Investigation of Tumor Heterogeneity Using Integrated Single-Cell RNA Sequence Analysis to Focus on Genes Related to Breast Cancer-, EMT-, CSC-, and Metastasis-Related Markers in Patients with HER2-Positive Breast Cancer

Human epidermal growth factor receptor 2 (HER2) protein, which is characterized by the amplification of ERBB2, is a molecular target for HER2-overexpressing breast cancer. Many targeted HER2 strategies have been well developed thus far. Furthermore, intratumoral heterogeneity in HER2 cases has been observed with immunohistochemical staining and has been considered one of the reasons for drug resistance. Therefore, we conducted an integrated analysis of the breast cancer single-cell gene expression data for HER2-positive breast cancer cases from both scRNA-seq data from public datasets and data from our cohort and compared them with those for luminal breast cancer datasets. In our results, heterogeneous distribution of the expression of breast cancer-related genes (ESR1, PGR, ERBB2, and MKI67) was observed. Various gene expression levels differed at the single-cell level between the ERBB2-high group and ERBB2-low group. Moreover, molecular functions and ERBB2 expression levels differed between estrogen receptor (ER)-positive and ER-negative HER2 cases. Additionally, the gene expression levels of typical breast cancer-, CSC-, EMT-, and metastasis-related markers were also different across each patient. These results suggest that diversity in gene expression could occur not only in the presence of ERBB2 expression and ER status but also in the molecular characteristics of each patient.

Lymphocyte-to-monocyte ratio as a prognostic and potential tumor microenvironment indicator in advanced soft tissue sarcoma treated with first-line doxorubicin therapy

Prognostic value of hematologic indices and their association with the tumor microenvironment (TME) remain unclear in advanced soft tissue sarcoma (STS). We aimed to evaluate their prognostic value and correlation with the TME status in advanced STS treated with first-line doxorubicin (DXR) therapy. Clinical data and three hematological indices, including lymphocyte-to-monocyte ratio (LMR), platelet-to-lymphocyte ratio, and neutrophil-to-lymphocyte ratio, were collected from 149 patients with advanced STS. The TME status was pathologically examined by CD3, CD68, and CD20 staining of resected tumor slides. In a multivariate Cox analysis, low LMR and absence of primary tumor resection were independently associated with worse overall survival (OS) (HR 3.93, p = 0.001; HR 1.71, p = 0.03). A prognostic model using these variables predicted OS with greater area under curves than those obtained using Systemic Inflammatory Score and Glasgow Prognostic Score. The LMR significantly correlated with the tumoral CD3/CD68-positive cell ratio in surgical specimens (R = 0.959, p = 0.04). In conclusion, LMR was a prognostic factor in advanced STS treated with first-line DXR therapy. LMR could partially reflect anti-tumor immunity in the TME and have the prognostic value. The potential role of LMR as an indicator of TME status warrants further investigation.

Low HER2 expression is a predictor of poor prognosis in stage I triple-negative breast cancer

Introduction

Triple-negative breast cancer (TNBC) is negative for hormone receptors and human epidermal growth factor receptor 2 (HER2). In stage I TNBC, adjuvant therapy or follow-up are performed according to risk factors, but clinical trial data is scarce. In recent years, it has been reported that HER2-low cases (1+/2+ and in situ hybridization negative) have different prognoses than HER2-0 cases. However, the risk of recurrence and risk factors in this HER2-low population for stage I TNBC have not yet been investigated.

Methods

Herein, out of 174 patients with TNBC who underwent surgery from June 2004 to December 2009 at the National Cancer Center Hospital (Tokyo), we retrospectively examined 42 cases diagnosed as T1N0M0 TNBC after excluding those treated with preoperative chemotherapy.

Results

All patients were female, the median age was 60.5 years, and 11 cases were HER2-low and 31 cases were HER2-0. The median follow-up period was 121 months. Postoperative adjuvant therapy was administered in 30 patients and recurrence occurred in 8 patients. HER2-low cases showed a significantly shorter disease-free survival (HR: 7.0; 95% CI: 1.2– 40.2; P=0.0016) and a trend towards shorter overall survival (hazard ratio [HR]: 4.2, 95% confidence interval [CI]: 0.58–31.4) compared with that of HER2-0 cases. HER2 was also identified as a factor for poor prognosis from the point- estimated values in univariate and multivariate analyses after confirming that there was no correlation between the other factors.

Conclusion

For patients with stage I TNBC, the HER2-low population had a significantly worse prognosis than the HER2-0 population.

Changes in HER3 expression profiles between primary and recurrent gynecological cancers

BACKGROUND

Human epidermal growth factor receptor-3 (HER3) is a member of the epidermal growth factor receptor family of receptor tyrosine kinases, and its overexpression is associated with inferior prognosis in several cancers. However, it is unclear whether HER3 expression status changes in tumor tissue at recurrence. Therefore, this study aimed to evaluate the changes in HER3 expression between primary and recurrent status in gynecological cancers.

