ESTRO 2020 Abstract Book

S532 ESTRO 2020

1 LMU University Hospital Grosshadern, Department of Radiation Oncology, Munich, Germany 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.)

that only 20-50% of patients undergo cCRT, mainly due to concerns about toxicity in elderly patients with comorbidities. We studied toxicity and early mortality in stage III NSCLC in patients who were treated at a single institution in accordance with the 2014 ESMO guidelines. Material and Methods Details of all stage III NSCLC patients who underwent radical thoracic radiation to 50 Gy or higher between 2015- 2017 at our institution, were accessed from an ethics- approved database. Patients undergoing any surgery, SABR or who had previous thorax radiotherapy were excluded. Information on patient comorbidities, tumor and treatment characteristics, the incidence and severity of early toxicity, and dates of death were collected. Results A total of 129 patients with stage III NSCLC who were discussed at the joint multidisciplinary tumor board of our institution and referring hospitals fulfilled our inclusion criteria. Of these, 49.6% underwent cCRT with platinum- doublet chemotherapy, 34.1% sequential chemo- radiotherapy (sCRT) and 16.2% radiotherapy (RT) alone. In 14% of patients initially considered suitable for cCRT, the final treatment choice was sCRT (n=14) or only RT (n=4), for reasons ranging from poor performance (50.0%), patient preference (27.8%) or a large target volume (16.7%). Radiotherapy was delivered using hybrid or full Intensity Modulated Radiotherapy / Volumetric Modulated Arc Therapy. The prescribed dose was between 60-66 Gy in 89% of patients. Patient demographics, comorbidities, tumor and treatment characteristics, toxicity, and mortality rates are summarized below [Table]. Rates of ≥grade 3 toxicity for all 129 patients were as follows: esophagitis 14.0%, radiation pneumonitis 3.1% and other toxicities 4.7%. 90-day mortality rates for the cCRT, sCRT and RT arms were 1.6, 11.4 and 19.0%, respectively. The corresponding 1-year mortality rates were 21.9, 36.4, and 47.6%. Of all 90-day deaths, 60% were attributed to co- morbidities and 40% were considered lung cancer-related. Patient deaths observed between days 91-365 post- treatment were considered secondary to disease progression in 63.3%, and to co-morbidities in another 10%.

Conclusion In patients with stage III NSCLC, the observed rates of acute toxicity of cCRT were similar to those reported in phase III trials, thereby allowing patients to be eligible for adjuvant durvalumab. High 90-day and 1-year mortality rates were observed in patients considered unsuitable for cCRT. Our findings seem to reflect the selection process that directs patients to the most appropriate treatment. More effort is required to identify key determinants of frailty in this population and to identify or develop the most suitable alternative strategies for those who are unfit for cCRT. PO-0997 Evaluation of outcome and toxicity of Durvalumab treatment after CRT in inoperable stage III NSCLC L. Käsmann 1 , J. Taugner 1 , C. Eze 1 , O. Roengvoraphoj 1 , C. Belka 1 , F. Manapov 1