Chimeric antigen receptor T cell therapy: Revolutionizing cancer treatment

Table 1 Comparative features of major variants of chimeric antigen receptor T cell design components[13-17]

Component	Variant	Key characteristics	Design considerations	Functional impact
ARD	Murine ScFv	High specificity; high immunogenicity; low persistence	Suitable for short-term efficacy	Strong initial response; risk of immune rejection
	Humanized ScFv	Moderate specificity and immunogenicity; improved persistence	Balances efficacy and safety	Enhanced persistence with reduced immunogenicity
	Fully human ScFv	Variable specificity; lowest immunogenicity; high persistence	Ideal for long-term or clinical use	Best suited for chronic and relapsed settings
	Ligand-receptor ARD	Variable specificity; low immunogenicity; high persistence	High safety and efficacy	Targets stress-induced ligands in solid tumors
	TCRm ARD	High specificity; moderate immunogenicity; low persistence	Low safety for chances of off target toxicity; High efficacy	Effective for tumors lacking surface antigens
	VLR	High specificity; high immunogenicity; moderate persistence	Low safety; Promising efficacy	Promising in vitro cytotoxicity
Hinge (spacer) domain	MUC1	Long, no FcγR binding	Effective for membrane-proximal antigens, particularly those with complex glycosylation patterns	modulate immune signaling and enhance tumor-specific responses
	IgG1/4	Varying length; FcγR binding	Effective for membrane-proximal antigens	Requires Fc modification to avoid off-target activation
	CD8α	Short; no FcγR binding	Useful for far membrane epitopes	Enhances synapse formation with minimal off-target risk
	CD28	Short; no FcγR binding	Useful for far membrane epitopes	Promotes stable orientation of CAR
TMD	CD3ζ	TCR-integrated; part of native TCR complex	May synergize with CD3ζ ISD	Low stability; can support natural TCR-like signaling
	CD8α	Stable; commonly paired with CD8α hinge	Improves CAR expression	superior stability and expression
	CD28	Robust membrane anchoring	Common in 2nd-generation CARs	superior stability and expression
	ICOS	High T-cell persistence and function, especially in CD4+ T cells	excellent CAR-T cell tenacity	Efficient anti-cancer application
CSD	CD28	Strong initial T cell activation; IL-2, IL-4, IL-10 secretion; promotes effector T cell differentiation; moderate persistence	Drives effector phenotype	Rapid tumor cytotoxicity with limited duration
	4-1BB (CD137)	Oxidative phosphorylation; prolonged persistence	Promotes memory T cell formation	Sustained activity and long-term tumor control in chronic malignancies

ICOS: Inducible T cell co-stimulator; MUC1: Mucin-1; ARD: Antigen recognition domain; ScFv: Single chain variable fragment; TCRm: T cell receptor-mimicking; VLR: Variable lymphocyte receptors; CAR: Chimeric antigen receptor; TMD: Transmembrane domain; CSD: Co-stimulatory domain.

Table 2 Summary of chimeric antigen receptor generations

CAR generation	Intracellular domain structure	Key features and limitations	Pivotal trials1	Approved/trial phase
1st	ISD (e.g., CD3ζ); No CSD	Weak activation, limited proliferation and persistence; low clinical efficacy	None	None
2nd	ISD + 1 CSD (e.g., CD28 or 4-1BB)	Enhanced activation, cytokine release, persistence, and clinical efficacy. Limited long-term persistence	ELIANA: NCT01029366, NCT02435849[31]; (Kymirah), Zuma-1: NCT02348216	All 7 FDA-approved CAR-T therapies
3rd	ISD + 2 CSD (e.g., CD28 and 4-1BB)	Mixed results; no clear benefit over 2nd-gen; increased risk of severe CRS	HD-CAR-1 trial: (NCT03676504), ENABLE-1: (NCT04049513)	Phase I/II, Phase I
4th	(2nd generation CAR: ISD + 1 CSD) + secondary transgene (e.g., NFAT) for cytokine secretion	Inducible cytokine expression; potential to overcome antigen loss; risk of on-target/off-tumor effects	NCT03778346; NCT03542799	Phase I, Phase I
5th	2nd Generation CAR + IL-2 membrane receptor ISD (IL2Rβ here)	Integrates ISD, CSD, and cytokine signaling; monovalent design limits antigen coverage	NCT05665062; NCT05666635	Early Phase I, early Phase I,

¹Trials are listed with ClinicalTrials.gov identifier.

