Healthcare professional holding a tray of blood samples at ISTH 2026 conference on cancer-associated thrombosis.
Articles / Hematology 07/30/2026

ISTH 2026: Key Takeaways in Cancer-Associated Thrombosis and Thrombocytopenia 

Medical professional in white lab coat smiling, representing healthcare and oncology expertise. William Archibald, MD Young male oncologist in white lab coat smiling, standing in a bright medical office, representing cancer research and treatment expertise. Kevin Zablonski, MD

Key Points

  • Immune checkpoint inhibitor–associated immune thrombocytopenia occurs in approximately 1 in 400 patients, and many can be safely rechallenged without recurrence.
  • The role of thrombopoietin receptor agonists in chemotherapy-induced thrombocytopenia remains debated, with emerging data suggesting potential benefit in maintaining chemotherapy dose intensity despite limited survival evidence.
  • Use of the YEARS algorithm in patients with cancer may safely reduce reliance on CT pulmonary angiography while maintaining diagnostic accuracy for pulmonary embolism.

The 2026 International Society on Thrombosis and Haemostasis (ISTH) Congress held in Paris, France, was well attended, with more than 6000 attendees and among the highest abstract submission totals in the past 5 years. 

For practicing oncologists, the work of the Scientific and Standardization Subcommittee “Cancer-Associated Thrombosis & Hemostasis” (CATH-SSC) provides the latest guidelines to support the care of patients with cancer. This year’s CATH-SSC presentation highlighted two key topics: Immune checkpoint inhibitor–associated immune thrombocytopenia (ICI-ITP) and chemotherapy-induced thrombocytopenia (CIT). Other recent data shared during the presentation explained important implications for improving patient care. 

Rechallenge After ICI-Associated ITP

The first part of the presentation highlighted the retrospective, multicenter analysis by Rebecca K. Leaf, MD, of Mass General Brigham Cancer Institute, et al. published earlier this year in the journal Blood. This study showed a striking consistency across centers, demonstrating that approximately 1 in 400 patients treated with ICIs develop ITP. Among patients who were rechallenged with ICIs after developing ITP, approximately 70% did not experience a recurrent episode. These findings suggest that selected patients with ICI-associated ITP can often be safely rechallenged, allowing them to continue potentially life-prolonging ICIs and improving outcomes.1

Thrombopoietin Receptor Agonists in CIT: Ongoing Debate on Clinical Utility

Second, the presentation addressed the common problem of CIT. Historically, guidance, including that from the CATH-SSC, have not endorsed the use of thrombopoietin (TPO) receptor agonists for patients with CIT. The CATH-SSC meeting featured a spirited debate between Hanny Al-Samkari, MD, of Mass General Brigham Cancer Institute, lead author of the recently published trial, Romiplostim versus Placebo for Chemotherapy-Induced Thrombocytopenia, in the New England Journal of Medicine.2 

Dr. Al-Samkari argued in favor of TPO agonists to maintain chemotherapy dose intensity and treatment schedules, with the goal of improving patient outcomes. Although the trial did not show statistically significant overall survival (OS) benefit, Dr. Al-Samkari debated that available evidence consistently shows more favorable survival curves among patients who are able to maintain chemotherapy dose intensity and frequency with TPO agonists. He repeatedly asked the audience, “What curve do you want your patients to be on?” 

Opposing Dr. Al-Samkari was Cihan Ay, MD, of the Medical University of Vienna, who pointed out that current ISTH guidelines do not recommend the use of TPO agonists for CIT. He argued that Dr. Al-Samkari’s recent trial is not sufficiently compelling to justify changing clinical practice, particularly given the lack of OS and progression-free survival benefit to proceed with making this a routine part of cancer care.3 

Overall, our takeaway was that use of TPO agonists may benefit our patients with CIT, and we would favor their use when contraindications, such as significant liver disease or a history of thrombosis, are not present. 

Risk Stratification for PE in Cancer: Role of the YEARS Algorithm

In the outpatient setting, an open question has been whether clinical risk stratification can safely reduce the use of CT pulmonary angiography (CTPA) for patients with cancer and suspected pulmonary embolism. Current guidelines recommend proceeding directly to CTPA in patients with cancer. However, a recent randomized trial evaluating the YEARS algorithm in patients with active cancer demonstrated non-inferiority while reducing the use of CTPA by 22% when using the YEARS algorithm compared to proceeding directly to CT angiography.4

We look forward to seeing how these advances in science and clinical guidelines continue to evolve and shape the care of our patients with cancer at ISTH 2027 in the beautiful city of Vancouver from June 26-30. 

References

  1. Leaf RK, Mones JV, Shenoy T, et al. Immune thrombocytopenia in patients treated with immune checkpoint inhibitors. Blood. 2026;147(12): 1351–1364. doi:10.1182/blood.2025031449
  2. Al-Samkari H, Muñoz C, Geredeli C, et al. Romiplostim versus placebo for chemotherapy-induced thrombocytopenia. N Engl J Med. 2026;394:1061-1073. doi:10.1056/NEJMoa2511882
  3. Soff G, Leader A, Al-Samkari H, et al. Management of chemotherapy-induced thrombocytopenia: guidance from the ISTH Subcommittee on Hemostasis and Malignancy. J Thromb Haemost. 2024; 22(1):53-60. doi:10.1016/j.jtha.2023.09.031
  4. Akerboom B, Martens E SL, Stals A AM, et al. YEARS algorithm for diagnosis of suspected pulmonary embolism in patients with cancer: A randomized clinical trial. JAMA. Published online July 12, 2026. doi:10.1001/jama.2026.10676