Multiple Signaling Roles of CD3ε and Its Application in CAR-T Cell Therapy.

A T cell receptor (TCR) mediates antigen-induced signaling through its associated CD3ε, δ, γ, and ζ, but the contributions of different CD3 chains remain elusive. Using quantitative mass spectrometry, we simultaneously quantitated the phosphorylation of the immunoreceptor tyrosine-based activation motif (ITAM) of all CD3 chains upon TCR stimulation. A subpopulation of CD3ε ITAMs was mono-phosphorylated, owing to Lck kinase selectivity, and specifically recruited the inhibitory Csk kinase to attenuate TCR signaling, suggesting that TCR is a self-restrained signaling machinery containing both activating and inhibitory motifs. Moreover, we found that incorporation of the CD3ε cytoplasmic domain into a second-generation chimeric antigen receptor (CAR) improved antitumor activity of CAR-T cells. Mechanistically, the Csk-recruiting ITAM of CD3ε reduced CAR-T cytokine production whereas the basic residue rich sequence (BRS) of CD3ε promoted CAR-T persistence via p85 recruitment. Collectively, CD3ε is a built-in multifunctional signal tuner, and increasing CD3 diversity represents a strategy to design next-generation CAR.

Sequential CD7 CAR T-Cell Therapy and Allogeneic HSCT without GVHD Prophylaxis.

BACKGROUND: Patients with relapsed or refractory hematologic cancers have a poor prognosis. Chimeric antigen receptor (CAR) T-cell therapy as a bridge to allogeneic hematopoietic stem-cell transplantation (HSCT) has the potential for long-term tumor elimination. However, pre-HSCT myeloablation and graft-versus-host disease (GVHD) prophylaxis agents have toxic effects and could eradicate residual CAR T cells and compromise antitumor effects. Whether the integration of CAR T-cell therapy and allogeneic HSCT can preserve CAR T-cell function and improve tumor control is unclear. METHODS: We tested a novel "all-in-one" strategy consisting of sequential CD7 CAR T-cell therapy and haploidentical HSCT in 10 patients with relapsed or refractory CD7-positive leukemia or lymphoma. After CAR T-cell therapy led to complete remission with incomplete hematologic recovery, patients received haploidentical HSCT without pharmacologic myeloablation or GVHD prophylaxis drugs. Toxic effects and efficacy were closely monitored. RESULTS: After CAR T-cell therapy, all 10 patients had complete remission with incomplete hematologic recovery and grade 4 pancytopenia. After haploidentical HSCT, 1 patient died on day 13 of septic shock and encephalitis, 8 patients had full donor chimerism, and 1 patient had autologous hematopoiesis. Three patients had grade 2 HSCT-associated acute GVHD. The median follow-up was 15.1 months (range, 3.1 to 24.0) after CAR T-cell therapy. Six patients remained in minimal residual disease-negative complete remission, 2 had a relapse of CD7-negative leukemia, and 1 died of septic shock at 3.7 months. The estimated 1-year overall survival was 68% (95% confidence interval [CI], 43 to 100), and the estimated 1-year disease-free survival was 54% (95% CI, 29 to 100). CONCLUSIONS: Our findings suggest that sequential CD7 CAR T-cell therapy and haploidentical HSCT is safe and effective, with remission and serious but reversible adverse events. This strategy offers a feasible approach for patients with CD7-positive tumors who are ineligible for conventional allogeneic HSCT. (Funded by the National Natural Science Foundation of China and the Key Project of Science and Technology Department of Zhejiang Province; ClinicalTrials.gov numbers, NCT04599556 and NCT04538599.).

Exploiting Ca2+ signaling in T cells to advance cancer immunotherapy.

Decades of basic research has established the importance of Ca2+ to various T cell functions, such as cytotoxicity, proliferation, differentiation and cytokine secretion. We now have a good understanding of how proximal TCR signaling initiates Ca2+ influx and how this influx subsequently changes transcriptional activities in T cells. As chimeric antigen receptor (CAR)-T therapy has achieved great clinical success, is it possible to harness Ca2+ signaling to further advance CAR-T research? How is CAR signaling different from TCR signaling? How can functional CARs be identified in a high-throughput way? Quantification of various Ca2+ signals downstream of CAR/TCR activation might help answer these questions. Here we first summarized recent studies that used Ca2+ dye, genetically-encoded Ca2+ indicators (GECI) or transcriptional activity reporters to understand CAR activation in vitro and in vivo. We next reviewed several proof-of-concept reports that manipulate Ca2+ signaling by light or ultrasound to achieve precise spatiotemporal control of T cell functions. These efforts, though preliminary, opened up new avenues to solve the on-target/off-tumor problem of therapeutic T cells. Other modalities to regulate Ca2+ signaling, such as radio wave and electrical pulse, were also discussed. Thus, monitoring or manipulating Ca2+ signaling in T cells provides us many opportunities to advance cancer immunotherapy.

LC-MS/MS Analysis Unravels Deep Oxidation of Manganese Superoxide Dismutase in Kidney Cancer.

Manganese superoxide dismutase (MNSOD) is one of the major scavengers of reactive oxygen species (ROS) in mitochondria with pivotal regulatory role in ischemic disorders, inflammation and cancer. Here we report oxidative modification of MNSOD in human renal cell carcinoma (RCC) by the shotgun method using data-dependent liquid chromatography tandem mass spectrometry (LC-MS/MS). While 5816 and 5571 proteins were identified in cancer and adjacent tissues, respectively, 208 proteins were found to be up- or down-regulated (p < 0.05). Ontological category, interaction network and Western blotting suggested a close correlation between RCC-mediated proteins and oxidoreductases such as MNSOD. Markedly, oxidative modifications of MNSOD were identified at histidine (H54 and H55), tyrosine (Y58), tryptophan (W147, W149, W205 and W210) and asparagine (N206 and N209) residues additional to methionine. These oxidative insults were located at three hotspots near the hydrophobic pocket of the manganese binding site, of which the oxidation of Y58, W147 and W149 was up-regulated around three folds and the oxidation of H54 and H55 was detected in the cancer tissues only (p < 0.05). When normalized to MNSOD expression levels, relative MNSOD enzymatic activity was decreased in cancer tissues, suggesting impairment of MNSOD enzymatic activity in kidney cancer due to modifications. Thus, LC-MS/MS analysis revealed multiple oxidative modifications of MNSOD at different amino acid residues that might mediate the regulation of the superoxide radicals, mitochondrial ROS scavenging and MNSOD activity in kidney cancer.

Unraveling Molecular Differences of Gastric Cancer by Label-Free Quantitative Proteomics Analysis.

Gastric cancer (GC) has significant morbidity and mortality worldwide and especially in China. Its molecular pathogenesis has not been thoroughly elaborated. The acknowledged biomarkers for diagnosis, prognosis, recurrence monitoring and treatment are lacking. Proteins from matched pairs of human GC and adjacent tissues were analyzed by a coupled label-free Mass Spectrometry (MS) approach, followed by functional annotation with software analysis. Nano-LC-MS/MS, quantitative real-time polymerase chain reaction (qRT-PCR), western blot and immunohistochemistry were used to validate dysregulated proteins. One hundred forty-six dysregulated proteins with more than twofold expressions were quantified, 22 of which were first reported to be relevant with GC. Most of them were involved in cancers and gastrointestinal disease. The expression of a panel of four upregulated nucleic acid binding proteins, heterogeneous nuclear ribonucleoprotein hnRNPA2B1, hnRNPD, hnRNPL and Y-box binding protein 1 (YBX-1) were validated by Nano-LC-MS/MS, qRT-PCR, western blot and immunohistochemistry assays in ten GC patients' tissues. They were located in the keynotes of a predicted interaction network and might play important roles in abnormal cell growth. The label-free quantitative proteomic approach provides a deeper understanding and novel insight into GC-related molecular changes and possible mechanisms. It also provides some potential biomarkers for clinical diagnosis.

CRISPR/Cas-based CAR-T cells: production and application.

Chimeric antigen receptor T cell (CAR-T) therapy has revolutionized the treatment approach for cancer, autoimmune disease, and heart disease. The integration of CAR into T cells is typically facilitated by retroviral or lentiviral vectors. However, the random insertion of CARs can lead to issues like clonal expansion, oncogenic transformation, variegated transgene expression, and transcriptional silencing. The advent of precise gene editing technology, like Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR), allows for controlled and precise genome modification, facilitating the translation of CAR-T research to the clinical applications. This review aims to provide a comprehensive analysis of the application of CRISPR gene editing techniques in the context of precise deletion and insertion methodologies, with a specific focus on their potential for enhancing the development and utilization of CAR-T cell therapy.

Relapsed/Refractory Peripheral T-Cell Lymphoma-Associated Hemophagocytic Lymphohistiocytosis With UNC13D and CD27 Germline Mutations.

Hemophagocytic lymphohistiocytosis (HLH) is a severe hyperinflammatory disease characterized by familial and acquired forms. Here, we present the case of a 26-year-old male patient with relapsed/refractory peripheral T-cell lymphoma and concurrent HLH. Whole-exon sequencing revealed germline mutations associated with HLH, including those in critical genes such as CD27 and UNC13D and other germline heterozygous variants (NOTCH2, NOTCH3, IL2RA, TYK2, AGL, CFD, and F13A1). CD107a analyses consistently demonstrated impaired degranulation of cytotoxic T-lymphocytes and natural killer (NK) cells. Examination of the patient's family pedigree revealed that his father and mother harbored UNC13D and CD27 mutations, respectively; his brother carried the same CD27 heterozygous mutation. However, none of them manifested the disease. Despite the missense mutation of CD27 (c.779C>T; p.Pro260Leu) lacking previous documentation in databases, comprehensive analysis suggested non-pathogenic mutations in the CD27 variant, indicating minimal impact on T- and NK-cell functions. These results ultimately supported the option of hematopoietic stem cell transplantation (HSCT) as a successful curative therapeutic approach. As of this report, the patient has remained free of lymphoma and quiescent HLH 15.2 months post-HSCT. This study underscores the efficacy of genetic tests in identifying significant mutations and confirming their etiologies, providing an early basis for treatment decisions and the selection of suitable transplant donors.

Mitochondrial isocitrate dehydrogenase impedes CAR T cell function by restraining antioxidant metabolism and histone acetylation.

The efficacy of chimeric antigen receptor (CAR) T cell therapy is hampered by relapse in hematologic malignancies and by hyporesponsiveness in solid tumors. Long-lived memory CAR T cells are critical for improving tumor clearance and long-term protection. However, during rapid ex vivo expansion or in vivo tumor eradication, metabolic shifts and inhibitory signals lead to terminal differentiation and exhaustion of CAR T cells. Through a mitochondria-related compound screening, we find that the FDA-approved isocitrate dehydrogenase 2 (IDH2) inhibitor enasidenib enhances memory CAR T cell formation and sustains anti-leukemic cytotoxicity in vivo. Mechanistically, IDH2 impedes metabolic fitness of CAR T cells by restraining glucose utilization via the pentose phosphate pathway, which alleviates oxidative stress, particularly in nutrient-restricted conditions. In addition, IDH2 limits cytosolic acetyl-CoA levels to prevent histone acetylation that promotes memory cell formation. In combination with pharmacological IDH2 inhibition, CAR T cell therapy is demonstrated to have superior efficacy in a pre-clinical model.

HBV reactivation in patients with chronic or resolved HBV infection following BCMA-targeted CAR-T cell therapy.

B-cell maturation antigen (BCMA)-targeted chimeric antigen receptor-T cell (CAR-T) therapy is used for refractory or relapsed multiple myeloma (r/r MM). Concern of the safety and efficacy of CAR-T cell therapy in patients with chronic or resolved HBV infection is raised. In this study, we retrospectively reviewed 99 patients with r/r MM treated with BCMA-targeted CAR-T cell therapy, of which 7 (7.1%) patients had chronic HBV infection, 43 (43.4%) with resolved HBV infection, and the remaining 49 (49.49%) HBV-uninfected. Patients' characteristics before CAR-T cell administration were comparable in different status of HBV infection. Patients' liver function, cytokine levels, CAR-T cell expansion and cytokine release syndrome (CRS) grade after CAR-T cell therapy did not differ in different HBV serologic status. Furthermore, chronic HBV infection or resolved HBV infection did not affect clinical response, progress-free survival (PFS), or overall survival (OS). Four (4.04%) patients experienced HBV reactivation, 3 (6.98%) with resolved HBV infection, and 1 (14.29%) chronic HBV infection. Of 4 patients with HBV reactivation, 2 cases (50%) of severe hepatitis were noted and reported. Drops of serum IgG and elevation of alanine aminotransferase (ALT), alanine aminotransferase (AST), total bilirubin (TB) were observed in all four patients around the date of HBV reactivation.

Incidence, clinical characteristics and prognosis of tumor lysis syndrome following B-cell maturation antigen-targeted chimeric antigen receptor-T cell therapy in relapsed/refractory multiple myeloma.

Background aims: B-cell maturation antigen (BCMA)-targeted chimeric antigen receptor-T cell (CAR-T) therapy is used for refractory or relapsed multiple myeloma (r/r MM). However, CAR-T-related tumor lysis syndrome (TLS) has been observed. We aimed to elucidate the incidence, clinical and laboratory characteristics, and prognosis of CAR-T cell-related TLS. Methods: Patients (n=105) with r/r MM treated with BCMA-targeted CAR-T cell therapy were included. Patient characteristics, laboratory parameters, and clinical outcomes were assessed. Results: Eighteen (17.1%) patients developed TLS after BCMA-targeted CAR-T cell therapy. The median time till TLS onset was 8 days. Patients with TLS had steep rise in uric acid (UA), creatinine, and lactate dehydrogenase (LDH) within 6 days following CAR-T cell infusion and presented earlier and persistent escalation of cytokines (C-reactive protein [CRP], interleukin-6 [IL-6], interferon-γ [IFN-γ], and ferritin levels). All 18 patients had cytokine release syndrome (CRS), of which 13 (72.2%) developed grade 3-4 CRS. Three of 18 patients (16.7%) developed immune effector cell-associated neurotoxicity syndrome (ICANS): two patients with grade 1 ICANS and one with grade 2 ICANS. TLS development had a negative effect on the objective response rate (77.8% in the TLS group vs. 95.4% in the non-TLS group, p<0.01). During the median follow-up of 15.1 months, the median PFS was poorer of patients with TLS (median: 3.4 months in the TLS group vs. 14.7 months in the non-TLS group, p<0.001, hazard ratio [HR]=3.5 [95% confidence interval [CI] 1.5-8.5]). Also, TLS development exhibited significant effects on OS (median: 5.0 months in the TLS group vs. 39.8 months in the non-TLS group, p<0.001, hazard ratio [HR]=3.7 [95% CI 1.3-10.3]). TLS was associated with a higher tumor burden, elevated baseline creatinine and UA levels, severe CRS, pronounced CAR-T cell expansion, and corticosteroid use. Conclusion: TLS is a frequently observed CAR-T therapy complication and negatively influences clinical response and prognosis. Close monitoring for TLS should be implemented during CAR-T cell therapy, especially for those at high TLS risk.

An improved compressed sensing method for dynamic impact signals based on cubic spline interpolation.

During the dynamic acquisition of impact signals, a high sampling frequency brings significant challenges to the analog-to-digital converter and other test systems. To address this issue, in this study, an improved compressed sensing (CS) method is proposed for the measurement of impact signals based on cubic spline interpolation (CSI). According to the characteristics of the dynamic impact signal, a random non-uniform sampling strategy combining CS and CSI is presented. The CSI obviously reduces the number of observation points required by the traditional CS. To resolve the problem that the traditional orthogonal matching pursuit (OMP) algorithm can only guarantee the local optimal solution but cannot obtain the global optimal solution, an improved orthogonal matching pursuit (IOMP) algorithm is proposed. First, n atoms related to residuals are selected to build a local atomic dictionary. Subsequently, the atom most relevant to the signal observation result is selected from the local atomic dictionary. The iteration process is repeated until enough atoms are selected. The IOMP algorithm effectively improves the success rate of reconstruction. Finally, an impact signals test platform based on the Machete hammer is established. The results of theoretical simulations and several experiments indicate that the data reconstruction error of the proposed improved CS method for impact signals is approximately 5.0%.

Secondary donor-derived CD19 CAR-T therapy is safe and efficacious in acute lymphoblastic leukemia with extramedullary relapse after first autologous CAR-T therapy.

Despite the advancement of treatments, adults with relapsed/refractory (R/R) B-lineage acute lymphoblastic leukemia (B-ALL) have poor prognosis, with an expected five-year overall survival (OS) rate of 10%‒20% (Nguyen et al., 2008; Oriol et al., 2010). Extramedullary relapse of B-ALL is regarded as a high-risk factor generally associated with poor survival, occurring in about 15% to 20% of all relapsed patients (Ding et al., 2017; Sun et al., 2018). The central nervous system (CNS) and the testes are the most common sites of extramedullary relapse of B-ALL. In addition, extramedullary leukemia can appear in the skin, eyes, breasts, bones, muscles, and abdominal organs. The prognosis of relapsed extramedullary B-ALL after allogeneic hematopoietic stem cell transplantation (allo-HSCT) is extremely poor (Spyridonidis et al., 2012; Dahlberg et al., 2019). Conventional chemotherapy or radiation is often ineffective in such patients. At present, there are no optimal treatment strategies for treating extramedullary leukemia after allo-HSCT.

