Sponsor: Seagen, a wholly owned subsidiary of Pfizer (industry)
Phase: 2
Start date: May 20, 2024
Planned enrollment: 172
Disitamab vedotin (DV; RC48; Aidixi) is a HER2‑directed antibody–drug conjugate (ADC) consisting of the humanized anti‑HER2 antibody hertuzumab linked via a protease‑cleavable mc‑val‑cit‑PABC linker to the microtubule inhibitor monomethyl auristatin E (MMAE). It has shown antitumor activity across multiple HER2‑expressing solid tumors, including urothelial, gastric/gastroesophageal junction (G/GEJ), and breast cancers. DV received its first approval in China in June 2021 for previously treated HER2‑overexpressing G/GEJ cancer. (pmc.ncbi.nlm.nih.gov)
Urothelial carcinoma (UC)
- Phase II pooled analysis (RC48‑C005/C009; HER2‑positive la/mUC after ≥1 prior systemic therapy; n=107):
- ORR 50.5% (95% CI 40.6–60.3) by blinded independent review; median DoR 7.3 months; median PFS 5.9 months; median OS 14.2 months. Activity was seen across subgroups, including those with liver metastases and prior PD‑1/L1 therapy. (pubmed.ncbi.nlm.nih.gov)
- Phase Ib/II combination with toripalimab (RC48‑C014; HER2‑unselected la/mUC; n=41; RP2D DV 2.0 mg/kg q2w + toripalimab 3 mg/kg q2w):
- Confirmed ORR 73.2%; median PFS 9.3 months; median OS 33.1 months (data cutoff March 1, 2024). (pubmed.ncbi.nlm.nih.gov)
- Additional real‑world/retrospective data suggest clinically meaningful activity of DV plus PD‑1 inhibitors in metastatic upper tract UC, with ORR ~59% and median PFS ~13 months (limitations: retrospective design, China‑only cohorts). (pubmed.ncbi.nlm.nih.gov)
Gastric/gastroesophageal junction (G/GEJ) cancer - DV received its first approval in China (June 2021) for previously treated HER2‑overexpressing G/GEJ cancer. (pubmed.ncbi.nlm.nih.gov) - Early‑phase combination studies of DV with PD‑1 inhibitors have reported encouraging activity in HER2‑expressing G/GEJ disease (dose‑escalation/expansion study with toripalimab established RP2D of DV 2.5 mg/kg + toripalimab 3 mg/kg q2w; preliminary efficacy reported). (pubmed.ncbi.nlm.nih.gov) - A multicenter real‑world third‑line‑and‑beyond cohort showed higher ORR and longer PFS with DV plus immune checkpoint inhibitors versus DV alone in HER2‑positive or HER2‑low G/GEJ cancer (ORR 36% vs 10%; median PFS 6.2 vs 3.9 months). (bmccancer.biomedcentral.com)
Breast cancer - Phase I/Ib pooled analysis in advanced breast cancer (HER2‑overexpressing and HER2‑low): at the 2.0 mg/kg q2w dose, confirmed ORR was 42.9% in HER2‑overexpressing and 33.3% in HER2‑low cohorts; median PFS 5.7 and 5.1 months, respectively. (onlinelibrary.wiley.com) - Retrospective real‑world series in previously trastuzumab‑treated metastatic HER2‑positive disease reported ORR 29.6% and median real‑world PFS 5.9 months. (pubmed.ncbi.nlm.nih.gov)
Across trials, the most frequent treatment‑related adverse events (TRAEs) include peripheral sensory neuropathy, hematologic toxicity (neutropenia, leukopenia), and transaminase elevations—generally consistent with MMAE‑based ADCs. In the pooled phase II UC analysis, any‑grade peripheral sensory neuropathy occurred in 68.2% (grade ≥3 in 18.7%); leukopenia in 50.5%; neutropenia in 42.1%. (pubmed.ncbi.nlm.nih.gov)
With DV plus toripalimab in la/mUC (RC48‑C014), common TRAEs were AST increased (65.9%), ALT increased (63.4%), and peripheral sensory neuropathy (63.4%); grade ≥3 TRAEs occurred in 51.2%, and one treatment‑related death (pneumonitis) was reported. (pubmed.ncbi.nlm.nih.gov)
In the phase I/Ib breast cancer program, grade ≥3 events ≥5% included decreased neutrophil count (17.6%), GGT increased (13.2%), asthenia (11.0%), decreased WBC (9.6%); neuropathy events were observed but severe neurotoxicity was uncommon. (onlinelibrary.wiley.com)
Notes: Multiple phase 2/3 programs evaluating DV combinations (often with PD‑1 inhibitors) in UC and G/GEJ cancer are ongoing; emerging data should be interpreted with typical caveats for single‑arm and/or retrospective studies. (pubmed.ncbi.nlm.nih.gov)
Last updated: Oct 2025
Goal: Evaluate the safety, tolerability, dose, and preliminary antitumor activity of disitamab vedotin in combination with tucatinib in HER2-expressing solid tumors, specifically locally advanced or metastatic breast cancer and gastric/gastroesophageal junction adenocarcinoma, and determine an optimal dose for further study before expanding into defined HER2-low and HER2-positive cohorts.
