Before Chase, five patients had received the therapy with four having excellent results, but the doctors had never treated a foreign citizen, Chen said.

"His illness was rather serious, and it was already late stage. The therapy is still in experimental phase, so we were under a lot of pressure," she said.

CAR-T, chimeric antigen receptor, involves removing T-cells from a patients' blood, reprogramming them into the body to attack infected cells.

"T-cells are like the police force in our body. CAR-T arms the cells with positioning and ballistic device. When the T-cells are re-injected in the body, these cell police can precisely locate the cancer cells and terminate them," she said. "CAR-T has received a lot of attention, but using CAR-T to treat multiple myeloma is still in the trial phase and not yet mature."

Chase started CAR-T treatment on Aug. 11, and doctors will continue to monitor his health, she said.