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e20590 Background: There are no blood-based biomarkers for survival prediction in inoperable stage III NSCLC patients. We propose a method for calculation of novel area under curve (AUC) biomarkers of the dynamic change of multiple leukocyte subpopulations before, during, and after thoracic irradiation (TRT), chemoradiotherapy (CRT), and chemo-radio-immunotherapy (CRT-ICI) in this patient cohort. The extracted biomarkers identify patients with early progression after TRT. Methods: 20 patients (17 male, 3 female), at median age of 65.5 years (range 34 to 79) were enrolled in the study. The median follow-up time was 60 weeks. Eleven patients suffered from adenocarcinoma, 8 squamous cell carcinoma, and 1 undifferentiated NSCLC. They received TRT (2/20, 10%), CRT (11/20, 55%), or CRT-ICI (7/20, 35%). One patient (1/20, 5%) withdrew consent and was excluded from analysis. Primary endpoints were progression free survival (PFS) at 6 and 12 months. Patient blood was analyzed via flow cytometry for 7 circulating leukocyte populations at baseline, twice during radiotherapy, at the end of radiotherapy (RTend), and 10, 20, 35, 48, and 60 weeks after enrollment. We analyzed CD3+ total T cells, CD4+ T cells, CD8+ T cells, CD19+/CD20+ B cells, CD3-CD56+ NK cells, CD56 bright NK cells, and CD56 dim NK cells. Here, we report on CD4+ and CD8+ T cells. The AUC from RTend to zenith of absolute cell counts provided aggregate measures for the time-course data. We performed hierarchical clustering and cluster characterization. Relevant features were selected by stepwise drop-out. Results: Clustering of the AUC between RTend and zenith for CD4+ T cells and CD8+ T cells delineated two prognostic groups. The favorable group was characterized by higher AUC values for CD4+ and CD8+ T cells compared to the unfavorable group. All patients (9/9, 100%) in the favorable group versus 36.4% (4/11) patients in the unfavorable group were progression-free at 6 months (Fisher´s exact test, two-tailed: p-value = 0.00472). This effect was observed as a trend with PFS at 12 months. Here 66.6% (6/9) of patients had PFS at 12 months in the favorable group versus 27.3% (3/11) in the unfavorable group (Fisher´s exact test, two-tailed: p-value = 0.175). There is a directly proportional relationship of the reported AUC values to PFS at 6 months and 12 months. Conclusions: Patients who responded with T cell expansion after immunogenic cell death by TRT, CRT, or CRT-ICI had significantly longer PFS compared to those without increase. Longitudinal monitoring of CD4+ and CD8+ T cells and the AUC from RTend to zenith is a promising biomarker for detecting early progression in the present study which is the subject of validation in an ongoing prospective study (PRECISION, NCT05027165).

e20578 Background: To investigate the impact of treatment patterns in inoperable stage III NSCLC following concurrent chemoradiotherapy with or without immune checkpoint inhibition (cCRT±ICI). Methods: Patients were stratified by treatment year and divided into three subgroups: A (2011–2014), B (2015–2017) and C (2018–2020). Patient- and treatment-related characteristics regarding to PFS and OS were analyzed. Survival parameters were calculated from the last day of thoracic radiotherapy (TRT). Results: 136 consecutive enrolled patients were included. Median follow-up (FU) was 35.7 months; median age was 66.9 years. All patients completed TRT to a total dose ≥60.0 Gy; Median radiotherapy planning target volume (PTV) was 700 cc (range: 172.5–2293.2). Thirty-six (26%) patients received ICI. Median PFS in subgroups A, B and C was 8.0, 8.2 and 26.3 months (p = 0.007). Median OS was 19.9 months, 23.4 months and not reached in subgroups A, B and C (p < 0.05). In subgroup C, median PFS was 14.2 vs. 26.3 months in patients treated with and without ICI. On multivariate analysis for the entire cohort, PTV > 700cc was a negative prognosticator of PFS (HR: 1.522; p = 0.042) and OS (HR: 2.671; p = 0.001); ICI was a predictor of improved PFS (HR: 0.571; p = 0.071) and longer OS (HR: 0.401; p = 0.062). In the Non-ICI cohort, multivariate analyses revealed PTV > 700cc (HR: 1.630; p = 0.047) and SUVmax > 13.75 (HR: 1.859; p = 0.012) were predictors of reduced PFS; PTV > 700cc (HR: 1.958; p = 0.017), SUVmax > 13.75 (HR: 2.405; p = 0.002) and total lung V20 > 30 (HR: 3.357; p < 0.05) were predictors of longer OS. Conclusions: Regardless of ICI, patients receiving multimodal therapy after 2018 demonstrated improved survival compared to patients treated earlier. Both PTV > 700cc and ICI were predictive for PFS and OS in the entire cohort.

