Efficacy Of Adoptive Cell Therapy Research Articles

Efficient Capture and Traceless Release of Functional CD8+ T Cells with a Microfluidic Chip for Enhanced In Vitro and In Vivo CD4-CAR Transduction.

The chimeric antigen receptor (CAR) T cells targeting CD4 expressed cells in acute lymphoblastic leukemia (T-ALL) and acute myeloid leukemia (AML) could reduce the risk of off target effects in normal tissues. However, the efficacy of adoptive cell therapy is predominantly attributed to CD8+ T cells, necessitating their purification before lentivirus transfection to enhance the production of CD4-CAR-T cells. In this study, we developed a microfluidic chip functionalized with an optimized CD8 aptamer, A3t-MU, to facilitate the enrichment and purification of CD8+ T cells. The presented chip showed efficient capture and seamless release of CD8+ T cells from cultured T cells and peripheral blood mononuclear cells (PBMCs). The purity of the released CD8+ T cells reached 98.1%, representing a 13% improvement over the conventional magnetic bead separation method. CD4-CAR was efficiently transduced into the purified CD8+ T cells to construct CAR-T cells. We evaluated the antitumor capability of the CD4-CAR transduced CD8+ T cells (anti-CD4 CD8-CAR T cells) both in vitro and in vivo. The anti-CD4 CD8-CAR T cells exhibited significant cancer-cell-killing capacity across multiple tumor cell lines, including CEM, Jurkat, and MV4-11. Meanwhile, anti-CD4 CD8-CAR T cells significantly inhibited tumor growth in vivo. In conclusion, the presented microfluidic chip offers a cost-effective and high-purity approach for CD8+ T cell separation, enhancing CD4-CAR transduction and achieving efficient antitumor capability both in vitro and in vivo.

Empowering γδ T-cell functionality with vitamin C.

Vitamin C (ascorbic acid) is a potent antioxidant and a cofactor for various enzymes including histone demethylases and methylcytosine dioxygenases. Vitamin C also exerts direct cytotoxicity toward selected tumor cells including colorectal carcinoma. Moreover, vitamin C has been shown to impact immune cell differentiation at various levels including maturation and/or functionality of T cells and their progenitors, dendritic cells, B cells, and NK cells. γδ T cells have recently attracted great interest as effector cells for cell-based cancer immunotherapy, due to their HLA-independent recognition of a large variety of tumor cells. While γδ T cells can thus be also applied as an allogeneic off-the-shelf product, it is obvious that the effector function of γδ T cells needs to be optimized to ensure the best possible clinical efficacy. Here we review the immunomodulatory mechanisms of vitamin C with a special focus on how vitamin C enhances the effector function of γδ T cells. We also discuss future directions of how vitamin C can be used in the clinical setting to boost the efficacy of adoptive cell therapies.

Female Sex Effect on Anti-CD19 CART Cell Therapy for Relapsed/Refractory B-Cell Lymphoma: A Grupo Español De Trasplante y Terapia Celular (GETH-TC) Study

