Purpose Immune checkpoint inhibitors have shown efficacy in patients with microsatellite instability-high/mismatch repair-deficient (MSI-H/dMMR) gastrointestinal (GI) cancers. However, depth and duration of clinical response is not uniform. We assessed tumor mutation burden (TMB) as a response marker in patients with GI cancers treated with immune checkpoint inhibitors. Methods Detailed clinical and response data were collected from six patients with metastatic MSI-H/dMMR GI cancers treated with immune checkpoint inhibitors. Efficacy was assessed by Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1. Tumors and matched normal tissue were profiled by targeted next generation sequencing (127 gene panel, size 0.8 Mb). Impact of included mutation types, germline filtering methodology and different variant allele frequency thresholds on TMB estimation was assessed. Results Objective radiographic responses were observed in all six patients, and complete response was achieved in two of the six patients. Responses were durable (minimum 25 months). TMB estimates were clearly above the two recently reported cut-offs for metastatic colorectal cancer of 12 or 37 mutations per megabase for five of six patients, respectively, while one patient had borderline TMB elevation. TMB did not show an association with extent and duration of response but was influenced by included mutation types, germline filtering method and variant allele frequency threshold. Conclusion Our case series confirms the clinical benefit of immune checkpoint blockade in patients with metastatic MSI-H/dMMR GI cancers and illustrates the vulnerability of TMB as predictive marker in a subset of patients. Electronic supplementary material The online version of this article (10.1007/s00432-020-03335-2) contains supplementary material, which is available to authorized users.

Introduction: Cancer patients (pts) suffer from a significant amount of psychosocial distress related to tumor disease itself or straining treatments. Despite recommendations how to screen for and to deal with psychosocial distress in cancer pts, data about implementation of psycho-oncological interventions (poi) in outpatient settings of cancer pts is scarce. Aim of this study was to identify outpatients with cancer in need of poi and to evaluate different assessment instruments. Methods: N=200 outpatients with haemato-/oncological malignancies were interviewed between October 2015 and December 2017 at the University Hospital Mannheim using the Basic Documentation for Psycho-Oncology (PO-Bado) and the Hornheider Screening Instrument (HSI) – both clinician-administered assessment tools – followed by descriptive, univariate and agreement analysis. Results: N=61 cancer pts (31%) were identified to be in need for poi considering the results of both questionnaires. The number of identified patients in need of poi was lower when analyzing the results of the PO-Bado (n=42, 21%) and the HSI (n=39, 20%) separately. The degree of agreement the results of PO-Bado and HSI was low (kappa=0.3655). Several factors like gender, age and diagnosis were identified to have significant impact on the need for poi (p≤0.05). Discussion/Conclusion: Our study underlines, that different screening instruments for psychosocial distress may identify disparate populations of cancer pts. The study data also revealed significant characteristics that might be associated with elevated levels of psychosocial distress and a clear indication for poi. However, further analyses on larger populations of cancer pts are needed to provide information how to transfer positive screening to poi in clinical routine.