Anti-HER2 CD4(+) T-helper type 1 response is a novel immune correlate to pathologic response following neoadjuvant therapy in HER2-positive breast cancer

Ductal Carcinoma In Situ

In breast cancer (BC) pathogenesis models, normal cells acquire somatic mutations and there is a stepwise progression from high-risk lesions and ductal carcinoma in situ to invasive cancer. The precancer biology of mammary tissue warrants better characterization to understand how different BC subtypes emerge. Primary methods for BC prevention or risk reduction include lifestyle changes, surgery, and chemoprevention. Surgical intervention for BC prevention involves risk-reducing prophylactic mastectomy, typically performed either synchronously with the treatment of a primary tumor or as a bilateral procedure in high-risk women. Chemoprevention with endocrine therapy carries adherence-limiting toxicity.

Reviewing the significance of dendritic cell vaccines in interrupting breast cancer development

Breast cancer is a heterogeneous disease and is the most prevalent cancer in women. According to the U.S breast cancer statistics, about 1 in every 8 women develop an invasive form of breast cancer during their lifetime. Immunotherapy has been a significant advancement in the treatment of cancer with multiple studies reporting favourable patient outcomes by modulating the immune response to cancer cells. Here, we review the significance of dendritic cell vaccines in treating breast cancer patients. We discuss the involvement of dendritic cells and oncodrivers in breast tumorigenesis, highlighting the rationale for targeting oncodrivers and neoantigens using dendritic cell vaccine therapy. We review different dendritic cell subsets and maturation states previously used to develop vaccines and suggest the use of DC vaccines for breast cancer prevention. Further, we highlight that the intratumoral delivery of type 1 dendritic cell vaccines in breast cancer patients activates tumor antigen-specific CD4+ T helper cell type 1 (Th1) cells, promoting an anti-tumorigenic immune response while concurrently blocking pro-tumorigenic responses. In summary, this review provides an overview of the current state of dendritic cell vaccines in breast cancer highlighting the challenges and considerations necessary for an efficient dendritic cell vaccine design in interrupting breast cancer development.

Dendritic Cell Subpopulations Are Associated with Prognostic Characteristics of Breast Cancer after Neoadjuvant Chemotherapy-An Observational Study

Breast cancer (BC) is the most prevalent malignancy in women and researchers have strived to develop optimal strategies for its diagnosis and management. Neoadjuvant chemotherapy (NAC), which reduces tumor size, risk of metastasis and patient mortality, often also allows for a de-escalation of breast and axillary surgery. Nonetheless, complete pathological response (pCR) is achieved in no more than 40% of patients who underwent NAC. Dendritic cells (DCs) are professional antigen-presenting cells present in the tumor microenvironment. The multitude of their subtypes was shown to be associated with the pathological and clinical characteristics of BC, but it was not evaluated in BC tissue after NAC. We found that highe r densities of CD123+ plasmacytoid DCs (pDCs) were present in tumors that did not show pCR and had a higher residual cancer burden (RCB) score and class. They were of higher stage and grade and more frequently HER2-negative. The density of CD123+ pCDs was an independent predictor of pCR in the studied group. DC-LAMP+ mature DCs (mDCs) were also related to characteristics of clinical relevance (i.e., pCR, RCB, and nuclear grade), although no clear trends were identified. We conclude that CD123+ pDCs are candidates for a novel biomarker of BC response to NAC.

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.

Tumor-Infiltrating Lymphocytes and Immune Response in HER2-Positive Breast Cancer

Human epidermal growth factor receptor 2-positive (HER2-positive) breast cancer accounts for 15 to 25% of breast cancer cases. Although therapies based on the use of monoclonal anti-HER2 antibodies present clinical benefit for a subtype of patients with HER2-positive breast cancer, more than 50% of them are unresponsive to targeted therapies or they eventually relapse. In recent years, reactivation of the adaptive immune system in patients with solid tumors has emerged as a therapeutic option with great potential for clinical benefit. Since the approval of the first treatment directed against HER2 as a therapeutic target, the range of clinical options has expanded greatly, and, in this sense, cellular immunotherapy with T cells relies on the cytotoxicity generated by these cells, which ultimately leads to antitumor activity. Lymphocytic infiltration of tumors encompasses a heterogeneous population of immune cells within the tumor microenvironment that exhibits distinct patterns of immune activation and exhaustion. The prevalence and prognostic value of tumor-infiltrating lymphocyte (TIL) counts are associated with a favorable prognosis in HER2-positive breast cancers. This review discusses emerging findings that contribute to a better understanding of the role of immune infiltrates in HER2-positive breast cancer. In addition, it summarizes the most recent results in HER2-positive breast cancer immunotherapy and anticipates which therapeutic strategies could be applied in the immediate future.

Effector Th1 cells under PD-1 and CTLA-4 checkpoint blockade abrogate the upregulation of multiple inhibitory receptors and by-pass exhaustion

Immune checkpoint inhibitor (ICI) immunotherapy relies on the restoration of T-cell functions. The ICI receptors are not only found on exhausted T cells but also upregulated upon activation and reach high levels on effector T cells. In an ex vivo model, this study explored the consequences of PD-1 and cytotoxic T-lymphocyte antigen (CTLA-4) blockade applied during specific time frames of T-cell stimulation that coincide with distinct functional phases in type 1 helper T (Th1) cells. When applied at an early stimulation stage, the checkpoint blockade interfered with the upregulation of multiple inhibitory receptors such as PD-1, LAG3, TIM-3 and CTLA-4. Moreover, extension of the blockade period restricted the hyporesponsiveness in T cells. Alternatively, a short-term ICI treatment was advantageous when applied at late time frames of Th1 cell stimulation. Here, a transition phase from effector to exhausted state, which coincided with the late time frames of Th1 stimulation, was clearly determined together with the transcriptomics data demonstrating the initiation of significant alterations in metabolic pathways, genetic information processes, effector and exhaustion specific pathways. Applied in this transition phase, PD-1 and/or CTLA-4 blockade downregulated the inhibitory receptors which were already present on the effector Th1 cells, potentially through endocytic pathways. Therefore, the efficacy of ICI therapy was modulated by the functional status of T cells and can be improved by modifying the timing and duration of PD-1 and CTLA-4 blockade. In conclusion, the ICI therapy not only supports the reactivation of T cells but can also constrain de novo exhaustion.

Vaccines for immunoprevention of DNA mismatch repair deficient cancers

The development of cancer vaccines to induce tumor-antigen specific immune responses was sparked by the identification of antigens specific to or overexpressed in cancer cells. However, weak immunogenicity and the mutational heterogeneity in many cancers have dampened cancer vaccine successes. With increasing information about mutational landscapes of cancers, mutational neoantigens can be predicted computationally to elicit strong immune responses by CD8 +cytotoxic T cells as major mediators of anticancer immune response. Neoantigens are potentially more robust immunogens and have revived interest in cancer vaccines. Cancers with deficiency in DNA mismatch repair have an exceptionally high mutational burden, including predictable neoantigens. Lynch syndrome is the most common inherited cancer syndrome and is caused by DNA mismatch repair gene mutations. Insertion and deletion mutations in coding microsatellites that occur during DNA replication include tumorigenesis drivers. The induced shift of protein reading frame generates neoantigens that are foreign to the immune system. Mismatch repair-deficient cancers and Lynch syndrome represent a paradigm population for the development of a preventive cancer vaccine, as the mutations induced by mismatch repair deficiency are predictable, resulting in a defined set of frameshift peptide neoantigens. Furthermore, Lynch syndrome mutation carriers constitute an identifiable high-risk population. We discuss the pathogenesis of DNA mismatch repair deficient cancers, in both Lynch syndrome and sporadic microsatellite-unstable cancers. We review evidence for pre-existing immune surveillance, the three mechanisms of immune evasion that occur in cancers and assess the implications of a preventive frameshift peptide neoantigen-based vaccine. We consider both preclinical and clinical experience to date. We discuss the feasibility of a cancer preventive vaccine for Lynch syndrome carriers and review current antigen selection and delivery strategies. Finally, we propose RNA vaccines as having robust potential for immunoprevention of Lynch syndrome cancers.

