Progression-free and overall survival in patients with relapsed/refractory germ cell tumors treated with single-agent chemotherapy: endpoints for clinical trial design

Expression of CD44 is associated with aggressiveness in seminomas

BACKGROUND

Testicular germ cell tumors (TGCTs) exhibit diverse biological and pathological features and are divided in two main types, seminomas and nonseminomatous germ cell tumors (NSGCTs). CD44 is a cell surface receptor, which is highly expressed in malignancies and is implicated in tumorigenesis affecting cell-matrix interactions and cell signaling.

METHODS AND RESULTS

Here, we examined the expression of CD44 in tumor cell lines and in patients' material. We found that CD44 is over-expressed in TGCTs compared to normal tissues. Immunohistochemical staining in 71 tissue specimens demonstrated increased expression of CD44 in some patients, whereas CD44 was absent in normal tissue. In seminomas, a high percentage of tumor and stromal cells showed cytoplasmic and/or cell surface staining for CD44 as well as increased staining for CD44 in the tumor stroma was found in some cases. The increased expression of CD44 either in tumor cells or in stromal components was associated with tumor size, nodal metastasis, vascular/lymphatic invasion, and disease stage only in seminomas. The increased stromal expression of CD44 in TGCTs was positively associated with angiogenesis.

CONCLUSIONS

CD44 may exhibit diverse biological functions in seminomas and NSGCTs. The expression of CD44 in tumor cells as well as in tumor stroma fosters an aggressive phenotype in seminomas and should be considered in disease treatment.

Emergent Management of Growing Teratoma Syndrome: A Case Presentation

Growing teratoma syndrome (GTS) represents a rare yet significant complication following treatment for non-seminomatous germ cell tumors (NSGCT), characterized by the growth of mature teratoma elements despite prior chemotherapy. We present the case of a 30-year-old male who, following orchidectomy for NSGCT and subsequent chemotherapy, developed acute abdominal pain and pulmonary metastasis. Despite normal serum tumor markers, imaging revealed a large retroperitoneal mass encasing significant vessels. Surgical excision led to symptom resolution. This case underscores the diagnostic challenges GTS poses, the importance of imaging in diagnosis, and the efficacy of prompt surgical intervention in achieving favorable outcomes.

The Immune Landscape and Immunotherapeutic Strategies in Platinum-Refractory Testicular Germ Cell Tumors

Testicular germ cell tumors (TGCTs) are cancers with very good prognosis, even in the metastatic setting, with high curative potential mainly attributed to the introduction of cisplatin-based chemotherapy. However, approximately 15% of the patients develop platinum-refractory disease and suffer multiple relapses. Therefore, there is an unmet need for novel therapeutic agents with improved efficacy and minimal long-term side effects. Recent advances in the development of immunotherapeutic agents, particularly immune checkpoint inhibitors (ICIs), have offered an opportunity to test their activity in various tumor types, including GCTs. This review aims to analyze the immune microenvironment of these tumors and present the most recently available data from studies that have tested immunotherapeutic agents against GCTs. The majority of the available knowledge derives from case reports or small cohort studies, particularly those involving ICIs of the PD-1/PD-L1 axis alone or in combination with anti-CTLA-4 monoclonal antibodies. Other immunotherapeutic targeted approaches, including antibody-drug conjugates, antibody prodrugs, vaccines, tyrosine kinase inhibitors, chimeric antigen receptor (CAR) T-cell therapy, have biological rationales and have shown preliminary activity or are currently being tested. Growing evidence on these and other approaches will assist in broadening the currently limited treatment armamentarium against platinum-refractory TGCTs.

Predicting outcomes in female germ cell tumors using a modified International Germ Cell Cancer Collaborative Group classification system to guide management

OBJECTIVE

We previously developed preoperative and pre-chemotherapy modified versions of the male International Germ Cell Cancer Collaborative Group (IGCCCG) prognostic model and assessed it in female patients with germ cell tumors (GCTs). We sought to validate these modified IGCCCG (mIGCCCG) models in a new cohort.

METHODS

We queried institutional databases for female patients with GCTs treated at Memorial Sloan Kettering Cancer Center from 1/1/1990-6/1/2020. The mIGCCCG model classifies patients with non-dysgerminomas as good, intermediate, or poor risk based on tumor markers using male IGCCCG cutoffs and absence/presence of non-pulmonary/peritoneal visceral metastasis. In dysgerminomas, good- and intermediate-risk groups are defined by absence/presence of non-pulmonary/peritoneal visceral metastasis. Progression-free survival (PFS) and overall survival (OS) were estimated for each group in the validation and combined original and validation cohorts. Associations between individual clinical factors and outcomes were evaluated.

RESULTS

Among 183 female patients with GCTs, clinical characteristics and outcomes were similar between the original (n = 93) and validation (n = 90) cohorts. In multivariable models, higher stage, older age, and non-dysgerminoma histology predicted worse PFS and OS (p < 0.05). Among 162 patients who received chemotherapy, preoperative and pre-chemotherapy mIGCCCG models were significantly associated with PFS and OS (p < 0.001 for all groups). With the preoperative model, 3-year PFS rates were 94%, 76%, and 50% in the good-, intermediate-, and poor-risk patients, respectively; OS rates were 96%, 86%, and 52%, respectively. Even within stage groups, mIGCCCG risk classifications were associated with clinical outcomes.

CONCLUSIONS

A female-specific mIGCCCG risk model effectively stratifies patients and should be incorporated into clinical trials.

Phase II study of Disulfiram and Cisplatin in Refractory Germ Cell Tumors. The GCT-SK-006 phase II trial

BACKGROUND

Multiple relapsed/refractory germ cell tumor (GCT) patients have extremely poor prognosis. Cisplatin resistant testicular GCTs overexpress aldehyde-dehydrogenase (ALDH) isoforms and inhibition of ALDH activity by disulfiram is associated with reconstitution of cisplatin sensitivity in vitro as well as in animal model. This study aimed to determine the efficacy and toxicity of ALDH inhibitor disulfiram in combination with cisplatin in patients with multiple relapsed/refractory GCTs.

METHODS

Disulfiram was administered at a dose of 400 mg daily until progression or unacceptable toxicity, cisplatin was administered at dose 50 mg/m² day 1 and 2, every 3 weeks. Twelve evaluable patients had to be enrolled into the first cohort, and if 0 of 12 patients had treatment response, the study was to be terminated. The results of the first stage of the trial are presented in this report.

RESULTS

Twelve patients with multiple relapsed/refractory GCTs were enrolled in the phase II study from May 2019 to September 2021. Median number of treatment cycles was 2 (range 1-6). None of patients achieved objective response to treatment, therefore the study was terminated in first stage. Median progression-free survival was 1.4 months, 95% CI (0.7-1.5 months), and median overall survival was 2.9 months 95% CI (1.5-4.7 months). Disease stabilization for at least 3 months was observed in 2 (16.7%) patients. Treatment was well tolerated, however, 5 (41.7%) of patients experienced grade 3/4 fatigue, 4 (33.3%) thrombocytopenia, 3 (25.0%) anemia, while 2 (16.7%) experienced neutropenia, nausea and infection.

CONCLUSIONS

This study failed to achieve its primary endpoint and our data suggest limited efficacy of disulfiram in restoring sensitivity to cisplatin in multiple relapsed/refractory GCTs.

Phase II trial of nivolumab monotherapy and biomarker screening in patients with chemo‐refractory germ cell tumors

Objectives

Germ cell tumors are highly susceptible to chemotherapy; however, there is a lack of established treatments for consistently relapsing germ cell tumor. Therefore, in this phase II study, we evaluated the efficacy and safety of nivolumab for relapsed germ cell tumor.

Methods

Seventeen adult patients (median age 34 years) with refractory primary germ cell tumor after second‐line or higher chemotherapy were enrolled. Nivolumab was administered over 30 min at 240 mg/body every 2 weeks until disease progression or intolerable adverse event occurrence. The primary endpoint was the overall response rate.

