A Case of Granulocyte Colony-Stimulating Factor-Producing Lung Adenocarcinoma with KRAS G12V Mutation Responding to Pembrolizumab.

Authors

Katsunori Arai, Hirokazu Tokuyasu, Shuichi Matsuoka, Hiromitsu Sakai, Chika Esumi, Akira Yamasaki

Published in

Internal medicine (Tokyo, Japan). Jul 11, 2026. Epub Jul 11, 2026.

Abstract

We report a rare case of granulocyte colony-stimulating factor (G-CSF)-producing lung adenocarcinoma with a high PD-L1 expression and a KRAS G12V mutation that responded to pembrolizumab. A 72-year-old man presented with leukocytosis, elevated serum G-CSF levels, a diffuse bone marrow fluorodeoxyglucose uptake, and a rapidly progressive lung mass. A biopsy revealed TTF-1 positive adenocarcinoma with a PD-L1 tumor proportion score of 100 % and a KRAS G12V mutation. Pembrolizumab induced marked tumor regression and normalization of the G-CSF levels. However, immune-related pneumonitis resulted in treatment discontinuation. Pembrolizumab may be effective in selected patients with G-CSF-producing lung cancer despite its typically aggressive clinical behavior.

PMID:
42438032
Bibliographic data and abstract were imported from PubMed on 13 Jul 2026.

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