Fig. 1

Clinical course and tumor profile of a patient with cancer bearing an amplified HER2 E401G mutation. A Clinical course before and after basket trial with trastuzumab and pertuzumab. Carcinoembryonic antigen (CEA) and cancer antigen 125 (CA125) are tumor markers that reflect the disease status of the patient. Bold arrows indicate the timing of the multi-gene panel tests with FoundationOne CDx® (red arrow) and Gardant360® (blue arrows). CBDCA, carboplatin; GEM, gemcitabine; nab-PTX, nab-paclitaxel; VAF, variant allele fraction. B Results of FoundationOne CDx® test, a multi-gene panel test. Among the detected variants, only those considered pathogenic are shown. Gene amplifications interpreted as equivocal (four copies) are not shown. C Results of computed tomography. The left image is before start of trastuzumab and pertuzumab combination therapy (T + P); the right image is after discontinuation of therapy. Red arrows indicate abdominal lymph node metastases; blue arrows indicate inguinal lymph node metastases. Yellow arrows point to skin edema thought to be associated with skin invasion by cancer. D Pathological findings of cancer tissue (inguinal lymph node biopsy specimen) at the time of diagnosis of cancer. E Pathology findings of skin biopsy specimen when skin invasion of cancer was confirmed, before T + P was discontinued