A Phase I/II Trial of HER2 Vaccine-Primed Autologous T-Cell Infusions in Patients with Treatment Refractory HER2-Overexpressing Breast Cancer

PURPOSE

High levels of type I T cells are needed for tumor eradication. We evaluated whether the HER2-specific vaccine-primed T cells are readily expanded ex vivo to achieve levels needed for therapeutic infusion.

PATIENTS AND METHODS

Phase I/II nonrandomized trial of escalating doses of ex vivo-expanded HER2-specific T cells after in vivo priming with a multiple peptide-based HER2 intracellular domain (ICD) vaccine. Vaccines were given weekly for a total of three immunizations. Two weeks after the third vaccine, patients underwent leukapheresis for T-cell expansion, then received three escalating cell doses over 7- to 10-day intervals. Booster vaccines were administered after the T-cell infusions. The primary objective was safety. The secondary objectives included extent and persistence of HER2-specific T cells, development of epitope spreading, and clinical response. Patients received a CT scan prior to enrollment and 1 month after the last T-cell infusion.

RESULTS

Nineteen patients received T-cell infusions. Treatment was well tolerated. One month after the last T-cell infusion, 82% of patients had significantly augmented T cells to at least one of the immunizing epitopes and 81% of patients demonstrated enhanced intramolecular epitope spreading compared with baseline (P < 0.05). There were no complete responses, one partial response (6%), and eight patients with stable disease (47%), for a disease control rate of 53%. The median survival for those with progressive disease was 20.5 months and for responders (PR+SD) was 45.0 months.

CONCLUSIONS

Adoptive transfer of HER2 vaccine-primed T cells was feasible, was associated with minimal toxicity, and resulted in an increased overall survival in responding patients. See related commentary by Crosby et al., p. 3256.

Society for Immunotherapy of Cancer (SITC) clinical practice guideline on immunotherapy for the treatment of gynecologic cancer

Advanced gynecologic cancers have historically lacked effective treatment options. Recently, immune checkpoint inhibitors (ICIs) have been approved by the US Food and Drug Administration for the treatment of cervical cancer and endometrial cancer, offering durable responses for some patients. In addition, many immunotherapy strategies are under investigation for the treatment of earlier stages of disease or in other gynecologic cancers, such as ovarian cancer and rare gynecologic tumors. While the integration of ICIs into the standard of care has improved outcomes for patients, their use requires a nuanced understanding of biomarker testing, treatment selection, patient selection, response evaluation and surveillance, and patient quality of life considerations, among other topics. To address this need for guidance, the Society for Immunotherapy of Cancer (SITC) convened a multidisciplinary panel of experts to develop a clinical practice guideline. The Expert Panel drew on the published literature as well as their own clinical experience to develop evidence- and consensus-based recommendations to provide guidance to cancer care professionals treating patients with gynecologic cancer.

Abstract 5112: Immune biomarkers of clinical response after NSAID treatment in combination with vaccination targeting EGFR-COX2-CDC25B in the APC(Min/+) mouse model

Studies from our group have shown that administration of NSAIDs in mouse models of Familial Adenomatous Polyposis (FAP) results in a decrease in the development in small intestinal polyps with a significant increase in CD8 tumor infiltrating lymphocytes (TIL) and downregulation of PD-L1 on tumors. Furthermore, we have demonstrated that NSAIDs could be used in combination with vaccination to even further reduce the development of intestinal polyps. We questioned what tissue specific biomarkers could define the efficacy of response with the combination treatment. APC(Min/+) male and female mice (4-6 weeks old) were immunized with a multi-antigen (EGFR, COX2, CDC25B) peptide vaccine with CFA/IFA as an adjuvant. Control mice received immune adjuvant alone. Regular chow or chow containing 400 ppm naproxen was provided intermittently (3 weeks on, 3 weeks off for 3 cycles) or continuously (18 weeks on) at the initiation of the vaccine regimen. Animals were euthanized at 22 weeks and tumors quantified. TIL were evaluated by flow cytometry. Since intermittent naproxen treatment was just as effective at inhibiting tumor development as continuous naproxen treatment, with or without vaccine, we did not differentiate between NSAID regimens. We observed an increase in CD8+ (83%; p&lt;0.0001), Tbet+CD4+ (94%; p&lt;0.001), effector memory (EM) CD4+ (76%; p&lt;0.0001) and EM CD8+ (94%; p&lt;0.0001) TIL in the tumors that did develop in the mice treated with the combination NSAID and vaccination as compared to control. There was increased CD8+ (Pearson correlation coefficient: −0.506, p&lt;0001), Tbet+CD4+ (Pearson correlation coefficient: -0.6222, p&lt;0.001), EM CD4+ (Pearson correlation coefficient: 0.-6074, p&lt;0.001) and EM CD8+ (Pearson correlation coefficient: -0.7155, p&lt;0.001) in mice with greater tumor inhibition than those with less protection. Receiver operator curves revealed that CD8+ (AUC: 0.7623; p=0.002), Tbet+CD4+ (AUC 0.7273; p=0.008), EM CD4+ (AUC 0.6782; p=0.04) and EM CD8 (AUC 0.7897; p&lt;0.001) TIL can differentiate mice receiving the combination of NSAID and vaccination as compared to either monotherapy alone. These data define potential biomarkers of response that can guide human clinical trials of NSAIDs +/- vaccination in patients with FAP.

