More Than 80% of Women With Early-Stage Triple-Negative Breast Cancer Experienced a Prolonged Event-Free Survival With Keytruda Plus Chemotherapy Regimen

Triple-negative accounts for between 10% and 20% of all breast cancers in the United States. Triple-negative means the three main types of receptors estrogen, progesterone and the HER2 protein do not fuel the cancer. Because of this, it cannot be treated with traditional hormonal therapy or medicines that target HER2 receptors. This has resulted in fewer treatment options for triple-negative breast cancer, until Keytruda.

There was a phase 3 clinical trial that preceded the FDA approval. However, the only thing said of the results at the time was that at the median follow-up of 39 months (about three and a half years), Keytruda showed a "significant" event-free survival benefit when compared to chemotherapy alone.

The Promise of Immunotherapy for Cancer Treatment

One oncologist, Dr. Sylvia Adams, who is the director of the Breast Cancer Center at NYU Langone's Perlmutter Cancer Center, said at the time that the approval "changes the standard of care" for triple-negative breast cancer patients; that was before we had the complete results regarding event-free survival for the trial.

Until now.

The final event-free survival numbers were published Thursday in the New England Journal of Medicine, and they are exactly what many oncologists have been saying: game-changing.

Final Event-Free Survival Numbers

Of the 1,174 participants in the randomized clinical trial, 784 received 200 milligrams of Keytruda every three weeks in addition to neoadjuvant chemotherapy four cycles of paclitaxel and carboplatin and then four cycles of doxorubicin or epirubicin plus cyclophosphamide (all chemotherapies). The other 390 people received chemotherapy with a placebo.

Patients then underwent surgery and received radiation therapy as indicated. Adjuvant treatment (after surgery) included up to nine cycles of Keytruda or placebo, depending on which randomized group the patient belonged to. The number of cycles varied depending on factors such as disease recurrence or unacceptable toxicity. (Keytruda is an anti-PD-1 monoclonal antibody administered intravenously.)

The median follow-up was 39.1 months, however, the estimated event-free survival at 36 months was a whopping 84.5% in the chemotherapy with Keytruda group, as compared to 76.8% in the chemotherapy with placebo group.

Related: Metastatic Triple-Negative Breast Cancer Treatments to Consider

"These data, which supported the FDA approval and updates to the NCCN (National Comprehensive Cancer Network) guidelines, establish that Keytruda plus chemotherapy as neoadjuvant therapy followed by adjuvant Keytruda could change clinical practice for the treatment of patients with high-risk early-stage TNBC," Dr. Peter Schmid, lead at the Centre for Experimental Cancer Medicine, Barts Cancer Institute in London, England, said in a prepared statement from Keytruda drugmaker, Merck.

"KEYNOTE-522 (the clinical trial name) is the first prospective randomized Phase 3 trial to show an improvement in event-free survival among patients with stage II and stage III TNBC," he added.

The Keytruda & Immunotherapy Revolution

While there are many immunotherapy options, Keytruda is revolutionizing the cancer treatment world as it is gaining more and more FDA approvals to treat various types of cancers. In fact, in 2021 alone, Keytruda was approved eight times to treat different types of cancers, from early-stage breast cancer to kidney cancer.

"Previously, (Keytruda) was used only for metastatic disease, but it's shown such a good response there (treating early-stage triple-negative breast cancer) that now is used for earliest-stage disease, not because they have metastasis, but because it's now been shown to reduce the risk of metastasis occurring," Dr. Wui-Jin Koh, senior vice president and chief medical officer at the National Comprehensive Cancer Network, tells SurvivorNet. (The approval Dr. Koh is talking about is this exact study we are writing about.)

Keytruda is Not for Everyone Immunotherapy Needs to be Tailored

While this drug is great, "Keytruda is not for everyone," Dr. Anna Pavlick, previously professor of medicine and dermatology at NYU Perlmutter Cancer Center and now a professor in the Division of Hematology & Medical Oncology at Weill Cornell Medicine, tells SurvivorNet.

She often has patients request the immunotherapy drug Keytruda in response to a commercial they have seen. However, it can be an effective immunotherapy, but in certain patients it may cause severe immune-related adverse effects.

The important thing is to talk to your doctor if you think Keytruda could be right for you.

Contributing: James Roland

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