Result

We performed a biomarker analysis of programmed death ligand‐1 expression and genomic sequencing. Tumor histology revealed nonseminoma and seminoma in 14 and three patients, respectively. Patients were pretreated with a median of three chemotherapy lines, and three patients received high‐dose chemotherapy. The median number of nivolumab doses was 3 (range 2–46). One patient showed a partial response and three showed stable disease. Responses were durable in one patient with a partial response and one patient with stable disease (median 90 and 68 weeks, respectively). Nivolumab was well‐tolerated, with only two Grade 3 adverse events observed. Programmed death ligand‐1 expression was not associated with objective responses. Genomic sequencing revealed a high tumor mutation burden in a patient with a durable partial response. While a small subset of chemorefractory germ cell tumors may respond to nivolumab, programmed death ligand‐1 is unreliable to measure response.

Conclusions

Tumor mutation burden is a potential biomarker for future testing of germ cell tumor response.

Overcoming Chemotherapy Resistance in Germ Cell Tumors

Testicular germ cell tumors (GCTs) are highly curable malignancies. Excellent survival rates in patients with metastatic disease can be attributed to the exceptional sensitivity of GCTs to cisplatin-based chemotherapy. This hypersensitivity is probably related to alterations in the DNA repair of cisplatin-induced DNA damage, and an excessive apoptotic response. However, chemotherapy fails due to the development of cisplatin resistance in a proportion of patients. The molecular basis of this resistance appears to be multifactorial. Tracking the mechanisms of cisplatin resistance in GCTs, multiple molecules have been identified as potential therapeutic targets. A variety of therapeutic agents have been evaluated in preclinical and clinical studies. These include different chemotherapeutics, targeted therapies, such as tyrosine kinase inhibitors, mTOR inhibitors, PARP inhibitors, CDK inhibitors, and anti-CD30 therapy, as well as immune-checkpoint inhibitors, epigenetic therapy, and others. These therapeutics have been used as single agents or in combination with cisplatin. Some of them have shown promising in vitro activity in overcoming cisplatin resistance, but have not been effective in clinical trials in refractory GCT patients. This review provides a summary of current knowledge about the molecular mechanisms of cisplatin sensitivity and resistance in GCTs and outlines possible therapeutic approaches that seek to overcome this chemoresistance.

Comprehensive Assessment of Selected Immune Cell Subpopulations Changes in Chemotherapy-Naïve Germ Cell Tumor Patients

The pattern of immune cell distribution in testicular germ cell tumors (GCT) significantly differs from the immune environment in normal testicular tissues. The present study aimed to evaluate the role of different leukocyte subpopulation in GCTs. A cohort of 84 chemotherapy-naïve GCT patients was analyzed. Immunophenotyping of peripheral blood leukocyte subpopulations was carried out by flow cytometry. In addition, the data assessing the immunophenotypes and the baseline clinicopathological characteristics of the included subjects were statistically evaluated. Their prognostic value for the assessment of progression-free survival (PFS) and overall survival (OS) was estimated. The percentage of different innate/adaptive immune cell subpopulations was significantly associated with poor risk-related clinical features, including the number of metastatic sites, presence of retroperitoneal, mediastinal, lung, brain and non-pulmonary visceral metastases as well as with the S-stage and International Germ Cell Consensus Classification Group (IGCCCG) risk groups. In univariate analysis, the percentages of neutrophils, eosinophils, dendritic cells type 2, lymphocytes and T cytotoxic cells were significantly associated with PFS, while the neutrophil, non-classical monocyte and lymphocyte percentage were associated with OS. However, all these outcome correlations were not independent of IGCCCG in multivariate analysis. The data indicated a link among different innate/adaptive peripheral immune cell subpopulations in GCT patients. In addition, the association between these subpopulations and tumor characteristics was also investigated. The findings of the present study may contribute to a deeper understanding of the interactions between cancer and innate/adaptive immune response in GCT patients.

Rapid Response to Pembrolizumab in a Chemo-Refractory Testicular Germ Cell Cancer with Microsatellite Instability-High

Testicular germ cell tumor (TGCT) is highly chemo-sensitive cancer; however, there is no established treatment for TGCT relapsed after multiple chemotherapy. Although pembrolizumab showed durable stable disease in some patients, no reliable biomarker for predicting response is available. High microsatellite instability (MSI) is rare in chemo-naïve TGCT. We report a TGCT patient with a rapid response to pembrolizumab. A 34-year-old Japanese male diagnosed with advanced TGCT underwent PCR-based testing of the primary site; it did not reveal MSI. He relapsed after four chemotherapy regimens: bleomycin, etoposide and cisplatin; paclitaxel, ifosfamide and cisplatin; vinblastine, ifosfamide and cisplatin; and irinotecan+nedaplatin with a total of 20 treatment cycles. Chemotherapy was thus discontinued. Re-examination by a CT-guided needle biopsy for progressing retroperitoneal lymph node (RPLN) metastases showed MSI-high; pembrolizumab was initiated. After only two doses, the human chorionic gonadotropin level decreased from 6500 to <1.0 IU/L. PET-CT showed shrinkage of the RPLN metastases with diminished metabolism. The patient is currently free from disease progression for 6 months from the start of pembrolizumab. This is the first report of refractory TGCT with MSI-high responding to pembrolizumab. We emphasize the utility of a metastatic-site biopsy to check the MSI status for refractory TGCT even when primary site is MSI-negative.

Reciprocal epigenetic remodeling controls testicular cancer hypersensitivity to hypomethylating agents and chemotherapy

Testicular germ cell tumors (TGCTs) are aggressive but sensitive to cisplatin-based chemotherapy. Alternative therapies are needed for tumors refractory to cisplatin with hypomethylating agents providing one possibility. The mechanisms of cisplatin hypersensitivity and resistance in TGCTs remain poorly understood. Recently, it has been shown that TGCTs, even those resistant to cisplatin, are hypersensitive to very low doses of hypomethylating agents including 5-aza deoxy-cytosine (5-aza) and guadecitabine. We undertook a pharmacogenomic approach in order to better understand mechanisms of TGCT hypomethylating agent hypersensitivity by generating a panel of acquired 5-aza-resistant TGCT cells and contrasting these to previously generated acquired isogenic cisplatin-resistant cells from the same parent. Interestingly, there was a reciprocal relationship between cisplatin and 5-aza sensitivity, with cisplatin resistance associated with increased sensitivity to 5-aza and 5-aza resistance associated with increased sensitivity to cisplatin. Unbiased transcriptome analysis revealed 5-aza-resistant cells strongly downregulated polycomb target gene expression, the exact opposite of the finding for cisplatin-resistant cells, which upregulated polycomb target genes. This was associated with a dramatic increase in H3K27me3 and decrease in DNMT3B levels in 5-aza-resistant cells, the exact opposite changes seen in cisplatin-resistant cells. Evidence is presented that reciprocal regulation of polycomb and DNMT3B may be initiated by changes in DNMT3B levels as DNMT3B knockdown alone in parental cells resulted in increased expression of H3K27me3, EZH2, and BMI1, conferred 5-aza resistance and cisplatin sensitization, and mediated genome-wide repression of polycomb target gene expression. Finally, genome-wide analysis revealed that 5-aza-resistant, cisplatin-resistant, and DNMT3B-knockdown cells alter the expression of a common set of polycomb target genes. This study highlights that reciprocal epigenetic changes mediated by DNMT3B and polycomb may be a key driver of the unique cisplatin and 5-aza hypersensitivity of TGCTs and suggests that distinct epigenetic vulnerabilities may exist for pharmacological targeting of TGCTs.

