Throughout his career, Dr. Packer has been heavily involved in clinical and applied basic science research. His clinical research has touched on various aspects of adult and child neurology and neuro-oncology, including adult and pediatric brain tumors, neurofibromatosis type 1, the neurologic aspects of childhood neurogenetic diseases, and multiple other topics in general child neurology. Much of his research has focused on the development and performance of clinical trials for adults and children with neurologic, neuro-oncologic and neurogenetic disorders, and he has received peer-reviewed grant support for this research. Many of the clinical trials in neurofibromatosis and brain tumors are translational, bringing advances from the bench to the bedside expeditiously.

Presently, Dr. Packer is principal investigator (PI) at Children’s National for the Pediatric Brain Tumor Consortium (PBTC), formed under the auspices of the National Cancer Institute (NCI); chair of the PBTC Low-Grade Glioma Committee; site PI for Children's National for the Neurofibromatosis Clinical Trials Consortium; and chair of the Medulloblastoma Committee of the Children’s Oncology Group. He has worked closely with the NCI and the National Institute of Neurological Disorders and Stroke (NINDS), and has served on multiple committees setting the directions for neurologic clinical and basic science research for the future. He headed the efforts in pediatrics for the program review, held by the NCI and NINDS for brain tumors. He is presently co-chair of the Brain Malignancy Committee of the NCI. Much of Dr. Packer’s clinical research has been translational in nature. He has been part of studies evaluating the molecular genetics of childhood and adult neurologic diseases and also has coordinated the first gene therapy study for children with malignant brain tumors in the U.S. The majority of the studies now being coordinated by Dr. Packer are studies evaluating innovative agents aimed at the molecular underpinnings of neurologic disease. He has published over 400 original articles and 350 reviews and chapters.

In 2020 the International Symposium on Pediatric Neuro-Oncology bestowed its Lifetime Achievement Award on Dr. Packer for his substantial contributions to pediatric oncology and scientific achievements.