Citation Format: Denise L. Cecil, Ying Liu, Lauren Corulli, Mary L. Disis. Immune biomarkers of clinical response after NSAID treatment in combination with vaccination targeting EGFR-COX2-CDC25B in the APC(Min/+) mouse model. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5112.

Unexpected Liver and Kidney Pathology in C57BL/6J Mice Fed a High-fat Diet and Given Azoxymethane to Induce Colon Cancer

Multiple animal models have been developed to investigate the pathogenesis of colorectal cancer and to evaluate potential treatments. One model system uses azoxymethane, a metabolite of cycasin, alone and in conjunction with dextran sodium sulfate to induce colon cancer in rodents. Azoxymethane is metabolized by hepatic P450 enzymes and can also be eliminated through the kidneys. In this study, C57BL/6J mice were fed either standard or high-fat diet and then all mice received azoxymethane at 10 mg/kg body weight twice a week for 6 wk. Shortly after the end of treatment, high mortality occurred in mice in the high-fat diet group. Postmortem examination revealed hepatic and renal pathology in mice on both diets. Histologic changes in liver included hepatocytomegaly with nuclear pleomorphism and bile duct hyperplasia accompanied by mixed inflammatory-cell infiltrates. Changes in the kidneys ranged from basophilia of tubular epithelium to tubular atrophy. The results indicate that further optimization of this model is needed when feeding a high-fat diet and giving multiple azoxymethane doses to induce colon cancer in C57BL/6J mice.

Novel peptide-based vaccine targeting heat shock protein 90 induces effective antitumor immunity in a HER2+ breast cancer murine model

Background

Heat shock protein 90 (HSP90) is a protein chaperone for most of the important signal transduction pathways in human epidermal growth factor receptor 2-positive (HER2+) breast cancer, including human epidermal growth factor receptor 2, estrogen receptor, progesterone receptor and Akt. The aim of our study is to identify peptide-based vaccines and to develop an effective immunotherapeutics for the treatment of HER2+ breast cancer.

Methods

HSP90-derived major histocompatibility complex (MHC) class II epitopes were selected using in silico algorithms and validated by enzyme-linked immunospot (ELISPOT). In vivo antitumor efficacy was evaluated in MMTVneu-transgenic mice. HSP90 peptide-specific systemic T-cell responses were assessed using interferon gamma ELISPOT assay, and immune microenvironment in tumors was evaluated using multiplex immunohistochemistry and TCRβ sequencing.

Results

First, candidate HSP90-derived MHC class II epitopes with high binding affinities across multiple human HLA class II genotypes were identified using in silico algorithms. Among the top 10 peptides, p485 and p527 were selected as promising Th1 immunity-inducing epitopes with low potential for Th2 immunity induction. The selected MHC class II HSP90 peptides induced strong antigen-specific T cell responses, which was induced by cross-priming of CD8⁺ T cells in vivo. The HSP90 peptide vaccines were effective in the established tumor model, and their efficacy was further enhanced when combined with stimulator of interferon genes (STING) agonist and/or anticytotoxic T lymphocyte-associated antigen-4 antibody in MMTVneu-transgenic mice. Increased tumor rejection was associated with increased systemic HSP90-specific T-cell responses, increased T-cell recruitment in tumor microenvironment, intermolecular epitope spreading, and increased rearrangement of TCRβ by STING agonist.

Conclusions

In conclusion, we have provided the first preclinical evidence of the action mechanism of HSP90 peptide vaccines with a distinct potential for improving breast cancer treatment.

Anti-tumor activity of a T-helper 1 multiantigen vaccine in a murine model of prostate cancer

Prostate cancer is one of the few malignancies that includes vaccination as a treatment modality. Elements of an effective cancer vaccine should include the ability to elicit a Type I T-cell response and target multiple antigenic proteins expressed early in the disease. Using existing gene datasets encompassing normal prostate tissue and tumors with Gleason Score ≤ 6 and ≥ 8, 10 genes were identified that were upregulated and conserved in prostate cancer regardless of the aggressiveness of disease. These genes encoded proteins also expressed in prostatic intraepithelial neoplasia. Putative Class II epitopes derived from these proteins were predicted by a combination of algorithms and, using human peripheral blood, epitopes which selectively elicited IFN-γ or IL-10 dominant antigen specific cytokine secretion were determined. Th1 selective epitopes were identified for eight antigens. Epitopes from three antigens elicited Th1 dominant immunity in mice; PSMA, HPN, and AMACR. Each single antigen vaccine demonstrated significant anti-tumor activity inhibiting growth of implanted Myc-Cap cells after immunization as compared to control. Immunization with the combination of antigens, however, was superior to each alone in controlling tumor growth. When vaccination occurred simultaneously to tumor implant, multiantigen immunized mice had significantly smaller tumors than controls (p = 0.002) and a significantly improved overall survival (p = 0.0006). This multiantigen vaccine shows anti-tumor activity in a murine model of prostate cancer.

