Targeted therapy in uterine serous carcinoma: an aggressive variant of endometrial cancer

Preclinical Activity of Datopotamab Deruxtecan, an Antibody-Drug Conjugate Targeting Trophoblast Cell-Surface Antigen 2, in Uterine Serous Carcinoma

Uterine serous carcinoma (USC) is a rare subset of endometrial cancer with a poor prognosis and high recurrence rate. Datopotamab deruxtecan (Dato-DXd) is a novel antibody-drug conjugate (ADC). The objective of this study was to evaluate the preclinical activity of Dato-DXd in USC in vitro against primary USC cell lines with various trophoblast cell-surface antigen 2 (TROP2) expression and in vivo in TROP2-overexpressing cell line-derived mice xenografts. USC primary tumor cell lines were treated with Dato-DXd and a control ADC (CTL ADC) to evaluate cell viability following exposure. Antibody-dependent cell-mediated cytotoxicity against TROP2-overexpressing and -nonexpressing cell lines was evaluated using a 4-hour chromium release assay. USC xenografts in mice were treated with Dato-DXd, CTL ADC, datopotamab, and vehicle to assess the in vivo effects via retro-orbital Dato-DXd administration. We found USC cell lines with TROP2 overexpression to be significantly more sensitive to killing induced by Dato-DXd compared with CTL ADC in vitro (e.g., IC50: 0.11 µmol/L vs. 30.07 µmol/L, P = 0.0074 and 0.11 µmol/L vs. 48.95 µmol/L, P = 0.0127, respectively). Dato-DXd induced antibody-dependent cell-mediated cytotoxicity in the presence of peripheral blood lymphocytes from healthy donors. TROP2-nonexpressing cell lines demonstrated minimal killing by Dato-DXd; however, when admixed with TROP2-overexpressing cells, a significant bystander effect was appreciated. In vivo, mice xenografts overexpressing TROP2 treated with Dato-DXd demonstrated tumor growth suppression and longer overall survival compared with CTL ADC-treated xenografts. These data demonstrate Dato-DXd to be highly active against TROP2-overexpressing USC in vitro and in vivo. Our preclinical activity results warrant future clinical trials for patients with advanced or recurrent USC.

SIGNIFICANCE

Targeted treatment of USC using the biomarker TROP2 represents a significant opportunity for further treatment options for patients already resistant to other lines of treatment. In this study, we present data showing preclinical evidence of effectiveness of this biomarker-targeted therapy in USC.

Evaluating the transcriptional fidelity of cancer models

BACKGROUND

Cancer researchers use cell lines, patient-derived xenografts, engineered mice, and tumoroids as models to investigate tumor biology and to identify therapies. The generalizability and power of a model derive from the fidelity with which it represents the tumor type under investigation; however, the extent to which this is true is often unclear. The preponderance of models and the ability to readily generate new ones has created a demand for tools that can measure the extent and ways in which cancer models resemble or diverge from native tumors.

METHODS

We developed a machine learning-based computational tool, CancerCellNet, that measures the similarity of cancer models to 22 naturally occurring tumor types and 36 subtypes, in a platform and species agnostic manner. We applied this tool to 657 cancer cell lines, 415 patient-derived xenografts, 26 distinct genetically engineered mouse models, and 131 tumoroids. We validated CancerCellNet by application to independent data, and we tested several predictions with immunofluorescence.

RESULTS

We have documented the cancer models with the greatest transcriptional fidelity to natural tumors, we have identified cancers underserved by adequate models, and we have found models with annotations that do not match their classification. By comparing models across modalities, we report that, on average, genetically engineered mice and tumoroids have higher transcriptional fidelity than patient-derived xenografts and cell lines in four out of five tumor types. However, several patient-derived xenografts and tumoroids have classification scores that are on par with native tumors, highlighting both their potential as faithful model classes and their heterogeneity.