Intratumoral delivery of dendritic cells plus anti-HER2 therapy triggers both robust systemic antitumor immunity and complete regression in HER2 mammary carcinoma

Background

Human epidermal growth factor receptor 2 (HER2) targeted antibodies in combination with chemotherapy has improved outcomes of HER2 positive (pos) breast cancer (BC) but toxicity of therapy remains a problem. High levels of tumor-infiltrating lymphocytes are associated with increased pathologic complete responses for patients treated with neoadjuvant therapy. Here we sought to investigate whether delivery of intratumoral (i.t.) multiepitope major histocompatibility complex (MHC) class II HER2 peptides-pulsed type I polarized dendritic cells (HER2-DC1) in combination with anti-HER2 antibodies without chemotherapy could enhance tumor regression by increasing anti-HER2 lymphocyte infiltration into the tumor.

Methods

BALB/c mice bearing orthotopic TUBO tumors, BALB/c mice bearing subcutaneous (s.c.) CT26 hHER2 tumors, or BALB-HER2/neu transgenic mice were all treated with i.t. or s.c. HER2-DC1, anti-HER2 antibodies, paclitaxel, T-DM1 or in combination. Immune response, host immune cells and effector function were analyzed using flow cytometry, interferon-γ ELISA and cytokine/chemokine arrays. The contributions of CD4⁺ and CD8⁺ T cells and antibody dependent cellular cytotoxicity (ADCC) were assessed using depleting antibodies and FcγR KO mice. Molecular changes were evaluated by immunohistochemistry and western blot.

Results

HER2-DC1 combined with anti-HER2 antibodies delivered i.t. compared to s.c. induced complete tumor regression in 75–80% of treated mice, with increased tumor infiltrating CD4⁺ and CD8⁺ T, B, natural killer T cells (NKT) and natural killer cells, and strong anti-HER2 responses in all HER2^pos BC models tested. The therapy caused regression of untreated distant tumors. Labeled HER2-DC1 migrated prominently into the distant tumor and induced infiltration of various DC subsets into tumors. HER2-DC1 i.t. combined with anti-HER2 antibodies displayed superior antitumor response compared to standard chemotherapy with anti-HER2 antibodies. Lasting immunity was attained which prevented secondary tumor formation. The presence of CD4⁺ and CD8⁺ T cells and ADCC were required for complete tumor regression. In the HER2^pos BC models, HER2-DC1 i.t. combined with anti-HER2 antibodies effectively diminished activation of HER2-mediated oncogenic signaling pathways.

Conclusions

HER2-DC1 i.t. with anti-HER2 antibodies mediates tumor regression through combined activation of T and B cell compartments and provides evidence that HER2-DC1 i.t. in combination with anti-HER2 antibodies can be tested as an effective alternative therapeutic strategy to current chemotherapy and anti-HER2 antibodies in HER2^pos BC.

No evidence of disease versus residual disease in long-term responders to first-line HER2-targeted therapy for metastatic breast cancer

BACKGROUND

Long-term response to HER2-targeted therapies is infrequent in metastatic breast cancer (MBC). We evaluated clinical characteristics of HER2-positive MBC patients with no evidence of disease (NED) vs residual disease (RES) experiencing long-term response to first-line HER2-targeted therapy.

METHODS

Patients receiving first-line chemotherapy-trastuzumab (CT) or taxane-trastuzumab-pertuzumab (THP) with response duration ≥2-fold higher than in phase II/III trials (CT [18.2 months]; THP [40.4 months]) were included. Clinical characteristics and radiographic review for NED or RES was evaluated by Cox-regression (hazard ratio; HR) or Kaplan-Meier (log-rank). Characteristics associated with NED were evaluated by logistic regression (Odds; OR).

RESULTS

From 01/2005-01/2016, N = 103 (4.6%) patients were identified. In multivariate analyses, NED (N = 46) showed improved progression-free (PFS) and overall survival (OS) [p < 0.001] versus RES (N = 57), with high 5-year PFS/OS for NED (93.2%/97.4%) relative to RES (10.6%/61.3%). Premenopausal status (p = 0.006), de-novo metastases (p = 0.002), and no palliative radiotherapy (p = 0.01) were associated with NED. Overall, 6/7 (85.7%) patients with NED were alive and disease-free after discontinuing HER2 treatment (≥1 year) versus 1/17 (5.9%) with RES.

CONCLUSIONS

Long-term responders with NED have better survival compared to RES. Premenopausal status and de novo metastatic disease are associated with NED. Prospective studies of HER2 therapy discontinuation with NED in MBC are warranted.

Intercepting Premalignant, Preinvasive Breast Lesions Through Vaccination

Breast cancer (BC) prevention remains the ultimate cost-effective method to reduce the global burden of invasive breast cancer (IBC). To date, surgery and chemoprevention remain the main risk-reducing modalities for those with hereditary cancer syndromes, as well as high-risk non-hereditary breast lesions such as ADH, ALH, or LCIS. Ductal carcinoma in situ (DCIS) is a preinvasive malignant lesion of the breast that closely mirrors IBC and, if left untreated, develops into IBC in up to 50% of lesions. Certain high-risk patients with DCIS may have a 25% risk of developing recurrent DCIS or IBC, even after surgical resection. The development of breast cancer elicits a strong immune response, which brings to prominence the numerous advantages associated with immune-based cancer prevention over drug-based chemoprevention, supported by the success of dendritic cell vaccines targeting HER2-expressing BC. Vaccination against BC to prevent or interrupt the process of BC development remains elusive but is a viable option. Vaccination to intercept preinvasive or premalignant breast conditions may be possible by interrupting the expression pattern of various oncodrivers. Growth factors may also function as potential immune targets to prevent breast cancer progression. Furthermore, neoantigens also serve as effective targets for interception by virtue of strong immunogenicity. It is noteworthy that the immune response also needs to be strong enough to result in target lesion elimination to avoid immunoediting as it may occur in IBC arising from DCIS. Overall, if the issue of vaccine targets can be solved by interrupting premalignant lesions, there is a potential to prevent the development of IBC.

Can Breast Implants Induce Breast Cancer Immunosurveillance? An Analysis of Antibody Response to Breast Cancer Antigen following Implant Placement

BACKGROUND

Women with cosmetic breast implants have significantly lower rates of subsequent breast cancer than the general population (relative risk, 0.63; 95 percent CI, 0.56 to 0.71). The authors hypothesize that breast implant-induced local inflammation stimulates immunosurveillance recognition of breast tumor antigen.

METHODS

Sera were collected from two cohorts of healthy women: women with long-term breast implants (i.e., breast implants for >6 months) and breast implant-naive women. Antibody responses to breast tumor antigens were tested by enzyme-linked immunosorbent assay and compared between cohorts by unpaired t test. Of the implant-naive cohort, nine women underwent breast augmentation, and antibody responses before and after implant placement were compared by paired t test.

RESULTS

Sera were collected from 104 women: 36 (34.6 percent) long-term breast implants and 68 (65.4 percent) implant-naive women. Women with long-term breast implants had higher antibody responses than implant-naive women to mammaglobin-A (optical density at 450 nm, 0.33 versus 0.22; p = 0.003) and mucin-1 (optical density at 450 nm, 0.42 versus 0.34; p = 0.02). There was no difference in antibody responses to breast cancer susceptibility gene 2, carcinoembryonic antigen, human epidermal growth factor receptor-2, or tetanus. Nine women with longitudinal samples preoperatively and 1 month postoperatively demonstrated significantly elevated antibody responses following implant placement to mammaglobin-A (mean difference, 0.13; p = 0.0002) and mucin-1 (mean difference 0.08; p = 0.02). There was no difference in postimplant responses to other breast tumor antigens, or tetanus.

CONCLUSIONS

Women with long-term breast implants have higher antibody recognition of mammaglobin-A and mucin-1. This study provides the first evidence of implant-related immune responses to breast cancer antigens.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, V.

