In this study, patients could receive bridging therapy to keep their disease stable while KTE-X19 was being manufactured. There were 25 patients who received bridging therapy, which consisted of ibrutinib (n = 14), acalabrutinib (n = 5), dexamethasone (n = 12), and/or methylprednisolone (n = 2). Six patients received both BTK inhibitors and steroids.
All patients received conditioning with fludarabine and cyclophosphamide, followed by a single infusion of KTE-X19 at 2x106.
Efficacy
Sixty patients were evaluable for efficacy, and the median follow-up was 12.3 months (range, 7.0-32.3 months).
The overall response rate was 93%, with 67% of patients achieving a complete response and 27% achieving a partial response. Three percent of patients had stable disease, and 3% had progressive disease.
“The overall response rate was consistent across key subgroups, without any statistical difference,” Dr. Wang said. “This includes Ki-67, MIPI, and prior use of either steroids or bridging therapy.”
The median time to response was 1.0 month, and the median time to complete response was 3.0 months. Responses deepened over time, with 35% of patients converting from a partial response to a complete response, and 5% converting from stable disease to complete response.
The median duration of response has not been reached. At last follow-up, 57% of all patients and 78% of complete responders were still in response.
The median progression-free and overall survival have not been reached. At 12 months, the progression-free survival rate was 61%, and the overall survival rate was 83%.
Safety
All 68 patients were evaluable for safety. The most common adverse events were pyrexia (94%), neutropenia (87%), thrombocytopenia (74%), anemia (68%), and hypotension (51%).
Grade 3/4 adverse events included pyrexia (13%), neutropenia (85%), thrombocytopenia (51%), anemia (50%), hypotension (22%), hypoxia (21%), hypophosphatemia (22%), fatigue (1%), and headache (1%).
There were two grade 5 treatment-related adverse events – organizing pneumonia on day 37 and staphylococcal bacteremia on day 134.
Cytokine release syndrome (CRS) occurred in 91% of patients, with 15% experiencing grade 3 or higher CRS. Patients were treated with tocilizumab or corticosteroids, and all CRS events resolved.
Neurologic adverse events occurred in 63% of patients, with grade 3 or higher events occurring in 31%. Neurologic events were treated with tocilizumab or corticosteroids, and 86% of neurologic events resolved.
This trial was sponsored by Kite, a Gilead company. Dr. Wang reported financial relationships with Kite and other companies.
SOURCE: Wang M et al. ASH 2019. Abstract 754.