e20589 Background: Durvalumab maintenance treatment after completion of concurrent chemoradiotherapy (CRT) in patients with inoperable stage III NSCLC is the international standard. In this propensity-matched analysis, we prospectively evaluated the role of concurrent/sequential versus sequential immune checkpoint inhibition. Methods: Between 10/1/2016 and 12/31/2020, 39 NSCLC patients in stage IIIA/B/C were analyzed. 11 (28%) patients received concurrent/sequential PD-1 inhibition (nivolumab) and 28 (72%) patients received sequential PD-L1 inhibition (durvalumab) up to one year after the end of CRT. A 1:2 propensity score matching (PSM) using age, gender, T category and histology was performed to reduce selection bias and address for confounding factors (n = 33, 11 patients receiving nivolumab (SIM-cohort), 22 patients receiving durvalumab (SEQ-cohort). Treatment-related adverse events were assessed weekly during the CRT and at 6 weeks, 3,6,9, and 12 months after the end of CRT. Results: The median follow-up time of the overall cohort, SIM-I cohort, and SEQ-I cohort was 27.6, 33.3, and 26.5 months after CRT, respectively. For the entire cohort median survival (OS) was not reached; median progression-free survival (PFS) achieved 26.3 months. In the SIM-cohort, median PFS was 22.8 months and median OS was not reached. In the SEQ-cohort, neither median PFS nor OS was reached. PFS at 12/24 months was 82/44% in the SIM-cohort and 57/57% in the SEQ-cohort (p = 0.714), respectively. In the SIM-cohort, 18.2% of patients showed grade III pneumonitis; in the SEQ-cohort 13.6% (p = 0.735). Grade 4 and 5 toxicities were not observed. Conclusions: Both concurrent/sequential and sequential immune checkpoint inhibition shows a favorable side effect profile and promising survival in terated patients. Concurrent immunotherapy did not result in an improved outcome (PFS, OS) compared to sequential approach. However, our propensity-matched analysis found that concurrent immunotherapy was associated with a non-significant moderate increase in grade III pneumonitis.

e20570 Background: We compared pattern of failure in patients treated with chemoradiotherapy (CRT) with concurrent and/or sequential Programmed Cell Death 1 (PD-1) or Ligand 1 (PD-L1) immune checkpoint inhibition (IO, immuno-oncology therapy) and CRT alone for inoperable stage III NSCLC. Methods: Prospective data of thirty nine consecutive patients who completed CRT-IO with sequential durvalumab (72%, 28 patients) or concurrent and sequential nivolumab (28%, 11 patients) and a sensitive propensity score matched (PSM adjusted for patients age, gender, T- and N-status, PTV, histology) cohort of 39 patients treated with CRT alone were analyzed. First site of failure was compared between the CRT-IO and the CRT alone subgroup. Results: All patients were treated with conventionally fractionated thoracic irradiation to a total dose of at least 60Gy (range: 60-66Gy), all patients received either sequential or simultaneous chemotherapy while 95% (74 patients; CRT-IO: 38/39; CRT alone: 36/39) received two cycles of concurrent platinum-based chemotherapy. Median follow-up for the entire cohort was 33.3 (range: 1.5-102.9) months; median overall survival (OS) was 34.9 (95%CI: 10.7-59.1) months (CRT-IO: not reached; CRT alone: 24.4, p = 0.003); median progression-free survival (PFS) was 13.6 (95% CI: 10.5-6.7) months (CRT-IO: 26.3; CRT alone: 8.3; p < 0.001). At the time of evaluation 21 (53.8%) vs. 7 (17.9%) patients of the CRT-IO vs. CRT alone subgroup were progression free and alive (p = 0.003); 4 (10.3%) vs. 3 (7.7%) had brain metastases as first site of failure; 7 (17.9%) vs. 6 (15.4%) had ≤ 3 extracranial metastasis and 3 (7.7%) vs. 4 (10.3%) had multi-organ progression. Local-regional recurrence (LRR) as first site of failure was significantly less frequent in patients treated with CRT-IO vs. CRT alone, namely 3 (7.7%) vs. 12 (30.8%) patients (p = 0.001); median time to LRR was not reached vs. 15.0 (95%CI: 0.9-33.7) months. Conclusions: Pattern of failure differ significantly in patients treated with CRT-IO vs. CRT alone; CRT-IO patients are significantly less likely to develop a LRR. No differences in the prevalence of brain metastases as first site of failure could be detected.

