Outcomes with Bridging Radiation Therapy Prior to CAR-T Cell Therapy in Pts with Aggressive B Cell Lymphomas

PURPOSE/OBJECTIVE(S)

Select patient (pts) with relapsed/refractory aggressive B cell lymphoma may benefit from bridging radiation (bRT) prior to anti-CD19-directed chimeric antigen receptor T cell therapy (CART). Here, we examined pt and treatment factors associated with outcome after bRT and CART.

MATERIALS/METHODS

We retrospectively reviewed adults with DLBCL who received bRT prior to axicabtagene ciloleucel 11/2017-12/2022. Clinical/treatment characteristics, response, and toxicity were extracted. Progression free survival (PFS), disease specific survival (DSS) and overall survival (OS) were modeled using Kaplan-Meier for events distributed over time, or binary logistic regression for disease response. Fisher's Exact Test or Mann-Whitney U methods were used.

RESULTS

Among 40 pts, 11 (28%) had limited stage disease at apheresis, and 14 (35%) received bRT in addition to bridging systemic therapy. Thirty-two (80%) pts received bRT post-leukapheresis. bRT was delivered with a median dose of 30 Gy (range: 4-46) in 10 fractions (range: 2-23). Eighteen (45%) pts received <30 Gy. Twenty-two pts (55%) received bRT comprehensively to all sites of disease, including 9 pts who had limited stage. Eleven pts had bulky disease (≥ 10 cm) at the time of bRT. After CART, 4 pts (10%) experienced Grade ≥3 cytokine release syndrome (CRS), 16 (40%) had Grade ≥2 CRS, and 16 (38%) had Grade ≥3 neurotoxicity. Twenty-three pts (57.5%) had CR at 30 days post-CART infusion. Nine had PR (22.5%), of whom 2 pts eventually developed CR at three months and 1 at nine months. Eight pts (20%) had either PD or SD. Of 23 pts who experienced CR, 11 relapsed-6 at three months and 5 at six months. At a median follow up of 9.6 months (95% CI: 6.6-16.2), 22 pts relapsed: 6 (27.3%) in-field, 10 (5.5%) out-of-field, 4 (18.2%) both, and 2 (9.1%) unknown. The median PFS was 8.87 months and median OS was 22 months. PFS at 1 year was 70% (53-82) and at 2 years was 42% (27-57). OS at 1 and 2 years was 72.5% (56-84) and 51% (34-65), respectively. Seventeen pts (42.5%) remain alive at last follow-up, 13 (76.5%) of whom have no evidence of disease (NED). On univariate analysis, OS and PFS at 1 year were 67% (43-83) and 49% (27-68) for those who received RT comprehensively (n = 22), and 41.9% (19-64) and 33.3% (14-54) for those who did not (n = 18; both p≤0.03). Disease bulk (≥10 cm) was associated with significant decrement in DSS (p = 0.03), but not PFS (p = 0.16) or OS (p = 0.24). Among pts treated comprehensively with bRT (n = 22), there was no association of tumor bulk with OS, PFS, or DSS (p>0.2). IPI ≥3 was associated with worse DSS (p = 0.045) and trended towards worse PFS (p = 0.054), but not OS (p = 0.23). There was no difference in PFS, OS, or DSS between pts who received bRT or chemoRT (p>0.3).

CONCLUSION

bRT and CART is a good treatment strategy for select pts with aggressive B cell lymphoma. When feasible, and with a caveat that other variables influence patient disposition, bRT for CART is associated with improved outcomes after comprehensive RT to all sites of disease.

Outcomes and Toxicities in Patients with Diffuse Large B-Cell Lymphoma of the Gastrointestinal Tract

PURPOSE/OBJECTIVE(S)

Diffuse large B-cell lymphoma (DLBCL) involving the gastrointestinal (GI) tract is rare and long-term outcomes are not well defined. Combined modality therapy (CMT) with radiotherapy (RT) in addition to systemic therapy in this setting is not commonly pursued. We aim to characterize outcomes in patients with GI DLBCL treated with systemic therapy, with or without RT.

MATERIALS/METHODS

Patients diagnosed with DLBCL of the GI tract (with or without mesenteric involvement) treated at a single institution from 1988-2022 were retrospectively reviewed on an IRB-approved protocol. Clinical and treatment data were collected including adverse events (AE; acute vs late defined as before or 4 weeks after therapy end). Kaplan-Meier and Cox regression models were used to estimate survival.

