Combination of a novel heat shock protein 90-targeted photodynamic therapy with PD-1/PD-L1 blockade induces potent systemic antitumor efficacy and abscopal effect against breast cancers

BACKGROUND

We previously demonstrated potent antitumor activity against human breast cancer xenografts using photodynamic therapy (PDT) targeting a novel tumor-specific photosensitizer (HS201), which binds heat shock protein 90 (HS201-PDT). However, induction of systemic antitumor immunity by HS201-PDT alone or by the combination strategy with immune checkpoint blockade has yet to be determined.

METHODS

Using unilateral and bilateral implantation models of syngeneic breast tumors (E0771, MM3MG-HER2, and JC-HER3) in mice, we assessed whether HS201-PDT could induce local and systemic antitumor immunity. In an attempt to achieve a stronger abscopal effect for distant tumors, the combination strategy with anti-PD-L1 antibody was tested. Tumor-infiltrating leukocytes were analyzed by single cell RNA-sequencing and receptor-ligand interactome analysis to characterize in more detailed the mechanisms of action of the treatment and key signaling pathways involved.

RESULTS

HS201-PDT demonstrated greater tumor control and survival in immune competent mice than in immunocompromised mice, suggesting the role of induced antitumor immunity; however, survival was modest and an abscopal effect on distant implanted tumor was weak. A combination of HS201-PDT with anti-PD-L1 antibody demonstrated the greatest antigen-specific immune response, tumor growth suppression, prolonged mouse survival time and abscopal effect. The most significant increase of intratumoral, activated CD8+T cells and decrease of exhausted CD8+T cells occurred following combination treatment compared with HS201-PDT monotherapy. Receptor-ligand interactome analysis showed marked enhancement of several pathways, such as CXCL, GALECTIN, GITRL, PECAM1 and NOTCH, associated with CD8+T cell activation in the combination group. Notably, the expression of the CXCR3 gene signature was the highest in the combination group, possibly explaining the enhanced tumor infiltration by T cells.

CONCLUSIONS

The increased antitumor activity and upregulated CXCR3 gene signature induced by the combination of anti-PD-L1 antibody with HS201-PDT warrants the clinical testing of HS201-PDT combined with PD-1/PD-L1 blockade in patients with breast cancer, and the use of the CXCR3 gene signature as a biomarker.

Gene expression signatures of individual ductal carcinoma in situ lesions identify processes and biomarkers associated with progression towards invasive ductal carcinoma

Ductal carcinoma in situ (DCIS) is considered a non-invasive precursor to breast cancer, and although associated with an increased risk of developing invasive disease, many women with DCIS will never progress beyond their in situ diagnosis. The path from normal duct to invasive ductal carcinoma (IDC) is not well understood, and efforts to do so are hampered by the substantial heterogeneity that exists between patients, and even within patients. Here we show gene expression analysis from > 2,000 individually micro-dissected ductal lesions representing 145 patients. Combining all samples into one continuous trajectory we show there is a progressive loss in basal layer integrity heading towards IDC, coupled with two epithelial to mesenchymal transitions, one early and a second coinciding with the convergence of DCIS and IDC expression profiles. We identify early processes and potential biomarkers, including CAMK2N1, MNX1, ADCY5, HOXC11 and ANKRD22, whose reduced expression is associated with the progression of DCIS to invasive breast cancer.

Progression from ductal carcinoma in situ (DCIS) to invasive ductal carcinoma (IDC) remains poorly understood. Here, the authors analyse over 2700 micro-dissected samples using transcriptomics to identify genes that characterise different stages of DCIS to IDC progression, and identify IDC-associated markers within early-stage lesions.

HSP90-specific nIR probe identifies aggressive prostate cancers: translation from preclinical models to a human phase I study

A noninvasive test to discriminate indolent prostate cancers from lethal ones would focus treatment where necessary while reducing over-treatment. We exploited the known activity of heat shock protein 90 (Hsp90) as a chaperone critical for the function of numerous oncogenic drivers, including the androgen receptor and its variants, to detect aggressive prostate cancer. We linked a near infrared fluorescing molecule to an HSP90 binding drug and demonstrated that this probe (designated HS196) was highly sensitive and specific for detecting implanted prostate cancer cell lines with greater uptake by more aggressive subtypes. In a phase I human study, systemically administered HS196 could be detected in malignant nodules within prostatectomy specimens. Single-cell RNA sequencing identified uptake of HS196 by malignant prostate epithelium from the peripheral zone (AMACR+ERG+EPCAM+ cells), including SYP+ neuroendocrine cells that are associated with therapeutic resistance and metastatic progression. A theranostic version of this molecule is under clinical testing.

Blood microbiota diversity determines response of advanced colorectal cancer to chemotherapy combined with adoptive T cell immunotherapy

Human microbiota influence the response of malignancies to treatment with immune checkpoint blockade; however, their impact on other forms of immunotherapy is poorly understood. This study explored the effect of blood microbiota on clinical efficacy, represented by progression-free survival (PFS) and overall survival (OS), of combined chemotherapy and adoptive cellular therapy (ACT) in advanced colon cancer patients. Plasma was collected from colorectal cancer patients (CRC) treated with either chemotherapy alone (oxaliplatin and capecitabine) (XELOX CT alone group, n = 19), or ACT with a mixed dendritic cell/cytokine-induced killer cell product (DC-CIK) + XELOX (ICT group, n = 20). Circulating microbiota analysis was performed by PCR amplification and next-generation sequencing of variable regions V3~V4 of bacterial 16S rRNA genes. The association of the blood microbial diversity with clinical response to the therapy as measured by RECIST1.1 and OS was evaluated. The baseline Chao index of blood microbial diversity predicted prolonged PFS and OS of DC/CIK immunotherapy. More diverse blood microbiota that included Bifidobacterium, Lactobacillus, and Enterococcus were identified among responders to DC/CIK compared with non-responders. The plasma bacterial DNA copy number is inversely correlated with the CD3-/CD16+/CD56+ NK cells in circulation and decreased following DC-CIK; however, the Chao index of plasma microbiota significantly increased after administration of the DC-CIK product and this subsequent change was correlated with the number of CD3-/CD16+/CD56+ and CD8+/CD28+ cells infused. The diversity of the blood microbiome is a promising predictive marker for clinical responses to chemotherapy combined with DC-CIK. Cellular immunotherapy can affect the plasma microbiota's diversity in a manner favorable to clinical responses.

Changes in Peripheral Blood Regulatory T Cells and IL-6 and IL-10 Levels Predict Response of Pediatric Medulloblastoma and Germ Cell Tumors With Residual or Disseminated Disease to Craniospinal Irradiation

PURPOSE

Radiation therapy (RT) modulates immune cells and cytokines, resulting in both clinically beneficial and detrimental effects. The changes in peripheral blood T lymphocyte subsets and cytokines during RT for pediatric brain tumors and the association of these changes with therapeutic outcomes have not been well described.

METHODS AND MATERIALS

The study population consisted of children (n = 83, aged 3~18) with primary brain tumors (medulloblastoma, glioma, germ cell tumors (GCT), and central nervous system embryonal tumor-not otherwise specified), with or without residual or disseminated (R/D) diseases who were starting standard postoperative focal or craniospinal irradiation (CSI). Peripheral blood T lymphocyte subsets collected before and 4 weeks after RT were enumerated by flow cytometry. Plasma levels of interleukin (IL)-2, IL-4, IL-6, IL-10, tumor necrosis factor-α, interferon-γ, and IL-17A were measured by cytometric bead array.