e20559 Background: Immune cells have a broad impact on tumor initiation, growth, and progression, and many of these effects are mediated by proinflammatory cytokines. The prognostic impact of dynamic changes of inflammatory cytokines in non-operable stage III NSCLC patients treated with (chemo)-radiotherapy ± immune checkpoint inhibition is unknown. In a prospective analysis, pro-inflammatory cytokines including interleukin 2, 6, and 8 from peripheral blood samples were evaluated 5-10 days before treatment start (T1), on the last day of thoracic radiotherapy (T2), and 3 weeks after radiation (T3) for their impact on overall survival (OS) and progression-free survival (PFS). Methods: Twenty patients, 85% male, at a median age of 65.5 (range 33-77) years were prospectively enrolled in this study. Eighteen (90%) patients received platinum-based concurrent chemoradiotherapy (CRT); seven (35%) patients additional concurrent and/or sequential immune checkpoint inhibition (four patients nivolumab and three durvalumab); patients treated with nivolumab received induction chemotherapy. Thoracic irradiation (TRT) was applied in all patients with a median cumulative dose in equivalent 2Gy fractions (EQD2) of 64Gy (range: 52-65Gy). Results: Median follow-up achieved 25 (range 14-30) months, median OS was not reached and median PFS was 11.8 (95%CI 5.2-18.4) months. To analyze pre-treatment data, median values were used as cut-off for dichotomization. Higher IL6 levels (≥9.75pg/ml) before irradiation (T1) were associated with impaired OS (median 11 months vs. not reached; p < 0.001) and PFS (median 7.0 months vs. not reached; p = 0.041). Higher IL8 levels (≥4.62pg/ml) were also associated with shorter OS (median 16 months vs. not reached; p = 0.009) and PFS (median 7 months vs. not reached p = 0.040). Patients with a decline of ≥10% of IL8 level between T1 and T2 had a significantly shorter PFS (11.8 months vs. not reached; p = 0.028). Conclusions: High proinflammatory cytokine levels were significantly associated with deterioration of outcome regarding OS and PFS in patients enrolled in multimodal treatment for stage III NSCLC. A decline of ≥10% of IL8 level during TRT was associated with impaired PFS.

e20558 Background: PET-derived metabolic-tumor-volume (MTV) has shown to be an independent prognosticator in non-small cell lung cancer (NSCLC) patients treated with chemoradiotherapy (CRT). We analysed the prognostic value of residual MTV after completion of thoracic irradiation (TRT) in inoperable stage III NSCLC patients treated with CRT with and without immune check-point inhibition (ICI). Methods: Fifty-six inoperable stage III NSCLC patients (16 female, median age: 65 years) underwent 18F-FDG PET/CT at the same institution before and after completion of CRT. MTV was delineated on 18F-FDG PET/CT using a standard threshold (hepatic SUVmean + 2 x standard-deviation). Patients were divided in volumetric subgroups using median split dichotomization (residual MTV ≤4.0 ml & > 4.0 ml). Residual MTV, clinical features and ICI maintenance (RCT-IO; 21/56 (37.5%) patients) were correlated with clinical outcome (progression-free survival (PFS), local PFS (LPFS), metastasis-free survival (MFS), and overall survival (OS). Results: Median follow-up was 52.0 months. 52 (93%) patients were treated with CRT, 12 (21%) patients with CRT followed by durvalumab, and 9 (16%) patients treated with CRT plus nivolumab (concurrent and sequential). In the entire cohort, smaller residual MTV was associated with longer PFS (median 29.3 vs. 10.5 months, p = 0.015); PFS in patients treated with CRT and ICI was also significantly longer compared to the CRT-only subgroup (median 29.3 vs. 11.2 months, p = 0.010). However, residual MTV was predictive for longer PFS in CRT-only (median 33.5 vs. 8.6 months, p = 0.001), but not in the CRT-ICI patients (p = 0.909). Analogously, patients with smaller MTV had a longer LPFS (median 49.9 vs. 16.3 months, p = 0.002); CRT-ICI patients showed a significantly longer LPFS compared to CRT-only patients (median not reached vs. 16.9 months, p = 0.016). Residual MTV remained a significant prognosticator for LPFS in the CRT-only (median 49.9 vs. 10.1 months, p = 0.01), but not in CRT-ICI patients (p = 0.291). Again, smaller residual MTV remained a significant prognosticator for OS in the CRT-only subgroup (median 63.0 vs. 16.3 months, p = 0.004), but not in CRT-ICI patients (p = 0.720). Even in patients with larger residual MTV, the application of ICI significantly improved OS compared to CRT-only subgroup (median not reached vs. 22.9 months, p = 0.004). Conclusions: Smaller residual MTV is associated with superior clinical outcome in inoperable stage III NSCLC, especially in patients undergoing CRT-only. In contrast, in patients undergoing concurrent or sequential consolidation clinical outcome was independent of residual MTV. Hence, even patients with extensive residual MTV might significantly profit from ICI consolidation.