CONCLUSIONS

CancerCellNet enables the rapid assessment of transcriptional fidelity of tumor models. We have made CancerCellNet available as a freely downloadable R package ( https://github.com/pcahan1/cancerCellNet ) and as a web application ( http://www.cahanlab.org/resources/cancerCellNet_web ) that can be applied to new cancer models that allows for direct comparison to the cancer models evaluated here.

A 4-gene signature predicts prognosis of uterine serous carcinoma

Background

Uterine serous carcinoma (USC) is an aggressive type of endometrial cancer that accounts for up to 40% of endometrial cancer deaths, creating an urgent need for prognostic biomarkers.

Methods

USC RNA-Seq data and corresponding patients’ clinical records were obtained from The Cancer Genome Atlas and Genotype-Tissue Expression datasets. Univariate cox, Lasso, and Multivariate cox regression analyses were conducted to forge a prognostic signature. Multivariable and univariable cox regression analysis and ROC curve evaluated the prediction efficiency both in the training and testing sets.

Results

We uncovered 1385 genes dysregulated in 110 cases of USC tissue relative to 113 cases of normal uterine tissue. Functional enrichment analysis of these genes revealed the involvement of various cancer-related pathways in USC. A novel 4-gene signature (KRT23, CXCL1, SOX9 and ABCA10) of USC prognosis was finally forged by serial regression analyses. Overall patient survival (OS) and recurrence-free survival (RFS) were significantly lower in the high-risk group relative to the low-risk group in both the training and testing sets. The area under the ROC curve of the 4-gene signature was highest among clinicopathological features in predicting OS and RFS. The 4-gene signature was found to be an independent prognostic indicator in USC and was a superior predictor of OS in early stage of USC.

Conclusions

Our findings highlight the potential of the 4-gene signature as a guide for personalized USC treatment.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-021-07834-4.

Kinome Profiling of Primary Endometrial Tumors Using Multiplexed Inhibitor Beads and Mass Spectrometry Identifies SRPK1 as Candidate Therapeutic Target

Endometrial carcinoma (EC) is the most common gynecologic malignancy in the United States, with limited effective targeted therapies. Endometrial tumors exhibit frequent alterations in protein kinases, yet only a small fraction of the kinome has been therapeutically explored. To identify kinase therapeutic avenues for EC, we profiled the kinome of endometrial tumors and normal endometrial tissues using Multiplexed Inhibitor Beads and Mass Spectrometry (MIB-MS). Our proteomics analysis identified a network of kinases overexpressed in tumors, including Serine/Arginine-Rich Splicing Factor Kinase 1 (SRPK1). Immunohistochemical (IHC) analysis of endometrial tumors confirmed MIB-MS findings and showed SRPK1 protein levels were highly expressed in endometrioid and uterine serous cancer (USC) histological subtypes. Moreover, querying large-scale genomics studies of EC tumors revealed high expression of SRPK1 correlated with poor survival. Loss-of-function studies targeting SRPK1 in an established USC cell line demonstrated SRPK1 was integral for RNA splicing, as well as cell cycle progression and survival under nutrient deficient conditions. Profiling of USC cells identified a compensatory response to SRPK1 inhibition that involved EGFR and the up-regulation of IGF1R and downstream AKT signaling. Co-targeting SRPK1 and EGFR or IGF1R synergistically enhanced growth inhibition in serous and endometrioid cell lines, representing a promising combination therapy for EC.

