Paclitaxel Induces Immunogenic Cell Death in Ovarian Cancer via TLR4/IKK2/SNARE-Dependent Exocytosis.

Emerging evidence shows that the efficacy of chemotherapeutic drugs is reliant on their capability to induce immunogenic cell death (ICD), thus transforming dying tumor cells into antitumor vaccines. We wanted to uncover potential therapeutic strategies that target ovarian cancer by having a better understanding of the standard-of-care chemotherapy treatment. Here, we showed in ovarian cancer that paclitaxel induced ICD-associated damage-associated molecular patterns (DAMP, such as CALR exposure, ATP secretion, and HMGB1 release) in vitro and elicited significant antitumor responses in tumor vaccination assays in vivo Paclitaxel-induced TLR4 signaling was essential to the release of DAMPs, which led to the activation of NF-κB-mediated CCL2 transcription and IkappaB kinase 2-mediated SNARE-dependent vesicle exocytosis, thus exposing CALR on the cell surface. Paclitaxel induced endoplasmic reticulum stress, which triggered protein kinase R-like ER kinase activation and eukaryotic translation initiation factor 2α phosphorylation independent of TLR4. Paclitaxel chemotherapy induced T-cell infiltration in ovarian tumors of the responsive patients; CALR expression in primary ovarian tumors also correlated with patients' survival and patient response to chemotherapy. These findings suggest that the effectiveness of paclitaxel relied upon the activation of antitumor immunity through ICD via TLR4 and highlighted the importance of CALR expression in cancer cells as an indicator of response to paclitaxel chemotherapy in ovarian cancer.

Rapid desensitization to antineoplastic drugs in an outpatient immunoallergology clinic: Outcomes and risk factors.

BACKGROUND: Hypersensitivity reactions to antineoplastic agents may lead to discontinuation of first-line treatments. Rapid drug desensitization (RDD) allows for a safe reintroduction in patients who are allergic to them. OBJECTIVE: To evaluate the safety and efficacy of the Brigham and Women's Hospital's 12-step RDD in a Portuguese patient population with cancer and to identify markers associated with breakthrough reactions (BTRs) to platins. METHODS: We conducted a retrospective review of desensitizations undertaken at the Immunoallergology Day-Care Unit of the Santa Maria Hospital in Lisbon, Portugal, from July 2008 to July 2019. Adult patients with cancer and with immediate hypersensitivity reactions were included. Skin testing was performed to platins, trastuzumab, and cetuximab. The 12-step protocol was used for most patients, and a shorter protocol was used in 9 patients who were taxane-reactive to resume regular infusions. RESULTS: A total of 1471 RDDs were performed in 272 patients to 136 platins, 124 taxanes, 13 monoclonal antibodies, and 10 other drugs. Skin test results were positive in 127 of patients who were platin-reactive (95.3%) and negative in patients who were cetuximab- and trastuzumab-reactive. There were 141 BTRs during RDD (9.6% of infusions), 79.4% induced by platins with the majority having mild reactions (68.8%). There were 8 patients who were paclitaxel-reactive, and who completed a shorter protocol and resumed regular infusions successfully. Multiple platin infusions (cutoff: ≥10) and total immunoglobulin E greater than or equal to 100 U/mL were identified as independent risk factors for BTRs in patients who were platin-reactive. CONCLUSION: This large single-center study confirmed the safety and efficacy of the 12-step RDD protocol in a diverse cancer population, providing evidence of its universal applications. Total immunoglobulin E is a potentially useful biomarker to identify high-risk patients who are platin-reactive.

Reshaping Tumor Immune Microenvironment through Acidity-Responsive Nanoparticles Featured with CRISPR/Cas9-Mediated Programmed Death-Ligand 1 Attenuation and Chemotherapeutics-Induced Immunogenic Cell Death.