RESULTS

Patients with R/D lesions receiving CSI (n = 32) had a post-RT increase in the frequency of CD3+T and CD8+T cells, a decrease in CD4+T cells, and an increase in regulatory T cells (Tregs) and CD8+CD28- suppressor cells, which was more predominantly seen in these patients than in other groups. In the CSI group with such R/D lesions, consisting of patients with medulloblastoma and germ cell tumors, 19 experienced a complete response (CR) and 13 experienced a partial response (PR) on imaging at 4 weeks after RT. The post/pre-RT ratio of Tregs (P = .0493), IL-6 (P = .0111), and IL-10 (P = .0070) was lower in the CR group than in the PR group. Multivariate analysis revealed that the post/pre-RT ratios of Treg, IL-6, and IL-10 were independent predictors of CR (P < .0001, P = .018, P < .0001, respectively). The areas under the receiver operating curves and confidence intervals were 0.7652 (0.5831-0.8964), 0.7794 (0.5980-0.9067), and 0.7085 (0.5223-0.8552) for IL-6, IL-10, and Treg, respectively. The sensitivities of IL-6, IL-10, and Treg to predict radiotherapeutic responses were 100%, 92.3%, and 61.5%, and specificity was 52.6%, 57.9%, and 84.2%, respectively.

CONCLUSIONS

CSI treatment to those with R/D lesions predominantly exerted an effect on antitumor immune response compared with both R/D lesion-free but exposed to focal or CSI RT and with R/D lesions and exposed to focal RT. Such CSI with R/D lesions group experiencing CR is more likely to have a decrease in immunoinhibitory molecules and cells than patients who only achieve PR. Measuring peripheral blood Treg, IL-6, and IL-10 levels could be valuable for predicting radiotherapeutic responses of pediatric brain tumors with R/D lesions to CSI for medulloblastoma and intracranial germ cell tumors.

Serial assessment of circulating T lymphocyte phenotype and receptor repertoire during treatment of non-muscle invasive bladder cancer with adoptive T cell immunotherapy

Recurrence and progression of non-muscle-invasive bladder cancer (NMIBC), frequent despite the availability of multiple treatment modalities, may be partly explained by the presence of immunosuppressive cell populations. We hypothesized that progression of disease could be prevented by the administration of an activated T cell immunotherapy (ACT) at time points when immunosuppressive populations increased in peripheral blood. In an N-of-1 study, a patient with multiple primary bladder high grade urothelial carcinomas, previously treated with standard local resection and chemotherapy but with evidence of progression, received ACT consisting of dendritic cells mixed with cytokine induced killer cells (DC/CIK), intravenously 18 times over a 6 year period at indicated time of observed increases in peripheral blood immunosuppressive CD8⁺/CD28^- cells. Peripheral blood was analyzed for T cell phenotype by flow cytometry, T cell receptor (TCR) repertoire, and circulating tumor DNA (ctDNA) by next generation sequencing (NGS) at the time of each infusion. Cystoscopy and pelvic CT scans were performed at routine intervals to assess clinical status of disease. There has been no recurrence or metastasis of urothelial carcinoma. Peripheral blood cytotoxic T cells and unique TCR clones increased and suppressive T cell populations decreased after DC/CIK infusions evidenced by the two more proof-of concept cases. ctDNA analysis detected mutations in six genes (ARID1B, MYCN, CDH23, SETD2, NOTCH4 and FAT1) which appeared at different times, but all of them disappeared after the DC-CIK infusions. These data suggest that DC/CIK infusions may be associated with beneficial changes in T cell phenotype, TCR repertoire, decreases in circulating tumor DNA and sustained recurrence-free survival.

Infiltration of metastatic lymph nodes with PD-1+ T cells is associated with improved disease-free and overall survival in resected N+ NSCLC

Tumor metastases to regional lymph nodes are associated with worse outcome for patients with resected non-small cell lung cancer (NSCLC), but there is a wide variation in survival. We hypothesized that infiltration of tumor-involved lymph nodes with activated effector T cells would impact subsequent outcome. A total of 54 lymph nodes (27 N⁺ and 15 N^- collected from 12 patients with Stage IIB (T₂N₁M₀) and 12 N^- lymph nodes collected from 10 patients with Stage IIA (T₂N₀M₀) who underwent lymphadenectomy during surgical management of their NSCLC) were analyzed for effector T cells expressing activation markers PD-1 and TIM-3 using the Opal-multiple immunofluorescence assay. The frequency of CD3⁺CD8⁺ (P=0.0001), CD3⁺CD8⁺TIM-3⁺ (P<0.0001), and CD3⁺CD8⁺TIM-3⁺Ki-67⁺ (P<0.0001) T cells was greater in lymph nodes of IIA patients compared with IIB patients; however the frequency of CD3⁺CD8⁺PD-1⁺ (P=0.0086), CD3⁺CD8⁺TIM-3⁺ (P=0.0129), CD3⁺CD8⁺PD-1⁺Ki-67⁺ (P<0.0001) and CD3⁺CD8⁺TIM-3⁺Ki-67⁺ (P=0.0001) T cells was greater among the tumor involved (N⁺) nodes of N1 patients compared with the tumor-uninvolved (N^-) nodes. The frequency of intranodal CD3⁺CD8⁺, CD3⁺CD8⁺PD-1⁺ and CD3⁺CD8⁺PD-1⁺Ki-67⁺ T cells in N⁺ nodes was associated with prolonged progression-free (PFS) and overall survival (OS). These data suggest that CD3⁺CD8⁺TIM-3⁺ T cells may suppress tumor spread to regional lymph nodes but once tumor cells metastasize to lymph nodes, CD3⁺/CD8⁺/PD-1⁺/Ki67⁺ T cells localizing to N⁺ nodes may prevent further tumor spread, resulting in prolonged survival.

Clinical efficacy of intra-cavitary infusions of autologous dendritic cell/cytokine-induced killer cell products for the treatment of refractory malignant pleural effusions and ascites

To explore the safety and efficacy of intra-cavitary infusions of autologous mixed dendritic cell (DC)-cytokine-induced killer (CIK) cell products in advanced cancer patients with malignant pleural effusions or ascites. DC-CIKs were expanded ex vivo (mean yield of 1.36×10⁹ cells (range, 0.74~4.98×10⁹)) from peripheral blood mononuclear cells obtained by repeated venipuncture or apheresis. Patients received at least 1 cycle of 3 infusions of the DC-CIKs administered by indwelling catheter into the pleural or peritoneal cavity every other day. The volume of malignant effusions was assessed radiologically. Peripheral blood lymphocyte populations were enumerated by flow cytometry. Quality of life (QoL) during the DC-CIK infusions was assessed by the EORTC QLQ-30 instrument. ctDNA sequencing was performed to analyze gene clonal load and molecular tumor burden during the infusion treatment. Thirty-seven patients with breast, lung and other malignancies were enrolled. The results showed that intra-cavitary DC-CIK infusions (16 intrapleural and 21 intraperitoneal) were well-tolerated with no grade 3/4 adverse events. There was one complete response with effusion disappearance (CR) (3%), 13 partial responses (PR) (35%), 12 with stable disease (SD) (32%) and 11 with progressive disease (PD) (30%), resulting in a clinical effusion control rate (CCR) of 70% (26/37). The total number of infused CIKs and the CD3+/CD8+ and CD8+/CD28+ T cell frequencies within the CIKs were associated with effusion control (P=0.013). Moreover, increased peripheral blood CD3+/CD8+ (P=0.035) and decreased CD4+/CD25+ T cell frequencies (P=0.041) following the DC-CIK infusions were associated with malignant effusion and ascites control. Reductions in ctDNA correlated with clinical benefit. In conclusion, intra-cavitary autologous cellular immunotherapy is an alternative method to effectively control malignant pleural effusions and ascites. The overall effusion control rate was associated with higher peripheral blood effector T cell frequencies.

Immune correlates of clinical benefit in a phase I study of hyperthermia with adoptive T cell immunotherapy in patients with solid tumors

Purpose: To characterize the T cell receptor (TCR) repertoire, serum cytokine levels, peripheral blood T lymphocyte populations, safety, and clinical efficacy of hyperthermia (HT) combined with autologous adoptive cell therapy (ACT) and either salvage chemotherapy (CT) or anti-PD-1 antibody in patients with previously treated advanced solid tumors.Materials and methods: Thirty-three (33) patients with ovarian, pancreatic, gastric, colorectal, cervical, or endometrial cancer were recruited into the following therapeutic groups: HT + ACT (n = 10), HT + ACT + anti-PD-1 inhibitor (pembrolizumab) (n = 11) and HT + ACT + CT (n = 12). Peripheral blood was collected to analyze TCR repertoire, measurements of cytokines levels and lymphocyte sub-populations before and after treatment.Results: The objective response rate (ORR) was 30% (10/33), including three complete responses (CR) (9.1%) and seven partial responses (PR) (21.2%) and a disease control rate (DCR = CR + PR + SD) of 66.7% (22 of 33). The most common adverse reactions, blistering, subcutaneous fat induration, local heat-related pain, vomiting and sinus tachycardia, were observed in association with HT. IL-2, IL-4, TNF-α, and IFN-γ levels in peripheral blood were significantly increased among the clinical responders (p < 0.05) while IL-6 and IL-10 were elevated among those with progressive disease (p < 0.05). Peripheral blood CD8⁺/CD28⁺ T cells increased (p = 0.002), while the CD4⁺/CD25⁺/CD127⁺Treg cells decreased after therapy (p = 0.012). TCR diversity was substantially increased among the clinical responders.Conclusions: Combining HT with ACT plus either CT or anti-PD-1 antibody was safe, generated clinical responses in previously treated advanced cancers, and promoted TCR repertoire diversity and favorable changes in serum IL-2, IL-4, TNF-α, and IFN-γ levels in clinical responders.

Predictive significance of T cell subset changes during ex vivo generation of adoptive cellular therapy products for the treatment of advanced non-small cell lung cancer

Adoptive T cell immunotherapy with cytokine-induced killer cells (CIKs) has been demonstrated to prolong the survival of patients with advanced non-small cell lung cancer (NSCLC). The aim of the present study was to evaluate whether the expansion of effector T cells and the decrease of regulatory T cells (Tregs) that occurred during the ex vivo generation of DC-CIKs were associated with improved clinical outcome in patients who received treatment. CIKs were generated ex vivo over a 28-day period from the peripheral blood apheresis product of 163 patients with advanced cancer (including 30 with NSCLC). CIKs were also generated from an additional cohort of 65 patients with NSCLC over a 15-day period. The progression-free survival (PFS) and overall survival (OS) time of patients treated with CIKs was determined by reviewing the patients' medical records. The number of CIKs gradually increased during the culture period and peaked at day 15, followed by a slight decline until day 28. Similarly, the percentages of T cell subtypes associated with anti-tumor activity (CD3⁺, CD3⁺CD4⁺, CD3⁺CD8⁺ and CD8⁺CD28⁺) peaked at day 15. Although the percentage of CD4⁺CD25⁺CD127⁺ Tregs increased by day 7, a decrease was subsequently observed. Among the 95 patients with NSCLC, those with a post/pre-culture ratio of CD8⁺CD28⁺ T lymphocytes >2.2 had significantly better PFS and OS compared with those with ratios ≤2.2. Those with a post/pre-culture CD4⁺CD25⁺CD127⁺ Treg ratio ≤0.6 had significantly better OS and PFS compared with those with ratios >0.6. The peak expansion of CIKs from peripheral blood mononuclear cells occurred at day 15 of ex vivo culture. PFS and OS were associated with post/pre-culture CD8⁺CD28⁺ T lymphocyte ratio >2.2 and post/pre-culture CD4⁺CD25⁺CD127⁺ Treg ratio <0.6 in the CIKs of patients with advanced NSCLC treated with adoptive T cell immunotherapy. Further efforts are underway to optimize the DC-CIK infusion for cancer immunotherapy.

Impact of synchronized anti-PD-1 with Ad-CEA vaccination on inhibition of colon cancer growth

Aim: The purpose of this study was to determine whether addition of anti-PD-1 antibody increased the immunogenicity and anti-tumor activity of Ad-CEA vaccination in a murine model of colon cancer. Methods: Ad-CEA was administered prior to implantation of MC-38-CEA cells followed by administration of anti-PD-1 antibody. CEA-specific T-cell responses were measured by flow cytometry and ELISPOT. Dynamic co-culture of splenocytes with tumor cells was conducted to analyze anti-tumor activities. Tumor infiltration by lymphocytes was measured by IHC. Tumor volume and overall survival were also recorded. Results: Ad-CEA combined with anti-PD-1 antibody showed greater anti-tumor activity compared with either alone. The combination also increased T-cell infiltration but decreased Tregs. Conclusion: Combining Ad-CEA vaccination with anti-PD-1 antibody enhanced anti-tumor activity and immune responses.

CYP1A1 genetic polymorphism is a promising predictor to improve chemotherapy effects in patients with metastatic breast cancer treated with docetaxel plus thiotepa vs. docetaxel plus capecitabine

PURPOSE

A prospective study was performed to compare the outcome for metastatic breast cancer (MBC) patients treated with docetaxel plus thiotepa (DT) or docetaxel plus capecitabine (DC), and to explore the value of CYP1A1*2C polymorphisms in predicting clinical efficacy of these chemotherapies.

METHODS

MBC patients (n = 130) were randomized to treatment with DT (n = 65) or DC (n = 65). Response rate, disease control rate, progression-free and overall survival were monitored. Genotyping of CYP1A1*2C was performed in all patients.

RESULTS

DT and DC produced similar overall disease control rates (76.9 vs 69.2%), median PFS (6.7 vs. 7.5 months) and OS (20.1 vs. 21.0 months) (P > 0.05 for all comparisons); however, DT exhibited a higher rate of control of localized liver metastases (78.6 vs 41.2%, P = 0.023). Among patients homozygous for wild-type CYP1A1*1 genotype (AA), DT treatment was associated with a significantly longer PFS (8.4 vs. 6.4 months, P = 0.019) and OS (33.4 vs. 15.8 months, P = 0.018). Conversely, among patients carrying the variant CYP1A1*2C genotype (AG/GG), DC treatment was associated with a significantly longer PFS (8.4 vs. 5.5 month, P = 0.005), and OS (28.5 vs. 19.6 months, P = 0.010). After adjusting for competing risk factors, CYP1A1*2C genotype was confirmed to be an independent predictor of PFS and OS for each chemotherapy combination.

CONCLUSIONS

Overall, DT and DC result in similar clinical efficacy for MBC patients; however, efficacy for each therapy differs depending on CYP1A1*2C genotype.

Abstract 1859: Hsp90 targeted near infrared molecular imaging to detect mammografically occult invasive lobular breast cancer

Background: Early diagnosis of Invasive lobular carcinomas (ILCs) is clinically challenging due to its histopathologic features making it difficult to detect using mammography. Because of the diffuse infiltration of ILC cells into the surrounding stroma, ILC is also associated with a higher incidence of positive resection margins after breast-conserving surgery. Therefore, there is a significant unmet need for improved imaging for early detection, clinical staging, and possibly intraoperative imaging to assess surgical margins. We propose to detect mammografically occult ILC by the in vivo detecting of malignant signaling pathways activated in ILC. Heat shock protein 90 (Hsp90) comprises 1-3% of the total cellular protein in most cells and acts as a molecular chaperone for more than 200 reported client proteins. Recently, we developed a series of tethered Hsp90 inhibitors that specifically target a tumor specific form of Hsp90 associated with poor outcomes. Using near infrared (nIR) probe-tethered Hsp90 inhibitors, we demonstrated that Hsp90 is actively re-internalized and can be used to image murine and human breast cancer in vitro and in vivo.