Mediastinal Germ Cell Tumors: A Review and Update on Pathologic, Clinical, and Molecular Features

Mediastinal germ cell tumors (MGCTs) are the most common extragonadal germ cell tumors (GCTs) and most often arise in the anterior mediastinum with a male predilection. MGCTs also have a predilection for patients with Klinefelter syndrome and possibly other genetic conditions. MGCTs, as GCTs at other extragonadal sites, are thought to arise from germ cells improperly retained during migration along the midline during embryogenesis. Similar to their counterparts in the testes, MGCTs are classified into seminomatous and nonseminomatous GCTs. Seminomatous MGCT represents pure seminoma, whereas nonseminomatous MGCTs encompass pure yolk sac tumors, embryonal carcinoma, choriocarcinoma, mature or immature teratoma, and mixed GCTs with any combination of GCT types, including seminoma. Somatic-type or hematologic malignancies can also occur in association with a primary MGCT. MGCTs share molecular findings with GCTs at other sites, most commonly the presence of chromosome 12p gains and isochromosome i(12p). Treatment includes neoadjuvant chemotherapy followed by surgical resection of residual tumor, with the exception of benign teratomas, which require only surgical resection without chemotherapy. In this review, we highlight and provide an update on pathologic, clinical, and molecular features of MGCTs. Immunohistochemical profiles of each tumor type, as well as differential diagnostic considerations, are discussed.

Gemcitabine, carboplatin and veliparib in multiple relapsed/refractory germ cell tumours: The GCT-SK-004 phase II trial

Background Patients with multiple relapsed/refractory germ cell tumours (GCTs) have an extremely poor prognosis. PARP (poly-ADP-ribose polymerase) is overexpressed in GCTs compared to normal testes, and PARP overexpression is an early event in GCT development. This study aimed to determine the efficacy and toxicity of gemcitabine, carboplatin and the PARP inhibitor veliparib in patients with multiple relapsed/refractory GCTs. Methods Fifteen patients with multiple relapsed/refractory GCTs were enrolled in this phase II study from October 2016 to October 2020. Gemcitabine was administered at a dose of 800 mg/m2 on days 1 and 8 every 3 weeks; carboplatin at a target AUC of 4 on day 1 every 3 weeks; and veliparib at a dose of 250 mg b.i.d. throughout. The primary end point was 12-month progression-free survival (PFS). Results The median number of treatment cycles was 4 (range 2-8). Twelve-month PFS was achieved in 1 (6.7 %) patient. The median PFS was 3.1 months (95 % CI 2.2-3.9), and the median overall survival was 10.5 months (95 % CI 8.9-11.1). Partial remission was achieved in 4 (26.7 %) patients, and disease stabilization was observed in 5 (33.3 %) patients. A favourable response was achieved in 3 (20.0 %) patients. Treatment was well tolerated; however, 11 (73.3 %) patients experienced grade 3/4 neutropenia, 10 (66.7 %) experienced thrombocytopenia, 5 (33.3 %) anaemia and 2 (13.3 %) febrile neutropenia. Conclusions This study failed to achieve its primary endpoint, and our data suggest limited efficacy of gemcitabine, carboplatin and veliparib for multiple relapsed/refractory GCTs. ClinicalTrials.gov Identifier: NCT02860819, registered August 9, 2016.

Between a Rock and a Hard Place: An Epigenetic-Centric View of Testicular Germ Cell Tumors

Simple Summary

This minireview focuses on the role of epigenetics in testicular cancer. A working model is developed that postulates that epigenetic features that drive testicular cancer malignancy also enable these tumors to be cured at a high rate with chemotherapy. Chemoresistance may occur by epigenetic uncoupling of malignancy and chemosensitivity, a scenario that may be amenable to epigenetic-based therapies.

Abstract

Compared to many common solid tumors, the main genetic drivers of most testicular germ cell tumors (TGCTs) are unknown. Decades of focus on genomic alterations in TGCTs including awareness of a near universal increase in copies of chromosome 12p have failed to uncover exceptional driver genes, especially in genes that can be targeted therapeutically. Thus far, TGCT patients have missed out on the benefits of targeted therapies available to treat most other malignancies. In the past decade there has been a greater appreciation that epigenetics may play an especially prominent role in TGCT etiology, progression, and hypersensitivity to conventional chemotherapy. While genetics undoubtedly plays a role in TGCT biology, this mini-review will focus on the epigenetic “states” or features of testicular cancer, with an emphasis on DNA methylation, histone modifications, and miRNAs associated with TGCT susceptibility, initiation, progression, and response to chemotherapy. In addition, we comment on the current status of epigenetic-based therapy and epigenetic biomarker development for TGCTs. Finally, we suggest a unifying “rock and a hard place” or “differentiate or die” model where the tumorigenicity and curability of TGCTs are both dependent on common but still ill-defined epigenetic states.

m6A RNA methylation regulators play an important role in the prognosis of patients with testicular germ cell tumor

Background

N6-methyladenosine (m6A) is found to be associated with promoting tumorigenesis in different types of cancers, however, the function of m6A-related genes in testicular germ cell tumors (TGCT) development remains to be illuminated. This study aimed to investigated the prognostic value of m6A RNA methylation regulators in TGCT.

Methods

We collected TGCT patients’ information about clinicopathologic parameters and twenty-two m6A regulatory genes expression from The Cancer Genome Atlas (TCGA) database and Genotype-Tissue Expression (GTEx). We analyzed the differentially expressed m6A RNA methylation regulators between tumor tissues and normal tissues, as well as the correlation of m6A RNA methylation regulators. By using Cox univariate analysis, last absolute shrinkage and selection operator (LASSO) Cox regression algorithm and Cox multivariate proportional hazards regression analysis, a risk score was constructed based on a TCGA training cohort, and further verified in the TCGA testing cohort. Then, univariate and multivariate Cox regression analyses were used to evaluate the relationship between risk score and progression-free survival (PFS) in TGCT. Finally, the six-gene risk score was further verified by two gene expression profiles (GSE3218 and GSE10783) as an independent external validation cohort.

Results

Distinct expression patterns of m6A regulatory genes were identified between TGCT tissues and normal tissues in TCGA and GTEx datasets. To predict prognosis of TGCT patients, a risk score was calculated based on six selected m6A RNA methylation regulators (YTHDF1, RBM15, IGF2BP1, ZC3H13, METTL3, and FMR1). Additionally, we found significant differences between the high-risk and low-risk groups in serum marker study levels and histologic subtype. Univariate and multivariate analysis indicated that high risk score was associated with unfavorable PFS. Ultimately, the risk score was further verified by two gene expression profiles (GSE3218 and GSE10783).

Conclusions

Based on six selected m6A RNA methylation regulators, we developed a m6A methylation related risk score that can independently predict the prognosis of TGCT patients, and verify the prediction efficiency in TCGA and GEO datasets. Patients in high-risk group were associated with serum tumor marker study levels beyond the normal limits, non-seminoma, and unfavorable survival time. However, further prospective experiments should be carried out to verify our results.

A phase 1 study of combined guadecitabine and cisplatin in platinum refractory germ cell cancer

Purpose

Germ cell tumors (GCTs) are cured with therapy based on cisplatin, although a clinically significant number of patients are refractory and die of progressive disease. Based on preclinical studies indicating that refractory testicular GCTs are hypersensitive to hypomethylating agents (HMAs), we conducted a phase I trial combining the next‐generation HMA guadecitabine (SGI‐110) with cisplatin in recurrent, cisplatin‐resistant GCT patients.

Methods

Patients with metastatic GCTs were treated for five consecutive days with guadecitabine followed by cisplatin on day 8, for a 28‐day cycle for up to six cycles. The primary endpoint was safety and toxicity including dose‐limiting toxicity (DLT) and maximum tolerated dose (MTD).

Results

The number of patients enrolled was 14. The majority of patients were heavily pretreated. MTD was determined to be 30 mg/m² guadecitabine followed by 100 mg/m² cisplatin. The major DLTs were neutropenia and thrombocytopenia. Three patients had partial responses by RECIST criteria, two of these patients, including one with primary mediastinal disease, completed the study and qualified as complete responses by serum tumor marker criteria with sustained remissions of 5 and 13 months and survival of 16 and 26 months, respectively. The overall response rate was 23%. Three patients also had stable disease indicating a clinical benefit rate of 46%.

Conclusions

The combination of guadecitabine and cisplatin was tolerable and demonstrated activity in patients with platinum refractory germ cell cancer.