Patients: Adults with measurable, locally advanced unresectable or metastatic breast cancer or gastric/GEJ adenocarcinoma with HER2 expression, ECOG 0–1, and prior progression on or intolerance to standard therapies. Expansion cohorts enroll HER2-low (IHC 1+ or 2+/ISH−) and HER2-positive (IHC 3+ or 2+/ISH+) subtypes in both breast and gastric/GEJ cancers. Key exclusions include prior tucatinib, prior ADCs with an MMAE payload, active CNS or leptomeningeal disease, recent anticancer therapy within 4 weeks, and conditions precluding oral absorption.
Design: Phase 1b/2, open-label, multicenter study with sequential parts: dose escalation of disitamab vedotin plus tucatinib, followed by a randomized dose-optimization phase assessing two DV dose levels for safety and efficacy in HER2-expressing breast and gastric/GEJ cancers, then expansion into four cohorts (HER2-low and HER2-positive for both tumor types). Planned enrollment is 172 participants.
Treatments: Disitamab vedotin plus tucatinib in all phases and cohorts. Disitamab vedotin (RC48) is an anti-HER2 antibody-drug conjugate comprising a humanized anti-HER2 antibody linked via a cleavable vedotin linker to the microtubule inhibitor MMAE. Mechanisms include targeted delivery to HER2-expressing cells, bystander killing, immunogenic cell death, and HER2 signaling inhibition. Clinical data to date show activity across HER2-overexpressing and HER2-low tumors, including objective responses in metastatic breast cancer and approved use in China for HER2-overexpressing gastric cancer after at least two prior lines; common toxicities include peripheral neuropathy, cytopenias, transaminitis, and fatigue. Tucatinib is an orally administered, selective HER2 tyrosine kinase inhibitor approved in combination regimens for HER2-positive breast cancer, including in patients with brain metastases.
Outcomes: Primary: safety and tolerability measures including laboratory abnormalities, adverse events, dose-limiting toxicities in escalation, and frequency of dose modifications; objective response rate by investigator per RECIST v1.1 in later phases. Secondary: duration of response, disease control rate, progression-free survival, overall survival, pharmacokinetics (Cmax, AUClast), and incidence of anti-drug antibodies to disitamab vedotin.
Burden on patient: Moderate to high. As a Phase 1b/2 combination study with dose escalation and pharmacokinetics, participants can expect intensive early-cycle visits with frequent labs, AE monitoring, and serial PK blood draws. Imaging per RECIST at regular intervals will require travel for scans. Disitamab vedotin is administered intravenously, adding infusion time and potential premedications, while tucatinib is oral and requires adherence and monitoring for hepatic toxicity and diarrhea. Some cohorts require provision of archival or new tumor tissue, which may necessitate a biopsy if archival tissue is insufficient. The open-label design and multi-year follow-up for survival and safety extend visit frequency and monitoring beyond standard care in later lines of therapy.
Last updated: Oct 2025
Inclusion Criteria:
General Inclusion Criteria
* Measurable disease according to RECIST v1.1
* Eastern Cooperative Oncology Group (ECOG) Performance Status score of 0 or 1
Dose Escalation and Optimization Phase Inclusion Criteria
* Histologically or cytologically confirmed diagnosis of gastric or gastroesophageal junction adenocarcinoma or breast carcinoma
* Locally-advanced, unresectable, or metastatic stage
* Must have experienced disease progression on or after standard of care therapies or be intolerant of standard of care therapies.
Cohort A (HER2-Low Breast Cancer) Inclusion Criteria
* Histologically or cytologically confirmed diagnosis of breast carcinoma
* Locally-advanced, unresectable, or metastatic stage
* HER2-low status determined by most recent local assessment (IHC 1+ or IHC 2+/ISH-negative)
* Prior therapies requirements
* No more than 3 prior systemic cytotoxic chemotherapy regimens (including ADCs) for LA/mBC.
