Abstract 412P
Background
Immune oncologic (IO) therapies remarkably changed the therapy landscape in NSCLC and pathologists are more and more facing the task to assess pathologic response following neoadjuvant immunochemotherapy for NSCLC. Therefore, we set up a multicenter study to evaluate the current practice of regression grading in Germany (Re-GraDE NSCLC).
Methods
Altogether 78 NSCLC resection specimens following neoadjuvant IO therapy were retrospectively collected from 7 high volume lung cancer centers in Germany. Case characteristics were obtained from pathology reports and electronic medical records, collected and evaluated in a central database.
Results
In pretherapeutic biopsies, 38 out of 78 patients (48.7%) were diagnosed with lung adenocarcinoma, and 34 patients (43.6%) with squamous cell carcinoma. Frequency of molecular alterations was as expected with TP53 and KRAS as most common alterations and underrepresentation of EGFR and ALK alterations. Adjuvant IO therapy showed marked response with pathological complete remission (pCR) in 47.4% of patients. The grading sytems of Junker and IASLC were used with various frequencies, but both provided robust metrics for pathologic response evaluation. PDL1 TPS scores in pretreatment biopsies ranged from 0 to 100%. Most important, neither any of the more frequent molecular alterations nor PDL1 status correlated with pCR. Despite overall correlation of therapy response in PT and LN, heterogeneous response in the different compartments was observed.
Conclusions
Histopathological regression grading of NSCLC after neoadjuvant IO treatment should include submitting of the entire tumor bed and reporting of percentage of residual vital tumor RVT. Our multicenter registry is a valuable tool to investigate novel predictors of IO response which are urgently needed to improve outcomes of NSCLC patients.
Funding
Felix Elsner was supported by the Interdisciplinary Center for Clinical Research (IZKF) at the University Hospital of the Friedrich-Alexander-Universität (FAU) (ELAN Project P150).
Disclosure
C. Kümpers: Financial Interests, Personal, Invited Speaker: AstraZeneca, Merck Sharp & Dohme and Boehringer Ingelheim. M. von Laffert: Financial Interests, Personal, Invited Speaker: AstraZeneca, Merck, Roche, Sanofi, Boehringer Ingelheim, Janssen, Bristol Myers Squibb. K. Steinestel: Financial Interests, Personal, Invited Speaker: AstraZeneca, Merck Sharp & Dohme, Bristol Meyers Squibb, Sanofi and Boehringer Ingelheim. All other authors have declared no conflicts of interest.