Bridging Radiotherapy Prior to Chimeric Antigen Receptor T-Cell Therapy for B-Cell Lymphomas: An ILROG Multi-Institutional Study

PURPOSE/OBJECTIVE(S)

To report an ILROG multi-institutional analysis of bridging radiotherapy (BRT) prior to CD19-targeting chimeric antigen receptor T-cell (CAR T) therapy for relapsed/refractory aggressive B-cell lymphomas (BCL).

MATERIALS/METHODS

Weretrospectively reviewed 115 patients (pts) with diffuse large BCL (n = 101, 88%), primary mediastinal BCL (n = 11, 10%), mantle cell lymphoma (n = 2, 2%), and T-cell/histiocyte rich large BCL (n = 1, 1%) who received BRT prior to commercial CAR T from 2018-2020 across 6 institutions. BRT toxicities were graded per CTCAE v5.0, cytokine release syndrome (CRS) per ASTCT, and immune effector cell-associated neurotoxicity syndrome (ICANS) per either ASTCT or CTCAE v5.0. Progression-free survival (PFS) and overall survival (OS), measured from CAR T infusion, were estimated using the Kaplan-Meier method. PFS was modeled using Cox regression with stepwise variable selection.

RESULTS

BRTwas given prior to axicabtagene ciloleucel (axi-cel; n = 82, 71%), tisagenlecleucel (tisa-cel; n = 31, 27%), or brexucabtagene autoleucel (n = 2, 2%). Median age was 62 years with median of two prior lines of therapy. Most pts had advanced stage III/IV disease at leukapheresis (n = 87, 76%), elevated pre-leukapheresis LDH (n = 73, 63%), and bulky disease (n = 55, 50%) (1 lesion ≥7.5 cm). 78 pts (68%) had extranodal disease, 12 (10%) had central nervous system (CNS) involvement, and 36 (31%) had bone involvement. Systemic bridging therapy was given to 42 pts (37%). Median intervals from leukapheresis to BRT start and from BRT completion to CAR T infusion were 5 days (IQR -6, 11) and 12 days (IQR 9, 23), respectively. BRT was delivered to 163 total sites; most commonly the abdomen/pelvis (n = 58, 50%), head/neck (n = 34, 30%), thorax (n = 20, 17%), extremity/soft tissue (n = 20, 17%), and CNS (n = 13, 11%). Median biologically effective dose was 31.3 Gy (IQR 24, 39). Most common regimen was 30 Gy in 10 fractions (n = 27, 17%). 40 pts (35%) received comprehensive BRT (to all active lesions). There were no grade ≥3 BRT toxicities. Grade ≥3 CRS occurred in 9 pts (8%), including 8/82 (10%) after axi-cel and 1/31 (3%) after tisa-cel. Grade ≥3 ICANS occurred in 23 pts (20%), including 22/82 (27%) after axi-cel and 1/31 (3%) after tisa-cel. Median follow up was 26.9 months. 1- and 2-year OS rates were 60% and 49%. 1- and 2-year PFS rates were 41% and 35%. Comprehensive BRT associated with superior PFS (HR 0.34, 95% CI 0.19-0.62, p<0.001) in a multivariable model with age ≥60, ECOG ≥2, advanced stage, CNS disease, pre-leukapheresis LDH, and axi-cel.

CONCLUSION

In this multi-institutional study, pts receiving BRT prior to CAR T therapy for BCL frequently had bulky disease yet experienced favorable PFS and OS. There were no serious toxicities attributable to BRT, and the rates of CRS and ICANS are comparable to those after CAR T alone. Comprehensive BRT associated with superior PFS.

Bendamustine is safe and effective for lymphodepletion before tisagenlecleucel in patients with refractory or relapsed large B-cell lymphomas

BACKGROUND

Anti-CD19 chimeric antigen receptor T-cell immunotherapy (CAR-T) is now a standard treatment of relapsed or refractory B-cell non-Hodgkin lymphomas; however, a significant portion of patients do not respond to CAR-T and/or experience toxicities. Lymphodepleting chemotherapy is a critical component of CAR-T that enhances CAR-T-cell engraftment, expansion, cytotoxicity, and persistence. We hypothesized that the lymphodepletion regimen might affect the safety and efficacy of CAR-T.