Gut Microbiota Condition the Therapeutic Efficacy of Trastuzumab in HER2-Positive Breast Cancer

Emerging evidence indicates that gut microbiota affect the response to anticancer therapies by modulating the host immune system. In this study, we investigated the impact of gut microbiota on immune-mediated trastuzumab antitumor efficacy in preclinical models of HER2-positive breast cancer and in 24 patients with primary HER2-positive breast cancer undergoing trastuzumab-containing neoadjuvant treatment. In mice, the antitumor activity of trastuzumab was impaired by antibiotic administration or fecal microbiota transplantation from antibiotic-treated donors. Modulation of the intestinal microbiota was reflected in tumors by impaired recruitment of CD4⁺ T cells and granzyme B-positive cells after trastuzumab treatment. Antibiotics caused reductions in dendritic cell (DC) activation and the release of IL12p70 upon trastuzumab treatment, a mechanism that was necessary for trastuzumab effectiveness in our model. In patients, lower α-diversity and lower abundance of Lachnospiraceae, Turicibacteraceae, Bifidobacteriaceae, and Prevotellaceae characterized nonresponsive patients (NR) compared with those who achieved pathologic complete response (R), similar to antibiotic-treated mice. The transfer of fecal microbiota from R and NR into mice bearing HER2-positive breast cancer recapitulated the response to trastuzumab observed in patients. Fecal microbiota β-diversity segregated patients according to response and positively correlated with immune signature related to interferon (IFN) and NO2-IL12 as well as activated CD4⁺ T cells and activated DCs in tumors. Overall, our data reveal the direct involvement of the gut microbiota in trastuzumab efficacy, suggesting that manipulation of the gut microbiota is an optimal future strategy to achieve a therapeutic effect or to exploit its potential as a biomarker for treatment response. SIGNIFICANCE: Evidence of gut microbiota involvement in trastuzumab efficacy represents the foundation for new therapeutic strategies aimed at manipulating commensal bacteria to improve response in trastuzumab-resistant patients.See related commentary by Sharma, p. 1937 GRAPHICAL ABSTRACT: http://cancerres.aacrjournals.org/content/canres/81/8/2195/F1.large.jpg.

Subgroup analysis of nelipepimut-S plus GM-CSF combined with trastuzumab versus trastuzumab alone to prevent recurrences in patients with high-risk, HER2 low-expressing breast cancer

HER2-targeted therapy has not benefited patients with low levels of HER2 expression; however, combination therapy may be effective. Primary analysis of a phase IIb trial investigating the HER2-derived vaccine nelipepimut-S (NPS) did not benefit the intention-to-treat population, but subset analysis showed a benefit in triple-negative breast cancer (TNBC) patients. The subset analysis of this multicenter, randomized, single-blind, phase IIb trial identified significant improvement in 36-month disease-free survival (DFS) between NPS (n = 55) and placebo (n = 44) in TNBC (HR 0.25, p = 0.01) and those who express HLA-A24 (HR 0.41, p = 0.05). The TNBC cohort demonstrated improved 36-month DFS in those with HER2 1+ expression (HR 0.17, p = 0.01), HLA-A24 positivity (HR 0.08, p < 0.01), or in those who received neoadjuvant chemotherapy (HR 0.21, p < 0.01). NPS vaccination with trastuzumab was associated with improved 36-month DFS among patients with TNBC. The observed benefit to this high-risk subgroup warrants confirmation in a phase III trial.

Eliminating the breast cancer surgery paradigm after neoadjuvant systemic therapy: current evidence and future challenges

In patients with operable early breast cancer, neoadjuvant systemic treatment (NST) is a standard approach. Indications have expanded from downstaging of locally advanced breast cancer to facilitate breast conservation, to in vivo drug-sensitivity testing. The pattern of response to NST is used to tailor systemic and locoregional treatment, that is, to escalate treatment in nonresponders and de-escalate treatment in responders. Here we discuss four questions that guide our current thinking about 'response-adjusted' surgery of the breast after NST. (i) What critical diagnostic outcome measures should be used when analyzing diagnostic tools to identify patients with pathologic complete response (pCR) after NST? (ii) How can we assess response with the least morbidity and best accuracy possible? (iii) What oncological consequences may ensue if we rely on a nonsurgical-generated diagnosis of, for example, minimally invasive biopsy proven pCR, knowing that we may miss minimal residual disease in some cases? (iv) How should we design clinical trials on de-escalation of surgical treatment after NST?

Th1 cytokine interferon gamma improves response in HER2 breast cancer by modulating the ubiquitin proteasomal pathway

HER2 breast cancer (BC) remains a significant problem in patients with locally advanced or metastatic BC. We investigated the relationship between T helper 1 (Th1) immune response and the proteasomal degradation pathway (PDP), in HER2-sensitive and -resistant cells. HER2 overexpression is partially maintained because E3 ubiquitin ligase Cullin5 (CUL5), which degrades HER2, is frequently mutated or underexpressed, while the client-protective co-chaperones cell division cycle 37 (Cdc37) and heat shock protein 90 (Hsp90) are increased translating to diminished survival. The Th1 cytokine interferon (IFN)-γ caused increased CUL5 expression and marked dissociation of both Cdc37 and Hsp90 from HER2, causing significant surface loss of HER2, diminished growth, and induction of tumor senescence. In HER2-resistant mammary carcinoma, either IFN-γ or Th1-polarizing anti-HER2 vaccination, when administered with anti-HER2 antibodies, demonstrated increased intratumor CUL5 expression, decreased surface HER2, and tumor senescence with significant therapeutic activity. IFN-γ synergized with multiple HER2-targeted agents to decrease surface HER2 expression, resulting in decreased tumor growth. These data suggest a novel function of IFN-γ that regulates HER2 through the PDP pathway and provides an opportunity to impact HER2 responses through anti-tumor immunity.

Temporary blockade of interferon-γ ameliorates doxorubicin-induced cardiotoxicity without influencing the anti-tumor effect

Doxorubicin (DOX) is commonly used as an anti-cancer agent. However, its severe cardiotoxicity often makes it life threatening even long after DOX therapy during childhood. We recently reported interferon-γ (IFN-γ) necessary for DOX-induced acute cardiotoxicity in a p38 dependent way and, asked here for the potential of IFN-γ blockade to prevent DOX-induced chronic cardiotoxicity during tumor therapy. In our model system, mice without or with growing tumors repeatedly received DOX treatment. Simultaneous injection of anti-IFN-γ antibody R46-A2 with DOX to block IFN-γ signal efficiently protected the cardiac function of DOX treated recipients. Importantly, a single late injection of R46-A2 after DOX exposure also ameliorated DOX induced cardiac dysfunction in tumor-bearing mice. The anti-IFN-γ treatment did not affect the DOX-mediated tumor suppression effect and it left the main cellular immune response intact. Therefore, temporary blockade of IFN-γ may represent a novel strategy to ameliorate established DOX induced cardiotoxicity (DIC) or prevent its development in tumor therapy.

The Diagnostic Performance of Minimally Invasive Biopsy in Predicting Breast Pathological Complete Response After Neoadjuvant Systemic Therapy in Breast Cancer: A Meta-Analysis

Background: Neoadjuvant systemic therapy (NST) is commonly used in patients with early stage breast cancer before definitive surgery. The standard diagnostic approach for pathologic complete response (pCR) of the breast is breast surgery and pathologic examination. In recent years, several trials investigated the predictive value of image-guided minimally invasive biopsy (MIB) for breast pCR after NST. This study conducted a meta-analysis to evaluate the diagnostic accuracy of MIB.

Materials and Methods: We identified relevant research reports in online databases through February 2020. The Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2) tool was used to evaluate the quality of included trials. We extracted relevant data and constructed a 2 × 2 contingency table to analyze the predictive accuracy of MIB for breast pCR. Subgroup analyses and meta-regressions were also performed to investigate potential causes of heterogeneity.

Results: Nine trials (with 1,030 breast cancer patients) were included in this meta-analysis. The pooled sensitivity and specificity of MIB were 0.72 [95% confidence interval (CI): 0.61–0.81] and 0.99 (95% CI: 0.89–1.00), respectively. By combining relevant data, there were no significant differences in sensitivity or specificity among different molecular subtypes of breast cancer (P > 0.05). Subgroup analyses and meta-regressions implied that trials with responses not limited to clinical complete response (cCR) had a significantly higher accuracy of MIB than those with only cCR (RDOR: 7.65; 95% CI: 1.05–55.46; P = 0.046).