Introduction Recent studies have shown the potential implication of sexual disparity on the immune system, emphasizing the significant roles of androgens and estrogens in immune cell function and their potential implications for immune responses and antitumor immunity. Anti-CD19 CART therapy is a new immunotherapy pillar for patients with relapsed/refractory large B-cell lymphoma (R/R LBCL). However, this treatment has major limitations, including high individual variability with life-threatening toxicities, antigen escape, poor tumor infiltration, T cell exhaustion, and an immunosuppressive microenvironment. The underlying mechanisms responsible for these issues remain unknown and may potentially involve sex-based differences. To date, no studies addressed sex differences in CART therapy. Methods Data from consecutive patients with R/R LBCL from the Grupo Español de Trasplante y Terapia Celular (GETH-TC) who received commercial anti-CD19 CART infusion between November 2018 and December 2022 were retrospectively collected from electronic medical records at 12 Spanish institutions. Patients were divided by sex into two groups for analysis and stratified by patient/disease characteristics and CART cell product. A t-test comparison between the two cohorts was performed. The primary endpoint was comparing 1-year progression-free survival (1y-PFS) between the groups. Secondary endpoints were overall survival (OS), relapse incidence/progression of disease (RI/POD), non-relapse mortality (NRM), cytokine release syndrome (CRS) and immune-effector cells associated neurotoxicity (ICANS) cumulative incidence. Patient sex variable was added into the Cox Proportional-Hazards model for a multivariate analysis for each endpoint in addition to all the variables which were statistically significant in univariate analysis (α=0.05). Results A total of 479 patients received anti-CD19 CART infusion. Among them, 185 patients (39%) were female and 294 patients (61%) were male. No statistically significant differences were found in patient, disease and CART characteristics between the two cohorts ( Table 1). At 1-year post-infusion, PFS and OS were 39% (95% confidence interval [CI]: 34-44%) and 57% (95% CI: 51-62%), respectively. ( Fig. 1). On multivariate analysis, female sex had a favorable impact on 1-year PFS (HR=1.33; 95% CI: 1.01-1.75, p=0.04) but not on OS. A subset analysis on females revealed no significant differences in outcomes based on pre and postmenopausal age (p=0.23), with a fixed cut-off at 50 years. The 1 year RI/POD and NRM rates were 56% (95% CI: 52-60%) and 5% (95% CI:3-7%), respectively. Female sex was significantly associated with a lower RI/POD at one year (HR=0.68; 95% CI:1.10-1.96, p=0.01) but not with NRM. Regarding safety, the 1-month cumulative incidences of CRS grade ≥2 and ≥3 were 47% (95% CI: 41-53%) and 11% (95% CI:7-15%), respectively, without statistically significant correlation to female sex in univariate and multivariate analysis. However, the 1-month cumulative occurrence of ICANS grade ≥2 (28%, 95% CI: 26%-30%) and ≥3 (16%, 95% CI: 14%-18%) were significantly associated with female sex in univariate analysis (p<0.01 and p=0.02, respectively), with a trend towards significance in multivariate analysis (HR=1.4; 95% CI: 0.99-1.2, p=0.06 and HR=1.48; 95% CI:0.90-2.44, p=0.12). Conclusions In this retrospective analysis we compared for the first time the clinical outcomes of female and male patients who received anti-CD19 CARTs for R/R LBCL. Our findings suggest that, in a real-world setting, female sex is linked to improved survival outcomes, lower relapse rates, and a tendency toward higher neurotoxicity. This observation, without disparities in female outcomes based on pre and postmenopausal age, could suggest that such effect is potentially related to androgens and not to estrogens-dependent mechanisms on T cells. Sex differences, possibly related to hormonal mechanisms, should be further investigated to discover newer therapeutic mechanisms to increase the efficacy of adoptive cell therapies.

Targeting myeloid-derived suppressor cells with gemcitabine to enhance efficacy of adoptive cell therapy in bladder cancer.

