Using Mechanical Loading to Improve Cancer Treatments – Dr. Susannah Fritton

by Lylia Saurel

While cancer death rates decreased by 27% over the past 20 years, cancer remains the second leading cause of death in the United States, just after heart disease, as of 2020, according to the Centers for Disease Control and Prevention.

City College Department of Biomedical Engineering Professor Susannah Fritton is leading research efforts to examine how physical activity can be used to enhance drug delivery to bone tumors in order to improve the treatments of cancers that have spread to the bone.

Over the years, Fritton has studied how bone loss and gain work by focusing on the fluid surrounding the bone cells. In her current research, she looks at how mechanical loading — the technical term for physical activity — can help the fluid move into the bone’s pores to help pump drugs directly into bone tumors.

Alongside a group of CCNY students, she works with Dr. John Healey, a Memorial Sloan Kettering (MSK) orthopedic surgeon who specializes in treating sarcomas and noncancerous tumors of the bones and soft tissue.

Collaborating with other MSK scientists on a project funded by the CCNY-MSK Partnership’s National Institutes of Health U54 grant, their hope is that pumping drugs using mechanical loading can target metastasized tumors more directly than traditional IV chemotherapy. The conventional method has many adverse side effects due to the non-specific final destination of the drugs.

“If you get more drug going to where the cancer is, then you could reduce the overall drug dosage to the patients, thus reducing the undesirable side effects,” Fritton said. “It would improve the patients’ quality of life and make the treatment more effective.”

In order to get the most accurate results possible, Fritton and her team are using two distinct techniques: one that involves an animal model and one that uses a computational model.

For the animal component of the research, which is regulated by the Institutional Animal Care and Use Committee at MSK, cancer cells are injected into the tibia bone of rats to mimic the tumor of a human patient with breast cancer that metastasizes to bone. The rats are then placed on a treadmill to walk or on a vibrating plate that sends small vibrations through the skeleton, and drug delivery to the bone tumors is measured using in vivo positron emission tomography (PET) imaging. PET scans are used to produce detailed three-dimensional images of the inside of the body.

For the computational component of the research, the team makes models to analyze drug movement into bone tumors due to mechanical loading to complement the rat experiments and deepen their understanding of the processes at hand.
Fritton said that the research is still in development and at the experimental stage due to the important regulations around it, both in animal work and in the translation of the approach to humans.

“It’s a project that has taken a long time to develop and optimize the experimental techniques to assess whether the approach works,” she said. “We’re testing it in rats, but if it doesn’t work in rats, it will not likely be translatable to humans.”
The idea behind the mechanical load would be to have patients either slowly walk on a treadmill or stand on a vibrating device while receiving IV chemotherapy into their blood vessels.

Other factors will also play a role as to whether the approach will be successful or not, such as the ability of patients to stand up or walk without risking breaking their bones and the types of drugs being administered.

“If you can reduce the systemic dosage, you would improve the quality of life for these cancer patients, and it might improve their outcomes in terms of reducing the tumor burden in their bones,” Fritton said.

And if the research passes the developmental stage and achieves strong results, mechanical loading could be used to treat other conditions, including osteoporosis, which weakens bones to the point of breaking.

“Because people take drugs for conditions such as osteoporosis, we could maybe use these mechanical interventions to get the drugs into the bone for other diseases as well,” she said. “That would be the next thing we’re trying to do.”

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