RESULTS

Of 207 patients, 62% were male and median age at diagnosis was 63 (IQR 52-73). Gastric involvement was most common (n = 130, 63%), followed by small intestines (n = 48, 23%) and colon/rectum (n = 24, 12%). Most presented with early-stage disease (n = 124, 60%), with a median IPI score of 1. All patients received chemotherapy. Of 182 treated with CHOP/EPOCH, 36 (20%) were treated in the pre-rituximab era while 146 (80%) received rituximab. 66 patients (32%) were treated with RT, 89% as part of first line CMT. 50 cases (76%) received consolidative RT, while 10 (15%) targeted residual gross disease and 4 (6%) targeted distant sites. Median dose and fractionation were 36Gy (IQR 30.6-39.6) in 18 fractions (IQR 17-22). Over half (n = 132, 64%) developed grade 3+ acute chemotherapy AEs, and the most common were anemia (n = 64), febrile neutropenia (n = 40), and neutropenia (n = 20). Grade 3+ late chemotherapy AEs occurred in 14 patients (7%). Acute grade 3+ radiation AEs were uncommon (n = 2, 3%; colitis, emesis). No grade 3+ late radiation AEs were noted. Median follow-up was 46 months (IQR 16-97). 169 (81.6%) had a complete response (CR), with 154 (91%) after first line chemotherapy, 9 (5%) after second line, and 6 (4%) after RT. CR was defined by PET (62%), endoscopy (22%), CT (9%), or other methods (7%). The 5-year progression-free survival for those treated with one line of chemotherapy with or without RT was 95%. Median overall survival (OS) was not reached. Improved OS was associated with early-stage disease (p = 0.003), low IPI (p = 0.001), fewer chemotherapy lines (p<0.001), and CR (p<0.001). OS did not differ by gender, age, immunophenotype, GI site, SUVmax, or RT. Patients with early stage DLBCL treated with RT in the post-rituximab era received fewer chemotherapy cycles compared to those treated without RT (p = 0.02; median of 4 (IQR 3-6) vs 6 cycles (IQR 4-6)), with no OS difference.

CONCLUSION

GI DLBCL patients have favorable outcomes after CMT with minimal late toxicity. CMT with RT to the GI tract is well tolerated with no OS difference compared to chemotherapy alone, and may mitigate risks from additional chemotherapy cycles for selected early-stage patients.

Gender and the Receipt of the Association of Residents in Radiation Oncology (ARRO) Educator of the Year Award

PURPOSE/OBJECTIVE(S)

Despite an increase in female physicians in recent years, a gender disparity remains in the field of radiation oncology. We hypothesized that there may be a gender disparity in the receipt of ARRO educator awards.

MATERIALS/METHODS

Using a database provided by the American Society for Radiation Oncology (ASTRO), annual award recipients were identified from 2010-2022. Data on Academic Institution, Year of Award, and Repeat Awardee Status were obtained through the ASTRO database. Publicly available websites were accessed to obtain data regarding gender, years post residency graduation, percent female/male faculty, size of residency program, and program director designation. H- indices were obtained from Scopus and used as a marker of academic productivity. Basic summary statistics, stratified by gender, were calculated for award year, years since graduation, percent of male faculty, and program size. A one-sample Z-test for proportions was utilized to assess if the proportion of female ARRO award winners each year from 2010 to 2022 was significantly less than the population average, defined as the proportion of female radiation oncology faculty members in the nominating universities that year. Secondary analyses used univariable binary logistic regression to identify any global associations between gender, year since gradation, or program size.

RESULTS

The lowest proportion of female awardees occurred in 2013 (8 [14.3%] females vs. 48 [85.7%] males) and the greatest proportion of female awardees occurred in 2022 (19 [30.6%] females vs. 43 [69.4%] males). As compared to the proportion of female faculty members in nominating programs for that respective year, there were significantly fewer female awardees in the years of 2010 (18% female awardees vs. 32% female faculty members, p = 0.02) and 2013 (14% female awardees vs. 31% female faculty members, p = 0.01). There was a statistically significant rise in female awardees over the study period (p<0.01). On logistic regression analysis, large program size (10+ residents) (odds ratio [OR]: 6.86, 95% confidence interval [CI]: 2.71-23.1, p<0.001) and medium program size (5-9 residents) (OR: 4.05, 95% CI: 1.60-13.7, p<0.001) were associated with a greater proportion of female awardees as compared to small program size (1-4 residents). There was no association between awardee gender and years since graduation.

CONCLUSION

A gender disparity is present in the receipt of ARRO Educator Awards. At an institutional level, residency Chiefs, Program Directors, and Chairs should work to ensure that a diverse slate of faculty are considered annually for the ARRO Educator Award with self-assessment of awardees over time to ensure demographic representation and inclusion. Efforts should also be made to recognize biases in resident evaluations of faculty with continued education about inherent biases.

Ultra Low-Dose Radiation for Extranodal Marginal Zone Lymphoma of the Lung

PURPOSE/OBJECTIVE(S)

Definitive radiation treatment (RT) for extranodal marginal zone lymphoma (ENMZL) of mucosal associated lymphoid tissue historically involves treatment to 24-30 Gy. There is increasing data supporting the use of ultra-low dose RT as part of a response-adapted approach in the treatment of orbital and gastric ENMZL. With this approach, patients receive initial treatment with 4 Gy, and additional RT is considered for those with persistent or locally progressive disease. However limited data to date assesses the efficacy of 4 Gy in the management of ENMZL of the lung.

