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Dr. Sanda Cohen was successfully treated with Keytruda for lung cancer 3 years ago. Photo courtesy of Real Chemistry.
  • Immunotherapies treat cancer by harnessing the power of the body’s immune system.
  • Keytruda has been one of the more successful immunotherapies. It’s now used to treat 16 types of cancer.
  • Two weeks ago, federal authorities approved the use of Keytruda to treat a common type of kidney cancer.
  • Immunotherapies can have side effects, but experts say they are providing hope for people with cancer.

Three years ago, after a stubborn cough landed her in the emergency room, Dr. Sanda Cohen made the transition from doctor to patient.

Cohen, 64, a pediatrician from Louisville, Kentucky, who’s married with three sons and three grandchildren, thought her ailment was just a severe cold.

But after undergoing tests, she was diagnosed with stage 4 lung cancer on Thanksgiving weekend in 2018.

Cohen’s doctors told her she should consider Keytruda, a relatively new immunotherapy treatment that was showing real promise.

Cohen didn’t hesitate. Within just weeks, she began Keytruda. And within 3 months, her tumors had shrunk by 50 percent.

Three years later, Cohen continues to receive Keytruda every 3 weeks and is doing well.

“It’s an incredible drug,” Cohen told Healthline. “Please take it if you have the option. I would’ve lived just 4 to 6 months if not for Keytruda.”

The development this past decade of cancer immunotherapies has seen several triumphs like Keytruda.

Drugs that harness the body’s immune system to fight cancer have begun to change the paradigm of cancer treatment.

But it’s still a relatively new field. There have been some bumps along the road.

CAR T-cell immunotherapy, for example, is a promising treatment. In some cases, it can even cure certain blood cancers.

However, there have been some safety concerns with CAR-T, from cytokine release syndrome to neurotoxicity.

But the safety profile of each subsequent generation of CAR-T appears to improve on the last.

Keytruda is certainly one of immunotherapy’s success stories.

More than 800,000 people worldwide have been treated with the drug, said a spokesman for Merck, the drug company that continues to develop the drug.

Healthline first wrote about Keytruda 3 years ago. The progress since has been unprecedented in lung and many other cancers.

A so-called anti-PD-1 therapy, Keytruda now provides 33 indications in 16 different cancers, according to Merck.

Two weeks ago, the Food and Drug Administration (FDA) announced the approval of Keytruda for the adjuvant treatment of people with renal carcinoma, the most common type of kidney cancer.

The multicenter, randomized, double-blind, placebo-controlled clinical trial included 994 participants.

Keytruda is used in kidney cancer as an adjuvant treatment, which means it’s an additional treatment given after the primary treatment (surgery, etc.) to lower the risk that the cancer will return.

Before this approval, people with renal carcinoma had few options.

The trial, KEYNOTE-564, which was published in the New England Journal of Medicine, was led by Dr. Toni K. Choueiri, a medical oncologist at the Dana-Farber Cancer Institute in Boston.

“Recurrence following surgery is common in renal cell carcinoma and despite decades of research, limited treatment options existed for patients whose cancer returned,” Choueiri said in a statement.

Choueiri noted that participants in the study demonstrated a statistically significant improvement in disease-free survival, reducing the risk of disease recurrence or death by 32 percent compared with placebo.

He said Keytruda provides a “new treatment option and potentially fundamental change in how we treat patients with kidney cancer considered at high risk of relapse.”

Keytruda, which is the drug that former President Jimmy Carter says made his melanoma disappear, is used to treat many types of cancer — both by itself and in combination with other treatments.

Keytruda is neither a chemotherapy nor a radiation therapy. It’s a type of immunotherapy called a checkpoint inhibitor that helps the body’s immune system detect and fight cancer cells.

Keytruda is a PT-1 inhibitor. PD-1 and PD-L1 are types of proteins found on cells in your body.

The PD-1 protein is found on immune cells called T cells. It normally acts as a type of “off switch” that helps keep the T cells from attacking other cells in the body.

Keytruda blocks the PD-1 pathway to help immune cells kill cancer cells better.

These include cancers that express the protein PD-L1, that have certain mutations (changes) in genes involved in DNA repair, or that have a high number of tumor mutations.

Keytruda is tolerated well by most people who use it.

Some common side effects include stomach pain, muscle pain, hair loss, constipation, cough, diarrhea, fever, loss of appetite, nausea, and rash.

Less common and more severe side effects include hepatitis, nephritis, arthritis, uveitis, pancreatitis, pneumonitis, myasthenia gravis, and allergic reaction.

When used as an initial therapy, Keytruda plus chemotherapy has been shown to help people with advanced non-squamous non-small cell lung cancer live longer than using chemotherapy alone.

In one study, half of the participants receiving Keytruda and chemotherapy were alive without their cancer spreading, growing, or getting worse at more than 8 months, compared with about 5 months for people treated with the chemotherapy regimen alone.

Cancer did not progress in 40 percent of participants receiving Keytruda plus chemotherapy compared with 19 percent of participants receiving chemotherapy alone.

Dr. Scot Ebbinghaus, vice president of oncology clinical research at Merck, told Healthline that working with Keytruda has been the highlight of his career.

“I’ve been doing cancer research for 30 years, and doing clinical cancer work for 20 years, and working on Keytruda has been a once in a lifetime opportunity, maybe even two or three lifetimes,” Ebbinghaus said.

Dr. Rana R. McKay, an oncologist and associate professor of medicine at UC San Diego Health, works in kidney cancer, prostate cancer, and other types of cancer.

She led much of the Keytruda kidney cancer trial’s data interpretation as part of the American Society of Clinical Oncology’s plenary discussion as well as the New England Journal of Medicine commentary on the issue.

McKay said that Opdivo, an immunotherapy from Bristol Myers Squibb, is on par with Keytruda as a significant immunotherapy.

And for specific diseases, she said, the addition of Yervoy, also an immunotherapy from Bristol Myers Squibb, has “driven long-term durable disease response.”

McKay told Healthline that the success of the Keytruda trial for kidney cancer is good news, but more work needs to be done.

“This is the first of a series of trials that will take place over the next couple of years,” she said.

“The goal is to change how we treat kidney cancer, to change our approach. More long-term follow-up is needed, but we don’t want to just delay recurrence. The hope is to prevent the cancer and try to cure more patients and never recur,” she added.

McKay noted that in clinical trials she runs that involve immunotherapies, there’s often a noticeable positive attitude among the participants.

In a CAR T-cell trial she is conducting with Poseida Therapeutics for people with prostate cancer, she said, “There is a hope and understanding that while this drug has a risk, it also has a high reward.”

There is something inherently optimistic about immunotherapy clinical trials, she said.

“The patients have hope that this could be a very promising therapy,” McKay said. “With immunotherapy, they feel like they are in the fight.”