e20557 Background: The present study evaluates outcome after chemoradiotherapy (CRT) with concurrent and/or sequential Programmed Cell Death 1 (PD-1) or Ligand 1 (PD-L1) immune checkpoint inhibition (CPI) for inoperable stage III NSCLC patients depending on planning target volume (PTV). Methods: Prospective data of thirty-nine consecutive patients with inoperable stage III NSCLC who completed CRT with sequential durvalumab (72%, 28 patients) or concurrent and sequential nivolumab (28%, 11 patients) were analyzed. Different cut offs for PTV as well as PTV as a continuous variable were evaluated for association with progression-free survival (PFS) and extracranial metastasis-free survival (eMFS). Results: All patients were treated with conventionally fractionated TRT to a total dose of at least 60 Gy (range: 60-63.6Gy), 97% (27 patients) received two cycles of concurrent platinum-based chemotherapy. Median follow-up for the entire cohort was 23.2 (range: 6.0-42.6) months; median overall survival (OS) and eMFS were not reached. Median Progression-free survival (PFS) was 22.8 (95% CI: 10.3-35.2) months. Age (65 years), gender and UICC stage had no significant impact on PFS. There was no significant difference between durvalumab and nivolumab patients. Patients with PTV ≥ 900ccm had a significantly shorter PFS (11.77 vs 26.3 months, p = 0.049) and eMFS (11.7 months vs not reached, p = 0.019). Furthermore, patients with PTV ≥ 900ccm and stage IIIC disease (TNM 8th Ed.) achieved a dismal median PFS of only 3.6 months (vs. 26.3 months p < 0.001). PTV as a continuous variable showed a trend for association with PFS (p = 0.064) and was a significant negative prognosticator for eMFS (p = 0.030; HR: 4.065; 95%CI: 1.148-14.397). Conclusions: PTV has a significant impact on the PFS and eMFS after CRT combined with concurrent and/or sequential CPI in inoperable stage III NSCLC. Patients with PTV ≥ 900ccm had a significantly shorter PFS and eMFS.

e20503 Background: Acute lymphocytopenia is associated with poor survival in solid cancers treated with multimodal therapy. A prospective analysis of peripheral blood mononuclear cells (PBMCs) during multimodal treatment in inoperable stage III NSCLC patients was performed to assess a correlation of T-lymphocytes changes with 6-months progression-free survival rates (PFS6M). Methods: Twenty patients at median age of 65.5 years (range 33-77), 85% male, 55% with adenocarcinoma and 40% with squamous cell carcinoma, were prospectively enrolled in this study. Eighteen (90%) patients received platinum-based concurrent chemo-radiotherapy (cCRT); seven (35%) patients additional concurrent and/or sequential immune check-point inhibition (four patients nivolumab and three durvalumab); patients treated with nivolumab received induction chemotherapy. Thoracic irradiation (TRT) was applied in all patients with median cumulative dose in equivalent 2Gy fractions (EQD2) of 64Gy (range: 52-65Gy). Peripheral blood was collected 5-10 days before treatment begin (A1), on the last day of TRT (RTend), and during follow-up. Samples were analyzed using polychromatic flow cytometry. Results are reported for three time-points: A1, RTend, and 6 months after TRT (C3) or the last sample available before that time-point. Results: From A1 to RTend, 16 (80%) patients experienced severe T-cell (CD3+, CD3+CD4+, CD3+CD8+) depletion, including 3 (15%) patients who received two doses of concurrent nivolumab. T-lymphocyte nadir was independent of the absolute numbers of PBMCs before treatment begin. In two patients, T-cell count remained stable, and increased in two other patients. No correlation of dynamic changes from A1 to RTend with PFS6M was observed. From RTend to C3, T-lymphocytes recovered in 11 (55%) patients; in 6 (30%) T-cell count further decreased or remained at very low levels. For total CD3 T-cells, CD3+CD4+ and CD3+CD8+ subsets, progressive disease in the first six months after TRT was associated with a decrease of median values (P = 0.03 for total CD3+ and CD3+CD4+, P = 0.08 for CD3+CD8+ T-cells). In contrast, an increase of all medians was associated with PFS6M (P = 0.007 for total CD3+, P = 0.002 for CD3+CD4+, P = 0.06 for CD3+CD8+ T-cells). Conclusions: There is a significant difference between patients with regards to T-lymphocytes recovery after the end of TRT, which is predictive for PFS6M, with poor median recovery observed in patients with early progress.

Purpose In patients with newly diagnosed glioblastoma that harbors a nonmethylated O6-methylguanine–DNA methyltransferase promotor, standard temozolomide (TMZ) has, at best, limited efficacy. The GLARIUS trial thus explored bevacizumab plus irinotecan (BEV+IRI) as an alternative to TMZ. Patients and Methods In this phase II, unblinded trial 182 patients in 22 centers were randomly assigned 2:1 to BEV (10 mg/kg every 2 weeks) during radiotherapy (RT) followed by maintenance BEV (10 mg/kg every 2 weeks) plus IRI(125 mg/m2 every 2 weeks) or to daily TMZ (75 mg/m2) during RT followed by six courses of TMZ (150-200 mg/m2/d for 5 days every 4 weeks). The primary end point was the progression-free survival rate after 6 months (PFS-6). Results In the modified intention-to-treat (ITT) population, PFS-6 was increased from 42.6% with TMZ (95% CI, 29.4% to 55.8%) to 79.3% with BEV+IRI (95% CI, 71.9% to 86.7%; P Conclusion BEV+IRI resulted in a superior PFS-6 rate and median PFS compared with TMZ. However, BEV+IRI did not improve OS, potentially because of the high crossover rate. BEV+IRI did not alter QOL compared with TMZ.

