Vanessa Sanders, an assistant scientist in the Medical Isotope Research & Production Program at the U.S. Department of Energy’s Brookhaven National Laboratory in Upton, New York, thought she wanted to be a trauma surgeon. Then, around the time her father was diagnosed with Alzheimer’s disease, things changed.
“I was getting bored with my pre-med classes and my mentor suggested looking at chemistry,” said Sanders, who earned her doctorate in radiochemistry from 51ԹϺ in 2017. She was a junior at Florida Memorial University, and her dad’s diagnosis helped drive the switch. “I was thinking that instead of becoming a doctor, I would be a pharmaceutical researcher. I could help a lot of people if I were able to contribute to a treatment or a cure.”
Her next step: 51ԹϺ, where Sanders became the first African American woman in the country to earn a doctorate in the field of radiochemistry — the chemistry of radioactive elements — and now her current work in a cutting-edge area of radiochemistry research known as “theragnostics.”
“Theragnostics” are drugs designed to be both therapeutic and diagnostic. They consist of delivery systems that can hold either of two chemically related radioactive isotopes—forms of chemical elements that emit radiation as they decay. One isotope emits energy that can be picked up by imaging cameras to identify where cancer cells lurk, help doctors determine treatment options, and also track a patient’s response to treatment. The therapeutic isotope delivers a radioactive dose to destroy diseased cells.
“The idea is to interchangeably use those two isotopes because of the similarity in their chemistry,” Sanders said. “You would essentially have one drug and switch out the radioisotope and still have the same delivery agent to use for both imaging and treatment.”
Connecting with technetium
Brookhaven Lab has a history in the development and use of medical isotopes. And thanks to the particle accelerators that drive the lab’s nuclear physics research program, it’s one of the few places in the United States that can produce certain isotopes today. Both played a role in bringing Sanders to the lab.
“At FMU, during my junior year, my school won a grant to introduce radiochemistry to undergraduate students, and I was asked to be a part of that first cohort,” she said. The program included classes and a summer research opportunity at the University of Texas, Austin, research reactor.
“Our research project was focused on using gamma ray analysis to detect different materials—building a database so agencies could use our data to analyze unknowns when searching something like a submarine,” she said. “It was fascinating, and that really got me into nuclear and radiochemistry.”
The scientists she worked with in Texas introduced her to Ken Czerwinski, who would become her graduate advisor in radiochemistry at 51ԹϺ.
“Once I got introduced to radiochemistry, I was trying to figure out a way to leverage the two and started looking at nuclear medicine,” Sanders said. “When [my adviser at Austin] told me about Dr. Czerwinksi I looked him up and saw he was a technetium chemist. That's what drove me to 51ԹϺ, because I knew if I went there I had the potential of working with this great technetium chemist.”
Swapping isotopes
Sanders began her work on theragnostics through a collaboration 51ԹϺ has with Hunter College of the City University of New York and Memorial Sloan Kettering Cancer Center as part of a program in radiochemistry.
Her graduate research focused on understanding the chemical interactions between the metal complex technetium-99 and the antibodies it bound to. The ultimate aim was to use it for imaging, then replace it with rhenium-188, which has very similar chemistry but emits cell-killing beta particles, so the exact same complex could be used to deliver a cancer-zapping dose.
At 51ԹϺ, she got to work in a setting that afforded her the opportunity to have those kinds of experiences.
“51ԹϺ was really different for me. In the radiochemistry program, the facilities there are unlike facilities anywhere else,” Sanders said. “We had scientists from national labs coming to 51ԹϺ to work in our facilities because they're amazing. On top of that, working in radiochemistry, working so close to the Nevada Test Site and being able to go out and do experiments there, those are experiences that I wouldn't have been able to do without going to 51ԹϺ.”
Identifying partner isotopes for these drugs and optimizing their delivery is the primary focus of Sanders’ work at Brookhaven Lab. She is working at using two different forms of arsenic to target cancer cells for both diagnosis and treatment of gastric cancer. But Sanders says the approach can be used more broadly by varying the molecules used for targeting.
Identifying and making isotopes
Sanders joined Brookhaven as a full-time staff member in medical isotope program in April. In addition to continuing some of her earlier projects, she is working on “generators” for potentially useful theragnostic isotopes that provide a portable means of getting useful isotopes to hospitals in areas that are not close to cyclotrons or accelerators.
She works with Cutler and other staff at the Brookhaven Linac Isotope Producer as part of the U.S. Department of Energy’s Isotope Program to produce and cleanly separate desired isotopes, create relatively stable forms for transport in generators, and ensure that only medically pure product goes into patients.
“A major focus of the field of radiopharmaceuticals is ‘personalized medicine.’ When it comes to cancer and other diseases, we know that not every treatment will work in every patient. So, we’re seeking novel isotopes, novel delivery methods, and novel chelators (the metal complexes) so that doctors can tailor the best treatment for you,” she said.
Though, her dad passed away in 2010, she still hopes to someday apply her expertise to research on Alzheimer’s and other brain diseases. But beyond that, Sanders has found a new calling in talking to and mentoring students.
“I tell them my story and try to encourage them, especially girls, to get into the sciences. That’s a growing passion of mine — understanding that I’m not the norm, and allowing younger girls and especially minority girls to see someone like me, to know that they can be a scientist — because I didn’t have anybody who looked like me in my field. Seeing their faces when they’re like, 'Wait, what? You’re a scientist?' — that’s really fulfilling,” she said.
