Summary of the 1st ISID-APAC × KSID MCC Interest Group Meeting

Summary of 1st ISID-APAC × KSID MCC Interest Group Meeting

April 9, 2026

Amore Pacific Headquarters, Seoul, Korea

In-person and via Zoom

The inaugural 1ˢᵗ ISID-APAC × KSID MCC Interest Group Meeting established a vital foundation for pan-Asia-Pacific collaboration. The next meeting is planned for October 2027 in Taiwan.

Meeting notes:

Rima Kulikauskas, BS

Director of Specimen Repository, MC3 Institute, University of Washington, US

“How can the MC3 Institute Support the APAC MCC Community?”

• • Launched in January 2025, the MC3 Institute hosts >130 members from 45+ institutions worldwide, with access to a 2,000+ patient repository (>60,000 specimens, 200+ data fields) and five ongoing multi-site studies.
  • The weekly MCC Tumor Board reviews 200+ cases annually via Zoom; the Institute is exploring flexible scheduling to accommodate APAC time zones.
  • Membership is completely free. All APAC clinicians and researchers are warmly invited to join at mc3institute.org or email [email protected] (scan QR code at right).

Trang Chu, PhD (Research group: Peter Goon, PhD FRCP)

Research fellow, Yong Loo Lin School of Medicine, National University of Singapore

“Merkel Cell Carcinoma in Singapore: Current Landscape & Epidemiology”

• • A population-based study (1997–2023) identified 39 MCC cases; crude rate 0.039/100,000 person-years (Age Standardized Rate 0.035). Incidence has risen since 2018 (+0.97%/year), mirroring global trends. Unlike Western populations, limb sites predominated—possibly reflecting cultural sun-avoidance behaviors. Median age was 82 years; 5-year survival was only 30%, with significant unmet needs including absence of MCPyV/ctDNA testing and limited access to several treatment options in Singapore.

Shih-Sung Chuang, MD

Professor, Department of Pathology, Chi-Mei Medical Center, Taiwan

“MCC in Taiwan: Diagnostic Challenges and Epidemiology”

• • A 38-case multi-center review spanning 1994–2022 highlighted two key diagnostic pitfalls: confusion with malignant lymphoma and inadequate sampling in combined MCC-SCC tumors. A distinctive regional feature is arsenic-related MCC, accounting for 13% of cases and linked to historical groundwater contamination; all arsenic-associated cases were MCPyV-negative, as were the combined MCC-SCC tumors, which also carried shorter disease-free survival. Overall MCPyV positivity across all cases was 45%. The Taiwan Cancer Registry recorded a steady age-adjusted incidence of 0.039 per 100,000 from 1997–2022.

Wen Xu, MBBS, FRACP

Associate Professor, The University of Queensland, Princess Alexandra Hospital; Chair, Australasian Merkel Cell Carcinoma Interest Group (AMIGOS)

“MCC Epidemiology and Outcomes in Queensland; AMIGOS and Ongoing Trials”

• • Queensland has one of the world’s highest MCC rates (2.3/100,000 in 2021). Among 1,060 patients (2012–2021), 80% were virus-negative with high TMB, contrasting sharply with Asian cohorts. Recurrence occurred in 46% within 5 years—predominantly within the first 2 years—and only age, stage, and comorbidity independently predicted mortality.
  • The Australasian Merkel Cell Carcinoma Interest Group (AMIGOs), established in 2017 and now numbering 119 members, is led by Dr. Xu and open to international membership. The group has completed or is actively running several trials, including the I-MAT adjuvant immunotherapy trial (results expected at ASCO 2026) and the GOTHAM theranostics study.

