Case report: Disitamab vedotin combined with immunotherapy demonstrated excellent efficacy in scrotal Paget's disease with Her-2 overexpression.

Background: Extramammary Paget's disease (EMPD) is a rare epithelial malignancy, and approximately 30%-40% of EMPD patients overexpress human epidermal growth factor receptor 2 (Her-2). Currently, there are no established standard treatments for advanced EMPD while anti-Her-2 therapy is recommended for Her-2-positive cases. Case presentation: Here, we report a 51-year-old male diagnosed with advanced Her-2-positive EMPD, presenting with numerous lymph node metastases. This patient received disitamab vedotin (an antibody-drug conjugate, targeting Her-2) combined with serplulimab as first-line treatment. After seven cycles of combination therapy, the patient tolerated the treatment well and the lymph node lesions continued to shrink. However, the patient developed immunotherapy-related pneumonia following the eighth treatment. Hormone therapy was administered while all the anti-tumor therapies were halted. After the pneumonia improved, the patient underwent positron emission tomography-computed tomography, revealing a complete response to his tumor. To consolidate the effect, he received another five cycles of disitamab vedotin monotherapy as maintenance therapy, without experiencing any adverse events. To date, the patient has remained in good health without any recurrence 10 months after drug discontinuance. Conclusion: Disitamab vedotin combined with immunotherapy demonstrated a long-term clinical benefit in advanced Her-2-positive EMPD. For rare solid tumors with Her-2 overexpression, disitamab vedotin combined with immunotherapy might offer a viable therapeutic choice.

Establishment of a trastuzumab-resistant extramammary Paget disease model: loss of PTEN as a potential mechanism.

BACKGROUND/OBJECTIVES: Extramammary Paget disease (EMPD) is a rare, cutaneous intraepithelial adenocarcinoma typically treated with wide local excision. Unfortunately, a number of patients with metastases show poor responses to chemotherapy. While some studies have explored trastuzumab's effectiveness against EMPD positive for human epidermal growth factor receptor 2 (HER2), trastuzumab resistance (TR) may emerge after anti-HER2 therapy. METHODS/SUBJECTS: In this study, we established TR EMPD patient-derived xenografts (PDX) that replicated the histological and HER2 expression traits of naive EMPD tumours. RESULTS: Cancer gene analyses revealed a loss of the PTEN gene in TR tumours, which was further confirmed by immunohistochemical staining and immunoblotting to test for protein expression levels. Reduced PTEN levels correlated with increased protein kinase B (Akt) phosphorylation and p27 downregulation, suggesting a potential mechanism for trastuzumab resistance in EMPD cells. In the trastuzumab-sensitive EMPD-PDX mouse model, PTEN inhibitors partially restored trastuzumab-mediated tumour regression. The TR EMPD-PDX responded favourably to targeted therapy (lapatinib, abemaciclib, palbociclib) and chemotherapy (eribulin, docetaxel, trastuzumab deruxtecan). CONCLUSIONS: This study demonstrates an innovative TR EMPD-PDX model and introduces promising antineoplastic effects with various treatments for TR EMPD tumours.

Phase II clinical trial of docetaxel and trastuzumab for HER2-positive advanced extramammary Paget's disease (EMPD-HER2DOC).

BACKGROUND: No consensus has been reached regarding the optimal chemotherapy for metastatic extramammary Paget's disease (EMPD), a rare cutaneous adenocarcinoma, because of the lack of solid evidence from prospective trials. However, the immunohistochemical profile of EMPD reportedly resembles that of breast cancer, particularly in terms of human epidermal growth factor receptor 2 (HER2) expression, suggesting that HER2 is a promising therapeutic target for advanced HER2-positive EMPD. METHODS: In this phase II single-arm trial, 13 Japanese patients received intravenous trastuzumab (loading dose of 8 mg/kg and maintenance dose of 6 mg/kg) and docetaxel (75 mg/m2) every 3 weeks for up to 2 years. The docetaxel dose was reduced or discontinued according to its toxicity. The primary trial endpoints were objective response rate (ORR) after 3 cycles of treatment and safety throughout the study period. RESULTS: All 13 patients completed 3 cycles of combination therapy. The median follow-up was 27.9 months. The ORR was 76.9% (n = 10/13; 90% CI, 50.5-93.4). Frequently observed adverse events were neutropenia (100%), hypoalbuminemia (84.6%), and mucocutaneous infection (84.6%), all of which were well tolerated. CONCLUSION: The combination of docetaxel and trastuzumab demonstrated a favorable clinical effect and acceptable tolerability, which makes it a good treatment option for HER2-positive metastatic EMPD (ClinicalTrials.gov Identifier: UMIN000021311, jRCTs031180073).

