Abstract
Congenital DNA mismatch repair defects (dMMR), such as Lynch Syndrome, predispose patients to a variety of cancers and account for approximately 1% of glioblastoma cases. While few therapeutic options exist for glioblastoma, checkpoint blockade therapy has proven effective in dMMR tumors. Here we present a case study of a male in their 30s diagnosed with dMMR glioblastoma treated with pembrolizumab who experienced a partial response to therapy. Using a multiplex IHC analysis pipeline on archived slide specimens from tumor resections at diagnosis and after therapeutic interventions, we quantified changes in the frequency and spatial distribution of key cell populations in the tumor tissue. Notably, proliferating (KI67+) macrophages and T cells increased in frequency as did other KI67+ cells within the tumor. Therapeutic intervention remodeled the cellular spatial distribution in the tumor leading to a greater frequency of macrophage/tumor cell interactions and T cell/T cell interactions, highlighting impacts of checkpoint blockade on tumor cytoarchitecture and revealing spatial patterns that may indicate advantageous immune interactions in glioma and other solid tumors treated with these agents.
Insight This work sheds light on the capacity of checkpoint blockade therapy to modulate the immune microenvironment in DNA mismatch repair deficient glioblastoma, highlights the utility of window-of-opportunity clinical trials in patient selection of immunomodulatory therapies, and demonstrates the feasibility and utility of mapping cellular interactions associated with therapeutic responses in gliomas and other solid tumors.
Statement regarding non-clinical trial status We confirmed with a treating neurologist in this case that the treatment received by the individual whose samples are studied was part of routine clinical care and not a clinical trial, as the patient was previously diagnosed with Lynch syndrome (a mismatch repair deficiency). The use of pembrolizumab is recommended for treatment of tumors with high mutational burden due to mismatch repair deficiency and is currently considered standard of care for these tumors. Additionally, though the intervention and outcome are detailed in the manuscript, the focus of the manuscript is on reporting changes observed in the immune microenvironment at different points in the clinical trajectory - a retrospective analysis performed after clinical care was complete.
Competing Interest Statement
DBJ has served on advisory boards or as a consultant for BMS, Catalyst Biopharma, Iovance, Jansen, Mallinckrodt, Merck, Mosaic ImmunoEngineering, Novartis, Oncosec, Pfizer, Targovax, and Teiko, and has received research funding from BMS and Incyte.
Funding Statement
Research was supported by the following funding resources: R01 NS118580 (R.A.I, A.A.B), K00 CA212447 (T.B.), T32 CA009592 (T.B.), the Michael David Greene Brain Cancer Fund (R.A.I.), the Southeastern Brain Tumor Foundation (R.A.I.), a gift from Daniel F. Hewins (R.A.I, A.A.B), and the Vanderbilt-Ingram Cancer Center (VICC, P30 CA68485). The Translational Pathology Shared Resource is supported by NCI/NIH Cancer Center Support Grant P30CA068485 and the Shared Instrumentation Grants S10 OD023475-01A1, S10 OD016355, and IS1BX003154.
Author Declarations
I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained.
Yes
The details of the IRB/oversight body that provided approval or exemption for the research described are given below:
IRB of Vanderbilt University Medical Center gave ethical approval for this work (protocol 181970). Statement regarding non-clinical trial status: We confirmed with a treating neurologist in this case that the treatment received by the individual whose samples are studied was part of routine clinical care and not a clinical trial, as the patient was previously diagnosed with Lynch syndrome (a mismatch repair deficiency). The use of pembrolizumab is recommended for treatment of tumors with high mutational burden due to mismatch repair deficiency and is currently considered standard of care for these tumors. Additionally, though the intervention and outcome are detailed in the manuscript, the focus of the manuscript is on reporting changes observed in the immune microenvironment at different points in the clinical trajectory - a retrospective analysis performed after clinical care was complete.
I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals.
Yes
I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance).
Yes
I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable.
Yes
Footnotes
Financial Support: Research was supported by the following funding resources: R01 NS118580 (R.A.I, A.A.B), K00 CA212447 (T.B.), T32 CA009592 (T.B.), the Michael David Greene Brain Cancer Fund (R.A.I.), the Southeastern Brain Tumor Foundation (R.A.I.), a gift from Daniel F. Hewins (R.A.I, A.A.B), and the Vanderbilt-Ingram Cancer Center (VICC, P30 CA68485). The Translational Pathology Shared Resource is supported by NCI/NIH Cancer Center Support Grant P30CA068485 and the Shared Instrumentation Grants S10 OD023475-01A1, S10 OD016355, and IS1BX003154.
Conflict of Interest Disclosure: DBJ has served on advisory boards or as a consultant for BMS, Catalyst Biopharma, Iovance, Jansen, Mallinckrodt, Merck, Mosaic ImmunoEngineering, Novartis, Oncosec, Pfizer, Targovax, and Teiko, and has received research funding from BMS and Incyte.
Data Availability
Datasets analyzed in this manuscript will be made available for reviewers and at the time of publication. Transparent analysis scripts for datasets in this manuscript are publicly available on the Ihrie Lab Github page (https://github.com/ihrie-lab/CASSATT) with open-source code and commented python analysis walkthroughs.