METHODS

This retrospective study used matched-pair tissues of gynecological cancer patients at initial diagnosis and at recurrence. Immunohistochemical (IHC) scores of 3 + or 2 + were termed "HER3-high", while IHC scores of 1 + or 0 were designated as "HER3-low/zero".

RESULTS

A total of 86 patients (40 with ovarian cancers, 32 with endometrial cancers, and 14 with cervical cancers) were included in this study. In ovarian cancer, 67.5% and 80.0% of the patients received a HER3-high at initial and recurrent diagnosis, respectively. The H-score was significantly increased at recurrence (p = 0.004). The proportion of HER3-high endometrial cancer patients increased from 46.9% at initial diagnosis to 68.8% at recurrence, and the H-score tended to increase at recurrence (p = 0.08). The fraction of HER3-high-rated cervical cancer patients remained unchanged at 85.7% both at initial and recurrent diagnosis. The discordance rate of HER3 expression detection in initial and recurrent diagnosis samples was 27.5%, 53.1%, and 14.3% for ovarian, endometrial, and cervical cancers, respectively. Ovarian and endometrial cancers with a HER3-high recurrent score tended to show shorter median survival time than those with a HER3-low/zero recurrent rating.

CONCLUSION

Our findings suggest that, in main types of gynecological cancers, the proportion of patients having a HER3-high score increased from initial to recurrent diagnosis.

Single-Cell Transcriptome Profiling Reveals Intratumoral Heterogeneity and Molecular Features of Ductal Carcinoma In Situ

Ductal carcinoma in situ (DCIS) is a precursor to invasive breast cancer. The frequency of DCIS is increasing because of routine mammography; however, the biological features and intratumoral heterogeneity of DCIS remain obscure. To address this deficiency, we performed single-cell transcriptomic profiling of DCIS and invasive ductal carcinoma (IDC). DCIS was found to be composed of several transcriptionally distinct subpopulations of cancer cells with specific functions. Several transcripts, including long noncoding RNAs, were highly expressed in IDC compared to DCIS and might be related to the invasive phenotype. Closeness centrality analysis revealed extensive heterogeneity in DCIS, and the prediction model for cell-to-cell interactions implied that the interaction network among luminal cells and immune cells in DCIS was comparable to that in IDC. Additionally, transcriptomic profiling of HER2+ luminal DCIS indicated HER2 genomic amplification at the DCIS stage. These data provide novel insight into the intratumoral heterogeneity and molecular features of DCIS, which exhibit properties similar to IDC.

Abstract 5083: Changes in HER3 expression profiles between initial diagnosis and recurrence in gynecologic cancers

Background: HER3 (ErbB-3) is a member of the epidermal growth factor receptor family of receptor tyrosine kinases, and its overexpression is associated with poorer prognosis in several cancer types. It is unclear whether HER3 expression status changes in tumor tissue at relapse. The purpose of this study is to evaluate changes in HER3 expression between initial diagnosis and recurrence in gynecologic cancers.

Methods: This retrospective study included gynecologic cancer patients with matched paired tissues at the time of initial diagnosis and at the time of recurrence between 1999 and 2019 at National Cancer Center Hospital, Japan. Immunohistochemical (IHC) staining for HER3 was performed using formalin-fixed paraffin-embedded specimens. The primary antibody was HER3/ErbB3 (D22C5) XP Rabbit mAb (Cell Signaling Technology). HER3-positive was defined as an IHC score of 2+ or 3+, and HER3-negative was an IHC score of 0 or 1+, scored according to HER2 testing guidelines for gastroesophageal cancer. The H-score (range, 0-300) was calculated using the following formula: 3X+2Y+Z, where X, Y, and Z are the percentage of tumor cells showing strong, moderate, and weak staining intensity. The difference in HER3 expression between initial diagnosis and recurrence was evaluated using the χ2 test.

Results: Eighty-six patients with gynecologic cancers were included (40 ovarian; 32 endometrial; 14 cervical). In ovarian cancer, 67.5% and 80.0% of the patients were HER3-positive at initial diagnosis and recurrence, respectively. There was a statistically significant increase in H-Score at recurrence (p=0.004). The HER3-positive rate in patients with endometrial cancer increased from 46.9% at initial diagnosis to 68.8% at recurrence, and H-Score tended to increase at recurrence (p=0.08). Twelve of the 14 patients (85.7%) with cervical cancer were HER3-positive, both at initial diagnosis and at recurrence, and H-Score tended to increase at recurrence (p=0.19). The discordance rate of HER3 expression determination in samples at initial diagnosis and recurrence was 27.5%, 46.9%, and 14.3% for ovarian, endometrial, and cervical cancers, respectively.

