The problem is that these chemicals can overwhelm the system. "We see this in the first one to three days after the altered T cells are infused," says Dr. Martin. "The cells go to the area where the myeloma is, and they grow and expand very quickly. So within 24 to 72 hours most people have symptoms of CRS. Those symptoms include a high fever of 101 to 103 degrees. And they may have low blood pressure or high blood pressure and shortness of breath. Most patients feel fatigued. It feels like you have a bad infection."

Other possible symptoms of CRS include headache, chills, scratchy throat, nausea, vomiting, diarrhea and muscle or joint pain. In addition, CRS can cause rapid heart rate. All of these symptoms are caused by the new T cells creating a storm inside the body.

How To Treat CRS

Most people who develop CRS will have mild to moderate symptoms, but sometimes CRS can be serious and even life-threatening. When symptoms occur, doctors follow their patients closely to make sure they are effectively managed.

"If the symptoms are mildmeaning that the temperature might rise but the blood pressure is fine and there's no change in the oxygen saturation in the bloodthen we can usually just give acetaminophen (Tylenol) to control the fever," says Dr. Martin. "But if the oxygen level gets a little bit low in the blood, some people will need oxygen support by either a nasal cannular or face mask. Or if the blood pressure gets a little low we give fluids or medication for that.”

The medication most often used to battle moderate to severe CRS is called tocilizumab, or "toci" for short. "Toci is a medicine that tries to turn off this really high cytokine storm, and it's pretty effective in most people," says Dr. Martin. The CRS symptoms generally last from four to seven days.

The Benefits Outweigh the Risks

CRS isn't the only side effect associated with CAR T-cell therapy. Patients may have neurologic events that can include brain injury or malfunction, confusion, aphasia (difficulty understanding or speaking), drowsiness, agitation, seizures, loss of balance and altered consciousness. The treatment can also lower white or red blood cell count. Most of these side effects will resolve on their own or can be managed with medication. But patients should always let their physician or care team know immediately if they are experiencing side effects of treatment.

While CRS can be severe, it is manageable. "We see it in 70 to 90 percent of patients with CAR T-cell therapy, but we know it's coming, and we know how to manage it," says Dr. Martin. And when it's over, he says, "what we're hoping is that you've had a good anti-cancer effect."

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