* Participants with known BRCA mutation must have received a PARP-inhibitor where available and not medically contraindicated
* Have progression on or after, or intolerant to, T-DXd, sacituzumab govitecan, or other topoisomerase I inhibitor therapies, if available as local standard of care therapy
* Participants with HR+ tumors must have intolerance to endocrine therapy or endocrine therapy refractory disease:
* Progressed on ≥2 lines of endocrine therapy for LA/mBC AND had received a CDK4/6 inhibitor in the adjuvant or metastatic setting OR
* Progressed on 1 line of endocrine therapy for LA/mBC AND had a relapse while on adjuvant endocrine therapy after definitive surgery for primary tumor AND had received a CDK4/6 inhibitor in the adjuvant or advanced setting
* Participants with HR negative, HER2-low and PD-L1-positive (CPS 10 or greater) tumors must have received pembrolizumab with chemotherapy if available as local standard of care therapy.
* Participants with HR negative, HER2-low and PD-L1-positive (CPS 10 or greater) tumors must have received pembrolizumab (or other PD-(L)1 inhibitor) with chemotherapy if available as local standard of care therapy and not medically contraindicated.
Cohort B (HER2+ Breast Cancer) Inclusion Criteria
* Histologically or cytologically confirmed diagnosis breast carcinoma
* Locally-advanced, unresectable, or metastatic stage
* HER2+ status determined by most recent local assessment (IHC 3+ or IHC 2+/ISH+)
* Participants must have:
* Received prior trastuzumab, pertuzumab and a taxane if available as local standard of care therapy for advanced disease.
* Have progression on or after, or intolerant to, T-DXd or other topoisomerase I inhibitor therapies
* No more than 3 prior systemic cytotoxic chemotherapy regimens (including ADCs) for LA/mBC
Cohort C (HER2-Low Gastric or Gastroesophageal Junction Adenocarcinoma) Inclusion Criteria
* Histologically or cytologically confirmed diagnosis of gastric or gastroesophageal junction adenocarcinoma
* Locally-advanced, unresectable, or metastatic stage
* HER2-low expression defined as IHC 1+ or IHC 2+/ISH-negative determined by most recent local assessment
* Willing and able to provide archival or newly obtained formalin-fixed paraffin-embedded (FFPE) tumor tissue blocks
* Participants must have received:
* Prior systemic therapy with platinum, fluorouracil, or taxane for locally advanced unresectable or metastatic disease
* Progression within 6 months of last dose of (neo)adjuvant cytotoxic chemotherapy is considered as 1 line of systemic therapy for LA/mGC/GEJC
* Prior anti-PD-(L)1 therapy is allowed
* No more than 2 prior systemic cytotoxic chemotherapy regimens (including ADC) for LA/mGC/GEJC
* Must not have received prior treatment with HER2 directed therapy
Cohort D (HER2+ LA/mGC/GEJC) Inclusion Criteria
* Histologically or cytologically confirmed diagnosis of gastric or gastroesophageal junction adenocarcinoma
* Locally-advanced, unresectable, or metastatic stage
* HER2+ status determined by most recent local assessment (IHC 3+ or IHC 2+/ISH+)
* Participants must have:
* Received prior trastuzumab plus fluoropyrimidine and platinum containing chemotherapy if no contraindication.
* Prior T-DXd treatment is allowed
* Prior PD1 inhibitor therapy is allowed
* No more than 2 prior systemic cytotoxic chemotherapy regimens (including ADCs) for LA/mGC/GEJC
Exclusion Criteria:
* Known hypersensitivity to any excipient contained in the drug formulation of disitamab vedotin or tucatinib
* Prior therapy with ADCs with MMAE payload
* Prior therapy with tucatinib
* Active CNS and/or leptomeningeal metastasis.
* Participants who have received prior systemic anticancer treatment including investigational agents within 4 weeks prior to first dose of study treatment
* History of other invasive malignancy within 3 years before the first dose of study intervention, or any evidence of residual disease from a previously diagnosed malignancy.
