Revisions for Doxycycline for prostate cancer | Registro Público Cubano de Ensayos Clínicos

Revision of 12 December 2025 - 1:37pm:

Doxycycline for prostate cancer

General information

Section to complete general information about the trial: scientific and public title, protocol identifiers, sponsors and Source(s) of Monetary or Material Support.

Acronym of Public Title:

DOXCAPROST

Scientific title:

New therapeutic scheme for patients with advanced prostate cancer: phase II clinical trial using doxycycline combined with antiandrogen treatment.

Acronym of Scientific Title:

DOXCAPROST

Secondary indentifying numbers:

Not applicable

Issuing authority of the secondary identifying numbers:

Not applicable

Source(s) of monetary or material support:

Mexico Mexican Social Security Institute

Authorization for beginning

Section to complete information about the regulatory approval of clinical trial: regulatory agency name, approval date and reference number in the agency.

Regulatory instance to authorize the initiation of the study:

Only approved by Ethics Committees

Principal investigator

Section to complete information about Email address, telephone number and postal address of the Principal Investigator.

First name:

José

Last name:

Guzman Esquivel

Medical Specialty :

Urology

Affiliation:

Mexican institute of social security, General Hospital of Zone 1

Postal address:

Lapislazuli Avenue No 250, Colonia El Haya

City:

Villa de Alvarez, Colima

Country:

Mexico

Zip Code:

28984

Telephone:

+52-3123163460

Email address:

pepeguzman_esquivel@outlook.com

Clinical sites to participate

Section to complete the data related to the clinical sites involved in the trial: site and responsible investigator for every site.

Countries of recruitment:

Mexico

Clinical sites:

Not Applicable

Recruitment status

Section to complete information about the recruitment status and the date of first enrolment subject

Recruitment status:

Complete

Date of first enrollment:

14/08/2020

Health condition and Intervention

Section to complete information about the primary medical condition(s) or problem(s) studied and, a characteristics of the intervention(s).

Health condition(s) or Problem(s) studied:

Prostate cancer

Health condition(s) code:

Prostatic Neoplasms

Genital Neoplasms, Male

Urogenital Neoplasms

Prostatic Diseases

Genital Diseases, Male

Male Urogenital Diseases

Intervention(s):

Intervention Experimental Group (group A): You will receive doxycycline 100 mg every 24 hours for 6 months, plus its standard treatment, which consists of bicalutamide 50 mg orally per day, and leuproline 22.5 mg in subcutaneous application every three months, in addition to docetaxel according to the oncologist's criteria. The doxycycline dose is less than the maximum previously recommended for chronic treatments such as acne conglobata. The commercial presentation for human use is in 100mg pills, so patients in the experimental group will take 1 pill every 24 hours. Control Group Intervention (group B): You will receive your standard treatment as indicated by current clinical practice (bicalutamide 50mg orally per day, and leuproline 22.5mg in subcutaneous application every three months, in addition to docetaxel according to the oncologist's criteria), plus a bottle of placebo pills that your doctor will provide. monthly in his office with the indication to take 1 pill every 24 hours, for 6 months.

Intervention code:

Doxycycline

Leuprolide

Tablets

Placebos

Administration, Oral

Injections, Subcutaneous

Intervention keyword:

Bicalutamida

Outcomes and Timepoint

Section to complete information about primary and secondary outcomes including. It includes the metric or method of measurement used and, the time point for every outcome.

Primary outcome(s):

Complete response (25% reduction in serum specific prostate antigen). Measuring time: 3 and 6 months.

Key secondary outcomes:

Adverse events (according to the common terminology of criteria for adverse events (CTCAE version 3). Measurement time: every week until month 6. Change in the level of prostate-specific antigen at 6 months of treatment. Quality of life and cognitive impairment were assessed with the EORTC QLQ-PR25 questionnaire and the Mini-Mental State Examination test, respectively, applied at baseline and 6 months after treatment.

Selection criterias

Section to complete information about the inclusion and exclusion criteria for participant selection, including age and gender.

Gender:

Male

Minimum age:

18 years

Maximum age:

85 years

Inclusion criteria:

1. Clinical and histological diagnosis of excised adenocarcinoma, locally advanced and metastatic prostate cancer. 2. Patients who accept, with informed consent, the administration of doxycycline or placebo, in a randomized system

Exclusion criteria:

1. Diagnosis of another primary cancer other than prostate. 2. Alcoholism and / or drug addiction. 3. Allergic to tetracyclines. 4. Gastrointestinal ulcer. 5. Inflammatory bowel disease. 6. Diagnosis of ischemic heart disease. 7. Liver disease. 8. Kidney disease.

Type of population:

Adults

Type of participant:

Patients

Study design

Section to complete information about the characteristics of the study design.