Preliminary analysis of the efficacy of Mohs micrographic surgery combined with photodynamic therapy in a case of noninvasive extramammary Paget's disease.

PURPOSE: To evaluate the efficacy of Mohs micrographic surgery (MMS) combined with photodynamic therapy (PDT) in treating non-invasive extramammary Paget's disease (EMPD). MATERIALS AND METHODS: A 77-year-old male patient with non-invasive EMPD was treated with MMS followed by PDT. Preoperative fluorescence localization using 5-aminolevulinic acid (ALA) was performed to determine the surgical scope. MMS was conducted under lumbar anesthesia with intraoperative frozen-section pathology. Postoperative PDT was administered weekly for three sessions. RESULTS: The patient achieved negative surgical margins after two rounds of intraoperative pathology. Postoperative follow-up over two years showed no recurrence, and the patient did not experience significant adverse reactions. CONCLUSION: The combination of MMS and PDT was effective in treating non-invasive EMPD, demonstrating favorable clinical outcomes and no recurrence over the two-year follow-up period.

Treatment of extramammary Paget disease with imiquimod in a real-life setting: a multicentre retrospective analysis in Spain.

BACKGROUND: Topical imiquimod has been shown to be an effective treatment for extramammary Paget disease (EMPD), although available evidence supporting its use is based on case reports and small series of patients. OBJECTIVES: To investigate the therapeutic outcomes and analyse potential clinicopathological factors associated with the imiquimod response in a large cohort of patients with EMPD. METHODS: Retrospective chart review of 125 patients with EMPD treated with imiquimod at 20 Spanish tertiary-care hospitals. RESULTS: During the study period, patients received 134 treatment regimens with imiquimod, with 70 (52.2%) treatments achieving a complete response (CR), 41 (30.6%) a partial response and 23 (17.2%) no response. The cumulative CR rates at 24 and 48 weeks of treatment were 46.3% and 71.8%, respectively, without significant differences between first-time and previously treated EMPD. Larger lesions (≥ 6 cm; P = 0.04) and EMPD affecting > 1 anatomical site (P = 0.002) were significantly associated with a worse treatment response. However, the CR rate did not differ significantly by the number of treatment applications (≤ 4 vs. > 4 times per week; P = 0.112). Among patients who achieved CR, 30 of 69 (43%) treatments resulted in local recurrences during a mean follow-up period of 36 months, with an estimated 3- and 5-year recurrence-free survival of 55.7% and 36.4%, respectively. CONCLUSIONS: Imiquimod appears as an effective therapeutic alternative for both first-line and previously treated EMPD lesions. However, a less favourable therapeutic response could be expected in larger lesions and those affecting > 1 anatomical site. Based on our results, a three to four times weekly regimen of imiquimod with a treatment duration of at least 6 months could be considered an appropriate therapeutic strategy for patients with EMPD.

NECTIN4-targeted antibody-drug conjugate is a potential therapeutic option for extramammary Paget disease.

Extramammary Paget disease (EMPD) is a rare skin cancer mainly found in areas rich in apocrine sweat glands. Since the effective treatments for advanced and/or metastasized EMPD are limited, there is an urgent need to develop novel therapeutic approaches. Nectin cell adhesion molecule 4 (NECTIN4) is highly expressed in cancers and considered to be a promising therapeutic target. NECTIN4 is also expressed in EMPD, but its role and the efficacy of NECTIN4-targeted therapy in EMPD remain unclear. This study investigated the potential of NECTIN4 as a novel therapeutic target for EMPD. NECTIN4 expression was immunohistochemically analysed in EMPD patients' primary (118 samples) and metastatic (21 samples) lesions. Using an EMPD cell line, KS-EMPD-1, the effects of NECTIN4 inhibition on cell proliferation and migration were investigated. NECTIN4 was expressed in primary and metastatic EMPD lesions, and the H-score of NECTIN4 staining was significantly higher in metastatic lesions than in primary ones. Knockdown of NECTIN4 significantly inhibited cell proliferation and affected cell migration. The cytotoxic effects of NECTIN4-targeted antibody-drug conjugate (ADC) were further evaluated, revealing a significant decrease in EMPD cell viability. In conclusion, NECTIN4 is a potential therapeutic target and NECTIN4-targeted ADC is promising as a therapeutic option for EMPD.

