{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,17]],"date-time":"2026-06-17T04:57:43Z","timestamp":1781672263395,"version":"3.54.5"},"reference-count":31,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2026,6,17]],"date-time":"2026-06-17T00:00:00Z","timestamp":1781654400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Oncol."],"abstract":"<jats:p>Ado-trastuzumab emtansine (T-DM1) remains an established adjuvant option for patients with human epidermal growth factor receptor 2 (HER2)-positive early breast cancer and residual invasive disease after neoadjuvant treatment. Severe, persistent thrombocytopenia deviating from the usual cyclic pattern is uncommon and clinically challenging. We report a 50-year-old woman who developed sustained grade 4 thrombocytopenia after three cycles of adjuvant T-DM1, following prior platinum-based chemotherapy and during adjuvant radiotherapy. The thrombocytopenia was refractory to recombinant human thrombopoietin and hetrombopag. Additional evaluations found no evidence of splenomegaly, peripheral platelet destruction, clonal hematologic disease, or a localized radiation effect on the sampled marrow. Sequential marrow evaluations supported megakaryocytic maturation impairment, with initial depletion followed by quantitative recovery but persistently few platelet-producing forms, without dysplasia or fibrosis. Platelet counts repeatedly declined after romiplostim interruption and recovered after reintroduction, allowing long-term stabilization with a threshold-based intermittent regimen. Following multidisciplinary discussion, further anti-HER2 therapy was withheld because of the severely compromised thrombopoietic reserve. As adjuvant antibody-drug conjugate (ADC) strategies continue to evolve, this case suggests that severe non-cyclic thrombocytopenia may occur early during HER2-directed ADC therapy. It supports the value of sequential marrow assessment in selected refractory cases and provides clinical context for individualized romiplostim support in prolonged thrombocytopenia.<\/jats:p>","DOI":"10.3389\/fonc.2026.1859304","type":"journal-article","created":{"date-parts":[[2026,6,17]],"date-time":"2026-06-17T04:50:45Z","timestamp":1781671845000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":0,"title":["Case Report: Persistent severe thrombocytopenia after adjuvant ado-trastuzumab emtansine with sequential bone marrow findings and romiplostim support"],"prefix":"10.3389","volume":"16","author":[{"given":"Dan","family":"Qiao","sequence":"first","affiliation":[{"name":"Department of Medical Oncology, Shaanxi Provincial Cancer Hospital","place":["Xi\u2019an, Shaanxi, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Lei","family":"Nie","sequence":"additional","affiliation":[{"name":"Department of 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