Targeted Drug Maintenance After Stem Cell Transfer Keeps Rare Cancer in Remission

A single-patient case report published in Annals of Hematology describes sustained complete remission in a patient with BRAF V600E-mutant histiocytic sarcoma who received BRAF/MEK inhibitor maintenance therapy after allogeneic stem cell transplantation. Histiocytic sarcoma is a rare and aggressive malignancy with poor outcomes under conventional chemotherapy, and activating MAPK pathway alterations such as BRAF V600E mutations have provided a rationale for targeted treatment.

According to the report, the patient had refractory disease that achieved complete remission following BRAF/MEK inhibition. The patient then underwent allogeneic stem cell transplantation, and maintenance therapy with the BRAF inhibitor dabrafenib combined with the MEK inhibitor trametinib was started early after engraftment. During follow-up exceeding one year, the patient remained in sustained complete remission, with no radiological or molecular evidence of disease.

Molecular monitoring supported the clinical findings. Circulating tumor DNA analysis remained negative for mutations that had previously been detected, suggesting the absence of measurable molecular disease during the maintenance period. The authors report that this integrated strategy, combining targeted therapy, allogeneic transplantation, and post-transplant maintenance, may enable durable disease control in high-risk BRAF-mutant histiocytic sarcoma.

The authors emphasize that the durability of responses to BRAF/MEK inhibition and the role of post-transplant maintenance have remained unclear, and that this case warrants further evaluation. As a case report of a single patient, the findings do not establish efficacy for the approach in broader populations, and the follow-up period, while exceeding one year, cannot demonstrate long-term outcomes. The article is an open-access case report published under a share-first early-access model, citable with a permanent DOI ahead of the final version of record.

The report, authored by Ihab Karim and colleagues, adds to the limited published experience on sequencing targeted therapy with transplantation in histiocytic sarcoma. It suggests a treatment strategy for consideration in high-risk BRAF-mutant cases while leaving its general applicability to be tested in larger studies.

Subject of Research: Post-transplant BRAF/MEK inhibitor maintenance in BRAF V600E-mutant histiocytic sarcoma

Article Title: Post-transplant BRAF/MEK inhibitor maintenance sustains complete remission in BRAF V600E-mutant histiocytic sarcoma

Article References: Karim, I., Arnold, T., Bräuninger, A., Dohse, M., Schell, F., Samra, M. A., Tarawneh, T., Burchert, A., Gattenlöhner, S., & Sohlbach, K. (2026). Post-transplant BRAF/MEK inhibitor maintenance sustains complete remission in BRAF V600E-mutant histiocytic sarcoma. Annals of Hematology. https://doi.org/10.1007/s00277-026-07277-6

Image Credits: AI Generated

DOI: 10.1007/s00277-026-07277-6

Keywords: histiocytic sarcoma, BRAF V600E, dabrafenib, trametinib, allogeneic stem cell transplantation, maintenance therapy, MAPK pathway, circulating tumor DNA, complete remission, case report, Post-transplant, BRAF