Diffuse large B cell lymphoma (DLBCL) is the most common lymphoma diagnosed in the United States with approximately 30,000 new cases recognized each year. Unfortunately, 40% of DLBCL patients will develop relapsed or refractory disease following current standard of care treatment, which is associated with poor clinical outcomes and a median survival of only 6 months. More effective therapies are therefore needed for the management of relapsed/refractory DLBCL.

Recently, the development of anti-programmed death-1 receptor (anti-PD-1) immunotherapies has transformed the treatment of several cancer types, and are allowing many cancer patients to live longer and with fewer side effects compared to conventional chemotherapy. Anti-PD-1 therapies however are only modestly effective in DLBCL (15% response rate), and predictive biomarkers are needed to identify those patients who are most likely to benefit from treatment. To this end, our lab has identified a novel predictive biomarker, which is associated with clinical response to anti-PD-1 therapy in retrospective analyses of DLBCL-treated patients. This biomarker is defined by the presence of PD-L1 gene alterations within tumor specimens (amplifications and activating translocations), which are readily identified using standard and cost- effective diagnostic tests such as fluorescent in-situ hybridization. Importantly, we have also demonstrated that PD-L1 gene-altered DLBCLs are characterized by “inflamed” tumor microenvironments, which we believe is a critical prerequisite to anti-PD-1 immunotherapy response. How the DLBCL immune environment is regulated, and whether PD-L1 gene alterations can prospectively predict response to anti-PD-1 therapy however is not known, which represent critical knowledge gaps. The overall objective of this grant was therefore to 1) develop a clinical trial to prospectively validate the use of PD-L1 gene alterations as a biomarker of response to anti-PD-1 therapy in relapsed/refractory DLBCL patients, and 2) investigate the mechanisms regulating the immune landscape of DLBCL tumors.
In regards to the first objective of this grant, we have successfully applied for an were awarded an investigator-initiated clinical trial to evaluate PD-L1 gene alterations as a biomarker of clinical response to pembrolizumab in relapsed/refractory DLBCL patients. During the funding period, we have written and finalized the clinical trial protocol, and collaborated with our Cytogenetics Department to validate the fluorescent in-situ hybridization diagnostic test to identify PD-L1 gene alterations. The clinical trial was then officially opened in 2020, and we are very excited to report that the first two patients enrolled on study have responded to treatment. Thus, these early data suggest that screening for the presence of PD-L1 gene alterations is a promising method to identify DLBCL patients who may benefit for pembrolizumab therapy, and will hopefully provide additional treatment options for patients using a tailored and personalized treatment approach.

In parallel with the development of our above clinical trial, we have also generated new data to investigate the molecular regulation of the immune landscape of DLBCL. In particular, we have interrogated large-scale DLBCL genomic datasets containing over 1,000 DLBCL samples to identify the salient genomic features of DLBCL tumors that harbor “inflamed” and “non-inflamed” tumor microenvironments as defined by gene expression analyses. These studies have led to our recent review in BLOOD that provides an overview of our current understanding of the key molecular determinants of the immune landscape of lymphomas and their responsiveness to immune-checkpoint blockade therapy. These data have also led to an Oral Abstract presentation at American Society of Hematology and a Poster presentation at American Association for Cancer

Research, and were the basis for a successful application for a K12 NIH award. Moving forward, we now seek to leverage this information to identify targetable pathways that can enhance the clinical effectiveness of immune-based therapies in lymphoma.

Overall, in the time since receiving this CRF YIA, our research group has had significant productivity and scientific impact within the field of lymphoma immunotherapy. There have been eight publications, several abstract presentations, and multiple grant awards received. The most impactful accomplishment however has been the development of a novel biomarker-driven clinical trial that seeks to define a new generation of personalized and precision-based immunotherapy for DLBCL.

Funding Use:
These funds were used to support costs associated with laboratory reagents, administrative costs, and the salary of collaborators (bioinformatics and biostatistical) and the principal investigator.

Expansion Plans:
Our biomarker-driven clinical trial continues to enroll patients and has been opened at additional large-volume cancer centers given the early efficacy signal and strong study rationale. We also envision PD-L1 gene alterations becoming a truly tissue-agnostic biomarker similar to the use of microsatellite instability testing for anti-PD-1 therapy since PD-L1 gene alterations are present in other cancer types. Lastly, the data generated during this Award will serve as the basis for future NIH grant applications that seek to uncover the molecular mechanisms regulating the immune microenvironment in DLBCL, and to identify novel combination treatment strategies that can improve the effectiveness of cancer immunotherapies for lymphoma patients.