Abstract 3380: Seven autoantibody panel, validated in two independent patient serum collections, can detect women with DCIS and invasive breast cancer

Mammography is essential to identify early breast cancer but the sensitivity is dependent on breast characteristics. A serum-based biomarker used along with mammography to identify lesions that need to be biopsied may improve the sensitivity of mammography and reduce the number of biopsies needed. We have identified a panel of autoantibodies found in early breast cancer. An autoantibody biomarker is ideal because antibody immunity can be detected with very low levels of antigen with direct antigen recognition by B cells resulting in clonal amplification of antigen specific plasma cells. Work in our laboratory has identified tumor-associated proteins present in pre-malignant tumors that are necessary for survival of human breast cancer cells across breast cancer subtypes. Increased autoantibodies to seven of these early tumor-associated proteins (PDIA6, KRT8, SERBP1, ARPC2, RRM2, AURKA, and NDC80) were present in the sera of women with DCIS and invasive breast cancer in two independent serum collections but not in control women with no known breast lesions.

The presence of autoantibodies in the discovery set was evaluated in 185 individuals: 42 control women, 12 women with hyperplasia, 36 patients with fibroadenoma, 59 patients with ductal carcinoma in situ (DCIS), and 36 patients with invasive breast cancer (IBC). The validation set was evaluated in 228 individuals: 50 control patients, 50 patients with fibroadenoma, 18 patients with hyperplasia, 50 patients with DCIS, and 60 patients with IBC, 20 with hormone receptor positive (HR+) HER2 negative, 20 with HER2+, and 20 triple negative (TN). We defined a positive autoantibody response as over 2 standard deviations above the mean found in control women. All seven autoantibodies could predict patients with hyperplasia, fibroadenoma, DCIS, and IBC in both the discovery and validation sets. For example, the seven-antibody panel could identify DCIS from control women with AUC of 0.95 (95% CI 0.912 to 0.995, p&lt;0.0001) and validation set AUC 0.63 (95% CI 0.52 to 0.74, p=0.026). The seven-antibody panel could identify IBC from control women with AUC of 0.85 (95% CI 0.73 to 0.97, p&lt;0.0001) and validation 0.70 (95% CI 0.60 to 0.79, p&lt;0.0001). Furthermore, the seven-antibody panel could identify women with each of the breast cancer subtypes as compared to control women. Women with HR+HER2- breast cancer could be detected with AUC 0.69 (95% CI 0.55 to 0.83 p=0.014), women with HER2+ breast cancer could be detected with AUC 0.69 (95% CI 0.52 to 0.90, p=0.02), and women with triple negative breast cancer could be detected with AUC 0.69 (95% CI 0.55 to 0.83, p=0.002) in the validation set. Future studies will evaluate this panel in a prospective study at the time of mammography to identify a serum biomarker that will improve sensitivity of mammography.

Citation Format: Sasha Elizabeth Stanton, Jason Schlumbohm, Erik Ramos, Charles Drescher, Jeffrey Marks, Mary L. Disis. Seven autoantibody panel, validated in two independent patient serum collections, can detect women with DCIS and invasive breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3380.

Optimizing a multi cancer antigen plasmid-based vaccine using an in situ prediction model

Little is known about optimization of a class II restricted plasmid-based vaccine targeting multiple cancer antigens. We set out to define parameters of an in situ prediction model in vaccine design for optimal immunogenicity. Using previously defined immunogenic class II epitopes from five cancer antigens, we evaluated the effects of using linkers between antigens and varying the antigen order. The construct with linkers was superior to the construct without linkers. The mice receiving the vaccine with linkers developed a greater magnitude (p&lt;0.0001), incidence and breadth IFN-g immune response. To determine the optimal antigen order, the sequences of all possible permutations were generated. Each sequence was evaluated in four publicly available algorithms to assess potential generation of immunity and physiochemical properties of the fusion protein. Of all parameters assessed, only predicted class II immunogenicity, in vivo half-life and percent of epitopes in helical secondary structure differed considerably among the constructs. We evaluated three constructs with similarly high class II immunogenicity; one with (A) long in vivo half-life and high percent in helices, one with (B) short half-life and high percent in helices or one with (C) short half-life and low percent in helices. Construct A generated a higher magnitude IFN-g response than Construct B or C (p&lt;0.006 for all). While there was 100% incidence of an immune response to all constructs, the breadth of the response for Construct A was greater than the other two constructs. Class II immunogenicity, in vivo half-life and the percent of the protein in a helical secondary structure can be used to discern the most immunogenic multi-antigen plasmid vaccine construct.

Metabolic adaptation of ovarian tumors in patients treated with an IDO1 inhibitor constrains antitumor immune responses

To uncover underlying mechanisms associated with failure of indoleamine 2,3-dioxygenase 1 (IDO1) blockade in clinical trials, we conducted a pilot, window-of-opportunity clinical study in 17 patients with newly diagnosed advanced high-grade serous ovarian cancer before their standard tumor debulking surgery. Patients were treated with the IDO1 inhibitor epacadostat, and immunologic, transcriptomic, and metabolomic characterization of the tumor microenvironment was undertaken in baseline and posttreatment tumor biopsies. IDO1 inhibition resulted in efficient blockade of the kynurenine pathway of tryptophan degradation and was accompanied by a metabolic adaptation that shunted tryptophan catabolism toward the serotonin pathway. This resulted in elevated nicotinamide adenine dinucleotide (NAD⁺), which reduced T cell proliferation and function. Because NAD⁺ metabolites could be ligands for purinergic receptors, we investigated the impact of blocking purinergic receptors in the presence or absence of NAD⁺ on T cell proliferation and function in our mouse model. We demonstrated that A2a and A2b purinergic receptor antagonists, SCH58261 or PSB1115, respectively, rescued NAD⁺-mediated suppression of T cell proliferation and function. Combining IDO1 inhibition and A2a/A2b receptor blockade improved survival and boosted the antitumor immune signature in mice with IDO1 overexpressing ovarian cancer. These findings elucidate the downstream adaptive metabolic consequences of IDO1 blockade in ovarian cancers that may undermine antitumor T cell responses in the tumor microenvironment.

