Dr. Margaret Callahan: ‘We Can Offer Patients Hope’

reprinted from Issue 24, Spring 2017 of Frontiers of Medicine (PDF)

Margaret Callahan, MD

UCSF resident alumna Margaret Callahan, MD, PhD, leads clinical trials of new immunotherapy drugs at Memorial Sloan Kettering Cancer Center in New York.

When UCSF resident alumna Margaret Callahan, MD, PhD, began her medical oncology fellowship in 2009, treatment options for patients with metastatic melanoma were dismal. Only a tiny fraction of patients responded to therapies, and most died within months.

That landscape changed dramatically with the emergence of cancer immunotherapy – which has been particularly effective in melanoma patients, for reasons that are not yet understood.

“The conversations we have with patients today are very different,” said Callahan, now an assistant attending in the Melanoma and Immunotherapeutics Service at Memorial Sloan Kettering Cancer Center in New York, where she completed her fellowship. “Today we have some really good options, and it’s very likely we’ll find a therapy that works for you. We can offer patients hope, and we have the drugs and the data to back it up. Many patients I treated during my fellowship are cancer-free or cancer-controlled – four, five, six years later.”

Callahan first learned about cancer immunotherapy in the early 2000s, when she was just starting her joint MD-PhD program at the University of Connecticut. “I was all set to go into genetics, but I heard a talk on immunotherapy and thought, ‘This is so cool!’” she said. “There were a lot of people who didn’t think it was such a great idea, but I saw that if we could understand the immune system better, we could mold it into a tool to fight cancer.”

Asking the Next Question

She earned her PhD in immunology along with her medical degree, then chose UCSF for her internal medicine residency. “My experience at UCSF was really foundational, and the skill sets I got there are imprinted on me,” said Callahan. “The program did a very good job of teaching residents to ask the next question. If something about a diagnosis doesn’t fit, we learned to ask what else could possibly explain it. That’s served me well in so many different avenues.”

She also appreciated career guidance from Harry Hollander, MD, director of the residency program. Because she planned to complete a research-oriented fellowship, Callahan “fast-tracked” through residency – compressing her clinical training into two years rather than the usual three, and adding an extra research year to her fellowship. That required her to apply for fellowships just three months into her internship year.

“Dr. Hollander sat down with me early on, and made sure I was reflecting on decisions for my career pathway,” said Callahan. “He also helped me get all my paperwork in, and enabled me to have time to interview on the East Coast during my intern year, when I didn’t have a lot of control over my schedule. Those things aren’t small at all.”

“Maggie had all the intellectual energy one finds in top physician-scientists, coupled with the compassion and kindness that convinced me that she would be a terrific clinical oncologist,” said Hollander. “In a very short time, she has made major contributions to the immunotherapy revolution that has swept over oncology.”

As a faculty member at Memorial Sloan Kettering, Callahan leads clinical trials of new immunotherapy drugs and combinations, and actively pursues many research questions. “I’d like to know why immunotherapy works for one patient but not another, and what we can do to improve activity and make side effects easier to tolerate,” said Callahan. “How can we improve our understanding of our patients’ immune systems so we can better deliver therapies that work? No one therapy will be the magic cure for all cancers, but there is lots of room to improve what immunotherapy can deliver.”

Callahan is married to Joseph Grosso, PhD, a cancer researcher. Together they have a young daughter, Olivia.

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