PATIENTS AND METHODS

We compared the safety and efficacy of lymphodepletion using either fludarabine/cyclophosphamide (n = 42) or bendamustine (n = 90) before tisagenlecleucel in two cohorts of patients with relapsed or refractory large B-cell lymphomas treated consecutively at three academic institutions in the United States (University of Pennsylvania, n = 90; Oregon Health & Science University, n = 35) and Europe (University of Vienna, n = 7). Response was assessed using the Lugano 2014 criteria and toxicities were assessed by the Common Terminology Criteria for Adverse Events (CTCAE) version 5.0 and, when possible, the American Society for Transplantation and Cellular Therapy (ASTCT) consensus grading.

RESULTS

Fludarabine/cyclophosphamide led to more profound lymphocytopenia after tisagenlecleucel infusion compared with bendamustine, although the efficacy of tisagenlecleucel was similar between the two groups. We observed significant differences, however, in the frequency and severity of adverse events. In particular, patients treated with bendamustine had lower rates of cytokine release syndrome and neurotoxicity. In addition, higher rates of hematological toxicities were observed in patients receiving fludarabine/cyclophosphamide. Bendamustine-treated patients had higher nadir neutrophil counts, hemoglobin levels, and platelet counts, as well as a shorter time to blood count recovery, and received fewer platelet and red cell transfusions. Fewer episodes of infection, neutropenic fever, and post-infusion hospitalization were observed in the bendamustine cohort compared with patients receiving fludarabine/cyclophosphamide.

CONCLUSIONS

Bendamustine for lymphodepletion before tisagenlecleucel has efficacy similar to fludarabine/cyclophosphamide with reduced toxicities, including cytokine release syndrome, neurotoxicity, infectious and hematological toxicities, as well as reduced hospital utilization.

Effect of rituximab (R) on clinical outcomes after autologous stem cell transplantation (ASCT) in pts with relapsed or refractory diffuse large B-cell lymphoma (DLBCL)

8122

Background: First-line chemotherapy cures ∼50% of pts with DLBCL, while salvage therapy followed by ASCT can cure another ∼30%. R significantly improves response rates to 1st line therapy. This retrospective study was designed to test the hypotheses that: 1) ASCT is effective in pts relapsed after R-chemotherapy and 2) addition of R to salvage improves outcomes after ASCT. Methods: We identified 84 pts with relapsed/refractory DLBCL who underwent ASCT at our institution between 1990 and 2006. In all, 32% received a R-chemo 1st line regimen and 27% received R with salvage. The median age at ASCT was 49 yrs and the median time from diagnosis to ASCT was 16 mos. High-dose regimens included BCV (48%), BEAM (8%) and alkylator/TBI (20%). Results: Overall response rate (ORR) after ASCT was 52%, with 37% of pts in CR by day 100. Among those in CR, 16% had a CR pre-ASCT, 72% had a lesser response, and 9% were chemo-resistant. The addition of R to salvage (23/84 pts) was favorably associated with ORR after ASCT (OR: 5.2, 95% CI: 1.1 - 25, p=0.029), even in pts who had failed a prior R regimen (p=0.013). Other factors favorably associated with ORR were response to salvage (p=0.046) and time to ASCT >12 mos (p=0.017). At last f/u (med: 22 mos, iqr: 7 - 55 mos), event-free (EFS) and overall survival (OS) were both 35%. The only factor associated with EFS and OS in univariate and multivariate analyses was ORR after ASCT (HR: 0.16, 95% CI: 0.07 - 0.37, p<0.001 and HR: 0.12, 95% CI: 0.05 - 0.28, p<0.001 respectively). Age at ASCT, time to ASCT, year of ASCT, mobilization/conditioning regimen, and failure of a R-chemo regimen were not associated with EFS or OS. Conclusions: Pts with DLBCL who have failed a R-chemo first-line regimen derive an equal benefit from ASCT as pts who are R-naïve, with significant long-term EFS and OS. Additionally, inclusion of R in salvage therapy prior to ASCT provides superior response rates, even after a failed prior R-chemo regimen. These results confirm the benefit of ASCT for pts with DLBCL in the rituximab era and argue for the incorporation of R and related agents in studies of high-dose therapy and ASCT.

No significant financial relationships to disclose.

