Custirsen: Designed to Inhibit the Cytoprotective Chaperone Protein ClusterinCustirsen is an experimental drug that is designed to block the production of the protein clusterin, which may play a fundamental role in cancer cell survival and treatment resistance. Clusterin is upregulated in tumor cells in response to treatment interventions such as chemotherapy, hormone ablation and radiation therapy and has been found to be overexpressed in a number of cancers, including prostate, lung, breast and bladder. Increased clusterin production has been linked to faster rates of cancer progression, treatment resistance and shorter survival duration. By inhibiting clusterin, custirsen is designed to alter tumor dynamics, slowing tumor growth and resistance to partner treatments, so that the benefits of therapy, including survival, may be extended.
As part of Phase 1 and Phase 2 clinical trials, custirsen was administered to 294 patients with various types of cancer. The majority of adverse events were mild. The most common adverse events associated with custirsen consisted of flu-like symptoms. The most common serious adverse events (SAE) associated with custirsen were febrile neutropenia, fever, pleural effusion, and dyspnea. Each SAE event was observed in approximately 2%-4% of patients.
Research shows that clusterin contributes to cancer’s ability to resist apoptosis by:
- Inhibiting proapoptotic signaling through interaction with surface proteins (eg, receptors) on stressed cells
- Inhibiting the proapoptotic protein Bax to prevent its activation of the intrinsic pathway through the mitochondria
- Promoting cell survival by enhancing NF-_B transcriptional activity
- Inhibiting endoplasmic reticulum stress and the aggregation of proteins to maintain protein homeostasis
Clinical Trial Results
- Custirsen has been administered to nearly 300 patients with various types of cancer in Phase 1 and Phase 2 clinical trials.
- A broad range of preclinical studies show that custirsen decreases clusterin levels and sensitizes tumor cells to standard chemotherapeutic drugs.
- Custirsen’s ability to enhance the effects of standard therapies has been evaluated in five Phase 2 clinical trials. The Phase 2 results in prostate cancer suggest there may be an overall survival benefit as well as an improvement in durable pain palliation in prostate cancer. Phase 2 results in lung cancer suggest survival outcomes compared favorably with previously published data of similar regimens.
Learn more about Phase 1 Clinical Trial Results.
Learn more about Phase 2 Clinical Trial Results.
Learn more about Phase 3 Clinical Trial Results.
Clinical Development Program
AFFINITY: Phase 3 Trial of Custirsen in Second-Line Metastatic Castrate-Resistant Prostate Cancer (CRPC)
AFFINITY is a company-sponsored, randomized Phase 3 trial evaluating whether custirsen, when combined with the second-line chemotherapy, Jevtana® (cabazitaxel), has the potential to improve survival outcomes for metastatic CRPC patients who have progressed following treatment with docetaxel. Patients were randomly selected to receive Jevtana plus prednisone with or without custirsen therapy, and are eligible for the trial regardless of prior therapy with androgen targeting treatments such as Zytiga® (abiraterone acetate) or Xtandi® (enzalutamide).
The trial enrolled 634 men with metastatic CRPC and was conducted throughout North America, Europe, Russia and Australia.
•Received Fast Track Designation
Overall survival results in ITT population announced in August 2016.
Phase 3 Clinical Trial in Advanced or Metastatic Non-Small Cell Lung Cancer (NSCLC)
ENSPIRIT is a company-sponsored Phase 3 trial evaluating the potential of custirsen to improve survival outcomes in patients with advanced or metastatic NSCLC who have progressed after initial chemotherapy treatment has failed. Patients were randomly selected to receive a second-line standard of care, docetaxel treatment, with or without custirsen therapy.
The trial enrolled 664 patients with advanced or metastatic NSCLC and was conducted internationally.
•Received Fast Track Designation
Overall survival results announced in October 2016.Learn more
Jevtana® is a registered trademark of sanofi-aventis.
Zytiga® is a registered trademark of Johnson & Johnson.
Xtandi® is a registered trademark of Astellas Pharma Inc.
Kirsten Anderson, Vice President, Clinical Operations
“We’re working to better understand the role that clusterin plays in enabling cell survival. By inhibiting this cytoprotective chaperone protein, custirsen may enable therapeutic interventions such as chemotherapy, hormone ablation and radiation therapy to work better, potentially increasing survival in prostate and lung cancers.”