Conclusion: Our findings suggest that HER3 expression may increase at recurrence in patients with gynecologic cancers. HER3-targeted therapy may represent a promising option to overcome treatment failure and improve patient outcomes.

Citation Format: Yuki Kojima, Kazuki Sudo, Hiroshi Yoshida, Shu Yazaki, Momoko Tokura, Shosuke Kita, Kasumi Yamamoto, Chiharu Mizoguchi, Hitomi S Okuma, Tadaaki Nishikawa, Emi Noguchi, Tatsunori Shimoi, Yasuhito Tanase, Masaya Uno, Mitsuya Ishikawa, Tomoyasu Kato, Kumiko Koyama, Maki Kobayashi, Tomoya Kakegawa, Yasuhiro Fujiwara, Kan Yonemori. Changes in HER3 expression profiles between initial diagnosis and recurrence in gynecologic cancers [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 5083.

Diagnostic value of tumor markers in identifying favorable or unfavorable subsets in patients with cancer of unknown primary: a retrospective study

Background

Routine measurement of tumor markers is not recommended in daily clinical practice for patients with cancer of unknown primary (CUP). We evaluated the diagnostic value of tumor markers in identifying favorable or unfavorable subsets in patients with CUP.

Methods

We retrospectively reviewed the medical records of patients who were diagnosed with CUP between October 2010 and July 2015 at the National Cancer Center Hospital. The tumor markers of the patients were examined, including squamous cell carcinoma antigen, cytokeratin fraction, carcinoembryonic antigen, sialyl Lewis X, neuron-specific enolase, pro-gastrin-releasing peptide, α-fetoprotein, protein induced by vitamin K absence or antagonist II, prostate-specific antigen, soluble interleukin-2 receptor, carbohydrate antigen 19–9, cancer antigen 125, cancer antigen 15–3, NCC-ST-439 (ST439), elastase-1, human chorionic gonadotropin, and sialyl-Tn (STN).

Results

Among 199 patients with suspected CUP, 90 were diagnosed with confirmed CUP (12 in the favorable subset and 78 in the unfavorable subset). No tumor markers showed 100% sensitivity for unfavorable subsets. ST439 (p = 0.03) and STN (p = 0.049) showed 100% specificity for unfavorable subsets.

Conclusions

For patients with suspected CUP who show elevated ST439 or STN levels, the treatment strategy should be based on the premise that the patient is likely to be placed in the unfavorable subset.

Locally advanced triple negative breast cancer arising from fibroadenoma with complete response to neoadjuvant chemotherapy: A case report

INTRODUCTION

Breast cancer arising from benign fibroadenoma (FA) is rare. The histological type of the former was either carcinoma in situ or early-stage invasive breast carcinoma with hormone receptor positive/HER2 (human epidermal growth factor receptor-2)-negative phenotype. Meanwhile, advanced breast cancer of triple negative (TN) phenotype such as our case is extremely uncommon and clinically challenging.

PRESENTATION OF CASE

We experienced a case of a 53-year-old woman that had invasive ductal carcinoma of TN phenotype in FA with multiple lymph node metastases. After receiving neoadjuvant chemotherapy (NAC), she underwent breast mastectomy and axillary dissection. The pathological examination on postoperative specimens revealed the dense fibrous stroma in the FA without any residual viable tumor cells and was considered as pathological complete response (pCR).

DISCUSSION

This is the first report presenting a case of NAC treatment for invasive ductal carcinoma (IDC) in FA. Furthermore, the patient achieved pCR even if IDC was located within FA. Diagnosing breast cancer in FA may be challenging as the carcinoma component may be hidden by the FA component. If imaging of FA became larger or abnormal changes during follow-up examinations, needle biopsy should be recommended for assessment of the lesion positively.

CONCLUSION

This is the first report presenting a case of advanced breast cancer in FA of TN phenotype with multiple lymph node metastases who achieved pCR even if IDC was located within FA.

Parathyroid carcinoma occurred in two glands in multiple endocrine neoplasia 1: a report on a rare case

