Six years ago, John P. Plastaras, MD, chief of radiation oncology and associate professor at the Hospital of the University of Pennsylvania, was called in by a colleague to see a non-Hodgkin lymphoma (NHL) patient with a mass in her upper chest area that was pressing on her airways. The patient was due to receive a chimeric antigen receptor (CAR) T-cell (CAR-T) therapy as part of a trial, but the physicians worried that her relapsed/refractory disease was progressing too rapidly to be able to wait the few weeks for her CAR-T cells to be manufactured.
Upon his colleague’s suggestion, Dr Plastaras proceeded to radiate the mass and control its growth until she could receive the immunotherapy. “While she was waiting for her cells, every day she was coming in for radiation treatments, and we were able to control this [mass],” he recalled. The patient indeed survived long enough to receive CAR-T treatment and ended up doing well on the immunotherapy. She is still in remission without experiencing recurrence or significant toxicities.
That spurred several studies by Dr Plastaras and his colleagues to explore the safety and effectiveness of using radiotherapy (RT) in patients with NHL with rapidly progressing disease to bridge the gap between leukapheresis and CAR-T infusion.
Now, a small, single-center retrospective analysis of hospitalization data suggests that radiation can be safely sequenced prior to the receipt of CAR-T in patients with relapsed/refractory NHL. The results, published recently in the International Journal of Radiation Oncology, Biology and Physics, also raised the question of whether using radiation as a bridging therapy to CAR-T could even reduce the toxicity associated with the immunotherapy.1
“The study . . . demonstrated that bridging RT appears to be safe, as it does not appear to negatively impact outcomes nor increase the incidence of severe toxicity,” noted Chelsea Pinnix, MD, PhD, associate professor and residency program director in the department of radiation oncology at the University of Texas MD Anderson Cancer Center, who has collaborated with Dr Plastaras in the past but wasn’t involved in the current study. “This is reassuring and suggests that oncologists should consider RT as a therapeutic option when bridging therapy is deemed necessary.”
The study focused on 31 relapsed/refractory NHL patients, 18 of whom received axicabtagene ciloleucel (axi-cel; Yescarta®) as inpatients, and 13 — mostly outpatients — received tisagenlecleucel (tisa-cel; Kymriah®) between August 2018 and February 2019.
Dr Plastaras and his colleagues categorized the patients in 2 groups. The first comprised 5 patients who had received radiation therapy less than 30 days prior to CAR-T infusion, most frequently to treat painful sites of disease. The second included 7 who had undergone radiation more than 30 days prior and 19 who had not received any radiation.
On average, the patients’ total duration of infusion admission was 20 days for the first group and 24 days for the second. The average duration of hospitalization for axi-cel recipients overall — including infusion-related as well as unplanned hospitalizations — was 20 days for patients in the first group, and 34 days in the second group. And while no patients in the first group required an unplanned hospitalization irrespective of the CAR-T product, 10 patients (5 axi-cel recipients and 4 tisa-cel patients) in the second group required an unplanned hospitalization.