No abstract

Advanced cutaneous squamous cell carcinoma (cSCC) is treated with chemotherapy and/or radiotherapy, but these typically fail to achieve satisfactory clinical outcomes. There have been no preclinical studies to evaluate the effectiveness of eribulin against cSCC. Here, we examine the effects of eribulin using cSCC cell lines and a novel cSCC patient-derived xenograft (PDX) model. In the cSCC cell lines (A431 and DJM-1 cells), eribulin was found to inhibit tumor cell proliferation in vitro as assessed by cell ATP levels. DNA content analysis by fluorescence-activated cell sorting (FACS) showed that eribulin induced G2/M cell cycle arrest and apoptosis. In xenograft models of cSCC cell lines, the administration of eribulin suppressed tumor growth in vivo. We also developed a cSCC patient-derived xenograft (PDX) which reproduces the histological and genetic characteristics of a primary tumor. Pathogenic mutations in TP53 and ARID2 were detected in the patient’s metastatic tumor and in the PDX tumor. The cSCC-PDX responded well to the administration of eribulin and cisplatin. In conclusion, the present study shows the promising antineoplastic effects of eribulin in cSCC. Also, we established a novel cSCC-PDX model that preserves the patient’s tumor. This PDX could assist researchers who are exploring innovative therapies for cSCC.

Extramammary Paget’s disease (EMPD) is an adenocarcinoma that develops mainly in the genital region of older adults. The prognosis for advanced EMPD is almost always poor; thus, novel therapeutic strategies need to be developed. HER2-targeted antibody–drug conjugates (ADCs) such as trastuzumab emtansine and trastuzumab deruxtecan have proven effective against HER2-positive breast cancers; however, no studies have addressed HER2-targeted ADCs as treatments for EMPD. We examine the efficacy of ADCs against an EMPD patient-derived xenograft (PDX) model harboring pathogenic ERBB2 mutations and investigate the expression levels of HER2 using EMPD clinical samples. Trastuzumab emtansine or trastuzumab deruxtecan was administered intravenously to tumor-bearing NOD/Scid mice. Treatment with trastuzumab emtansine or trastuzumab deruxtecan was found to significantly regress EMPD-PDX tumors in only seven days, with no recurrence observed for 10 weeks. EMPD tumors extracted 48 h after drug administration revealed the TUNEL-positive ratio to be significantly higher for the HER2-targeted ADC-treated tumors than for the control tumors. EMPD patients’ clinical samples revealed a significant correlation between HER2 positivity and invasion, suggesting that HER2 status is associated with tumor progression. Our results suggest that HER2-targeted ADCs could be novel and promising treatment options for patients with EMPD, especially in ERBB2-mutant or ERBB2-overexpressed cases.

Adjuvant nivolumab therapy has been reported to improve the survival of melanoma patients. Acral lentiginous melanoma (ALM) has been reported to be less likely to respond to immune checkpoint inhibitors (ICIs) than other subtypes. However, the efficacy of adjuvant nivolumab therapy for ALM patients remains uncertain due to the low number of cases. In this single-center retrospective case series, we analyzed the clinical data of patients with resected stage III/IV ALM who were referred to our department between April 1, 2004 and March 31, 2022. The analyzed clinical data included age, sex, TNM stage, treatments, adverse events and disease-free survival (DFS). Enrolled patients were divided into a nivolumab group and a non-ICI group according to the adjuvant therapy they received. In total, 27 patients were included. The nivolumab and non-ICI groups had 5 and 22 patients,