Please ensure Javascript is enabled for purposes of website accessibility

Merck's Keytruda Helps Treat an Aggressive Form of Breast Cancer

By Brian Orelli, PhD - Feb 12, 2020 at 12:39PM

You’re reading a free article with opinions that may differ from The Motley Fool’s Premium Investing Services. Become a Motley Fool member today to get instant access to our top analyst recommendations, in-depth research, investing resources, and more. Learn More

Another win for the seeming unstoppable drug -- this time in metastatic triple-negative breast cancer.

Chalk up another win for Keytruda, Merck's (MRK 0.83%) cancer drug that seems to be able to be useful in treating almost every type of cancer it's tested against. The most recent results come from a late-stage clinical trial in patients with metastatic triple-negative breast cancer with tumors that express the protein that Keytruda blocks.

Merck said results from the Keynote-355 study showed that Keytruda plus chemotherapy delayed cancer progression and kept patients alive longer than chemotherapy alone. The company did not disclose how much better the combination performed, however; it's saving the details for a presentation at a future medical meeting.

This was only an interim peek at the data, and the clinical trial will continue so it can measure overall survival, which is arguably a more important endpoint for patients and doctors. In the meantime, the pharmaceutical company plans to discuss the results with the FDA and other regulators to potentially get the drug approved to treat this type of cancer.

Woman in a headscarf holding hands with another woman

Image source: Getty Images.

Triple-negative breast cancer gets its name because the cancer cells lack receptors for both estrogen and progesterone, and do not produce excessive amounts of human epidermal growth factor receptor 2 (HER2). A large share of other cancer drugs disrupt the effects of estrogen, progesterone, or HER2 on breast cancer cells, and are therefore ineffective against the triple-negative variety. This limits the treatment options, which means that triple-negative breast cancer tends to be particularly aggressive and has a high recurrence rate.

Keytruda blocks the interaction of a protein on immune cells called programmed cell death 1 (PD-1) with a protein expressed on cancer cells (PD-L1) that tells immune cells not to attack them. By blocking the interaction, Keytruda induces the immune cells to attack the tumor. Since the mechanism is a fairly universal way that tumors avoid being targeted by the immune system, Merck has been able to show that the drug improves outcomes in more than a dozen different types of cancer.

Invest Smarter with The Motley Fool

Join Over 1 Million Premium Members Receiving…

  • New Stock Picks Each Month
  • Detailed Analysis of Companies
  • Model Portfolios
  • Live Streaming During Market Hours
  • And Much More
Get Started Now

Stocks Mentioned

Merck & Co., Inc. Stock Quote
Merck & Co., Inc.
$93.08 (0.83%) $0.77

*Average returns of all recommendations since inception. Cost basis and return based on previous market day close.

Related Articles

Motley Fool Returns

Motley Fool Stock Advisor

Market-beating stocks from our award-winning service.

Stock Advisor Returns
S&P 500 Returns

Calculated by average return of all stock recommendations since inception of the Stock Advisor service in February of 2002. Returns as of 05/28/2022.

Discounted offers are only available to new members. Stock Advisor list price is $199 per year.

Premium Investing Services

Invest better with The Motley Fool. Get stock recommendations, portfolio guidance, and more from The Motley Fool's premium services.