The Role of Eicosanoids in Gynecological Malignancies

Eicosanoids, bio-active lipid molecules, evoke a multitude of biological effects that directly affect cancer cells and indirectly affect tumor microenvironment. An emerging role has been shown for eicosanoids in the pathogenesis of gynecological malignancies which include cancers of the vulva, vagina, cervix, uterine, and ovary. Eicosanoid biosynthesis pathways start at the metabolism of phospholipids by phospholipase A2 then proceeding to one of three pathways: the cyclooxygenase (COX), lipoxygenase (LOX), or P450 epoxygenase pathways. The most studied eicosanoid pathways include COX and LOX; however, more evidence is appearing to support further study of the P450 epoxygenase pathway in gynecologic cancers. In this review, we present the current knowledge of the role of COX, LOX and P450 pathways in the pathogenesis of gynecologic malignancies. Vulvar and vaginal cancer, the rarest subtypes, there is association of COX-2 expression with poor disease specific survival in vulvar cancer and, in vaginal cancer, COX-2 expression has been found to play a role in mucosal inflammation leading to disease susceptibility and transmission. Cervical cancer is associated with COX-2 levels 7.4 times higher than in healthy tissues. Additionally, HPV elevates COX-2 levels through the EGFR pathway and HIV promotes elevated COX-2 levels in cervical tissue as well as increases PGE2 levels eliciting inflammation and progression of cancer. Evidence supports significant roles for both the LOX and COX pathways in uterine cancer. In endometrial cancer, there is increased expression of 5-LOX which is associated with adverse outcomes. Prostanoids in the COX pathway PGE2 and PGF2α have been shown to play a significant role in uterine cancer including alteration of proliferation, adhesion, migration, invasion, angiogenesis, and the inflammatory microenvironment. The most studied gynecological malignancy in regard to the potential role of eicosanoids in tumorigenesis is ovarian cancer in which all three pathways have shown to be associated or play a role in ovarian tumorigenesis directly on the tumor cell or through modulation of the tumor microenvironment. By identifying the gaps in knowledge, additional pathways and targets could be identified in order to obtain a better understanding of eicosanoid signaling in gynecological malignancies and identify potential new therapeutic approaches.

Prophylactic bilateral Salpingo-oophorectomy and eventual development of endometrial cancer: Two individual case reports

Prophylactic bilateral salpingo-oophorectomy (PBSO) is regularly performed when patients have a high risk of developing ovarian cancer (i.e. a personal or family history). Most commonly, PBSO is performed in pre-menopausal women who have completed childbearing. The major risk of uterine preservation is future development of endometrial cancer. We report two cases that highlight such occurrences in women who believed that the uterus was important for sexual function. The misunderstanding that the uterus is important for sexual satisfaction should be thoroughly discussed and rectified prior to initial surgery. This is especially important in patients who may eventually require hormone replacement therapy.

Pathogenesis and Clinical Management of Uterine Serous Carcinoma

Uterine serous carcinoma (USC) is an aggressive variant of endometrial cancer that has not been well characterized. It accounts for less than 10% of all endometrial cancers and 80% of endometrial cancer–related deaths. Currently, staging surgery together with chemotherapy or radiotherapy, especially vaginal cuff brachytherapy, is the main treatment strategy for USC. Whole-exome sequencing combined with preclinical and clinical studies are verifying a series of effective and clinically accessible inhibitors targeting frequently altered genes, such as HER2 and PI3K3CA, in varying USC patient populations. Some progress has also been made in the immunotherapy field. The PD-1/PD-L1 pathway has been found to be activated in many USC patients, and clinical trials of PD-1 inhibitors in USC are underway. This review updates the progress of research regarding the molecular pathogenesis and putative clinical management of USC.

Long noncoding RNA NEAT1 drives aggressive endometrial cancer progression via miR-361-regulated networks involving STAT3 and tumor microenvironment-related genes

BACKGROUND

High-grade endometrioid and serous endometrial cancers (ECs) are an aggressive subtype of ECs without effective therapies. The reciprocal communication between tumor cells and their surrounding microenvironment drives tumor progression. Long noncoding RNAs (lncRNAs) are key mediators of tumorigenesis and metastasis. However, little is known about the role of lncRNAs in aggressive EC progression and tumor microenvironment remodeling.

METHODS

We performed an array-based lncRNA analysis of a parental HEC-50 EC cell population and derivatives with highly invasive, sphere-forming, and paclitaxel (TX)-resistant characteristics. We characterized the roles of the lncRNA NEAT1 in mediating aggressive EC progression in vitro and in vivo and explored the molecular events downstream of NEAT1.

