039 Attig | Immune monitoring Recommendations for HLA-peptide multimer staining experiments - Results from the second HLA-peptide multimer proficiency phase organized by the Cancer Immunotherapy Consortium Sebastian Attig 1 *, Leah Price 2 *, Sylvia Janetzki 3 , Michael Kalos 4 , Michael Pride 5 , Lisa Mc Neil 5 , Tim Clay 6 , Jianda Yuan 7 , Kunle Odunsi 8 , Axel Hoos 9 , Pedro Romero 10 , Cedrik M. Britten 1,11 for the CRI-CIC Assay Working Group 1 Division of Translational and Experimental Oncology, Department of Internal Medicine III, University Medical Center of the Johannes-Gutenberg University, Mainz, Germany 2 Department of Biostatistics, New York University, New York, NY USA 3 ZellNet Consulting, Inc., Fort Lee, NJ USA 4 Department of Pathology and Laboratory Medicine, University of Pennsylvania School of Medicine, Abramson Family Cancer Research Institute, Philadelphia, PA USA 5 ZellNet Consulting, Inc., Fort Lee, NJ, USA 6 Surgery and Immunology, Duke University Medical Center, Durham, NC, USA 7 Ludwig Center for Cancer Immunotherapy, Immunology Program, Sloan-Kettering Institute, New York, NY USA 8 Departments of Gynecologic Oncology and Immunology, Roswell Park Cancer Institute, Buffalo, NY, USA 9 Bristol-Myers Squibb, Wallingford, CT USA 10 Division of Clinical Onco-Immunology, Ludwig Institute for Cancer Research, Lausanne Branch, University Hospital (CHUV), Lausanne, Switzerland 11 Clinical Development, BioNTech AG, Mainz, Germany 82 The Cancer research Institute‘s Cancer Immuno- therapy Consortium (CRI-CIC) has conducted a HLA-peptide multimer (MULTIMER) proficiency panel focusing on the impact of DUMP channel use. The study showed that the introduction of a dump channel did not impact on the detection rate of participating labs but did reduce the non-specific MUL- TIMER binding within the group. Both the use of DUMP channel and dead cell marker may decrease the amount of false positive events in CD8-positive population thus leading to a lower limit of detection of the test and provide a more accurate measure of the true MULTIMER specific binding. In 88% of all the CMV-MULTIMER replicates a response was detected, demonstrating that low frequency CMV responses were successfully detected by most of the labs. Variation of duplicate staining was below 30% in 70% of participating labs indicating a very good reproducibility of results even for low frequency T cell responses. Introduction of a dump channel also decreased the variability in reported frequencies of pp65-specific CD8 T cells across the group. However, the response detection rates for the Melan-A responses were much lower which was due to the particular staining characteristics of the Melan-A-specific MULTIMER. Results from this proficiency panel phase clearly confirm the value of previously published harmonization guidelines, and have led to additional recommendations on assay performance and how to best present data from MULTIMER experiments.
Cellular therapy 83