Recent treatment and prognosis in 643 patients with extramammary Paget's disease.

Information about extramammary Paget's (EMPD) treatment is limited because of the rarity of the disease. The prognosis differs between in situ EMPD and invasive EMPD; therefore, therapy should be planned according to the disease stage. We collected data on 643 EMPD cases treated between 2015 and 2019 in Japan and assessed recent trends in EMPD treatment and prognosis based on the EMPD-oriented TNM staging. Among the 643 patients, 317 had stage 0 (49.3%), 185 had stage I (28.8%), 51 had stage II (7.9%), 18 had stage IIIA (2.8%), 48 had stage IIIB (7.5%) and 24 had stage IV (3.7%) disease. Each stage showed a distinct survival curve, with the exception of stages II and IIIA. Curative surgery was most common in patients with stage 0-III disease. Chemotherapy was the first-line therapy, mainly in patients with stage IIIB and IV disease, most commonly with docetaxel (DTX), followed by DTX + tegafur gimeracil oteracil potassium (TS-1) and TS-1. Patients with local disease exhibited a 4.4% recurrence rate. Univariate analysis revealed no prognostic differences according to age, sex or primary tumour site. SLNB was not related to disease-specific survival. In multivariate analysis, female sex significantly predicted local relapse in stage 0-I (HR 3.09; 95% CI, 1.13-8.43), and initial treatment with curative surgery was significantly protective in terms of disease-specific survival in stage II-IIIA (HR, 0.17; 95% CI, 0.04-0.71) and stage IIIB-IV (HR 0.16; 95% CI, 0.05-0.51). Further clinical studies are needed to improve the prognosis of patients with stage II-IV EMPD.

Eribulin for patients with metastatic extramammary Paget disease: Study protocol for a single-arm phase II trial.

Extramammary Paget disease (EMPD) is a rare cutaneous malignancy that predominantly affects the anogenital areas of the elderly. Although the efficacy of docetaxel and other cytotoxic agents for advanced EMPD has been reported in small retrospective case studies, no treatment has been proven effective in prospective clinical trials. We established the world's first in vivo EMPD experimental model (a patient-derived xenograft model). In our treatment experiment, xenograft tumours showed a remarkable response to eribulin. This study evaluates the efficacy of eribulin for patients with advanced EMPD. In October 2022, we started a single-arm phase II trial to evaluate the efficacy of eribulin as a treatment for adult patients with unresectable EMPD with measurable lesions. Enrolment in this clinical trial is open to patients with any prior treatment for EMPD. The primary endpoint is overall response rate; the secondary endpoints include disease control rate, overall survival, progression-free survival and adverse events. The study protocol was approved by the Ethics Committee of Hokkaido University and the other collaborating institutions. If the primary endpoint is met, it is our hope that eribulin will be regarded as a standard medication for patients with advanced EMPD.

Case report: Hematoporphyrin injection (HpD) photodynamic therapy for the treatment of groin extramammary Paget's disease in an elderly male patient.

Hematoporphyrin Derivative-Photodynamic Therapy (HpD-PDT) is a modality for cancer treatment, particularly suitable for challenging sites or elderly patients who can benefit from its minimally invasive and selective nature. We report a case of groin extramammary Paget's disease (EMPD) in a male patient with a lesion located in the right mons pubis. The patient was deemed unsuitable for surgical treatment due to his advanced age, underlying health conditions, extensive rash area, and the specific location of the groin lesion. He opted for hematoporphyrin photodynamic therapy instead of traditional wide local excision. The tumors were successfully treated, with no recurrence observed during the follow-up period. We suggest that hematoporphyrin photodynamic therapy may be an effective alternative to conventional surgery for the treatment of extramammary Paget's disease.