Motoki Nakamura, MD, PhD

Associate Professor, Department of Geriatric and Environmental Dermatology, Nagoya City University Graduate School of Medical Sciences

“MCC in Japan & Spatial Omics Analysis in MCC, Focusing on Tertiary Lymphoid Structures”

• • Japanese MCC incidence is 0.2/100,000 (70–80% MCPyV-positive); the first Japanese MCC guidelines were published February 2025.
  • In Dr. Nakamura’s research, tertiary lymphoid structures (TLS) were found in ~2/3 of 71 samples and were a significant prognostic marker specifically in MCPyV-negative cases. Phenocycler spatial proteomics revealed a critical mechanistic difference: in immunotherapy responders, CD8+ T cells densely infiltrate B-cell clusters and reach follicular dendritic cells; in non-responders, T cells remain peripheral to B-cell clusters

Chonghyun Won, MD, PhD

Professor, Department of Dermatology, Asan Medical Center, Seoul, Korea

“MCC in Korea: Interactive Case Discussion”

• • Through interactive case presentations, Dr. Won illustrated Korea’s evolving MCC landscape. A 62-case clinicopathological study (1997–2022) documented high CK20 (96.6%) and synaptophysin (94.4%) positivity and an 80.6% five-year overall survival. Historically, female predominance was observed, likely reflecting longer life expectancy in women that majority of MCC occurs; however, this is now shifting toward male predominance as the broader population ages into the higher-risk age group. Sentinel lymph node biopsy and post-surgical adjuvant radiotherapy significantly improved both progression-free and overall survival, establishing their role in standard Korean MCC management.

Claire Park · Tomoko Akaike, MD · Paul Nghiem, MD, PhD

University of Washington / Fred Hutch Cancer Center, Seattle, WA, USA

“APAC-Relevant Advances in MCC Care: Multidisciplinary Tumor Board and ctDNA Monitoring”

• • The UW MCC Multidisciplinary Tumor Board (hybrid Zoom, shown right) discussed 229 cases over 13 months from 6 countries and 29 US states, with modified clinical management in 63% of cases. International case submissions are accepted at [email protected].
  • The MCC recurrence risk calculator (https://merkelcell.org/prognosis/recur/) estimates individualized recurrence risk based on stage, immune status, and treatment, supporting personalized surveillance planning for clinicians worldwide.
  • ctDNA (Signatera) detects MCC recurrence with 94–95% sensitivity and 86–90% specificity and is now in the 2025 NCCN guidelines. Positive ctDNA typically precedes clinical recurrence by months; a clinical trial is planned for ctDNA+/scan− patients to test preemptive immunotherapy.

Alex Ngo, MBA, MPA

Senior Regional Director, APAC, Natera, Inc.

“How to Order ctDNA Testing in Your Country: Logistics Overview”

• • Signatera (tumor-informed, 16-mutation ctDNA assay, >100 peer-reviewed publications) is available across most APAC countries; Taiwan access is pending regulatory approval. Specimen requirements: 10–20 unstained FFPE slides (>20% tumor) and one 6 mL EDTA tube for germline baseline; monitoring uses Streck cfDNA tubes (avoid butterfly needles).
  • Turnaround is 3–4 weeks from Asia; reimbursement outside the US is limited but grant and IIT programs are available. Contact Alex Ngo for country-specific logistics ([email protected])

YoungWha Koh, MD, PhD

Associate Professor, Department of Pathology, Ajou University School of Medicine

“Spatial Profiling of Tertiary Lymphoid Structures in MCC: Proteomic Insights and Future Transcriptomic Directions”

• • Building on multimodal spatial omics findings (Srinivas, Spassova et al., J Immunother Cancer 2025), Dr. Koh outlined four unexplored TLS mechanisms in MCC: (1) MCPyV antibody levels within TLS vs. serum; (2) follicular helper T cell role in TLS; (3) cancer-associated stromal cell contribution to TLS formation; and (4) the aging–TLS axis and immune senescence (shown right: high-plex spatial proteomics of structured TLS in MCC).
  • Elucidating these mechanisms may enable therapeutic TLS modulation to enhance immunotherapy responses—a key frontier for future APAC-led MCC research.