Circle Pharma Strengthens Leadership Team to Advance Targeted Macrocycle Cancer Pipeline
Circle Pharma, Inc., a clinical-stage biopharmaceutical company focused on developing next-generation targeted macrocycle therapeutics for cancer, has announced two leadership appointments designed to support the company’s continued scientific development and organizational growth. Marie Evangelista, Ph.D., has been promoted to chief scientific officer, while Mary Ellen Sillivos has joined the company as senior vice president and head of human resources.
The appointments come as Circle Pharma advances its pipeline of targeted macrocycle therapeutics and builds the organizational capabilities needed for its next stage of development. The company is pursuing a drug discovery strategy centered on macrocycle-based medicines, with the goal of addressing cancer targets that have historically presented challenges for conventional small-molecule approaches.
According to Circle Pharma, the expanded leadership team will support the company as it continues to develop its proprietary MXMO™ platform and translate its scientific capabilities into potential new therapies for patients with cancer.
Marie Evangelista Promoted to Chief Scientific Officer
As part of the leadership changes, Circle Pharma has promoted Marie Evangelista, Ph.D., to chief scientific officer. In her expanded role, Evangelista will help guide the company’s research strategy and oversee scientific efforts as Circle advances its portfolio of targeted macrocycle therapeutics.
Evangelista has played an important role in the company’s research activities since joining Circle Pharma. Her promotion reflects the increasing importance of scientific leadership as the company progresses its discovery and development programs.
David J. Earp, J.D., Ph.D., president and chief executive officer of Circle Pharma, said Evangelista has been instrumental in shaping the company’s research strategy and advancing its pipeline. He added that her promotion recognizes the contribution she has already made and the role she is expected to play as Circle continues building its portfolio of novel macrocycle therapeutics.
In her statement, Evangelista highlighted Circle Pharma’s differentiated approach to macrocycle drug discovery. She noted that the company’s platform has the potential to address important cancer targets that have historically been difficult to reach using conventional small molecules.
As chief scientific officer, Evangelista will contribute to the continued development of Circle’s research programs and the broader application of the company’s MXMO™ platform. Her responsibilities will include helping guide scientific priorities as Circle works to identify and advance potential therapeutic candidates.
Macrocycles as a Drug Discovery Approach
Macrocycle therapeutics represent an area of drug discovery that has attracted growing interest because of their potential to interact with biological targets that may be difficult to address with traditional small-molecule medicines.
Conventional small-molecule drugs are often designed to bind specific pockets or sites within disease-related proteins. However, some biologically important targets have structural characteristics that make them challenging for traditional drug modalities. Macrocycles, which are larger and structurally more complex than many conventional small molecules, can provide additional molecular surfaces and binding characteristics.
Circle Pharma is developing its platform around this concept. Through its MXMO™ technology, the company aims to discover targeted macrocycle compounds capable of interacting with cancer-related proteins and pathways that may be difficult to modulate using established approaches.
The company’s strategy is focused on combining the drug-like characteristics of small molecules with the ability of macrocyclic compounds to engage challenging biological targets. The objective is to generate therapeutic candidates that can potentially expand the range of cancer targets accessible through orally or systemically delivered medicines, depending on the characteristics of individual programs.
For a clinical-stage biopharmaceutical company, advancing such a platform requires close coordination between discovery research, translational science, development planning and organizational execution. Circle’s latest leadership appointments are intended to strengthen those capabilities as the company moves forward.
Mary Ellen Sillivos Joins as Head of Human Resources
Circle Pharma has also appointed Mary Ellen Sillivos as senior vice president and head of human resources. In this position, Sillivos will support the company’s organizational development as it continues to grow its workforce and expand the capabilities required to advance its pipeline.
Sillivos brings experience in building and supporting organizations at different stages of growth. Her appointment is intended to help Circle Pharma develop the people, culture and organizational infrastructure necessary to support its scientific and business objectives.
Earp said Sillivos’ experience will be valuable as Circle continues to evolve and expand the capabilities required to execute its plans. He emphasized that strengthening the company’s leadership team is important as Circle enters its next stage of development.
Sillivos said she was pleased to join Circle Pharma at an important point in the company’s evolution. She plans to work with Earp and the broader leadership team to build the organization, culture and capabilities needed to support continued growth and pipeline advancement.
Her role will extend beyond traditional human resources functions as Circle continues to develop as a clinical-stage biotechnology company. Building an organization capable of supporting advanced research and development programs typically involves establishing appropriate talent strategies, leadership structures, employee development programs and organizational processes.
For Circle, these capabilities will become increasingly important as the company progresses its pipeline and potentially expands its scientific and operational activities.
Leadership Expansion Supports Next Stage of Growth
The two appointments address complementary aspects of Circle Pharma’s development. Evangelista’s promotion strengthens the company’s scientific leadership at a time when Circle is focused on advancing its macrocycle discovery platform and therapeutic pipeline. Sillivos’ appointment strengthens the organizational side of the business by adding leadership focused on talent, culture and human resources.
Together, the appointments reflect Circle’s efforts to build the infrastructure required to support the company’s transition through different stages of growth.
For emerging biopharmaceutical companies, leadership requirements often evolve as research programs move toward clinical development. Scientific organizations may need to expand their discovery, translational and development capabilities, while companies also need to establish the organizational structures necessary to support a growing workforce.