RESULTS

We identified 10 lncRNAs with upregulated expression (NEAT1, H19, PVT1, UCA1, MIR7-3HG, SNHG16, HULC, RMST, BCAR4 and LINC00152) and 10 lncRNAs with downregulated expression (MEG3, GAS5, DIO3OS, MIR155HG, LINC00261, FENDRR, MIAT, TMEM161B-AS1, HAND2-AS1 and NBR2) in the highly invasive, sphere-forming and TX-resistant derivatives. NEAT1 expression was markedly upregulated in early-stage EC tissue samples, and high NEAT1 expression predicted a poor prognosis. Inhibiting NEAT1 expression with small hairpin RNAs (shRNAs) diminished cellular proliferation, invasion, sphere formation, and xenograft tumor growth and improved TX response in aggressive EC cells. We showed that NEAT1 functions as an oncogenic sponge for the tumor suppressor microRNA-361 (miR-361), which suppresses proliferation, invasion, sphere formation and TX resistance by directly targeting the oncogene STAT3. Furthermore, miR-361 also suppressed the expression of multiple prometastatic genes and tumor microenvironment-related genes, including MEF2D, ROCK1, WNT7A, VEGF-A, PDE4B, and KPNA4.

CONCLUSIONS

NEAT1 initiates a miR-361-mediated network to drive aggressive EC progression. These data support a rationale for inhibiting NEAT1 signaling as a potential therapeutic strategy for overcoming aggressive EC progression and chemoresistance.

Effects of lymphadenectomy among women with stage IA endometrial cancer: a SEER database analysis

Aim: To determine whether lymphadenectomy is associated with increased survival of women with stage IA endometrial cancer. Methods: Patients diagnosed with endometrial cancer from 2004 to 2013 and whose clinicopathologic data were recorded in the SEER database were examined. Propensity matching paired subjects with similar background variables. Before and after matching, Kaplan–Meier curves were drawn for comparison. Results: In 11,603 patients, cardiovascular disease and diabetes were the most common causes of death. Before matching, lymphadenectomy significantly improved the overall survival of stage IA/grade 3–4 patients (p = 0.013), but after matching, lymphadenectomy did not prolong survival for any grade. Sentinel lymph nodes biopsy can reduce the number of resected lymph nodes (p = 8.387e-10 in Wilcox test) but can’t prolong survival. Conclusion: After matching, no significant difference in survival between lymphadenectomy and nonlymphadenectomy was observed for stage IA patients, sentinel lymph nodes group had fewer lymph node removed, but didn’t affect survival.

PP2A: A Promising Biomarker and Therapeutic Target in Endometrial Cancer

Over the last decade, the use of targeted therapies has immensely increased in the treatment of cancer. However, treatment for endometrial carcinomas (ECs) has lagged behind, although potential molecular markers have been identified. This is particularly problematic for the type II ECs, since these aggressive tumors are usually not responsive toward the current standard therapies. Therefore, type II ECs are responsible for most EC-related deaths, indicating the need for new treatment options. Interestingly, molecular analyses of type II ECs have uncovered frequent genetic alterations (up to 40%) in PPP2R1A, encoding the Aα subunit of the tumor suppressive heterotrimeric protein phosphatase type 2A (PP2A). PPP2R1A mutations were also reported in type I ECs and other common gynecologic cancers, albeit at much lower frequencies (0-7%). Nevertheless, PP2A inactivation in the latter cancer types is common via other mechanisms, in particular by increased expression of Cancerous Inhibitor of PP2A (CIP2A) and PP2A Methylesterase-1 (PME-1) proteins. In this review, we discuss the therapeutic potential of direct and indirect PP2A targeting compounds, possibly in combination with other anti-cancer drugs, in EC. Furthermore, we investigate the potential of the PP2A status as a predictive and/or prognostic marker for type I and II ECs.

