Identification of Immunogenic MHC Class II Human HER3 Peptides that Mediate Anti-HER3 CD4+ Th1 Responses and Potential Use as a Cancer Vaccine

The HER3/ERBB3 receptor is an oncogenic receptor tyrosine kinase that forms heterodimers with EGFR family members and is overexpressed in numerous cancers. HER3 overexpression associates with reduced survival and acquired resistance to targeted therapies, making it a potential therapeutic target in multiple cancer types. Here, we report on immunogenic, promiscuous MHC class II-binding HER3 peptides, which can generate HER3-specific CD4⁺ Th1 antitumor immune responses. Using an overlapping peptide screening methodology, we identified nine MHC class II-binding HER3 epitopes that elicited specific Th1 immune response in both healthy donors and breast cancer patients. Most of these peptides were not identified by current binding algorithms. Homology assessment of amino acid sequence BLAST showed >90% sequence similarity between human and murine HER3/ERBB3 peptide sequences. HER3 peptide-pulsed dendritic cell vaccination resulted in anti-HER3 CD4⁺ Th1 responses that prevented tumor development, significantly delayed tumor growth in prevention models, and caused regression in multiple therapeutic models of HER3-expressing murine tumors, including mammary carcinoma and melanoma. Tumors were robustly infiltrated with CD4⁺ T cells, suggesting their key role in tumor rejection. Our data demonstrate that class II HER3 promiscuous peptides are effective at inducing HER3-specific CD4⁺ Th1 responses and suggest their applicability in immunotherapies for human HER3-overexpressing tumors.

Cell-Free DNA and Circulating Tumor Cells: Comprehensive Liquid Biopsy Analysis in Advanced Breast Cancer

Purpose: Liquid biopsy provides a real-time assessment of metastatic breast cancer (MBC). We evaluated the utility of combining circulating tumor cells (CTC) and circulating tumor DNA (ctDNA) to predict prognosis in MBC.Experimental Design: We conducted a retrospective study of 91 patients with locally advanced breast cancer and MBC. CTCs were enumerated by CellSearch; the plasma-based assay was performed utilizing Guardant360 and the survival analysis using Kaplan-Meier curves.Results: Eighty-four patients had stage IV cancer, and 7 patients had no metastases. Eighty patients had CTC analysis: median number 2 (0-5,612). Blood samples [232 of 277 (84%)] had mutations. The average ctDNA fraction was 4.5% (0-88.2%) and number of alterations 3 (0-27); the most commonly mutated genes were TP53 (52%), PIK3CA (40%), and ERBB2 (20%). At the time of analysis, 36 patients (39.6%) were dead. The median follow-up for CTCs was 9 months; for ctDNA, it was 9.9 months. For CTCs and ctDNA, respectively, progression-free survival (PFS) was 4.2 and 5.2 months and overall survival (OS) was 18.7 and 21.5 months. There was a statistically significant difference in PFS and OS for baseline CTCs < 5 versus CTCs ≥ 5 (P = 0.021 and P = 0.0004, respectively); %ctDNA < 0.5 versus ≥ 0.5 (P = 0.003 and P = 0.012); number of alterations < 2 versus ≥ 2 (P = 0.059 borderline and P = 0.0015). A significant association by Fisher exact test was found between the number of alterations and the %ctDNA in the baseline sample (P < 0.0001).Conclusions: The study demonstrated that liquid biopsy is an effective prognostic tool. Clin Cancer Res; 24(3); 560-8. ©2017 AACR.

Cell-Free DNA and Circulating Tumor Cells: Comprehensive Liquid Biopsy Analysis in Advanced Breast Cancer

Purpose: Liquid biopsy provides a real-time assessment of metastatic breast cancer (MBC). We evaluated the utility of combining circulating tumor cells (CTC) and circulating tumor DNA (ctDNA) to predict prognosis in MBC.Experimental Design: We conducted a retrospective study of 91 patients with locally advanced breast cancer and MBC. CTCs were enumerated by CellSearch; the plasma-based assay was performed utilizing Guardant360 and the survival analysis using Kaplan-Meier curves.Results: Eighty-four patients had stage IV cancer, and 7 patients had no metastases. Eighty patients had CTC analysis: median number 2 (0-5,612). Blood samples [232 of 277 (84%)] had mutations. The average ctDNA fraction was 4.5% (0-88.2%) and number of alterations 3 (0-27); the most commonly mutated genes were TP53 (52%), PIK3CA (40%), and ERBB2 (20%). At the time of analysis, 36 patients (39.6%) were dead. The median follow-up for CTCs was 9 months; for ctDNA, it was 9.9 months. For CTCs and ctDNA, respectively, progression-free survival (PFS) was 4.2 and 5.2 months and overall survival (OS) was 18.7 and 21.5 months. There was a statistically significant difference in PFS and OS for baseline CTCs < 5 versus CTCs ≥ 5 (P = 0.021 and P = 0.0004, respectively); %ctDNA < 0.5 versus ≥ 0.5 (P = 0.003 and P = 0.012); number of alterations < 2 versus ≥ 2 (P = 0.059 borderline and P = 0.0015). A significant association by Fisher exact test was found between the number of alterations and the %ctDNA in the baseline sample (P < 0.0001).Conclusions: The study demonstrated that liquid biopsy is an effective prognostic tool. Clin Cancer Res; 24(3); 560-8. ©2017 AACR.