Conclusion: Current image-guided MIB methods are not accurate enough in terms of predicting breast pCR after NST. It is of utmost clinical importance to standardize the MIB procedure and incorporate other factors into the evaluation in order to improve the accuracy to an acceptable level.

HER2-LAMP vaccines effectively traffic to endolysosomal compartments and generate enhanced polyfunctional T cell responses that induce complete tumor regression

BACKGROUND

The advent of immune checkpoint blockade antibodies has demonstrated that effective mobilization of T cell responses can cause tumor regression of metastatic cancers, although these responses are heterogeneous and restricted to certain histologic types of cancer. To enhance these responses, there has been renewed emphasis in developing effective cancer-specific vaccines to stimulate and direct T cell immunity to important oncologic targets, such as the oncogene human epidermal growth factor receptor 2 (HER2), expressed in ~20% of breast cancers (BCs).

METHODS

In our study, we explored the use of alternative antigen trafficking through use of a lysosome-associated membrane protein 1 (LAMP) domain to enhance vaccine efficacy against HER2 and other model antigens in both in vitro and in vivo studies.

RESULTS

We found that inclusion of this domain in plasmid vaccines effectively trafficked antigens to endolysosomal compartments, resulting in enhanced major histocompatibility complex (MHC) class I and II presentation. Additionally, this augmented the expansion/activation of antigen-specific CD4+ and CD8+ T cells and also led to elevated levels of antigen-specific polyfunctional CD8+ T cells. Significantly, vaccination with HER2-LAMP produced tumor regression in ~30% of vaccinated mice with established tumors in an endogenous model of metastatic HER2+ BC, compared with 0% of HER2-WT vaccinated mice. This therapeutic benefit is associated with enhanced tumor infiltration of activated CD4+ and CD8+ T cells.

CONCLUSIONS

These data demonstrate the potential of using LAMP-based endolysosomal trafficking as a means to augment the generation of polyfunctional, antigen-specific T cells in order to improve antitumor therapeutic responses using cancer antigen vaccines.

Serum miR-222-3p as a Double-Edged Sword in Predicting Efficacy and Trastuzumab-Induced Cardiotoxicity for HER2-Positive Breast Cancer Patients Receiving Neoadjuvant Target Therapy

Background: We aimed to explore whether the expression of serum miR-222-3p might contribute to early prediction of therapeutic response, clinical outcomes, and adverse events for HER2-positive breast cancer patients receiving neoadjuvant therapy (NAT).

Methods: A total of 65 HER2-positive breast cancer patients receiving NAT were analyzed. The concentration of serum miR-222-3p was detected by quantitative real-time PCR. Logistic regression analysis was used to identify the association of serum miR-222-3p with pathological complete response (pCR). The relationship of serum miR-222-3p with disease-free survival (DFS) and overall survival (OS) was examined via log-rank test and Cox proportional hazards analysis. The ordered logistic regression was applied to evaluate the association between serum miR-222-3p and adverse events.

Results: The miR-222-3p low group was more likely to achieve pCR [odds ratio (OR) = 0.258, P = 0.043]. The interaction between miR-222-3p and presenting Ki67 level was also detected for pCR (OR = 49.230, P_interaction = 0.025). The miR-222-3p low group was correlated with superior DFS (P = 0.029) and OS (P = 0.0037). The expression of serum miR-222-3p was the independent protective factor for trastuzumab-induced cardiotoxicity (P < 0.05) and anemia (P = 0.013).

Conclusions: Serum miR-222-3p is the potential factor to predict pCR, survival benefit and trastuzumab-induced cardiotoxicity for HER2-positive breast cancer patients receiving NAT.

Janus or Hydra: The Many Faces of T Helper Cells in the Human Tumour Microenvironment

CD4+ T helper (T_H) cells are key regulators in the tumour immune microenvironment (TIME), mediating the adaptive immunological response towards cancer, mainly through the activation of cytotoxic CD8+ T cells. After antigen recognition and proper co-stimulation, naïve T_H cells are activated, undergo clonal expansion, and release cytokines that will define the differentiation of a specific effector T_H cell subtype. These different subtypes have different functions, which can mediate both anti- and pro-tumour immunological responses. Here, we present the dual role of T_H cells restraining or promoting the tumour, the factors controlling their homing and differentiation in the TIME, their influence on immunotherapy, and their use as prognostic indicators.

If we build it they will come: targeting the immune response to breast cancer

Historically, breast cancer tumors have been considered immunologically quiescent, with the majority of tumors demonstrating low lymphocyte infiltration, low mutational burden, and modest objective response rates to anti-PD-1/PD-L1 monotherapy. Tumor and immunologic profiling has shed light on potential mechanisms of immune evasion in breast cancer, as well as unique aspects of the tumor microenvironment (TME). These include elements associated with antigen processing and presentation as well as immunosuppressive elements, which may be targeted therapeutically. Examples of such therapeutic strategies include efforts to (1) expand effector T-cells, natural killer (NK) cells and immunostimulatory dendritic cells (DCs), (2) improve antigen presentation, and (3) decrease inhibitory cytokines, tumor-associated M2 macrophages, regulatory T- and B-cells and myeloid derived suppressor cells (MDSCs). The goal of these approaches is to alter the TME, thereby making breast tumors more responsive to immunotherapy. In this review, we summarize key developments in our understanding of antitumor immunity in breast cancer, as well as emerging therapeutic modalities that may leverage that understanding to overcome immunologic resistance.

Evaluation of the Predictive Role of Tumor Immune Infiltrate in Patients with HER2-Positive Breast Cancer Treated with Neoadjuvant Anti-HER2 Therapy without Chemotherapy

PURPOSE

Tumor-infiltrating lymphocytes (TIL) are associated with benefit to trastuzumab and chemotherapy in patients with early-stage HER2⁺ breast cancer. The predictive value of TILs, TIL subsets, and other immune cells in patients receiving chemotherapy-sparing lapatinib plus trastuzumab treatment is unclear.Experimental Design: Hematoxylin and eosin-stained slides (n = 59) were used to score stromal (s-)TILs from pretreatment biopsies of patients enrolled in the neoadjuvant TBCRC006 trial of 12-week lapatinib plus trastuzumab therapy (plus endocrine therapy for ER⁺ tumors). A 60% threshold was used to define lymphocyte-predominant breast cancer (LPBC). Multiplexed immunofluorescence (m-IF) staining (CD4, CD8, CD20, CD68, and FoxP3) and multispectral imaging were performed to characterize immune infiltrates in single formalin-fixed paraffin-embedded slides (n = 33).

RESULTS

The pathologic complete response (pCR) rate was numerically higher in patients with LPBC compared with patients with non-LPBC (50% vs. 19%, P = 0.057). Unsupervised hierarchical clustering of the five immune markers identified two patient clusters with different responses to lapatinib plus trastuzumab treatment (pCR = 7% vs. 50%, for cluster 1 vs. 2 respectively; P = 0.01). In multivariable analysis, cluster 2, characterized by high CD4⁺, CD8⁺, CD20⁺ s-TILs, and high CD20⁺ intratumoral TILs, was independently associated with a higher pCR rate (P = 0.03). Analysis of single immune subpopulations revealed a significant association of pCR with higher baseline infiltration by s-CD4, intratumoral (i-) CD4, and i-CD20⁺ TILs.

CONCLUSIONS

LPBC was marginally associated with higher pCR rate than non-LPBC in patients with lapatinib plus trastuzumab treated HER2⁺ breast cancer. Quantitative assessment of the immune infiltrate by m-IF is feasible and may help correlate individual immune cell subpopulations and immune cell profiles with treatment response.

