The Oncology Institute of Hope and Innovation

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Hilda H. Agajanian, MBA


An extremely devoted and caring Administrator, Hilda Agajanian strives to ensure that all patient needs are met.  She is committed to providing optimal care for our patients during their most challenging times.  She has a Bachelor of Arts degree in Biology from the California State University, Northridge and a Master of Business Administration from the University of Phoenix.  Her range of experience derives from managing a spine center for numerous years to wealth management at UBS Financial Services.  Her diverse experience helps to cultivate a patient-centric culture and optimize patient satisfaction.

Mrs. Agajanian is fluent in  Armenian.  

Claudia Angeles

Authorizations Supervisor

Claudia is a very compassionate and dedicated person, who believes “every accomplishment begins with the decision to try!” Claudia has been in the healthcare industry since 1994 and is certified in Medical Billing/Claims Examiner from American Career College.  Since then, she has worked with various billing companies all specializing in Oncology/Hematology, in the Greater Los Angeles area. Over the past 15 years, her experience has included analyzing and reviewing analytical reports, with the goal to facilitate annual revenue resulting in profitable gain.  Cancer has also stricken Claudia’s family, and that is one of the reasons why she will do her best to help both the patients in need and the physicians who ultimately render services to all those patients in good faith.

Mrs. Angeles is fluent in Spanish.

Donna Arriaga

Director of Operations

Donna Arriaga comes to our organization with over 20 years of experience in the healthcare industry.  Mrs. Arriaga serves as Operations Manager for the practice. She oversees the day-to-day business activities for all office locations. She joins us with enthusiasm and compassion for our patients, their families and our staff members.  As Operations Manager, she ensures that all employees are highly qualified and well-trained professionals who are united and passionate in providing the highest standard of patient care. She is committed to making sure each patient is treated with compassion, respect and dignity.

Leeanne Fontes

Office Manager

Mrs. Fontes is a highly dedicated and compassionate manager who is currently working on a degree in business management.  She comes to our organization with 12 years experience in the healthcare field, 5 of those years in Oncology.  As an Office Manager, Leeanne strives to ensure that each patients' experience is personalized according to their needs. She is the liaison between the patients and the practitioners.  Her vast experience in Medical Oncology helps her provide optimal care for each and every one of our patients.

She not only contributes to the daily operations of our practice but provides empathetic and superior care for our patients.

Maria Garcia

Wellness Center Coordinator


Maria I. Garcia is the Wellness Center Coordinator at the Hope, Health & Healing Center in Whittier. She started her career in the medical field as a Medical Assistant, earning her certificate at the American Career College in 2006. Previously, Maria has been office manager at the Oncology Institiute. She has over 5 years of experience working in a variety of settings with an emphasis on Oncology. Maria uses her experience to help communicate and motivate patients the importance of the services at the wellness center. Her objective is to provide a warm and professional environment in which she can help patients foster balance in their lives. 

She is also bilingual and able to conduct business in English and Spanish.

Maria is married, has 3 girls and 2 boys. She enjoys spending her leisure time with family and friends. 

Mark Hueppelsheuser, Esq.

General Counsel & Compliance Officer

Mark Hueppelsheuser serves as the General Counsel and Compliance Officer of The Oncology Institute. Prior to studying law, Mr. Hueppelsheuser gained experience in the clinical sciences, specifically biology and psychology, and has been published in the Journal of Neurophysiology. Before joining The Oncology Institute Mr. Hueppelsheuser gained legal experience both in-house in the action-sport industry, as well as practicing civil litigation. After completing his Juris Doctor degree from Chapman University, Mr. Hueppelsheuser also completed his Master of Dispute Resolution from Pepperdine Law School’s Straus Institute. Over the past several years Mr. Hueppelsheuser has been involved extensively in mediating various hostile cases in both the Orange County and Riverside County courthouses.

Julie Miranda

Office Supervisor

Julie Miranda is a highly dedicated and compassionate Supervisor. She began her career in the field of healthcare over 20 years ago as a Unit Secretary in the Los Angeles area and has experience in many aspects of the healthcare industry.  Ever since her own mother’s passing of cancer, she has taken a more heartfelt interest for her work at The Oncology Institute. With her personal experience in dealing with cancer in her family, Julie knows how important it is to make our organization a loving and caring environment for all of our patients. She builds effective working relationships with fellow co-workers, patients, and their families and always makes herself available to all. Julie is a highly compassionate and understanding individual, who strives to make a difference in people’s lives, and for that, we are grateful to have someone like her at the Oncology Institute.

Kimthoa Pham

Billing and Collections Manager

Kimthoa Pham is a very compassionate and dedicated leader in our Insurance Billing Department.  She started her career in early 1990 and has worked with various facilities all specializing in Oncology and Hematology. Working side by side with Doctors, she has translated her experience beyond just billing and coding. Cancer had taken her mother away at a young age; she has made it her passion to make sure that insurers are paying for patients’ cancer care when they need it most. Her Insurance knowledge has helped patients to better understand the financial process and challenges that affect healthcare.  

She is fluent in Vietnamese.

Marni Rupp

Director of Human Resources

Marni Rupp is a highly caring and compassionate person. She began her career in the healthcare field as a Medical Assistant working with the USC Keck School of Medicine in the Division of Plastic and Reconstructive Surgery. While with USC, Marni not only worked as a Medical Assistant, she was also one of the Account Managers handling the coding and billing for the Division, and was subsequently promoted to an Office Manager in the Department of Internal Medicine. 

Marni is dedicated to the well-being of our patients and strives to ensure that patient needs are met during their most challenging times.

Barbara Trujillo

Office Manager

Barbara Trujillo is an energetic, compassionate, and a self-driven manager with over twenty five years of experience working with the public.  She changed her profession over thirteen years ago from working in the financial industry to healthcare because of her love for helping others. She is licensed and certified in medical assisting and as a phlebotomist.  She always strives to better herself, and is taking continuing education courses to extend her knowledge. She is competent in all aspects in the medical industry including back office procedures, authorizations, eligibility, scheduling, and collections. She uses her knowledge to build up her staff, and realizes that the most important thing for our patients is that we provide excellent service because they deserve nothing less.

Mila Voskanyan

Health Care Coach

Mila Voskanyan is extremely energetic, passionate, and dedicated Supervisor. She began her career in 2005 and has worked with various facilities in the medical industry. Mila received her Bachelor’s of Criminology and Psychology from University of La Verne, and her Masters of Organizational Leadership from Woodbury University.  She oversees the day-to-day activities for the Glendale office. 

Mila strives to make our organization a loving and caring environment for all of our patients and their families. She builds effective working relationships with her co-workers, patients, and their families and always makes herself available to all.

Mila is an exceptional individual, who strives to make a difference in people’s lives by always providing the highest level of patient care.

1184 N. Euclid St.
CA 92801

Tel. 714.399.0620
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900 S. Main St.
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Corona, CA 92882

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