Role of androgen signaling in androgen receptor-positive extramammary Paget's disease: Establishment of organoids and their biological analysis as a novel therapeutic target.

BACKGROUND: Extramammary Paget's disease (EMPD) is a rare intraepithelial adenocarcinoma that mainly affects the anogenital and axillary regions. Although its etiology has not been fully elucidated, there is evidence that androgen receptors (AR) are expressed in most cases of EMPD. However, the role of androgen signaling in the pathogenesis of EMPD remains unclear. OBJECTIVE: To evaluate the role of androgen signaling in tumor growth of AR-positive EMPD. METHODS: Patient-derived organoids were established and cultured from two AR-positive EMPD patients: one man and one woman. Cultured organoids were treated with androgen agonists and/or antagonists, then subjected to analysis of changes in organoid proliferation, as well as changes in androgen signaling pathway-specific genes. RESULTS: Organoid cultures were established from each EMPD sample. These organoids were immunohistologically and genetically identical to the original tumor. For each organoid sample, viable cell number increased in response to androgen exposure. The mRNA level of Fkbp5, a known AR target gene, increased in a concentration-dependent manner in organoids exposed to the synthetic androgen R1881. Conversely, the AR inhibitor darolutamide suppressed the viable cell number in a concentration-dependent manner. The mRNA expression levels of MKI67 and Fkbp5 were also suppressed by darolutamide. CONCLUSION: Our results indicate that androgen signaling is a key pathway involved in the growth of AR-positive EMPD. Therefore, androgen signaling inhibition may be a novel treatment option for EMPD patients who require systemic therapy.

KS-EMPD-1: a novel cell line of primary extramammary Paget's disease.

Extramammary Paget's disease (EMPD) is a rare skin cancer that mainly occurs in apocrine sweat gland-rich areas in elderly people. The prognosis of metastatic EMPD is unfavorable because of the lack of fully effective systemic therapies. However, the difficulty in establishing a model of EMPD has hampered basic research for exploring its pathogenesis and optimal treatments. Here, we established for the first time an EMPD cell line (named KS-EMPD-1) from a primary tumor on the left inguinal region of an 86-year-old Japanese male. The cells were successfully maintained for more than 1 year, with a doubling time of 31.2 ± 0.471 h. KS-EMPD-1 exhibited constant growth, spheroid formation, and invasiveness, and was confirmed to be identical to the original tumor by short tandem repeat analyses, whole exome sequencing, and immunohistochemistry (CK7+CK20-GCDFP15+). Western blotting of the cells revealed the protein expression of HER2, NECTIN4, and TROP2, which have recently attracted attention as potential therapeutic targets for EMPD. KS-EMPD-1 was highly sensitive to docetaxel and paclitaxel on chemosensitivity test. The KS-EMPD-1 cell line is a promising resource for basic and preclinical research on EMPD to better define the tumor characteristics and treatment strategy of this rare cancer.

Treatment outcomes of advanced/metastatic extramammary Paget's disease in Korean patients: KCSG-RC20-06.

BACKGROUND: Extramammary Paget's disease (EMPD) is rare. There are no standard treatments due to its rarity and few clinical trials. METHODS: The objective of this multicenter study was to investigate treatment outcomes of Korean patients with advanced/metastatic EMPD. Data were collected retrospectively from 14 institutions participating in Korean Cancer Study Group (KCSG) Rare Cancer Committee. RESULTS: A total of 37 patients were identified. Of these 37 patients, 6 received locoregional therapy as a first-line treatment. In 31 patients who received systemic chemotherapy as a first-line treatment, platinum-based chemotherapy (n = 22) achieved an objective response rate (ORR) of 45.5% and a median progression-free survival (PFS) of 7.89 months. Taxane-based chemotherapy (n = 8) achieved an objective response rate of 62.5% and median PFS of 9.73 months. In second-line chemotherapy, platinum-based chemotherapy (n = 4) had a disease control rate (DCR) of 75.0% and median PFS of 3.45 months. Taxane-based chemotherapy (n = 8) had a DCR of 75.0% and a median PFS of 8.67 months. Six patients received anti-human epidermal growth factor receptor 2 (HER2) antibody during first- and second-line chemotherapy. Overall, systemic chemotherapy combined with anti-HER2 antibody had an ORR of 100% and a median PFS of 13.31 months. The ORR and PFS with systemic chemotherapy combined with trastuzumab was better than platinum- and taxane-based chemotherapy only. CONCLUSIONS: Due to its rarity, advanced or metastatic EMPD still has no established standard treatment. Results of our study indicate that the combination of trastuzumab with taxane has longer survival than trastuzumab monotherapy or conventional platinum- or taxane-based chemotherapy.

