outcomes: Overall survival (median): Sipuleucel-T 25.8 months vs Placebo 21.7 months, HR 0.78; Survival at 36 months: Sipuleucel-T 31.7% vs Placebo 23%
- Replication: No independent randomised replication; PROSTVAC, the other prostate cancer vaccine taken to phase 3, failed outright in PROSPECT.

## Sources

- ClinicalTrials.gov NCT00065442: https://clinicaltrials.gov/study/NCT00065442
- IMPACT (New England Journal of Medicine 2010): https://doi.org/10.1056/NEJMoa1001294
- NICE TA332: sipuleucel-T for asymptomatic or minimally symptomatic metastatic hormone-relapsed prostate cancer, guidance withdrawn because the marketing authorisation was withdrawn: https://www.nice.org.uk/guidance/ta332

## Connected records

- cancers: [Metastatic castration-resistant prostate cancer](https://onco.cc/cancers/prostate-mcrpc/), [Prostate cancer](https://onco.cc/cancers/prostate/)
- technologies: [Dendritic cell vaccines](https://onco.cc/technologies/dendritic-cell-vaccines/), [Immune checkpoint inhibitors](https://onco.cc/technologies/checkpoint-inhibitor/)
- drugs: [PROSTVAC](https://onco.cc/drugs/prostvac/), [Sipuleucel-T](https://onco.cc/drugs/sipuleucel-t/)
- companies: [Dendreon](https://onco.cc/companies/dendreon/)
- terms: [Castration-resistant prostate cancer (CRPC)](https://onco.cc/terms/castration-resistance/)
- trials: [CA184-043](https://onco.cc/trials/ca184-043-ipilimumab/), [PROSPECT](https://onco.cc/trials/prospect-prostvac/)

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