Sanofi breaks new ground for BTK drugs with ITP approval

Sanofi's BTK inhibitor Wayrilz has become the first drug in the class to be approved by the FDA for immune thrombocytopenia (ITP), a rare autoimmune blood disorder.

Wayrilz (rilzabrutinib) has been cleared by the US regulator for adults with persistent or chronic ITP who have had an insufficient response to a previous treatment.

In ITP, the immune system attacks blood platelets, leading to symptoms like easy bruising and bleeding problems. Many people living with ITP cycle through multiple therapies, unable to achieve long-term disease control, so there is a pressing need for new treatment options.

Sanofi picked up the approval on the strength of the LUNA 3 phase 3 study, in which Wayrilz met the primary and secondary endpoints, showing a positive impact on sustained platelet counts and other ITP symptoms.

After 24 weeks of treatment, 23% of patients treated with the BTK inhibitor had achieved a durable platelet response – defined as platelet counts at or above 50,000/μL for more than eight out of the last 12 platelet measurement visits – versus 0% of those on placebo.

Wayrilz-treated patients also reported an overall 10.6-point improvement across nine health-related quality of life measures, compared to a 2.3-point increase in the placebo arm, on an ITP patient questionnaire.

The US isn't the first to approve Wayrilz – previously described by Sanofi as a pipeline in a pill – as the drug was previously given the go-ahead in the United Arab Emirates (UAE). It is also under regulatory review in Europe and China.

Sanofi's head of specialty care, Brian Foard, said that the drug has the potential to become the treatment of choice for ITYP patients who have not responded to other drugs as its "differentiated mechanism […] addresses the key drivers" of the disease.

Its approval is the second bit of good news for ITP patients in a matter of weeks, coming after Novartis reported positive results in the phase 3 VAYHIT2 trial of its anti-BLyS/BAFF antibody ianalumab in ITP patients previously treated with corticosteroids, a go-to treatment for the rare disease. Novartis is hoping to be in a position to file for approval of ianalumab for ITP in 2027.

Other drugs coming that are being tested in clinical trials for ITP, meanwhile, include Johnson & Johnson and Genmab's anti-CD38 antibody Darzalex (daratumumab), Argenx's FcRn blocker Vyvgart (efgartigimod), Novartis' oral factor B inhibitor Fabhalta (iptacopan), and Sanofi's anti-C1s antibody Enjaymo (sutimlimab) – suggesting the category could get increasingly crowded.

Sanofi acquired Wayrilz as part of its $3.7 billion takeover of Principia Biopharma in 2020, and had some early setbacks with the programme, including failed clinical trials in atopic dermatitis and pemphigus vulgaris.

It remains in clinical development for other rare immune-mediated diseases, notably warm autoimmune haemolytic anaemia (wAIHA), IgG4-related disease (IgG4-RD), and sickle cell disease (SCD).

Sanofi said it would launch Wayrilz in the US later this month with a list price of $17,500 for a month's supply, according to Reuters, which cited analysts at Leerink as putting a peak sales estimate of $2 billion a year for the new product.