* Unable to swallow oral tablets or capsules or any significant GI disease which would preclude the adequate oral absorption of medications
Kelowna, British Columbia, V1Y 5L3, Canada
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Ottawa, Ontario, K1H 8L6, Canada
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Toronto, Ontario, M4N 3M5, Canada
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Toronto, Ontario, M5G 2M9, Canada
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München, 81675, Germany
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Essen, 45147, Germany
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Heidelberg, 69120, Germany
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Milan, Lombardy, 20141, Italy
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Seoul, 02841, South Korea
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Seongnam-si, 463-707, South Korea
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Seoul, 3722, South Korea
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Goyang-si, Other, 10408, South Korea
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Barcelona, 08950, Spain
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Valencia, 46004, Spain
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Madrid, 28050, Spain
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Valencia, 46010, Spain
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Barcelona, 08035, Spain
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L'Hospitalet de Llobregat, 08908, Spain
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Barcelona, 08023, Spain
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Madrid, 28050, Spain
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London, SW3 6JJ, United Kingdom
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London, SW3 6JJ, United Kingdom
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Sutton, Surrey, SM2 5PT, United Kingdom
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Tucson, Arizona, 85719, United States
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Tucson, Arizona, 85704, United States
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Tucson, Arizona, 85724, United States
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Tucson, Arizona, 85719, United States
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Tucson, Arizona, 85719, United States
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Orange, California, 92868, United States
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Orange, California, 92868, United States
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Santa Monica, California, 90504, United States
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San Francisco, California, 94158, United States
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Grand Junction, Colorado, 81505, United States
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Grand Junction, Colorado, 81505, United States
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Danbury, Connecticut, 06810, United States
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Norwalk, Connecticut, 06856, United States
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Washington D.C., District of Columbia, 20007, United States
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Washington D.C., District of Columbia, 20007, United States
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Tampa, Florida, 33612, United States
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Tampa, Florida, 33607, United States
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Tampa, Florida, 33612, United States
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Wesley Chapel, Florida, 33544, United States
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Tampa, Florida, 33612, United States
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Atlanta, Georgia, 30342, United States
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Cumming, Georgia, 30041, United States
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Atlanta, Georgia, 30341, United States
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Athens, Georgia, 30606, United States
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Blairsville, Georgia, 30512, United States
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Canton, Georgia, 30115, United States
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Cumming, Georgia, 30041, United States
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Decatur, Georgia, 30033, United States
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Macon, Georgia, 31217, United States
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Marietta, Georgia, 30060, United States
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Atlanta, Georgia, 30342, United States
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Atlanta, Georgia, 30342, United States
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Atlanta, Georgia, 30342, United States
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Duluth, Georgia, 30096, United States
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Lawrenceville, Georgia, 30046, United States
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Shiloh, Illinois, 62269, United States
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Shiloh, Illinois, 62269, United States
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Boston, Massachusetts, 02215, United States
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Boston, Massachusetts, 02215, United States
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Newton, Massachusetts, 02459, United States
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Boston, Massachusetts, 02114, United States
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St Louis, Missouri, 63110, United States
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Kansas City, Missouri, 64111, United States
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Kansas City, Missouri, 64111, United States
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Florissant, Missouri, 63031, United States
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St Louis, Missouri, 63129, United States
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City of Saint Peters, Missouri, 63376, United States
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Creve Coeur, Missouri, 63141, United States
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Kansas City, Missouri, 64111, United States
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St Louis, Missouri, 63110, United States
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St Louis, Missouri, 63110, United States
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Reno, Nevada, 89502, United States
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New York, New York, 10065, United States
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Columbus, Ohio, 43219, United States
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Greenville, South Carolina, 29607, United States
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Nashville, Tennessee, 37203, United States
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Nashville, Tennessee, 37203, United States
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Nashville, Tennessee, 37203, United States
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Dallas, Texas, 75235, United States
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Dallas, Texas, 75390, United States
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Dallas, Texas, 75235, United States
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Dallas, Texas, 75390, United States
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Dallas, Texas, 75237, United States
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Richardson, Texas, 75080, United States
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Dallas, Texas, 75235, United States
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Dallas, Texas, 75390, United States
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Fort Worth, Texas, 76104, United States
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Seattle, Washington, 98109, United States
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Seattle, Washington, 98104, United States
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Seattle, Washington, 98195, United States
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Madison, Wisconsin, 53792, United States
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Madison, Wisconsin, 53718, United States
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Frankston, Australia
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Frankston, Victoria, 3199, Australia
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Mount Waverley, Victoria, 3149, Australia
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Frankston, Victoria, 3199, Australia
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Berlin, 12203, Germany
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Napoli, 80131, Italy
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Napoli, Campania, 80131, Italy
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Napoli, Campania, 80131, Italy
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Napoli, Campania, 80131, Italy
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Milan, Lombardy, 20162, Italy
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Misterbianco (CT), Sicily, 95045, Italy
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Verona, Veneto, 37134, Italy
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Cheongju-si, 28644, South Korea
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Incheon, 21565, South Korea
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Seoul, 06351, South Korea
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Seoul, 110-744, South Korea
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Suwon, 16247, South Korea
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Busan, Other, 49201, South Korea
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Erandio Bizkaia, 48950, Spain
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Bilbao, 48013, Spain
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Taoyuan, 333, Taiwan
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Tainan City, 704017, Taiwan
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Tainan City, 704, Taiwan
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Taipei, 106, Taiwan
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Taipei, 100225, Taiwan
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Taipei, 100, Taiwan
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London, EC1M 6BQ, United Kingdom
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Manchester, M20 4GJ, United Kingdom
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Sutton, SM2 5PT, United Kingdom
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Farmington, New Mexico, 87401, United States
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Status: TERMINATED