Hypermethylation and global remodelling of DNA methylation is associated with acquired cisplatin resistance in testicular germ cell tumours

Testicular germ cell tumours (TGCTs) respond well to cisplatin-based therapy. However, cisplatin resistance and poor outcomes do occur. It has been suggested that a shift towards DNA hypermethylation mediates cisplatin resistance in TGCT cells, although there is little direct evidence to support this claim. Here we utilized a series of isogenic cisplatin-resistant cell models and observed a strong association between cisplatin resistance in TGCT cells and a net increase in global CpG and non-CpG DNA methylation spanning regulatory, intergenic, genic and repeat elements. Hypermethylated loci were significantly enriched for repressive DNA segments, CTCF and RAD21 sites and lamina associated domains, suggesting that global nuclear reorganization of chromatin structure occurred in resistant cells. Hypomethylated CpG loci were significantly enriched for EZH2 and SUZ12 binding and H3K27me3 sites. Integrative transcriptome and methylome analyses showed a strong negative correlation between gene promoter and CpG island methylation and gene expression in resistant cells and a weaker positive correlation between gene body methylation and gene expression. A bidirectional shift between gene promoter and gene body DNA methylation occurred within multiple genes that was associated with upregulation of polycomb targets and downregulation of tumour suppressor genes. These data support the hypothesis that global remodelling of DNA methylation is a key factor in mediating cisplatin hypersensitivity and chemoresistance of TGCTs and furthers the rationale for hypomethylation therapy for refractory TGCT patients.

Epigenetic alterations of testicular germ cell tumours

PURPOSE OF REVIEW

Testicular germ cell tumours (TGCTs) exhibit, in contrast to other cancer types, a relatively low mutational burden. However, numerous epigenetic alterations have been shown to impact TGCT. In this review, we summarize the most relevant findings of the past 2 years.

RECENT FINDINGS

Recent studies focused on the functions of microRNAs and the impact of aberrant DNA methylation. Moreover, several epigenetic drugs with antineoplastic effects in TGCTs were identified.

SUMMARY

Aberrant DNA methylation and differentially expressed microRNAs have an important effect on TGCT pathogenesis. Moreover, differential DNA methylation patterns were found to be specific for different TGCT subtypes. Various microRNAs, such as miR-371a-3p, were found to be highly sensitive and specific biomarkers for TGCT. The epigenetic drugs guadecitabine, animacroxam, and JQ1 showed promising effects on TGCT in preclinical in-vivo and in-vitro studies.

Immunotherapy in Testicular Germ Cell Tumors

Testicular germ cell tumors (TGCTs) are malignancies with very high curative potential even in metastatic settings, mainly due to the introduction of cisplatin in the treatment of this disease. However, in a group of patients with cisplatin-refractory disease or with progressive disease despite high-dose salvage chemotherapy treatment, the prognosis is typically dismal. The triple combination of gemcitabine, oxaliplatin, and paclitaxel (GOP) has reasonable efficacy and is considered to be standard care for this group of patients. It remains to be seen, however, whether refractory TGCTs may represent a potential target for immune checkpoint inhibition. This review will focus on the rationale of the use of immunotherapy for platinum-refractory TGCTs and summarize data reporting experiences with immune checkpoint inhibitor treatment for this malignancy.

Expression and roles of system L amino acid transporters in human embryonal carcinoma cells

BACKGROUND

Testicular germ cell tumors (TGCTs) are the most common malignant cancer in young men. Although TGCTs are generally responsive to platinum-based chemotherapy particularly cisplatin, acquired resistance in patients with metastasis still occurs resulting in poor prognosis. Specifically, differentiation of embryonal carcinoma (EC) cells, the stem cells of TGCTs, can lead to the reduction of cisplatin responsiveness. Therefore, novel therapeutic strategies for TGCTs are needed. System L amino acid transporters have been reported to be up-regulated and to play an important role in tumorigenesis. However, expression and role of system L amino acid transporters in TGCTs remain elusive.

MATERIALS AND METHODS

Expression of system L amino acid transporters was analyzed in TGCT samples from The Cancer Genome Atlas (TCGA). Expression of LAT1, LAT2, and 4F2hc was examined in human embryonal carcinoma cell line NTERA2. Roles of system L amino acid transporters on NTERA2 cell survival, cell proliferation, pluripotency, and cisplatin sensitivity were evaluated.

RESULTS

Based upon TCGA datasets, we found that two isoforms of system L (LAT1 and LAT2) and their chaperone protein 4F2hc are highly expressed in EC samples compared with other groups. Treatment with the system L inhibitor BCH significantly suppressed leucine uptake into the pluripotent EC cell line NTERA2. The malignant phenotypes including cell viability, cell proliferation, and clonal ability were decreased following BCH treatment. Nonetheless, system L inhibition did not alter expression of stemness genes in NTERA2 cells. After NTERA2 differentiation, expressions of LAT1 and LAT2 were decreased. Finally, co-administration of BCH enhanced cisplatin sensitivity in both undifferentiated and differentiated cells. These effects were associated with the reduction in p70S6K phosphorylation.

CONCLUSION

Taken together, these results shed light on the roles of system L amino acid transporters in TGCTs. Therefore, system L amino acid transporters could provide novel therapeutic targets for treatment against TGCTs.

Disulfiram Overcomes Cisplatin Resistance in Human Embryonal Carcinoma Cells

Cisplatin resistance in testicular germ cell tumors (TGCTs) is a clinical challenge. We investigated the underlying mechanisms associated with cancer stem cell (CSC) markers and modalities circumventing the chemoresistance. Chemoresistant models (designated as CisR) of human embryonal carcinoma cell lines NTERA-2 and NCCIT were derived and characterized using flow cytometry, gene expression, functional and protein arrays. Tumorigenicity was determined on immunodeficient mouse model. Disulfiram was used to examine chemosensitization of resistant cells. ALDH1A3 isoform expression was evaluated by immunohistochemistry in 216 patients' tissue samples. Chemoresistant cells were significantly more resistant to cisplatin, carboplatin and oxaliplatin compared to parental cells. NTERA-2 CisR cells exhibited altered morphology and increased tumorigenicity. High ALDH1A3 expression and increased ALDH activity were detected in both refractory cell lines. Disulfiram in combination with cisplatin showed synergy for NTERA-2 CisR and NCCIT CisR cells and inhibited growth of NTERA-2 CisR xenografts. Significantly higher ALDH1A3 expression was detected in TGCTs patients' tissue samples compared to normal testicular tissue. We characterized novel clinically relevant model of chemoresistant TGCTs, for the first time identified the ALDH1A3 as a therapeutic target in TGCTs and more importantly, showed that disulfiram represents a viable treatment option for refractory TGCTs.

Epigenetic Remodeling through Downregulation of Polycomb Repressive Complex 2 Mediates Chemotherapy Resistance in Testicular Germ Cell Tumors

A greater understanding of the hypersensitivity and curability of testicular germ cell tumors (TGCTs) has the potential to inform strategies to sensitize other solid tumors to conventional chemotherapies. The mechanisms of cisplatin hypersensitivity and resistance in embryonal carcinoma (EC), the stem cells of TGCTs, remain largely undefined. To study the mechanisms of cisplatin resistance we generated a large panel of independently derived, acquired resistant clones from three distinct parental EC models employing a protocol designed to match standard of care regimens of TGCT patients. Transcriptomics revealed highly significant expression changes shared between resistant cells regardless of their parental origin. This was dominated by a highly significant enrichment of genes normally repressed by H3K27 methylation and the polycomb repressive complex 2 (PRC2) which correlated with a substantial decrease in global H3K27me3, H2AK119 ubiquitination, and expression of BMI1. Importantly, repression of H3K27 methylation with the EZH2 inhibitor GSK-126 conferred cisplatin resistance to parental cells while induction of H3K27 methylation with the histone lysine demethylase inhibitor GSK-J4 resulted in increased cisplatin sensitivity to resistant cells. A gene signature based on H3K27me gene enrichment was associated with an increased rate of recurrent/progressive disease in testicular cancer patients. Our data indicates that repression of H3K27 methylation is a mechanism of cisplatin acquired resistance in TGCTs and that restoration of PRC2 complex function is a viable approach to overcome treatment failure.

