Our story is in our name


Halda means “to hold” in old Nordic languages.  It represents the way that Halda’s novel therapeutic mechanism holds two proteins together in a tightly regulated manner, resulting in cancer-targeted loss of a function essential to cell survival.

To take hold of our vision, we are discovering and developing RIPTAC (Regulated Induced Proximity TArgeting Chimeras) therapeutics that work by a novel hold and kill mechanism for the precision treatment of cancer. RIPTAC therapeutics are innovative heterobifunctional small molecules that hold together two proteins, a cancer-specific protein and a protein with essential function, resulting in abrogation of the essential cell function, and subsequently, cancer cell death.

The novel mode of action of RIPTAC therapeutics is designed to overcome the known bypass mechanisms of resistance that evolve during treatment, a common limitation of today’s precision oncology medicines. We have built a robust technology platform with a portfolio of RIPTAC therapeutics, including our two most advanced programs in major solid tumors, to address unmet need within drug resistant patients.

Our leadership team has deep expertise in bifunctional drug discovery, platform innovation, and company building. We are located in New Haven, CT.

Leadership team

Craig Crews, PhD


Dr. Craig Crews is the John C. Malone Professor of MCDB and professor of Chemistry and Pharmacology at Yale University. A serial entrepreneur, he co-founded Proteolix, Inc., in 2003 whose proteasome inhibitor, Kyprolis™ received FDA approval for the treatment of multiple myeloma. Dr. Crews’ lab is also credited with founding the field of ‘Targeted Protein Degradation’ drug development technology, i.e., PROTACs®, which has the potential to target currently ‘undruggable’ disease causing proteins. In 2013, Dr. Crews launched the biotech company, Arvinas, Inc., that is advancing the first PROTAC-based drugs in clinical trials for several types of cancer. Dr. Crews also founded Halda Therapeutics, a venture-backed biotech company that is developing RIPTAC therapeutics to target cancer cells selectively and create a new drug modality for life changing therapeutics for cancer patients. In 2021, Dr. Crews founded Siduma Therapeutics to advance other novel heterobifunctional concepts with broad utility in drug development.

Dr. Crews graduated from the University of Virginia with a B.A. in Chemistry and received his Ph.D. from Harvard University in Biochemistry. On the faculty at Yale since 1995, his laboratory has developed the use of small molecules to control intracellular protein levels. In 2003, Dr. Crews has received numerous awards and honors, including the Ehrlich Award for Medicinal Chemistry (2014), a NIH R35 Outstanding Investigator Award (2015), the AACR Award for Outstanding Achievement in Chemistry in Cancer Research (2017), the Khorana Prize from the Royal Society of Chemistry (2018), the Pierre Fabre Award for Therapeutic Innovation (2018), the Pharmacia-ASPET Award for Experimental Therapeutics (2019), the Heinrich Wieland Prize (2020), the Scheele Prize (2021) and an honorary doctoral degree from the Technische Universität Dortmund, Germany (doctor rerum naturalium honoris causa) (2021).

Tim Shannon, MD


Over the past 30 years, Dr. Timothy Shannon has been an entrepreneur, executive, researcher, professor, and practicing physician. He is Executive Chair and member of the Board of Halda Therapeutics and a General Partner at Canaan Partners. He also serves or has served on the boards of several Canaan portfolio companies, including Arvinas, CytomX , IDEAYA Biosciences, NextCure, RallyBio, Normunity, Novira Therapeutics, Civitas Therapeutics, Vivace Therapeutics, and AER Therapeutics.

Previously, Dr. Shannon was President and Chief Executive Officer of CuraGen, a biopharmaceutical company focused on oncology, after serving as Executive Vice President of R&D and Chief Medical Officer. He also held positions of increasing responsibility for Bayer’s Pharmaceutical Business Group, including Senior Vice President of Global Medical Development. Prior to his career in industry, he was an Assistant Professor in the Pulmonary and Critical Care Division at Yale University School of Medicine.

Dr. Shannon received his B.A. in Chemistry from Amherst College, his medical degree from the University of Connecticut, and completed his postgraduate medical training at the Beth Israel Hospital of Harvard Medical School and Boston University.

Kat Kayser-Bricker, PhD


Dr. Kat Kayser-Bricker is an accomplished drug discovery leader with experience across several therapeutic areas and target families, with core expertise in small molecule cancer drug discovery. She joined Halda as an original team member shortly after founding, bringing her enthusiasm for company building, oncology, and platform innovation. She leads all scientific functions as well as strategic and operational aspects of the business. Previously, Dr. Kayser-Bricker spent 10 years as a key scientific leader at FORMA Therapeutics, a public company that was acquired in 2022 by Novo Nordisk for $1.1 billion. She held several roles with increasing responsibility, including Head of Early Discovery Chemistry where she was part of a three-person leadership team responsible for target nomination and validation, hit finding, and nomination for portfolio inclusion. She led numerous projects from hit finding through lead optimization and development candidate selection. She was responsible for maintaining several collaborative external alliances with academic and pharmaceutical partners for portfolio and technology advancements. She is a champion for innovation and led several technology initiatives including establishment of a DNA-encoded library platform. Dr. Kayser-Bricker was also part of the team that developed FORMA’s first drug candidate CC-95775 (FT-1101), a pan-BET bromodomain inhibitor that was exclusively licensed to Celgene in 2018.

Dr. Kayser-Bricker is passionate about diversity and inclusion and is a member of the Humanity Talent Network (HTN) Advisory Board and volunteer leader with Executive Women in Bio for the Connecticut Chapter. She performed her postdoctoral training in the lab of Scott Miller after receiving her Ph.D. in organic chemistry from Yale University in the laboratory of Andrew Hamilton. She received her bachelor’s degree in Biochemistry from the University of Maryland, College Park.

Scott Phillips


Scott Phillips has led finance organizations over the past 25 years from startup companies through large multinational commercial organizations. Scott is a founding member of the Halda executive team and has served as CFO for several venture-backed biotech companies, including Halda and Normunity, supporting these organizations from the earliest stages of their life cycle, including financing. Scott also served as SVP Finance for a public clinical stage development company leading the finance group in establishing operations as a public company.

Scott spent much of his biotech career at Alexion Pharmaceuticals where he served over 10 years in senior financial leadership roles as the company expanded from a pre-commercial business to a global commercial organization with over $4 billion in revenue. At Alexion, he led Global Business Finance, a finance organization comprised of strategic finance and financial planning and analysis, and also served as Chief Accounting Officer, in both cases leading global teams. Scott led finance diligence and integration teams for multiple acquisitions and was involved in over $5 billion of debt and equity financings, as well as complex projects encompassing all disciplines of finance.

Scott is a Certified Public Accountant who served as a Senior Manager in the technology practice of a Big 4 accounting firm, specializing in venture-backed companies, acquisitions and initial public offerings. He has a B.S. Business Administration and Masters of Accounting from the University of North Carolina at Chapel Hill.


Tim Shannon, MD General Partner, Canaan
Liam Ratcliffe, MD, PhD Managing Director, Access Biotechnology
Rebecca Velez Frey, PharmD President and CEO, Siduma Therapeutics
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