Methods and Results: We tested the imaging efficacy of the nIR-tethered Hsp90 inhibitor, HS196, in ILC models in vitro and in vivo. An inactive structural analog HS199 was used as a control to monitor for non-specific (non-Hsp90 dependent) uptake. Two ILC cell lines, MDA-MB-134 VI and SUM44-PE, and one patient-derived ILC xenograft, HCI-013 EI, were tested. nIR signals of HS196 in vitro and in vivo were detected by Odyssey (LI-COR) and Pearl Trilogy (LI-COR)/SPY ELITE imager (Novadaq), respectively. High uptake of HS196 was observed in vitro by both cell lines (&gt; 1 µM), while the control HS199 resulted in weaker nIR signals in these cells. In vivo imaging efficacy of HS196 was tested using HCI-013 EI xenograft in SCID-beige mice. After injection of 10 nmol compounds via tail vein, quick and stronger accumulation and longer retention of the HS196 in the ILC xenograft was observed, while HS199 showed significantly weaker accumulation and faster clearance (by 24 h after injection). Significant uptake of HS196 by HCI-013 EI tumors was confirmed by ex vivo imaging of tumors 24 h after compound injection. Histological and flow cytometry analysis of HCI-013 EI tumors showed strong nIR signals in tumor cells.

Conclusions: The non-radioactive, nIR imaging strategy, using a novel nIR-Hsp90 inhibitor compound, HS196, was effective in the non-invasive imaging of ILC tumors. This finding suggests that new molecular imaging techniques, not dependent on micro calcifications or architectural distortion, may be a novel strategy to met the need of ILC patients to detect, clinically stage and assess margins during surgical resection. Ongoing pre-clinical models will be employed and first in human testing of this approach in planned.

Citation Format: Takuya Osada, Kensuke Kaneko, Zachary Hartman, Amy Hobeika, Philip Hughes, Timothy Haystead, Michael Morse, H. Kim Lyerly. Hsp90 targeted near infrared molecular imaging to detect mammografically occult invasive lobular breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1859. doi:10.1158/1538-7445.AM2017-1859

Dendritic Cell/Cytokine-Induced Killer Cell Immunotherapy Combined with S-1 in Patients with Advanced Pancreatic Cancer: A Prospective Study

Purpose: Advanced pancreatic cancer has remained challenging to treat effectively. This study aimed to investigate the clinical effects and safety of immunotherapy with dendritic cells and cytokine-induced killer cells (DC-CIK) administered with the chemotherapy (CT) S-1 in this malignancy.Experimental Design: Consecutive patients (n = 47) with advanced pancreatic cancer were treated with either DC-CIK + S-1, DC-CIK alone, S-1 alone, or best supportive care.Results: DC-CIK plus S-1 produced significantly longer median OS and PFS (212 and 136 days) compared with DC-CIK (128 and 85 days), CT (141 and 92 days), or supportive care only (52 and 43 days; P < 0.001). After adjusting for competing risk factors, DC-CIK combined with S-1 and receipt of 2 or more cycles of DC-CIK treatment remained independent predictors of disease-free and overall survival (P < 0.05). Phenotypic analysis of PBMCs demonstrated that the CD3⁺, CD3⁺/CD4⁺, and CD8⁺/CD28⁺ T-cell subsets were elevated (P < 0.05), while the CD3⁺/CD8⁺, CD3⁺/CD16⁺/CD56⁺ and CD4⁺/CD25⁺ cell subsets were significantly decreased after DC-CIK cell therapy (P < 0.05). There were no grade 3 or 4 toxicities. In addition, the mutational frequency in cell-free tumor DNA (cfDNA) declined in 4 of 14 patients who received DC-CIK, and was associated with a more favorable survival.Conclusions: Treatment of advanced pancreatic cancer with combined DC-CIK infusions and S-1 was safe, resulted in favorable PFS and OS, and modulated the peripheral blood immune repertoire. Clin Cancer Res; 23(17); 5066-73. ©2017 AACR.

Vaccination targeting human HER3 alters the phenotype of infiltrating T cells and responses to immune checkpoint inhibition

Expression of human epidermal growth factor family member 3 (HER3), a critical heterodimerization partner with EGFR and HER2, promotes more aggressive biology in breast and other epithelial malignancies. As such, inhibiting HER3 could have broad applicability to the treatment of EGFR- and HER2-driven tumors. Although lack of a functional kinase domain limits the use of receptor tyrosine kinase inhibitors, HER3 contains antigenic targets for T cells and antibodies. Using novel human HER3 transgenic mouse models of breast cancer, we demonstrate that immunization with recombinant adenoviral vectors encoding full length human HER3 (Ad-HER3-FL) induces HER3-specific T cells and antibodies, alters the T cell infiltrate in tumors, and influences responses to immune checkpoint inhibitions. Both preventative and therapeutic Ad-HER3-FL immunization delayed tumor growth but were associated with both intratumoral PD-1 expressing CD8⁺ T cells and regulatory CD4⁺ T cell infiltrates. Immune checkpoint inhibition with either anti-PD-1 or anti-PD-L1 antibodies increased intratumoral CD8⁺ T cell infiltration and eliminated tumor following preventive vaccination with Ad-HER3-FL vaccine. The combination of dual PD-1/PD-L1 and CTLA4 blockade slowed the growth of tumor in response to Ad-HER3-FL in the therapeutic model. We conclude that HER3-targeting vaccines activate HER3-specific T cells and induce anti-HER3 specific antibodies, which alters the intratumoral T cell infiltrate and responses to immune checkpoint inhibition.

Adaptive T cell responses induced by oncolytic Herpes Simplex Virus-granulocyte macrophage-colony-stimulating factor therapy expanded by dendritic cell and cytokine-induced killer cell adoptive therapy

Purpose: Although local oncolytic viral therapy (OVT) may enhance tumor lysis, antigen release, and adaptive immune responses, systemic antitumor responses post-therapy are limited. Adoptive immunotherapy with autologous dendritic cells (DC) and cytokine-induced killer cells (DC-CIK) synergizes with systemic therapies. We hypothesized that OVT with Herpes Simplex Virus-granulocyte macrophage-colony-stimulating factor (HSV-GM-CSF) would induce adaptive T cell responses that could be expanded systemically with sequential DC-CIK therapy. Patients and Methods: We performed a pilot study of intratumoral HSV-GM-CSF OVT followed by autologous DC-CIK cell therapy. In addition to safety and clinical endpoints, we monitored adaptive T cell responses by quantifying T cell receptor (TCR) populations in pre-oncolytic therapy, post-oncolytic therapy, and after DC-CIK therapy. Results: Nine patients with advanced malignancy were treated with OVT (OrienX010), of whom seven experienced stable disease (SD). Five of the OVT treated patients underwent leukapheresis, generation, and delivery of DC-CIKs, and two had SD, whereas three progressed. T cell receptor sequencing of TCR β sequences one month after OVT therapy demonstrates a dynamic TCR repertoire in response to OVT therapy in the majority of patients with the systematic expansion of multiple T cell clone populations following DC-CIK therapy. This treatment was well tolerated and long-term event free and overall survival was observed in six of the nine patients. Conclusions: Strategies inducing the local activation of tumor-specific immune responses can be combined with adoptive cellular therapies to expand the adaptive T cell responses systemically and further studies are warranted.

The prognostic value of peripheral CD4+CD25+ T lymphocytes among early stage and triple negative breast cancer patients receiving dendritic cells-cytokine induced killer cells infusion

Objective

This study aimed to assess the prognostic value of CD4⁺CD25⁺ T lymphocyte in peripheral blood among breast cancer patients treated with adoptive T lymphocytes immunotherapy.

Methods

217 patients participated in the follow-up study. CD4⁺CD25⁺ proportion was measured by flow cytometry in peripheral T cells. The median survival was estimated by Kaplan-Meier curve, Log-rank test and Cox hazard proportion regression model, between groups of CD4⁺CD25⁺ proportion more than 5% and less than or equal to 5% in peripheral T cells.

Results

Peripheral CD4⁺CD25⁺ T lymphocytes had not a relationship with progression-free survival. It was featured that above 5% peripheral CD4⁺CD25⁺ proportion of T cells was related with the median overall survival by a shorten of 51 months (p < 0.05) with the HR 1.65 (95%CI 1.04, 2.62). Above 5% CD4⁺CD25⁺proportion of T cells produced the HR to be 1.76 (95%CI 1.07, 2.87) In stage 0-II patients, and 3.59 (95%CI 1.05, 12.29) in triple negative breast cancer patients.