Current medical management of patients with poor-risk metastatic germ-cell tumors

PURPOSE OF REVIEW

Despite the high cure rate of germ-cell tumors (GCTs), the 5-year survival rate for those patients with metastatic poor-risk GCT rarely exceeds 50%. The purpose of this review is to highlight past and recent discoveries in the treatment of patients with poor-risk GCT.

RECENT FINDINGS

Multiple clinical trials to optimize the management of poor-risk germ-cell cancer are ongoing. First-line phase II clinical trials of dose-dense multidrug and paclitaxel-based regimens such as accelerated bleomycin, etoposide, and cisplatin (BEP), dose-dense chemotherapy and paclitaxel, ifosfamide, and cisplatin (TIP) reported promising results. Positive phase III data are still lacking.

SUMMARY

Four cycles of BEP or Etoposide (VP16), ifosfamide, cisplatin (VIP) continue to be the standard of care in patients with poor-risk GCT. A significant disparity in patient outcome exists between high-volume and low-volume centers. Referral for centers of excellence should be considered in the management of poor-risk GCT.

Phase II study of avelumab in multiple relapsed/refractory germ cell cancer

Background Germ cell tumors (GCTs) are highly curable diseases; however, not all patients can be cured. Patients in their second relapse have especially poor prognoses. PD-L1 expression is significantly higher in GCTs than in normal testicular tissue, and high PD-L1 expression is associated with a poor prognosis. This study aimed to determine the efficacy and safety of avelumab, a PD-L1 inhibitor, in patients with GCTs. Methods In this phase 2 study, patients with multiple relapsed and/or refractory GCTs were treated with avelumab at a dose of 10 mg/kg administered biweekly until progression or unacceptable toxicity. The primary endpoint was 12-week progression-free survival (PFS). Fifteen evaluable patients had to be enrolled in the first cohort, and if <8 of 15 patients had 12-week PFS, the study was to be terminated. Here, we report the results of the first stage of the trial. Results From November 2017 to January 2018, 8 patients with a median age of 29 years (range, 22 to 52 months) were enrolled. Patients were pretreated with a median of 5 (range, 1 to 6) previous lines of platinum-based therapies; 5 tumors (62.5%) were absolutely refractory to cisplatin, and 5 patients (62.5%) had visceral nonpulmonary metastases. At a median follow-up period of 2.6 months (range, 0.3 to 14.4), all the patients experienced disease progression, and 7 patients (87.5%) died. The twelve-week PFS was 0%, median PFS was 0.9 months (95% CI 0.5-1.9), and median OS was 2.7 months (95% CI 1.0-3.3). Avelumab was well tolerated, and no severe adverse events were observed. Conclusions This study failed to achieve its primary endpoint. Our data suggest a lack of avelumab efficacy in unselected multiple relapsed/refractory GCTs.

Expression of the immune checkpoint receptor TIGIT in seminoma

A characteristic feature of testicular seminoma is the abundance of immune cells in the tumor microenvironment, raising the possibility that immune checkpoint inhibitors may serve as a therapeutic option in these types of tumors. T cell immunoreceptor with Ig and ITIM domains (TIGIT) is an inhibitory immune checkpoint receptor in analogy to PD-1, and drugs targeting TIGIT are currently being investigated in clinical trials. Little is known about the expression of these proteins in testicular seminomas. Therefore the present study performed immunohistochemical analysis to determine the relative abundance of TIGIT and PD-1 in relation to the total CD3⁺ immune cell infiltration in a tissue microarray (TMA) constructed from 78 seminoma patients. The fraction of TIGIT⁺ and PD-1⁺ lymphocytes was highly variable in individual cancers and ranged from 2.3 to 69.4% (mean: 32.2±14.7%) for TIGIT and from 0.8 to 56.5% (mean: 21.6±13.2%) for PD-1. The same high degree of variability was also identified for the ratio of PD-1 to TIGIT positive cells, which varied from a dominance of TIGIT (PD-1: TIGIT ratio=0.02) in 74% of patients, to a predominance of PD-1 (PD-1: TIGIT ratio=12.5) in 23% of patients. In summary, the immune checkpoint receptors TIGIT and PD-1 are abundantly expressed in human seminomas. Once available, anti-TIGIT antibodies, possibly in combination with anti-PD-1 drugs, may be a reasonable therapeutic strategy for this type of cancer.

Two-stage optimal designs with survival endpoint when the follow-up time is restricted

BACKGROUND

Survival endpoint is frequently used in early phase clinical trials as the primary endpoint to assess the activity of a new treatment. Existing two-stage optimal designs with survival endpoint either over estimate the sample size or compute power outside the alternative hypothesis space.

METHODS

We propose a new single-arm two-stage optimal design with survival endpoint by using the one-sample log rank test based on exact variance estimates. This proposed design with survival endpoint is analogous to Simon's two-stage design with binary endpoint, having restricted follow-up.

RESULTS

We compare the proposed design with the existing two-stage designs, including the two-stage design with survival endpoint based on the nonparametric Nelson-Aalen estimate, and Simon's two-stage designs with or without interim accrual. The new design always performs better than these competitors with regards to the expected total study length, and requires a smaller expected sample size than Simon's design with interim accrual.

CONCLUSIONS

The proposed two-stage minimax and optimal designs with survival endpoint are recommended for use in practice to shorten the study length of clinical trials.

Primary Seminoma Localized in Mediastinum: Case Report

BACKGROUND

Primary mediastinal seminomas most commonly occur in young men, and they are localised in the anterior mediastinum.

CASE PRESENTATION

The presented study is a case report of a 34-year-old man suffering from a mediastinal tumour in size of 19 cm, with pleural and pericardial effusion. The patient complains of cough, difficulty breathing, weight loss, and pronounced tiredness. CT of lungs and biopsy of the mediastinal change was performed. The histopathological analysis was in favour of a primary mediastinal seminoma. The patient initially had pronouncedly increased levels of LDH and β-hCG tumour marker. Pericardiocentesis was realised due to threatening tamponade of the heart, followed by 4 cycles of chemotherapy by BEP protocol. Following 2 cycles of chemotherapy, normalisation of LDH and β-HCG levels and significantly improved the clinical condition in the patient was found. Upon completion of 4 chemotherapy cycles by BEP protocol, the patient performed an FDG-PET scan with partial response and reduced dimension of a primary tumour in the mediastinum. Radiotherapy of residual tumour mass up to a total dose of 40Gy in 20 fractions was realised. Control FDG-PET scan had a finding of complete response to a tumour and absence of FDG uptake. The last follow-up examination was performed in October 2018, and the patient was disease-free for 54 months.

CONCLUSION

Multimodality treatment approach of chemotherapy followed by radiation consolidation ensured long-term survival in primary advanced mediastinal seminoma.

Molecular Mechanisms of Cisplatin Chemoresistance and Its Circumventing in Testicular Germ Cell Tumors

PURPOSE OF REVIEW

Testicular germ cell tumors (TGCTs) represent the most common solid tumors affecting young men. Majority of TGCTs respond well to cisplatin-based chemotherapy. However, patients with refractory disease have limited treatment modalities associated with poor prognosis. Here, we discuss the main molecular mechanisms associated with acquired cisplatin resistance in TGCTs and how their understanding might help in the development of new approaches to tackle this clinically relevant problem. We also discuss recent data on the strategies of circumventing the cisplatin resistance from different tumor types potentially efficient also in TGCTs.

RECENT FINDINGS

Recent data regarding deregulation of various signaling pathways as well as genetic and epigenetic mechanisms in cisplatin-resistant TGCTs have contributed to understanding of the mechanisms related to the resistance to cisplatin-based chemotherapy in these tumors. Understanding of these mechanisms enabled explaining why majority but not all TGCTs patients are curable with cisplatin-based chemotherapy. Moreover, it could lead to the development of more effective treatment of refractory TGCTs and potentially other solid tumors resistant to platinum-based chemotherapy. This review provides additional insights into mechanisms associated with cisplatin resistance in TGCTs, which is a complex phenomenon, and there is a need for novel modalities to overcome it.

