When chemotherapy saves your life but threatens to stop working because your blood can't clot properly, you face an agonizing choice. For gastrointestinal cancer patients experiencing chemotherapy-induced thrombocytopenia—dangerously low platelet counts that develop mid-treatment—that choice has just become far less grim. A Phase II clinical trial led by researchers at Sylvester Comprehensive Cancer Center and Mass General Hospital has shown that avatrombopag, an oral medication already approved for liver disease patients, could transform how clinicians manage this common and serious side effect.
The stakes are deceptively simple but profound. Platelets are blood cells essential for clotting; without enough of them, patients face life-threatening bleeding from minor injuries. When chemotherapy tanks these numbers, oncologists often must delay or reduce the next dose of treatment—a decision with measurable consequences. Patients who receive delayed or reduced chemotherapy have significantly worse outcomes than those who proceed on schedule. For people fighting metastatic cancer, these gaps in treatment can mean the difference between remission and progression.
Dr. Gerald A. Soff, chief of classical hematology at Sylvester, launched the trial with an ambitious goal: enroll 40 gastrointestinal cancer patients with persistent chemotherapy-induced thrombocytopenia. The results proved so striking that the team stopped early at their interim analysis of just 23 patients. Among those who received avatrombopag, 65 percent met both critical treatment targets: recovering platelet counts within two weeks and maintaining them through the next chemotherapy cycle. By contrast, only 17 percent of placebo recipients achieved both goals. "That's a very significant difference," Soff said.
What makes this finding especially promising is the drug's form: a pill, not an injection. Thrombopoietin receptor agonists—a class of medications designed to boost platelet production—have shown promise before, but existing options require infusions or regular injections at specialized clinics. Avatrombopag, already FDA-approved for thrombocytopenia in liver disease patients, eliminates that burden. For someone juggling metastatic cancer, fatigue, and the logistics of traveling for chemotherapy cycles, the convenience cannot be overstated. "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," Soff said. "If there's a good oral option, that would be very appealing to many people."
The trial enrolled only patients with persistent chemotherapy-induced thrombocytopenia—those whose platelet counts wouldn't naturally recover between cycles, unlike the majority of chemotherapy patients who bounce back without intervention. Many trial participants have continued the drug long-term, and Soff's team is now tracking whether avatrombopag maintains its benefit over time. They're also exploring whether the medication could help patients with other tumor types, not just gastrointestinal cancers.
The results were presented at the 2026 American Society of Clinical Oncology annual meeting. While no thrombopoietin receptor agonist has yet been approved specifically for chemotherapy-induced thrombocytopenia, avatrombopag's oral delivery and proven efficacy position it as a strong candidate. For patients caught between the demands of ongoing treatment and the fragility of dangerously low platelets, this development offers something precious: a simpler path forward.