MEET OUR TEAM
Conveniently located to serve the areas of Los Angeles, Woodland Hills, Agoura Hills, Northridge, Van Nuys, Sherman Oaks, Thousand Oaks, Tarzana, Encino, Chatsworth, Calabasas, Bell Canyon and Westlake Village.
Cinical Team
Administrative Team
MBSR
Virtual Assistants
Nazanin Firooz, MD, FACR
Dr. Firooz is board-certified in Rheumatology and Internal Medicine. She is an active member of the American College of Rheumatology, and is affiliated with the Department of Rheumatology at Cedars Sinai Medical Center. She received her medical degree from the University of California at Irvine, and completed her residency at University of California, Los Angeles (UCLA) and Los Angeles Veteran’s Hospital. She trained at Cedars Sinai Medical Center for her fellowship in rheumatology.
Dr. Firooz has been published in peer-viewed medical journals and has presented her research in several national rheumatology meetings. She is the recipient of a research award for her presentation at the American college of rheumatology in Washington, D.C.
Realizing the rapidly evolving nature of the field of rheumatology, with new discoveries and treatments that can improve the lives of many patients, Dr. Firooz keeps her commitment to her patients up-to-date by attending the Carl Pearson rheumatology update meeting at UCLA and the American College of Rheumatology scientific meeting every year. She reviews the latest discoveries in the field with several other rheumatologist at the monthly journal club meetings at Cedars Sinai. She prides herself at offering her patients the latest in diagnostic approach and available treatments.
In her free time, Dr. Firooz enjoys traveling, oil painting and salsa dancing. She is fluent in English, Farsi, and Medical Spanish.
Phillip Aleksiejuk, MD
Dr. Aleksiejuk is a board certified physician in both Rheumatology and Internal Medicine. He completed Rheumatology fellowship training at the University of Southern California (USC).
Originally from Toronto, Canada, he realized at a young age that he wanted to pursue a career in medicine after spending countless hours filing medical records at his father’s medical practice. He trained at SUNY Upstate Medical University where he found his passion for diagnosing and treating autoimmune disease.
Dr Aleksiejuk understands the value of comprehensive medical care especially in Rheumatology, given the chronicity and multi-systemic nature of the conditions. He finds immense joy in establishing long-term relationships with his patients and works relentlessly to improve their quality of life. With all of the exciting developments in the field, he strives to formulate individual treatment plans while maintaining a holistic approach.
Outside of medicine, Dr. Aleksiejuk loves to spend time with his family, travel and follow everything related to sports.
Rana Taherian, MD
Dr. Rana Taherian is a double board-certified rheumatologist (ABIM)
dedicated to high-quality, patient-centered care for autoimmune and
inflammatory diseases.
She specializes in diagnosing and managing osteoporosis, rheumatoid
arthritis, lupus, scleroderma, vasculitis, spondyloarthropathies, and
other rheumatic conditions. With expertise in joint injections,
musculoskeletal ultrasound, and advanced DMARD therapies, she focuses
on personalized treatment and multidisciplinary care.
Fluent in English and Farsi, she is committed to
clear communication and strong patient relationships.
Outside of medicine, she enjoys playing piano, beach outings and water
activities, and spending quality time with family and friends.
Sabrina Roofian - PA-C
Meet Sabrina, a dedicated Physician Assistant (PA-C) with a strong academic foundation and a passion for patient-centered care. She earned her undergraduate degree from UC Santa Barbara before going on to complete her Master’s training at Loma Linda University.
Sabrina brings a dynamic and well-rounded clinical background, with experience in both urgent care and rheumatology. This unique combination allows her to approach complex autoimmune and musculoskeletal conditions with both precision and a broad perspective, ensuring patients receive thoughtful, comprehensive care.
Known for her approachable demeanor and attention to detail, Sabrina is committed to helping patients better understand their conditions and feel confident in their treatment plans. Whether managing chronic rheumatologic diseases or addressing acute concerns, she strives to create a supportive and collaborative healthcare experience for every patient she serves.
Kamari Calloway
Kamari is our Office Administrator. She offers support and troubleshooting to our staff, office, and patients. She coordinates seamless operations of the office, while maintaining policies and procedures. With an interest in healthcare administration and informatics, she strives to utilize her growing experience and skills to further her career in the medical field. In her free time, she enjoys going to restaurants, spending time with family and friends, and traveling.