The prognostic value of DNA damage level in peripheral blood lymphocytes of chemotherapy-naïve patients with germ cell cancer

Germ cell tumors (GCTs) are extraordinarily sensitive to cisplatin (CDDP)-based chemotherapy. DNA damage represents one of the most important factors contributing to toxic effects of CDDP-based chemotherapy. This study was aimed to evaluate the prognostic value of DNA damage level in peripheral blood lymphocytes (PBLs) from chemo-naïve GCT patients. PBLs isolated from 59 chemotherapy-naïve GCT patients were included into this prospective study. DNA damage levels in PBLs were evaluated by the Comet assay and scored as percentage tail DNA by the Metafer-MetaCyte analyzing software. The mean ± SEM (standard error of the mean) of endogenous DNA damage level was 5.25 ± 0.64. Patients with DNA damage levels lower than mean had significantly better progression free survival (hazard ratio [HR] = 0.19, 95% CI (0.04 – 0.96), P = 0.01) and overall survival (HR = 0.00, 95% CI (0.00 – 0.0), P < 0.001) compared to patients with DNA damage levels higher than mean. Moreover, there was significant correlation between the DNA damage level and presence of mediastinal lymph nodes metastases, IGCCCG (International Germ Cell Cancer Collaborative Group) risk group, and serum tumor markers level. These data suggest that DNA damage levels in PBLs of GCT patients may serve as an important prognostic marker early identifying patients with poor outcome.

Treatment of CD30-Expressing Germ Cell Tumors and Sex Cord Stromal Tumors with Brentuximab Vedotin: Identification and Report of Seven Cases

BACKGROUND

Cytotoxic therapy for relapsed and refractory germ cell tumors or metastatic sex cord stromal tumors is rarely effective and is often accompanied by high adverse event rates. Expression of CD30 has been observed in testicular cancers, and patients with CD30-expressing embryonal carcinomas have worse progression-free survival and overall survival than those with CD30-negative tumors. The objective of this study (NCT01461538) was to characterize the antitumor activity of brentuximab vedotin in patients with CD30-expressing nonlymphomatous malignancies. Enrolled patients included seven patients with relapsed or refractory germ cell tumors or metastatic sex cord stromal tumors described in this case series.

MATERIALS AND METHODS

Forty patients with relapsed or refractory germ cell tumors, metastatic sex cord stromal tumors, or testicular tumors were screened for CD30 expression; 14 patients had tumors that expressed CD30. Seven patients with CD30-expressing testicular cancer were enrolled in the treatment study: five patients with germ cell tumors, one patient with a Leydig cell tumor, and one patient with a Sertoli cell tumor. Patients were treated with brentuximab vedotin at initial doses of 1.8 or 2.4 mg/kg every 3 weeks. Response assessments were performed at cycles 2 and 4 and every 4 cycles thereafter while the patient was receiving treatment.

RESULTS

Two of seven patients achieved an objective response, including one durable complete response and one partial response at a single time point. Both responding patients had germ cell tumors. Treatment with brentuximab vedotin was generally well tolerated.

CONCLUSION

Treatment of relapsed or refractory germ cell tumors with brentuximab vedotin can induce durable responses with a manageable toxicity profile.

IMPLICATIONS FOR PRACTICE

This case series of seven patients with relapsed or refractory CD30-expressing germ cell tumors (GCTs) or sex cord stromal tumors demonstrates that brentuximab vedotin has activity against GCTs and is well tolerated in heavily pretreated patients with these aggressive tumor types. One patient achieved a complete response that has been durable for almost 4 years since the discontinuation of treatment with brentuximab vedotin. Therefore, brentuximab vedotin may be a valuable option for physicians who care for this difficult-to-treat patient population.

Prognostic role of programmed-death ligand 1 (PD-L1) expressing tumor infiltrating lymphocytes in testicular germ cell tumors

PURPOSE

Testicular germ cell tumors (TGCTs) are nearly universally curable malignancies. Nevertheless, standard cisplatin-based chemotherapy is not curative in a small subgroup of patients. Previously, we showed that PD-L1 overexpression is associated with worse prognosis in TGCTs, while tumor infiltrating lymphocytes (TILs) are prognostic in different types of cancer. This study aimed to evaluate the prognostic value of PD-1 and PD-L1 expressing TILs in TGCTs.

RESULTS

PD-L1 positive TILs were found significantly more often in seminomas (95.9% of patients) and embryonal carcinomas (91.0%) compared to yolk sac tumors (60.0%), choriocarcinomas (54.5%) or teratomas (35.7%) (All p < 0.05). TGCTs patients with high infiltration of PD-L1 positive TILs (HS ≥ 160) had significantly better progression-free survival (HR = 0.17, 95% CI 0.09 - 0.31, p = 0.0006) and overall survival (HR = 0.08, 95% CI 0.04 - 0.16, p = 0.001) opposite to patients with lower expression of PD-L1 (HS < 150). PD-1 expressing TILs were not prognostic in TGCTs.

MATERIALS AND METHODS

Surgical specimens from 240 patients with primary TGCTs were included into this translational study. The PD-1 and PD-L1 expression on tumor and TILs were detected by immunohistochemistry using anti-PD-1 and anti-PD-L1 monoclonal antibody. Scoring was performed semiquantitatively by weighted histoscore (HS) method.

CONCLUSIONS

The prognostic value of PD-L1 expressing TILs in TGCTs was demonstrated for the first time.

Epigenetic Targeting of Platinum Resistant Testicular Cancer

The involvement of epigenetic aberrations in the development and progression of tumors is now well established. However, little is known of the epigenetic alterations in testicular cancer and particularly in platinum refractory germ cell tumors. Germ cell derived testicular cancers, as compared to somatic tumors, appear to have a unique epigenetic profile that features more extensive DNA hypomethylation. Emerging data from clinical specimens suggest that epigenetic aberrations, especially DNA hypermethylation, can contribute to chemotherapy resistance and poor clinical outcomes in testicular germ cell tumors. Recent data indicate that testicular cancer cells, even those resistant to platinum, are highly sensitive to low doses of demethylating agents. Based on these promising preclinical studies, we suggest that DNA methylation inhibitors in combination with chemotherapeutic agents may offer a path to overcome acquired drug resistance in testicular cancer, laying the foundation and rationale for testing this class of epigenetic drugs in the clinical setting. In this mini-review we provide a brief overview of the promise of DNA methylation therapy to treat patients with refractory cancer of the testes.

Salvage Therapy for Patients With Germ Cell Tumor

The introduction of cisplatin combination chemotherapy, 40 years ago, transformed metastatic testicular germ cell tumors from an almost uniformly fatal disease into a model for a curable neoplasm. Before the era of platinum combination chemotherapy, the 5-year survival rate among men with metastatic testicular germ cell tumors was 5% to 10%. Currently, the 5-year survival rate is 80% for patients with metastatic disease and 95% overall. Despite the substantial advances in the treatment of germ cell tumors, 20% to 30% of patients will relapse after first-line chemotherapy and will require additional salvage therapies. Standard-dose or high-dose chemotherapy can cure ≤ 50% of these patients. Relapses after high-dose chemotherapy generally carry a poor prognosis; however, cure is still possible in a small percentage of patients by using further salvage chemotherapy or salvage surgery.

Consensus Recommendations from the Spanish Germ Cell Cancer Group on the Use of High-dose Chemotherapy in Germ Cell Cancer

BACKGROUND

High-dose chemotherapy (HDCT) has been studied in several clinical scenarios in advanced germ cell cancer (GCC).

OBJECTIVE

To establish a clinical practice guideline for HDCT use in the treatment of GCC patients.

DESIGN, SETTING, AND PARTICIPANTS

An expert panel reviewed information available from the literature. The panel addressed relevant issues concerning and related to HDCT. The guideline was externally reviewed by two international experts.

