# Custirsen

Source: https://onco.cc/drugs/custirsen/  
OnCo record `custirsen` (Treatment). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

A drug designed to switch off a protein that helps cancer cells survive chemotherapy. Two large trials found it added nothing.

## Summary

Clusterin is a chaperone protein that rises after apoptotic stress, including chemotherapy, and is associated with treatment resistance. Custirsen is a second-generation antisense oligonucleotide that blocks its production, and the hypothesis was that it would re-sensitise prostate cancer to taxanes.

A randomised phase 2 trial (CUOG P-06c, 42 men) reported encouraging pain responses and a correlation between low serum clusterin during treatment and survival, which was enough to justify two phase 3 trials. Both failed. SYNERGY added custirsen to first-line docetaxel in 1,022 men and found median survival 23.4 against 22.0 months, hazard ratio 0.93 (95 percent confidence interval 0.79 to 1.10, p=0.415). AFFINITY added it to cabazitaxel after docetaxel in 635 men and found 14.1 against 13.4 months, hazard ratio 0.95 (0.80 to 1.12, p=0.53), with no benefit in the prespecified poor-prognosis subgroup either.

OncoGenex, which developed it, is now Achieve Life Sciences and no longer works on cancer. The drug is a clean example of a biomarker association, serum clusterin and survival, that did not survive as a therapeutic target.

## Fields

- Kind: Treatment
- Status: withdrawn
- Last checked: 2026-09-25
- Also known as: OGX-011; TV-1011
- Code: OGX-011
- Modality: antisense oligonucleotide
- Mechanism: Second-generation antisense oligonucleotide that inhibits production of the chaperone protein clusterin.

## Sources

- SYNERGY (Lancet Oncology 2017): https://doi.org/10.1016/S1470-2045(17)30168-7
- AFFINITY (Lancet Oncology 2017): https://doi.org/10.1016/S1470-2045(17)30605-8

## Connected records

- cancers: [Metastatic castration-resistant prostate cancer](https://onco.cc/cancers/prostate-mcrpc/), [Prostate cancer](https://onco.cc/cancers/prostate/)
- technologies: [Oligonucleotide therapeutics](https://onco.cc/technologies/antisense-sirna/)
- companies: [Achieve Life Sciences (formerly OncoGenex)](https://onco.cc/companies/achieve-life-sciences/)
- terms: [Castration-resistant prostate cancer (CRPC)](https://onco.cc/terms/castration-resistance/)
- trials: [AFFINITY](https://onco.cc/trials/affinity-custirsen/), [SYNERGY](https://onco.cc/trials/synergy-custirsen/)

---
JSON: https://onco.cc/api/v1/entities/custirsen.json