Conclusion

Cellular immunity restoration recovered by adoptive T cell infusions which resulted in less proportion of peripheral CD4⁺CD25⁺T lymphocytes could be a potential prognostic indicator among early stage and triple negative patients.

Biomarkers and correlative endpoints for immunotherapy trials

Immunotherapies for lung cancer are reaching phase III clinical trial, but the ultimate success likely will depend on developing biomarkers to guide development and choosing patient populations most likely to benefit. Because the immune response to cancer involves multiple cell types and cytokines, some spatially and temporally separated, it is likely that multiple biomarkers will be required to fully characterize efficacy of the vaccine and predict eventual benefit. Peripheral blood markers of response, such as the ELISPOT assay and cytokine flow cytometry analyses of peripheral blood mononuclear cells following immunotherapy, remain the standard approach, but it is increasingly important to obtain tissue to study the immune response at the site of the tumor. Earlier clinical endpoints such as response rate and progression-free survival do not correlate with overall survival demonstrated for some immunotherapies, suggesting the need to develop other intermediary clinical endpoints. Insofar as all these biomarkers and surrogate endpoints are relevant in multiple malignancies, it may be possible to extrapolate findings to immunotherapy of lung cancer.

Biomarkers and correlative endpoints for immunotherapy trials

Immunotherapies for lung cancer are reaching phase III clinical trial, but the ultimate success likely will depend on developing biomarkers to guide development and choosing patient populations most likely to benefit. Because the immune response to cancer involves multiple cell types and cytokines, some spatially and temporally separated, it is likely that multiple biomarkers will be required to fully characterize efficacy of the vaccine and predict eventual benefit. Peripheral blood markers of response, such as the ELISPOT assay and cytokine flow cytometry analyses of peripheral blood mononuclear cells following immunotherapy, remain the standard approach, but it is increasingly important to obtain tissue to study the immune response at the site of the tumor. Earlier clinical endpoints such as response rate and progression-free survival do not correlate with overall survival demonstrated for some immunotherapies, suggesting the need to develop other intermediary clinical endpoints. Insofar as all these biomarkers and surrogate endpoints are relevant in multiple malignancies, it may be possible to extrapolate findings to immunotherapy of lung cancer.

Co-delivery of antigen and IL-12 by Venezuelan equine encephalitis virus replicon particles enhances antigen-specific immune responses and antitumor effects

We recently demonstrated that Venezuelan equine encephalitis virus-based replicon particle (VRPs) encoding tumor antigens could break tolerance in the immunomodulatory environment of advanced cancer. We hypothesized that local injection of VRP-expressing interleukin-12 (IL-12) at the site of injections of VRP-based cancer vaccines would enhance the tumor-antigen-specific T cell and antibody responses and antitumor efficacy. Mice were immunized with VRP encoding the human tumor-associated antigen, carcinoembryonic antigen (CEA) (VRP-CEA(6D)), and VRP-IL-12 was also administered at the same site or at a distant location. CEA-specific T cell and antibody responses were measured. To determine antitumor activity, mice were implanted with MC38-CEA-2 cells and immunized with VRP-CEA with and without VRP-IL-12, and tumor growth and mouse survival were measured. VRP-IL-12 greatly enhanced CEA-specific T cell and antibody responses when combined with VRP-CEA(6D) vaccination. VRP-IL-12 was superior to IL-12 protein at enhancing immune responses. Vaccination with VRP-CEA(6D) plus VRP-IL-12 was superior to VRP-CEA(6D) or VRP-IL-12 alone in inducing antitumor activity and prolonging survival in tumor-bearing mice. Importantly, local injection of VRP-IL-12 at the VRP-CEA(6D) injection site provided more potent activation of CEA-specific immune responses than that of VRP-IL-12 injected at a distant site from the VRP-CEA injections. Together, this study shows that VRP-IL-12 enhances vaccination with VRP-CEA(6D) and was more effective at activating CEA-specific T cell responses when locally expressed at the vaccine site. Clinical trials evaluating the adjuvant effect of VRP-IL-12 at enhancing the immunogenicity of cancer vaccines are warranted.

Ad5 immunity after multiple safe, homologous immunizations against tumor-associated antigens with new recombinant Ad5 vector

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Background: The major limitation for the use of Ad5 and other vectored vaccines is the inability to be effective in the presence of pre-existing or concomitant vector immunity. An Ad5-based vector with deletions of the E1 and the E2b regions (Ad5 [E1-, E2b-]), by virtue of diminished late phase viral protein expression, avoids immunological clearance and induces immune responses. Methods: The Ad5 [E1-, E2b-] platform encoding tumor associated antigen(s) (TAA) such as a modified carcinoembryonic antigen (CEA(6D)), HER2 and HPV E6/E7, were evaluated for the induction of TAA specific immune responses and anti-tumor effects in murine models. In a phase I/II clinical trial, cohorts of patients (n=25 total) with advanced colorectal cancer, refractory to prior therapies, received escalating doses of Ad5 [E1-, E2b-]-CEA(6D) (109 to 1011 vp) subcutaneously every 3 weeks for 3 immunizations. CEA-specific cell mediated immunity was measured by ELISPOT. Results: In murine immunotherapy studies, mice implanted with tumors expressing TAA and subsequently treated with the Ad5 [E1-, E2b-] platform expressing that TAA had significant inhibition of tumor progression. Pre-vaccination against the TAA utilizing the Ad5 [E1-, E2b-]-TAA resulted in inhibition of tumor establishment. In a clinical trial, patients who received the highest dose of Ad5 [E1-, E2b-]-CEA(6D) exhibited the highest levels of CEA-specific CMI responses. The induction of CEA-specific CMI responses increased over the course of the 3 injections despite the presence of pre-existing Ad5 immunity in the majority (75%) of patients. There were no drug related grade 3/4 toxicities. Conclusions: The results demonstrate that the novel Ad5 [E1-, E2b-] gene delivery platform can both break tolerance and generate significant CMI responses to the TAA CEA in the setting of both naturally acquired Ad5-specific immunity and/or immunization-induced Ad5 immunity.

Novel recombinant alphaviral and adenoviral vectors for cancer immunotherapy

Although cellular immunotherapy based on autolgous dendritic cells (DCs) targeting antigens expressed by metastatic cancer has demonstrated clinical efficacy, the logistical challenges in generating an individualized cell product create an imperative to develop alternatives to DC-based cancer vaccines. Particularly attractive alternatives include in situ delivery of antigen and activation signals to resident antigen-presenting cells (APCs), which can be achieved by novel fusion molecules targeting the mannose receptor and by recombinant viral vectors expressing the antigen of interest and capable of infecting DCs. A particular challenge in the use of viral vectors is the well-appreciated clinical obstacles to their efficacy, specifically vector-specific neutralizing immune responses. Because heterologous prime and boost strategies have been demonstrated to be particularly potent, we developed two novel recombinant vectors based on alphaviral replicon particles and a next-generation adenovirus encoding an antigen commonly overexpressed in many human cancers, carcinoembryonic antigen (CEA). The rationale for developing these vectors, their unique characteristics, the preclinical studies and early clinical experience with each, and opportunities to enhance their effectiveness will be reviewed. The potential of each of these potent recombinant vectors to efficiently generate clinically active anti-tumor immune response alone, or in combination, will be discussed.

Effect of the vaccine Ad5 [E1-, E2b-]-CEA(6D) on CEA-directed CMI responses in patients with advanced CEA-expressing malignancies in a phase I/II clinical trial

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Background: Adenovirus (Ad) vectors are promising platforms for use as cancer vaccines because of their substantial immunogenicity; however, Ad-specific neutralizing antibodies, present due to natural infection, limit their use. We created a new vector containing additional deletions of the E2b gene and observed that this Ad5 [E1-, E2b-] vector, engineered to express carcinoembryonic antigen (CEA(6D)), could induce antitumor immune responses in mice despite pre-existing Ad5 immunity. The purpose of the current translational study was to evaluate the immunologic effect of increasing doses of Ad5 [E1-, E2b-]-CEA(6D) in mice and then to extended these pre-clinical observations into a phase I/II study. Methods: Ad5 naïve female C57Bl/6 mice, 4-6 weeks old, were immunized subcutaneously 3 times at 2 week intervals with doses of 1.4X107 viral particles (vp) up to1.4X109 vp of Ad5 [E1-, E2b-]-CEA(6D). Two weeks after the last immunization, splenocytes were harvested for immune determinations. Cohorts of patients (n=25 total) with advanced colorectal cancer, refractory to prior therapies, received escalating doses of Ad5 [E1-, E2B-]-CEA(6D) (109 to 1011 vp) subcutaneously every 3 weeks for 3 immunizations.CEA-specific cell mediated immunity was measured by ELISPOT. Results: Increasing doses of Ad5 [E1-, E2b-]-CEA(6D) in mice induced increasing CEA-specifc CMI responses. Similarly, patients who received the highest dose of Ad5 [E1-, E2b-]-CEA(6D) exhibited the highest levels of CEA-specific CMI responses. The induction of CEA-specific CMI responses increased over the course of the 3 injections despite the presence of pre-existing Ad5 immunity in the majority (75%) of patients. There were no drug related grade 3/4 toxicities.Two patients with stable disease remained so during the study. All other patients experienced progressive disease; however, 1-year survival was 54%. Conclusions: Multiple homologous doses of Ad5 [E1-, E2b-]-CEA(6D) could break tolerance and generate CEA-specific CMI responses in the setting of Ad specific immunity in colorectal cancer patients.

Increasing vaccine potency through exosome antigen targeting

While many tumor associated antigens (TAAs) have been identified in human cancers, efforts to develop efficient TAA "cancer vaccines" using classical vaccine approaches have been largely ineffective. Recently, a process to specifically target proteins to exosomes has been established which takes advantage of the ability of the factor V like C1C2 domain of lactadherin to specifically address proteins to exosomes. Using this approach, we hypothesized that TAAs could be targeted to exosomes to potentially increase their immunogenicity, as exosomes have been demonstrated to traffic to antigen presenting cells (APC). To investigate this possibility, we created adenoviral vectors expressing the extracellular domain (ECD) of two non-mutated TAAs often found in tumors of cancer patients, carcinoembryonic antigen (CEA) and HER2, and coupled them to the C1C2 domain of lactadherin. We found that these C1C2 fusion proteins had enhanced expression in exosomes in vitro. We saw significant improvement in antigen specific immune responses to each of these antigens in naïve and tolerant transgenic animal models and could further demonstrate significantly enhanced therapeutic anti-tumor effects in a human HER2+ transgenic animal model. These findings demonstrate that the mode of secretion and trafficking can influence the immunogenicity of different human TAAs, and may explain the lack of immunogenicity of non-mutated TAAs found in cancer patients. They suggest that exosomal targeting could enhance future anti-tumor vaccination protocols. This targeting exosome process could also be adapted for the development of more potent vaccines in some viral and parasitic diseases where the classical vaccine approach has demonstrated limitations.

Polyclonal immune responses to antigens associated with cancer signaling pathways and new strategies to enhance cancer vaccines

Aberrant signaling pathways are a hallmark of cancer. A variety of strategies for inhibiting signaling pathways have been developed, but monoclonal antibodies against receptor tyrosine kinases have been among the most successful. A challenge for these therapies is therapeutic unresponsiveness and acquired resistance due to mutations in the receptors, upregulation of alternate growth and survival pathways, or inadequate function of the monoclonal antibodies. Vaccines are able to induce polyclonal responses that can have a multitude of affects against the target molecule. We began to explore therapeutic vaccine development to antigens associated with these signaling pathways. We provide an illustrative example in developing therapeutic cancer vaccines inducing polyclonal adaptive immune responses targeting the ErbB family member HER2. Further, we will discuss new strategies to augment the clinical efficacy of cancer vaccines by enhancing vaccine immunogenicity and reversing the immunosuppressive tumor microenvironment.

Phase I study utilizing a novel antigen-presenting cell-targeted vaccine with Toll-like receptor stimulation to induce immunity to self-antigens in cancer patients

PURPOSE

The use of tumor-derived proteins as cancer vaccines is complicated by tolerance to these self-antigens. Tolerance may be broken by immunization with activated, autologous, ex vivo generated and antigen-loaded, antigen-presenting cells (APC); however, targeting tumor antigen directly to APC in vivo would be a less complicated strategy. We wished to test whether targeted delivery of an otherwise poorly immunogenic, soluble antigen to APC through their mannose receptors (MR) would induce clinically relevant immunity.

EXPERIMENTAL DESIGN

Two phase I studies were conducted with CDX-1307, a vaccine composed of human chorionic gonadotropin beta-chain (hCG-β) fused to an MR-specific monoclonal antibody, administered either locally (intradermally) or systemically (intravenously) in patients with advanced epithelial malignancies. An initial dose escalation of single-agent CDX-1307 was followed by additional cohorts of CDX-1307 combined with granulocyte-macrophage colony-stimulating factor (GM-CSF) and the Toll-like receptor (TLR) 3 agonist polyinosinic-polycytidylic acid (poly-ICLC) and TLR7/8 agonist resiquimod to activate the APC.

RESULTS

CDX-1307 induced consistent humoral and T-cell responses to hCG-β when coadministered with TLR agonists. Greater immune responses and clinical benefit, including the longest duration of stable disease, were observed with immunization combined with local TLR agonists. Immune responses were induced equally efficiently in patients with elevated and nonelevated levels of serum hCG-β. Antibodies within the serum of vaccinated participants had tumor suppressive function in vitro. Toxicity consisted chiefly of mild injection site reactions.

CONCLUSIONS

APC targeting and activation induce adaptive immunity against poorly immunogenic self-antigens which has implications for enhancing the efficacy of cancer immunotherapy.

ADAM metallopeptidase domain 17 (ADAM17) is naturally processed through major histocompatibility complex (MHC) class I molecules and is a potential immunotherapeutic target in breast, ovarian and prostate cancers

Selection of suitable antigens is critical for the development of cancer vaccines. Most desirable are over-expressed cell surface proteins that may serve as targets for both antibodies and T cells, thus maximizing a concerted immune response. Towards this goal, we characterized the relevance of tumour necrosis factor-α-converting enzyme (ADAM17) for such targeted therapeutics. ADAM17 is one of the several metalloproteinases that play a key role in epidermal growth factor receptor (EGFR) signalling and has recently emerged as a new therapeutic target in several tumour types. In the present study, we analysed the expression profile of ADAM17 in a variety of normal and cancer cells of human origin and found that this protein is over-expressed on the surface of several types of cancer cells compared to the normal counterparts. Furthermore, we analysed the presentation of a human leucocyte antigen (HLA)-A2-restricted epitope from ADAM17 protein to specific T cells established from normal donors as well as ovarian cancer patients. Our analysis revealed that the HLA-A2-restricted epitope is processed efficiently and presented by various cancer cells and not by normal cells. Tumour-specific T cell activation results in the secretion of both interferon-γ and granzyme B that can be blocked by HLA-A2 specific antibodies. Collectively, our data present evidence that ADAM17 can be a potential target antigen to devise novel immunotherapeutic strategies against ovarian, breast and prostate cancer.

Abstract 5338: Metastatic colorectal cancer cells from patients previously treated with chemotherapy are sensitive to T cell killing mediated by CEA/CD3-bispecific T cell-engaging BiTE antibody

Carcinoembryonic antigen (CEA; CD66e, CEACAM5) is a well-characterized tumor-associated antigen that is frequently and uniformly over-expressed in human carcinomas. A novel bispecific single-chain antibody of the bispecific T cell engager (BiTE) class named MEDI-565 (also known as MT111) was generated by genetic engineering. MEDI-565 binds CEA on cancer cells and CD3 present on T cells; such binding mediates T cell killing of cancer cells expressing CEA. However, MEDI-565 effectively mediates the killing of cancer cells only if it binds concurrently to CEA on a cancer cell and to CD3 on a T cell.