RESULTS AND LIMITATIONS

The efficacy of HDCT has been demonstrated in selected GCC patients. The most conclusive evidence comes from retrospective analyses that need to be interpreted with caution. HDCT can cure a significant proportion of heavily treated GCC patients. When indicated, sequential HDCT with regimens containing carboplatin and etoposide, as well as peripheral stem-cell support, is recommended. There is no conclusive evidence to recommend HDCT as first-line therapy. According to a multinational retrospective pooled analysis, HDCT might be superior to conventional CT as first salvage treatment in selected patients. There is an urgent need for prospective clinical trials addressing the value of HDCT in GCC patients who experience failure on first-line cisplatin-based CT. In patients who progress on conventional-dose salvage CT, HDCT should be considered. Treatment of these patients at experienced centers is strongly recommended.

CONCLUSIONS

It has been demonstrated that HDCT cures selected GCC patients who experience disease progression on conventional rescue regimens. The panel recommends the inclusion of GCC patients in randomized clinical trials including HDCT.

PATIENT SUMMARY

This consensus establishes clinical practice guidelines for the use and study of high-dose chemotherapy in patients with germ cell cancer.

Intensity modulated radiation therapy to treat primary female mediastinal seminoma and massive pericardial effusion: A case report

Primary mediastinal seminoma is a rare extragonadal germ cell tumour that mainly occurs in males. The present study reports the case of a 27-year-old woman that presented with superior vena cava syndrome and a large mass in the mediastinum, which was diagnosed as primary female mediastinal seminoma. The patient received 6 cycles of cisplatin-based chemotherapy [4 cycles BEP chemotherapy (120 mg cisplatin, 0.45 g etoposide and 60 mg bleomycin, once every 3 weeks); 2 cycles IEP chemotherapy (120 mg cisplatin, 100 mg epirubicin and 6 g ifosfamide, once every 3 weeks)] and the patient showed an increase in the size of the mediastinal mass and hydropericardium, indicating a resistance to chemotherapy. Radiotherapy to the mediastinum (50 Gy over 18 fractions) and pericardium (30 Gy over 18 fractions) was performed. Following radiotherapy, the patient was considered to have a complete response to the treatment, and subsequent to a 5-year follow-up, no recurrence or metastasis was identified. To the best of our knowledge, no similar cases have been reported in the literature at present.

Refractory testicular germ cell tumors are highly sensitive to the second generation DNA methylation inhibitor guadecitabine

Testicular germ cell tumors (TGCTs) are the most common cancers of young males. A substantial portion of TGCT patients are refractory to cisplatin. There are no effective therapies for these patients, many of whom die from progressive disease. Embryonal carcinoma (EC) are the stem cells of TGCTs. In prior in vitro studies we found that EC cells were highly sensitive to the DNA methyltransferase inhibitor, 5-aza deoxycytidine (5-aza). Here, as an initial step in bringing demethylation therapy to the clinic for TGCT patients, we evaluated the effects of the clinically optimized, second generation demethylating agent guadecitabine (SGI-110) on EC cells in an animal model of cisplatin refractory testicular cancer. EC cells were exquisitely sensitive to guadecitabine and the hypersensitivity was dependent on high levels of DNA methyltransferase 3B. Guadecitabine mediated transcriptional reprogramming of EC cells included induction of p53 targets and repression of pluripotency genes. As a single agent, guadecitabine completely abolished progression and induced complete regression of cisplatin resistant EC xenografts even at doses well below those required to impact somatic solid tumors. Low dose guadecitabine also sensitized refractory EC cells to cisplatin in vivo. Genome-wide analysis indicated that in vivo antitumor activity was associated with activation of p53 and immune-related pathways and the antitumor effects of guadecitabine were dependent on p53, a gene rarely mutated in TGCTs. These preclinical findings suggest that guadecitabine alone or in combination with cisplatin is a promising strategy to treat refractory TGCT patients.

MGMT and CALCA promoter methylation are associated with poor prognosis in testicular germ cell tumor patients

Testicular germ cell tumors (TGCT) represent the second main cause of cancer-related death in young men. Despite high cure rates, refractory disease results in poor prognosis. Epigenetic reprogramming occurs during the development of seminomas and non-seminomas. Understanding the molecular and genetic basis of these tumors would represent an important advance in the search for new TGCT molecular markers. Hence the frequency of methylation of a gene panel (VGF, MGMT, ADAMTS1, CALCA, HOXA9, CDKN2B, CDO1 and NANOG) was evaluated in 72 primary TGCT by quantitative methylation specific PCR. A high frequency of MGMT (90.9%, 20/22; p=0.019) and CALCA (90.5%, 19/21; p<0.026) methylation was associated with non-seminomatous tumors while CALCA methylation was also associated with refractory disease (47.4%, 09/19; p=0.005). Moreover, promoter methylation of both genes predicts poor clinical outcome for TGCT patients (5-year EFS: 50.5% vs 77.1%; p=0.032 for MGMT and 51.3% vs 77.0%; p=0.029 for CALCA). The findings of this study indicate that methylation of MGMT and CALCA are frequent and could be used as new molecular markers of prognosis in TGCT.

Prognostic value of programmed-death-1 receptor (PD-1) and its ligand 1 (PD-L1) in testicular germ cell tumors

BACKGROUND

Testicular germ cell tumors (TGCTs) belong to the most chemosensitive solid tumors; however, a small proportion of patients fail to be cured with cisplatin-based chemotherapy. Inhibitors of PD-1/PD-L1 pathways represent a new class of promising drugs in anticancer therapy. The aim of this study was to evaluate expression and prognostic value of PD-1 and PD-L1 in TGCTs.

PATIENTS AND METHODS

Surgical specimens from 140 patients with TGCTs (131 with primary testicular tumor and 9 with extragonadal GCTs) were included into the translational study. PD-1 and PD-L1 expression was detected in the tumor tissue by immunohistochemistry using monoclonal antibodies, scored by the multiplicative quickscore (QS) method, compared with their expression in normal testicular tissue and correlated with clinicopathological characteristics and clinical outcome.

RESULTS

None of the GCTs exhibited PD-1 protein, although expression of PD-L1 was significantly higher in GCTs in comparison with normal testicular tissue (mean QS = 5.29 versus 0.32, P < 0.0001). Choriocarcinomas exhibit the highest level of PD-L1 with decreasing positivity in embryonal carcinoma, teratoma, yolk sac tumor and seminoma. PD-L1 expression was associated with poor prognostic features, including ≥3 metastatic sites, increased serum tumor markers and/or non-pulmonary visceral metastases. Patients with low PD-L1 expression had significantly better progression-free survival [hazard ratio (HR) = 0.40, 95% confidence interval (CI) 0.16-1.01, P = 0.008] and overall survival (HR = 0.43, 95% CI 0.15-1.23, P = 0.040) compared with patients with high PD-L1 expression.

CONCLUSIONS

In this translational study, we showed, for the first time, the prognostic value of PD-L1 expression in TGCTs and our data imply that the PD-1/PD-L1 pathway could be a novel therapeutic target in TGCTs.

Phase II study of everolimus in refractory testicular germ cell tumors

BACKGROUND

Testicular germ cell tumors (TGCTs) represent a highly curable disease; however, a small proportion of patients develop disease recurrence. Loss of the tumor-suppressor gene phosphatase and tensin homolog marks the transition from intratubular germ cell neoplasia to invasive GCT and is correlated with disease progression. Inactivation of phosphatase and tensin homolog is associated with deregulation of the PI3K/Akt pathway and increased mammalian target of rapamycin signaling. This study aimed to determine the efficacy and toxicity of a mammalian target of rapamycin inhibitor, everolimus, in patients with refractory TGCTs.

METHODS

From December 2011 to February 2015, 15 patients with refractory GCTs were enrolled in the phase II study. All patients were pretreated with at least 2 cisplatin-based therapies; 4 tumors (26.7%) were absolutely refractory to cisplatin and 9 patients (60.0%) had visceral nonpulmonary metastases. Everolimus was administered at a dose of 10mg daily until progression or unacceptable toxicity. The primary end point was the objective response rate, according to Response Evaluation Criteria in Solid Tumors.

RESULTS

No objective response was observed, but 6 patients (40.0%) achieved 12-week progression-free survival. During a median follow-up period of 3.6 months (range: 1-35.1mo), all patients experienced disease progression and 11 patients (80.0%) died. Median progression-free survival was 1.7 months (95% CI: 1.1-4.0mo) and median overall survival was 3.6 months (95% CI: 2.0-11.0mo).