New therapeutics in development for bladder cancer need to address the recalcitrant nature of the disease. Intravesical adoptive cell therapy (ACT) with tumor infiltrating lymphocytes (TIL) can potentially induce durable responses in bladder cancer while maximizing T cells at the tumor site. T cells infused into the bladder directly encounter immunosuppressive populations, such as myeloid derived suppressor cells (MDSCs), that can attenuate T cell responses. Intravesical instillation of gemcitabine can be used as a lymphodepleting agent to precondition the bladder microenvironment for infused T cell products. Urine samples from bladder cancer patients and healthy donors were analyzed by flow cytometry and cytometric bead array for immune profiling and cytokine quantification. MDSCs were isolated from the urine and cocultured with stimulated T cells to assess effects on proliferation. An orthotopic murine model of bladder cancer was established using the MB49-OVA cell line and immune profiling was performed. MDSCs from tumor-bearing mice were cocultured with OT-I splenocytes to assess T cell proliferation. Mice received intravesical instillation of gemcitabine and depletion of immune cells was measured via flow cytometry. Bladder tumor growth of mice treated with intravesical gemcitabine, OT-I transgenic T cells, or combination was monitored via ultrasound measurement. In comparison to healthy donors, urine specimen from bladder cancer patients show high levels of MDSCs and cytokines associated with myeloid chemotaxis, T cell chemotaxis, and inflammation. T cells isolated from healthy donors were less proliferative when cocultured with MDSCs from the urine. Orthotopic murine bladder tumors also presented with high levels of MDSCs along with enrichment of cytokines found in the patient urine samples. MDSCs isolated from spleens of tumor-bearing mice exerted suppressive effects on the proliferation of OT-I T cells. Intravesical instillation of gemcitabine reduced overall immune cells, MDSCs, and T cells in orthotopic bladder tumors. Combination treatment with gemcitabine and OT-I T cells resulted in sustained anti-tumor responses in comparison to monotherapy treatments. MDSCs are enriched within the microenvironment of bladder tumors and are suppressive to T cells. Gemcitabine can be used to lymphodeplete bladder tumors and precondition the microenvironment for intravesical ACT.

Ginsenoside Rg1 improves anti-tumor efficacy of adoptive cell therapy by enhancing T cell effector functions.

Adoptive cell therapy (ACT) has emerged with remarkable efficacies for tumor immunotherapy. Chimeric antigen receptor (CAR) T cell therapy, as one of most promising ACTs, has achieved prominent effects in treating malignant hematological tumors. However, the insufficient killing activity and limited persistence of T cells in the immunosuppressive tumor microenvironment limit the further application of ACTs for cancer patients. Many studies have focused on improving cytotoxicity and persistence of T cells to achieve improved therapeutic effects. In this study, we explored the potential function in ACT of ginsenoside Rg1, the main pharmacologically active component of ginseng. We introduced Rg1 during the in vitro activation and expansion phase of T cells, and found that Rg1 treatment upregulated two T cell activation markers, CD69 and CD25, while promoting T cell differentiation towards a mature state. Transcriptome sequencing revealed that Rg1 influenced T cell metabolic reprogramming by strengthening mitochondrial biosynthesis. When co-cultured with tumor cells, Rg1-treated T cells showed stronger cytotoxicity than untreated cells. Moreover, adding Rg1 to the culture endowed CAR-T cells with enhanced anti-tumor efficacy. This study suggests that ginsenoside Rg1 provides a potential approach for improving the anti-tumor efficacy of ACT by enhancing T cell effector functions.

Effect of autologous lymphocytes combined with chemotherapy as the first-line treatment of advanced gastric cancer.

4037 Background: To evaluate the safety and initial efficacy of adoptive cell therapy (ACT) combined with SOX in first-line treatment of locally advanced unresectable or metastatic gastric adenocarcinoma/gastroesophageal adenocarcinoma. Methods: In this single-arm, single-center exploratory trial, patients with histologically confirmed locally advanced unresectable or metastatic gastric adenocarcinoma/gastroesophageal adenocarcinoma were randomly assigned (1:1) to receive ACT in combination with S-1 and oxaliplatin (SOX) or SOX alone. The primary endpoint was the incidence of adverse events (AEs). Secondary endpoints were progression-free survival (PFS), overall survival (OS), objective response rate (ORR), and disease control rate (DCR). Results: Fifty-nine patients were enrolled in the study between November 20, 2014 and September 6, 2017. 31 patients received ACT combined with SOX (ACT-SOX) and 28 patients received SOX. The most common AEs in both groups were gastrointestinal reaction, leucopenia, neutropenia, anemia, thrombocytopenia, hyperbilirubinemia and elevated aspartate transaminase concentration, with a higher incidence in the SOX group. The median PFS for ACT-SOX and SOX were 6.9 and 4.9 months respectively (HR 0.80, p=0.45), and the median OS were 17.8 and 9.75 months (HR 0.76, p=0.34). Patients who received more than three injections of specific lymphocyte subsets benefited the most from combination therapy. Cox univariate and multivariate analysis showed that tumor metastasis to more than two organs was the main risk factor for PFS and OS. 29 patients in the ACT-SOX group and 25 in the SOX group had measurable lesions. The ORR of ACT-SOX group and SOX group was 55.2% and 32.0%, and DCR of two groups was 93.1% and 88.0%. Conclusions: The safety of ACT-SOX in first-line treatment of patients with locally advanced unresectable or metastatic gastric adenocarcinoma/gastroesophageal adenocarcinoma is good. Compared with SOX alone, although the PFS and OS of ACT-SOX did not reach statistical difference, it could further extend the time of PFS and OS, and the absolute improvement time of OS was about 8.05 months. Continuous benefit of ACT-SOX was observed through long-term follow-up. Clinical trial information: NCT02504229 .

Enhancement of T cell infiltration via tumor-targeted Th9 cell delivery improves the efficacy of antitumor immunotherapy of solid tumors

Insufficient infiltration of T cells severely compromises the antitumor efficacy of adoptive cell therapy (ACT) against solid tumors. Here, we present a facile immune cell surface engineering strategy aiming to substantially enhance the anti-tumor efficacy of Th9-mediated ACT by rapidly identifying tumor-specific binding ligands and improving the infiltration of infused cells into solid tumors. Non-genetic decoration of Th9 cells with tumor-targeting peptide screened from phage display not only allowed precise targeted ACT against highly heterogeneous solid tumors but also substantially enhanced infiltration of CD8+ T cells, which led to improved antitumor outcomes. Mechanistically, infusion of Th9 cells modified with tumor-specific binding ligands facilitated the enhanced distribution of tumor-killing cells and remodeled the immunosuppressive microenvironment of solid tumors via IL-9 mediated immunomodulation. Overall, we presented a simple, cost-effective, and cell-friendly strategy to enhance the efficacy of ACT against solid tumors with the potential to complement the current ACT.

Novel Fas-TNFR chimeras that prevent Fas ligand-mediated kill and signal synergistically to enhance CAR T cell efficacy

The hostile tumor microenvironment limits the efficacy of adoptive cell therapies. Activation of the Fas death receptor initiates apoptosis and disrupting these receptors could be key to increasing CAR Tcell efficacy. We screened a library of Fas-TNFR proteins identifying several novel chimeras that not only prevented Fas ligand-mediated kill, but also enhanced CAR Tcell efficacy by signaling synergistically with the CAR. Upon binding Fas ligand, Fas-CD40 activated the NF-κB pathway, inducing greatest proliferation and IFN-γ release out of all Fas-TNFRs tested. Fas-CD40 induced profound transcriptional modifications, particularly genes relating to the cell cycle, metabolism, and chemokine signaling. Co-expression of Fas-CD40 with either 4-1BB- or CD28-containing CARs increased invitro efficacy by augmenting CAR Tcell proliferation and cancer target cytotoxicity, and enhanced tumor killing and overall mouse survival invivo. Functional activity of the Fas-TNFRs were dependent on the co-stimulatory domain within the CAR, highlighting crosstalk between signaling pathways. Furthermore, we show that a major source for Fas-TNFR activation derives from CAR Tcells themselves via activation-induced Fas ligand upregulation, highlighting a universal role of Fas-TNFRs in augmenting CAR Tcell responses. We have identified Fas-CD40 as the optimal chimera for overcoming Fas ligand-mediated kill and enhancing CAR Tcell efficacy.

CTLs, NK cells and NK-derived EVs against breast cancer

Patients with advanced stage breast cancer need novel therapies. New potential treatments have been developed, such as adoptive cellular therapies and alternative cell-free immunotherapies. The goal of this study was to assess the cytotoxicity of three of the patient-derived immune components, CTLs, NK cells and NK-derived EVs, and evaluate the potential for the development of novel therapy against breast cancer. CTLs were activated against MUC-1 antigen. The in vitro cytotoxic activity of three components was assessed with flow cytometry and in vivo study revealed the efficacy of adoptive cell therapy. Overall, CTLs exhibited the highest cytotoxicity against spheroids of MCF7 breast adenocarcinoma, reaching in all cases higher than double the percentage of NK cells’ cytotoxicity. NK-derived EVs exhibited the lowest effect against MCF7 spheroids comparing to the two cell populations. MUC-1 specific CTLs were evaluated with adoptive cell therapy mice study and appeared to be well tolerable and moderately efficacious. More studies need to be performed with CTLs to evaluate safety and efficacy in order to assess their clinical potential, while NK cells and NK-derived EVs are promising candidates that require more experiments to enhance their cytotoxicity.

11P WU-NK-101: An enhanced NK cell therapy optimized for function in the tumor microenvironment (TME)

The efficacy of adoptive cell therapies against solid tumors has been limited by the immune-suppressive TME, which aids immune escape. WU-NK-101, manufactured using the MONETATM platform, is an NK product derived from healthy donor NK cells that addresses challenges of adoptive cell therapy in the setting of an adverse TME.

Enhancing adoptive T cell therapy for solid tumor with cell-surface anchored immune checkpoint inhibitor nanogels

The efficacy of Adoptive Cell Therapy (ACT) for solid tumor is still mediocre. This is mainly because tumor cells can hijack ACT T cells' immune checkpoint pathways to exert immunosuppression in the tumor microenvironment. Immune Checkpoint Inhibitors such as anti-PD-1 (aPD1) can counter the immunosuppression, but the synergizing effects of aPD1 to ACT was still not satisfactory. Here we demonstrate an approach to safely anchor aPD1-formed nanogels onto T cell surface via bio-orthogonal click chemistry before adoptive transfer. The spatial-temporal co-existence of aPD1 with ACT T cells and the responsive drug release significantly improved the treatment outcome of ACT in murine solid tumor model. The average tumor weight of the group treated by cell-surface anchored aPD1 was only 18 % of the group treated by equivalent dose of free aPD1 and T cells. The technology can be broadly applicable in ACTs employing natural or Chimeric Antigen Receptor (CAR) T cells.

Targeting of Nrf2 improves antitumoral responses by human NK cells, TIL and CAR T cells during oxidative stress

BackgroundAdoptive cell therapy using cytotoxic lymphocytes is an efficient immunotherapy against solid and hematological cancers. However, elevated levels of reactive oxygen species (ROS) in the hostile tumor microenvironment can impair...

P38 inhibition enhances TCR-T cell function and antagonizes the immunosuppressive activity of TGF-β

The efficacy of adoptive cell therapy (ACT) relies on the abilities of T cells in self-expansion, survival and the secretion of effector molecules. Here, we presented an optimized method to generate T cells with improved functions by supplementing the culture medium with p38 inhibitor and the combination of IL-7 and IL-15 or IL-2 alone. The addition of p38 inhibitor, Doramapimod or SB202190, to IL-7 and IL-15 culture largely increased the capacity of T cells in the proliferation with enrichment of the naïve-like subsets and expression of CD62L. Importantly, we found this regimen has generated complete T cell resistance to TGF-β-induced functional suppression, with sustained levels of the IFN-γ and Granzyme-B productions. Such findings were also validated in the melanoma-associated antigen recognized by T cells (MART-1) specific T cell receptor (TCR) engineered T cells, which were expanded in Doramapimod and IL-7 + IL-15 added media. In conclusion, we have established and optimized a protocol with the combination of p38 inhibitor, IL-7 and IL-15, rather than IL-2, for the generation of functionally enhanced T cells applicable for ACT.

T cells armed with C-X-C chemokine receptor type 6 enhance adoptive cell therapy for pancreatic tumours.

