PMC9378774_01
CT scans of the chest showed that patient 1 had a complete radiological response of mediastinal masses after treatment with pembrolizumab in combination with chemotherapy. (A) Mediastinal masses at diagnosis, lesion has been marked with red arrows. (B) Mediastinal masses before treatment with pembrolizumab combined with chemotherapy. (C) Mediastinal masses are markedly improved after treatment with four cycles of pembrolizumab combined with chemotherapy. (D) Disappearance of mediastinal masses in follow-up.
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PET-CT and CT scans showed an abnormal shadow in the anterior mediastinum, mediastinal lymph node metastasis, and right femoral neck metastasis with pathological fracture of the femur (Figure 1A). A CT-guided percutaneous mediastinal mass biopsy revealed low differentiated squamous cell carcinoma arising from the thymus, with CD117(+), P40(+), CK focally (+), WT1 focally (+), CK7(+), CD5(-), TTF-1(-), NapsinA(-), and SALL4(-) (Supplementary Figure 1A). After two cycles of chemotherapy, tumor size in the anterior mediastinum was reduced (Figure 1B). PD-L1 expression on tumor cells. PD-L1 tumor cell proportion score (TPS) was 85% (clone SP142, Ventana, Supplementary Figure 1B). After four cycles of the combination therapy, her tumor in the mediastinum almost disappeared (Figure 1C). Afterwards, the patient underwent pembrolizumab maintenance treatment of 200 mg every 3 weeks for 1 year and mediastinal tumor masses had disappeared completely (Figure 1D).
X-ray films of the right femur (A) before surgery and (B) after surgery.
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Subsequently, she received proximal femur tumor excision and artificial femoral head replacement in June 2019 (Figure 2). The treatment timeline is shown in Supplementary Figure 2.
PMC9378774_02
Representative images of the CT scan. (A) The pleura and liver lesions at diagnosis, lesion has been marked with red circles. (B) Disappearance of pleura lesions and shrinkage of liver lesions after four cycles of chemotherapy combined with pembrolizumab. (C) Follow-up after radiofrequency ablation.
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However, regular outpatient follow-up CT scan examination in July 2020 found multiple pleural nodules and liver lesions (Figure 3A). After four cycles of the combination therapy, her metastatic pleura nodules disappeared and liver lesions were strikingly reduced with an evaluation of partial response by RECIST version 1.1 (Figure 3B). She continued to have no evidence of disease with excellent performance status and quality of life so far (Figure 3C). The treatment timeline is shown in Supplementary Figure 3.
Representative micrographs. (A) Liver lesion biopsy, squamous cell carcinoma. (B) PD-L1 expression, 5% PD-L1 expression on tumor cells.
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Additionally, ultrasound-guided percutaneous liver lesion biopsy was carried out, showing squamous cell carcinoma arising from the thymus, with CD117(+), P40(+), P63(+), CK(+), CD5 focally (+), CK5/6(+), Hepatocyte(-), and Glypican-3(-) (Figure 4A). Upon immunohistochemical analysis, the tumor demonstrated 5% positivity for PD-L1 expression via clone SP142 antibody [PD-L1 tumor cell proportion score (TPS) = 5%, Figure 4B].