Checkpointinhibition in lung cancer – How to distinguish pseudoprogression from progressive disease

Abstract

Introduction: Checkpointinhibition has become a new paradigm in second-line treatment of metastatic NSCLC. Response rates in Phase II and III trials ranged from 15-20%. In clinical practice it is hard to distinguish pseudoprogression due to an inflammatory increase of tumor volume from really progressive cancer.

Aims and objectives: We tried to detect repetitive patterns to distinguish pseudoprogression from progressive cancer.

Material and methods: All patients treated at our institution with a checkpoint-inhibitor so far in any line of treatment, start of treatment before February 15´th 2016, were evaluated regarding: tumor response, specific signs within the CT-scans, histological and cytological features, PD-L1 expression and driver mutations if available, lab values, other clinical signs.

Results: Since the first patient in October 2013 67 patients (median age 65.8y, 38% female, 34 squamous histology, 30 adenocarcinoma 2 LCNEC, 2 SCLC) were started on treatment with various checkpoint-inhibitors (Atezolizumab 25 patients, Nivolumab 36, Ipilimumab and Nivolumab 2, Durvalumab 1, Tremelimumab plus Durvalumab 3). So far there is no unequivocal pattern detectable that definitively distinguishes pseudoprogression from progressive cancer. However there are hints in terms of specific CT-signs, clinical, histologic and cytological features. Detailed results after a minimum follow up of six months will be presented at the meeting.

Conclusion: Further research evaluating CT, clinical, histological and cytological details might help to detect patterns distinguishing pseudoprogression from progressive cancer.