2517 Background: Previously, we identified a prognostic 4-miRNA signature (built from let-7a-5p, let-7b-5p, miR-125a-5p and miR-615-5p) in glioblastoma patients treated according to the EORTC26981/22981-NCIC CE3 protocol. We present results of a novel external validation and will report on a completed prospective study on blood plasma samples of glioblastoma patients prior to chemoradiotherapy (CRT). Methods: The external validation cohort (n = 103) contained IDH1/2 wildtype tumors with known MGMT promoter methylation from the LMU-Munich (n = 37), the University Hospital Düsseldorf (n = 33) and TCGA (n = 33). Risk groups from the combination of miRNA signature with MGMT promoter methylation were analyzed for overall survival (OS) and prognostic performance using C-index. Within the prospective study (n = 52), blood samples were taken prior to RT, on d42 and d84 (22 cases analyzed up to now). Risk scores were obtained from signature miRNA expression levels in resection or biopsy specimen (retrospective, endpoint OS) and blood plasma (prospective, PFS). Results: The 4-miRNA signature was independent of sex and MGMT promoter methylation (p > 0.1) and defined high-risk (n = 47, med. OS: 16.4months) and low-risk (n = 56, med. OS: 26.9months) patients (HR: 2.08, 95%CI: 1.25-3.46, p = 0.004). Patients with methylated (med. OS: 23.7months, n = 54) compared to non-methylated MGMT promoter (med. OS: 16.8months, n = 49) had superior OS (p = 0.007, HR: 0.48, 95%-CI: 0.28-0.82). Combining the 4-miRNA signature and MGMT promoter methylation resulted in the signature-low-risk/ MGMT-promoter-methylated (med. OS: 37.4months), signature-low-risk/ MGMT-promoter-unmethylated (med. OS: 24.7months), signature-high-risk/ MGMT-promoter-methylated (med. OS: 16.4 months) and signature-high-risk/ MGMT-unmethylated groups (med. OS: 14.3months, Log-rank p = 0.002) with superior prediction performance. Conclusions: We confirmed the 4-miRNA signature as an independent prognosticator in IDH-wildtype glioblastoma while combination with MGMT promoter methylation outperformed other established prognostic factors. Our hypothesis is, that blood plasma samples will allow the risk stratification of glioblastoma patients before CRT. Phenotypic alterations driving its prognostic value remain to be determined and will allow for 1) risk stratified trials, 2) pathway analysis and targeting and 3) testing in healthy subjects to elucidate its screening potential.

e21011 Background: Lymphocytopenia is associated with deterioration of patient survival in solid cancers treated with concurrent chemo/radiotherapy (cCRT). A prospective analysis of peripheral blood mononuclear cells during cCRT in inoperable stage III NSCLC patients was performed to determine dynamic changes of individual lymphocyte subsets. Methods: Twenty-one patients were prospectively enrolled in this study. Eighteen patients received platinum-based cCRT, seven of them received, additionally, concurrent and/or sequential immune checkpoint-inhibition (ICI). Thoracic irradiation (TRT) was delivered with median total dose of 62Gy (31 daily fractions of 2Gy) in all patients. Peripheral blood was collected 5-10 days before treatment (A1), three weeks after start of cCRT (A3), on the last day of TRT (RTend) and during follow-up. Samples were analyzed using polychromatic flow cytometry. Results are reported for time-points A1, A3 and RTend. Results: Sixteen patients met final analysis criteria, 50% of them received concurrent and/or sequential ICI. All patients developed severe lymphocytopenia; in 81% of them lymphocyte nadir was documented at A3. Lymphocyte subsets, B cells, T cells (CD4, CD8), regulatory T cells, and NK cells, decreased with medians between 99.9% and 59%. Lymphocyte nadir was independent of the absolute numbers of immune cells that a patient had before start of cCRT or whether additional ICI was applied. From A3 to RTend, all lymphocyte subsets started to recover in patients treated with cCRT alone, while they remained low in patients who received additional ICI. The ratios of CD4/CD8 and CD8/Treg cells did not change during treatment (A1 to RTend) and was not different between the patients treated with or without ICI. However, the fraction of PD-1 cells among CD8 T-cells decreased in patients treated with ICI and remained low until RTend (range 0.55%-13.8%). In contrast, in 50% of patients treated with cCRT alone, PD-1 T-cell among CD8 T-cells increased and remained high (range 6.8%-46.3%) until RTend. Conclusions: Delayed recovery of lymphocyte subsets in peripheral blood was observed in patients treated with cCRT combined with concurrent or sequential ICI. A decrease of PD-1 T-cells among CD8 T-cells was described exclusively in patients treated with additional ICI.

