Mark H. O'Hara, MD
Medical Oncology
Accepting new patients
Sees patients age 18 and up
Abramson Cancer Center Perelman 2nd Floor West
Penn Medicine Provider

About me

  • Associate Professor of Medicine (Hematology-Oncology) at the Hospital of the University of Pennsylvania

Education and training

  • Medical School: SUNY Stony Brook School of Medicine
  • Residency: University of Pittsburgh School of Medicine
  • Fellowship: University of Pennsylvania Health System

What my patients think about me

Average Rating

448 reviews

Comments are submitted by patients and reflect their views and opinions. The comments are not endorsed by and do not necessarily reflect the views of Penn Medicine.

Anonymous
March 2026
again he explained everything
Anonymous
March 2026
the doctor explained everything. very thorough
Anonymous
March 2026
smart, high energy, likable doctor, listens to the patient and had answers
Anonymous
February 2026
very happy with this provider

Insurance accepted

My Locations

Penn Medicine hospital privileges

  • Hospital of the University of Pennsylvania: Has privileges to treat patients in the hospital.
Dr. O'Hara is a Penn Medicine physician.

Qualifications and experience

Treatments and Conditions

My research

Khalil DN, Gomez R, Regev A, Samaan F, Marouf Y, Budhu S, Hirschhorn D, Schulze I, Lavery JA, Ceglia N, Freeman SS, Maltez VI, Garcia JM, Suek N, Weng CH, Cabanski CR, Monette S, Romin Y, Li Y, Chaligne R, Yellin MJ, Keler T, Maurer DM, Flamar AL, Morgado-Palacin L, Mangarin LM, Harding JJ, Park W, Lyman JP, Maddock S, O'Hara MH, Abou-Alfa GK, Vonderheide RH, O'Reilly EM, Germain RN, Wolchok JD, Merghoub T. IL-10R inhibition induces neutrophil tumoricidal activity , Cancer Immunol Res: 2026


Till JE, Gal-Rosenberg O, Giliberto SG, Seewald NJ, Ballinger DG, Samberg HE, Yin MR, Wang QL, Cannas S, Kim KN, Tien K, Sawi M, Madineedi V, Furniss CS, Gocheva V, Nowak J, Brais LK, Yuan C, Rosenthal MH, Roses R, DeMatteo R, Lee MK, Vollmer C, Sagreiya H, O'Hara MH, Shemer R, Wolpin B, Dor Y, Carpenter EL. Plasma cell-free DNA markers predict occult metastases in patients with resectable pancreatic ductal adenocarcinoma , Clin Transl Med: 2026


O'Reilly EM, Cabanski CR, Lyman JP, Wainberg ZA, Fisher GA, Wolff RA, Ko AH, O'Hara MH, Spencer CN, Yu JX, Da Silva DM, Padrón LJ, Arnott J, Fairchild J, Moore JS, Peng B, Hoos WA, O'Donnell-Tormey J, Boffo S, Dugan U, Kimmelman AC, Amaravadi RK, Vonderheide RH. Clinical and translational results from a phase 1 trial of gemcitabine/nab-paclitaxel with nivolumab/ipilimumab or hydroxychloroquine/ipilimumab in untreated metastatic pancreatic adenocarcinoma , J Immunother Cancer, 14: 2026,e012864


Barber-Rotenberg JS, Haas AR, Aggarwal C, O'Hara M, Hexner E, Pequignot E, Dowd E, Ndeupen S, Thai E, Chen F, Oner BS, Czuczman C, Gonzalez VE, Fraietta JA, Hwang WT, Chew A, Jadlowsky JK, Marshall A, Shea KM, Jiang Y, Cosey A, Ferthio R, Levine BL, Plesa G, Siegel DL, Young RM, Sheppard NC, Albelda SM, June CH, Tanyi JL. Phase 1 study of autologous T cells bearing fully human chimeric antigen receptors targeting mesothelin in mesothelin-expressing cancers , Mol Ther: 2026


Aznar MA, Good CR, Barber-Rotenberg JS, Agarwal S, Wilson W, Watts A, Zhang Z, Gonzales D, Donahue G, Hwang WT, Rennels AK, Rech AJ, Kuramitsu S, Huang H, Glastad KM, Alexander KA, Plesa G, Dowd E, Brennan A, Siegel DL, Tanyi J, Haas A, Torigian DA, Nadolski G, Gonzalez VE, Hexner EO, Fraietta JA, Jadlowsky JK, Young RM, Berger SL, June CH, O'Hara MH. Clinical and molecular dissection of CAR T cell resistance in pancreatic cancer , Cell Rep Med: 2025


Amit U, Metz JM, Plastaras JP, Gheewala R, Teitelbaum U, Damjanov N, Vollmer C, Schneider CJ, Lee MK 4th, O'Hara M, Reiss-Binder K, Carpenter EL, Karasic TB, Konski A, Wileyto EP, Ben-Josef E. A phase 1 dual-dose escalation study of radiation and nab-paclitaxel in patients with unresectable and borderline resectable pancreatic cancer , Cancer, 131: 2025,e35936


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: 2025,e2515087


Rajdev L, King GG, Lieu CH, Cohen SA, Pant S, Uboha NV, Deming D, Malla M, Kasi A, Klute K, Spencer KR, Dasari A, Morris VK, Botta G, Lowy AM, O'Hara MH, Eads J, King D, Shah MA, Hong TS, Parikh A, Klempner SJ, Jabbour SK, Chawla A, Molena D, George TJ, Gibson MK, Allegra C, Goodman K, Eng C, Philip PA. Incorporating Circulating Tumor DNA Testing Into Clinical Trials: A Position Paper by the National Cancer Institute GI Oncology Circulating Tumor DNA Working Group , JCO Precis Oncol: 2025


Than MT, O'Hara M, Stanger BZ, Reiss KA. KRAS-Driven Tumorigenesis and KRAS-Driven Therapy in Pancreatic Adenocarcinoma. , Molecular Cancer Therapeutics, 23(10): 2024,1378 - 1388


O'Hara MH, Jegede O, Dickson MA, DeMichele AM, Piekarz R, Gray RJ, Wang V, McShane LM, Rubinstein LV, Patton DR, Williams PM, Hamilton SR, Onitilo A, Tricoli JV, Conley BA, Arteaga CL, Harris LN, O'Dwyer PJ, Chen AP, Flaherty KT. Phase 2 Study of Palbociclib in Patients with Tumors with CDK4 or CDK6 Amplification: Results from the NCI-MATCH ECOG-ACRIN Trial (EAY131) Sub-protocol Z1 , Clinical Cancer Research: 2024