Multimetric feature selection for analyzing multicategory outcomes of colorectal cancer: random forest and multinomial logistic regression models

Colorectal cancer (CRC) is one of the most common cancers worldwide, and a leading cause of cancer deaths. Better classifying multicategory outcomes of CRC with clinical and omic data may help adjust treatment regimens based on individual's risk. Here, we selected the features that were useful for classifying four-category survival outcome of CRC using the clinical and transcriptomic data, or clinical, transcriptomic, microsatellite instability and selected oncogenic-driver data (all data) of TCGA. We also optimized multimetric feature selection to develop the best multinomial logistic regression (MLR) and random forest (RF) models that had the highest accuracy, precision, recall and F1 score, respectively. We identified 2073 differentially expressed genes of the TCGA RNASeq dataset. MLR overall outperformed RF in the multimetric feature selection. In both RF and MLR models, precision, recall and F1 score increased as the feature number increased and peaked at the feature number of 600-1000, while the models' accuracy remained stable. The best model was the MLR one with 825 features based on sum of squared coefficients using all data, and attained the best accuracy of 0.855, F1 of 0.738 and precision of 0.832, which were higher than those using clinical and transcriptomic data. The top-ranked features in the MLR model of the best performance using clinical and transcriptomic data were different from those using all data. However, pathologic staging, HBS1L, TSPYL4, and TP53TG3B were the overlapping top-20 ranked features in the best models using clinical and transcriptomic, or all data. Thus, we developed a multimetric feature-selection based MLR model that outperformed RF models in classifying four-category outcome of CRC patients. Interestingly, adding microsatellite instability and oncogenic-driver data to clinical and transcriptomic data improved models' performances. Precision and recall of tuned algorithms may change significantly as the feature number changes, but accuracy appears not sensitive to these changes.

COX-2 inhibitors decrease expression of PD-L1 in colon tumors and increase the influx of Type I tumor infiltrating lymphocytes

Colon cancer is initiated under inflammatory conditions associated with upregulation of immune checkpoint proteins. We evaluated immune modulation induced by non-steroidal anti-inflammatory agents used for colon cancer prevention. Both celecoxib and naproxen inhibited polyp growth in APC Min mice. Treatment of mice with either drug significantly decreased PD-L1 expression on polyps in a dose dependent manner (p<0.0001 for both). The decrease in PD-L1 was associated with an influx of CD8+ T-cells into polyps (p<0.0001, celecoxib; p=0.048, naproxen) compared to lesions from untreated animals and correlated with disease control. Naproxen is a nonselective inhibitor of both COX-1 and COX-2, and we questioned the role of the different cyclooxygenases in PD-L1 regulation. Silencing either COX-2 or COX-1 RNA in the murine colon cancer cell line MC38, reduced PD-L1 expression by 86% in COX-2-silenced cells (p<0.0001) while there was little effect with COX-1 siRNA compared to control. Naproxen could inhibit the growth of MC38 in vivo. Naproxen treated mice demonstrated a significant reduction in MC38 growth as compared to control (p<0001). Both Tbet+ CD4 and CD8 tumor infiltrating T-cells (TIL) were significantly increased (p=0.04 and p=0.038 respectively) without a concurrent increase in GATA3+ TIL (p>0.05). CD8+ TIL highly expressed the activation marker, CD69. Not only was PD-L1 expression decreased on tumors, but LAG3+CD8+ T-cells and PD-1 and LAG3 expression on T-regulatory cells was also reduced (p=0.008 and p=0.002 respectively). These data demonstrate COX-2 inhibitors significantly decrease PD-L1 in colonic lesions and favorably impact the phenotype of tumor infiltrating lymphocytes to control tumor growth.

Translational Advances in Cancer Prevention Agent Development (TACPAD) Virtual Workshop on Immunomodulatory Agents: Report

The National Cancer Institute (NCI) Division of Cancer Prevention (DCP) convened the "Translational Advances in Cancer Prevention Agent Development (TACPAD) Workshop on Immunomodulatory Agents" as a virtual 2-day workshop on September 13 to 14, 2021. The main goals of this workshop were to foster the exchange of ideas and potentially new collaborative interactions among leading cancer immunoprevention researchers from basic and clinical research and highlight new and emerging trends in immunoprevention. The workshop included an overview of the mechanistic classes of immunomodulatory agents and three sessions covering the gamut from preclinical to clinical studies. The workshop convened individuals working in immunology and cancer prevention to discuss trends in discovery and development of immunomodulatory agents individually and in combination with other chemopreventive agents or vaccines.

Breast cancer vaccines for treatment and prevention

Breast cancer is immunogenic and a variety of vaccines have been designed to boost immunity directed against the disease. The components of a breast cancer vaccine, the antigen, the delivery system, and the adjuvant, can have a significant impact on vaccine immunogenicity. There have been numerous immunogenic proteins identified in all subtypes of breast cancer. The majority of these antigens are weakly immunogenic nonmutated tumor-associated proteins. Mutated proteins and neoantigen epitopes are found only in a small minority of patients and are enriched in the triple negative subtype. Several vaccines have advanced to large randomized Phase II or Phase III clinical trials. None of these trials met their primary endpoint of either progression-free or overall survival. Despite these set-backs investigators have learned important lessons regarding the clinical application of breast cancer vaccines from the type of immune response needed for tumor eradication, Type I T-cell immunity, to the patient populations most likely to benefit from vaccination. Many therapeutic breast cancer vaccines are now being tested in combination with other forms of immune therapy or chemotherapy and radiation. Breast cancer vaccines as single agents are now studied in the context of the prevention of relapse or development of disease. Newer approaches are designing vaccines to prevent breast cancer by intercepting high-risk lesions such as ductal carcinoma in situ to limit the progression of these tumors to invasive cancer. There are also several efforts to develop vaccines for the primary prevention of breast cancer by targeting antigens expressed during breast cancer initiation.

Pembrolizumab with low-dose carboplatin for recurrent platinum-resistant ovarian, fallopian tube, and primary peritoneal cancer: survival and immune correlates

Background

Anti-programmed death 1 (PD1)/programmed cell death ligand 1 (PD-L1) therapies have shown modest activity as monotherapy in recurrent ovarian cancer. Platinum chemotherapies induce T-cell proliferation and enhance tumor recognition. We assessed activity and safety of pembrolizumab with carboplatin in recurrent platinum-resistant ovarian cancer.

Patients and methods

This phase I/II, single-arm clinical trial studied concurrent carboplatin and pembrolizumab in recurrent platinum-resistant ovarian, fallopian tube, and primary peritoneal cancer. Primary platinum refractory patients were excluded. Patients were treated after progression on subsequent non-platinum systemic therapy after becoming platinum resistant or refractory. Pembrolizumab 200 mg was given on day 1 and carboplatin area under the curve 2 on days 8 and 15 of a 3-week cycle until progression. Imaging was assessed by blinded independent review. PD-L1 expression was assessed by immunohistochemistry. Flow cytometry on peripheral blood mononuclear cells was performed for CD3, CD4, CD8, PD1, CTLA4 and Ki67.

Results

The most common treatment-related adverse events were lymphopenia (18%) and anemia (9%) with most being grade 1 or 2 (93%). Of 29 patients treated, 23 patients were evaluable for best objective response: 10.3% (95% CI 2.2 to 27.4) had partial response (PR), 51.7% (95% CI 32.5 to 70.6) had stable disease (SD). 56.5% of patients had decreases in target lesions from baseline. All PD-L1-positive patients achieved PR (3/7, 42.8%) or SD (4/7, 57.2%). Median progression-free survival was 4.63 months (95% CI 4.3 to 4.96). Median OS was 11.3 months (95% CI 6.094 to 16.506). Peripheral CD8+PD1+Ki67+ T cells expanded after 3 (p=0.0015) and 5 (p=0.0023) cycles. CTLA4+PD1+CD8+ T cells decreased through the course of treatment up to the 12th cycle (p=0.004). When stratified by ratio of peripheral CD8+PD1+Ki67+ T cells to tumor burden at baseline, patients with a ratio ≥0.0375 who had a significantly longer median OS of 18.37 months compared with those with a ratio <0.0375 who had a median OS of 8.72 months (p=0.0099). No survival advantage was seen with stratification by tumor burden alone (p=0.24) or by CD8+PD1+Ki67+ T cells alone (p=0.53).

Conclusions

Pembrolizumab with carboplatin was well-tolerated and active in recurrent platinum-resistant ovarian cancer. A ratio of peripheral T-cell exhaustion to radiographic tumor burden may identify patients more likely to benefit from this chemoimmunotherapy.

Trial registration number

NCT03029598.

Immunization with a Plasmid DNA Vaccine Encoding the N-Terminus of Insulin-like Growth Factor Binding Protein-2 in Advanced Ovarian Cancer Leads to High-level Type I Immune Responses

BACKGROUND

Cancer vaccines targeting nonmutated proteins elicit limited type I T-cell responses and can generate regulatory and type II T cells. Class II epitopes that selectively elicit type I or type II cytokines can be identified in nonmutated cancer-associated proteins. In mice, a T-helper I (Th1) selective insulin-like growth factor binding protein-2 (IGFBP-2) N-terminus vaccine generated high levels of IFNγ secreting T cells, no regulatory T cells, and significant antitumor activity. We conducted a phase I trial of T-helper 1 selective IGFBP-2 vaccination in patients with advanced ovarian cancer.

METHODS

Twenty-five patients were enrolled. The IGFBP-2 N-terminus plasmid-based vaccine was administered monthly for 3 months. Toxicity was graded by NCI criteria and antigen-specific T cells measured by IFNγ/IL10 ELISPOT. T-cell diversity and phenotype were assessed.

RESULTS

The vaccine was well tolerated, with 99% of adverse events graded 1 or 2, and generated high levels of IGFBP-2 IFNγ secreting T cells in 50% of patients. Both Tbet⁺ CD4 (P = 0.04) and CD8 (P = 0.007) T cells were significantly increased in immunized patients. There was no increase in GATA3⁺ CD4 or CD8, IGFBP-2 IL10 secreting T cells, or regulatory T cells. A significant increase in T-cell clonality occurred in immunized patients (P = 0.03, pre- vs. post-vaccine) and studies showed the majority of patients developed epitope spreading within IGFBP-2 and/or to other antigens. Vaccine nonresponders were more likely to have preexistent IGFBP-2 specific immunity and demonstrated defects in CD4 T cells, upregulation of PD-1, and downregulation of genes associated with T-cell activation, after immunization.

CONCLUSIONS

IGFBP-2 N-terminus Th1 selective vaccination safely induces type I T cells without evidence of regulatory responses.

Multi-Epitope-Based Vaccines for Colon Cancer Treatment and Prevention

Background

Overexpression of nonmutated proteins involved in oncogenesis is a mechanism by which such proteins become immunogenic. We questioned whether overexpressed colorectal cancer associated proteins found at higher incidence and associated with poor prognosis could be effective vaccine antigens. We explored whether vaccines targeting these proteins could inhibit the development of intestinal tumors in the azoxymethane (AOM)-induced colon model and APC Min mice.

Methods

Humoral immunity was evaluated by ELISA. Web-based algorithms identified putative Class II binding epitopes of the antigens. Peptide and protein specific T-cells were identified from human peripheral blood mononuclear cells using IFN-gamma ELISPOT. Peptides highly homologous between mouse and man were formulated into vaccines and tested for immunogenicity in mice and in vivo tumor challenge. Mice treated with AOM and APC Min transgenic mice were vaccinated and monitored for tumors.

Results

Serum IgG for CDC25B, COX2, RCAS1, and FASCIN1 was significantly elevated in colorectal cancer patient sera compared to volunteers (CDC25B p=0.002, COX-2 p=0.001, FASCIN1 and RCAS1 p<0.0001). Epitopes predicted to bind to human class II MHC were identified for each protein and T-cells specific for both the peptides and corresponding recombinant protein were generated from human lymphocytes validating these proteins as human antigens. Some peptides were highly homologous between mouse and humans and after immunization, mice developed both peptide and protein specific IFN-γ-secreting cell responses to CDC25B, COX2 and RCAS1, but not FASCIN1. FVB/nJ mice immunized with CDC25B or COX2 peptides showed significant inhibition of growth of the syngeneic MC38 tumor compared to control (p<0.0001). RCAS1 peptide vaccination showed no anti-tumor effect. In the prophylactic setting, after immunization with CDC25B or COX2 peptides mice treated with AOM developed significantly fewer tumors as compared to controls (p<0.0002) with 50% of mice remaining tumor free in each antigen group. APC Min mice immunized with CDC25B or COX2 peptides developed fewer small bowel tumors as compared to controls (p=0.01 and p=0.02 respectively).

Conclusions

Immunization with CDC25B and COX2 epitopes consistently suppressed tumor development in each model evaluated. These data lay the foundation for the development of multi-antigen vaccines for the treatment and prevention of colorectal cancer.

Society for Immunotherapy of Cancer (SITC) clinical practice guideline on immunotherapy for the treatment of breast cancer

Breast cancer has historically been a disease for which immunotherapy was largely unavailable. Recently, the use of immune checkpoint inhibitors (ICIs) in combination with chemotherapy for the treatment of advanced/metastatic triple-negative breast cancer (TNBC) has demonstrated efficacy, including longer progression-free survival and increased overall survival in subsets of patients. Based on clinical benefit in randomized trials, ICIs in combination with chemotherapy for the treatment of some patients with advanced/metastatic TNBC have been approved by the United States (US) Food and Drug Administration (FDA), expanding options for patients. Ongoing questions remain, however, about the optimal chemotherapy backbone for immunotherapy, appropriate biomarker-based selection of patients for treatment, the optimal strategy for immunotherapy treatment in earlier stage disease, and potential use in histological subtypes other than TNBC. To provide guidance to the oncology community on these and other important concerns, the Society for Immunotherapy of Cancer (SITC) convened a multidisciplinary panel of experts to develop a clinical practice guideline (CPG). The expert panel drew upon the published literature as well as their clinical experience to develop recommendations for healthcare professionals on these important aspects of immunotherapeutic treatment for breast cancer, including diagnostic testing, treatment planning, immune-related adverse events (irAEs), and patient quality of life (QOL) considerations. The evidence-based and consensus-based recommendations in this CPG are intended to give guidance to cancer care providers treating patients with breast cancer.

A grant-based experiment to train clinical investigators: the AACR/ASCO methods in clinical cancer research workshop

To address the need for clinical investigators in oncology, AACR and ASCO established the Methods in Clinical Cancer Research Workshop (MCCRW). The workshop's objectives were to: (1) provide training in the methods, design, and conduct of clinical trials; (2) ensure that clinical trials met federal and international ethical guidelines; (3) evaluate the effectiveness of the workshop; and (4) create networking opportunities for young investigators with mentoring senior faculty. Educational methods included: (1) didactic lectures; (2) Small Group Discussion Sessions; (3) Protocol Development Groups; (4) one-on-one mentoring. Learning focused on the development of an IRB-ready protocol, which was submitted on the last day of the workshop. Evaluation methods included: (1) pre- and post-workshop tests; (2) students' workshop evaluations; (3) faculty's ratings of protocol development; (4) students' productivity in clinical research after the workshop; (5) an independent assessment of the workshop. From 1996-2014, 1932 students from diverse backgrounds attended the workshop. There was a significant improvement in the students' level of knowledge from the pre- to the post-workshop exams (p < 0.001). Across the classes, student evaluations were very favorable. At the end of the workshop, faculty rated 92-100% of the students' protocols as ready for IRB submission. Intermediate and long-term follow-ups indicated that more than 92% of students were actively involved in patientrelated research, and 66% had implemented five or more protocols. This NCI-sponsored MCCRW has had a major impact on the training of clinicians in their ability to design and implement clinical trials in cancer research.