Type study:

Interventional

Purpose:

Treatment

Allocation:

Randomized controlled trial

Masking:

Double Blind

Control group:

Active

Study design:

Parallel

Phase:

2

Target sample size:

40

Contact for public queries

Section to complete information about Email address, telephone number and postal address of the contact who will respond to general queries, including information about current recruitment status

First Name:

José

Last Name:

Guzman Esquivel

Specialty:

Urology

Affiliation:

Mexican Institute of Social Security, General Hospital of Zone 1

Postal Address:

Lapislazuli Avenue No 250, Colonia EL Haya

City:

Villa de Alvarez, Colima

Country:

Mexico

Zip Code:

28984

Telephone:

+52-312 316 3460

Email :

pepeguzman_esquivel@outlook.com

Contact for scientific queries

Section to complete information about Email address, telephone number and postal address of the contact who will respond to scientific queries.

First Name:

IVÁN

Last Name:

DELGADO ENCISO

Specialty:

MOLECULAR BIOLOGY

Affiliation:

Cancerology State Institute, Colima State Health Service

Postal Address:

Avenue Liceo de Varones 401, Colonia La Esperanza

City:

Colima

Country:

Mexico

Zip Code:

28085

Telephone:

+52-3121521435

Email :

ivancoliman@hotmail.com

ivan_delgado_enciso@ucol.mx

Research Ethics Committees

Section to complete the data related to the review ethics committees.

Name of Research Ethics Committees:

Comité de Ética local de Investigación en Salud del H. Gral Zona-MF-Num 1 (CONBIOETICA-06-CEI-001-2017121)

Status of evaluation:

Approved

Status of evaluation date of Ethic Committee:

20/08/2020

Postal address of Ethic Committee :

Av. Lapizlazulli No. 250, Colonia El Haya, Villa de Alvarez, Colima. Mexico

Telephone:

+52 312-316-3460

Email:

luis.deleon@imss.gob.mx

About study completion

Section to complete the data related to the study completion.

Final enrolment number:

32

Study completion date:

01/12/2021

Results Study

Section to complete the data related to the summarized results.

Summary study:

Background/Objectives: Metastatic prostate cancer remains a major clinical challenge, with limited therapeutic options. Doxycycline, a tetracycline antibiotic with anti-inflammatory properties, has shown potential as an adjunctive therapy. This study aimed to evaluate its efficacy in reducing prostate-specific antigen (PSA) levels and improving quality of life in patients receiving standard treatment for metastatic prostate cancer. Methods: This phase II, double-blind, randomized controlled trial included 45 participants (aged 57–81 years) assigned to doxycycline (100 mg daily) or a placebo for six months. The primary outcome was the percentage change in PSA levels at 3 and 6 months. Secondary outcomes included quality of life (EQ-5D-5L), cognitive function (Mini-Mental State Examination), and glucose levels. Additionally, a structure–activity relationship (SAR) analysis was performed through an extensive bibliographic review to identify pharmacophores responsible for doxycycline’s biological activity, particularly its tetracyclic core. The SAR analysis included tetracyclines and derivatives, androgen-targeting agents, and other pharmacologically relevant molecules used in prostate cancer therapy. Statistical analysis was conducted using multivariate logistic regression. Results: At six months, the doxycycline group showed a median PSA reduction of 60% compared to 10% in the placebo group (p = 0.043). A ≥50% reduction in PSA levels was observed in 71.4% of patients receiving doxycycline versus 20.8% in the placebo group (p = 0.001), with an adjusted relative risk of 10.309 (95% CI: 2.359–45.055, p = 0.002). Quality of life improved, with 7.1% of doxycycline-treated patients reporting poor quality of life compared to 42.9% in the placebo group (p = 0.028). A slight improvement in cognitive function was also noted (p = 0.037). SAR analysis suggested that the tetracyclic ring of doxycycline may play a crucial role in its observed biological effects. Conclusions: Doxycycline demonstrates potential as an adjunctive therapy in metastatic prostate cancer by reducing PSA levels and improving quality of life. The SAR analysis supports the hypothesis that its tetracyclic structure may be responsible for its therapeutic effects. Further large-scale trials are warranted to confirm these findings.

Url for Results File:

https://www.mdpi.com/1999-4923/17/4/404

Registration and Update

Section to complete information about the name of Primary Registry, date of registration and the unique ID number assigned by the registry (RPCEC).

Primary registry:

RPCEC

Unique ID number:

RPCEC00000367

Date of Registration in Primary Registry:

11/05/2021

Record Verification Date:

2025/12/12

Next update date:

2026/12/12

Link to the spanish version:

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12 December 2025 - 1:36pm by Gladys		12 December 2025 - 1:37pm by Gladys
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