T-helper 1-type cytokines induce apoptosis and loss of HER-family oncodriver expression in murine and human breast cancer cells

A recent neoadjuvant vaccine trial for early breast cancer induced strong Th1 immunity against the HER-2 oncodriver, complete pathologic responses in 18% of subjects, and for many individuals, dramatically reduced HER-2 expression on residual disease. To explain these observations, we investigated actions of Th1 cytokines (TNF-α and IFN-γ) on murine and human breast cancer cell lines that varied in the surface expression of HER-family receptor tyrosine kinases. Breast cancer lines were broadly sensitive to the combination of IFN-γ and TNF-α, as evidenced by lower metabolic activity, lower proliferation, and enhanced apoptosis, and in some cases a reversible inhibition of surface expression of HER proteins. Apoptosis was accompanied by caspase-3 activation. Furthermore, the pharmacologic caspase-3 activator PAC-1 mimicked both the killing effects and HER-2-suppressive activities of Th1 cytokines, while a caspase 3/7 inhibitor could prevent cytokine-induced HER-2 loss. These studies demonstrate that many in vivo effects of vaccination (apparent tumor cell death and loss of HER-2 expression) could be replicated in vitro using only the principle Th1 cytokines. These results are consistent with the notion that IFN-γ and TNF-α work in concert to mediate many biological effects of therapeutic vaccination through the induction of a caspase 3-associated cellular death mechanism.

Biomarkers for Evaluating the Inflammation Status in Patients with Cancer

Inflammation can be a causative factor for carcinogenesis or can result from a consequence of cancer progression. Moreover, cancer therapeutic interventions can also induce an inflammatory response. Various inflammatory parameters are used to assess the inflammatory status during cancer treatment. It is important to select the most optimal biomarker among these parameters. Additionally, suitable biomarkers must be examined if there are no known parameters. We briefly reviewed the published literature for the use of inflammatory parameters in the treatment of patients with cancer. Most studies on inflammation evaluated the correlation between host characteristics, effect of interventions, and clinical outcomes. Additionally, the levels of C-reactive protein, albumin, lymphocytes, and platelets were the most commonly used laboratory parameters, either independently or in combination with other laboratory parameters and clinical characteristics. Furthermore, the immune parameters are classically examined using flow cytometry, immunohistochemical staining, and enzyme-linked immunosorbent assay techniques. However, gene expression profiling can aid in assessing the overall peri-interventional immune status. The checklists of guidelines, such as STAndards for Reporting of Diagnostic accuracy and REporting recommendations for tumor MARKer prognostic studies should be considered when designing studies to investigate the inflammatory parameters. Finally, the data should be interpreted after adjusting for clinically important variables, such as age and cancer stage.

Inflammatory Breast Cancer: a Separate Entity

PURPOSE OF REVIEW

Inflammatory breast cancer (IBC) is an uncommon but highly aggressive subtype of breast cancer that contributes significantly to breast cancer-related mortality. In this review, we provide an overview of the clinical and molecular characteristics of IBC, and highlight some areas of need for ongoing research.

RECENT FINDINGS

The disease is characterized by florid tumor emboli that obstruct dermal lymphatics, leading to swelling and inflammation of the affected breast. Recent studies have focused on tumor cell intrinsic features, such as signaling through pathways involved in growth and stem-like behavior, as well as extrinsic features, such as the immune system, that can be leveraged to develop new potential therapies. Key efforts have led to an increase in awareness of the disease as well as new insights into IBC pathogenesis. However, there is a strong need for new therapies designed specifically for IBC, and many unanswered questions remain.

Interaction of host immunity with HER2-targeted treatment and tumor heterogeneity in HER2-positive breast cancer

Growing evidence suggests a clear role of the host immune system in HER2+ breast cancer. In addition, HER2+ breast cancer is generally considered more immunogenic than hormone receptor-positive (HR+)/HER2-, and specific molecular HER2+ subgroups (e.g. HER2-enriched disease) are more immunogenic than others (e.g. Luminal A or B). From a clinical perspective, the immune system plays a relevant prognostic role in HER2+ breast cancer and contributes to the therapeutic effects of trastuzumab. However, as more HER2-targeted agents become available, a better understanding of the role played by the immune system in modulating therapy response to different agents will be needed. Furthermore, the recent introduction in oncology of immune checkpoint inhibitors capable of unleashing anti-tumor immune response opens new possibilities for therapeutic combinations in HER2+ breast cancer. Here, we review the current pre-clinical and clinical data on the interplay between the immune system and HER2+ breast cancer, focusing on different HER2-targeted treatments and the biological heterogeneity that exists within HER2+ disease. Finally, we discuss new therapeutic approaches exploiting the immune system to increase activity or revert resistance to HER2-targeted agents.

Predictive and prognostic value of circulating blood lymphocyte subsets in metastatic breast cancer

The treatment of breast cancer (BC) has improved greatly in recent years, however, the limitations of current therapeutic modalities underscore the need to define new prognostic tools and develop highly targeted therapies. The aims of the present study were to explore the effects of circulating blood lymphocyte subsets on the survival of metastatic breast cancer (MBC) patients and to evaluate their predictive and prognostic value. The clinical data of 482 patients with MBC were retrospectively analyzed, and patients were grouped according to molecular types of BC. The distribution of peripheral blood lymphocyte subsets at the time of first metastasis was examined by flow cytometry, and the distribution of lymphocyte subsets in each group was categorized into ''high or low'' subgroups using the upper quartile point as the cutoff. The relationship between the distribution of lymphocyte subsets and progression-free survival (PFS) as well as overall survival (OS) was evaluated in diverse molecular MBCs. In multivariate analysis, CD4⁺ was a negative independent predictor of PFS (hazard ratio [HR] = 0.538, 95% confidence interval [CI] = 0.313-0.926, P = 0.025) and CD3⁺ was a poor independent prognostic factor for OS (HR = 0.437, 95% CI = 0.248-0.772, P = 0.004) in the human epidermal growth factor receptor 2 (HER2)-positive group. Neither the CD8⁺ , CD19⁺ , and CD56⁺ lymphocyte subsets nor the CD4⁺ /CD8⁺ ratio in peripheral blood was significant predictive or prognostic factors. In conclusion, higher circulating levels of CD4⁺ and CD3⁺ at first diagnosis in HER2-overexpressing MBC were significantly associated with worse survival outcomes. Low levels of plasma CD4⁺ and CD3⁺ were associated with increased anti-HER2 benefit in HER2-positive MBC. The present results indicate that these factors can be used as predictive and prognostic indicators of the outcome of patients with MBC.

Early immune modulation by single-agent trastuzumab as a marker of trastuzumab benefit

BACKGROUND

Optimising the selection of HER2-targeted regimens by identifying subsets of HER2-positive breast cancer (BC) patients who need more or less therapy remains challenging. We analysed BC samples before and after treatment with 1 cycle of trastuzumab according to the response to trastuzumab.

METHODS

Gene expression profiles of pre- and post-treatment tumour samples from 17 HER2-positive BC patients were analysed on the Illumina platform. Tumour-associated immune pathways and blood counts were analysed with regard to the response to trastuzumab. HER2-positive murine models with differential responses to trastuzumab were used to reproduce and better characterise these data.

RESULTS

Patients who responded to single-agent trastuzumab had basal tumour biopsies that were enriched in immune pathways, particularly the MHC-II metagene. One cycle of trastuzumab modulated the expression levels of MHC-II genes, which increased in patients who had a complete response on treatment with trastuzumab and chemotherapy. Trastuzumab increased the MHC-II-positive cell population, primarily macrophages, only in the tumour microenvironment of responsive mice. In patients who benefited from complete trastuzumab therapy and in mice that harboured responsive tumours circulating neutrophil levels declined, but this cell subset rose in nonresponsive tumours.

CONCLUSIONS

Short treatment with trastuzumab induces local and systemic immunomodulation that is associated with clinical outcomes.

