Identification of a Titin-derived HLA-A1-presented peptide as a cross-reactive target for engineered MAGE A3-directed T cells.
MAGE A3, which belongs to the family of cancer-testis antigens, is an attractive target for adoptive therapy given its reactivation in various tumors and limited expression in normal tissues. We developed an affinity-enhanced T cell receptor (TCR) directed to a human leukocyte antigen (HLA)-A*01-restricted MAGE A3 antigen (EVDPIGHLY) for use in adoptive therapy. Extensive preclinical investigations revealed no off-target antigen recognition concerns; nonetheless, administration to patients of T cells expressing the affinity-enhanced MAGE A3 TCR resulted in a serious adverse event (SAE) and fatal toxicity against cardiac tissue. We present a description of the preclinical in vitro functional analysis of the MAGE A3 TCR, which failed to reveal any evidence of off-target activity, and a full analysis of the post-SAE in vitro investigations, which reveal cross-recognition of an off-target peptide. Using an amino acid scanning approach, a peptide from the muscle protein Titin (ESDPIVAQY) was identified as an alternative target for the MAGE A3 TCR and the most likely cause of in vivo toxicity. These results demonstrate that affinity-enhanced TCRs have considerable effector functions in vivo and highlight the potential safety concerns for TCR-engineered T cells. Strategies such as peptide scanning and the use of more complex cell cultures are recommended in preclinical studies to mitigate the risk of off-target toxicity in future clinical investigations.
Immunocore Ltd., 57c Milton Park, Jubilee Avenue, Abingdon, OX14 4RX, UK.
Brian J
BJ
Cameron
Andrew B
AB
Gerry
Joseph
J
Dukes
Jane V
JV
Harper
Vivekanandan
V
Kannan
Frayne C
FC
Bianchi
Francis
F
Grand
Joanna E
JE
Brewer
Minnal
M
Gupta
Gabriela
G
Plesa
Giovanna
G
Bossi
Annelise
A
Vuidepot
Alex S
AS
Powlesland
Alison
A
Legg
Katherine J
KJ
Adams
Alan D
AD
Bennett
Nicholas J
NJ
Pumphrey
Daniel D
DD
Williams
Gwendolyn
G
Binder-Scholl
Irina
I
Kulikovskaya
Bruce L
BL
Levine
James L
JL
Riley
Angel
A
Varela-Rohena
Edward A
EA
Stadtmauer
Aaron P
AP
Rapoport
Gerald P
GP
Linette
Carl H
CH
June
Namir J
NJ
Hassan
Michael
M
Kalos
Bent K
BK
Jakobsen
D000595:Amino Acid Sequence; D017951:Antigen Presentation / Q000276:immunology*; D000951:Antigens, Neoplasm / Q000737:chemistry / Q000276:immunology*; D000970:Antineoplastic Agents / Q000494:pharmacology; D002454:Cell Differentiation / Q000187:drug effects; D045744:Cell Line, Tumor; D064211:Connectin / Q000737:chemistry* / Q000276:immunology; D003429:Cross Reactions / Q000187:drug effects / Q000276:immunology*; D057809:HEK293 Cells; D015788:HLA-A1 Antigen / Q000276:immunology*; D006801:Humans; D008213:Lymphocyte Activation / Q000187:drug effects; D008969:Molecular Sequence Data; D032383:Myocytes, Cardiac / Q000187:drug effects / Q000378:metabolism; D009363:Neoplasm Proteins / Q000737:chemistry / Q000276:immunology*; D010455:Peptides / Q000737:chemistry / Q000276:immunology*; D015202:Protein Engineering; D011948:Receptors, Antigen, T-Cell / Q000378:metabolism; D013601:T-Lymphocytes / Q000187:drug effects / Q000378:metabolism*
D000951:Antigens, Neoplasm; D000970:Antineoplastic Agents; D064211:Connectin; D015788:HLA-A1 Antigen; C072013:MAGEA3 protein, human; D009363:Neoplasm Proteins; D010455:Peptides; D011948:Receptors, Antigen, T-Cell