Circle Pharma’s latest leadership changes are aligned with those requirements. The company is seeking to maintain momentum in its scientific programs while developing the internal capabilities needed to support continued expansion.
Advancing the MXMO™ Platform
At the center of Circle Pharma’s research strategy is its MXMO™ platform, which the company is using to discover targeted macrocycle therapeutics. The platform is intended to support the development of compounds against cancer targets that may not be readily addressable through conventional small-molecule drug discovery.
Evangelista’s expanded responsibilities are expected to be particularly relevant as Circle continues to apply the platform across its research portfolio. Her focus will include translating the company’s discovery capabilities into potential therapeutic programs and supporting the scientific strategy that guides the pipeline.
The company’s approach reflects a broader effort within the biopharmaceutical industry to develop new modalities capable of addressing previously challenging targets. Advances in drug discovery technologies have enabled researchers to explore a wider range of molecular structures and mechanisms, potentially creating opportunities for therapeutic intervention in areas that have historically been difficult to target.
Circle Pharma is positioning its macrocycle platform within this evolving landscape, with an emphasis on cancer biology and targeted therapeutics.
Building an Organization Around Innovation
While scientific innovation remains central to Circle Pharma’s strategy, the company’s leadership recognizes that successful drug development also depends on organizational execution. The appointment of Sillivos as head of human resources highlights the importance of building an organization capable of supporting the company’s scientific ambitions.
As Circle grows, attracting and retaining employees with expertise in drug discovery, cancer biology, medicinal chemistry, clinical development and other areas will be important to maintaining progress across its programs. Establishing a strong organizational culture can also help coordinate teams working across different stages of therapeutic development.
Sillivos will work alongside Circle’s executive leadership to help establish those capabilities. Her experience with organizations at multiple stages of growth is expected to support Circle as it develops its workforce and prepares for future expansion.
The company’s leadership structure will therefore combine strengthened scientific direction with increased organizational support. This combination is intended to position Circle to continue developing its technology platform while preparing for the operational demands associated with a growing clinical-stage biotechnology company.
Circle Pharma’s promotion of Marie Evangelista to chief scientific officer and appointment of Mary Ellen Sillivos as senior vice president and head of human resources represent important additions to the company’s leadership structure.
Evangelista will take on an expanded scientific leadership role as Circle continues to advance its MXMO™ platform and pipeline of targeted macrocycle therapeutics. Her experience within the company and involvement in shaping its research strategy provide continuity as Circle develops its next generation of cancer-focused programs.
Sillivos, meanwhile, will focus on strengthening the organizational foundation supporting Circle’s growth. Her responsibilities will include helping develop the culture, talent strategy and capabilities needed to support the company as it progresses its pipeline.
With these leadership changes, Circle Pharma is continuing to align its scientific and organizational resources with its development objectives. The company remains focused on using its macrocycle drug discovery approach to explore new opportunities in cancer therapeutics and to develop potential treatments for patients with significant unmet medical needs.
As Circle advances its research programs, the company’s strengthened leadership team will play a central role in determining how its technology platform and pipeline develop in the coming stages. The appointments of Evangelista and Sillivos provide additional leadership across both scientific strategy and organizational development as Circle Pharma works toward its longer-term goal of translating its macrocycle drug discovery capabilities into new cancer therapies.
About Marie Evangelista, Ph.D., chief scientific officer
Dr. Evangelista joined Circle in 2024 as senior vice president and head of cancer biology. Previously, she held the position of vice president of oncology at Recursion, leading the oncology group and advancing their internal pipeline while establishing key partnerships with Genentech/Roche and Bayer. Before that, she spent 18 years at Genentech, directing precision oncology programs focused on cell cycle, tumor metabolism, and targeted therapy resistance.
She played a crucial role in developing GDC-6036 (Divarasib), now in Phase 3 trials. Dr. Evangelista earned her Ph.D. from Queen’s University in Canada, receiving the NSERC Doctoral Prize and the Governor General’s Gold Medal. She completed postdoctoral training at Genentech with Fred de Sauvage. Dr. Evangelista has published over 40 papers in top journals, including Science, Cell, and Nature Biotechnology, and holds a dozen patents.
About Mary Ellen Sillivos, senior vice president and head of human resources
Mary Ellen Sillivos brings over thirty years of experience in the biotech and biopharmaceutical industry. Prior to joining Circle, Ms. Sillivos held several leadership positions including serving as vice president, human resources at Quince Therapeutics and Cortexyme.
Previously, she held positions of increasing responsibility, including vice president, human resources at Dermira and executive director, human resources at Affymax. She has broad experience in all aspects of HR operations, specifically within early stage and start-up companies through commercialization. Ms. Sillivos attended the University of San Francisco and is a certified Senior Professional in Human Resources (SPHR).
About Circle Pharma
Circle Pharma is a clinical-stage biopharmaceutical company harnessing the power of macrocycles to develop next-generation targeted therapies for cancer and other serious illnesses. Circle Pharma’s proprietary MXMO™ platform overcomes key challenges in macrocycle drug development, enabling the creation of intrinsically cell-permeable and orally bioavailable therapies, including for historically undruggable targets. Circle Pharma’s pipeline is focused on targeting cyclins, key regulators of the cell cycle that drive many cancers. Circle Pharma is based in South San Francisco, CA.