Predicting the response to neoadjuvant therapy for early-stage breast cancer: tumor-, blood-, and imaging-related biomarkers

Neoadjuvant therapy (NAT) has been used increasingly in patients with locally advanced or early-stage breast cancer. However, the accurate evaluation and prediction of response to NAT remain the great challenge. Biomarkers could prove useful to identify responders or nonresponders, or even to distinguish between early and delayed responses. These biomarkers could include markers from the tumor itself, such as versatile proteins, genes, and ribonucleic acids, various biological factors or peripheral blood cells, and clinical and pathological features. Possible predictive markers could also include multiple features from functional imaging, such as standard uptake values in positron emission tomography, apparent diffusion coefficient in magnetic resonance, or radiomics imaging biomarkers. In addition, cells that indirectly present the immune status of tumor cells and/or their host could also potentially be used as biomarkers, eg, tumor-infiltrating lymphocytes, tumor-associated macrophages, and myeloid-derived suppressor cells. Though numerous biomarkers have been widely investigated, only estrogen and/or progesterone receptors and human epidermal growth factor receptor have been proven to be reliable biomarkers to predict the response to NAT. They are the only biomarkers recommended in several international guidelines. The other aforementioned biomarkers warrant further validation studies. Some multigene profiling assays that are commercially available, eg, Oncotype DX and MammaPrint, should be used with caution when extrapolated to NAT settings. A panel of combined multilevel biomarkers might be able to predict the response to NAT more robustly than individual biomarkers. To establish such a panel and its prediction model, reliable methods and extensive clinical validation are warranted.

Inflammatory breast cancer biology: the tumour microenvironment is key

Inflammatory breast cancer (IBC) is a rare and aggressive disease that accounts for ~2-4% of all breast cancers. However, despite its low incidence rate, IBC is responsible for 7-10% of breast cancer-related mortality in Western countries. Thus, the discovery of robust biological targets and the development of more effective therapeutics in IBC are crucial. Despite major international efforts to understand IBC biology, genomic studies have not led to the discovery of distinct biological mechanisms in IBC that can be translated into novel therapeutic strategies. In this Review, we discuss these molecular profiling efforts and highlight other important aspects of IBC biology. We present the intrinsic characteristics of IBC, including stemness, metastatic potential and hormone receptor positivity; the extrinsic features of the IBC tumour microenvironment (TME), including various constituent cell types; and lastly, the communication between these intrinsic and extrinsic components. We summarize the latest perspectives on the key biological features of IBC, with particular emphasis on the TME as an important contributor to the aggressive nature of IBC. On the basis of the current understanding of IBC, we hope to develop the next generation of translational studies, which will lead to much-needed survival improvements in patients with this deadly disease.

CD4+ Th1 to the rescue in HER-2+ breast cancer

HER2 overexpression leads to downregulation of MHC class-I. CD4⁺ Th1 cytokines, IFNγ and TNFα, and monoclonal antibodies, trastuzumab and pertuzumab, restore MHC class-I expression, and enable CD8⁺ recognition and cytolysis. Restoration of the anti-HER2 CD4⁺ Th1 immune response in combination with HER2 targeted therapy appear to be critical to successful anti-HER2 CD8⁺ immunotherapy.

Oncodriver inhibition and CD4+ Th1 cytokines cooperate through Stat1 activation to induce tumor senescence and apoptosis in HER2+ and triple negative breast cancer: implications for combining immune and targeted therapies

In patients with HER2-expressing breast cancer many develop resistance to HER2 targeted therapies. We show that high and intermediate HER2-expressing cancer cell lines are driven toward apoptosis and tumor senescence when treated with either CD4⁺ Th1 cells, or Th1 cytokines TNF-α and IFN-γ, in a dose dependent manner. Depletion of HER2 activity by either siRNA or trastuzumab and pertuzumab, and subsequent treatment with either anti-HER2 Th1 cells or TNF-α and IFN-γ resulted in synergistic increased tumor senescence and apoptosis in cells both sensitive and cells resistant to trastuzumab which was inhibited by neutralizing anti-TNF-α and IFN-γ. Th1 cytokines induced minimal senescence or apoptosis in triple negative breast cancer cells (TNBC); however, inhibition of EGFR in combination with Th1 cytokines sensitized those cells causing both senescence and apoptosis. TNF-α and IFN-γ led to increased Stat1 phosphorylation through serine and tyrosine sites and a compensatory reduction in Stat3 activation. Single agent IFN-γ enhanced Stat1 phosphorylation on tyrosine 701 and similar effects were observed in combination with TNF-α and EGFR inhibition. These results demonstrate Th1 cytokines and anti-oncodriver blockade cooperate in causing tumor senescence and apoptosis in TNBC and HER2-expressing breast cancer, suggesting these combinations could be explored as non-cross-reactive therapy preventing recurrence in breast cancer.

Correlates of immune and clinical activity of novel cancer vaccines

Cancer vaccines are solely meant to amplify the pool of type 1 cytokine oriented CD4+ and CD8+ T cells that recognize tumor antigen and ultimately foster control and destruction of a growing tumor. They are not designed to deal with all aspects of immune ignorance, exclusion, suppression and escape that are generally in place in patients with cancer and may prevent the T cells to enter the tumor or to exert their effector function. This simple fact prompted for a reappraisal of the many recent trials in which therapeutic cancer vaccines have been examined as monotherapy. In this review, I focus on trials examining therapeutic cancer vaccines at different stages of existing disease. The analysis of vaccine-induced immune responses and clinical activity of therapeutic cancer vaccines revealed four levels of evidence for vaccine efficacy. The lowest levels, reflect the many trials in which the strength of the tumor-reactive T cell response of vaccinated patients is associated with better clinical outcome or change in tumor marker. The highest levels indicate occasional regressions of tumors and metastases after vaccination or reflect a stronger clinical impact of vaccine in a randomized trial. A whole series of trials in which vaccine-induced tumor immunity correlates with the clinical impact of cancer vaccines in premalignant diseases, settings of low tumor burden or tumor regressions in patients with cancer, form an attest to the fact that cancer vaccines work. While the current number of true clinical responders in each cancer trial is too low for firm conclusions on immune correlates of clinical reactivity in cancer, extrapolation of the results from vaccinated patients with pre-cancers suggest a requirement of broad type 1 T cell reactivity.

Function of microRNA‑141 in human breast cancer through cytotoxic CD4+ T cells regulated by MAP4K4 expression

The present study investigated the anti‑cancer effect of microRNA (miRNA)‑141 on apoptosis rate of breast cancer cells and the possible underlying mechanism. In patients with breast cancer, the expression of miRNA‑141 was downregulated. Overexpression of miRNA‑141 reduced breast cancer cell growth, inhibited the expression of cyclooxygenase‑2 (COX‑2), prostaglandin E2 (PGE2) and tumor necrosis factor (TNF)‑α, and increased the expression levels of interleukin (IL)‑10. However, downregulation of miRNA‑141 resulted in upregulation of COX‑2, PGE2 and TNF‑α expression levels, and an inhibition of IL‑10. Overexpression of miRNA‑141 suppressed mitogen‑activated protein kinase kinase kinase kinase 4 (MAP4K4) protein expression. Downregulation of miRNA‑141 markedly upregulated MAP4K4 protein expression in MCF‑7 cells. Promotion of MAP4K4 protein expression reduced the effects of miRNA‑141 on the toxicity of CD4+ T cells on breast cancer cells. The results of the present study indicated that miRNA‑141 may cause anti‑tumor effects in human breast cancer cells via cytotoxic CD4+ T cells.

Immunotherapy in breast cancer: An introduction

The field of breast cancer immunology has progressed tremendously over the last decade. Twenty years ago immunotherapy was not considered for the treatment of breast cancers because breast cancer was not considered immunogenic. Today we know that most patients with breast cancer have some evidence of an adaptive immune response against their tumors, detectable either in the peripheral blood or in the tumor. Moreover, immunity to breast cancer begins at the earliest stages of the disease, in some patients prior to diagnosis. Recent evidence suggests that lymphocytes infiltrating breast cancers and found in the tumor stroma are strong prognostic indicators of a beneficial disease outcome. These observations now pave the way for the integration of immunomodulation into standard of care therapy for the treatment of breast cancer.

Predicting the Efficacy of HER2-Targeted Therapies: A Look at the Host

HER2 is overexpressed in 20% of invasive breast cancers (BCs) and correlates with a more aggressive disease. Until the advent of targeted agents, HER2 was associated with worse outcomes. Rationally designed HER2-targeted agents have been developed and introduced into clinical practice for women with HER2-amplified BC, improving disease-free and overall survival for primary and metastatic tumors. Trastuzumab, a recombinant humanized anti-HER2 monoclonal antibody, combined with chemotherapy, remains the standard of care for patients with HER2-positive BCs. However, many patients do not respond to this agent, whereas newer drugs have proven to be efficacious in clinical trials. The identification of biomarkers that select sensitive tumors and patients who will benefit from these new agents would help the incorporation of these therapies, limiting the risk of side effects and overtreatment and improving the outcomes of all patients with early-stage HER2-positive BC. We review the mechanisms of action of HER2-targeting agents, focusing on the involvement of the immune system and related predictive biomarkers.

