Antoni Ribas, MD
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Antoni Ribas, MD

  • Cutaneous (Skin) Medical Oncology
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Westwood Cancer Care | 100 Medical Plaza, Suite 550, Los Angeles, CA 90095


Antoni Ribas, MD, PhD, is professor of medicine, surgery, and molecular and medical pharmacology at the University of California Los Angeles (UCLA), director of the Tumor Immunology Program at the Jonsson Comprehensive Cancer Center (JCCC) and director of the Parker Institute for Cancer Immunotherapy (PICI) Center at UCLA.

His research is focused on laboratory and clinical studies to address primary and acquired resistance to immunotherapy and targeted therapies for melanoma, and in the development of gene-engineered adoptive T cell transfer therapies for cancer. He has been instrumental in the clinical development of several agents approved by the FDA, including the first anti-PD-1 pembrolizumab (Keytruda), two combinations of BRAF and MEK inhibitors vemurafenib (Zelboraf) and cobimetinib (Cotellic), dabrafenib (Tafinlar) and trametinib (Mekinist), and was involved in the development of the first CD19 CAR for lymphoma axicabtagene ciloleucel (Yescarta). He is a past president of the American Association for Cancer Research (AACR), an elected Fellow of the AACR Academy, the Royal Academy of Medicine of Catalonia, the American Society of Clinical Investigation, and the National Academy of Medicine.


English, Spanish, Catalan



Hematology/Oncology, UCLA School of Medicine, 2001
Surgical Oncology, UCLA School of Medicine, 1998


Hospital Vall d'Hebron, 1994


Medical Oncology, Hospital Vall d'Hebron, 1991


MD, Universidad de Barcelona, 1990

Hospital Affiliations

Ronald Reagan UCLA Medical Center

UCLA Santa Monica Medical Center

Medical Services



As a physician-scientist, Dr. Ribas conducts clinical and laboratory research to advance the treatment of patients with melanoma. In his NIH and California State-funded laboratory he conducts research focusing on mechanisms of response and resistance to cancer immunotherapies and targeted therapies for melanoma, and studies the development of novel adoptive cell transfer therapies with engineered T lymphocytes.


Selected Publications:

  1. Mark E. Davis, Jonathan E. Zuckerman, Chung Hang J. Choi… Antoni Ribas. Evidence of RNAi in humans from systemically administered siRNA via targeted nanoparticles. Nature 2010 Apr 15; 464 (7291): 1067-70.
  2. Fei Su, Amaya Viros, Carla Milagre… Antoni Ribas*, Richard Marais*. RAS mutations in cutaneous squamous cell carcinomas with BRAF inhibitors. *equal contribution as corresponding and senior authors. New England Journal of Medicine 2012 January 19; 366: 207-15.
  3. Jeffrey A. Sosman, Kevin B. Kim, Lynn Schuchter… Antoni Ribas. Survival in BRAF V600-mutant advanced melanoma treated with vemurafenib. New England Journal of Medicine 2012 Feb 23; 366 (8): 707-14.
  4. Omid Hamid, Caroline Robert, Adil Daud… Antoni Ribas. Safety and Tumor Responses with Lambrolizumab (Anti PD-1) in Melanoma. New England Journal of Medicine 2013 Jul 11; 369 (2): 134-44.
  5. Caroline Robert*, Antoni Ribas*, Jedd D. Wolchok… Adil Daud. *equal contribution. Anti–PD-1 Treatment with MK-3475 in Ipilimumab-Refractory Advanced Melanoma. The Lancet 2014 Sep 20; 384 (9948): 1109-17
  6. James Larkin, Paolo A. Ascierto, Brigette Dréno… Antoni Ribas. Combined vemurafenib and cobimetinib in BRAF-mutated melanoma. New England Journal of Medicine 2014 Nov 13; 371 (20): 1867-76.
  7. Paul C. Tumeh, Christina L. Harview, Jennifer H. Yearley… Antoni Ribas. PD-1 blockade induces responses by inhibiting adaptive immune resistance. Nature 2014 Nov 26; 515 (7528): 568-71
  8. Caroline Robert, Jacob Schachter, Georgina V. Long… Antoni Ribas. Pembrolizumab versus ipilimumab in advanced melanoma. New England Journal of Medicine 2015 Jun 25; 372 (26): 2521-32.
  9. Antoni Ribas, Omid Hamid, Adil Daud… Caroline Robert. Association of Pembrolizumab Administration with Tumor Response and Survival Among Patients with Advanced Melanoma. Journal of the American Medical Association (JAMA) 2016 Apr 19; 315 (15): 1600-9.
  10. Jesse M. Zaretsky, Angel Garcia Diaz, Daniel Sanghoon Shin… Antoni Ribas. Mutations associated with acquired resistance to PD-1 blockade in melanoma. New England Journal of Medicine 2016 Sep; 375 (9): 819-29. 
  11. Daniel Sanghoon Shin, Jesse M. Zaretsky, Helena Escuin-Ordinas… Antoni Ribas. Primary resistance to PD-1 blockade mediated by JAK1/2 mutations. Cancer Discovery 2017 Feb; 7 (2): 188-201.
  12. Antoni Ribas, Reinhard Dummer, Igor Puzanov… Georgina V. Long. Oncolytic Virotherapy to Reverse Absence of Intratumoral T-Cell Infiltration and Improve Anti‒PD-1 Immunotherapy. Cell 2017 Sep 7; 170 (6): 1109-1119.e10.
  13. Zeynep Eroglu, Jesse M. Zaretsky, Siwen Hu-Lieskovan… Antoni Ribas. High response rate to PD-1 blockade in desmoplastic melanomas. Nature 2018 Jan 18; 553 (7688): 347-350.
  14. Antoni Ribas, Donald Lawrence, Victoria Atkinson… Omid Hamid. Combined BRAF and MEK inhibition with PD-1 blockade immunotherapy in BRAF-mutant melanoma. Nature Medicine 2019 Jun; 25 (6): 936-940.
  15. Gabriel Abril-Rodríguez, Davis Y. Torrejon, Wei Liu… Antoni Ribas. PAK4 inhibition improves PD-1 blockade immunotherapy. Nature Cancer 2020 Jan, 1 (2): 46–58.
  16. Davis Y. Torrejon, Gabriel Abril-Rodriguez, Ameya Champhekar… Antoni Ribas. Overcoming genetically-based resistance mechanisms to PD-1 blockade. Cancer Discovery 2020 Aug; 10 (8): 1140-1157.
  17. Catherine S. Grasso, Jennifer Tsoi, Mykola Onyshchenko… Antoni Ribas. Conserved Interferon-γ Signaling Drives Clinical Response to Immune Checkpoint Blockade Therapy in Melanoma. Cancer Cell 2020 Sep 8: S1535-6108 (20) 30416-5.
  18. Alain P. Algazi, Megan Othus, Adil I. Daud… Antoni Ribas. Continuous compared to intermittent dabrafenib and trametinib in BRAF mutated melanoma. Nature Medicine 2020 Oct; 26 (10): 1564-1568.

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  • NCI R35 Outstanding Investigator Award, 2022
  • Doctor Honoris Causa from the Free University of Brussels (Vrije Universiteit Brussel), 2021
  • Lifetime Achievement Award from the Society for Melanoma Research (SMR), 2021
  • Elected member of the National Academy of Medicine (NAM), 2020
  • Fellow of the AACR Academ, 2020
  • ESMO Award for Translational Research, 2020
  • Award of Excellence in Medicine, Hope Funds for Cancer Research, 2019
  • William B. Coley Award in Basic and Tumor Immunology, Cancer Research Institute (CRI), 2019
  • Agilent Thought Leader Award, 2019
  • AACR-CRI Lloyd J. Old Award in Cancer Immunology, 2018
  • Ranked #12 of the 2017’s Highly Cited Researchers of any field by Clarivate Web of Science, 2017
  • Doctor Honoris Cause from the University of Buenos Aires, Argentina, 2017
  • AACR Richard and Hinda Rosenthal Memorial Award, 2016
  • Member of the Royal Academy of Medicine of Catalonia, 2015
  • Lila and Murray Gruber Memorial Cancer Research Award and Lectureship, American Academy of Dermatology (AAD), 2015
  • Giants of Cancer Award, OncLife, 2015
  • R35 Outstanding Researcher Award, NIH-NCI, 2015
  • Outstanding Research Award, Society for Melanoma Research (SMR), 2013
  • Physician of the Year, Melanoma International Foundation, 2013
  • Elected member of the American Society of Clinical Investigation (ASCI), 2009
  • New Faculty Award from the California Institute of Regenerative Medicine (CIRM), 2008
  • Melanoma Research Foundation Junior Researcher Award, 2005
  • Stop Cancer Career Development Award, 2002
  • K23 CA93376 Career Development Award, 2002
  • Clinical Research Career Development Award from the American Society of Clinical Oncology (ASCO), 2000
  • Amgen Oncology Fellow Award. 2000 Fellow Teaching Award, UCLA, 2000
  • Extraordinary Prize and Suma Cum Laude, Doctoral Thesis. Autonomous University of Barcelona, 1997