Photo courtesy of GSK
Eltrombopag (Promacta)
The US Food and Drug Administration (FDA) has granted breakthrough therapy designation to eltrombopag (Promacta®) for use in combination with standard immunosuppressive therapy as first-line treatment for patients with severe aplastic anemia (SAA).
Novartis plans to submit an application to the FDA for this indication later this year.
Eltrombopag is already FDA-approved to treat SAA patients who have had an insufficient response to immunosuppressive therapy.
The drug is also approved to treat patients with chronic immune thrombocytopenia who have had an insufficient response to corticosteroids, immunoglobulins, or splenectomy.
And eltrombopag is approved to treat thrombocytopenia in patients with chronic hepatitis C to allow for the initiation and maintenance of interferon-based therapy.
Trial data
The breakthrough designation for eltrombopag as first-line treatment in SAA is supported by data from a phase 1/2 trial, which were published in NEJM in April 2017.
The trial included 92 patients with previously untreated SAA. They received immunosuppressive therapy and eltrombopag in 3 different cohorts.
Patients in cohort 1 received eltrombopag from day 14 to 6 months. Patients in cohort 2 received the drug from day 14 to 3 months. And patients in cohort 3 received eltrombopag from day 1 to 6 months.
At 6 months, the overall response rate was 80% in cohort 1, 87% in cohort 2, and 94% in cohort 3. The rate of complete response at 6 months was 33%, 26%, and 58%, respectively.
At a median follow-up of 2 years, the overall survival rate was 97%.
Seven patients briefly stopped taking eltrombopag during the first 2 weeks due to transient elevations in liver-enzyme levels.
There were 2 severe adverse events that were related to eltrombopag and resulted in patients stopping the drug. These were a grade 2 and grade 3 cutaneous eruption.
About breakthrough designation
The FDA’s breakthrough designation is intended to expedite the development and review of new treatments for serious or life-threatening conditions.
The designation entitles the company developing a therapy to more intensive FDA guidance on an efficient and accelerated development program, as well as eligibility for other actions to expedite FDA review, such as rolling submission and priority review.
To earn breakthrough designation, a treatment must show encouraging early clinical results demonstrating substantial improvement over available therapies with regard to a clinically significant endpoint, or it must fulfill an unmet need.