Interplay between Natural Killer Cells and Anti-HER2 Antibodies: Perspectives for Breast Cancer Immunotherapy

Overexpression of the human epidermal growth factor receptor 2 (HER2) defines a subgroup of breast tumors with aggressive behavior. The addition of HER2-targeted antibodies (i.e., trastuzumab, pertuzumab) to chemotherapy significantly improves relapse-free and overall survival in patients with early-stage and advanced disease. Nonetheless, considerable proportions of patients develop resistance to treatment, highlighting the need for additional and co-adjuvant therapeutic strategies. HER2-specific antibodies can trigger natural killer (NK) cell-mediated antibody-dependent cellular cytotoxicity and indirectly enhance the development of tumor-specific T cell immunity; both mechanisms contributing to their antitumor efficacy in preclinical models. Antibody-dependent NK cell activation results in the release of cytotoxic granules as well as the secretion of pro-inflammatory cytokines (i.e., IFNγ and TNFα) and chemokines. Hence, NK cell tumor suppressive functions include direct cytolytic killing of tumor cells as well as the regulation of subsequent antitumor adaptive immunity. Albeit tumors with gene expression signatures associated to the presence of cytotoxic lymphocyte infiltrates benefit from trastuzumab-based treatment, NK cell-related biomarkers of response/resistance to HER2-specific therapeutic antibodies in breast cancer patients remain elusive. Several variables, including (i) the configuration of the patient NK cell repertoire; (ii) tumor molecular features (i.e., estrogen receptor expression); (iii) concomitant therapeutic regimens (i.e., chemotherapeutic agents, tyrosine kinase inhibitors); and (iv) evasion mechanisms developed by progressive breast tumors, have been shown to quantitatively and qualitatively influence antibody-triggered NK cell responses. In this review, we discuss possible interventions for restoring/enhancing the therapeutic activity of HER2 therapeutic antibodies by harnessing NK cell antitumor potential through combinatorial approaches, including immune checkpoint blocking/stimulatory antibodies, cytokines and toll-like receptor agonists.

Expression of T-Lymphocyte Markers in Human Epidermal Growth Factor Receptor 2-Positive Breast Cancer

Purpose

The present study aimed to examine the clinical implications of CD4, CD8, and FOXP3 expression on the prognosis of human epidermal growth factor receptor 2 (HER2)-positive breast cancer using a web-based database, and to compare the immunohistochemical expression of T-lymphocyte markers using primary and metastatic HER2-positive tumor tissues before and after HER2-targeted therapy.

Methods

Using the cBioPortal for Cancer Genomics and Kaplan-Meier plotter, the mRNA expression, association between T-lymphocyte markers, and survival in HER2-positive cancers were investigated according to various cutoff levels. Immunohistochemistry analysis was performed using paired primary and metastatic tissues of 29 HER2-positive tumors treated with systemic chemotherapy and HER2-directed therapy.

Results

HER2 mRNA was mutually exclusive of T-lymphocyte markers, and a significant correlation between T-cell markers was observed in the cBioPortal for Cancer Genomics. According to analysis of the Kaplan-Meier plotter, the impact of T-lymphocyte marker expression on survival was statistically insignificant in clinical HER2-positive tumors, irrespective of the cutoff levels. However, in the intrinsic HER2-positive subtype, the individual analyses of T-cell markers except for FOXP3 and combined analysis showed significantly favorable survival irrespective of cutoff points. Although the small clinical sample size made it difficult to show the statistical relevance of immunohistochemistry findings, good responses to neoadjuvant treatments might be associated with positive expression of combined T-lymphocyte markers, and approximately half of the samples showed discordance of combined markers between baseline and resistant tumors.

Conclusion

T-lymphocyte markers could be favorable prognostic factors in HER2-positive breast cancers; however, a consensus on patient section criteria, detection methods, and cutoff value could not be reached. The resistance to HER2-directed therapy might involve different and personalized mechanisms, and further research is required to understand the association between immune function and HER2 expression and to overcome the resistance mechanisms to HER2-targeted therapies.

Anti-HER2 CD4+ T-Helper Type 1 Immune Response is Superior to Breast MRI for Assessing Response to Neoadjuvant Therapy in Patients with HER2-Positive Breast Cancer

BACKGROUND

In human epidermal growth factor 2-positive breast cancer (HER2⁺BC), neoadjuvant chemotherapy and anti-HER2-targeted therapy (nCT) achieves a complete pathologic response (pCR) in 40-67% of patients. Posttreatment magnetic resonance imaging (pMRI) is considered the gold standard, with high specificity but lower sensitivity for assessing response. The authors previously determined that anti-HER2Th1 immune response is associated with pathologic response after nCT in HER2⁺BC patients. This study contrasted pMRI with anti-HER2Th1 response for assessing pCR in HER2⁺BC.

METHODS

A retrospective review of HER2⁺BC patients at the authors' institution was performed. Original pMRI reports were collected, and images were reviewed by a breast radiologist blinded to pCR and immune response. The post-nCT imaging-based tumor response was assessed by Response Evaluation Criteria in Solid Tumors. The anti-HER2Th1 response was determined by ex vivo stimulation of peripheral blood mononuclear cells with six major histocompatibility complex (MHC) class 2-derived HER2 peptides via enzyme-linked immunospot (ELISPOT). Posttreatment MRI and anti-HER2Th1 responses were cross-tabulated with pCR. Standard diagnostic metrics were computed.

RESULTS

For 30 patients, pMRI and anti-HER2Th1 immune response were measured, with 13 patients (43.3%) achieving pCR. The mean anti-HER2Th1 response in pCR was 167 (range 53-418), and <pCR was 24 (range 0.4-53). The distributions were nearly non-overlapping. The anti-HER2Th1 response was superior to the original pMRI and had higher accuracy than the blinded pMRI review (area under the curve 0.97 vs 0.55; sensitivity 100 vs 46.2%; specificity 94.1 vs 64.7%; overall accuracy 96.7 vs 56.7%).

CONCLUSION

The presence of a high anti-HER2Th1 response is superior to pMRI for the assessment of pCR in HER2⁺BC. This assay has considerable promise, and validation in a large-scale study is warranted.

Clinical significance of tumor-infiltrating lymphocytes in breast cancer

Tumor infiltrating lymphocytes (TIL) play an essential role in mediating response to chemotherapy and improving clinical outcomes in all subtypes of breast cancer. Triple negative breast cancers (TN) are most likely to have tumors with >50 % lymphocytic infiltrate, termed lymphocyte predominant breast cancer, and derive the greatest survival benefit from each 10 % increase in TIL. The majority of HER2+ breast cancers have similar level of immune infiltrate as TN breast cancer yet the presence of TILs has not shown the same survival benefit. For HER2+ breast cancers, type 1 T-cells, either increased TBET+ tumor infiltration or increased type 1 HER2-specific CD4+ T-cells in the peripheral blood, are associated with better outcomes. Hormone receptor positive HER2 negative tumors tend to have the least immune infiltrate yet are the only breast cancer subtype to show worse prognosis with increased FOXP3 regulatory T-cell infiltrate. Notably, all breast cancer subtypes have tumors with low, intermediate, or high TIL infiltrate. Tumors with high TILs may also have increased PD-L1 expression which might be the reason that TN breast cancer seems to demonstrate the most robust clinical response to immune checkpoint inhibitor therapy but further investigation is needed. Tumors with intermediate or low levels of pre-treatment immune infiltrate, on the other hand, may benefit from an intervention that may increase TIL, particularly type 1 T-cells. Examples of these interventions include specific types of cytotoxic chemotherapy, radiation, or vaccine therapy. Therefore, the systematic evaluation of TIL and specific populations of TIL may be able to both guide prognosis and the appropriate sequencing of therapies in breast cancer.