Treatment of allergic eosinophilic asthma through engineered IL-5-anchored chimeric antigen receptor T cells.

Severe eosinophilic asthma (SEA) is a therapy-resistant respiratory condition with poor clinical control. Treatment efficacy and patient compliance of current therapies remain unsatisfactory. Here, inspired by the remarkable success of chimeric antigen receptor-based cellular adoptive immunotherapies demonstrated for the treatment of a variety of malignant tumors, we engineered a cytokine-anchored chimeric antigen receptor T (CCAR-T) cell system using a chimeric IL-5-CD28-CD3ζ receptor to trigger T-cell-mediated killing of eosinophils that are elevated during severe asthma attacks. IL-5-anchored CCAR-T cells exhibited selective and effective killing capacity in vitro and restricted eosinophil differentiation with apparent protection against allergic airway inflammation in two mouse models of asthma. Notably, a single dose of IL-5-anchored CCAR-T cells resulted in persistent protection against asthma-related conditions over three months, significantly exceeding the typical therapeutic window of current mAb-based treatments in the clinics. This study presents a cell-based treatment strategy for SEA and could set the stage for a new era of precision therapies against a variety of intractable allergic diseases in the future.

Comparable outcomes in patients with B-cell acute lymphoblastic leukemia receiving haploidentical hematopoietic stem cell transplantation: Pretransplant minimal residual disease-negative complete remission following chimeric antigen receptor T-cell therapy versus chemotherapy.

Introduction: Chimeric antigen receptor (CAR) T-cell (CAR-T) therapy followed by haploidentical hematopoietic stem cell transplantation (haplo-HSCT) markedly improves the long-term survival of patients with refractory/relapsed (R/R) B-cell acute lymphoblastic leukemia (B-ALL). Methods: We performed a parallel comparison of transplant outcomes in 168 B-ALL patients undergoing haplo-HSCT after achieving minimal residual disease (MRD)-negative complete remission (CR) from CAR-T therapy (n = 28) or chemotherapy (n = 140) between January 2016 and August 2021. We further divided the chemotherapy group into the first CR group (chemo+CR1, n = 118) and a second or more CR group (chemo+≥CR2, n = 22). Results: With a median follow-up period of 31.0 months, the 2-year overall survival (OS), leukemia-free survival (LFS), non-relapse mortality (NRM), and relapse rates in the CAR-T and chemotherapy groups did not differ significantly (OS, 87.9% vs. 71.5 %; LFS, 72.0% vs. 66.8%; NRM, 3.9% vs. 13.7%; relapse, 24.1% vs. 19.4%). Multivariate analysis confirmed that ≥CR2 at transplantation following chemotherapy was an independent risk factor associated with poor OS (hazard ratio (HR) 4.22 [95% CI, 1.34-13.293], p = 0.014) and LFS (HR 2.57 [95% CI, 1.041-6.343], p = 0.041). The probabilities of OS and LFS at 2 years in the CAR-T group were comparable to those in the chemo+CR1 group but significantly higher than those in the chemo+≥CR2 group (OS, 87.9% vs. 37.8%, p = 0.007; LFS, 72.0% vs. 41.7%, p = 0.043). No significant differences in the incidences of NRM were noted among the three groups. Conclusions: Our results demonstrated that patients with R/R B-ALL receiving haplo-HSCT after CAR-T therapy achieved comparable outcomes to patients transplanted post-chemotherapy-based MRD-negative CR1, without increased risk of transplant-related mortality and toxicity.

Effects of music therapy on cancer-related fatigue, anxiety, and depression in patients with digestive tumors: A protocol for systematic review and meta-analysis.

