George YancopoulosRegeneron

  • Biotech giant Regeneron has a cancer drug in the works that could be a very big deal.
  • The drug, cemiplimab, is a checkpoint inhibitor, a kind of drug that's part of a new class of cancer medications known as immunotherapy. 
  • There are already a handful of competitors that have gotten their versions of the drug approved, but that hasn't stopped Regeneron from pursuing it.
  • Regeneron chief scientific officer George Yancopoulos told Business Insider that's because of the company's approach. "We didn't just do what everybody else is doing, we actually thought about it,"   Yancopoulos said. 


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A relatively new field of cancer treatments is heating up.

Known as cancer immunotherapy, the treatments harness the power of the immune system to help it identify and knock out just the cancerous cells.

There's been a lot of success in one kind of immunotherapy called checkpoint inhibitors. Checkpoint inhibitors were first approved to treat melanoma — having remarkable success in people like President Jimmy Carter — and have since gone on to tackle lung cancer and bladder cancer, among other types of cancer.

To date, there have been six approved, five of which have to do with the proteins PD-1 (short for programmed cell death 1) and PD-L1, which are key in telling the body's immune system to react to a cancer cell or not.

Drugmaker Regeneron hopes its version, cemiplimab, will be one of the next approved. But it's taking a different approach. Cemiplimab, a drug that targets the PD-1 protein, is first being tested in cutaneous squamous cell carcinoma, a common form of skin cancer.

That's a departure from melanoma, the cancer type the other two PD-1 checkpoint inhibitors started with. Regeneron president and chief scientific officer Dr. George Yancopoulos told Business Insider that's because of the way the immune system reacted in people who had transplants.

"We didn't just do what everybody else is doing," Yancopoulos said. "We actually thought about it."

Cancer immunotherapyReuters

Cancers driven by the immune system

There's a strong link between squamous cell carcinoma and the immune system. A paper published in the New England Journal of Medicine in 2003 said that skin cancers — specifically squamous cell and basal-cell carcinoma — are the most common malignant conditions that affect transplant patients. The incidence of the cancer is also connected to the immuno-suppressant treatments transplant recipients receive so they don't reject the new organ.

"No solid tumors are really dramatically elevated in immuno-suppressed people, meaning the immune system does not normally control lung cancer, doesn't normally control melanoma, doesn't normally control these other cancers," Yancopoulos said. "But it must control this because there's a 75-fold increase in this cancer in transplant patients."

If it turns out that finding the cancers that are driven by the immune system is key to getting immunotherapy-based drugs to work for more patients, that could lead to more frequent use over other treatments and possibly better results. One of the things that's held these treatments back is that while it's had a good effect in people like Carter, the majority of people who get the treatment don't respond. For example, roughly 30% of metastatic melanoma patients using the PD-1 checkpoint inhibitor Keytruda respond completely. That's still better than the average response rate of chemotherapy treatments on their own in cases of metastatic melanoma.

In December, Regeneron said that in a phase 2 trial of 82 patients, cemiplimab had an overall response rate (meaning the cancer responded and shrank by a certain amount) in 46% of patients.

Should cemiplimab get approved, it would go up against tough competition. Opdivo and Keytruda, the two PD-1 drugs that have been approved, are both approved to treat melanoma, lung cancer, head and neck squamous cell carcinoma, among other cancer types.

Opdivo and Keytruda are the two best-selling checkpoint inhibitors. Opdivo made $4.9 billion in sales in 2017, while Keytruda made $3.8 billion.

Regeneron and its partner Sanofi are planning to file cemiplimab for FDA approval in the first quarter of 2018.

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