P-581 Optimizing efficiency and enhancing patient convenience in DuoStim cycles: A study exploring the continuous application of corifollitropin alpha
Authors: Castillo J  C , Martinez-moya M , Moral P , Fuentes A , Ortiz J , Abellan E , Bernabeu A , Bernabeu R 
Published: July 2024

Abstract

Study question
Corifollitropin alfa in DuoStim cycles: is weekly continuous dosing a viable alternative to daily FSH administration for comparable oocyte yield?

Summary answer
Employing corifollitropin alfa on a weekly basis throughout a DuoStim cycle achieves comparable oocyte numbers to daily FSH while significantly reducing the number of injections.

What is known already
The DuoStim protocol is frequently employed in patients with poor response or low ovarian reserve. However, its utilization has recently been proposed in patients who require elective oocyte/embryo freezing with the aim of maximizing the number of gametes/embryos obtained in a menstrual cycle. While its popularity is growing, the prolonged stimulation period involves the administration of a high number of injectable medications adding to the treatment burden.

Study design, size, duration
A non-inferiority, paired-matched study was planned with a minimum sample size of 13 patients per group, based on a tolerated difference of ± 1 oocyte, SD: 1, 80% power and type 1 error: 5%. Study group (n = 30): patients undergoing DuoStim from November 2022–December 2023. The control group (n = 30) was selected from patients undergoing DuoStim in years 2021-2022 following a standard daily-FSH administration. Controls were 1-to-1 matched based on AMH (±0.4 pmol/l) and age.

Participants/materials, setting, methods
The study group received consecutive injections of 150µg corifollitropin alfa every eight days, along with uninterrupted oral administration of natural progesterone 200 mg/day (LH surge prevention) throughout the follicular and luteal phases. The control group employed a daily-FSH/flexible GnRH-antagonist protocol. GnRH-agonist trigger was used in the follicular phase, whereas either hCGr and/or GnRH-agonist triggering was allowed in the luteal phase.

Main results and the role of chance
Baseline characteristics: age (years), AMH (pmol/l), and BMI (Kg/m2) were comparable between control vs study group (39.7vs40.3, 6.1vs6.1, 24.4vs23.9; p0.05, p0.5 and p0.9, respectively). In terms of the primary objective: total COCs and MII yield (follicular + luteal phase); the standard daily-FSH protocol vs study group achieved a similar total oocyte and MII yield (10.9±5.5 vs 10.4±7.0, p0.6 and 8.7±4.8 vs 7.8±5.6, p0.4, respectively). Additionally, all secondary outcomes (fertilisation rates, number of blastocysts, days of stimulation and gonadotrophin cost) showed no significant differences between the groups. Notably, the study group experienced a remarkable reduction in the number of injections needed to complete a DuoStim cycle [3.8±1.1 vs 30.9±12.9, p &lt; 0.001; MD -27.1±12.5, (95%CI, -49 to -8)].

Limitations, reasons for caution
The secondary outcomes revealed comparable fertilisation rates and blastocyst numbers between the two groups. Nevertheless, it is important to interpret the laboratory results beyond oocyte collection cautiously, considering the smaller sample size (n = 23/group). Larger participant cohorts are necessary to validate these findings and mitigate the risk of type II errors.

Wider implications of the findings
This protocol involving long-acting FSH in combination with natural progesterone offers a viable alternative for patients undergoing DuoStim. It enables comparable results in terms of egg retrieval while minimizing the need for injectables, without increasing the treatment duration or costs. Consequently, it alleviates emotional and therapeutic burdens experienced by patients.

Trial registration number
NCT05815719