9049 Background: The metabolic tumor volume (MTV) is a functional and volumetric PET/CT parameter that has been investigated in recent years with respect to its predictive and prognostic value in different tumor entities. In this study, we investigated the role of residual MTV after completion of thoracic irradiation in inoperable stage III non-small cell lung cancer (NSCLC). Methods: We analyzed retrospective and prospective data of 56 patients with inoperable stage III NSCLC treated with chemoradiotherapy (CRT) and chemoradioimmunotherapy (CRT-IO). All patients received an 18F-FDG-PET/CT 3 to max. 6 months after completion of thoracic irradiation. The measurement of the residual MTV of the primary tumor was performed by calculating the SUVmean of the liver + 2SD as threshold. The patients were divided into the following groups: residual-MTV < 1ml; residual-MTV 1-25ml and residual-MTV > 26ml. Survival, local recurrence, and distant metastasis rates were calculated using the Kaplan-Meier method from the last day of thoracic irradiation. Results: The median follow-up was 45 months (range 16-74) in the CRT group and 16 months in the CRT-IO group (range13-19). Twenty-two (39%) patients had a residual MTV < 1ml (1st group), 19 (34%) a residual MTV between 1-25ml (2nd group) and 15 (27%) a residual MTV > 25ml (3rd group) after completion of thoracic irradiation. Median overall survival was 61, 20 and 12 months (p = 0.006) in the 1st, 2nd and 3rd groups, respectively. 12-month survival was 86%, 50% and 33% after CRT vs. 88%, 71% and 50% after CRT-IO in the 1st, 2nd and 3rd groups, respectively. The median time to in-field recurrence in the 1st, 2nd and 3rd groups was 51, 20 and 15 months (p = 0.011). The prognostic value of the residual MTV on OS was confirmed exclusively in the CRT patient cohort (p = 0.04), but not in the CRT-IO patient cohort (p = 0.174). Residual MTV demonstrated no influence on the local recurrence rate in the CRT-IO patient cohort, but only in patients treated with CRT (p = 0.007). Conclusions: Patients with inoperable stage III NSCLC in whom the residual MTV was < 1ml after completion of thoracic irradiation showed significantly better survival than patients with a residual MTV of 1-25ml and MTV > 25ml. The subgroup analysis confirmed the prognostic value of residual MTV only in patients who received chemoradiotherapy without consolidation immunotherapy.

2057 Background: Local recurrence after surgery and radio(chemo)therapy remains a major obstacle in curative treatment of patients with HGG. Eradication of radioresistant glioma subpopulations (hypoxic- and stem cell like cells) together with formation of an antiangiogenic and immuno-permissive glioma niche are among beneficial radiobiological effects recently attributed to carbon ion irradiation in preclinical models. The impact of this novel therapy in management of rHGG patients remains elusive. Methods: 197 patients with rHGG (grade III: 71, IV: 126) received RiCi between Nov 2009 and Feb 2018 at HIT with a median dose of 42GyRBE in 14 fractions. In DKTK-ROG multicenter cohort n:565 rHGG patients (grade III: 63, IV: 479) underwent RiP between 1997-2016 with a median dose of 36 Gy in 14 fractions. Median follow up was 34.2 months (M) for RiCi and 7.1 M for RiP (DKTK) cohort. All three prognostic scores validated in DKTK-ROG cohort were evaluated and re-irradiation risk score (RRRS) considering initial grade, Karnofsky Performance Score and age at re-irradiation was utilized for stratification and matched comparisons. Results: Median PFS was 5.08 [4.26-5.87] M (grade III: 6.79, grade IV: 3.64) after RiCi, data was not available for RiP. Median OS was 10.52 [9.28-12.66] M (grade III: 28.2, grade IV: 8.53) after RiCi compared to 7.93 [7.15-8.79] M (grade III: 10.89, grade IV: 7.93) after RiP. Among the three prognostic scores evaluated, RRRS most robustly correlated with OS. RiCi was associated with HR of 0.52 ([0.49-0.72], p = 0.0000002), and HR 0.66 ([0.51-0.85], p = 0.001) for RRRS matched analysis. Conclusions: Carbon ions demonstrated activity in rHGG. This effect is most prominent in grade III while grade IV patients may further benefit from innovative multimodal strategies. Based on these encouraging results prospective randomized trials utilizing RRRS for stratification are recommended.

