YO27 - Drastic response to cetuximab in metastatic eccrine porocarcinoma with EGFR amplification

Case summary

Eccrine porocarcinoma (EPC) is a rare skin cancer of the intraepidermal ductal portion of

the sweat gland, accounting for 0.005 - 0.01% of all malignant epithelial tumors. Owing to

the rarity, treatment of metastatic EPC is not standardized. Herein, we present a case of

drastic response to cetuximab and 5-FU/LV of a metastatic EPC with EGFR amplification.

A 70-year-old woman was referred to us for the treatment of EPC. She had been

undergone to excision of a skin lesion in her left breast and axillary lymph nodes before

reference to our hospital. However, 6 months later, a computed tomography (CT) scan

revealed lung metastases and a liver metastasis. Immuno-histological staining of the

primary lesion showed the following: Ki-67 95%, EMA(+), CK5/6(+), p40(+), p63(+), AR(+),

MUC1(+), ER(±), PgR(-), HER2(2+), HER2-FISH(-), GCDFP15(-), GATA3(±), PAX5(-),

S100(-). As an initial chemotherapy, carboplatin and docetaxel were administered every 3

weeks. After 5 cycles, CT scan showed disease progression in lung metastases and

appearance of hepatic lymph nodes metastases.

We performed a comprehensive genomic profiling (CGP) by FoundationOne ®CDx and

identified EGFR amplification (copy number 53). The result of genomic profiling is shown in

Table 1. Based on this result, cetuximab (400 mg/m 2 once, then 250 mg/m 2 per week) in

association with 5-FU/LV (200 mg/m 2 leucovorin, 400 mg/m 2 bolus fluorouracil, and 2400

mg/m 2 infusional fluorouracil per 2 weeks) were administered. All lesions were shrunk

drastically and kept under control without progression for more than a year. Grade 3

hypomagnesemia was observed but manageable.

Given the few cases and the absence of clinical trials in rare cancers, it is important to

collect clinical experiences on rare cancers, especially the cases with the efficacy by the

treatment based on CGP. Our experience suggests a potential role of EGFR inhibition in

advanced EPC, which can help physicians treat this rare and aggressive skin cancer.

Table 1. Comprehensive genomic profiling by FoundationOne ®CDx

Clinical trial identification

Editorial acknowledgement