The efficacy of adoptive cell therapy for solid tumours is hampered by the poor accumulation of the transferred T cells in tumour tissue. Here, we show that the forced expression of the C-X-C chemokine receptor type 6 (CXCR6, whose ligand is highly expressed by human and murine pancreatic cancer cells and by tumour-infiltrating immune cells) in antigen-specific T cells enhanced the recognition and lysis of pancreatic cancer cells and the efficacy of adoptive cell therapy for pancreatic cancer. In mice with subcutaneous pancreatic tumours treated with T cells with either a transgenic T-cell receptor or a murine chimeric antigen receptor targeting the tumour-associated antigen epithelial cell-adhesion molecule, and in mice with orthotopic pancreatic tumours or patient-derived xenografts treated with T cells expressing a chimeric antigen receptor targeting mesothelin, the T cells exhibited enhanced intratumoral accumulation, exerted sustained antitumoral activity and prolonged animal survival only when co-expressing CXCR6. Arming tumour-specific T cells with tumour-specific chemokine receptors may represent a promising strategy for the realization of adoptive cell therapy for solid tumours.

Bromodomain protein BRD4 directs CD8 T cell differentiation during infection and cancer

Abstract In response to infection and malignancy, antigen-specific CD8 T cells differentiate into functionally diverse populations that are critical for resolving disease and providing durable immunity. Here, we utilized an in vivo RNAi screening strategy to identify transcriptional and epigenetic regulators controlling CD8 T cell fate. Through small-molecule inhibition, RNAi studies, and induced genetic deletion, we revealed an essential role for the chromatin modifier and BET family member BRD4 in supporting T cell differentiation during infection and cancer. BRD4 was found to bind diverse regulatory regions critical to effector T cell differentiation and was essential for transcriptional activity of terminal effector-specific super-enhancers in vivo. Consequentially, induced deletion or chemical inhibition of BRD4 resulted in impaired maintenance of a terminal effector phenotype. In preclinical models of cancer, BRD4 was also required for formation of a terminally differentiated CD8 T cell state in the tumor microenvironment, which we show holds implications for immunotherapies. Tailored inhibition of BRD4 enhanced immune checkpoint blockade efficacy; however, complete ablation of BRD4 activity blunted T cell effector function and adoptive cell therapy efficacy. Taken together, these data reveal an unappreciated requirement for BRD4 in coordinating activity of cis-regulatory elements to control CD8 T cell fate and stability of lineage identity, and provide insight for understanding the efficacy and full therapeutic potential of BET inhibition and T cell immunotherapies.

CD5 levels define functionally heterogeneous populations of naïve human CD4+ T cells.

Studies in murine models show that subthreshold TCR interactions with self‐peptide are required for thymic development and peripheral survival of naïve T cells. Recently, differences in the strength of tonic TCR interactions with self‐peptide, as read‐out by cell surface levels of CD5, were associated with distinct effector potentials among sorted populations of T cells in mice. However, whether CD5 can also be used to parse functional heterogeneity among human T cells is less clear. Our study demonstrates that CD5 levels correlate with TCR signal strength in human naïve CD4+ T cells. Further, we describe a relationship between CD5 levels on naïve human CD4+ T cells and binding affinity to foreign peptide, in addition to a predominance of CD5hi T cells in the memory compartment. Differences in gene expression and biases in cytokine production potential between CD5lo and CD5hi naïve human CD4+ T cells are consistent with observations in mice. Together, these data validate the use of CD5 surface levels as a marker of heterogeneity among human naïve CD4+ T cells with important implications for the identification of functionally biased T‐ cell populations that can be exploited to improve the efficacy of adoptive cell therapies.

Phase I/II study protocol to assess safety and efficacy of adoptive cell therapy with anti-PD-1 plus low-dose pegylated-interferon-alpha in patients with metastatic melanoma refractory to standard of care treatments: the ACTME trial

IntroductionTreatment with anti-PD-1 immunotherapy does not lead to long-lasting clinical responses in approximately 60% of patients with metastatic melanoma. These refractory patients, however, can still respond to treatment with tumour...