6050 Background: CTGF plays a central role in tissue remodeling and has emerged as an attractive novel therapeutic target. We sought to investigate the impact of CTGF methylation status (CTGF-M) in predicting outcome of HNSCC patients undergoing RCHT. Methods: CTGF-M was discovered by applying Illumina 450K/850K arrays to DNA extracted from FFPE material of patients homogeneously treated with surgery followed by adjuvant cisplatin-based RCHT in frame of the DKTK-ROG multicenter retrospective trial (n = 194, training cohort). Methylation probes correlating with overall survival (OS) and progression were identified using random forest. Validation was done in 4 cohorts including DKTK-ROG definitive RCHT (n = 110) and 3 RCHT cohorts from Heidelberg, Dresden and Munich (n = 222). CTGF-M and RNAseq data from The Cancer Genome Atlas (TCGA) (n = 206) were analyzed to identify differentially expressed genes (DEG) as a function of CTGF-M. Results: Increased methylation of 2 probes (mapping to CTGF 3’UTR and gene body) was associated with significantly improved OS in the training cohort (HR = 0.51, p = 0.044) and the validation cohort (HR = 0.67, p = 0.016), in multivariate cox regressions adjusting for HPV status, age, T and N stages, location and treatment (adjuvant vs definitive RCHT). In the TCGA, probes’ methylation was significantly inversely correlated with CTGF gene expression (r = -0.18 and -0.51, p < 0.05). 1843 DEGs were found at FDR < 0.05 as a function of CTGF-M. Pathways mapping to tissue remodeling were significantly enriched for among downregulated genes in CTGF hypermethylated tumors. Increased CTGF methylation was inversely correlated with the mesenchymal subtype mRNA gene signature (r = -0.21, p = 0.0026) and correlated with the atypical subtype (r = 0.32, p = 0.000002). Conclusions: Implementation of CTGF-M in routine diagnostic is feasible and correlates well with CTGF gene-expression levels and activation of tissue remodeling pathways. Therefore, CTGF-M might be instructive for stratifying HNSCC patients for CTGF targeting therapies. CTGF emerges as a promising prognostic marker independently of HPV status.

6019Background: Human Papilloma Virus (HPV)-driven head and neck cancer (HNSCC) is associated with good prognosis. The prognostic value of HPV-DNA and p16 IHC was recently reported by this consorti...

6047Background: Mutational load and immune expression signatures have previously been established as efficacy biomarkers in immune checkpoint inhibitor (ICI) trials. It is important to know the val...

8510Background: The feasibility of combined chemo-radiotherapy (chemo-RT) and concurrent PD-1 inhibition is of high scientific interest and has shown promising results in pre-clinical models. So fa...

6028Background: We performed an open label phase 2 trial and investigated the efficacy and toxicity of additional cetuximab during and after adjuvant radiochemotherapy (RCT) in head and neck cancer...

Purpose Concurrent chemoradiotherapy with or without surgery are options for stage IIIA(N2) non–small-cell lung cancer. Our previous phase II study had shown the efficacy of induction chemotherapy followed by chemoradiotherapy and surgery in patients with IIIA(N2) disease and with selected IIIB disease. Here, we compared surgery with definitive chemoradiotherapy in resectable stage III disease after induction. Patients and Methods Patients with pathologically proven IIIA(N2) and selected patients with IIIB disease that had medical/functional operability received induction chemotherapy, which consisted of three cycles of cisplatin 50 mg/m2 on days 1 and 8 and paclitaxel 175 mg/m2 on day 1 every 21 days, as well as concurrent chemoradiotherapy to 45 Gy given as 1.5 Gy twice daily, concurrent cisplatin 50 mg/m2 on days 2 and 9, and concurrent vinorelbine 20 mg/m2 on days 2 and 9. Those patients whose tumors were reevaluated and deemed resectable in the last week of radiotherapy were randomly assigned to receive a chemoradiotherapy boost that was risk adapted to between 65 and 71 Gy in arm A or to undergo surgery (arm B). The primary end point was overall survival (OS). Results After 246 of 500 planned patients were enrolled, the trial was closed after the second scheduled interim analysis because of slow accrual and the end of funding, which left the study underpowered relative to its primary study end point. Seventy-five patients had stage IIIA disease and 171 had stage IIIB disease according to the Union for International Cancer Control TNM classification, sixth edition. The median age was 59 years (range, 33 to 74 years). After induction, 161 (65.4%) of 246 patients with resectable tumors were randomly assigned; strata were tumor-node group, prophylactic cranial irradiation policy, and region. Patient characteristics were balanced between arms, in which 81 were assigned to surgery and 80 were assigned to a chemoradiotherapy boost. In arm B, 81% underwent R0 resection. With a median follow-up after random assignment of 78 months, 5-year OS and progression-free survival (PFS) did not differ between arms. Results were OS rates of 44% for arm B and 40% for arm A (log-rank P = .34) and PFS rates of 32% for arm B and 35% for arm A (log-rank P = .75). OS at 5 years was 34.1% (95% CI, 27.6% to 40.8%) in all 246 patients, and 216 patients (87.8%) received definitive local treatment. Conclusion The 5-year OS and PFS rates in randomly assigned patients with resectable stage III non–small-cell lung cancer were excellent with both treatments. Both are acceptable strategies for this good-prognosis group.