Abstract 1556: Retinoid X receptor agonists enhances Th1 antigen-specific and polyfunctional T cells with the HER2-IGFBP2-IGF1R vaccine

Bexarotene and 9cUAB30 are highly selective oral retinoid X receptor (RXR) agonists with anti-proliferative activity in breast cancer. We have demonstrated that bexarotene enhances efficacy of a multi-antigen vaccine to prevent breast cancer in the TgMMTV-neu model and increases CD8 T-cell tumor infiltration. We further have shown that RXRα expression is in 24.9±13% of macrophages, 38.6 ±14% of plasmacytic dendritic cells (pDC), and 33.1 ± 16% of monocytic dendritic cells (mDC). Furthermore, the RXR agonists increased Th1 pDC and mDC. We therefore evaluated whether RXR agonists could enhance the vaccine antigen-specific immunogenicity and polyfunctional T cells in the transgenic mouse mammary tumor model TgMMTV-neu. Vaccination with the 150 µg HER2-IGFBP2-IGF1R vaccine and 5 ug GMCSF adjuvant every 2 weeks for four doses significantly increased antigen-specific IFN-γ T cells, but not antigen-specific IL10 T cells, as compared to control vaccination with empty vector. Interestingly, daily oral administration of 30 mg/kg bexarotene for 5 days prior to the HER2-IGFBP2-IGF1R vaccination series increased the IFN-γ immune responses to HER2, IGFBP2, and IGF1R by 1.2, 2.4 and 2.2 fold, respectively, as compared to the HER2-IGFBP2-IGF1R vaccine alone. Daily administration of a higher dose (200 mg/kg) 9cUAB30 for 5 days prior to the HER2-IGFBP2-IGF1R vaccination series increased the IFN-γ immune responses to HER2, IGFBP2, and IGF1R by 2.0, 2.3 and 1.7 fold, respectively, as compared to the HER2-IGFBP2-IGF1R vaccine alone. Control vaccination with either 9cUAB30 or bexarotene had no impact on antigen-specific IFN-γ T cell response. Type I DCs are important for producing polyfunctional CD4+ T cells that release not only IFN-γ but also TNF-α and IL-2. Polyfunctional T cells induce a longer lasting and more effective immune response in vaccines both for infectious diseases and cancer. We demonstrated the addition of bexarotene or 9cUAB30 increased antigen-specific polyfunctional T cells in the TgMMTV-neu (n=15 mice) transgenic mouse mammary tumor model while vaccination alone did not. There were an average of 1.3±0.2% antigen-specific CD4 polyfunctional T cells and 2.7±0.7 antigen-specific CD8 polyfunctional T cells with empty vector and vehicle control (sesame oil). HER2-IGFBP2-IGF1R vaccination following 30 mg/kg bexarotene treatment increased polyfunctional T cells to an average of 6.1±2.0% antigen-specific CD4 polyfunctional T cells (p=0.07) and 20.3±4.1% antigen-specific CD8 polyfunctional T cells (p=0.0003). HER2-IGBP2-IGF1R vaccination after 200 mg/kg 9cUAB30 increased antigen-specific polyfunctional T cells to 7.6±2.0% (p=0.01) and antigen-specific CD8 polyfunctional T cells to 17.6±4.1% (p=0.003). These data indicate that RXR agonists have an immunostimulatory role with multi-antigen cancer vaccines and may augment the anti-tumor activity of vaccines.

Citation Format: Sasha Elizabeth Stanton, Erin Rodmaker, Nicholas Drovetto, Lauren Corulli, Flonia Levy, Venkatram Atigadda, Clinton Grubbs, Romaine Fernando, Shizuko Sei, Mary L. Disis. Retinoid X receptor agonists enhances Th1 antigen-specific and polyfunctional T cells with the HER2-IGFBP2-IGF1R vaccine [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1556.

Final report and long-term outcomes: Phase I trial of a HER2 intracellular plasmid-based vaccine in HER2+ advanced stage breast cancer

