Breakthrough in Male Infertility: Can Clomiphene Boost Sperm Count and Natural Conception? Results from the CONCRETE Double-Blind Trial

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* The findings will be published in medical journals and international conferences. The results will be shared with the NHS repurposing programme to review Clomiphene licence. We devised a PPIE strategy, lay communication strategy, and established strong links with relevant charities to promote the voice of lay men with infertility.






Plain English Summary:

Background


Male factor infertility defined by abnormal semen parameters affects >50% of infertile couples. In most cases no clear cause can be identified for (idiopathic), which may be associated with a mild reduction in Testosterone (secondary hypogonadism). While a common health condition, effective medical treatments for men with hypogonadism or idiopathic male infertility remain limited with an over reliance on using expensive and invasive assisted reproductive technology treatments. Clomiphene is a selective oestrogen receptor modulator that could stimulate testosterone secretion from the testes and boost spermatogenesis. Data from small randomised trials and observational studies suggest some benefit of using it to improve semen parameters in affected men. However, evidence of its efficacy and safety for use in this cohort remains heterogenous due to poor study quality.


Research question

What is the efficacy and safety of clomiphene as a treatment for men with secondary hypogonadism or idiopathic male infertility to improve semen parameters and reproductive outcomes compared to placebo.


Aims and objectives

To evaluate the efficacy and safety of clomiphene as a treatment for men with secondary hypogonadism or idiopathic male infertility.


Objectives

-To determine the efficacy of clomiphene in improving semen parameters in this group of men.

-To determine the efficacy of clomiphene in improving clinical, reproductive and pregnancy outcomes in this group of men

-To determine the safety of clomiphene as a treatment for men with secondary hypogonadism or idiopathic male infertility

-To explore the feasibility and acceptability of using Clomiphene as a primary treatment in this group of men



Methods

A multi-centre two-arm parallel group double-blind placebo controlled randomized trial with an internal pilot and qualitative process evaluation. Men who meet the eligibility criteria from five NHS fertility clinics will be randomized in a 1:1 ratio to either Clomiphene (25mg/day) or identical placebo for 12 months. Both groups will receive standard lifestyle advice as per national guidelines. We will primarily report on change in sperm concentration at 6 months in addition to other semen parameters, biochemical, reproductive, pregnancy, clinical, and quality of life outcomes. Couples seeking to start any assisted conception treatment during the trial will be enabled without delay. An increase of 5 million/ml in sperm concentration can significantly increase the chances of spontaneous conception in men with oligozoospermia. To detect a 5 million/ml improvement in sperm concentration between groups, assuming a 0.5 correlation coefficient and a SD of 10, we need 160 participants to achieve 90% power, and 5% type-1 error rate and allowing 20% loss to follow-up.


Timelines for delivery

We forecast 48 months to execute the trial including: trial set up (Months 1-9), recruitment and intervention delivery (Months 9-21), follow-up (Months 21-33), site close down and capturing pregnancy outcomes (Months 33-42), and statistical analysis and dissemination (Months 42-48).


Anticipated impact and dissemination

The findings will be published in medical journals and international conferences. The results will be shared with the NHS repurposing programme to review Clomiphene licence. We devised a PPIE strategy, lay communication strategy, and established strong links with relevant charities to promote the voice of lay men with infertility.




Chief Investigator(s):
Dr Bassel H.Al WattarORCID logo

Joint Lead Applicant:
Professor Nick FreemantleORCID logo

Co-investigators:
Dr Dimitri KalleasORCID logo , Dr Hakim-Moulay DehbiORCID logo , Dr Vasanti JadvaORCID logo , Miss Pippa sangsterORCID logo , Mr Kevin McElenyORCID logo , Mr Patrick GordonORCID logo , Ms Eleni AnastasiadisORCID logo , Professor Allan PaceyORCID logo

Award:
£2,118,021.17

Programme:
Efficacy and Mechanism Evaluation

Health Category(s):
Reproductive Health and Childbirth

Research Activity(s):
6.1 Pharmaceuticals

Start Date:
March 2025

End Date:
February 2029

Contracting Organisation:
University College London

Research Call:
EME Programme researcher-led

Programme Stream:
Researcher Led

Funding Stream:
EME Researcher Led
 
 

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Scientific Reference

Lakshman KM, Kaplan B, Travison TG, Basaria S, Knapp PE, Singh AB, LaValley MP, Mazer NA, Bhasin S. The effects of injected testosterone dose and age on the conversion of testosterone to estradiol and dihydrotestosterone in young and older men. J Clin Endocrinol Metab. 2010 Aug;95(8):3955-64.

DOI: 10.1210/jc.2010-0102 | PMID: 20534765 | PMCID: PMC2913038

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