Her life changed dramatically in 2015 when she was diagnosed with stage 3 breast cancer. When the cancer returned in 2024 as stage 4, she feared she had only months left. Instead, thanks to advances in treatment, Jackson is still thriving. She credits her current therapy, Kisqali (Ribociclib), which she calls her “magic pill”—for helping control her disease by interrupting cancer cell growth.

Kisqali is a CD4/CD6 inhibitor, a class of medications that can be used to treat certain types of hormone receptor-positive breast cancer. It’s currently approved for estrogen receptor-positive (HR+), HER2- negative metastatic breast cancer subtypes, and has become a game‑changer for many patients.

Estrogen receptor-positive means a breast cancer needs the hormone estrogen to grow.

Other CDK4/6 inhibitors on the market include Ibrance and Verzenio, all taken orally.

“CD4/CD6 inhibitors are working with estrogen receptor blockers like aromatase inhibitors to decrease the amount of estrogen that can be taken up into a cancer cell and decrease the growth rate at which a cancer cell can grow and expand,” said Dr. Elizabeth Comen, medical oncologist at Memorial Sloan Kettering Cancer Center.

WATCH: CDK4/6 Inhibitors for Breast Cancer, Explained

She adds, “For women with metastatic, estrogen receptor‑positive, HER‑2 negative breast cancer, CD4/CD6 inhibitors can improve what we call progression‑free survival”—the length of time patients live before the cancer grows again.

Jackson’s experience has inspired her to write a book, “Not Dead Yet,” chronicling her diagnosis, recurrence, and how cancer reshaped her understanding of mortality.

When describing the recurrence, Jackson said doctors told her it was inoperable, explaining they “cannot operate and cut out the marble in my chest that is laying on my windpipe, and eventually would suffocate me to death.”

“I’m not good in science or math, but I expected it could come back. I kind of forgot about it for nine years. I forgot I had cancer,” she shared on Instagram.

WATCH: What are the Treatment Options for Late‑Stage Breast Cancer?

For metastatic breast cancer, treatment focuses on controlling spread. SurvivorNet provides information on available options—from targeted therapies to chemotherapy—and when each may be used. We also highlight emerging research in clinical trials and explain when newly approved treatments, including immunotherapies, may be appropriate.

To explore clinical trials that may be a fit for you or a loved one, try SurvivorNet’s Clinical Trial Finder.

Managing Metastatic Breast Cancer

Late-stage breast cancer is not one disease, but many different diseases, so the options available to different patients vary a great deal. Which treatment doctors recommend will depend on several factors like a woman’s overall health, genetics, the biology of the tumor, and more.

Treatment for late-stage breast cancer can include a combination of:

• Chemotherapy: Oral or IV medications that are toxic to tumor cells
• Hormonal therapies: Drugs that lower estrogen levels or block estrogen receptors from allowing the cancer cells to grow
• Targeted therapies: Drugs that target your tumor’s specific gene mutations
• Immunotherapy: Medications that stimulate your immune system to recognize and attack cancer cells
• Radiation: The use of high-energy rays to kill tumor cells and shrink tumors
• Surgery: To remove a cancerous tumor or lymph nodes (uncommon with stage IV; more common in stages I, II, and III)
• Clinical trials: Studies of new medications, treatments, and other therapies offer hope for better outcomes

What are the Side Effects of Kisqali?

Dr. Eleonora Teplinsky, head of Breast Medical Oncology at Valley Health System, told SurvivorNet that Kisqali can come with a range of potential side effects — and emphasized the importance of discussing them thoroughly with a doctor before starting treatment.

She said some of the most common symptoms include:

• Low white blood cell counts, such as neutropenia (which can cause fever, chills, cough, and more)
• Nausea
• Vomiting
• Diarrhea
• Constipation
• Fatigue
• Hair thinning

“The side effects look different in every single person,” Dr. Teplinsky explained. “It’s sometimes hard to know how someone will tolerate the medication until we actually start it.”

She noted that patients should understand they may be on Kisqali for years, which means a symptom like diarrhea could persist long‑term. That’s why she encourages patients to weigh these possibilities with their doctor when deciding whether the drug’s benefits outweigh its risks.

For some people — especially those at high risk of recurrence — the potential benefit may clearly surpass the downsides. But, she added, “I think it’s a really hard decision for someone whose risk is a little bit lower to begin with.”

Ultimately, she said, “How you navigate that is really going to be an individual conversation between patient and doctor, balancing all of those side effects with the benefit.”

And if symptoms do arise, she urges patients to speak up. Doctors can help manage side effects so patients maintain a better quality of life while on treatment.

How Does Kisqali Work? Why Is It Paired With Endocrine Therapy?

Cancer cells grow by repeatedly moving through a tightly controlled series of steps known as the cell cycle. This process is complex and highly regulated — dozens of proteins must switch on at the right moment for a tumor cell to successfully divide.

Among the most important of these proteins are cyclin‑dependent kinases (CDKs), including CDK4/6. Because CDKs drive key checkpoints in the cell‑cycle pathway, they make strong targets for anti‑cancer drugs like CDK4/6 inhibitors, including Kisqali.

 

Kisqali, however, isn’t enough on its own. When CDKs are blocked, cancer cells can activate other growth‑promoting proteins to compensate — essentially finding a workaround that weakens the drug’s effect.

To counter this, clinicians often pair Kisqali with endocrine therapy, another major treatment class for breast cancer.

Endocrine therapy works by blocking hormones such as estrogen and progesterone, which fuel the growth of hormone‑receptor‑positive (HR+) breast cancers. These cancers rely on estrogen or progesterone binding to receptors (ER or PR) on the tumor cell surface. When those hormones are shut off, the cancer loses a critical growth signal.

By combining Kisqali with endocrine therapy, doctors create a coordinated, multi‑layered attack on the cancer — one that’s far harder for tumor cells to bypass.

Questions for Your Doctor

• Would combining Kisqali with endocrine therapy be appropriate for my type of breast cancer, and what benefits could I realistically expect?
• What side effects should I watch for with Kisqali, and how can we manage them if they become difficult?
• How long might I need to stay on Kisqali and endocrine therapy, and what does long‑term treatment usually look like?
• If my cancer tries to ‘work around’ CDK4/6 inhibition, how will we know, and what other treatment options would be available?

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