William Joseph Chapin, MD, MSCE
Assistant Professor of Medicine (Hematology-Oncology) at the Hospital of the University of Pennsylvania
Department: Medicine
Contact information
Perelman Center for Advanced Medicine
10 South Pavilion
3400 Civic Center Blvd
Philadelphia, PA 19104
10 South Pavilion
3400 Civic Center Blvd
Philadelphia, PA 19104
Education:
BS (Molecular Biology, Spanish, Honors in the Liberal Arts)
University of Wisconsin-Madison , 2012.
MD (Medicine )
The University of Chicago Pritzeker School of Medicine , 2016.
MSCE (Clinical Epidemiology)
University of Pennsylvania Perelman School of Medicine , 2022.
Permanent linkBS (Molecular Biology, Spanish, Honors in the Liberal Arts)
University of Wisconsin-Madison , 2012.
MD (Medicine )
The University of Chicago Pritzeker School of Medicine , 2016.
MSCE (Clinical Epidemiology)
University of Pennsylvania Perelman School of Medicine , 2022.
Selected Publications
O'Connor S, Seewald N, Chapin WJ, Doucette A, Blaha C, Reiss KA. : Evaluation of the impact of GLP-1 receptor agonists (RAs) on stage of PDAC diagnosis: A retrospective matched cohort study. American Society of Clinical Oncology Annual Meeting, Chicago, IL. J Clin Oncol, 44, Jun 2026.Morris II VK, Colby S, Kopetz S, Guthrie KA, Chapin WJ, Breakstone R, Hu ZI, Fakih M, Gholami S, Gold PJ, Chiorean EG, Philip PA.: SWOG S2107: Randomized phase II trial of encorafenib and cetuximab with or without nivolumab for patients with previously treated MSS, BRAFV600E metastatic colorectal cancer (mCRC). American Society of Clinical Oncology Annual Meeting, Chicago, IL. J Clin Oncol, 44, Jun 2026 Notes: "Oral Presentation"
Chapin WJ, Cenou N, Delman D, Eads JR, Manley M, Reiss KA, Sackey M, Teitelbaum UR, Walsh J, Beatty GL, O'Hara MH.: Phase II trial of pembrolizumab in combination with odetiglucan for patients with metastatic colorectal adenocarcinoma with liver-predominant disease. American Society of Clinical Oncology Annual Meeting, Chicago, IL. J Clin Oncol, 44, Jun 2026 Notes: "Poster Presentation"
Boursi B, Stemmer A, Chapin WJ, Shacham-Shmueli E, Kopetz S, Andre T, Overman MJ, Pietrantonio F, Margalit O. : Durable responses to immunotherapy in dMMR/MSI-H metastatic colorectal cancer patients with poor performance status. American Society of Clinical Oncology Annual Gastrointestinal Meeting, San Francisco, CA. Jan 2026 Notes: "Poster Presentation"
Kim RD, Saeed A, Chapin WJ, Kim K, Iyer R, Martin II RC, Grothey A, Gadde S, Feun LG, Gabayan A, Saenger YM, Abdelrahim M, Govada N, Xie B, Cho M, Burgoyne A.: A multicenter, open-label study of RP2 oncolytic immunotherapy expressing anti–CTLA-4 in combination with second-line atezolizumab plus bevacizumab in advanced hepatocellular carcinoma (HCC) or in combination with first-line durvalumab in advanced biliary tract cancer (BTC). American Society of Clinical Oncology Annual Gastrointestinal Meeting, San Francisco, CA. Jan 2026 Notes: "Poster Presentation"
Boursi B, Kolkey ZL, Reiss KA, O'Hara MH, Chapin WJ. : Comparative effectiveness of oxaliplatin or irinotecan rechallenge vs standard third-line therapies in patients with metastatic colorectal cancer. American Society of Clinical Oncology Annual Gastrointestinal Meeting, San Francisco, CA. Jan 2026 Notes: "Poster Presentation"
Lin JK, Niu J, Giordano SH, Li P, Snyder RA, Liao K, Li M, Aparicio A, Chapin W, Zhang J, Xiang J, Perera N, Pain D, Guerra CE, Doshi JA.: Racial and Ethnic Disparities Along the Treatment Cascade Among Medicare Fee-for-Service Beneficiaries With Metastatic Breast, Colorectal, Lung, and Prostate Cancers. J Clin Oncol Aug 2025.
Swami N, Hwang WT, Mamtani R, O'Hara MH, Chapin WJ.: Second-Line Treatment Strategies for Right-Sided, RAS/RAF Wild-Type Colorectal Cancer. JAMA Netw Open 8: e2515087, Jun 2025.
Swami N, Hwang WT, O’Hara MH, Chapin WJ. : Real-world evaluation of a “hyperselection” predictive biomarker for anti-EGFR therapy benefit in patients with RAS/RAF wild-type, MMRp/MSS mCRC. J Clin Oncol 43(16), May 2025.
Nishwant Swami , Wei-Ting Hwang , Ronac Mamtani , Mark O'Hara , William Chapin: Real-world survival comparison of second-line treatment strategies for patients with RAS/RAF wild-type, right-sided metastatic colorectal cancer. Journal of Clinical Oncology 43(4_suppl): 73, Jan 2025.