“Cue dance party! Confetti! ‘Rocky’ theme song for my victory lap!” Caitlan Reese wrote on her blog in late September. Three years after being diagnosed with metastatic triple-negative breast cancer, Caitlan had been declared free of active disease and, much to her delight, she was able to stop the chemotherapy treatments that were causing nail infections and other side effects. After consulting with her oncologist, Dr. Antoinette Tan, chief of breast medical oncology at Atrium Health Levine Cancer Institute, Caitlan switched from an immunotherapy-chemotherapy regimen to immunotherapy alone.
Caitlan, 32, who lives in Hickory and has been blogging about her cancer journey, was clearly ecstatic that she could ditch the chemo and keep her cancer at bay with the immunotherapy drug Tecentriq (atezolizumab).
For Tan, determining the best course of treatment for patients with triple-negative breast cancer is a challenge, but also a labor of love. Triple-negative breast cancer accounts for an estimated 10% to 15% of breast cancer cases, according to the American Cancer Society. It is particularly aggressive and, because it lacks three key receptors – estrogen, progesterone and HER-2 – it doesn’t respond to treatments that hit those targets. Tan is enthusiastic about a wave of new treatment options that have been introduced in the last few years, including drugs like Tecentriq that stimulate the immune system to recognize and destroy cancer cells.
There is still a lot to be learned about the role of immunotherapy in treating triple-negative breast cancer, Tan says, but she feels confident there’s enough evidence to support treatment plans that don’t involve chemo for some patients, like Caitlan, who no longer have active tumors.
“Right now, I’m thinking about Caitlan’s quality of life,” Tan says. “She’s a schoolteacher. It’s hard to go back to teaching when you’re on chemo.”
“Very Exciting Times” for Patients
Tan has been at the forefront of treatment and research in triple-negative breast cancer throughout her eight-year career at Levine Cancer Institute. Just in the last few years, she has seen the standard of care for patients with metastatic disease shift from chemotherapy to more personalized treatment regimens. For example, patients whose metastatic tumors carry high levels of the protein PD-L1 can now be treated with a combination of chemotherapy and Keytruda (pembrolizumab), an immunotherapy drug that shrinks tumors by targeting PD-L1.
“Study results show the combination improves overall survival,” Tan says. “That has really changed the standard of care.”
Several targeted drugs are also offering new options to patients. They include medicines that inhibit a protein called PARP and, in doing so, kill cancer cells by preventing them from repairing their DNA. Tan is also enthusiastic about Trodelvy (sacituzumab govitecan), a drug that links two types of cancer-killing molecules, one of which targets TROP-2, a protein that’s found in most triple-negative breast tumors. In clinical trials, Trodelvy lowered the risk of death by 49% over chemotherapy and significantly improved survival.
“These are very exciting times for triple-negative breast cancer patients,” Tan says. “They now have access to drugs that are helping them live longer with their disease.”
Searching For New Treatment Targets
One of Tan’s passions is helping advance novel therapies for triple-negative breast cancer by serving as an investigator in clinical trials. She was a lead investigator in a phase 2 trial of Cosela (trilaciclib), a drug designed to protect the bone marrow from getting damaged by chemotherapy. The drug is currently approved to treat some lung cancer patients, and Tan hoped it would allow triple-negative breast cancer patients to stay on chemotherapy longer by preserving their red and white blood cell counts. She and the other investigators were surprised to discover that triple-negative breast cancer patients taking Cosela along with chemotherapy lived longer than those on chemotherapy alone, even though the drug did not significantly improve their blood counts.
“We’re still trying to sort out the mechanism – it may be immunologic – but seeing the gain in overall survival laid the foundation for a phase 3 study,” Tan says.
Tan is encouraged by a flood of research that continues to turn up new targets in triple-negative breast cancer. In 2023, she hopes to enroll triple-negative breast cancer patients in a phase 1 clinical trial of an investigational drug that’s designed to disrupt ADAM9, a protein on the surface of cancer cells that’s essential to tumor growth and spread.
One of Atrium Health’s own clinicians benefited from Tan’s leadership in clinical trials. Dr. Kristin Strawhun, an Atrium Health pulmonologist, was diagnosed with triple negative breast cancer in 2020. In addition to standard chemotherapy, she was enrolled in a clinical trial of an immunotherapy treatment. Strawhun’s cancer is now in remission, and she enjoys offering emotional support to patients with cancer who are dealing with side effects, such as hair loss from chemotherapy.
Strawhun is a big fan of Dr. Jaspal Singh, medical director of pulmonary innovation and oncology at Levine Cancer Institute, who recently led a turban-tying event for cancer patients.
“There aren’t enough words to say how great my Atrium Health Levine Cancer Institute team is,” Strawhun says. “My biggest hope for other people going through cancer treatment is that they know there are so many resources here to help them and their families.”
For Tan, helping researchers learn more about triple-negative breast cancer is one of the most important elements of her job at Levine Cancer Institute.
“It's fulfilling to be part of efforts to increase the treatment options for triple-negative breast cancer,” she says.
As for Caitlan, she was married in February, and Dr. Tan is optimistic that immunotherapy will help keep her cancer from progressing while also preserving a good quality of life. “She’s in a good place right now,” Dr. Tan says.
For patients with triple-negative breast cancer, she adds, “immunotherapy has been a game-changer.”
Learn more about breast cancer care at Levine Cancer Institute or call 704-302-9270 to make an appointment.
