Johns Hopkins All Children's Hospital

Meet Our Team

The Neuro-Oncology Program utilizes a multidisciplinary team approach to infants, children, adolescents, and young adults with brain and spinal cord tumors.

Stacie Stapleton, MD Hematology / Oncology

Dr. Stapleton is the division chief of oncology and director of pediatric neuro-oncology at Johns Hopkins All Children’s Hospital. Dr. Stapleton joined the hospital in 2007 and is double-board certified by the American Board of Pediatrics in general pediatrics and pediatric hematology/oncology. She has formal training in pediatric neuro-oncology. Dr. Stapleton is on the Pediatric Palliative Care Team at Johns Hopkins All Children’s and she specializes in symptom control and end of life care. She has been awarded numerous grants for phase I studies for patients with brain and spinal cord tumors as well as clinical research in pediatric palliative care. Dr. Stapleton’s research experience includes investigator-initiated and multi-center research projects.
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Thomas Geller, MD Neurology

Dr. Geller specializes in pediatric neurology for the Johns Hopkins All Children’s Institute for Brain Protection Sciences. He sees patients at the main campus in St. Petersburg and at Johns Hopkins All Children’s Outpatient Care, North Port. He joined the hospital staff in 2018. Dr. Geller previously was a pediatric neurologist and child neurology residency program director at Cardinal Glennon Children's Medical Center in St. Louis, Missouri. He retired as a captain from the U.S. Navy Medical Corps. His clinical and research interests include neurofibromatosis, neuro-oncology and pain management.
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Valerie Cruz Flores, MD Hematology / Oncology

Dr. Cruz Flores is a pediatric oncologist at Johns Hopkins All Children’s. She joined the hospital staff in 2020. She earned her medical degree from the University of Puerto Rico School of Medicine. She completed an internship and residency in pediatrics at the University of Puerto Rico School of Medicine, where she also served as chief resident. She completed a fellowship in pediatric hematology-oncology at Louisiana State University Health Sciences Center/Children’s Hospital New Orleans, followed by a fellowship in pediatric neuro-oncology at Johns Hopkins All Children’s.
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Claudia  Lukas, PA-C

Claudia Lukas, PA-C

Claudia Lukas is a certified physician assistant who joined the Johns Hopkins All Children’s Hospital neuro-oncology team in May 2017 and has worked as an advanced practice provider with the hematology-oncology division at Johns Hopkins All Children’s since 2003. She earned her Master of Science in Physician Assistant Studies at Northeastern University in Boston. She is a member of the Florida Academy of Physician Assistants, the American Academy of Physician Assistants, the Children’s Oncology Group and the Society for Neuro-Oncology. As co-investigator on multiple Children’s Oncology Group, institutional and industry-run clinical trials, she plays an integral role in the conduct of research at John’s Hopkins All Children’s.


Sonja Steinbrueck, R.N.

Sonja Steinbrueck, R.N.

Sonja Steinbrueck is the neuro-oncology nurse at Johns Hopkins All Children’s Hospital. She joined the hospital in pediatric hematology/oncology in 1996. She has been working specifically in neuro-oncology since 2007 and coordinates both the neuro-oncology and the neurocutaneous disorders clinics. She provides direct patient care, case management and participates in research. She received a bachelors in biology from Florida State University and a bachelors in nursing from the University of South Florida. She is certified in chemotherapy by the Association of Pediatric Hematology/Oncology Nurses (APHON) and is a recipient of the Daisy Award and the Good Catch Award.