Impact of a PD-L1 Learning Collaborative: outcomes from a mixed-methods evaluation

Abstract Introduction/Objective PD-L1 Immunohistochemistry testing is often required to determine eligibility for immune checkpoint inhibitor therapy. An ASCP PD-L1 Learning Collaborative (LC) was formed aiming to: 1) identify ways to streamline PD-L1 testing; 2) encourage members to locally implement changes; and 3) develop a resource guide for the community. Methods/Case Report The PD-L1 LC (n=38 pathologists and laboratory professionals) participated in 3 activities: 1) 4 meetings in which LC members discussed current literature and practice; 2) 3 30-minute on-demand, credit-bearing panel videos, in which selected LC members summarized the LC outputs and shared their experiences; and 3) a guide summarizing resources relevant to streamlining PD-L1 testing. The mixed-methods evaluation included: 1) five- minute surveys before (n=24), immediately after (n=11) and 7-months post-LC (n=17); 2) polling questions (2-4 per meeting); 3) semi-structured interviews (n=5). Quantitative data was analysed using descriptive and inferential analysis, qualitative data using a thematic analysis / inductive reasoning approach. Results (if a Case Study enter NA) Baseline data confirmed delays in testing caused by unstandardized PD-L1 testing processes and suboptimal confidence in PD-L1 validation and methodologies. Post-LC, members self-reported perceived increased knowledge and higher confidence levels regarding discussion of PD-L1 scientific evidence and best practices. At the 7-month follow-up, 59% of respondents reported at least one PD-L1-related practice change, with 29% of participants selecting:1) Improving protocols for specimen acquisition, handling, or processing; 2) Improving communication with multidisciplinary care team; 3) Optimizing biomarker testing workflows. Remaining suboptimal knowledge post-LC suggests need for further educational efforts. Participants identified “Tumor-specific considerations” as the main resource missing for PD-L1 testing. Conclusion A learning collaborative has shown impact in improving PD-L1 testing processes and related practices among a group of pathology professionals. The group successfully made available three panel videos and a resource guide, and PD-L1-related practice changes were reported. Future initiatives should address remaining gaps and develop tumor-specific PD-L1 testing considerations.