Targeted Therapies in Type II Endometrial Cancers: Too Little, but Not Too Late

Type II endometrial carcinomas (ECs) are responsible for most endometrial cancer-related deaths due to their aggressive nature, late stage detection and high tolerance for standard therapies. However, there are no targeted therapies for type II ECs, and they are still treated the same way as the clinically indolent and easily treatable type I ECs. Therefore, type II ECs are in need of new treatment options. More recently, molecular analysis of endometrial cancer revealed phosphorylation-dependent oncogenic signalling in the phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K) and mitogen-activated protein kinase (MAPK) pathways to be most frequently altered in type II ECs. Consequently, clinical trials tested pharmacologic kinase inhibitors targeting these pathways, although mostly with rather disappointing results. In this review, we highlight the most common genetic alterations in type II ECs. Additionally, we reason why most clinical trials for ECs using targeted kinase inhibitors had unsatisfying results and what should be changed in future clinical trial setups. Furthermore, we argue that, besides kinases, phosphatases should no longer be ignored in clinical trials, particularly in type II ECs, where the tumour suppressive phosphatase protein phosphatase type 2A (PP2A) is frequently mutated. Lastly, we discuss the therapeutic potential of targeting PP2A for (re)activation, possibly in combination with pharmacologic kinase inhibitors.

ONC201 demonstrates anti-tumorigenic and anti-metastatic activity in uterine serous carcinoma in vitro

Uterine serous carcinoma (USC) represents an aggressive histologic subtype of endometrial cancer. It is associated with a poor prognosis, and improved therapies for women battling USCs are greatly needed. ONC201 is an orally bioavailable, first-in-class small molecule that induces tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) independent of p53. ONC201 has demonstrated anti-tumorigenic activity in pre-clinical models of solid tumors through induction of apoptosis and inactivation of the AKT/MAPK pathways. Recent phase I and II clinical trials have shown that ONC201 is well tolerated and may have single agent activity in high grade glioma patients among others. We sought to determine the effects of ONC201 on cell proliferation in USC and identify the mechanisms by which ONC201 inhibits cell growth in this disease. ONC201 inhibited cell proliferation in a dose-dependent manner in ARK1, ARK2 and SPEC-2 cell lines. The anti-proliferative activity of ONC201 in ARK1 and SPEC-2 cells was associated with induction apoptosis independent of p53 via both a TRAIL mediated apoptotic pathway and a mitochondrial apoptosis pathway. Treatment with ONC201 resulted in significant reduction in adhesion and invasion as well as inhibition of the AKT and MAPK pathways. In addition, ONC201 markedly potentiated the anti-tumorigenic effects of paclitaxel in USC cells. Our results suggest that ONC201 has significant anti-proliferative and anti-metastatic effects in USC cells through both induction of apoptosis and inhibition of the AKT and MAPK pathways. ONC201 and paclitaxel are a promising therapeutic combination in USC cells. Thus, ONC201 should be evaluated as a single agent and as a therapeutic partner with paclitaxel in future clinical trials of USC.

High expression of the p53 isoform γ is associated with reduced progression-free survival in uterine serous carcinoma

Background

Uterine serous carcinoma (USC) is a rare but aggressive subtype of endometrial carcinoma. Large-scale comprehensive efforts have resulted in an improved molecular understanding of its pathogenesis, and the p53 pathway has been proposed as a key player and is potentially targetable. Here we attempt to further portray the p53 pathway in USC by assessing p53 isoform expression.

Methods

We applied quantitative Real-Time PCRs (RT-qPCR) for expression analyses of total p53 mRNA as well as quantitative distinction of p53β, p53γ, and the total mRNA of amino-terminal truncated Δ40p53 and Δ133p53 in a retrospective cohort of 37 patients with USC. TP53 mutation status was assessed by targeted massive parallel sequencing. Findings were correlated with clinical data.

Results

The p53 isoform expression landscape in USCs was heterogeneous and dominated by total Δ133p53, while the distinct p53β and p53γ variants were found at much lower levels. The isoform expression profiles varied between samples, while their expression was independent of TP53 mutation status. We found high relative p53γ expression to be associated with reduced progression-free survival (PFS).

