LCL161 enhances expansion and survival of engineered anti-tumor T cells but is restricted by death signaling

Arya Afsahi; Christopher M Silvestri; Allyson E Moore; Carly F Graham; Kaylyn Bacchiochi; Martine St-Jean; Christopher L Baker; Robert G Korneluk; Shawn T Beug; Eric C LaCasse; Jonathan L Bramson

doi:10.3389/fimmu.2023.1179827

LCL161 enhances expansion and survival of engineered anti-tumor T cells but is restricted by death signaling

Front Immunol. 2023 Apr 17:14:1179827. doi: 10.3389/fimmu.2023.1179827. eCollection 2023.

Authors

Arya Afsahi^{1

2

3}, Christopher M Silvestri^{1

2

3}, Allyson E Moore^{1

2

3}, Carly F Graham^{1

2

3}, Kaylyn Bacchiochi^{2

3}, Martine St-Jean⁴, Christopher L Baker^{1

2

3}, Robert G Korneluk⁴, Shawn T Beug^{4

5

6}, Eric C LaCasse⁴, Jonathan L Bramson^{1

2

3}

Affiliations

¹ Centre for Discovery in Cancer Research, McMaster University, Hamilton, ON, Canada.
² McMaster Immunology Research Center, McMaster University, Hamilton, ON, Canada.
³ Department of Medicine, McMaster University, Hamilton, ON, Canada.
⁴ Apoptosis Research Centre, Children's Hospital of Eastern Ontario Research Institute, Ottawa, ON, Canada.
⁵ Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, ON, Canada.
⁶ Centre for Infection, Immunity and Inflammation, University of Ottawa, Ottawa, ON, Canada.

Abstract

Background: The genesis of SMAC mimetic drugs is founded on the observation that many cancers amplify IAP proteins to facilitate their survival, and therefore removal of these pathways would re-sensitize the cells towards apoptosis. It has become increasingly clear that SMAC mimetics also interface with the immune system in a modulatory manner. Suppression of IAP function by SMAC mimetics activates the non-canonical NF-κB pathway which can augment T cell function, opening the possibility of using SMAC mimetics to enhance immunotherapeutics.

Methods: We have investigated the SMAC mimetic LCL161, which promotes degradation of cIAP-1 and cIAP-2, as an agent for delivering transient costimulation to engineered BMCA-specific human TAC T cells. In doing so we also sought to understand the cellular and molecular effects of LCL161 on T cell biology.

Results: LCL161 activated the non-canonical NF-κB pathway and enhanced antigen-driven TAC T cell proliferation and survival. Transcriptional profiling from TAC T cells treated with LCL161 revealed differential expression of costimulatory and apoptosis-related proteins, namely CD30 and FAIM3. We hypothesized that regulation of these genes by LCL161 may influence the drug's effects on T cells. We reversed the differential expression through genetic engineering and observed impaired costimulation by LCL161, particularly when CD30 was deleted. While LCL161 can provide a costimulatory signal to TAC T cells following exposure to isolated antigen, we did not observe a similar pattern when TAC T cells were stimulated with myeloma cells expressing the target antigen. We questioned whether FasL expression by myeloma cells may antagonize the costimulatory effects of LCL161. Fas-KO TAC T cells displayed superior expansion following antigen stimulation in the presence of LCL161, suggesting a role for Fas-related T cell death in limiting the magnitude of the T cell response to antigen in the presence of LCL161.

Conclusions: Our results demonstrate that LCL161 provides costimulation to TAC T cells exposed to antigen alone, however LCL161 did not enhance TAC T cell anti-tumor function when challenged with myeloma cells and may be limited due to sensitization of T cells towards Fas-mediated apoptosis.

Keywords: LCL161; SMAC mimetics; adoptive T cell therapies; cancer immunotherapy; engineered T cells; multiple myeloma.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Cell Line, Tumor
Humans
Inhibitor of Apoptosis Proteins / genetics
Inhibitor of Apoptosis Proteins / metabolism
Multiple Myeloma* / drug therapy
NF-kappa B* / metabolism

Substances

LCL161
NF-kappa B
Inhibitor of Apoptosis Proteins

Grants and funding

This research was funded by the Samuel Family Foundation, Inc. AA received support from the Ontario Graduate Scholarship and the Samuel Scholars Program. JB is supported by a Canadian Research Chair in Translational Cancer Immunology and the John Bienenstock Chair in Molecular Medicine. Additional funding support was through a CIHR Foundation grant to RK.