Leadership Team

Yujiro S. Hata

Chief Executive Officer

Yujiro is an entrepreneur with over 20 years of experience building companies that have delivered innovative therapies to patients. In August 2015, he launched IDEAYA Biosciences as its first employee and Chief Executive Officer. From 2014 to August 2015, he served as Chief Operating Officer at Flexus Biosciences and FLX Bio, which he joined as a startup and led through its acquisition by Bristol-Myers Squibb in April 2015. From 2010 through the approvals of Kyprolis® and Stivarga® and its acquisition by Amgen in October 2013, he was Vice President, Corporate Development and Strategy at Onyx Pharmaceuticals (NASDAQ: ONXX), where he served as Head of Strategy and Strategic Asset Management, and Head of Transactions. From 2002 to 2010, Yujiro served as Vice President, Senior Vice President, and Chief Business Officer at Enanta Pharmaceuticals (NASDAQ: ENTA), which he joined as a startup and helped build to a public company that discovered the protease inhibitors contained in Viekira Pak and Mavyret™, both of which received Breakthrough Therapy designation by the U.S. FDA. He earlier served in roles at McKinsey, ImClone and Columbia Medical School.

Yujiro obtained his MBA at Wharton as a Henry J Kaiser recipient and did undergraduate studies at Oxford University and Colorado College. He is an Executive-in-Residence at 5AM Ventures, serves on the Board of Directors at Xencor (NASDAQ: XNCR) and Expansion Therapeutics, and Board of Visitors at the UCSD Cancer Center.

Michael P. Dillon, Ph.D.

Senior Vice President and Chief Scientific Officer, Head of Research

Mike brings over 20 years of experience in drug discovery. He joined IDEAYA Biosciences as Senior Vice President, Head of Drug Discovery in April 2016, and has served as Senior Vice President and Chief Scientific Officer, Head of Research since February 2018. From 2008 to 2016, Mike was with the Novartis Institutes for Biomedical Research (NIBR) where he served in various leadership roles, including Global Discovery Chemistry Head, Oncology and New Therapeutic Modalities; Head of Chemical Sciences, Emeryville, and Executive Director Oncology Chemistry. Under his leadership at NIBR, several small molecules were advanced towards the clinic, including, PI3K inhibitor BKM120, CSF1R inhibitor BLZ945, V600E mutant B-RAF kinase inhibitor Encorafenib, PIM kinase inhibitor PIM447, ERK inhibitor LTT462, and RAF kinase inhibitor LXH254. From 1993 to 2008, Mike worked at Roche and Syntex (acquired by Roche), where he served in roles of increasing responsibility, including Director, Medicinal Chemistry. At Roche, he led multiple small molecule programs that advanced to the clinic, including first-in-class P2X3 antagonist Gefapixant, now being developed by Merck. Mike is an author on over 60 publications and patents.

Mike obtained his B.Sc. (Hons) from the University of Leicester, and his Ph.D. in Chemistry from the University of Bristol. He completed his postdoctoral fellowship at Oregon State University to continue his research in Chemistry with Professor James D. White.

Julie Hambleton, M.D.

Senior Vice President and Chief Medical Officer, Head of Development

Julie is a senior biotechnology executive with over 20 years of experience in clinical drug development from pre-clinical through phase 4 and post-marketing studies. She has extensive experience working with regulatory agencies, including the U.S. FDA and the European Medicines Agency (EMA), and in filings of INDs, biologics license applications (BLAs), and special protocol assessments (SPAs). Julie was previously Vice President, Head of US Medical at Bristol-Myers Squibb (NYSE: BMY), overseeing Medical & Health Economic and Outcomes Research activities in support of the Oncology, Immuno-Oncology, Specialty and Cardiovascular marketed portfolios. From 2012 to 2016, she was Executive Vice President and Chief Medical Officer at Five Prime Therapeutics (NASDAQ: FPRX), where she led Clinical, Clinical Operations, Regulatory, Preclinical and Translational and Process Development and was a member of the Executive Committee. From 2010 to 2012, Julie was Vice President, Clinical Development, at Clovis Oncology (NASDAQ: CLVS), where she oversaw clinical development programs and managed Clinical and Pharmacokinetic functions, including the development of Rubraca®, a PARP inhibitor, developed with a diagnostic for BRCA and HRD. From 2003 to 2010, she was at Genentech, most recently as Group Medical Director, Global Clinical Development, leading a cross-functional group conducting Phase 2 and 3 trials of Avastin®.

Julie completed her medical and hematology-oncology training at the University of California, San Francisco, where she then served on faculty from 1993 to 2003. She received a B.S. from Duke University, and M.D. from Case Western Reserve University School of Medicine and was Board-certified in Hematology and Internal Medicine.

Jeffrey Hager, Ph.D.

