Summary
The oral medication avatrombopag proved highly effective against chemotherapy-induced thrombocytopenia (CIT) in a phase 2 clinical trial of patients with gastrointestinal cancers.
CIT is a major burden in cancer treatment and can cause treatment delays that significantly impact patients’ outcomes.
The senior author of the study is Sylvester’s chief of the classical hematology service, Gerald Soff, M.D., who will present the results at the 2026 American Society of Clinical Oncology meeting.
Chemotherapy can be a razor’s edge kind of treatment.
The medications’ ability to kill cancer cells often blurs into toxicity that affects healthy tissues as well. If these toxic side effects are strong enough, they can lead to delays in necessary treatment, giving the cancer time to grow and even acquire resistance to chemotherapy.
One such common side effect of chemotherapy is low blood platelet counts, also called chemotherapy-induced thrombocytopenia (CIT). Chemotherapy suppresses all our blood cells: red blood cells, white blood cells and platelets. Until now, physicians have had effective treatments to overcome low red and white blood cells, but not low platelets. Platelets are a type of blood cell that helps us form clots after injuries. Patients with low platelets are at risk of excessive, life-threatening bleeding after even minor injuries.
Results from a clinical trial led by researchers at Sylvester Comprehensive Cancer Center, part of the University of Miami Miller School of Medicine, and Massachusetts General Hospital point to a potential new treatment for CIT. The oral medication avatrombopag is a type of thrombopoietin receptor agonist. This medication is FDA-approved to treat thrombocytopenia in patients with liver disease, but its effectiveness for CIT remained unclear until now.
Gerald Soff, M.D., chief of classical hematology at Sylvester, led a phase 2 clinical trial of avatrombopag, with a goal to treat 40 patients with gastrointestinal cancers who were experiencing ongoing CIT. The drug proved so effective, however, that Dr. Soff and his colleagues were able to stop the trial at their interim analysis of 23 patients. Dr. Soff will present these results at the 2026 American Society of Clinical Oncology meeting in Chicago.
Preventing Treatment Delays Improves Cancer Outcomes
The trial enrolled patients with gastrointestinal cancers who had persistent CIT, those who were unlikely to recover from low platelets on their own in the time between chemotherapy cycles. Most patients will have a dip in platelet numbers following chemotherapy, but many of them will bounce back without needing treatment or to delay the next cycle. Those with persistent CIT often can’t receive the next chemotherapy dose as scheduled. It would need to be either delayed or reduced in amount. And patients who have delayed or reduced chemotherapy treatment are known to have worse outcomes than those who receive their treatment as originally scheduled.
“These are the patients, based on our experience, who have the greatest need and will benefit the most from use of a thrombopoietin receptor agonist,” said Dr. Soff.
Oral Therapy Offers a More Convenient Option for Patients
To date, no thrombopoietin receptor agonist has been approved for CIT. But several have shown promise in clinical trials. Dr. Soff also recently led a phase 3 clinical trial of a different thrombopoietin receptor agonist, romiplostim, for patients with gastrointestinal cancers and persistent CIT. Romiplostim also proved very effective to treat CIT, but it needs to be given as an injection.
There is pretty clear evidence that dose reduction or delay has an impact on cancer outcomes, and CIT is a common reason that doses would be delayed or reduced. Our goal here is to avoid compromising the cancer treatment.
Dr. Gerald Soff
As an oral medication, avatrombopag has the advantage that patients wouldn’t need to travel to an infusion center to receive it, Dr. Soff said. For those who have to travel long distances for their chemotherapy cycles, reducing trips to the clinic can be a big bonus.
“You can imagine if someone is dealing with metastatic cancer and they’re not feeling great, and they’re trying to maintain a life, having to go in every single week for a shot is not ideal,” Dr. Soff said. “If there’s a good oral option, that would be very appealing for many people.”
Measuring Success: Platelet Recovery and Treatment Continuity
In the clinical trial of avatrombopag, Dr. Soff and his colleagues were looking for two positive effects of the study drug. Patients needed to recover from low platelet counts within two weeks and that platelet count needed to stay high through the next chemotherapy cycle. Of the 23 patients who received avatrombopag, 65% hit both these metrics, as compared to only 17% of those who received placebo treatment. That’s a very significant difference, Dr. Soff said.
Many of the patients in the trial have continued receiving the drug for the long term. Dr. Soff and his colleagues are now following them to understand whether the medication has a continued, long-term benefit.
They also want to study whether avatrombopag could benefit patients with other types of tumors. There’s no reason to think it wouldn’t, Dr. Soff said. They focused on gastrointestinal cancers to minimize treatment differences among their patients, but patients with many other types of cancers also have to contend with CIT and treatment delays.
“There is pretty clear evidence that dose reduction or delay has an impact on cancer outcomes, and CIT is a common reason that doses would be delayed or reduced,” Dr. Soff said. “Our goal here is to avoid compromising the cancer treatment.”
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