We hypothesized that metastatic human colorectal cancer (CRC) previously treated with conventional chemotherapy would be sensitive to T cell-mediated killing if T cells of a sufficient magnitude could be activated against the tumor. To test this hypothesis, we selected MEDI-565 to redirect a large number of polyclonal T cells against tumors expressing CEA instead of using a cancer vaccine approach that, in general, is anticipated to elicit few antigen-specific T cells in humans.

We analyzed proliferation and lysis of CEA-positive CRC specimens that had survived prior systemic chemotherapy and biologic therapy to determine if they could be killed by patient T cells engaged by MEDI-565 in vitro. The mechanism of redirected T cell killing was also investigated.

At low concentrations (0.1 to 1 ng/mL), MEDI-565 plus T cells caused reduced proliferation and enhanced apoptosis of CEA-positive human CRC specimens. High levels of soluble CEA (≤ 1,000 ng/mL) did not affect MEDI-565-induced T cell killing of cells expressing CEA, suggesting that endogenous circulating CEA may not impair the clinical activity of MEDI-565 in patients. Cancer cell lines expressing CEA remained sensitive to T cell mediated killing despite repeated exposure to T cells and MEDI-565. These results suggest that MEDI-565/T-cell treatment may not induce escape mechanisms in cancer cells, and, thus, might be suitable for long-term and repeated treatment. Granzyme B and perforin were implicated as potential mediators of MEDI-565-induced T cell killing. Furthermore, MEDI-565 activated T cells to secrete both Tc1 (Th1) and Tc2 (Th2) type cytokines.

This study demonstrates for the first time that metastatic CRC specimens derived from patients previously treated with conventional chemotherapy can be lysed by patient T cells. Clinical testing of cancer immunotherapies such as MEDI-565 that result in exposure of tumors to large numbers of T cells is warranted.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 5338.

An adenoviral vaccine encoding full-length inactivated human Her2 exhibits potent immunogenicty and enhanced therapeutic efficacy without oncogenicity

PURPOSE

Overexpression of the breast cancer oncogene HER2 correlates with poor survival. Current HER2-directed therapies confer limited clinical benefits and most patients experience progressive disease. Because refractory tumors remain strongly HER2+, vaccine approaches targeting HER2 have therapeutic potential, but wild type (wt) HER2 cannot safely be delivered in immunogenic viral vectors because it is a potent oncogene. We designed and tested several HER2 vaccines devoid of oncogenic activity to develop a safe vaccine for clinical use.

EXPERIMENTAL DESIGN

We created recombinant adenoviral vectors expressing the extracellular domain of HER2 (Ad-HER2-ECD), ECD plus the transmembrane domain (Ad-HER2-ECD-TM), and full-length HER2 inactivated for kinase function (Ad-HER2-ki), and determined their immunogenicity and antitumor effect in wild type (WT) and HER2-tolerant mice. To assess their safety, we compared their effect on the cellular transcriptome, cell proliferation, anchorage-dependent growth, and transformation potential in vivo.

RESULTS

Ad-HER2-ki was the most immunogenic vector in WT animals, retained immunogenicity in HER2-transgenic tolerant animals, and showed strong therapeutic efficacy in treatment models. Despite being highly expressed, HER2-ki protein was not phosphorylated and did not produce an oncogenic gene signature in primary human cells. Moreover, in contrast to HER2-wt, cells overexpressing HER2-ki were less proliferative, displayed less anchorage-independent growth, and were not transformed in vivo.

CONCLUSIONS

Vaccination with mutationally inactivated, nononcogenic Ad-HER2-ki results in robust polyclonal immune responses to HER2 in tolerant models, which translates into strong and effective antitumor responses in vivo. Ad-HER2-ki is thus a safe and promising vaccine for evaluation in clinical trials.

Long term disease-free survival and T cell and antibody responses in women with high-risk Her2+ breast cancer following vaccination against Her2

Background

The HER2-inhibiting antibody trastuzumab, in combination with chemotherapy, significantly improves survival of women with resected, HER2-overexpressing breast cancers, but is associated with toxicities including a risk of cardiomyopathy. Additionally, the beneficial effect of trastuzumab is expected to decrease once the drug is discontinued. We proposed to address these concerns by using cancer vaccines to stimulate HER2 intracellular domain (ICD)-specific T cell and antibody responses.

Methods

Subjects with stage II (≥ 6 +LN), III, or stage IV breast cancerwith > 50% HER2 overexpressing tumor cells who were disease-free after surgery and adjuvant therapy were eligible. Vaccines consisted of immature, cultured DC (n = 3), mature cultured DC (n = 3), or mature Flt3-ligand mobilized peripheral blood DC (n = 1) loaded with ICD, or tetanus toxoid, keyhole limpet hemocyanin or CMV peptide as controls, and were administered intradermally/subcutaneously four times at 3 week intervals. ICD-specific T cell and antibody responses were measured. Cardiac function was determined by MUGA or ECHO; long term disease status was obtained from patient contact.

Results

All seven patients successfully underwent DC generation and five received all 4 immunizations. There were no toxicities greater than grade 1 or ejection fraction decrements below normal. Delayed-type hypersensitivity (DTH) reactions at the injection site occurred in 6/7 patients and HER2 specificity was detected by cytokine flow cytometry or ELISPOT in 5 patients. At more than 5 years of follow-up, 6/7 had detectable anti-ICD antibodies. One patient experienced a pulmonary recurrence at 4 years from their study immunizations. This recurrence was resected and they are without evidence of disease. All patients are alive and disease-free at 4.6–6.7 years of follow-up.

Conclusion

Although this was a small pilot study, the well-tolerated nature of the vaccines, the lack of cardiac toxicity, significant immunogenicity, and a 100% 4.5-year survival rate suggest that vaccination with HER2 ICD protein-containing DC is appropriate for further study in this population.

Trial Registration

ClinicalTrials.gov NCT00005956

Antigen presenting cell (APC)-targeted hCGβ vaccine for cancer therapy

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Background: CDX-1307 is a novel vaccine approach designed to target antigens directly into the endocytic compartments of dendritic cells (DCs) and other professional APCs. The β subunit of human chorionic gonadotropin (hCGβ) is selectively over-expressed by a number of epithelial tumors and has been reported to correlate with stage of disease and prognosis. We have coupled this tumor-associated antigen to a human monoclonal antibody (B11) that targets mannose receptors on human dendritic cells and macrophages, and have demonstrated the efficacy of this approach in preclinical models using hCGβ-expressing tumors and cell lines. Methods: In this phase I, dose-escalating study, sequential cohorts of 6 patients with relapsed epithelial tumors receive 4 biweekly intradermal injections of CDX-1307 at either 0.3, 1.0 or 2.5 mg, or 2.5 mg concurrent with GM-CSF. Objectives: safety and tolerability; DLT, humoral and cellular immune response, and clinical activity. Results: Enrollment in the first three cohorts (n=18) is complete with no DLTs. Common potential treatment-related toxicities were injection site reaction (n=5) and fatigue/malaise (n=4), and were generally mild to moderate in severity. One transient Grade 3 generalized allergic reaction in the 1.0 mg cohort was suspected possibly related to either a nut allergy or CDX-1307. One mixed response was seen, with variable effects on circulating hCGβ. CDX-1307 localized to dermal macrophages and DCs in post-treatment biopsies. Conclusions: Administration of CDX-1307 is well tolerated and results in antigen localization in APCs of the skin. Immune Response and tumor impact are under evaluation. Further development includes systemic delivery that may provide antigen targeting to a broad APC population, and combination with immunostimulants to generate optimal immune responses.