Blocking immune checkpoints with monoclonal antibody has been verified to achieve potential clinical successes for cancer immunotherapy. However, its application has been impeded by the "cold" tumor microenvironment. Here, weak acidity-responsive nanoparticles co-loaded with CRISPR/Cas9 and paclitaxel (PTX) with the ability to convert "cold" tumor into "hot" tumor are reported. The nanoparticles exhibited high cargo packaging capacity, superior transfection efficiency, well biocompatibility, and effective tumor accumulation. The CRISPR/Cas9 encapsulated in nanoparticles could specifically knock out cyclin-dependent kinase 5 gene to significantly attenuate the expression of programmed death-ligand 1 on tumor cells. More importantly, PTX co-delivered in nanoparticles could significantly induce immunogenic cell death, reduce regulatory T lymphocytes, repolarize tumor-associated macrophages, and enhance antitumor immunity. Therefore, the nanoparticles could effectively convert cold tumor into hot tumor, achieve effective tumor growth inhibition, and prolong overall survival from 16 to 36 days. This research provided a referable strategy for the development of combinatorial immunotherapy and chemotherapy.

Tumor-Targeted Chemoimmunotherapy with Immune-Checkpoint Blockade for Enhanced Anti-Melanoma Efficacy.

Chemoimmunotherapy with chemotherapeutics and immunoadjuvant inhibits tumor growth by activating cytotoxic T cells. However, this process also upregulates the expression of PD-1/PD-L1 and consequently leads to immune suppression. To maximize the anti-tumor immune responses and alleviate immunosuppression, PD-L1 antibody was combined with paclitaxel (PTX) and the immunoadjuvant α-galactosylceramide (αGC), which were coencapsulated into pH-sensitive TH peptide-modified liposomes (PTX/αGC/TH-Lip) to treat melanoma and lung metastasis. Compared to treatment with PD-L1 antibody or PTX/αGC/TH-Lip alone, the combination of PD-L1 antibody and PTX/αGC/TH-Lip further elevated the tumor-specific cytotoxic T cell responses and promoted apoptosis in tumor cells, leading to enhanced anti-tumor and anti-metastatic effects. In adoptive therapy, PD-L1 antibody further alleviated immunosuppression and enhanced the anti-tumor effect of CD8+ T cells. The combination of PD-L1 antibody and chemoimmunotherapy PTX/αGC/TH-Lip provides a promising strategy for enhancing treatment for melanoma and lung metastasis.

Improvement of heavy and light chain assembly by modification of heavy chain constant region 1 (CH1): Application for the construction of an anti-paclitaxel fragment antigen-binding (Fab) antibody.

Formation of disulfide bonds between heavy and light chains is challenge for production of recombinant immunoglobulin G (IgG) and fragment antigen-binding (Fab). Insufficient formation of the bond influences productive yield and quality of recombinant IgG and Fab. To investigate how amino acid sequences of the first heavy chain constant region (CH1) effect on assembly between heavy chain (VH-CH1 or Fd) and light chain (VL-CL), the CH1 gene sequence of an anti-paclitaxel fragment antigen-binding (anti-PT Fab IgG2a) was modified using the splicing by overlap extension-polymerase chain reaction (SOE-PCR) to be gene sequences encoding amino acid sequence of IgG1, IgG2b, and IgG3 subtypes. These anti-PT Fabs were expressed in Escherichia coli and silkworm larva expression systems. The efficiency of the assembly between VH-CH1 and VL-CL was evaluated. Based on sodium dodecyl sulfate polyacrylamide gel electrophoresis and Western blot analysis, assembly between heavy of IgG1 subtype and light chain was found to be superior over other subtypes using all tested expression systems. Furthermore, reactivity analysis using an enzyme-linked immunosorbent assay (ELISA) revealed that anti-PT Fab IgG1 subtype showed the highest reactivity against target compound paclitaxel. The folding efficiency and reactivity of the anti-PT Fab was influenced by CH1 amino acid sequence, which raises the possibility that this modification can be applied to improve recombinant Fab production.

Development of a Competitive Time-Resolved Fluoroimmunoassay for Paclitaxel.