Intuitive CD8+ T cells sense DNA

Cancer Stimulator of interferon genes (STING) agonism is an area of active exploration for cancer immunotherapy. Li et al. examined a DNA-sensing cascade called cGAS-STING in antitumor CD8+ T cells. They observed dampened STING activity in CD8+ T cells from patients with cancer or mice implanted with tumors. By contrast, STING signaling in transferred T cells supported a stem-like memory phenotype, which is known to be beneficial for responses to immunotherapy. Cytosolic DNA was enriched in activated T cells, and STING agonism improved the efficacy of adoptive cell therapy in multiple mouse models. These results highlight that CD8+ T cell DNA sensing could be exploited for therapeutic benefit in immunotherapy. Sci. Transl. Med. 12 , eaay9013 (2020).

Exploiting Human NK Cells in Tumor Therapy.

NK cells play an important role in the innate defenses against tumor growth and metastases. Human NK cell activation and function are regulated by an array of HLA class I-specific inhibitory receptors and activating receptors recognizing ligands expressed de novo on tumor or virus-infected cells. NK cells have been exploited in immunotherapy of cancer, including: (1) the in vivo infusion of IL-2 or IL-15, cytokines inducing activation and proliferation of NK cells that are frequently impaired in cancer patients. Nonetheless, the significant toxicity experienced, primarily with IL-2, limited their use except for combination therapies, e.g., IL-15 with checkpoint inhibitors; (2) the adoptive immunotherapy with cytokine-induced NK cells had effect on some melanoma metastases (lung), while other localizations were not affected; (3) a remarkable evolution of adoptive cell therapy is represented by NK cells engineered with CAR-targeting tumor antigens (CAR-NK). CAR-NK cells complement CAR-T cells as they do not cause GvHD and may be obtained from unrelated donors. Accordingly, CAR-NK cells may represent an “off-the-shelf” tool, readily available for effective tumor therapy; (4) the efficacy of adoptive cell therapy in cancer is also witnessed by the αβT cell- and B cell-depleted haploidentical HSC transplantation in which the infusion of donor NK cells and γδT cells, together with HSC, sharply reduces leukemia relapses and infections; (5) a true revolution in tumor therapy is the use of mAbs targeting checkpoint inhibitors including PD-1, CTLA-4, the HLA class I-specific KIR, and NKG2A. Since PD-1 is expressed not only by tumor-associated T cells but also by NK cells, its blocking might unleash NK cells playing a crucial effector role against HLA class I-deficient tumors that are undetectable by T cells.

Pathogen-Boosted Adoptive Cell Transfer Therapy Induces Endogenous Antitumor Immunity through Antigen Spreading.

Loss of target antigens in tumor cells has become one of the major hurdles limiting the efficacy of adoptive cell therapy (ACT)-based immunotherapies. The optimal approach to overcome this challenge includes broadening the immune response from the initially targeted tumor-associated antigen (TAA) to other TAAs expressed in the tumor. To induce a more broadly targeted antitumor response, we utilized our previously developed Re-energized ACT (ReACT), which capitalizes on the synergistic effect of pathogen-based immunotherapy and ACT. In this study, we showed that ReACT induced a sufficient endogenous CD8+ T-cell response beyond the initial target to prevent the outgrowth of antigen loss variants in a B16-F10 melanoma model. Sequentially, selective depletion experiments revealed that Batf3-driven cDC1s were essential for the activation of endogenous tumor-specific CD8+ T cells. In ReACT-treated mice that eradicated tumors, we observed that endogenous CD8+ T cells differentiated into memory cells and facilitated the rejection of local and distal tumor rechallenge. By targeting one TAA with ReACT, we provided broader TAA coverage to counter antigen escape and generate a durable memory response against local relapse and metastasis.See related Spotlight on p. 2.