The clinical development of vaccines for HER2+ breast cancer: Current landscape and future perspectives

Human epidermal growth factor receptor 2 (HER2) is a tumor associated antigen over-expressed in 20-30% of cases of breast cancer. Passive immune therapy with HER2-directed monoclonal antibodies (mabs) has changed the natural history of this subset of breast tumors both in the localized and metastatic settings. The safety and efficacy of HER2 vaccines have been assessed in early phase clinical trials but to date clinically relevant results in late phase trials remain an elusive target. Here, we review the recent translational discoveries related to the interactions between the adaptive immune system and the HER2 antigen in breast cancer, results of published clinical trials, and future directions in the field of HER2 vaccine treatment development.

A comprehensive review of heregulins, HER3, and HER4 as potential therapeutic targets in cancer

Heregulins (HRGs) bind to the receptors HER3 or HER4, induce receptor dimerization, and trigger downstream signaling that leads to tumor progression and resistance to targeted therapies. Increased expression of HRGs has been associated with worse clinical prognosis; therefore, attempts to block HRG-dependent tumor growth have been pursued. This manuscript summarizes the function and signaling of HRGs and review the preclinical evidence of its involvement in carcinogenesis, prognosis, and treatment resistance in several malignancies such as colorectal cancer, non-small cell lung cancer, ovarian cancer, and breast cancer. Agents in preclinical development and clinical trials of novel therapeutics targeting HRG-dependent signaling are also discussed, including anti-HER3 and -HER4 antibodies, anti-metalloproteinase agents, and HRG fusion proteins. Although several trials have indicated an acceptable safety profile, translating preclinical findings into clinical practice remains a challenge in this field, possibly due to the complexity of downstream signaling and patterns of HRG, HER3 and HER4 expression in different cancer subtypes. Improving patient selection through biomarkers and understanding the resistance mechanisms may translate into significant clinical benefits in the near future.

A pilot phase II trial of cabergoline in the treatment of metastatic breast cancer

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Background: The prolactin receptor can be overexpressed in breast cancer, and pre-clinical data indicate that it contributes to the pathobiology of breast cancer. Cabergoline is a potent dopamine receptor agonist of D2 receptors and has a direct inhibitory effect on pituitary prolactin secretion resulting in reduced serum prolactin levels. Methods: A pilot phase II study of cabergoline in patients with metastatic breast cancer was conducted with primary end point of best overall response rate (ORR) among patients with measurable disease. Eligible patients had metastatic breast cancer, any receptors status was allowed, and there was no limit of prior lines of therapy. Both measurable and unmeasurable diseases (RECIST 1.1) were allowed. Cabergoline 1mg orally, twice weekly (1 cycle = 4 weeks) was given until disease progression or unacceptable toxicity. Immunohistochemistry prolactin receptor staining was performed on available baseline tumor tissue, and serum prolactin levels were serially assessed. Results: A total of 20 women were enrolled, 19 of whom were evaluable for response (one patient died on C1D7 of unrelated causes). Mean age was 62 (range 42-83); 15 (75%) were Caucasian; mean number of prior lines of therapy 5 (range 0-14). Tumor receptor statuses were distributed as follows: HR+/HER2+ 1(5%), HR+/HER2- 18 (80%), HR-/HER2+ 1 (5%). Analysis was performed after a median follow-up of 6.8 months (0.2-26.2). Best ORR was 8.3% among 12 patients with measurable disease. Results for secondary endpoints were as follows: 4-month CBR = 26% (including patients with measurable and non-measurable disease), median PFS = 1.9 months, and median OS = 10.4 months. Most common treatment related AEs were nausea (30%), fatigue (25%), and elevation in alkaline phosphatase (15%). The highest-grade AE was a single grade 3 treatment-related pain in extremity. Nine patients had sufficient baseline tissue for analysis, there was no correlation between baseline tumor prolactin receptor expression and clinical benefit ( p= 0.24). Additional correlative work is ongoing. Conclusions: Cabergoline was well tolerated and associated with modest anti-tumor activity. Clinical trial information: NCT01730729.