INTRODUCTION: Paclitaxel (Tax) is a diterpene alkaloid isolated from Taxus species and has proved clinically effective in treating a number of malignancies. Current quantitative analytical methods for Tax such as high-performance liquid chromatography (HPLC) often involve complicated sample preparation procedures with low recovery rates. OBJECTIVE: To establish a rapid and sensitive time-resolved fluoroimmunoassay (TRFIA) for measuring Tax in Taxus materials with convenient sample preparation and a high recovery rate. METHODS: Rabbit anti-mouse IgG was coated onto a 96-well microplate, which was then incubated with standard solutions of Tax and anti-Tax monoclonal antibody 3A3. A Eu3+ -labelled conjugate of Tax and human serum albumin was used as the tracer. The luminescent system was enhanced with a solution containing 2-naphthoyltrifluoroacetone. RESULTS: The established TRFIA showed a linear response within the Tax concentration range of 3.2 to 80 ng/mL, with a limit of detection of 1.4 ng/mL. The intra- and inter-assay coefficient of variation of the assay was 9.6% and 9.7%, respectively, with an average recovery rate from spiked samples of 108.5%. Tax contents in Taxus samples were determined using both the established TRFIA system and a previously established enzyme-linked immunosorbent (ELISA), and the results of two assays were well correlated. CONCLUSION: This TRFIA system shows a high sensitivity, precision and accuracy for detection of Tax. This assay, which is convenient and less time-consuming, allows rapid analysis of Tax and provides another option for Tax measurement for quality control of Taxus materials and products. Copyright © 2017 John Wiley & Sons, Ltd.

Different expression systems resulted in varied binding properties of anti-paclitaxel single-chain variable fragment antibody clone 1C2.

The binding properties of recombinant antibody fragments, such as affinity and specificity, determine their usefulness for therapeutic and analytical applications. Anti-paclitaxel single-chain variable fragment clone 1C2 (anti-PT scFv1C2) was expressed using Escherichia coli cell and Bombyx mori larvae expression systems. The binding characteristics of the scFvs were evaluated using indirect competitive ELISA. The linear range of binding between anti-PT scFv1C2 and paclitaxel was significantly different between the anti-PT scFv1C2s derived from E. coli (1.056-5.700 µg/ml) and B. mori (7.813-1000 ng/ml), which indicated that different expression systems resulted in different sensitivities for paclitaxel determination. In addition, the binding specificity of anti-PT scFv1C2 varied between expression systems. This finding implied that the expression system significantly affects the binding properties of recombinant antibodies, especially antibodies against low-molecular-weight targets.

Management of Hypersensitivity Reactions to Taxanes.

Taxanes are an important class of antineoplastic agents used in the treatment of a wide variety of cancers. However, paclitaxel and docetaxel, which are the most commonly used taxanes, elicit immediate hypersensitivity reactions (HSRs) in 5% to 10% of patients. Almost all patients that experience these reactions can be safely re-exposed to taxanes either through desensitization or challenge. This article describes the clinical presentation, diagnosis, and management of HSRs to taxanes and discusses the different options for their safe readministration.

Anti-HER2 immunoliposomes for co-delivery of paclitaxel and rapamycin for breast cancer therapy.

Breast cancer is the second leading cause of cancer deaths among women. Paclitaxel (PTX) is used for its treatment, however non-selectivity, rapid systemic clearance and hypersensitivity to the commercially available formulation are major drawbacks. Rapamycin (RAP), an mTOR inhibitor, acts synergistically with PTX, and thus could be used in combination with it. Drug loading into nanocarriers, particularly liposomes, has proven to enhance efficacy and reduce side-effects of chemotherapeutic drugs. Within this context, the functionalization of liposomes with antibodies for overexpressed receptors on tumor surface is a potential strategy to increase specificity and reduce side-effects. Specifically, active targeting of HER2(+) breast cancer cells can be achieved by immunoliposomes consisting of liposomes coated with an anti-HER2 monoclonal antibody, Trastuzumab. Herein, we have synthesized PTX/RAP co-loaded immunoliposomes coated with Trastuzumab, performed physicochemical characterization, and evaluated the formulations for cytotoxicity and uptake in 4T1 (triple negative) and SKBR3 (HER2 positive) cell lines. Furthermore, we aimed to compare the immunoliposomes with liposomes and solution of PTX/RAP in vivo, employing human xenograft HER2-overexpressing tumors in mouse model. The co-loaded immunoliposomes had a mean particle size of 140.3nm, a zeta potential of -9.85mV and drug encapsulation efficiency of 55.87 and 69.51, respectively for PTX and RAP. The functionalization efficiency of Trastuzumab was higher than 70% and the antibody retained HER2 binding activity. Cell studies showed increased cytotoxicity of PTX/RAP for the immunoliposome, compared to the control liposomes in SKBR3 cells, which could be attributed to enhanced uptake mediated through HER2 binding. Furthermore, immunoliposomes were better able to control tumor growth in vivo, with tumor volume averages corresponding to 25.27, 44.38 and 47.78% of tumor volumes of untreated control, PTX/RAP solution and control liposomes, respectively. Taken together, our results support the clinical development of immunoliposomes for targeted delivery of PTX and RAP to HER2-positive breast cancer.

Preclinical Antitumor Efficacy of BAY 1129980-a Novel Auristatin-Based Anti-C4.4A (LYPD3) Antibody-Drug Conjugate for the Treatment of Non-Small Cell Lung Cancer.

C4.4A (LYPD3) has been identified as a cancer- and metastasis-associated internalizing cell surface protein that is expressed in non-small cell lung cancer (NSCLC), with particularly high prevalence in the squamous cell carcinoma (SCC) subtype. With the exception of skin keratinocytes and esophageal endothelial cells, C4.4A expression is scarce in normal tissues, presenting an opportunity to selectively treat cancers with a C4.4A-directed antibody-drug conjugate (ADC). We have generated BAY 1129980 (C4.4A-ADC), an ADC consisting of a fully human C4.4A-targeting mAb conjugated to a novel, highly potent derivative of the microtubule-disrupting cytotoxic drug auristatin via a noncleavable alkyl hydrazide linker. In vitro, C4.4A-ADC demonstrated potent antiproliferative efficacy in cell lines endogenously expressing C4.4A and inhibited proliferation of C4.4A-transfected A549 lung cancer cells showing selectivity compared with a nontargeted control ADC. In vivo, C4.4A-ADC was efficacious in human NSCLC cell line (NCI-H292 and NCI-H322) and patient-derived xenograft (PDX) models (Lu7064, Lu7126, Lu7433, and Lu7466). C4.4A expression level correlated with in vivo efficacy, the most responsive being the models with C4.4A expression in over 50% of the cells. In the NCI-H292 NSCLC model, C4.4A-ADC demonstrated equal or superior efficacy compared to cisplatin, paclitaxel, and vinorelbine. Furthermore, an additive antitumor efficacy in combination with cisplatin was observed. Finally, a repeated dosing with C4.4A-ADC was well tolerated without changing the sensitivity to the treatment. Taken together, C4.4A-ADC is a promising therapeutic candidate for the treatment of NSCLC and other cancers expressing C4.4A. A phase I study (NCT02134197) with the C4.4A-ADC BAY 1129980 is currently ongoing. Mol Cancer Ther; 16(5); 893-904. ©2017 AACR.

Structures and recognition modes of toll-like receptors.

Toll-like receptors (TLRs) recognize common structural patterns in diverse microbial molecules and play central roles in the innate immune response. The structures of extracellular domains and their ligand complexes of several TLRs have been determined by X-ray crystallography. Here, we discuss recent advances on structures and activation mechanisms of TLRs. Despite the differences in interaction areas of ligand with TLRs, the extracellular domains of TLRs all adopt horseshoe-shaped structures and the overall M-shape of the TLR-ligand complexes is strikingly similar. The structural rearrangement information of TLRs sheds new light on their ligand-recognition and -activation mechanisms. Proteins 2016; 85:3-9. © 2016 Wiley Periodicals, Inc.

Risk stratification and skin testing to guide re-exposure in taxane-induced hypersensitivity reactions.

BACKGROUND: The optimal approach to patients with hypersensitivity reactions (HSRs) to taxanes has not been established. OBJECTIVE: We sought to assess the safety and efficacy of risk stratification based on the severity of the initial HSR and skin testing for guiding taxane reintroduction in patients with an HSR to these agents. METHODS: Data on 164 patients treated for a taxane-related HSR from April 2011 to August 2014 at the Dana-Farber Cancer Institute and Brigham and Women's Hospital were collected retrospectively. Patients were re-exposed to taxanes either through desensitization, challenge, or regular infusion based on the severity of the initial HSR and skin test response. Depending on the initial risk stratification and tolerance to re-exposure, patients were then treated with shorter desensitization protocols, challenge, or both with the aim of resuming regular infusions, except in patients with a severe immediate initial HSR. RESULTS: Of 138 patients desensitized, 29 (21%) had an immediate and 20 (14%) had a delayed HSR with the procedure. Of 49 patients challenged, 2 (4%) had a mild immediate and 1 (2%) had a delayed HSR with the procedure. No patients had a severe immediate HSR with desensitization or challenge. Thirty-six (22%) patients eventually resumed regular infusions. These patients were more likely to have negative skin test responses and to have experienced a delayed or mild immediate initial HSR. CONCLUSIONS: Risk stratification based on the severity of the initial HSR and skin testing to guide taxane reintroduction is safe and allows a significant number of patients to resume regular infusions.

Drug-induced immune hemolytic anemia associated with anti-carboplatin and the first example of anti-paclitaxel.

BACKGROUND: Combined chemotherapy with carboplatin and paclitaxel is first-line treatment for lung and ovarian cancer. Drug-induced antibodies to carboplatin are rare but can cause severe, even fatal, hemolysis. Paclitaxel-induced immune hemolysis has not been reported. We describe a case of immune-mediated hemolysis associated with antibodies to carboplatin and paclitaxel in a woman with ovarian cancer who had received multiple chemotherapeutic agents over 7 years, including several courses of these two drugs. She required many transfusions. During a chemotherapy infusion the patient became hypotensive, was pale, and had rigors and red urine. The nadir hematocrit was 12.4%; peak bilirubin and lactate dehydrogenase were 16.3 mg/dL and 1188 units/L, respectively. STUDY DESIGN AND METHODS: Blood samples collected within hours after chemotherapy and 2 days later were tested for antibodies to carboplatin and paclitaxel. RESULTS: The direct antiglobulin test was positive with anti-IgG (3+) and anti-C3 (2+). The plasma collected shortly after chemotherapy agglutinated carboplatin-treated red blood cells (RBCs); untreated and paclitaxel-treated RBCs both reacted at the antiglobulin test most likely due to circulating carboplatin, paclitaxel, or both drugs. Serum collected 2 days later agglutinated (titer 2) and sensitized (titer 128) carboplatin-treated RBCs; untreated and paclitaxel-treated RBCs were nonreactive. An acid eluate reacted weakly in the presence of polyethylene glycol with carboplatin-treated RBCs. The serum reacted with untreated and enzyme-treated RBCs in the presence of soluble carboplatin and paclitaxel. CONCLUSION: Anti-carboplatin and the first example of anti-paclitaxel were detected in this patient's sample.

Paclitaxel and Its Evolving Role in the Management of Ovarian Cancer.

Paclitaxel, a class of taxane with microtubule stabilising ability, has remained with platinum based therapy, the standard care for primary ovarian cancer management. A deeper understanding of the immunological basis and other potential mechanisms of action together with new dosing schedules and/or routes of administration may potentiate its clinical benefit. Newer forms of taxanes, with better safety profiles and higher intratumoural cytotoxicity, have yet to demonstrate clinical superiority over the parent compound.

Management of hypersensitivity reactions to Carboplatin and Paclitaxel in an outpatient oncology infusion center: a 5-year review.

BACKGROUND: A high incidence of hypersensitivity reactions (HSR) to carboplatin and Taxol is limiting the use of carboplatin and Taxol. OBJECTIVE: We conducted a 5-year study of all patients with HSR to carboplatin or Taxol to better understand the nature of infusion HSR and success or failure of management plans after the initial HSR. METHODS: We performed a retrospective chart review of all safety reports from the Massachusetts General Hospital outpatient chemotherapy infusion center between January 2006 and February 2011. All the patients with HSRs to carboplatin or Taxol were identified and included in the final analysis. We reviewed patient characteristics, clinical symptoms, timing, and treatment of the initial HSR, and determined if the patient was rechallenged despite an initial HSR. RESULTS: We identified 152 patients with HSR to carboplatin (n = 45) or Taxol (n = 107). Carboplatin HSR was less severe than Taxol HSR. When comparing the 2 groups, the patients with carboplatin HSRs more commonly described itchy palms and feet, generalized itch, and general urticaria and/or erythema, whereas patients with Taxol HSR more commonly described facial flushing, back pain, and chest or throat tightness (all P < .05). Among 40 patients with mild-to-moderate carboplatin HSRs, only 7 were rechallenged, and 100% tolerated rechallenge without desensitization. None of the patients with severe carboplatin HSRs (n = 5) were rechallenged. Most patients (75%) with Taxol HSRs were rechallenged, and 91% tolerated rechallenge without desensitization; the patients with a severe HSR to Taxol were less likely to be rechallenged. CONCLUSION: The clinical symptoms and timing of carboplatin HSR are distinct from Taxol HSR. Most patients with carboplatin HSR were not rechallenged, whereas most patients with Taxol HSR were successfully rechallenged.

Development of an indirect competitive enzyme-linked immunosorbent assay (icELISA) using highly specific monoclonal antibody against paclitaxel.

Paclitaxel, the major active component of the yew tree, is used as an important anti-cancer agent. To obtain the monoclonal antibody (MAb) against paclitaxel for paclitaxel determination using immunoassay, 7-xylosyltaxol was conjugated to the carrier protein bovine serum albumin (BSA) to construct the immunogen, and the ratio of hapten in XylTax-BSA conjugate was determined by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. After immunization of mice with this conjugate, hybridomas secreting MAbs against paclitaxel were obtained by fusing the splenocytes with the mouse myeloma cell line SP2/0. After hybridoma screening, the anti-paclitaxel MAb 3A3 was obtained, which showed a relatively high specificity to paclitaxel (cross-reactivities against other naturally occurred taxanes: 7-xylosyltaxol, 31.8%; cephalomannine, 6.17%; baccatin III, 10-deacetyl-baccatin III, 1-hydroxybaccatin I, 13-acetyl-9-dihydrobaccatin III and 1-acetoxyl-5-deacetyl-baccatin I, <0.11%). Using the MAb 3A3, we established an indirect competitive enzyme-linked immunosorbent assay (icELISA) for paclitaxel determination with a detection range of 0.098-312.5 µg ml(-1). Determination of paclitaxel contents in various yew tree samples with this icELISA resulted in recovery rates ranging from 92 to 94.8%, and intra- and inter-assay variations of 3.6 and 4.7%, respectively. This icELISA provides a valuable method of paclitaxel determination for various purposes.

Development of an enzyme-linked immunosorbent assay system to determine the presence of antibodies specific for taxane structures.

Taxanes, which are widely used in treatment of numerous cancer types, are well-known to induce hypersensitivity reactions (HSR), especially in the case of paclitaxel. Although the cause of the HSR is commonly thought to be a non-immunological direct effect of the diluent which is used to dissolve paclitaxel, some reports suggest the possibility of the presence of an immunological reaction to the common taxane structure. The aim of this study was to establish a method to determine the presence of anti-taxane antibodies in body fluids of patients who have previously received paclitaxel, in order to estimate the risk of the occurrence of HSR to other taxane compounds, such as docetaxel. To prepare an enzyme-linked immunosorbent assay (ELISA) plate for determining taxanes, 10-deacetylbaccatin III (DAB) was first succinylated by use of dimethylaminopyridine and succinic anhydride in dried pyridine. After the succinylation reaction, three different products were obtained, and these were confirmed as 7-succinoyl DAB (7-DAB), 10-succinoyl DAB (10-DAB), and 7,10-disuccinoyl DAB (7,10-DAB) by (1)H-NMR analysis. Each of these three products was conjugated with bovine serum albumin (BSA), and adsorbed on an ELISA plate. By using a commercially available anti-taxane monoclonal antibody as a model antibody, the detection limit of the anti-taxane antibodies on the 7-DAB-BSA-, 10-DAB-BSA-, and 7,10-DAB-BSA-conjugated ELISA plate was estimated as 0.3, 1 and 10 ng/ml, respectively. The ELISA system established in this study may therefore be useful for estimating the risk of HSR to taxanes in a patient prior to the use of these drugs.

Baccatin III, a synthetic precursor of taxol, enhances MHC-restricted antigen presentation in dendritic cells.

Baccatin III, a precursor for the semisynthesis of taxol, is widely considered to be an inactive derivative of taxol. Here we show that baccatin III efficiently enhances MHC-restricted antigen presentation in dendritic cells. Baccatin III increased both class I- and class II-restricted presentation of exogenous OVA in bone marrow-derived dendritic cells (BM-DCs). Baccatin III also increased class I-restricted presentation of virus-encoded endogenous OVA in BM-DCs. Baccatin III did not affect the phagocytic activity of BM-DCs. The antigen presentation-enhancing activity of baccatin III was examined further with nanoparticles containing OVA and baccatin III. Inclusion of baccatin III to nanoparticles containing OVA greatly enhanced their capacity to induce class I-restricted OVA peptide presentation in DCs both in vitro and in vivo. Accordingly, nanoparticles containing both OVA and baccatin III were much more efficient in inducing an OVA-specific CTL response in mice compared to those containing OVA only. These results demonstrate that baccatin III exerts immunomodulatory activities in vivo as well as in vitro on the MHC-restricted antigen presentation.

Paclitaxel acts as an adjuvant to promote both Th1 and Th2 immune responses induced by ovalbumin in mice.

Paclitaxel, a diterpenoid isolated from the bark of the Taxus cuspidate cv. Nana, was evaluated for its adjuvant effect on the immune responses in a mouse model. Fifty-six mice were randomly distributed into seven groups with 8 mice in each. Animals were subcutaneously immunized on days 1 and 21 with 100microg of paclitaxel, 10microg of ovalbumin (OVA), OVA with paclitaxel (50, 100 or 200microg) or with aluminum hydroxide (alum). Two weeks after the primary and boost immunizations, blood samples were collected for measurement of serum antibodies. Splenocytes were separated for detection of lymphocyte proliferation in responses to concanavalin A (Con A), lipopolysaccharide (LPS) and OVA, and mRNA expression of Th1 cytokines (IFN-gamma and IL-12), Th2 cytokines (IL-10 and IL-5) and transcription factors T-bet/GATA-3 (Th1/Th2 switcher). Results showed that coadministration of OVA with paclitaxel induced significantly higher IgG, IgG1, IgG2a, IgG2b, IgG3 and IgM responses than when OVA was used alone. In addition, up-regulated T-bet/GATA-3 together with significantly increased mRNA expression of IL-4, IL-10, IFN-gamma and IL-12 by splenocytes, as well as the proliferative responses of splenocytes to Con A, LPS and OVA were observed in paclitaxel-adjuvanted groups. Incubation of a murine macrophage-like cell line with paclitaxel significantly increased TNF-alpha and -10 released from the cells and expression of microRNAs such as miR-155, miR-147, miR-146a and miR-132. Therefore, paclitaxel activated both Th1 and Th2 responses. Considering its unique adjuvant effect demonstrated in this study and a safe record clinically used as an antineoplastic agent, paclitaxel could be an ideal adjuvant candidate when mixed Th1/Th2 immune responses are needed.