Conclusions

This is the first indication that elevated p53γ expression is associated with reduced PFS in USC. This single-center study may offer some insight in the landscape of p53 isoform expression in USC, but further validation studies are crucial to understand the context-dependent and tissue-specific role of the p53 isoform network in gynecological cancer.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-4591-3) contains supplementary material, which is available to authorized users.

Expression of Estrogen Receptors (ER), Progesterone Receptors (PR) and HER-2/neu receptors in Endometrial Carcinoma and their associations with histological types, grades and stages of the tumor

Objective:

To study and detect immunohistochemical expression of Estrogen Receptors, Progestrone Receptors and HER-2/neu Receptors in Endometrial Carcinoma (EC) and to find their associations with histological types, grades and stages of the tumor.

Methods:

A cross sectional study of one year duration from January 2016 to January 2017 was conducted at Histopathology department of Army Medical College, Rawalpindi. A non-probability purposive sampling technique was used to include 56 cases of EC. The specimens were tested for ER, PR and HER-2/neu expression using immunohistochemical analysis. Data was analyzed in SPSS and the significance of association of expression of the receptors with histological types, grades and stages of the tumor was assessed.

Results:

Significant association of Her-2/neu overexpression with histological types and grades of EC was seen, whereas the association of ER and PR expression with histological types, grades and stage of EC was statistically insignificant.

Conclusion:

It is suggested that EC showing over expression of HER2/neu with immunohistochemistry may be treated with anti HER-2/neu treatment with better chances of survival and decreased post-treatment morbidity.

New therapies for advanced, recurrent, and metastatic endometrial cancers

Endometrial cancer is the most common gynecologic malignancy in the United States, accounting for 6% of cancers in women. In 2017, an estimated 61,380 women were diagnosed with endometrial cancer, and approximately 11,000 died from this disease. From 1987 to 2008, there was a 50% increase in the incidence of endometrial cancer, with an approximate 300% increase in the number of associated deaths. Although there are many chemotherapeutic and targeted therapy agents approved for ovarian, fallopian tube and primary peritoneal cancers, since the 1971 approval of megestrol acetate for the palliative treatment of advanced endometrial cancer, only pembrolizumab has been Food and Drug Administration (FDA)-approved for high microsatellite instability (MSI-H) or mismatch repair deficient (dMMR) endometrial cancer; this highlights the need for new therapies to treat advanced, recurrent, metastatic endometrial cancer. In this review, we discuss current and emerging treatment options for endometrial cancer, including chemotherapy, targeted therapy, and immunotherapy. The National Cancer Institute (NCI) and others are now focusing their efforts on the design of scientifically rational targeted therapy and immunotherapy trials for specific molecular phenotypes of endometrial cancer. This is essential for the advancement of cancer care for women, which is threatened by a severe enrollment decline of approximately 80% for gynecologic oncology clinical trials.

Recent Advances in Endometrial Cancer

Endometrial cancer is the most common gynecologic malignancy in the United States, with yearly rates continuing to increase. Most women present with early stage disease; however, advanced disease carries a grave prognosis. As a result, novel therapies are currently under investigation for the treatment of endometrial cancer. These advances include a better understanding of the genetic basis surrounding the development of endometrial cancer, novel surgical therapies, and new molecular targets for the treatment of this disease. This review explores the literature regarding these advancements in endometrial cancer.

Improved i.p. drug delivery with bioadhesive nanoparticles

The i.p. administration of chemotherapy in ovarian and uterine serous carcinoma patients by biodegradable nanoparticles may represent a highly effective way to suppress peritoneal carcinomatosis. However, the efficacy of nanoparticles loaded with chemotherapeutic agents is currently hampered by their fast clearance by lymphatic drainage. Here, we show that a unique formulation of bioadhesive nanoparticles (BNPs) can interact with mesothelial cells in the abdominal cavity and significantly extend the retention of the nanoparticles in the peritoneal space. BNPs loaded with a potent chemotherapeutic agent [epothilone B (EB)] showed significantly lower systemic toxicity and higher therapeutic efficacy against i.p. chemotherapy-resistant uterine serous carcinoma-derived xenografts compared with free EB and non-BNPs loaded with EB.

