ESTRO 2020 Abstract book

S578 ESTRO 2020

eligible for further evaluation. The respondents work in 87 different cities and 44% in a private medical practice, 29% in university and 22% in a general hospital. Responses of the same department were analysed for congruence. Durvalumab was implemented in clinical routine by 143 (70%) respondents. Reasons for failed implementation in clinical practice were patient ineligibility, decision of medical oncologists or absence of updated German evidence review (S3-guidelines) regarding this treatment approach. Durvalumab was generally administered according to the respondents by private oncological practices in 32%, general or university hospital in 57% and in the radiation oncology department, which delivered the CRT in 11% of cases. Importantly, according to 36% of all respondents initial PD-L1 status was present in ≤30% of all patients. 82% of respondents have treated 1-15 patients with durvalumab and 14% of respondents >15 patients. Furthermore, no respondent had applied durvalumab in less than 14 days after the completion of CRT. 65 (46%) and 49 (34%) respondents started durvalumab 14-28 days and later than 28 days after CRT, respectively. The majority of respondents (>80%) re-staged the patients with CT (thorax/upper abdomen) prior to durvalumab. Severe side effects requiring hospital admission in more than 10% of all patients were reported by only 12% of all respondents. Conclusion Durvalumab was implemented in the multimodal treatment of inoperable stage III NSCLC and administered by the absolute majority of respondents. Low testing rates of PD-L1 at initial diagnosis were observed and should be considered a major barrier to universal adoption and integration in the clinical work-flow. No respondent applies durvalumab in less than 14 days after CRT and reasons of treatment delay need to be evaluated in further studies. Durvalumab appears to be well tolerated. However, treatment-related side effects need to be considered during and after multimodal therapy. PO-0999 Deciphering the tumor microenviroment based on PD-L1 expression and CD8+ TILs density in LA-NSCLC L. Käsmann 1 , K. Gennen 1 , J. Taugner 1 , C. Eze 1 , M. Karin 1 , O. Roengvoraphoj 1 , J. Neumann 2 , A. Tufman 3 , M. Orth 1 , S. Reu 4 , C. Belka 1 , F. Manapov 1 1 LMU University Hospital Grosshadern, Department of Radiation Oncology, Munich, Germany ; 2 LMU Ludwig- Maximilians-University, Department of Pathology, Munich, Germany ; 3 LMU University Hospital Innenstadt, Department of Pneumology, Munich, Germany ; 4 University Wuerzburg, Department of Pathology, Wuerzburg, Germany Purpose or Objective The prognostic role of the tumor immune microenvironment in multimodal treatment for locally advanced non-small cell lung cancer (LA-NSCLC) is unclear. Increasing evidence suggests treatment benefit depending on tumor cell PD-L1 expression. The purpose of this retrospective single-center study was to investigate the prognostic value of PD-L1 expression on tumor cells in combination with CD8+ tumor stroma-infiltrating lymphocytes (TILs) density in inoperable LA-NSCLC treated with concurrent chemoradiotherapy (CRT). Material and Methods We collected retrospectively clinical characteristics and initial tumor biopsy samples of 31 inoperable LA-NSCLC patients treated with concurrent CRT. PD-L1 expression on tumor cells (0% versus ≥1%), CD8+ TILs density (0-40% vs. 41-100%) and tumor immune microenvironment (TIME) classification (stratification into four subgroups: PD- L1neg/CD8low, PD-L1neg/CD8high, PD-L1pos/CD8low versus PD-L1pos/CD8high) were evaluated for potential prognostic value in terms of local control, progression-free

Purpose or Objective PD-L1 inhibition with Durvalumab as maintenance treatment after concurrent chemoradiotherapy (CRT) has become the standard of care in inoperable stage III non- small cell lung cancer (NSCLC) based on the excellent PACIFIC trial results. The aim of this prospective single center study was to evaluate the outcome and toxicity of Durvalumab treatment after CRT. Material and Methods All patients at our cancer center treated with Durvalumab maintenance treatment after CRT for inoperable stage III NSCLC were prospectively included in this study. Clinical characteristics, toxicity and outcome were evaluated. Toxicity was collected using the Common Terminology Criteria for Adverse Events version 5 before and during treatment. Re-staging after CRT and before the start of durvalumab consisted of a CT scan (thorax/upper abdomen). 18F-FDG-PET-CT was performed 3 months and CT 6 months after start of maintenance treatment. Results Data of 16 patients treated with durvalumab after CRT/RT were evaluated. Three patients (19%) were female and 13 (68%) male, median age at treatment start was 64 years. 10 (53%) patients had T4 or T3 tumors, four (25%) patients had N3 and 9 (56%) N2 disease. 15 Patients had CRT with a medium radiation dose of 63.20 Gy and were treated with two concurrent cycles of platin-based chemotherapy. One patient was treated with moderate hypofractionated radiotherapy without chemotherapy. Median follow-up was 7 (range:2-16) months. All patients were alive at the time of evaluation. Four (25%) patients have developed oligoprogression. Metastastic sites were bone, brain, adrenal gland and distant lymph nodes. Two patients received second-line chemotherapy after distant failure. Another two received stereotactic body radiotherapy for all metastatic sites and continued on durvalumab. Common toxicity during durvalumab was dermatitis (I-II° CTCAE) which occurred earliest after 2 cycles in 10 (65%) patients and pneumonitis II° CTCAE in 2 (13%) and III° CTCAE in 2 (13%) patient between 2-7 months after completion of CRT. In total, 3 (19%) patients discontinued durvalumab treatment after a median of 4 months due to distant progression or unacceptable toxicity. Conclusion Durvalumab was well tolerated with reversible acute toxicity. 25% of patients develop oligoprogression after a mean time of 5.5 months after the end of CRT. PO-0998 Durvalumab treatment after CRT in inoperable stage III NSCLC – a German radiation oncology survey L. Käsmann 1 , J. Taugner 1 , C. Eze 1 , O. Roengvoraphoj 1 , C. Belka 1 , F. Manapov 1 1 LMU University Hospital Grosshadern, Department of Radiation Oncology, Munich, Germany Purpose or Objective Consolidation PD-L1 inhibition with durvalumab after platin-based concurrent chemoradiotherapy (CRT) has become the standard of care in inoperable stage III non- small cell lung cancer (NSCLC) based on the PACIFIC trial results. Treatment recommendations need time for implementation in nationwide settings and require the close interaction of different medical specialities. In this nationwide survey, we questioned the distribution and clinical settings of durvalumab treatment after concurrent CRT, observed side effects of this treatment and summarize follow-up management. Material and Methods We surveyed radiation oncology institutions in Germany via an anonymous online questionnaire sent by e-mail to all members of the German Radiation Oncology Society (DEGRO e.V.) Results We received a total of 255 responses (response rate: 18%). Of which 203 (80%) were completed and returned and thus