A phase II study of tivozanib in patients with metastatic and nonresectable soft-tissue sarcomas

Background

Soft tissue sarcomas (STSs) overexpress vascular endothelial growth factors (VEGF) and VEGF-receptors (VEGFR) activation have been associated with tumor aggressiveness. Tivozanib is a potent small molecule tyrosine kinase inhibitor against VEGFR1-3, with activity against PDGFRα/β and cKIT. The primary endpoint of this study was progression free survival (PFS) rate at 16 weeks. Secondary end points were overall survival (OS), response rate, safety and correlative studies.

Patients and methods

A Simon two-stage phase II trial was performed using tivozanib given orally at 1.5 mg daily, 3 week on 1 week off on a 28 day cycle until disease progression or intolerable toxicity.

Results

Fifty-eight patients were enrolled and treated with tivozanib. Leiomyosarcoma was the most common STS histological type in our cohort (47%) and 27 patients (46%) had received at least 3 lines of therapy prior to study entry. Up to 24 patients (41%) had prior VEGF targeted therapies. Partial response and stable disease were observed in 2 (3.6%) and 30 (54.5%) patients. The 16 week PFS rate was 36.4% [95% confidence interval (CI) 23.7-49.1] and a median PFS of 3.5 months (95% CI 1.8-3). Median OS observed was 12.2 months (95% CI 8.1-16.8). The most frequent all grade toxicities were fatigue (48.3%), hypertension (43.1%), nausea (31%) and diarrhea (27.6%). The most common grade three toxicity was hypertension (22.4%). Correlative studies demonstrate no correlation between the expression of VEGFR 1, 2 or 3, PDGFRα/β or FGF, and activity of tivozanib.

Conclusion

Tivozanib was well tolerated and showed antitumor activity with a promising median PFS and PFS rate at 4 months in a heavily pretreated population of metastatic STSs. Our results support further studies to assess the clinical efficacy of tivozanib in STS.

Clinical Trial Number

NCT01782313.

Preliminary results from a phase II study of nivolumab for patients with metastatic adrenocortical carcinoma (ACC)

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Background: ACC is an exceedingly rare malignancy with an estimated incidence of 0.7 cases per million per year. Patients presenting with metastatic disease have an estimated 5-year survival rate of < 15%, without effective standard treatment options. Immunotherapy approaches such as checkpoint inhibitors have emerged as effective therapies for multiple malignancies. Nivolumab, a monoclonal IgG4 antibody against the programmed death-1 (PD-1) receptor on T-cells, acts by inhibiting the interaction with PD-L1 and PD-L2 and thus eliciting an increased anti-tumor immune response. This phase II study will assess the efficacy of nivolumab monotherapy according to objective response rate (ORR) in patients with advanced ACC – the study is currently in the patient enrollment phase. Methods: Patients with metastatic or locally advanced ACC with disease progression after treatment with ≥ 1 line of therapy (including mitotane and/or chemotherapy), or not eligible for first-line chemotherapy are currently being enrolled on this phase II study. Nivolumab is given at a fixed dose of 240mg IV q2 weeks until confirmed disease progression, unacceptable toxicity, or withdrawal. Planned accrual of up to 33 patients will follow a Simon two stage design with interim analysis for efficacy after 10 evaluable patients are enrolled. Results: This is an initial report of the first 7 evaluable patients enrolled on study. Median age 57 years; female (4/7); endocrine hyperfunction (2/7); prior chemotherapy with EDP +/- mitotane (5/7). Patients were treated with a median of 4 doses of nivolumab. Median time to progression of 8 weeks. Best overall response rate thus far has been progression of disease in 5 pts, with 2 pts pending evaluation. Grade 3 or 4 adverse events (AEs) at least possibly related to nivolumab: tremor, hypokalemia (1 pt each). Reported grade 1 and 2 AEs: LFT elevation (3 pts), lower extremity edema (2 pts), lymphopenia, urinary frequency and fatigue (1 pt each). Conclusions: Nivolumab has been well tolerated in this population of patients with metastatic ACC. Clinical trial information: NCT02720484.

Targeted therapy: comprehensive review

The National Hospice and Palliative Care Organization estimates that in 2006, 44.1% of hospice admissions had cancer as primary diagnosis, still representing the most common diagnosis in this level of care. In the recent years, the treatment of cancer sustained unprecedented advances with better understanding of cancer biology. Growth factor receptors emerged as target for effective therapy providing significant clinical benefit, for example epidermal growth factor receptor 2 or human epidermal growth factor receptor 2 + breast cancer disease has been routinely treated with trastuzumab, a monoclonal antibody, with significant survival benefit. Other cancers had their treatment changed by targeted therapy. This article reviews concepts of cancer cell biology and analyze the current standard of care use of targeted therapy. The data highlights aspects of targeted therapy important to health care professionals involved in hospice and palliative care of patients with cancer.