case_images: PMC11439626_01
case_images: Course of the disease with treatment history and images. Red arrows show the location of tumor lesions.
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case_images: PMC11439626_01_fonc-14-1367140-g001.jpg
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case_images: Pathology in combination with abdominal and pelvic magnetic resonance imaging (MRI) examination confirmed that the tumor was an endometrial clear cell carcinoma (Type II EC) with a size of 1.5x0.9x0.3 cm3 ( Figure 1 ;  Supplementary Table 1 ). Histopathological examination was performed and the IHC exhibited estrogen receptor (ER)-, progesterone receptor (PR)-, MSH2 (+), MSH6 (+), MLH1 (+), PMS2 (+), HER2 (2+), and Ki-67 proliferation marker (Ki-67) (30-40%) ( Supplementary Figure 1 ). In September 2022, abdominopelvic MRI revealed the presence of abdominal and peritoneal metastases ( Figure 1 ). ADCs have been reported to be effective in HER2-low expression cancers, the patient was recommended the cross-indication anti-HER2 ADC, RC48 (initially at a dosage of 60 mg, followed by 120 mg every two weeks). After 3 cycles of treatment, the computed tomography (CT) scan showed significantly reduced in the pelvic metastatic lesion by 65% ( Figure 1 ). After 10 cycles of treatment, CT examination unveiled the vanishing of multiple metastatic lesions ( Figure 1 ), while the CA-125 level returned to its normal range ( Supplementary Figure 4 ). In June 2023, positron emission tomography-CT examination revealed a sustained stability without any signs of progression ( Figure 1 ).