Improved i.p. drug delivery with bioadhesive nanoparticles

The i.p. administration of chemotherapy in ovarian and uterine serous carcinoma patients by biodegradable nanoparticles may represent a highly effective way to suppress peritoneal carcinomatosis. However, the efficacy of nanoparticles loaded with chemotherapeutic agents is currently hampered by their fast clearance by lymphatic drainage. Here, we show that a unique formulation of bioadhesive nanoparticles (BNPs) can interact with mesothelial cells in the abdominal cavity and significantly extend the retention of the nanoparticles in the peritoneal space. BNPs loaded with a potent chemotherapeutic agent [epothilone B (EB)] showed significantly lower systemic toxicity and higher therapeutic efficacy against i.p. chemotherapy-resistant uterine serous carcinoma-derived xenografts compared with free EB and non-BNPs loaded with EB.

Afatinib demonstrates remarkable activity against HER2-amplified uterine serous endometrial cancer in vitro and in vivo

Background:

Uterine serous carcinomas (USCs) are an aggressive form of uterine cancer that may rely on HER2/neu amplification as a driver of proliferation. The objective of this paper is to assess the sensitivity of USC cell lines with and without HER2/neu gene amplification to afatinib, an irreversible ErbB tyrosine kinase inhibitor, and to test the efficacy of afatinib in the treatment of HER2-amplified USC xenografts.

Methods:

Eight of fifteen primary USC cell lines (four with HER2 amplification and four without) demonstrating similar in vitro growth rates were treated with scalar concentrations of afatinib. Effects on cell growth, signalling and cell cycle distribution were determined by flow cytometry assays. Mice harbouring xenografts of HER2/neu-amplified USC were treated with afatinib by gavage to determine the effect on tumour growth and overall survival.

Results:

Primary chemotherapy-resistant USC cell lines harbouring HER2/neu gene amplification were exquisitely sensitive to afatinib exposure (mean±s.e.m. IC₅₀=0.0056±0.0006 μM) and significantly more sensitive than HER2/neu-non-amplified USC cell lines (mean±s.e.m. IC₅₀=0.563±0.092 μM, P<0.0001). Afatinib exposure resulted in abrogation of cell survival, inhibition of HER2/neu autophosphorylation and S6 transcription factor phosphorylation in HER2/neu overexpressing USC and inhibited the growth of HER2-amplified tumour xenografts improving overall survival (P=0.0017).

Conclusions:

Afatinib may be highly effective against HER2/neu-amplified chemotherapy-resistant USC. The investigation of afatinib in patients harbouring HER2/neu-amplified USC is warranted.

Effect of mTOR inhibitors in nude mice with endometrial carcinoma and variable PTEN expression status

Background

The aim of this study was to investigate the sensitivity to rapamycin of endometrial cancer cells with different phosphatase and tensin homologue (PTEN) expression to understand the mechanism of resistance to mammalian target of rapamycin (mTOR) inhibitors in the treatment of endometrial cancer.

Material/Methods

Twenty specific pathogen-free female BALB/c mice received transplants of either HEC-1A (PTEN-positive) or Ishikawa (PTEN-negative) cells. Mice in the treatment group were injected intraperitoneally once a week for 4 consecutive weeks. The control group was injected weekly with phosphate buffer saline (PBS) for 4 consecutive weeks. Tumor volume, tumor mass, growth curves, and inhibition rate were measured, after which the mice were killed.

Results

Both tumor growth rate and size were slower in the treatment group than in the control group for all mice that received transplants of either HEC-1A or Ishikawa cells. The tumor inhibition rates in the treatment group were 48.1% and 67.1% in mice transplanted with HEC-1A and Ishikawa cells, respectively.

Conclusions

The inhibitory effects of rapamycin were enhanced in PTEN-negative Ishikawa tumor cells compared with PTEN-positive HEC-1A cells, which could explain the reduced effect of rapalogues in some endometrial cancer patients and help to understand the mechanism of resistance to this drug.