The European Hematology Association (EHA) held its first hybrid meeting since the start of the pandemic. The in-person meeting took place June 9-12, 2022, in Vienna, Austria. The EHA 2022 Congress provided an opportunity for expert knowledge and experience gained worldwide to come together in one space. Several cutting-edge posters and oral presentations were presented with a focus on immune thrombocytopenia (ITP). The following summaries are from three abstracts presented at EHA.
Preliminary Analysis of the TAPER Trial In ITP patients: Maintenance Following Eltrombopag Use
In this study, investigators looked at the likelihood that adult ITP patients (over 18 years of age) would achieve and maintain a stable platelet count following tapering and discontinuation of treatment with eltrombopag (Promacta®/Revolade®), a thrombopoietin receptor agonist (TPO-RA). Participants received eltrombopag if they had a platelet count less than 30,000 platelets per microliter of blood and had persistent (ITP for 3-12 months) or chronic (ITP for over 12 months) disease that was resistant to, or dependant on, traditional first-line therapies such as corticosteroids. The primary outcome of the TAPER was attained if ITP participants were able to achieve a complete response (platelet count above 100,000) and then were able to maintain a platelet count above 70,000 for at least two months and a platelet count above 30,000 with no bleeding events requiring rescue therapy following tapering or discontinuation of the treatment within a year.
There were 105 ITP participants enrolled in the study; most participants were female, in their mid-forties, and most received the drug for an average of five and half months before discontinuing or tapering treatment. Eighty-five of the 105 participants (85%) achieved a complete response and 65 (62%) were able to maintain a platelet count above 70,000 for at least two months after achieving a complete response. After one year, almost one-third of participants had maintained a platelet count above 30,000 without requiring additional treatment during tapering or after being taken off eltrombopag.
Eltrombopag induced a sustained rise in platelet count during tapering or following discontinuation in many adult ITP patients, including some who had only received the drug for a short period of time and some who were resistant to corticosteroids.
Comments from PDSA’s Medical Advisors:
This study affirms the observation made by several groups that, with time, some patients can maintain a stable platelet count off therapy. This is consistent with long-term responses to corticosteroids and rituximab and may indicate that a new equilibrium between platelet destruction and production develops in some individuals with ITP. It will be important to determine how frequently and how long these responses are maintained with longer follow-up. Knowing which patient is likely to have a successful taper and how long do they need to take the treatment before discontinuing is important. A biomarker would be very helpful here but all this needs to be determined in future studies.
Long-Term Follow-Up with Rilzabrutinib in ITP Patients
In this study, the investigators report on the results of a long-term extension (LTE) trial of Rilzabrutinib, an oral bruton tyrosine kinase (BTK) inhibitor used to treat adults with ITP that works by blocking destruction of antibody-coated platelets and possibly reducing antibody production. Results of its phase 3 study were recently published in the New England Journal of Medicine. The LTE follows previous work showing that Rilzabrutinib created a rapid and stable platelet count response in about 40% of ITP patients with long-standing disease who had received several ITP treatments in the past. Participants who were invited into the LTE had platelet counts above 50,000 for more than half of the follow-up visits within an eight-week period while receiving the study drug.
To date, only 16 participants were enrolled in the LTE trial out of the 45 who participated in the initial investigation; 11 of whom continue to be followed. Most participants in the LTE received Rilzabrutinib in combination with another drug, and one patient required rescue treatment. The average platelet count was 87,000 (68,000 among those receiving the drug as a monotherapy), which was maintained at the six-month check-in. Three participants experienced treatment-related adverse events, such as a respiratory tract infection. Six participants experienced a bleeding event, not related to the treatment (none of which were serious).
Comments from PDSA’s Medical Advisors:
This preliminary communication shows that most participants with ITP who responded to Rilzabrutinib were able to maintain a response for six months without untoward toxicity. Clearly, larger, and longer-term efficacy and safety data will be needed to understand how this new form of treatment is best used to treat ITP e.g., in which patients and at what point in the trajectory of their ITP.
PDSA also presented an abstract at the EHA meeting this year detailing results from our COVID-19 & ITP survey. If you are interested in reading the published abstract, please use the link below: