-Author name in bold denotes the presenting author
-Asterisk * with author name denotes a Non-ASH member
Clinically Relevant Abstract denotes an abstract that is clinically relevant.

PhD Trainee denotes that this is a recommended PHD Trainee Session.

Ticketed Session denotes that this is a ticketed session.

1529 Comparison of Anti-PD1, Anti-CTLA4 and Anti-TIM3 in Treatment of AML Patients with Single-Cell Transcriptomics Displays Different Effects on Immune Subtypes

Program: Oral and Poster Abstracts
Session: 618. Acute Myeloid Leukemias: Biomarkers and Molecular Markers in Diagnosis and Prognosis: Poster I
Hematology Disease Topics & Pathways:
Research, Acute Myeloid Malignancies, AML, Translational Research, Diseases, Treatment Considerations, Biological therapies, Immunotherapy, Myeloid Malignancies
Saturday, December 7, 2024, 5:30 PM-7:30 PM

Sofia Forstén1,2,3*, Livius Penter, MD4,5, Oscar E. Brück, MD, PhD6*, Johannes Smolander, PhD1,2,3*, Karita Peltonen, PhD1,2,3*, Harri Lähdesmäki, PhD7*, Mika Kontro, MD, PhD8, Kimmo Porkka, MD, PhD1,2,3,8, Hussein A. Abbas, MD, PhD9,10, Catherine J. Wu, MD11,12,13*, Jani Huuhtanen, MD, PhD1,2,3,7* and Satu Mustjoki, MD, PhD1,2,3

1Translational Immunology Research Program, University of Helsinki, Helsinki, Finland
2ICAN Digital Precision Cancer Medicine Flagship, University of Helsinki and Helsinki University Hospital Comprehensive Cancer Center, Helsinki, Finland
3Hematology Research Unit Helsinki, Department of Hematology, University of Helsinki and Helsinki University Hospital Comprehensive Cancer Center, Helsinki, Finland
4BIH Biomedical Innovation Academy Berlin Institute of Health at Charité - Universitätsmedizin Berlin, Berlin, Germany
5Department of Hematology, Oncology, and Tumorimmunology Charité - Universitätsmedizin Berlin, Berlin, Germany
6Hematoscope Lab, Comprehensive Cancer Center & Center of Diagnostics, Helsinki University Hospital & University of Helsinki, Helsinki, Finland
7Department of Computer Science, Aalto University, Espoo, Finland
8Department of Hematology, Helsinki University Hospital Comprehensive Cancer Center, Helsinki, Finland
9Department of Leukemia, The University of Texas MD Anderson Cancer Center, Houston, TX
10Department of Genomic Medicine, Division of Cancer Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX
11Broad Institute of MIT and Harvard, Cambridge, MA
12Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, MA
13Harvard Medical School, Boston, MA

Introduction

Although immune checkpoint inhibitors (ICI) in combination with hypomethylating agents (HMA) have had limited activity in acute myeloid leukemia (AML), a subset of patients has achieved durable responses. This emphasizes the need to define the immunomodulatory effects and immune phenotypes that associate with response to different ICIs. Further, understanding individual responses can point towards new immunotherapeutic strategies in AML.

Methods

We combined single-cell RNA and T cell receptor sequencing (scRNA+TCRαβ-seq) data from AML patients (N=37) treated on clinical trials with the combination of HMA with either anti-CTLA4 (responders CR/CRi/PR: 10/18; Penter et al., Blood 2023), anti-PD1 (CR/CRi/PR: 5/12; Abbas Hu et al., Nat Comm 2021, Goswami et al., JITC 2022) or anti-TIM3 (CR/CRi/PR: 3/7; Huuhtanen et al., ASH 2021). Overall, we pooled together 122 longitudinal bone marrow samples and obtained 605,877 quality-controlled and harmonized cells, making it the largest scRNA+TCRαβ-seq dataset of AML treated with immunotherapy thus far.

Results

First, we defined immune checkpoint expression across immune cells. Expression of PD1 (PDCD1) and CTLA4 was mostly restricted to T cells, where PD1 was mainly expressed in CD8+ T cells (Tem, Temra) and CTLA4 in CD4+ T cells (Treg). This contrasted with TIM3 (HAVCR2), that was highly expressed in different NK cells (CD56bright, CD56dim, adaptive NK cells) and different myeloid cells, with lower levels in CD8+ T cells, suggesting different treatment effects.

