In an ongoing, phase I trial of chimeric antigen receptor (CAR) T-cell therapy in patients with relapsed/refractory myeloma, 33 out of 35 patients achieved complete response (CR) or very good partial response (VGPR), for a clinical remission rate of 94 percent. Author Wanhong Zhao, MD, PhD, from the Second Affiliated Hospital of Xi’an Jiaotong University in Shaanxi, China, who presented results as a late-breaking abstract at the 2017 ASCO Annual Meeting, called the findings an “encouraging breakthrough” for myeloma patients.
“Although recent advances in chemotherapy have prolonged life expectancy in multiple myeloma, this cancer remains incurable,” Dr. Zhao said during a press briefing. “It appears that with this novel immunotherapy there may be a chance for cure in multiple myeloma, but we will need to follow patients much longer to confirm that.”
Dr. Zhao and researchers evaluated LCAR-B38M CAR T cells targeting B-cell maturation antigen (BCMA). The median number of infused cells was 4.7×106/kg (range = 0.6-7.0×106/kg).
Preliminary safety and efficacy results from another phase I study of BCMA-targeting CAR T-cell therapy for patients with myeloma were presented at the 2016 ASH Annual Meeting. Adam D. Cohen, MD, from the Perelman School of Medicine at the University of Pennsylvania in Philadelphia, and colleagues reported a complete remission rate of 44 percent, including one patient who has been in stringent complete remission for 12 months.
The current trial followed patients for a median of 208 days (range = 62-321 days), finding an objective response rate (ORR) of 100 percent. Thirty-three patients (94%) achieved CR or VGPR within 2 months of CAR T-cell infusion.
At the time of data presentation, 19 patients had been followed for longer than 4 months, which the researchers selected as a pre-specified point for efficacy assessment (per International Myeloma Working Group consensus guidelines). In this subset of patients, 14 had achieved stringent CR, four had achieved VGPR, and one had achieved PR.
One patient in VGPR had evidence of disease progression, when an extramedullary lesion reappeared 3 months after a negative CT scan, Dr. Zhao noted. However, there have been no relapses among patients in stringent CR. Five patients have been followed for more than a year (12-14 months), and all remain in stringent CR and free of minimal residual disease.
“LCAR-B38M technology not only demonstrates outstanding efficacy, but also suggests a great safety profile,” Dr. Zhao said. The most common adverse event (AE) associated with CAR T-cell therapy, cytokine release syndrome (CRS), occurred in 85 percent of the patient population, but was transient in all patients. CRS was successfully managed with the IL-6 receptor tocilizumab.
Other AEs were “mild and manageable,” the authors reported, and included fever, hypotension, and dyspnea. No patients experienced neurologic AEs, which have been serious complications in other trials of CAR T-cell therapies.
The study is limited by its small patient population and short follow-up. The researchers plan to eventually enroll a total of 100 patients, and, “in early 2018, we also plan to launch a similar clinical trial in the United States,” Dr. Zhao said. “Looking ahead, we would like to explore whether BCMA CAR T-cell therapy benefits patients who are newly diagnosed with multiple myeloma.”
Fan F, Zhao W, Liu J, et al. Durable remissions with BCMA specific chimeric antigen receptor (CAR)-modified T cells in patients with refractory/relapsed multiple myeloma. Abstract #LBA3001. Presented at the 2017 ASCO Annual Meeting, June 6, 2017; Chicago, Illinois.