Primary hyperparathyroidism is the most common hormonal manifestation associated with multiple endocrine neoplasia 1 (MEN1). It is generally caused by parathyroid hyperplasia, and parathyroid carcinoma is rare. Here, we report a case of MEN1 with parathyroid carcinoma in two parathyroid glands causing primary hyperparathyroidism. A 40-year-old man with primary hyperparathyroidism due to MEN1 underwent a total parathyroidectomy. His corrected calcium and intact PTH (i-PTH) serum levels were 10.8 mg/dL and 203 pg/mL, respectively. Although three glands were successfully removed, the left upper parathyroid gland could not be detected. Since the right lower parathyroid lesion had invaded into the thyroid, right lobectomy was performed. A portion of the left lower parathyroid tissue was transplanted into his forearm. The histological findings of the left lower and the right upper parathyroid glands were consistent with hyperplasia while that of the right lower parathyroid gland was parathyroid carcinoma. Since the post-surgical i-PTH levels remained high, the intrathyroidal lesion of the left lobe, which was initally diagnosed as an adenomatous nodule, was suspected to contain parathyroid tumor. A fine needle aspiration of the tumor revealed a high concentration of i-PTH. One week after the first surgery, a left thyroid lobectomy was performed. The pathological diagnosis of the tumor was parathyroid carcinoma. After the surgery, calcium and i-PTH levels were normal. Although it is rare, parathyroid carcinoma should be considered as a cause of hyperparathyroidism in MEN1 patients. Since it is difficult to diagnose parathyroid carcinoma before surgery, intraoperative findings are important for the appropriate treatment.

Molecular phylogeny of methanogens associated with flagellated protists in the gut and with the gut epithelium of termites

The molecular phylogeny of methanogenic archaea associated with the flagellated protist species Dinenympha and Microjoenia in the gut of termites, Reticulitermes speratus and Hodotermopsis sjoestedti, and those attached to the gut epithelium was examined based on PCR-amplified small-subunit ribosomal RNA genes. The sequences identified were classified into six groups within the genus Methanobrevibacter, including groups of yet uncharacterized novel species. Closely related methanogens were shared between Microjoenia and some Dinenympha cells in each termite. The methanogens harbored by the flagellates were phylogenetically different from the methanogens associated with the gut epithelium, suggesting that distinct methanogen species showed distinct spatial distributions in the termite gut.

Phylogenetic identification of hypermastigotes, Pseudotrichonympha, Spirotrichonympha, Holomastigotoides, and parabasalian symbionts in the hindgut of termites

The phylogenetic diversity of parabasalian flagellates was examined based on the sequences of small subunit ribosomal RNA genes amplified directly from the mixed population of flagellates in the hindgut of lower termites. In total, 33 representative sequences of parabasalids were recovered from eight termite species. Fluorescent-labeled oligonucleotide probes specific for certain sequences were designed and used for the in situ identification of parabasalian species by whole-cell hybridization. The hypermastigotes, Pseudotrichonympha grassii, Spirotrichonympha leidyi, and Holomastigotoides mirabile in the hindgut of Coptotermes formosanus, and Spirotrichonympha sp. and Trichonympha spp. in Hodotermopsis sjoestedti were identified. In the phylogenetic tree constructed, the sequences from the termites were dispersed within the groups of known members of parabasalids, reflecting the presence of diverse parabasalids in the hindgut of termites. There were three paraphyletic lineages of hypermastigotes represented by Pseudotrichonympha, Trichonympha, and Spirotrichonympha, in agreement with the morphology-based taxonomic groups. The analysis of the tree-root suggested that the Pseudotrichonympha group is the most probable ancient lineage of parabasalids and that the Trichonympha group is the secondly deep-branching lineage. The Spirotrichonympha group and the Trichomonadida may have emerged later.

Phylogenetic study of methanogens associated with rumen ciliates

The phylogeny of methanogenic archaea associated with ciliate protozoa in a sheep rumen was investigated. Ruminal ciliate protozoa were exhaustively washed and mixtures of genomic DNA extracted. Archaea-specific nested PCR amplification was conducted with the ciliate genomic mixture. The resultant small subunit (16S) ribosomal RNA gene (ssu rDNA) was cloned into Escherichia coli JM 109. Many methanogens were still observed on and/or in ciliate cells by fluorescent microscopy even after exhaustive washing with buffer. Partial sequences of ssu rDNA close to Methanobrevibacter smithii were dominant in the retrieved sequences. RFLP analyses on the retrieved sequences revealed the absence of Methanobrevibacter ruminantium in the protozoal preparation. The association of Methanobrevibacter spp. with ruminal ciliate protozoa was demonstrated by the isolation of archaeal ssu rDNA phylogenetically close to that of M. smithii.

Sulphate reduction and methanogenesis in the ovine rumen and porcine caecum: a comparison of two microbial ecosystems

A series of experiments was conducted to study the relationship between methanogenesis and sulphate reduction in ovine rumen and porcine caecum. Effect of 2-bromoethane sulphonate on hydrogen production by digesta suggested that the most important H2-disposal system in the rumen is methanogenesis and that methanogenesis is not predominant H2-disposal system in the porcine caecum. This inference was supported by the difference in predominant H2-utilizers in these two microbial ecosystems; Methanogenic bacteria (MB) were predominant in the rumen and sulphate reducing bacteria (SRB) were predominant in porcine caecum. Free sulphate levels in digesta appear to affect the relationship between MB and SRB. Sulphate levels in the rumen were likely to be insufficient for SRB to outcompete MB.