Fluoxetine treatment to modify immune cells in colorectal cancer patients before surgery

Repurposing Drugs as Immunotherapeutic Agents: Changes in Colorectal Tumor Immune Cells After Targeting Serotonin

Phase 1 Interventional Jonsson Comprehensive Cancer Center · NCT06225011

This study is testing if taking fluoxetine for 10 days can change the immune cells in colorectal cancer patients before their surgery to see if it helps slow down tumor growth.

Quick facts

PhasePhase 1
Study typeInterventional
Enrollment10 (estimated)
Ages18 Years and up
SexAll
SponsorJonsson Comprehensive Cancer Center Academic / other
Drugs / interventionschemotherapy
Locations1 site (Los Angeles, California)
Trial IDNCT06225011 on ClinicalTrials.gov

What this trial studies

This phase I trial investigates the effects of fluoxetine, a selective serotonin reuptake inhibitor, on tumor immune cell composition in patients with colorectal adenocarcinoma prior to surgery. Participants will take fluoxetine orally once daily for 10 days, aiming to alter the immune environment of the tumor and potentially inhibit tumor growth and spread. The primary objective is to evaluate changes in immune cell activity and composition resulting from the treatment.

Who should consider this trial

Good fit: Ideal candidates include adults aged 18 and older with untreated colorectal adenocarcinoma who do not require neoadjuvant therapy.

Not a fit: Patients with advanced colorectal cancer requiring immediate treatment or those with significant comorbidities may not benefit from this study.

Why it matters

Potential benefit: If successful, this approach could enhance the immune response against colorectal cancer, potentially improving surgical outcomes.

How similar studies have performed: While the use of SSRIs in cancer treatment is an emerging area, similar studies have shown promise in modifying immune responses, though this specific approach is novel.

Eligibility criteria

Show full inclusion / exclusion criteria
Inclusion Criteria:

* Male or female ≥ 18 years of age at visit 1
* Previously untreated cytologically or histologically confirmed colorectal adenocarcinoma that will not need neoadjuvant therapy
* Written informed consent (and assent when applicable) obtained from subject or subject's legal representative and ability for subject to comply with the requirements of the study
* World Health Organization (WHO) Eastern Cooperative Oncology Group (ECOG) performance status 0-2
* Absolute neutrophil count (ANC) ≥ 1.5x10\^9/L
* Platelets ≥ 100x10\^9/L
* Hemoglobin ≥ 9 g/dL
* Serum creatinine (sCr) ≤ 1.5 x upper limit of normal (ULN)
* Creatinine clearance (Ccr) ≥ 40 mL/min (as calculated by Modified Cockcroft-Gault formula)
* Serum total bilirubin ≤ 1.5 x ULN
* Aspartate aminotransferase (AST)(serum glutamic-oxaloacetic transaminase \[SGOT\]) / alanine aminotransferase (ALT)(serum glutamate pyruvate transaminase \[SGPT\]) ≤ 2.5 x ULN
* Baseline corrected QT (QTc) within normal limits per the Bazett formula. Any electrocardiogram (EKG) done prior to consent is acceptable for baseline QTc monitoring.

  * Normal QTc ranges from 350-450 ms for adult men and from 360-460 ms for adult women

Exclusion Criteria:

* Presence of a condition or abnormality that in the opinion of the investigator would compromise the safety of the participant or the quality of the data
* A diagnosis of metastatic colorectal adenocarcinoma
* Individuals who have received neoadjuvant chemotherapy prior to the planned colon cancer resection
* Individuals with absolute or relative contraindications to fluoxetine

  * Baseline prolonged QTc
  * Concurrently taking tamoxifen, pimozide, or thioridazine
* Individuals using other SSRIs, serotonin and norepinephrine reuptake inhibitors (SNRIs), monoamine oxidase inhibitors (MAOIs), lithium or other antidepressants at time of initial biopsy
* Currently active second primary malignancy or history of malignancy less than 5 years prior to the time of study eligibility (Patients with history of skin cancers excluding melanoma will be eligible for participation)

Where this trial is running

Los Angeles, California

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.
Conditions Colorectal Adenocarcinoma
Last reviewed 2026-06-13 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.