ISD: Intracellular signaling domain; CSD: Costimulatory domain; CRS: Cytokine release syndrome; CAR: Chimeric antigen receptor; FDA: United States Food and Drug Administration; NFAT: Nuclear factor of activated T cells.

Table 3 Summary of approved chimeric antigen receptor T therapy: Manufacturers, targets, indications, and approvals[76,77]

Product name (generic name)	Manufacturer	Target antigen	ISD	CSD	Vector	Indications	Pivotal clinical trials	Regulatory approval
Kymriah (Tisagenlecleucel)	Novartis Pharmaceuticals Corporation	CD-19	CD3ζ	4-1BB	Lentiviral	B-ALL, LBCL, HGBCL, FL	NCT01626495, ENSIGN (NCT02228096), ELIANA (NCT02435849)	FDA: August 30, 2017; EMA: August 23, 2018
Yescarta (Axicabtagene ciloleucel)	Kite Pharma, Inc.	CD-19	CD3ζ	CD28	γ-retroviral	PMBCL, LBCL, HGBCL, FL	ZUMA-1 (NCT02348216), ZUMA-5 (NCT03105336), ZUMA-7 (NCT03391466), ZUMA-23 (NCT05371093)	FDA: October 18, 2017; EMA: August 23, 2018
Tecartus (Brexucabtagene autoleucel)	Kite Pharma, Inc.	CD-19	CD3ζ	CD28	γ-retroviral	MCL, B-ALL (FDA only)	ZUMA-2 (NCT02601313), ZUMA-3 (NCT02614066)	FDA: Jul 24, 2020; EMA: December 14, 2020
Breyanzi (Lisocabtagene maraleucel)	Juno Therapeutics, Inc.	CD-19	CD3ζ	4-1BB	Lentiviral	FL3B, LBCL, HGBCL, PMBCL	TRANSCEND NHL 001 (NCT02631044), TRANSCEND CLL 004 (NCT03331198), TRANSCEND FL (NCT04245839)	FDA: February 5, 2021; EMA: April 4, 2022
Abecma (Idecabtagene vicleucel)	Celgene Corporation	BCMA	CD3ζ	4-1BB	Lentiviral	MM	KarMMA (NCT03361748), KarMMA-2 (NCT03601078), KarMMA-3 (NCT03651128)	FDA: March 26, 2021; EMA: August 18, 2021
Carvykti (Ciltacabtagene autoleucel)	Johnson & Johnson Innovative Medicine	BCMA	CD3ζ	4-1BB	Lentiviral	MM	CARTITUDE-1 (NCT03548207), CARTITUDE-2 (NCT04133636), CARTITUDE-4 (NCT04181827)	FDA: February 28, 2022; EMA: May 25, 2022
Aucatzyl (Obecabtagene autoleucel)	Autolus Inc.	CD19	CD3ζ	4-1BB	Lentiviral	B-ALL	FELIX (NCT04404660)	FDA: November 8, 2024

B-ALL: Acute B-cell lymphoblastic leukemia; LBCL: Large B-cell lymphoma; BCL: B-cell lymphoma; HGBCL: High-grade B-cell lymphoma; FL: Follicular lymphoma; PMBCL: Primary mediastinal large B-cell lymphoma; MCL: Mantle cell lymphoma; FL3B: Follicular lymphoma grade-3B; MM: Multiple myeloma; CD: Cluster of differentiation; FDA: United States Food and Drug Administration; EMA: European Medicines Agency; ISD: Intracellular signaling domain; CSD: Costimulatory domains; BCMA: B-cell maturation antigen.

