Impact of Salvage Versus Palliative Dose Bridging Radiation Therapy on Local Control and Overall Survival in Patients with DLBCL Receiving CD19 CAR T Cell Therapy

PURPOSE/OBJECTIVE(S)

In patients with relapsed/refractory diffuse large B-cell lymphoma (DLBCL), radiation therapy (RT) can be used to "bridge" patients during the period of chimeric antigen receptor T cell (CAR T) manufacturing. Although RT has been shown to improve local control (LC) in patients who receive RT versus do not, it is unknown whether there is an optimal dose.

MATERIALS/METHODS

This was a retrospective study of patients with DLBCL who received bridging RT and CAR T cell therapy between 8/2021 and 12/2022 at a single institution (IRB #202103122). Patient, disease, and treatment characteristics were abstracted. PET/CT and laboratory data were collected at various time points. RT data including dose, planning target volume (PTV), and body volume receiving 2Gy and 4 Gy were tested for associations with LC, overall survival (OS), cytokine release syndrome (CRS) and immune effect cell-associated neurotoxicity syndrome (ICANS). Statistical tests were performed using Python libraries.

RESULTS

Twenty-two patients with DLBCL were included for analysis. The median patient age was 68 (range 35-82) and the median prior lines of failed therapies was two. All patients had successful apheresis and subsequent CAR T manufacturing. No patients died before CAR T infusion. All patients had a pre-radiation PET/CT scan that showed Deauville 5 disease. Patients with limited stage disease received salvage dose RT (EQD2∼40Gy, n = 8) while patients with advanced disease received palliative dose RT (n = 14). The median PTV volume was 1332 cm3. With a median follow-up of 156 days (IQR 63 - 252 days) from CAR T infusion, 10 patients had died and six progressed at an RT target. A higher salvage RT dose was not associated with LC at the day 30 PET or day 90 PET time points. In a Cox regression model, no independent variable, including RT dose, was significantly associated with LC or OS, but post-RT residual target SUV trended toward an association with OS (HR 6.2, 95% CI 0.9 - 471.0, p = 0.06). Post-RT LDH was associated with CRS grade (ρ = -0.39, p = 0.05). Other non-significant associative trends were noted between CRS grade and post-RT absolute lymphocyte count (ALC) (ρ = - 0.33, p = 0.09) and residual target SUV max (ρ = - 0.37, p = 0.08) and between ICANS grade and pre- to post-RT LDH change (ρ = -0.38, p = 0.06) and post-RT lymphocyte count (ρ = 0.36, p = 0.07). In an exploratory analysis of body volume receiving integral doses of 4Gy or 2Gy and pre- and post-RT ALC change, it appeared that higher integral dose did lead to larger decreases in ALC (ρ = -0.32, p = 0.15 and ρ = -0.3, p = 0.18, respectively).

CONCLUSION

In this small series of patients with r/r DLBCL treated with bridging RT prior to CAR T therapy, RT dose was not associated with LC. However, higher post-RT target residual SUV was associated with worse OS. The impact of post-RT LDH on CRS and ICANS grades should be explored further.

Controlling luminescent silicon nanoparticle emission produced by nanosecond pulsed laser ablation: role of interface defect states and crystallinity phase

In this study, we provide a systematic study on the origin of green and blue emission from luminescent silicon nanoparticles (Si-NPs) synthesized in water using a nanosecond pulsed laser ablation methodology.

The incidence and impact of comorbidity on survival and selection of initial treatment in elderly patients (pts) with head and neck cancer (HNC)

6065

Background: Comorbidity has been shown to be a determinant of survival and treatment selection in various cancers including HNC. Higher comorbidity index is associated with higher utilization of non-curative intent treatment. Methods: In this retrospective study we analyzed 182 consecutively treated HNC pts >65 years (y) old at the Dallas VAMC from January 2000 through June 2007. Comorbidity was assessed with the Charlson Comorbidity Index (CCI). Treatment was classified as curative intent versus non-curative intent. The goals were 1) to demonstrate burden of comorbidity and 2) to demonstrate the impact of comorbidity on overall survival and selection of initial treatment in elderly HNC pts. Results: Pts characteristics: 100% male; 80% white, 19.5% Black, 0.5% Hispanic; median age 72y (range 65–87); 3% stage 0, 26% stage I, 20% stage II, 18% stage III, 30% stage IV, 2% unknown; primary site - 30% oral cavity, 4% hypopharnyx, 22% oropharynx, 38% larynx, 4% other, 1% unknown; treatment - 26% radiation only, 44% surgery (S), 21% chemoradiation (CR), 9% no treatment; Median CCI -2 (range 0–11); 61% had CCI score 0–2 and 39% had CI score > 3. Median overall survival was 883 days (SE 19.31 days). Rate of curative vs. non-curative intent treatment was 80% vs. 20% respectively. Pts with CCI score 0–2 had a non-significant higher rate of curative intent treatment than pts with CCI score > 3 (83.8% vs. 74.6% p = 0.13). In multivariate analysis including CCI, age, race, alcohol use, primary site, treatment, and stage, only advanced clinical stage had significant prognostic importance (HR 1.66; 95% CI, 1.29 to 2.14; p < 0.0005). The HR for CCI was 1.11 (95% CI, .99–1.24; p = 0.08). In separate multivariate analyses of pts treated with S and pts treated with CR, CCI was not a significant predictor of survival with HR of .88 (95% CI, .69–1.11; p = 0.29) and 1.13 (95% CI, .83–1.53; p = 0.44), respectively. Conclusions: In our population of elderly HNC pts, CCI and age had no significant impact on survival or selection of curative intent treatment. Additional study is required to better define appropriate candidates for curative intent treatment in this population.

No significant financial relationships to disclose.