Malignant inflammation in cutaneous T-cell lymphoma-a hostile takeover

Cutaneous T-cell lymphomas (CTCL) are characterized by the presence of chronically inflamed skin lesions containing malignant T cells. Early disease presents as limited skin patches or plaques and exhibits an indolent behavior. For many patients, the disease never progresses beyond this stage, but in approximately one third of patients, the disease becomes progressive, and the skin lesions start to expand and evolve. Eventually, overt tumors develop and the malignant T cells may disseminate to the blood, lymph nodes, bone marrow, and visceral organs, often with a fatal outcome. The transition from early indolent to progressive and advanced disease is accompanied by a significant shift in the nature of the tumor-associated inflammation. This shift does not appear to be an epiphenomenon but rather a critical step in disease progression. Emerging evidence supports that the malignant T cells take control of the inflammatory environment, suppressing cellular immunity and anti-tumor responses while promoting a chronic inflammatory milieu that fuels their own expansion. Here, we review the inflammatory changes associated with disease progression in CTCL and point to their wider relevance in other cancer contexts. We further define the term "malignant inflammation" as a pro-tumorigenic inflammatory environment orchestrated by the tumor cells and discuss some of the mechanisms driving the development of malignant inflammation in CTCL.

Restoring Lost Anti-HER-2 Th1 Immunity in Breast Cancer: A Crucial Role for Th1 Cytokines in Therapy and Prevention

The ErbB/B2 (HER-2/neu) oncogene family plays a critical role in the development and metastatic spread of several tumor types including breast, ovarian and gastric cancer. In breast cancer, HER-2/neu is expressed in early disease development in a large percentage of DCIS lesions and its expression is associated with an increased risk of invasion and recurrence. Targeting HER-2 with antibodies such as trastuzumab or pertuzumab has improved survival, but patients with more extensive disease may develop resistance to therapy. Interestingly, response to HER-2 targeted therapies correlates with presence of immune response genes in the breast. Th1 cell production of the cytokines interferon gamma (IFNγ) and TNFα can enhance MHC class I expression, PD-L1 expression, augment apoptosis and tumor senescence, and enhances growth inhibition of many anti-breast cancer agents, including anti-estrogens and HER-2 targeted therapies. Recently, we have identified that a loss of anti-HER-2 CD4 Th1 in peripheral blood occurs during breast tumorigenesis and is dramatically diminished, even in Stage I breast cancers. The loss of anti-HER-2 Th1 response is specific and not readily reversed by standard therapies. In fact, this loss of anti-HER-2 Th1 response in peripheral blood correlates with lack of complete response to neoadjuvant therapy and diminished disease-free survival. This defect can be restored with HER-2 vaccinations in both DCIS and IBC. Correcting the anti-HER-2 Th1 response may have significant impact in improving response to HER-2 targeted therapies. Development of immune monitoring systems for anti-HER-2 Th1 to identify patients at risk for recurrence could be critical to improving outcomes, since the anti-HER-2 Th1 response can be restored by vaccination. Correction of the cellular immune response against HER-2 may prevent recurrence in high-risk patients with DCIS and IBC at risk of developing new or recurrent breast cancer.

Restoring anti-oncodriver Th1 responses with dendritic cell vaccines in HER2/neu-positive breast cancer: progress and potential

HER2/neu is expressed in the majority of in situ breast cancers, but maintained in 20-30% of invasive breast cancer (IBC). During breast tumorigenesis, there is a progressive loss of anti-HER2 CD4(pos) Th1 (anti-HER2Th1) from benign to ductal carcinoma in situ, with almost complete loss in IBC. This anti-HER2Th1 response can predict response to neoadjuvant therapy, risk of recurrence and disease-free survival. Vaccines consisting of HER2-pulsed type I polarized dendritic cells (DC1) administered during ductal carcinoma in situ and early IBC can efficiently correct anti-HER2Th1 response and have clinical impact on the disease. In this review, we will discuss the role of anti-HER2Th1 response in the three phases of immunoediting during HER2 breast cancer development and opportunities for reversing these processes using DC1 vaccines alone or in combination with standard therapies. Correcting the anti-HER2Th1 response may represent an opportunity for improving outcomes and providing a path to eliminate escape variants.

Loss of Anti-HER-3 CD4+ T-Helper Type 1 Immunity Occurs in Breast Tumorigenesis and is Negatively Associated with Outcomes

BACKGROUND

We previously demonstrated a progressive loss of the anti-human epidermal growth factor receptor 2 (HER2) CD4+ T-helper type 1 (Th1) response during HER2^pos breast tumorigenesis. This loss is associated with residual disease following neoadjuvant therapy and increased risk of recurrence. In this study, we assessed the fate of anti-HER3 Th1 immunity during breast tumorigenesis.

METHODS

Peripheral blood from 131 subjects, including healthy donors (HDs), patients with benign breast disease (BD), ductal carcinoma in situ (DCIS) and invasive breast cancer (IBC), was collected. Interferon (IFN)-γ^pos immune responses to four HER3-derived major histocompatibility complex (MHC) class II promiscuous peptides were tested via enzyme-linked immunosorbent (ELISPOT) assays, and three immune response parameters were compared: anti-HER3 (i) responsivity, or proportion of subjects responding to at least one peptide; (ii) repertoire, or number of responding peptides; and (iii) cumulative response, or summed peptide response.

RESULTS

A significant decline in anti-HER3 Th1 response was observed going from HDs to IBC patients; patients with triple-negative breast cancer (TNBC) demonstrated the lowest responses. HDs had significantly higher Th1 responses versus estrogen receptor (ER)^pos IBC and TNBC patients across all three immune parameters; HER2^pos IBC patients displayed responses similar to HDs and BDs. Patients with recurrent breast cancer and residual disease following neoadjuvant therapy demonstrated significantly lower anti-HER3 Th1 immunity compared with patients without recurrence or with a pathologic complete response to neoadjuvant therapy.

CONCLUSIONS

Anti-HER3 CD4+ Th1 responses decline during breast tumorigenesis, particularly in TNBC. Attempts to immunologically restore depressed responses in vulnerable subgroups may help mitigate recurrence.

Addition of anti-estrogen therapy to anti-HER2 dendritic cell vaccination improves regional nodal immune response and pathologic complete response rate in patients with ERpos/HER2pos early breast cancer

HER2-directed therapies are less effective in patients with ERpos compared to ERneg breast cancer, possibly reflecting bidirectional activation between HER2 and estrogen signaling pathways. We investigated dual blockade using anti-HER2 vaccination and anti-estrogen therapy in HER2pos/ERpos early breast cancer patients. In pre-clinical studies of HER2pos breast cancer cell lines, ERpos cells were partially resistant to CD4+ Th1 cytokine-induced metabolic suppression compared with ERneg cells. The addition of anti-estrogen treatment significantly enhanced cytokine sensitivity in ERpos, but not ERneg, cell lines. In two pooled phase-I clinical trials, patients with HER2pos early breast cancer were treated with neoadjuvant anti-HER2 dendritic cell vaccination; HER2pos/ERpos patients were treated with or without concurrent anti-estrogen therapy. The anti-HER2 Th1 immune response measured in the peripheral blood significantly increased following vaccination, but was similar across the three treatment groups (ERneg vaccination alone, ERpos vaccination alone, ERpos vaccination + anti-estrogen therapy). In the sentinel lymph nodes, however, the anti-HER2 Th1 immune response was significantly higher in ERpos patients treated with combination anti-HER2 vaccination plus anti-estrogen therapy compared to those treated with anti-HER2 vaccination alone. Similar rates of pathologic complete response (pCR) were observed in vaccinated ERneg patients and vaccinated ERpos patients treated with concurrent anti-estrogen therapy (31.4% vs. 28.6%); both were significantly higher than the pCR rate in vaccinated ERpos patients who did not receive anti-estrogen therapy (4.0%, p = 0.03). Since pCR portends long-term favorable outcomes, these results support additional clinical investigations using HER2-directed vaccines in combination with anti-estrogen treatments for ERpos/HER2pos DCIS and invasive breast cancer.