2042^ Background: There is a need for more effective therapies in newly diagnosed glioblastoma (GBM) patients with an MGMT-non-methylated tumor. The GLARIUS trial explored the efficacy of bevacizum...

4081 Background: Patients (pts) with LAEC have a poor prognosis; new therapies are required. A study showed the addition of Cet to RCT to be safe and effective for resectable EC [Ruhstaller et al, ...

1121 Background: In 2010, we reported data on local control and early toxicity for the TARGIT-A trial of intraoperative radiotherapy after lumpectomy for early breast cancer. The updated results and first analysis of survival of the whole cohort (n = 3,451) were presented at San Antonio Breast Cancer Symposium in December 2012. We analysed the German cohort of patients, which was supposed to be more homogeneous (prepathology IORT only, homogeneous treatment in EBRT arm) and lower risk (older, smaller tumors, larger margin) than the international cohort of patients due to legal restrictions for radiotherapy studies in Germany. Methods: TARGIT-A was a randomised trial in patients >=50 years with invasive ductal carcinoma (70y 12%. Tumour sizes were 0-1cm 35%, 1.1-2cm 55% and >2cm 11%. Grade I 29%, II 59%, III 12% and nodes negative 81%, 1-3 nodes 16%, >3 nodes 3%. At 5-years, the absolute number of events in TARGIT vs. EBRT were as follows: Primary outcome: IBR 4 vs. 1, Exploratory outcome: All recurrences (breast +axilla+contralateral+distant recurrence) 11 vs. 7, Secondary outcome: All deaths 6 vs. 12, Breast Cancer deaths 3 vs. 5, Non-Breast Cancer deaths 3 vs. 7. Conclusions: Patients in the TARGIT-A trial have excellent 5 year outcomes (local control > 97%, overall survival >= 94%) in both arms of the trial. Clinical trial information: protocol 99PRT/47.

TPS7617 Background: Patients with non-small cell lung cancer (NSCLC) who respond to treatment with epidermal growth factor receptor tyrosine kinase inhibitors (EGFR TKIs) seem to be at increased risk of central nervous system relapse, and may benefit from prophylactic cranial irradiation (PCI) more than other NSCLC patients. Methods: This study investigates the safety and efficacy of combining PCI with EGFR TKIs in stage IV NSCLC. Patients with stage IV NSCLC, no evidence of brain metastases, and an indication for first or later line therapy with an EGFR TKI will be enrolled. Those with complete response (CR), partial response (PR), or stable disease (SD) following 6 weeks of therapy and no evidence of brain metastases on MRI will be treated with PCI. Neurocognitive function, depression indices, quality of life, symptoms, and ability to function independantly will be assessed at baseline, before PCI, and at 6 week and then 3 month intervals following PCI. MRI will be repeated 6 weeks following PCI and at 3 month intervals, and serum markers of blood brain barrier permeability (neuron-specific enolase (NSE), protein S100 beta) will be assessed at all visits. Safety data will be formally reviewed after the first 10 patients. The primary endpoint for efficacy is overall survival. Secondary endpoints include progression free survival, site of progression, quality of life and neurological disability. Planed subgroup analyses based on mutation status, line of treatment with TKIs, comorbidity, precise histology and molecular biology will be carried out.

e16033 Background: The prognosis for HNC patients (pts) after surgical treatment and adjuvant chemoradiation (CRT) is unsatisfactory in case of close resection margin 2 d1-d5 + d29-33) were given concurrently to postoperative RT using an integrated boost IMRT-technique (1.8/2.0/2.2Gy QD) to a total dose of 61.6 Gy. CTX started 7 days prior CRT with a loading dose of 400 mg/m2 followed by weekly CTX (250 mg/m2) during CRT. Maintenance CTX started after completion of CRT plus CTX with 500 mg/m² every 2 weeks over a 6-month period. Results: 55 of 80 planned pts (46 male, 9 female, mean age 55.6, range 29-70 years) have finished CRT, 50 are evaluable for toxicity. Concurrent CRT plus CTX was associated with grade 3-4 (CTC 3.0) mucositis, radiation dermatitis, and skin reaction outside the radiation portals in 46%, 28%, and 14% of pts, respectively. One toxic death occurred (peritonitis at day 57). CTX was terminated in 10% of all pts (allergic reactions) after the first application. In 22% of all pts CTX was discontinued during the last 2 weeks or at the end of CRT. Of those pts embarking on maintenance therapy, 80% were still on CTX after 3 and 63% after 5 months. 48% completed 6 months maintenance therapy. Conclusions: Adjuvant CRT in combination with CTX followed by maintenance CTX is feasible with toxicity in the expected range. Compliance to maintenance CTX was satisfactory during the first 3-5 months.

5540 Purpose: Inoperable loco-regional recurrences of head and neck cancer in a previously irradiated volume (RH&N) represent a therapeutic dilemma. Chemotherapy alone has no curative potential, wh...