Efficacy of chemotherapies for unresectable extramammary Paget disease: a single-centre retrospective study.

BACKGROUND: Extramammary Paget disease (EMPD) is a cutaneous neoplasm that can metastasize to the lymph nodes and distant organs, resulting in a poor prognosis. For unresectable distant metastases of EMPD, no consensus has been reached regarding optimal chemotherapy owing to a lack of data. OBJECTIVES: To evaluate the efficacy of three regimens: docetaxel (DTX) monotherapy; combination therapy with 5-fluorouracil, epirubicin, carboplatin, vincristine and mitomycin C (FECOM); and tegafur (S-1) monotherapy. METHODS: This single-centre retrospective study included 32 patients diagnosed with unresectable EMPD and treated with chemotherapy between 2002 and 2022 at the National Cancer Center Hospital in Japan. Patient characteristics, responses to treatment and survival data were evaluated for each of the first-line therapies. RESULTS: Among the 17 patients who received DTX monotherapy, the response rate (RR) and disease control rate (DCR) were 47% and 77%, respectively. The median progression-free survival (PFS) and overall survival (OS) were 12.3 months [95% confidence interval (CI) 6.1-26.6] and 19.2 months (95% CI 8.5-not reached), respectively. Among the 11 patients who received combination FECOM chemotherapy, the RR and DCR were 55% and 64%, respectively. The median PFS and OS were 6.8 months (95% CI 3.5-not reached) and 13.4 months (95% CI 8.6-21.3), respectively. Among the four patients who received S-1 monotherapy, the RR and DCR were 0% and 25%, respectively. The median PFS and OS were 5.4 months (95% CI 2.3-not reached) and 12.5 (95% CI 2.3-not reached) months, respectively. CONCLUSIONS: Further investigations with prospective analysis are required to confirm these findings.

Photodynamic therapy in a patient with perianal extramammary Paget's disease.

Extramammary Paget's disease is a rare neoplasm of apocrine gland-bearing areas of the skin. One of the most common localizations of such a tumor is the perianal area. Surgery is the most frequently reported therapy. However, it is an invasive procedure and complicated by a high recurrence rate. An alternative to surgical treatment may be non-invasive photodynamic therapy. We describe in this article the case of a 69-year-old patient with extramammary Paget's disease (a large tumor in the perianal area 22 × 18 cm) successfully treated with chlorin e6 photodynamic therapy.

Overexpression of heat shock protein 90 through the downregulation of miR-9-5p in extramammary Paget's disease.

Heat shock protein 90 (HSP90) facilitates diverse cellular processes by interacting process with more than 200 client proteins. Overexpression of HSP90 contributes to the pathogenesis of various malignant tumors, and HSP90 inhibitors attenuate the progression of malignant tumors in vitro/vivo. Numerous clinical trials have used HSP90 inhibitors to treat several cancers, and pimitespib (an HSP90 inhibitor) is covered by insurance for advanced gastrointestinal stromal tumor in Japan. In this study, we investigated the expression pattern of HSP90 and analyzed its clinical significance in extramammary Paget's disease (EMPD). All 77 EMPD tissues investigated were positive for HSP90 expression. The immunoreactivity of HSP90 in fetal cases due to EMPD tended to be highly stained. Although there was no significant difference in HSP90 mRNA levels between 24 paired lesional and nonlesional tissues, microRNA-inhibiting HSP90 levels in tumor tissues were significantly decreased compared with those in normal tissues. Thus, HSP90 may play an important role in the pathogenesis of EMPD and may be a novel therapeutic target for EMPD.