Tannia Villalobos
Tannia began her journey with our practice in 2014 as a student and has since grown into an essential, dedicated member of the organization. Over the past decade, she has advanced into the role of Biologics and Infusion Coordinator, overseeing the infusion and injectable department — managing specialty medication care, insurance authorizations, coordination with specialty pharmacies, and ensuring timely delivery and administration of therapies.
She remains deeply committed to supporting patients through every step of the process, whether navigating prior authorizations, securing copay assistance, or connecting patients with free drug programs. A certified phlebotomist and IV technician, she brings both clinical skill and precision to the in-house infusion center, while also playing an active role in supporting and growing the practice’s in-house pharmacy to streamline access to specialty medications.
Outside of work, Tannia enjoys cooking, arts and crafts, and spending time with her family. A proud mother of two, she values the balance between her professional growth and her family life. After more than 10 years with the practice, she continues to view the team as a second family and takes great pride in contributing to its growth, evolution, and success.
Suman Rizvi
As the Operations Administrative Coordinator, Suman helps oversee administrative processes, supports office operations, and works to improve systems that enhance both the patient and staff experience. She earned her Bachelor of Arts degree in Communication with a minor in Public Relations from Chapman University, bringing strong organizational and interpersonal skills to everything she does.
She enjoys finding ways to streamline workflows, improve efficiency, and support the team behind the scenes to help the practice run smoothly. Outside of work, she enjoys staying active through fitness, Brazilian Jiu-Jitsu, and dancing, as well as spending time with family and friends.
Jamie Leongzon
As a medical assistant, Jamie is responsible for taking patient vitals, asking medical history questions to make sure our patient charts are up to date, and giving injections. If she is not helping out in the back, you can find her in the front answering phones and helping in the check-in and check out process. She has always had a passion for the medical field and hopes to one day use the tools she’s learned here to further her skills in her future career. Outside of work she enjoys singing, traveling, or dancing.
Millie Perez
Millie is a Medical Assistant who is passionate about helping others and making patients feel supported and cared for. Working closely with patients has reinforced her desire to pursue a career as a registered nurse, where she hopes to continue providing compassionate care and making a positive difference in the lives of others. In her free time, she enjoys watching movies, attending music festivals, and spending quality time with her friends and family.
America Jimenez
America is a medical assistant who is passionate about listening to each patients’ individual needs and circumstances. She assists with rooming patients, taking vital signs, administering injections, and supporting the front office by answering phone calls and scheduling. She earned her Bachelor’s degree in Biopsychology from University of California, Santa Barbara and is currently in the process of applying to medical school. America is passionate about helping patients overcome barriers that stand between them and care. Outside of work , America enjoys soccer, going to the beach, listening to music, and fashion.
Alejandra Contreras
Alejandra is a dedicated Medical Assistant who enjoys helping patients feel comfortable and cared for throughout their visit. She assists with rooming patients, taking vital signs, administering injections, and supporting the front office by answering phone calls and helping patients schedule appointments.
She earned her Bachelor’s degree in Biology from California State University, Northridge, and is currently pursuing a Master’s degree to become a Physician Associate. Alejandra is passionate about healthcare and values the opportunity to build meaningful connections with her patients while making a positive impact on their lives.
Outside of work and school, Alejandra enjoys spending time at the beach, exploring local hiking trails, and making memories with friends and family.
Sharzad Firooz
Sharzad has a certificate in Mindfulness Based Stress Reduction (MBSR), a bachelors in human development, and a masters in psychology, and is a certified Mindfulness Meditation teacher. As the MBSR coordinator at our site, she can answer questions about the MBSR program and can help you learn how to better manage pain and other chronic symptoms.
Sharzad is also a mother of two, a former school psychologist, and teaches bilingual preschoolers through music and dance on her off days. She is an alumni of UC San Diego, and Cal State Northridge.
She loves yoga, singing, learning about mindfulness, reading, and finding many variations of the same song. Figure skating and basketball are her favorite sports to watch, though she is not great at either. Sharzad also enjoys a variety of TV and movie fandoms, including Avengers, Star Wars, Lost, Hamilton, Buffy The Vampire Slayer, and especially Harry Potter. Did we mention she is a Harry Potter fan?!
