Recent progress in antibody-based therapeutics for triple-negative breast cancer.

INTRODUCTION: Triple-negative breast cancer (TNBC) is a subtype of severely aggressive breast cancer that lacks the expression of oestrogen receptor (ER), progesterone receptor and human epidermal growth factor receptor 2 (HER2) and is highly metastatic and related to a poor prognosis. Current standard treatments are still limited to systemic chemotherapy, radiotherapy, and surgical resection. More effective treatments are urgently needed. AREAS COVERED: The immunogenicity of TNBC has provided opportunities for the development of targeted immunotherapy. In this review, we focus on the recent development in antibody-based drug modalities, including angiogenesis inhibitors, immune checkpoint inhibitors, antibody-drug conjugates, immunoconjugates, T cell-redirecting bispecific antibodies and CAR-T cells, and their mechanisms of action in TNBC. EXPERT OPINION: At present, the treatment of TNBC is still a major challenge that needs to be addressed. Novel immunotherapies are promising opportunities for improving the management of this aggressive disease.

Targeting Triple-Negative Breast Cancer with Combination Therapy of EGFR CAR T Cells and CDK7 Inhibition.

EGFR-targeted chimeric antigen receptor (CAR) T cells are potent and specific in suppressing the growth of triple-negative breast cancer (TNBC) in vitro and in vivo. However, in this study, a subset of mice soon acquired resistance, which limits the potential use of EGFR CAR T cells. We aimed to find a way to overcome the observed resistance. Transcriptomic analysis results revealed that EGFR CAR T-cell treatment induced a set of immunosuppressive genes, presumably through IFNγ signaling, in EGFR CAR T-cell-resistant TNBC tumors. The EGFR CAR T-cell-induced immunosuppressive genes were associated with EGFR CAR T-cell-activated enhancers and were especially sensitive to THZ1, a CDK7 inhibitor we screened out of a panel of small molecules targeting epigenetic modulators. Accordingly, combination therapy with THZ1 and EGFR CAR T cells suppressed immune resistance, tumor growth, and metastasis in TNBC tumor models, including human MDA-MB-231 cell-derived and TNBC patient-derived xenografts, and mouse EMT6 cell-derived allografts. Taken together, we demonstrated that transcriptional modulation using epigenetic inhibitors could overcome CAR T-cell therapy-induced immune resistance, thus providing a therapeutic avenue for treating TNBC in the clinic.

A Cohort Study on Associations between Fundus/intraocular Pressure Abnormality and Medical Check-up Items.

PURPOSE: To evaluate the associations between medical check-up items (MCI) for fundus and intraocular pressure abnormality (FIPA) diseases in the Department of Health Management Centre, the Fifth Affiliated Hospital of Sun Yat-sen University (DHMC-FHS). PATIENTS AND METHODS: Individuals who visited DHMC-FHS and underwent MCI between June 2017 to May 2019 were included, 3237 subjects. A total of 356 participants were diagnosed as FIPA and enrolled. The general clinical characteristics were collected. Diseases for FIPA diagnosed included five cohort, high intraocular pressure, diabetic retinopathy, hypertension fundus arteriosclerosis, large eye cup, and high myopia fundus changes. Possible impact factors of MCI included blood routine, B-ultrasound, heart rate, hypertension, hyperlipidemia, standard vision, cerebral arteriosclerosis, body mass, arterial/carotid arteriosclerosis, etc. Further, the Pearson's correlation coefficients and logistic regression analyses were used to examine associations between MCI and FIPA. RESULTS: The weighted study population who belonged to FIPA included 356 subjects. There were significant differences in age, IOP, habitual exercise, smoking, sleep duration (P˂0.05) between FIPA and without FIPA. And RBC, Hemoglobin, B-ultrasound abnormal event, heart rate, systolic pressure, diastolic pressure, TC, LDL-C, standard vision, cerebral arteriosclerosis, body mass index, carotid arteriosclerosis were positively correlated with high intraocular pressure, hypertension fundus arteriosclerosis and high myopia fundus changes (P < .05). Possible prognosis risk factors, higher IOP, habitual exercise and more frequent smoking affect FIPA prognosis significantly [Odds ratio (OR) = 0.53, P = .01; OR = 0.13, P = .03; OR = 0.83; P = .04, respectively]. CONCLUSION: Of FIPA participants, high intraocular pressure, hypertension fundus arteriosclerosis and high myopia fundus changes were shown a positive relationship with MCI. Control IOP, habitual exercise and less frequent smoking were regarded as positive associations with decreased FIPA. These findings could help us prevent and diagnose FIPA diseases in time via MCI.

Quantitative evaluation of protective antibody response induced by hepatitis E vaccine in humans.

Efficacy evaluation through human trials is crucial for advancing a vaccine candidate to clinics. Next-generation sequencing (NGS) can be used to quantify B cell repertoire response and trace antibody lineages during vaccination. Here, we demonstrate this application with a case study of Hecolin®, the licensed vaccine for hepatitis E virus (HEV). Four subjects are administered the vaccine following a standard three-dose schedule. Vaccine-induced antibodies exhibit a high degree of clonal diversity, recognize five conformational antigenic sites of the genotype 1 HEV p239 antigen, and cross-react with other genotypes. Unbiased repertoire sequencing is performed for seven time points over six months of vaccination, with maturation pathways characterize for a set of vaccine-induced antibodies. In addition to dynamic repertoire profiles, NGS analysis reveals differential patterns of HEV-specific antibody lineages and highlights the necessity of the long vaccine boost. Together, our study presents a quantitative strategy for vaccine evaluation in small-scale human studies.

EGFR-targeted CAR-T cells are potent and specific in suppressing triple-negative breast cancer both in vitro and in vivo.

OBJECTIVES: Triple-negative breast cancer (TNBC) is well known for its strong invasiveness, rapid recurrence and poor prognosis. Immunotherapy, including chimeric antigen receptor-modified T (CAR-T) cells, has emerged as a promising tool to treat TNBC. The identification of a specific target tumor antigen and the design of an effective CAR are among the many challenges of CAR-T therapy. METHODS: We reported that epidermal growth factor receptor (EGFR) is highly expressed in TNBC and consequently designed an optimal third generation of CAR targeting EGFR. The efficacy of primary T lymphocytes infected with EGFR CAR lentivirus (EGFR CAR-T) against TNBC was evaluated both in vitro and in vivo. The signalling pathways activated in tumor and EGFR CAR-T cells were revealed by RNA sequencing analysis. RESULTS: Third-generation EGFR CAR-T cells exerted potent and specific suppression of TNBC cell growth in vitro, whereas limited cytotoxicity was observed towards normal breast epithelial cells or oestrogen receptor-positive breast cancer cells. This capability was further demonstrated in vivo in a xenograft mouse model, with minimal off-tumor cytotoxicity. Mechanistically, in vitro stimulation with TNBC cells induced the expansion of naïve-associated EGFR CAR-T cells and enhanced their persistence. Furthermore, EGFR CAR-T cells activated the interferon γ, granzyme-perforin-PARP and Fas-FADD-caspase signalling pathways in TNBC cells. CONCLUSION: We demonstrate that EGFR is a relevant immunotherapeutic target in TNBC, and EGFR CAR-T exhibits potent and specific antitumor activity against TNBC, suggesting the potential of this third-generation EGFR CAR-T as an immunotherapy tool to treat TNBC in the clinic.

Prolonged suppression of HBV in mice by a novel antibody that targets a unique epitope on hepatitis B surface antigen.

OBJECTIVE: This study aimed to investigate the therapeutic potential of monoclonal antibody (mAb) against HBV as a novel treatment approach to chronic hepatitis B (CHB) in mouse models. METHODS: Therapeutic effects of mAbs against various epitopes on viral surface protein were evaluated in mice mimicking persistent HBV infection. The immunological mechanisms of mAb-mediated viral clearance were systematically investigated. RESULTS: Among 11 tested mAbs, a novel mAb E6F6 exhibited the most striking therapeutic effects in several HBV-persistent mice. Single-dose administration of E6F6 could profoundly suppress the levels of hepatitis B surface antigen (HBsAg) and HBV DNA for several weeks in HBV-transgenic mice. E6F6 regimen efficiently prevented initial HBV infection, and reduced viral dissemination from infected hepatocytes in human-liver-chimeric mice. E6F6-based immunotherapy facilitated the restoration of anti-HBV T-cell response in hydrodynamic injection (HDI)-based HBV carrier mice. Immunological analyses suggested that the Fcγ receptor-dependent phagocytosis plays a predominant role in E6F6-mediated viral suppression. Molecular analyses suggested that E6F6 recognises an evolutionarily conserved epitope (GPCK(R)TCT) and only forms a smaller antibody-viral particle immune complex with limited interparticle crosslinking when it binds to viral particles. This unique binding characteristic of E6F6 to HBV was possibly associated with its effective in vivo opsonophagocytosis for viral clearance. CONCLUSIONS: These results provided new insight into understanding the therapeutic role and mechanism of antibody against persistent viral infection. The E6F6-like mAbs may provide a novel immunotherapeutic agent against human chronic HBV infection.

[Values of a combination of multiple less invasive or non-invasive examinations in the diagnosis of pediatric sputum-negative pulmonary tuberculosis].

OBJECTIVE: To study the values of a combination of multiple less invasive or non-invasive examinations including chest computed tomography (CT) scan, purified protein derivative (PPD) test, erythrocyte sedimentation rate (ESR) test, and C-reactive protein (CRP) test in the diagnosis of pediatric sputum-negative pulmonary tuberculosis (TB). METHODS: A retrospective analysis was performed on the clinical data of 269 children with confirmed pulmonary TB. Clinical symptoms and test results were analyzed and compared between the sputum-negative group (161 patients) and the sputum-positive group (108 patients). RESULTS: The sputum-negative group had atypical clinical symptoms, with fewer typical or relatively specific imaging features compared with the sputum-positive group. The positive rates of PPD, ESR, and CRP tests for the sputum-negative group were 39.1%, 44.1%, and 56.5%, respectively, versus 55.6%, 79.6%, and 59.3% for the sputum-positive group. There were significant differences in the positive rates of PPD and ESR tests between the two groups (P<0.05). More than 80% of the patients in each group were diagnosed with pulmonary TB according to three or four less invasive or non-invasive tests, without significant difference in the positive rate between the two groups (P>0.05). Forty-six patients in the sputum-negative group underwent bronchoscopy, and morphological changes with a diagnostic value and/or etiological and pathological evidence were observed in 40 (87.0%) of them. CONCLUSIONS: The diagnosis rate of pediatric sputum-negative pulmonary TB can be increased by combining tests including chest CT scan, PPD test, ESR test, and CRP test. Bronchoscopy is a reliable method for the auxiliary diagnosis of pediatric sputum-negative pulmonary TB if the combining tests cannot provide compelling evidence.

[Secretory expression and biological activity analysis of an anti-H5 single-chain antibody from Pichia pastoris].

In our previous study, a panel of 52 broadly cross-reactive H5-specific monoclonal antibodies (MAbs) were generated and characterized. The 13D4, one of these MAbs, has been demonstrated to protect mice against lethal challenge by 4 strains of H5N1 avian influenza virus representing the currently prevailing genetic populations, clades 1, 2.1, 2.2, and 2.3. Here, we further cloned the gene of the 13D4 MAb and constructed a single-chain variable fragment. Then, the 13D4 single-chain antibody (scFv) was expressed in secretory maner in Pichia pastoris. The supernatant of the culture was concentrated and subjected to ammonium sulfate precipitation. The purity of the 13D4 scFv was around 90% in SDS-PAGE following ion-exchange chromatography. We further investigated its binding property using hemagglutination inhibition (HI) test and blocking ELISA. The results indicated that the 13D4 scFv shared the same binding sites and comparable HI titer with the prototype murine 13D4 Mab. In conclusion, an anti-H5 single-chain wide-spectrum neutralizing antibody is prepared successfully in yeast system.

[Identification of peptide mimotopes of an abroad-spectrum neutralizing epitope of highly pathogenic avian influenza hemagglutinin].

A monoclonal antibody (8H5), which showed strong neutralization activity against 33 strains of H5N1 viruses isolated from hosts at various regions from 2002 to 2006, was characterized in our lab recently. This result indicated the presence of highly conserved neutralizing site on hemagglutinin (HA) of various H5N1 subtypes. In the present study, the peptide phage display technique was applied to generate mimotope of the conserved neutralizing epitope recognized by 8H5 mAb. Five peptides displayed on phage were identified to specifically bind to 8H5 mAb. One of the five peptides, 123, was further displayed on the virus-like particle assembled from aa 1-149 fragment of HBcAg. The chimeric particle HBc-T123 conserved the specific binding to 8H5 mAb, and competed with H5N1 viruses for 8H5 mAb. The antiserum induced by HBc-T123 intensively stained on SF21 cells infected by recombinant baculovirus containing HA gene of YU22 virus, indicating the production of cross-reactive antibody to H5N1 HA.

[Preparation and identification of a single-chain antibody fragment against high pathogenic H5N1 avian influenza virus].

Previously, an mAb 10F7 was developed against H5N1 hemagglutinin, which was highly specific to 34 different H5N1 strains and showed good neutralizing activity. In the present study, the single-chain fragment of the antibody was cloned into a prokaryotic vector and then expressed in E. coli. The activity of the scFv was tested in hemagglution inhibition and neutralization experiment. Two H5N1 virus strains were inhibited to bind erythrocyte cells by the scFv while the H9 virus was not. Also, five H5N1 virus strains were neutralized during infecting MDCK cells. These results showed an approachable method for developing therapeutic antibody to H5N1 virus.

Isolation of human antibodies against hepatitis E virus from phage display library by immobilized metal affinity chromatography.

OBJECTIVE: To isolate human antibodies against hepatitis E virus from phage display library by a new method of panning phage antibody library based on immobilized metal affinity chromatography (IMAC). METHODS: Phage antibody library was allowed to mix with hex-His tagged expressed HEV specific antigen, NE2, in solution for adequate binding before affinity resin for hex-His was added. The non-specific phage antibodies were removed by extensive washing and the specific bound phage antibodies could then be eluted to infect TG1 or repeat the binding process for subsequent rounds of purification. The specificity of the selected human antibodies were tested by antigen competitive ELISA, human sera blocking ELISA, scFv expression, and sequence analysis. RESULTS: His-NE2 specific recombinant phages were successfully enriched after panning procedure. Two individual phage clones, 126 and 138, showed 50% inhibition in NE2 antigen competition ELISA and obvious blocking effect by HEV positive serum in blocking ELISA. Soluble scFv of 126, 138 bound to NE2 specifically. CONCLUSION: Two specific human phage antibodies against hepatitis E virus (HEV) from phage display library were isolated by immobilized metal affinity chromatography. The immobilized metal affinity chromatography applied to phage antibody selection was a helpful supplement to the selection in solution.

[Construction and preliminary application of a human natural phage antibody library with diversity].

AIM: To construct a human natural phage single-chain antibody (scFv) library with diversity. METHODS: V(H) and V(L) genes were amplified by RT-PCR and hemi-PCR from peripheral blood lymphocytes of healthy persons. The V genes were assembled to form scFv by overlap PCR and cloned into phagemid pCANTAB-5E, and then transformed into E. coli TG1 by electroporation to construct a human natural phage scFv library. The diversity and gene family of antibody gene were analysed by sequencing and the specific antibodies against various antigens were screened through bio-panning. RESULTS: A human natural phage scFv library with diversity and 2x10(8) sink size was constructed successfully. The specific human scFvs against 5 antigens were obtained by bio-panning. CONCLUSION: A human natural phage scFv library with diversity is constructed successfully and can be applied to human antibody preparation.

Variants of green fluorescent protein GFPxm.

As research progresses, fluorescent proteins useful for optical marking will evolve toward brighter, monomeric forms that are more diverse in color. We previously reported a new fluorescent protein from Aequorea macrodactyla, GFPxm, that exhibited many characteristics similar to wild-type green fluorescent protein (GFP). However, the application of GFPxm was limited because GFPxm expressed and produced fluorescence only at low temperatures. To improve the fluorescent properties of GFPxm, 12 variants were produced by site-directed mutagenesis and DNA shuffling. Seven of these mutants could produce strong fluorescence when expressed at 37 degrees C. The relative fluorescence intensities of mutants GFPxm16, GFPxm18, and GFPxm19 were higher than that of EGFP (enhanced GFP) when the expression temperature was between 25 and 37 degrees C, and mutants GFPxm16 and GFPxm163 could maintain a high fluorescence intensity even when expressed at 42 degrees C. Meanwhile, at least 4 mutants could be successfully expressed in mammalian cell lines. The fluorescence spectra of 6 of the 12 mutants had a progressive red shift. The longest excitation-emission maximum was at 514/525 nm. In addition, 3 of the 12 mutants had two excitation peaks including an UV-excitation peak, while another mutant had only one UV-excitation peak.

[Preliminary study on the conditions of solid-phase screening phage antibody library].

AIM: To explore the conditions of solid-phase screening phage antibody library and to provide the experimental basis for the design of screening project. METHODS: Diverse antibodies including HEV NE2-specific and non-specific humanized phage antibodies were used to study the screening conditions, such as the binding time of phage antibodies to antigen, the concentration of coating antigen, the washing times and elution method. RESULTS: The best binding time of positive phage antibody to antigen was 1 min. The highest positive rate of screening was obtained under the conditions of washing for 20 to 30 times and pH value of the washing solution being 5. The concentration of the coating antigen had no obvious influence on the positive rate of screening. Higher positive rate was obtained by using 10 mg/L antigen to competitively elute for 1 h. CONCLUSION: Solid-phase screening of the phage antibody library is a very complex process, in which there are close relationship between the conditions, therefore, appropriate readjustment should be made for screening conditions according to concrete conditions.

[Construction and expression of single-chain antibody of neutralizing monoclonal antibody 13D8 against hepatitis E virus].

AIM: To weaken the immunogenicity of the neutralizing monoclonal antibody (mAb) 13D8 against hepatitis E virus and express its scFv. METHODS: The V(L) and V(H) genes were cloned by RT-PCR from hybridoma cells producing mouse mAb. And then V(H)-linker-V(L) fragment (scFv) was constructed and cloned into vector pTO-T7. The scFv protein was expressed in E.coli. The activity of expressed scFv was detected by ELISA and Western blot. RESULTS: SDS-PAGE analysis showed that the scFv was highly expressed mostly in the form of inclusion body in E.coli, and the yield was up to 26.8% of the total bacteria protein. The results of indirect ELISA and Western blot showed that the expressed scFv could bind specifically to a recombinant protein in OFR2 region of HEV (NE2). The result of competitive ELISA demonstrated that the epitope recognized by the scFv was the same as that by mAb 13D8. CONCLUSION: The scFv constructed from V(H) and V(L) genes of mAb 13D8 with immunological activity was successfully expressed.

[Expression and bioactivity analysis of the fusion protein GFP-V(L) of the neutralizing monoclonal antibody MA18/7 against HBV].

AIM: To express the fusion protein of enhanced green fluorescent protein (EGFP) with the light chain variable domain of the neutralizing monoclonal antibody MA18/7 (mAb) against hepatitis B virus in E.coli, and determine its bioactivity. METHODS: The EGFP gene was cloned into vector pTO-T7 to construct an expression vector. And then according to ORF gene, MA18/7-V(L) was inserted into the 5' terminal of EGFP gene free of terminal code TAA to construct expression vector of fusion protein. The fusion protein was expressed in E.coli and its bioactivity was detected with ELISA and relative fluorescence intensity. RESULTS: The expression vector EGFP-V(L) was constructed. SDS-PAGE analysis showed that expressed fusion protein was mainly in the form of inclusion body. The fusion protein retained the property of EGFP and it could bind to V(H) to form Fv which had binding activity to pre-S1. CONCLUSION: The obtained fusion protein had good bioactivity and could be applied to further studies.

Selection of a peptide mimicking neutralization epitope of hepatitis E virus with phage peptide display technology.

AIM: To select the peptide mimicking the neutralization epitope of hepatitis E virus which bound to non-type-specific and conformational monoclonal antibodies (mAbs) 8C11 and 8H3 fromed 7-peptide phage display library, and expressed the peptide recombinant with HBcAg in E.coli, and to observe whether the recombinant HBcAg could still form virus like particle (VLP) and to test the activation of the recombinant polyprotein and chemo-synthesized peptide that was selected by mAb 8H3. METHODS: 8C11 and 8H3 were used to screen for binding peptides through a 7-peptide phage display library. After 4 rounds of panning, monoclonal phages were selected and sequenced. The obtained dominant peptide coding sequences was then synthesized and inserted into amino acid 78 to 83 of hepatitis B core antigen (HBcAg), and then expressed in E.coli. Activity of the recombinant proteins was detected by Western blotting, VLPs of the recombinant polyproteins were tested by transmission electron microscopy and binding activity of the chemo-synthesized peptide was confirmed by BIAcore biosensor. RESULTS: Twenty-one positive monoclonal phages (10 for 8C11, and 11 for 8H3) were selected and the inserted fragments were sequenced. The DNA sequence coding for the obtained dominant peptides 8C11 (N'-His-Pro-Thr-Leu-Leu-Arg-Ile-C', named 8C11A) and 8H3 (N'-Ser-Ile-Leu-Pro- Tyr-Pro-Tyr-C', named 8H3A) were then synthesized and cloned to the HBcAg vector, then expressed in E.coli. The recombinant proteins aggregated into homodimer or polymer on SDS-PAGE, and could bind to mAb 8C11 and 8H3 in Western blotting. At the same time, the recombinant polyprotein could form virus like particles (VLPs), which could be visualized on electron micrograph. The dominant peptide 8H3A selected by mAb 8H3 was further chemo-synthesized, and its binding to mAb 8H3 could be detected by BIAcore biosensor. CONCLUSION: These results implicate that conformational neutralizing epitope can be partially modeled by a short peptide, which provides a feasible route for subunit vaccine development.

Expression of ORF2 partial gene of hepatitis E virus in tomatoes and immunoactivity of expression products.

AIM: To transfer hepatitis E virus (HEV) ORF2 partial gene to tomato plants, to investigate its expression in transformants and the immunoactivity of expression products, and to explore the feasibility of developing a new type of plant-derived HEV oral vaccine. METHODS: Plant binary expression vector p1301E2, carrying a fragment of HEV open reading frame-2 (named HEV-E2), was constructed by linking the fragment to a constitutive CaMV35s promoter and nos terminator, then directly introduced into Agrobacterium tumefaciens EHA105. With leaf-disc method, tomato plants medicated by EHA105 were transformed and hygromycin-resistant plantlets were obtained in selective medium containing hygromycin. The presence and integration of foreign DNA in transgenic tomato genome were confirmed by Gus gene expression, PCR amplification and Southern dot blotting. The immunoactivity of recombinant protein extracted from transformed plants was examined by enzyme-linked immunosorbant assay (ELISA) using a monoclonal antibody specifically against HEV. ELISA was also used to estimate the recombinant protein content in leaves and fruits of the transformants. RESULTS: Seven positive lines of HEV-E2-transgenic tomato plants confirmed by PCR and Southern blotting were obtained and the immunoactivity of recombinant protein could be detected in extracts of transformants. The expression levels of recombinant protein were 61.22 ng/g fresh weight in fruits and 6.37-47.9 ng/g fresh weight in leaves of the transformants. CONCLUSION: HEV-E2 gene was correctly expressed in transgenic tomatoes and the recombinant antigen derived from them has normal immunoactivity. Transgenic tomatoes may hold a good promise for producing a new type of low-cost oral vaccine for hepatitis E virus.