Outpatient autologous stem cell transplants for selected patients with myeloma: Morbidity, mortality, and duration of hospitalization

7104

Background: High-dose melphalan with autologous stem cell support improves survival for patients with myeloma but often requires prolonged inpatient hospitalization. Short hospitalization with close follow-up may reduce complications, cost, and duration of total hospitalization for selected patients with good performance status and social support. Methods: We reviewed all initial autologous transplants for myeloma from 1/03–4/06, categorized by length of initial hospitalization as brief stay (≤4 days) or prolonged stay (≥5 days). Clinical selection for a brief stay had been based on a combination of age; cardiac, pulmonary, and renal function; performance status; availability of caregivers at home; distance from our medical center; and patient preference. We reviewed the post-transplant course to 100 days and calculated cumulative hospitalization by adding length of initial hospitalization to that of subsequent readmissions within 100 days. Results: 148 patients received an initial transplant for myeloma: 64 were selected for brief stay and 84 for prolonged stay. There were no significant differences in age or in renal function, Durie-Salmon stage, or B2-microglobulin at diagnosis. Brief stay patients were discharged home after stem cell reinfusion, with first follow-up scheduled 3–14 days later. Care at home included a nurse visit after discharge, intravenous fluids and ondansetron, and oral antibiotics, with blood work twice weekly. 46% of brief stay patients required readmission during the first 100 days and had a median of 8.5 cumulative hospital days post-transplant, as compared to 18 days for prolonged stay patients (p=0.0001). There were fewer documented infections among brief stay patients (29.7% vs 50.0%, p=0.01) and fewer admissions to intensive care units (0 vs 6.0%, p=0.047). The groups had similar rates of bleeding (1.6% vs 4.8%, p=0.3) and thrombosis (3.1% vs 8.3%, p=0.2). No patients in the brief stay group died within 100 days, while mortality in the prolonged stay group was 4.8% (p=0.08). Conclusion: Selected patients receiving an autologous stem cell transplant for treatment of myeloma can be managed with brief initial hospitalization and outpatient follow-up, with low morbidity and mortality.

No significant financial relationships to disclose.

Prognostic value of FDG-PET scan imaging in lymphoma patients undergoing autologous stem cell transplantation

We conducted a retrospective analysis of 50 lymphoma patients (Hodgkin's disease and non-Hodgkin's lymphoma) who had an 18F-fluoro-deoxyglucose positron emission tomography (FDG-PET) scan after at least two cycles of salvage chemotherapy and before autologous stem cell transplantation (ASCT) at our institution. The patients were categorized into FDG-PET negative (N = 32) and positive (N = 18) groups. The median follow-up after ASCT was 19 months (range: 3-59). In the FDG-PET-negative group, the median progression-free survival (PFS) was 19 months (range: 2-59) with 15 (54%) patients without progression at 12 months after ASCT. The median overall survival (OS) for this group was not reached. In the FDG-PET-positive group, the median PFS was 5 months (range: 1-19) with only one (7%) patient without progression at 12 months after ASCT. The median OS was 19 months (range: 1-34). In the FDG-PET-negative group, chemotherapy-resistant patients by CT-based criteria had a comparable outcome to those with chemotherapy-sensitive disease. A positive FDG-PET scan after salvage chemotherapy and prior ASCT indicates an extremely poor chance of durable response after ASCT.

Long-term event-free survivors after high-dose therapy and autologous stem-cell transplantation for low-grade follicular lymphoma

Although follicular lymphoma (FL) is generally responsive to conventional-dose chemotherapy, improved survival in patients with this disease has been difficult to demonstrate. High-dose chemo/radiotherapy followed by autologous stem-cell transplantation (ASCT) can improve response rates, although its effects on survival remain controversial. Between 1990 and 2003, we transplanted 49 patients with low-grade FL at our institution. Twenty-two patients (45%) had undergone histologic transformation at the time of ASCT. In all, 44 patients (90%) had relapsed disease and five patients (10%) were resistant to chemotherapy at the time of transplantation. After ASCT, 30 patients (61%) were in complete remission (CR). The median overall survival (OS) has not been reached, while the median event-free survival (EFS) is 2.4 years. At a median follow-up of 5.5 years (longest 12.4 years), a plateau has been reached with 56% of patients remaining alive, and 35% event-free. ASCT was well tolerated except for two (4%) treatment-related deaths. In multivariable analysis, CR after ASCT and age less than 60 years are the best predictors of EFS and OS. ASCT is thus a safe therapeutic approach in FL, resulting in long-term EFS and OS for some patients, even with transformed disease.