As immune checkpoint expression profiles differed particularly in NK cells, we explored their role in ICI responses. Responders in all treatment groups had more mature (cytotoxic CD56dim and memory-like adaptive) NK cells prior to treatment than non-responders (p=0.016). Even though there was no overall significant difference in NK cell expansion, responders to anti-TIM3 or anti-PD1 had more transcriptional changes (number of DEGs) in NK cells, than those treated with anti-CTLA4. Finally, anti-PD1 upregulated IFN-γ and IFN-α pathways, while anti-TIM3 upregulated NF-κB pathway, suggesting different activation mechanisms.

Given high PD1 expression in CD8+ T cells, we wondered whether this would translate into different ICI-related mechanisms of response. Indeed, anti-PD1 responders upregulated IFN-g and IFN-a pathways, unlike anti-TIM3 and anti-CTLA4 responders. Additionally, when analysing scTCRab data, more CD8+ T cell clones expanded (Fisher’s exact test) in response to anti-PD1 (mean number of expanding clones 20.7, p=0.036) and to anti-TIM3 (mean 23.1, p=2.5x10-7) than to anti-CTLA4 (mean 6.6). However, expanding T cell clones did not correlate with treatment outcomes and were also detected in non-responders.

Since T cell clones also expanded in non-responders, we asked whether their phenotypes or frequencies associated with response to ICI. In responders to anti-PD1, we found large expanded T cell clones (>1% of CD8+ TCR repertoire) whose transcriptional profiles shifted from an exhausted (PDCD1+, TOX+) to a cytotoxic CD8+ Temra phenotype, consistent with reversal of T cell exhaustion. In contrast, in anti-TIM3 responders, the size of expanding T cell clones was small (<0.1% of CD8+ TCR repertoire in pre-treatment samples), and we noted decreased CD8+ Temra populations while exhausted T cells increased. This suggests that anti-TIM3 might not reverse T cell exhaustion, but potentially increases priming of T cells. After anti-CTLA4, no clear differences in the phenotypes of the expanded CD8+ T cell clones were noted, consistent with the expression of CTLA4 on CD4+ T cells.

Conclusions

Our analysis suggests different immune activation mechanisms for anti-PD1, anti-CTLA4, and anti-TIM3 in AML. Both anti-PD1 and anti-CTLA4 exhibited more effects on T cells compared to anti-TIM3. In responders, anti-PD1 therapy upregulated IFN-γ and IFN-α pathways and reversed exhaustion in CD8+ T cell clones. Conversely, anti-TIM3 had more pronounced effects on NK cells via upregulation of NF-κB pathway in responders. None of the immune cell populations were able to predict the treatment response, highlighting that the choice of ICI should be personalized to each patient.

Disclosures: Brück: Astellas: Consultancy; Novartis: Consultancy; Sanofi: Consultancy; Roche: Consultancy; Amgen: Consultancy; GSK: Consultancy; Pfizer: Research Funding; Gilead Sciences: Research Funding; Hematoscope Ltd: Current equity holder in private company. Kontro: Servier: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Astellas: Consultancy, Membership on an entity's Board of Directors or advisory committees; Pfizer: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Novartis: Membership on an entity's Board of Directors or advisory committees; BMS: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; AbbVie: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Faron Pharmaceuticals: Consultancy; Immedica: Membership on an entity's Board of Directors or advisory committees. Porkka: Novartis: Research Funding; Incyte: Research Funding; Roche: Research Funding. Abbas: Blueprint Medicines Corporation: Research Funding; Ascentage: Research Funding; Illumina: Honoraria, Other: Inkind Support, Research Funding; Molecular Partners: Consultancy; Alamar Biosciences: Honoraria; GlaxoSmithKline: Research Funding; Genentech: Research Funding; Enzyme By Design: Research Funding. Wu: Pharmacyclics: Research Funding; Repertoire: Membership on an entity's Board of Directors or advisory committees; BioNtech, Inc: Current equity holder in publicly-traded company; Adventris: Membership on an entity's Board of Directors or advisory committees; Aethon Therapeutics: Membership on an entity's Board of Directors or advisory committees. Mustjoki: Novartis: Honoraria, Research Funding; Pfizer: Research Funding; Dren Bio: Honoraria; BMS: Honoraria, Research Funding.

*signifies non-member of ASH