Senior Vice President and Chief Technology Officer, Head of Target Discovery and External Innovation

Jeff has over 20-years of experience in tumor biology, cancer pharmacology, & oncology discovery. He is co-founder and Senior Vice President and Chief Technology Officer and Head of Target Discovery and External Innovation at IDEAYA Biosciences. Prior to that he was Senior Vice President and Head of Biology at IDEAYA. Before his involvement with IDEAYA, he was VP of Biology at Seragon Pharmaceuticals, which was acquired by Roche/Genentech, where he oversaw all in vitro and in vivo biology and pharmacology that lead to the discovery of 2 novel, clinical stage selective estrogen receptor degraders (SERDs) developed as treatment for hormone receptor positive breast cancer. Previously, Jeff was Senior Director at Aragon Pharmaceuticals which was acquired by Johnson & Johnson. At Aragon, his team was central in pre-clinical development of the novel anti-androgen apalutamide (Erleada), an FDA approved treatment for early-stage castration resistant prostate cancer. Previously, he was Associate Director of Biology at Apoptos, Inc. and before that a Principal Scientist and Head of Cancer Pharmacology at Kalypsys, Inc.

He did graduate studies at Princeton and University of California at Berkeley, the later from which he received a PhD in molecular and cell biology. He was a postdoctoral fellow and staff scientist at the University of California at San Francisco and is an author of publications in Annual Review of Cancer Biology, eLife, Science, Nature Genetics, Cancer Cell, Cancer Research and Cancer Discovery.

Paul A. Stone, J.D.

Senior Vice President, General Counsel and Head of Operations

Paul is a life science executive with over 20 years of legal, financial, and management experience. Paul was previously with 5AM Ventures for over nine years in various leadership capacities including as Partner, General Counsel, and Chief Operating Officer. Paul serves as a Board of Director of Scientist and was a founding Board of Director at Cidara (NASDAQ: CDTX), Homology, IDEAYA and Metchnikoff, as well was a Board Observer at RareCyte and other companies. He also held early management and operating rolls at Entrada, Cidara, and Homology. Prior to joining 5AM, Paul was Senior Vice President and General Counsel at Ethos Pharmaceuticals, Senior Vice President, General Counsel and Chief Patent Counsel at Ilypsa (acquired by Amgen) and Vice President, Chief Patent Counsel at Symyx (IPO). He earlier served in roles at Boeing and Wisconsin Electric.

Paul earned a B.S. in Chemical Engineering, University of Wisconsin, Madison, after which he served as a U.S. Naval Officer on USS NIMITZ. He received a J.D. from University of Wisconsin Law School and practiced intellectual property law as a Patent Attorney at Senniger Powers. Paul taught patent law, trade secrets law and licensing as an adjunct professor at University of Missouri and Santa Clara University. He also served on the Board of Directors of a regional non-profit, Save the Bay.

Tim Smith

Senior Vice President, Head of Corporate Development

Tim has more than 15 years of experience in the life sciences industry, consisting primarily of roles in equity research, investor relations, and business development. Tim joined IDEAYA from Cleave Biosciences, where he was chief business officer. Prior to Cleave, he was executive director, business development at Celgene Corporation. In this role, he led numerous M&A, in-licensing and strategic equity investment transactions, including the acquisition of Receptos, Inc. and the strategic collaboration with Jounce Therapeutics. Tim joined Celgene in 2009 as director, investor relations and subsequently led the business planning and analysis function. Prior to joining Celgene, he was director, investor relations at MGI PHARMA, Inc. He spent the majority of his early career in equity research covering the biotechnology sector at RBC Capital Markets, Lazard Capital Markets and Citi Research. He began his career as a research technician at the Skirball Institute of Biomolecular Medicine.

Tim holds a B.S. in biology from the University of Texas at Arlington, an M.B.A. in finance from Fordham University and an M.A. in biotechnology from Columbia University.

Andres Ruiz Briseno, C.P.A.


Andres joined the IDEAYA Biosciences team as its Controller in August 2016 and has over 8 years of progressive accounting and finance experience for public and private life science companies. Prior to joining IDEAYA, Andres served as Associate Director of Financial Planning & Analysis at Pharmacyclics, Inc., where he helped lead the organization’s finance and operations efforts in support of the successful launch of blockbuster cancer drug, IMBRUVICA® (ibrutinib). He also played a vital role in building the Company’s long-range planning and the integration activities into AbbVie, following Pharmacyclics’ $21 billion acquisition. Previously, Andres held roles at Theravance, Inc. and at PricewaterhouseCoopers’ assurance practice where he focused on life science and venture capital clients.

Andres obtained his B.S. in Business Administration with a concentration in Corporate Financial Management from San Jose State University and is a Certified Public Accountant, licensed in the state of California.