BACKGROUND: Digestive tumor is one of the most common cancers, its symptoms and treatment will bring patients with anxiety, depression and other negative emotions, and cause cancer-related fatigue. As a new complementary replacement therapy, music therapy can greatly reduce cancer-related fatigue, anxiety and depression, and achieve good clinical results, but there is a lack of evidence-based medicine. The purpose of this study is to evaluate the effect of music therapy on cancer-related fatigue, anxiety, and depression in patients with digestive tumors by meta-analysis. METHOD: Computer search of Chinese and English databases: Wanfang, VP Information Chinese Journal Service Platform, China National Knowledge Infrastructure, Chinese BioMedicine Literature Database and pubmed, embase, cochrane, web of science. A comprehensive collection of relevant studies on the effects of music therapy on digestive tract cancer-related fatigue, anxiety and depression, the retrieval time is from the date of establishment to March 2021. According to the inclusion and exclusion criteria, the literature is selected, the quality of the literature is evaluated and the data are extracted. The data are analyzed by meta-analysis. RESULT: The purpose of this study is to evaluate the effect of music therapy on digestive tract cancer-related fatigue, anxiety, and depression by European Organization for Research and Treatment of Cancer Quality of Life Core Questionnaire, Hamilton Depression Scale, and Hamilton Anxiety Scale . CONCLUSION: This study will provide reliable evidence-based evidence for the clinical application of music therapy in the treatment of digestive tract cancer-related fatigue and anxiety and depression. OSF REGISTRATION NUMBER: DOI 10.17605/OSF.IO/UR4GV.

Cas9-Cleavage Sequences in Size-Reduced Plasmids Enhance Nonviral Genome Targeting of CARs in Primary Human T Cells.

T cell genome editing holds great promise to advance a range of immunotherapies but is encumbered by the dependence on difficult-to-produce and expensive viral vectors. Here, small double-stranded plasmid DNA modified to mediate high-efficiency homologous recombination is designed. The resulting chimeric antigen receptor (CAR)-T cells display a similar phenotype, transcriptional profile, and in vivo potency to CAR-T cells generated using adeno-associated viral vector. This method should simplify and accelerate the use of precision engineering to produce edited T cells for research and clinical purposes.

Engineering Cytoplasmic Signaling of CD28ζ CARs for Improved Therapeutic Functions.

Chimeric antigen receptor modified T cells (CAR-T) have yielded impressive clinical outcomes in treating hematopoietic malignancies. However, relapses have occurred in a substantial number of patients and limited the development of CAR-T therapy. Most underlying reasons for these relapses can be attributed to poor persistence and rapid exhaustion of CAR-T cells in vivo. Despite multiple strategies having been developed, how to improve CAR-T persistence or resist exhaustion while maintaining sufficient cytotoxic functions is still a great challenge. Here we discuss engineering cytoplasmic signaling as an important strategy for CAR optimization. This review summarizes recent advances showing that the anti-tumor function of CAR-T cells can be improved by optimizing the CD3ζ domain or downstream signaling of CD28ζ CAR.

[Cell therapy's poster child: Chimeric antigen receptor T cell therapy].

Chimeric antigen receptor T (CAR-T) cell therapy, which adoptively transfers engineered T cells expressing synthetic receptors to target specific antigens, has achieved great clinical success in treating hematological malignancies. Though FDA has approved two CAR-T products, CAR-T therapy can cause some side effects, such as cytokine release syndrome (CRS), neurotoxicity and B cell aplasia. Meanwhile, lacking tumor specific antigen and the suppressive tumor environment limit the efficacy of CAR-T therapy in solid tumor. This review focuses on the structural components, clinical applications and synthetic biology approaches on CAR-T cell design, and summarizes the challenges and perspectives of CAR-T therapy as a revolutionary cancer immunotherapy.

Label-Free Quantitative Proteomics Unravels Carboxypeptidases as the Novel Biomarker in Pancreatic Ductal Adenocarcinoma.

Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal cancers, with a high mortality rate and poor prognosis. However, little is known concerning the molecular mechanism of PDAC at the proteomics level. Here we report a proteomics analysis of PDAC tumor and adjacent tissues by shotgun proteomics followed by label-free quantification, and in total, 3031 and 3306 proteins were identified in three pairs of PDAC tumor and adjacent tissues, respectively; 40 of them were differentially expressed for at least three-fold in PDAC tumor tissues. Ontological and interaction network analysis highlighted the dysregulation of a set of four proteins in the carboxypeptidase family: carboxypeptidase A1 (CPA1), A2 (CPA2), B1 (CPB1), and chymotrypsin C (CTRC). Western blotting confirmed the downregulation of the carboxypeptidase network in PDAC. Immunohistochemistry of tissue microarray from 90 PDAC patients demonstrated that CPB1 was downregulated 7.07-fold (P<.0001, n=81) in tumor comparing with the peritumor tissue. Further 208 pancreatic tissues from PDAC tumor, peritumor, and pancreatis confirmed the downregulation of CPB1 in the PDAC patients. In summary, our results displayed that the expression of carboxypeptidase is significantly downregulated in PDAC tumor tissues and may be novel biomarker in the patient with PDAC.