No significant financial relationships to disclose.

NK cell activation by dendritic cell vaccine: a mechanism of action for clinical activity

Recent reports revealed that dendritic cell (DC)-natural killer (NK) cell interaction plays an important role in tumor immunity, but few DC vaccine studies have attempted to evaluate the non-specific, yet potentially clinically relevant, NK response to immunization. In this study, we first analyzed in vitro activation of NK cells by DCs similar to those used in clinical trials. Subsequently, NK cell responses were analyzed in a phase I clinical trial of a vaccine consisting of autologous DCs loaded with a fowlpox vector encoding CEA. The data were compared with the clinical outcome of the patients. DC enhances NK activity in vitro, partly by sustaining NK cell survival and by enhancing the expression of NK-activating receptors, including NKp46 and NKG2D. Among nine patients in our clinical trial, NK cytolytic activity increased in four (range 2.5-5 times greater lytic activity) including three who had increased NK cell frequency, was stable in two and decreased in three. NKp46 and NKG2D expression showed a good correlation with the patients' NK activity. When patients were grouped by clinical activity (stable disease/no evidence of disease (stable/NE, n=5) vs progressive disease (N=4) at 3 months), the majority in the stable/NE group had increases in NK activity (P=0.016). Anti-CEA T cell response was enhanced in all the nine patients analyzed, but was not significantly different between the two groups (P=0.14). Thus, NK responses following DC vaccination may correlate more closely with clinical outcome than do T cell responses. Monitoring of NK response during vaccine studies should be routinely performed.

Recent developments in therapeutic cancer vaccines

Therapeutic cancer vaccines are being developed with the intention of treating existing tumors or preventing tumor recurrence. While the results of clinical trials, predominantly in the metastatic setting have been sobering, the central hypothesis of active immunotherapy i.e. that the human immune system can be activated to recognize and destroy tumor cells, remains a viable one. We believe that a fundamental shift in how clinical trials are performed, and what concepts they test is required to make meaningful strides towards future clinical use of cancer vaccines. First, we must reappraise whether the metastatic setting is the appropriate arena to test these agents. Second, we must arrive at a consensus on the most important biologic endpoints and rapidly test vaccines for their ability to achieve these endpoints. Third, we need to expend more effort on understanding how to manipulate the immune system beyond the initial stimulation provided by a vaccine. Fourth, in order to permit comparison of results across different studies, it would be helpful to narrow down the large number of vaccine platforms. We will discuss the current state of development of cancer vaccines and the relevance for future clinical use of these agents to treat and prevent cancers.

A phase I study of dexosome immunotherapy in patients with advanced non-small cell lung cancer

Background

There is a continued need to develop more effective cancer immunotherapy strategies. Exosomes, cell-derived lipid vesicles that express high levels of a narrow spectrum of cell proteins represent a novel platform for delivering high levels of antigen in conjunction with costimulatory molecules. We performed this study to test the safety, feasibility and efficacy of autologous dendritic cell (DC)-derived exosomes (DEX) loaded with the MAGE tumor antigens in patients with non-small cell lung cancer (NSCLC).

Methods

This Phase I study enrolled HLA A2+ patients with pre-treated Stage IIIb (N = 4) and IV (N = 9) NSCLC with tumor expression of MAGE-A3 or A4. Patients underwent leukapheresis to generate DC from which DEX were produced and loaded with MAGE-A3, -A4, -A10, and MAGE-3DPO4 peptides. Patients received 4 doses of DEX at weekly intervals.

Results

Thirteen patients were enrolled and 9 completed therapy. Three formulations of DEX were evaluated; all were well tolerated with only grade 1–2 adverse events related to the use of DEX (injection site reactions (N = 8), flu like illness (N = 1), and peripheral arm pain (N = 1)). The time from the first dose of DEX until disease progression was 30 to 429+ days. Three patients had disease progression before the first DEX dose. Survival of patients after the first DEX dose was 52–665+ days. DTH reactivity against MAGE peptides was detected in 3/9 patients. Immune responses were detected in patients as follows: MAGE-specific T cell responses in 1/3, increased NK lytic activity in 2/4.

Conclusion

Production of the DEX vaccine was feasible and DEX therapy was well tolerated in patients with advanced NSCLC. Some patients experienced long term stability of disease and activation of immune effectors

HER2 dendritic cell vaccines

HER2/neu, a tumor antigen overexpressed by a third of breast cancers, is a potential target for vaccine therapies. A particularly potent immunization strategy to induce T-cell responses against tumor antigens is to use dendritic cells (DCs) loaded with the tumor antigen. We performed two small studies to test the safety, feasibility, and immunologic and clinical responses to immunizations with in vitro-generated DCs loaded with either a human leukocyte antigen A2-restricted peptide fragment of the extracellular domain of the tumor antigen HER2 (E75) or a HER2 intracellular domain (ICD) protein in patients with high-risk resected breast cancer or metastatic cancers expressing HER2. There were no toxicities due to the immunizations in any of the patients. In the study of DCs loaded with the E75 peptide, 1 of 6 patients with metastatic HER2-expressing malignancies who completed all immunizations had stable disease for 6 months; the remainder of the patients had progressive disease. Delayed-type hypersensitivity (DTH) reactivity (2-3 mm of induration) at E75-loaded DC injection sites was observed in 2 of 5 patients evaluated but was similar at the unloaded DC injection sites. In 2 patients, the DTH sites underwent biopsy and a perivascular infiltrate of CD4 and CD8 cells was demonstrated, which was greater in the E75-loaded DC injection sites than in the unloaded DC sites. In the pilot study of ICD-loaded DC in patients with high-risk resected breast cancer, all 3 patients enrolled had no evidence of recurrence at a follow-up of up to 2.5 years. Intracellular domain-specific T-cell responses were detected directly from the peripheral blood by enzyme-linked immunospot and proliferation assay in 2 patients. We conclude that it is feasible and safe to generate and administer HER2-loaded DCs to patients with advanced HER2/neu-expressing malignancies and high-risk breast cancer. The magnitude of the immune responses generated is fairly modest, and more potent DC loading and maturation strategies will be necessary to optimize these vaccines.

Preoperative mobilization of circulating dendritic cells by Flt3 ligand administration to patients with metastatic colon cancer

PURPOSE

To evaluate preoperative dendritic cell (DC) mobilization and tumor infiltration after administration of Flt3 ligand (Flt3L) to patients with metastatic colon cancer.

PATIENTS AND METHODS

Twelve patients with colon cancer metastatic to the liver or lung received Flt3L (20 microg/kg/d subcutaneously for 14 days for one to three cycles at monthly intervals) before attempted metastasectomy. The number and phenotype of DCs mobilized into peripheral-blood mononuclear cells (PBMCs) were evaluated by flow cytometry. After surgical resection, metastatic tumor tissue was evaluated for DC infiltration. In vivo immune responses to recall antigens were measured.

RESULTS

After Flt3L administration, on average, the total number of leukocytes in the peripheral blood increased from 5.9 +/- 1.0 x 10(3)/mm(3) to 11.2 +/- 3.8 x 10(3)/mm(3) (mean +/- SD, P: =. 0001). The percentage of CD11c(+)CD14(-) DCs in PBMCs increased from 2.4% +/- 1.8% to 8.8% +/- 4.7% (P: =.004). Delayed-type hypersensitivity (DTH) responses to recall antigens (CANDIDA:, mumps, and tetanus) showed marginally significant increases in reactivity after Flt3L administration (P: =.06, P: =.03, and P: =.08, respectively). An increase in the number of DCs was observed at the periphery of the tumors of patients who received Flt3L compared with those of patients who had not.

CONCLUSION

Flt3L is capable of mobilizing DCs into the peripheral blood of patients with metastatic colon cancer and may be associated with increases in DC infiltration in the peritumoral regions. Flt3L mobilization is associated with a trend toward increased DTH responses to recall antigens in vivo. The use of Flt3L to increase circulating DCs for cancer immunotherapy should be considered.