Adoptive neoantigen-reactive T cell therapy: improvement strategies and current clinical researches

Abstract

Neoantigens generated by non-synonymous mutations of tumor genes can induce activation of neoantigen-reactive T (NRT) cells which have the ability to resist the growth of tumors expressing specific neoantigens. Immunotherapy based on NRT cells has made preeminent achievements in melanoma and other solid tumors. The process of manufacturing NRT cells includes identification of neoantigens, preparation of neoantigen expression vectors or peptides, induction and activation of NRT cells, and analysis of functions and phenotypes. Numerous improvement strategies have been proposed to enhance the potency of NRT cells by engineering TCR, promoting infiltration of T cells and overcoming immunosuppressive factors in the tumor microenvironment. In this review, we outline the improvement of the preparation and the function assessment of NRT cells, and discuss the current status of clinical trials related to NRT cell immunotherapy.

Keywords: Adoptive cell therapy; Cancer; Immunotherapy; Neoantigen-reactive T cell.

Fig. 1

Process of NRT cell manufacturing and adoptive therapy. NRT cells are manufactured via the following steps: A acquisition and cultivation of tumor specimens and peripheral blood mononuclear cells; B mutation identification with WES/WGS/RNA sequencing (seq), potential antigen detection with mass spectrometry; C neoantigen prediction; D design and synthesis of neoantigen-encoding mRNA in tandem minigene configuration or neoantigen peptides; E pulsing DCs directly with peptides, or transfection of neoantigen-encoding mRNA into DCs by electroporation, followed by the co-incubation of neoantigen-loaded DCs and PBMC-derived T cells, F flow cytometry-based neoantigen-specific T cell sorting; G rapid expansion protocol (REP) of NRT cells, H reinfusion of NRT cells into patients or mouse model

Fig. 2

Feasible improvement for the manufacture of NRT cells. A Optimize neoantigen predicting platforms to promote the efficiency and accuracy of prediction. B Micro-electroporation (a), microinjection (b) and nano-delivery c can be applied to elevate transfection efficiency. Artificial APCs can be used to increase the efficiency of antigen presentation. C Promote NRT cell expansion in rapid expanding protocol (REP) through adding cytokines (IL-2, IL-7 and IL-15) (a) or anti-4-1BB antibody (b), using feeder cells (Bcl-xL, K562) (c), inhibiting AICD signaling cascade (d), or adopting the culture method of “young” T cells (e) or organoids (f). D Screen NRT cells with surface or genetic markers via single-cell transcriptome and TCR sequencing

Fig. 3

Feasible strategies for the improvement of T cell antitumor function. A Engineer T cell signals. Signal 1: edit TCR genes or make TCR and CD8 αβ co-expression. Signal 2: join CD28 to CD3ζ combined with 4-1BB or OX40 to enhance activation signals, construct the chimeric switch receptor (e. g., CD28 linked to PD-1,CTLA-4 and TIGHT) to reverse inhibitory signals. Signal 3: modify cytokine receptors (e. g., IL-2 orthogonal receptor) and increase the expression of autologous or heterologous cytokines or chemokines. B Produce multiple-function T cells: optimize CARs, secrete cytokines and enzymes, release extracellular vesicles containing RNAs, express multiple chemokine receptors, and modify immunosuppressive signal receptors. C Universal strategies to restore and increase the expression of MHC (inducing IFNγ production, using epigenetic silence or autophagy inhibitors (a)) and MICA/B (anti-MICA/B antibody (b))

Fig. 4

Strategies for promoting NRT cell tumor infiltration and modifying suppressive TME. A Improve tumor reactive T cell infiltration through inhibiting immunosuppressive signals, and promoting the expression of chemokines and the release of tumor specific antigens. B Eliminate the physical barrier effect of extracellular matrix(ECM) using drugs such as nab-paclitaxel. C Normalize abnormal vasculature by using VEGFR inhibitor. D Deplete immunosuppressive cells(Treg and MDSCs) and inhibit their activation signals. E Repolarize tumor-associated macrophages(TAM) from M2 towards M1. F Induce the formation of tertiary lymphoid structures(TLSs)(chemotherapy, ICIs, vaccine and stromal cell)

Fig. 5

Feasible combinational therapy strategies of adoptive NRT cell therapy. Feasible combinational therapy strategies are shown in this figure. Adoptive NRT cell therapy can be combined with such strategies: immune therapy (immune check point inhibitors (ICIs), mRNA/peptide neoantigen vaccine, DC neoantigen vaccine), targeted drugs (e.g., antiangiogenic agents) and traditional therapy (surgery, radiotherapy and chemotherapy)