Alyssa Villamor
Alyssa is a dedicated medical biller who takes pride in her work and enjoys helping patients navigate all their billing and insurance concerns. She is committed to ensuring that claims are processed accurately and efficiently while providing patients with the support and assistance they need. Outside of work, Alyssa enjoys reading books, listening to music, singing, watching movies, attending concerts, and going to the gym.
Christine Riveta
Flexie Ancero
Flexie is passionate about helping patients access the medications they need. She supports patients by submitting prior authorizations, securing copay assistance, and connecting them with free drug programs when available. She also works closely with the in-house pharmacy to streamline access to specialty medications, helping patients receive their treatments more easily and with fewer delays.
Outside of work, Flexie enjoys spending quality time with her family through staycations, traveling, surfing, biking, going to events and gigs with friends, dancing, swimming, or simply enjoying a good meal together. She is a proud mother of one and a loving pet mom to three Chihuahuas, one cat, and, of course, some fish!
Flexie believes that helping patients navigate the process of accessing their medications is more than just part of her job—it’s a meaningful way to make a difference in their healthcare journey. She hopes to be remembered not just for the help she provides, but for the genuine care, kindness, and dedication she brings to every patient she works with.
Jedd Nielo
Jedd’s mission is to make every step of the patient’s treatment journey as smooth, clear, and accessible as possible. He strives to provide accurate insurance and benefits information, help patients understand their financial responsibilities, coordinate timely medication deliveries, and connect eligible patients with available financial assistance programs.
By maintaining accurate infusion and injection records and supporting the nursing team with organized and reliable information, Jedd contributes to efficient patient care. His goal is to make a meaningful difference by helping patients receive the treatment they need while making the process easier and less overwhelming for them.
Outside of work, Jedd enjoys spending time outdoors, especially riding his bike and discovering scenic routes. He and his family make it a point to plan trips at least once a month to explore new places, enjoy quality time together, and create memorable experiences.
Jowell Oliveros
Jowell Oliveros is a Medical Virtual Assistant who provides administrative and clinical support to the healthcare team. His responsibilities include submitting referrals and authorizations, processing medication authorizations, ensuring the necessary medical records are available before patient appointments, scheduling patients, making outbound calls to insurance companies and third-party groups, and uploading documents to patient accounts. He is committed to providing accurate, efficient, and dependable support to help ensure smooth office operations and quality patient care.
Jowell takes pride in being dedicated, reliable, and committed to supporting the healthcare team and patients. Outside of work, he enjoys traveling, going on motorcycle rides, watching movies, and reading books.
Kathrine Locsin
I track aging accounts and contact insurance payers regarding delayed or unpaid claims. I also research rejected or denied claims, correct billing or coding errors, and file formal appeals with supporting documentation.
Outside of work, I spend time with family and friends. I also love to travel and go to the beach.
Lianne Villamor
As a New Patient Coordinator, I’m dedicated to making each patient’s experience as smooth and welcoming as possible. I assist new patients with scheduling consultations, gathering the necessary information, and helping ensure they feel prepared and supported throughout the process. I also help our front office team with follow-up and medication appointments.
I enjoy building meaningful connections with patients and being part of a team that makes a difference in their healthcare experience.
Outside of work, I enjoy expressing my creativity through singing, crocheting, cooking, watching movies, attending concerts, traveling, and staying active at the gym. I especially love spending quality time with my friends and family.
Marie Gascon
Marie is a Virtual Medical Assistant supporting the healthcare team by handling insurance verification, referrals, and prior authorizations for patients. As a Registered Nurse in the Philippines, her healthcare background and commitment to quality patient care to provide efficient and reliable support to both patients and healthcare providers.
Outside work, she enjoys listening to music, spending time at the beach, learning how to do surfing and traveling with her family.
Zach Calderon
Zach is a dedicated Biller specializing in payment posting, with a keen eye for detail and a strong affinity for numbers. He takes pride in ensuring that insurance payments from various insurance companies are posted accurately and efficiently. He also carefully reviews and flags denied claims while ensuring that patient balances are accurate and up to date. His thoroughness, accuracy, and attention to detail help keep the payment posting process organized and running smoothly.
Outside of work, Zach enjoys going to the gym, watching movies, creating content, listening to podcasts, and spending quality time with his family.