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Background: Vaccination with the intracellular domain (ICD) of HER2 in pre-clinical models is both immunogenic and protective against the development of mammary tumors. This study (NCT00436254) was designed to examine the safety and optimal immunogenic dose of a DNA-based vaccine encoding the HER2 ICD in subjects with HER2+ breast cancer. Methods: Sixty-six patients with stage III or IV HER2 + breast cancer in remission or with stable bone only disease were enrolled into three vaccine arms: 1 (10mcg dose of plasmid), 2 (100mcg) and 3 (500mcg). Vaccines were administered i.d. monthly for three immunizations. Endpoints included safety and optimal dose. HER2 specific IFN-gamma immune responses were evaluated and DNA persistence at the vaccine site was assessed. Toxicity and clinical outcomes were followed for 10 years. Results: The majority of vaccine-related toxicity was grade 1 (89%) and grade 2 (11%) and was not significantly different between the three dose arms. All Arms developed HER2 ICD immunity after vaccination, however, patients in Arm 2 and Arm 3 had significantly better immune responses (of higher magnitude and at most time points) than patients in Arm 1 (p=0.003 and p<0.001, respectively) after adjusting for baseline factors. At 60 weeks, the number of patients who maintained the greatest fold-difference in HER2 ICD immune responses from their baseline was highest in Arm 2 (73%) when compared to Arm 1 (47%) and Arm 3 (45%). Associations between ICD responses and plasmid DNA persistence at the vaccine site were estimated via linear regression models. HER ICD immunity after the end of immunizations, relative to baseline, was significantly lower in patients with DNA persistence at week 16 compared to those without persistence (p=0.02). Patients at the highest dose demonstrated the greatest incidence of plasmid persistence (92%) as compared to 33% in Arm 1 and 10% in Arm 2. The median time of follow-up was 118.6 months (Arm 1), 99.7 months (Arm 2), and 73.5 months (Arm 3). The median OS and PFS has not been reached in any Arm and did not differ with respect to treatment arm (Log-rank p-value 0.36 for OS, and 0.63 for PFS). However, we observed a separation of Kaplan-Meier curves for OS from about 40 months and curves for PFS from about 30 months, and the separation maintained until the end of the study for Arm 2 versus Arm 1 and Arm 3. One patient in Arm 2 developed lymphocytic colitis 2.2 years from enrollment deemed possibly related to vaccination. Conclusions: An intermediate dose (100mcg) of vaccine was immunogenic and associated with persistence of immunity at 60 weeks. A randomized phase II trial of the HER2 ICD plasmid-based vaccine in the neoadjuvant setting is in development. Clinical trial information: NCT00436254.

Tumor-associated autoantibodies from mouse breast cancer models are found in serum of breast cancer patients

B cell responses to tumor antigens occur early in breast tumors and may identify immunogenic drivers of tumorigenesis. Sixty-two candidate antigens were identified prior to palpable tumor development in TgMMTV-neu and C3(1)Tag transgenic mouse mammary tumor models. Five antigens (VPS35, ARPC2, SERBP1, KRT8, and PDIA6) were selected because their decreased expression decreased survival in human HER2 positive and triple negative cell lines in a siRNA screen. Vaccination with antigen-specific epitopes, conserved between mouse and human, inhibited tumor growth in both transgenic mouse models. Increased IgG autoantibodies to the antigens were elevated in serum from women with ductal carcinoma in situ (DCIS) and invasive breast cancer (IBC). The autoantibodies differentiated women with DCIS from control with AUC 0.93 (95% CI 0.88-0.98, p < 0.0001). The tumor antigens identified early in the development of breast cancer in mouse mammary tumor models were conserved in human disease, and potentially identify early diagnostic markers in human breast tumors.

Differentiation and Regulation of TH Cells: A Balancing Act for Cancer Immunotherapy

Current success of immunotherapy in cancer has drawn attention to the subsets of T_H cells in the tumor which are critical for activation of anti-tumor response either directly by themselves or by stimulating cytotoxic T cell activity. However, presence of immunosuppressive pro-tumorigenic T_H subsets in the tumor milieu further contributes to the complexity of regulation of T_H cell-mediated immune response. In this review, we present an overview of the multifaceted positive and negative effects of T_H cells, with an emphasis on regulation of different T_H cell subtypes by various immune cells, and how a delicate balance of contradictory signals can influence overall success of cancer immunotherapy. We focus on the regulatory network that encompasses dendritic cell-induced activation of CD4⁺ T_H1 cells and subsequent priming of CD8⁺ cytotoxic T cells, along with intersecting anti-inflammatory and pro-tumorigenic T_H2 cell activity. We further discuss how other tumor infiltrating immune cells such as immunostimulatory T_H9 and T_fh cells, immunosuppressive T_reg cells, and the duality of T_H17 function contribute to tip the balance of anti- vs pro-tumorigenic T_H responses in the tumor. We highlight the developing knowledge of CD4⁺ T_H1 immune response against neoantigens/oncodrivers, impact of current immunotherapy strategies on CD4⁺ T_H1 immunity, and how opposing action of T_H cell subtypes can be explored further to amplify immunotherapy success in patients. Understanding the nuances of CD4⁺ T_H cells regulation and the molecular framework undergirding the balancing act between anti- vs pro-tumorigenic T_H subtypes is critical for rational designing of immunotherapies that can bypass therapeutic escape to maximize the potential of immunotherapy.

Meeting Report: Translational Advances in Cancer Prevention Agent Development Meeting

The Division of Cancer Prevention of the National Cancer Institute (NCI) and the Office of Disease Prevention of the National Institutes of Health co-sponsored the Translational Advances in Cancer Prevention Agent Development Meeting on August 27 to 28, 2020. The goals of this meeting were to foster the exchange of ideas and stimulate new collaborative interactions among leading cancer prevention researchers from basic and clinical research; highlight new and emerging trends in immunoprevention and chemoprevention as well as new information from clinical trials; and provide information to the extramural research community on the significant resources available from the NCI to promote prevention agent development and rapid translation to clinical trials. The meeting included two plenary talks and five sessions covering the range from pre-clinical studies with chemo/immunopreventive agents to ongoing cancer prevention clinical trials. In addition, two NCI informational sessions describing contract resources for the preclinical agent development and cooperative grants for the Cancer Prevention Clinical Trials Network were also presented.