Table 4 Emerging target antigens for chimeric antigen receptor T cell therapy

Target specific CAR-T	Targeted cancer	Prominent clinical trials	Trial phase	Study outcome	Ref.
Hematologic cancers
CD20-CAR	Leukemias and lymphomas (e.g., R/R B-NHL)	NCT03277729, NCT04007029, NCT04697940, NCT01735604	Phase 1/2	NCT03277729: High CR+, ORR+ and safety profile; NCT01735604: 54.55% CR+, 18.18% SD+, 180 days median PFS	[88]
CD22-CAR	Leukemias and lymphomas (e.g., R/R B-ALL)	NCT03262298, NCT05470777, NCT055078227, NCT04088890	Phase 1/2	NCT03262298: Dose-reliant anti-tumor effect; NCT04088890: 100% CR+ effect in CD19-treated recurrence	[89]
CD30-CAR	R/R Hodgkin’s lymphoma	NCT02690545, NCT02917083	Phase 1/2	59% CR+; 72% ORR; high safety profile	[90]
NKG2D-Ligand based CAR	R/R- (TLL, AML, MDS)	NCT02203825	Phase 1	High antitumor efficacy	[91]
CD33-CAR	R/R AML	NCT03971799	Phase 1/2	Not completed	[92]
CD123-CAR	R/R AML	NCT04014881	Phase 1	Not completed	[92]
CLL-1.CD33 and/or, CD123-CAR	R/R AML	NCT04010877	Phase 1/2	Not completed	[92]
FLT3-CAR	R/R AML	NCT05023707	Phase 1/2	Strong anti-tumor effect and low OT/OT toxicity	[93]
IL-1RAP-CAR	CML	NCT02842320	Phase 1	Anti-leukemic cytotoxicity against antigen expressing cells	[94]
CD7-CAR	R/R TLL	NCT04689659	Phase 1/2	Effective in vivo CAR-T cell expansion, High CR+, feasible safety profile	[95]
CD4-CAR	R/R T-cell lymphoma	NCT04712864	Phase 1	Powerful anti-tumor cytotoxicity	[96]
CD38-CAR	R/R AML	NCT04351022	Phase 1/2	66.7% CR+, 240 days OS	[97]
CD5-CAR	R/R T-cell lymphoma	NCT03081910	Phase 1	Moderate response and safety profile	[98]
Solid cancers
HER2-CAR	CNS tumor	NCT03500991	Phase 1	Specially localized immune response	[99]
HER2-CAR	HER2+ breast, gastric, pancreatic cancer	NCT04650451, NCT04430595	Phase 1/2	NCT01935843: 4.5 month of PR+, 45.45% SD+, 146 days median PFS+	[100]
Allogenic NKG2D-CAR (CYAD-101)	mCRC	NCT03692429, NCT04991948	Phase 1	NCT03692429: 13.33% CR+, 60% SD, 46.67% with quarterly SD and 119 days median PFS	[101]
IL13Rα2-CAR	Glioblastoma	NCT04003649, NCT04661384, NCT02208362, NCT01935843	Phase 1	NCT01935843: Tumor shrinkage maintenance for 7.49 months; but antigen downgrading based tumor re-occurrence	[29]
GPC3-CAR	HCC	NCT03198546, NCT02395250, NCT03146234	Phase 1/2	NCT02395250 and NCT03146234: 18.18% PR+, highest 3.68 years OS+, 50.3% and 10.5% OS+ rate in 6 and 36 months	[85]
EGFR806-CAR	Advanced solid tumors	NCT03618381	Phase 1	Not completed	[92]
MUC1/PD-1-CAR	NSCLC	NCT03525782	Phase 1/2	Not completed	[92]
GD2-CAR	Brain cancer	NCT04099797	Phase 1	Enrolling participants	[92]
Mesothelin-CAR	Lung, pancreatic, ovarian, and cervical cancer	NCT01583686	Phase 1/2	Enrolling participants	[92]
CEA-CAR	Lung, colorectal, breast, stomach, and pancreatic cancer	NCT02349724	Phase 1	Enrolling participants	[92]
CD19.B7H3-CAR	Advanced solid tumors	NCT04483778	Phase 1	Enrolling participants	[92]
TnMUC1-CAR	R/R solid tumors	NCT04025216	Phase 1	Not completed	[92]

ALL: Acute lymphoblastic leukemia; AML: Acute myeloid leukemia; B-NHL: B-cell non-Hodgkin’s lymphoma; TLL: T-cell acute lymphocytic leukemia; AML: Acute myeloid leukemia; OT/OT: On-target/off-tumor; MDS: Myelodysplastic syndrome; AML: Acute myeloid leukemia; CML: Chronic myelogenous leukemia; CNS: Central nervous system; HER2: Human epidermal growth factor receptor 2; mCRC: Metastatic colorectal cancer; CR: Complete remission; CNS: Central nervous system; HCC: Hepatocellular carcinoma; NSCLC: Non-small cell lung cancer; ORR: Overall response rate; OS: Overall survival; PR: Partial response; PFS: Progression-free survival; R/R: Relapsed/refractory; SCLC: Small-cell lung cancer; SD: Stable disease; MUC1: Mucin-1; CAR: Chimeric antigen receptor.