A new drug for endometriosis: How does it work and why is it different?
Endometriosis is one of the most common and underdiagnosed gynaecological disorders. It affects around 1 in 10 women of reproductive age and can cause severe pelvic pain, painful menstruation and fertility problems.
Numerous studies have shown that diagnostic delays can extend for several years, directly affecting patients’ quality of life.
Now, Yselty, a new medication approved by the Spanish Agency of Medicines and Medical Devices (AEMPS), represents a significant advance. It is a new therapeutic option that enables more precise modulation of the hormonal cycle without the need for complete suppression.
It has two main indications in adult women of reproductive age: the treatment of moderate to severe symptoms associated with uterine fibroids and the symptomatic treatment of endometriosis in women who have previously received other treatments without achieving satisfactory results.
This approach paves the way for a more flexible, personalised treatment strategy.
What makes it different from conventional hormonal treatments?
- It does not require complete, continuous suppression of the menstrual cycle.
- It allows more precise control of hormone levels, depending on the dose administered.
- It expands the therapeutic options available for patients who have shown an insufficient response to standard treatments.
This mechanism represents a significant advance in the management of moderate to severe endometriosis, particularly in refractory cases.
Who is the new endometriosis treatment intended for?
In the context of endometriosis, this medication is specifically indicated for adult women of reproductive age:
- With pain associated with endometriosis.
- Who have previously received medical treatment, such as oral contraceptives, progestogens or intrauterine devices (IUDs), among others, and who continue to experience symptoms or show clinical recurrence despite treatment.
It is not considered a first-line treatment but rather an advanced therapeutic option within the management of the disease.
Is it a cure for endometriosis?
Despite it being an advance, this medication does not constitute a definitive cure for endometriosis.
The specific mechanism of action of Yselty, which belongs to the class of oral gonadotropin-releasing hormone (GnRH) receptor antagonists acting at the pituitary level, consists of inhibiting this signalling pathway; thereby reducing the production of LH and FSH, the hormones responsible for stimulating the ovaries to produce oestrogens.
Unlike other treatments, its effect is dose-dependent (available at doses of 100 and 200 mg/day), allowing oestrogen reduction to be modified without causing complete and abrupt hormonal suppression.
This helps reduce the activity of oestrogen-dependent endometriotic lesions while potentially minimising some adverse effects associated with very low oestrogen levels, such as loss of bone mineral density and menopause-like symptoms.
The objectives of this treatment are therefore to:
- Reduce endometriosis-associated pain.
- Improve quality of life.
- Control disease progression.
- Reduce the adverse effects commonly associated with hormonal therapies.
Current research continues to advance towards therapies that target not only hormonal pathways but also inflammation and immune system dysfunction.
What is the current treatment for endometriosis?
To date, treatment has been based primarily on:
- Combined hormonal contraceptives.
- Progestogens.
- GnRH analogues.
- Surgery in selected cases.
All of these approaches share a common objective: to reduce the hormonal stimulation that promotes the growth of endometriotic lesions.
Ryeqo: another therapeutic innovation
Before the arrival of linzagolix, Ryeqo® had also been incorporated into the treatment of endometriosis. It is another oral GnRH antagonist based on a combination of relugolix, oestradiol and norethisterone acetate.
Its mechanism of action consists of reducing ovarian oestrogen production by blocking GnRH receptors while combining this effect with low-dose hormone replacement therapy. This strategy helps control endometriosis-associated pain and reduces the activity of the lesions. It also maintains hormone levels sufficient to reduce adverse effects such as hot flushes, decreased bone mineral density and other symptoms associated with hypooestrogenism.
Its introduction expands the range of available treatment options and reinforces the current trend towards medicine tailored to the needs and characteristics of each patient.
A new approach to endometriosis: towards more personalised treatments
This advance reflects a clear trend in gynaecology: a shift from generalised treatments towards more personalised therapies for patients with endometriosis.
This is the direction in which endometriosis treatment is evolving:
- More precise hormonal treatments.
- Anti-inflammatory therapies.
- Improved early diagnosis.
- Personalised medicine based on each patient profile.
The approval of this new medication represents a significant advance in the treatment of endometriosis, particularly for patients who do not respond to traditional hormonal therapies.
Although it is not a cure, it expands the available therapeutic options and opens the door to a new stage in the management of this chronic disease.
INFORMATION DOCUMENTED BY:
Dr Meritxell Gràcia, Gynaecology Departement, Hospital Clínic Barcelona