MATERIALS/METHODS

We performed an IRB-approved retrospective review of 17 patients with ENMZL of the lung treated with 4 Gy between 7/2015 and 12/2022 with response assessed after RT. Clinical/treatment characteristics, response, and toxicity were extracted from medical records. Statistics were performed using Mann-Whitney U and Fisher's Exact Test.

RESULTS

Eight patients (47%) were female, 15 (88%) white, and 1 (6%) Hispanic. Median age at RT was 66 (interquartile range (IQR) 59-77). All had disease limited to the lung at diagnosis and 15 had stage IE disease. Four patients (24%) were diagnosed incidentally on screening/surveillance imaging in the absence of symptoms. Sixteen patients received 4 Gy in 2 fractions, while one patient received a single fraction of 4 Gy. Median SUVmax prior to RT was 4.5 (IQR 3.2-7.2). Median planning target volume (PTV) was 74 cc (IQR 47-130cc). Six patients (35%) had respiratory symptoms prior to RT, which improved or resolved in 3 (50%). A larger PTV was associated with improvement in symptoms following RT with a median PTV of 266 cc (IQR 171-402) in those who experienced improvement vs. 64 cc (IQR 42-100) in those who did not (p = 0.032). One patient experienced toxicity following RT with pleuritic chest pain, which resolved with corticosteroids. At a median follow-up of 15 months following RT (IQR 7-43 months), the overall response rate (ORR) was 100% (CR, n = 15; PR, n = 2). Fourteen patients had follow-up PET/CT, of whom 13 had a complete metabolic response (CMR) at a median of 3 months following RT (IQR 3-5 months). Two additional patients had a complete response (CR) on CT while one had a partial response on CT. Achieving a CR was not associated with SUV prior to RT (p = 0.50) or PTV size (p = 0.62). In patients with stage IE disease, the ORR rate was 100% and there have been no distant failures to date. Fifteen of 17 patients were alive at last follow-up; two passed away of unrelated causes (one from Alzheimer's disease and one from recurrent squamous cell carcinoma).

CONCLUSION

Ultra-low dose radiation of 4 Gy is associated with excellent local control in the management of ENMZL of the lung and is very well tolerated. Four Gy was effective for local control and symptom palliation even for larger tumors and is an effective initial therapy as part of a response-adapted approach even in limited stage patients.

Enhancement Patterns of Metastatic Intrahepatic Cholangiocarcinoma and Outcomes after Chemotherapy and Radiation

PURPOSE/OBJECTIVE(S)

Patients with metastatic intrahepatic cholangiocarcinoma (M1-iCCA) have a poor prognosis with a 5-year survival rate of less than 20%. Definitive doses of radiation therapy (RT) after upfront chemotherapy (chemo/RT) in this patient population have shown to prolong survival by reducing the risk of tumor-related liver failure compared to chemotherapy alone. Our group has also identified a baseline radiographic feature, the arterial enhancement pattern, which has pathological and prognostic associations for iCCA. We tested the hypothesis that baseline arterial enhancement is independently associated with survival outcomes for patients who receive chemo/RT or chemo alone.

MATERIALS/METHODS

Patients with M1-iCCA from 2010 to 2021 were included in this retrospective study. Patients were grouped into those who underwent chemo alone and those who underwent chemo/RT. The inclusion criteria included confirmed diagnosis of M1-iCCA, availability of baseline multi-phasic computed tomography (CT), and follow-up for at least six months or until death. Tumor arterial enhancement patterns were categorized as previously described into hypovascular or hypervascular, where the tumors that were hypervascular had either peripheral enhancement or central enhancement. Mean tumor density in Hounsfield units was recorded for each patient. Survival was estimated using the Kaplan Meier method, and Cox proportional models were used to adjust for prognostic variables.

RESULTS

A total of 281 patients with iCCA were identified and 229 had evaluable CT scans. Demographic and baseline characteristics of patient groups are shown in the Table. On univariate analysis, patient age, ECOG performance status (PS) at diagnosis, treatment type, and arterial enhancement patterns associated with overall survival (OS). On multivariable analysis, the arterial enhancement pattern independently associated with OS after accounting for covariates. Patients with hypervascular tumors had prolonged OS compared to those with hypovascular tumors (HR = 0.72, [0.54 - 0.96], p = 0.02). Prolonged OS was also observed in the chemo/RT group compared to the chemo alone group (HR = 0.37, [0.25-0.54], p< 0.0001).

CONCLUSION

Baseline enhancement patterns of M1-iCCA were prognostic in the contexts of chemo alone and chemo/RT. This imaging-based biomarker may improve the ability to stratify patients for therapeutic management.