Eight of 14 patients in the first clinical trial of personalized cellular therapy for chronic lymphocytic leukemia (CLL) responded to the therapy, with some complete remissions continuing beyond 4.5 years. These results, published in Science Translational Medicine (2015; 10.1126/scitranslmed.aac5415), represent the most mature data from clinical trials of an approach known as CTL019.

The trial was conducted at the University of Pennsylvania in Philadelphia. A team from Penn’s Abramson Cancer Center and the Perelman School of Medicine developed the CTL019 approach.

In 2011, the research team published initial findings from the first three patients enrolled in the trial. Two of those patients had complete responses, and their leukemia remains in remission today, more than 4.5 years after receiving the therapy. The first patient to receive the therapy recently marked 5 years cancer-free.

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“The durability of the remissions we have observed in this study are remarkable and have given us great hope that personalized cell therapies are going to be important options for patients whose cancers are no longer treatable with standard approaches,” said lead author David L. Porter, MD, the Jodi Fisher Horowitz Professor in Leukemia Care Excellence and director of Blood and Marrow Transplantation in Penn’s Abramson Cancer Center. “The patients in this study are pioneers, whose participation has given us a foundation of knowledge and experience on which to build this new approach to help more patients.”

The new study details the completed, 14-patient pilot trial of CTL019 for CLL, which began in the summer of 2010. The overall response rate was 57%. All patients who received the experimental therapy, which is made from their own immune cells, had cancer that had relapsed or continued to progress after receiving multiple conventional FDA-approved therapies, and few were eligible for bone marrow transplants.

Four patients (29%) in the study achieved a complete remission. One patient died while in remission at 21 months after the therapy due to infectious complications after removal of a basal cell carcinoma on his leg. The three other patients remained alive at the time of this analysis with no evidence of leukemia at 28, 52, and 53 months after receiving their infusions, with no further therapy.

An additional four patients (29%) achieved partial responses to the therapy, with responses lasting a median of 7 months. During the period analyzed, two of these patients had died of disease progression at 10 and 27 months after receiving CTL019, and one died after suffering a pulmonary embolism 6 months after T cell infusion. One patient’s disease progressed at 13 months but remained alive on other therapies at 36 months after receiving the therapy.

Six patients (43%) did not respond to the therapy and progressed within 1 to 9 months; tests revealed that the modified T cells did not expand as robustly in these patients as in those who experienced remissions. Two of these subjects later died from their disease or complications of other therapies, and four are receiving other types of treatment.

“Importantly, our tests of patients who experienced complete remissions showed that the modified cells remain in patients’ bodies for years after their infusions, with no sign of cancerous or normal B cells,” said the study’s senior author, Carl H. June, MD, the Richard W. Vague Professor in Immunotherapy in Penn’s department of Pathology and Laboratory Medicine and director of Translational Research in the Abramson Cancer Center.