CONCLUSIONS

This study failed to achieve its primary end point and our data suggest limited efficacy of everolimus against unselected heavily pretreated refractory TGCTs.

CONDENSED ABSTRACT

Everolimus showed limited efficacy in unselected heavily pretreated refractory TGCTs. Prolonged disease stabilization could be achieved in selected patients.

All-trans retinoic acid inhibits proliferation, migration, invasion and induces differentiation of hepa1-6 cells through reversing EMT in vitro

Hepatocellular carcinoma (HCC) has the characristics of tumor invasiveness, frequent intrahepatic spread and extra hepatic metastases, which affects the therapy efficiency and prognosis. Epithelial-mesenchymal transition (EMT) is now recognized as a key process in tumor invasion, metastasis and the generation of cancer initiating cells. All-trans retinoic acid (ATRA) is currently used as a potential chemo-therapeutic or chemo-preventive agent because of its anti-proliferative, pro-apoptotic and antioxidant properties. This study investigated the effects of ATRA at different concentrations on the proliferation, migration, invasion, differentiation and functions of the mouse hepa1-6 hepatocarcinoma cell line and explored whether ATRA regulates EMT in the antitumor process. Trypan blue staining and colony formation assay were used to detect cell proliferation. Wound-healing assay and Transwell Matrigel assay were performed to examine migration. Invasion was assessed by using Transwell invasion assay. In the present study, ATRA significantly inhibited the cell growth, colony formation, migration, and invasion capability of hepa1-6 cells in a dose-dependent manner. Furthermore, ATRA at low concentration (0.1 µmol/l) could generate these influences. After treated in the ATRA medium, the expression of mature hepatic markers ALB (albumin), CK18 (cytokeratin 18), TAT (tyrosine aminotransferase), ApoB (apolipoprotein B) decreased and that of hepatocarcinoma marker AFP (α fetoprotein) increased. At day 7 after ATRA induction, hepa1-6 cells showed comparable indocyanine green (ICG) uptake and glycogen storage function to the blank control. The mRNA expression of mesenchymal markers N-cadherin, vimentin, snail and twist decreased, while expression of epithelial marker E-cadherin increased in hepa1-6 cells after treated with ATRA. Therefore, this study demonstrates that ATRA remarkably suppressed the proliferation, migration, invasion of hepa1-6 hepatocarcinoma cell line and effectively induced its differentiation and liver functions in vitro through the reversal of EMT. HCC may be more sensitive to ATRA than other cancers, suggesting the prospective usefulness of ATRA in the treatment of HCC.

Salvage therapy in patients with germ cell tumors

Testicular cancer is the most curable metastatic solid tumor. Initial chemotherapy is evidence based with risk stratification into three prognostic categories: good, intermediate, and advanced disease. Guidelines for disease management following progression after initial cisplatin combination chemotherapy are less clear. Options include salvage surgery for patients with anatomically confined relapse, standard-dose cisplatin combination chemotherapy, or high-dose chemotherapy with carboplatin plus etoposide with peripheral blood stem cell transplantation. Proper interpretation of a presumed relapse can be complicated. Growing masses on imaging studies might reflect a growing teratoma. Persistent elevations of serum human chorionic gonadotropin (hCG) or alpha fetoprotein (AFP) are only an indication for salvage therapy if there is a definitive rise in the tumor marker. Elevated and rising serum hCG as the only evidence of recurrence can be because of cross reactivity with luteinizing hormone or usage of marijuana rather than progressive cancer. Elevated liver function tests can cause rising serum AFP.

Phase 2 trial of the cyclin-dependent kinase 4/6 inhibitor palbociclib in patients with retinoblastoma protein-expressing germ cell tumors

BACKGROUND

Alterations in the retinoblastoma pathway in germ cell tumors (GCTs) have been described. In the phase 1 trials of the selective cyclin-dependent kinase 4/6 inhibitor palbociclib, 3 patients with unresectable, growing, mature teratoma syndrome achieved prolonged disease stabilization. The authors conducted an open-label, phase 2 study to determine the efficacy and safety of palbociclib in patients with incurable, refractory, retinoblastoma protein (pRB)-expressing GCTs.

METHODS

Patients who had incurable, refractory GCTs that demonstrated pRB expression by immunohistochemistry received oral palbociclib 125 mg daily for 21 days followed by a 7-day break. The primary endpoint was the 24-week progression-free survival (PFS) rate. A 24-week PFS rate ≥15% was considered promising, and a PFS rate ≤5% was not considered promising.

RESULTS

Thirty patients received treatment, and 29 were evaluable for the primary endpoint. The estimated 24-week PFS rate was 28% (90% exact confidence interval, 15%-44%). Patients who had teratoma and teratoma with malignant transformation had significantly better PFS than patients who had nonteratomatous GCTs. Toxicity was manageable and was principally hematologic.

CONCLUSIONS

Treatment with palbociclib was associated with a favorable 24-week PFS rate in patients with refractory, pRB-expressing GCTs. Benefit was mainly observed in patients who had unresectable teratomas and teratomas with malignant transformation.

Cryptogenic subtype predicts reduced survival among cancer patients with ischemic stroke

BACKGROUND AND PURPOSE

Cryptogenic stroke is common in patients with cancer. Autopsy studies suggest that many of these cases may be because of marantic endocarditis, which is closely linked to cancer activity. We, therefore, hypothesized that among patients with cancer and ischemic stroke, those with cryptogenic stroke would have shorter survival.

METHODS

We retrospectively analyzed all adult patients with active systemic cancer diagnosed with acute ischemic stroke at a tertiary care cancer center from 2005 through 2009. Two neurologists determined stroke mechanisms by consensus. Patients were diagnosed with cryptogenic stroke if no specific mechanism could be determined. The diagnosis of marantic endocarditis was restricted to patients with cardiac vegetations on echocardiography or autopsy and negative blood cultures. Patients were followed until July 31, 2012, for the primary outcome of death. Kaplan-Meier statistics and the log-rank test were used to compare survival between patients with cryptogenic stroke and patients with known stroke mechanisms. Multivariate Cox proportional hazard analysis evaluated the association between cryptogenic stroke and death after adjusting for potential confounders.

RESULTS

Among 263 patients with cancer and ischemic stroke, 133 (51%) were cryptogenic. Median survival in patients with cryptogenic stroke was 55 days (interquartile range, 21-240) versus 147 days (interquartile range, 33-735) in patients with known stroke mechanisms (P<0.01). Cryptogenic stroke was independently associated with death (hazard ratio, 1.64; 95% confidence interval, 1.25-2.14) after adjusting for age, systemic metastases, adenocarcinoma histology, and functional status.

CONCLUSIONS

Cryptogenic stroke is independently associated with reduced survival in patients with active cancer and ischemic stroke.

All-transretinoic acid ameliorates bleomycin-induced lung fibrosis by downregulating the TGF-β1/Smad3 signaling pathway in rats

The transforming growth factor-β1 (TGF-β1)/Smad3 signaling pathway has a central role in pathogenesis of lung fibrosis. In the present study, we investigated if all-trans retinoic acid (ATRA) could attenuate fibrosis in bleomycin (BLM)-induced lung fibrosis in rats through regulating TGF-β1/Smad3 signaling. Beginning on day 14 after BLM administration, the ATRA I and II groups of rats received daily oral administration of ATRA for 14 days. All rats were killed on day 28. Lung tissue sections were prepared and subject to histological assessment, and expression levels of proteins involved in the TGF-β1 signaling cascade and epithelial-mesenchymal transition (EMT) were evaluated by transmission electron microscopy (TEM), quantitative real-time polymerase chain reaction (qRT-PCR), western blot procedure, and immunohistochemical or immunofluorescence staining. BLM significantly increased the alveolar septum infiltrates, inflammatory cell infiltrates, and collagen fibers. These BLM-induced changes were significantly ameliorated by ATRA treatment. In addition, BLM significantly increased levels of lung fibrosis markers α-SMA, hydroxyproline (Hyp), collagen I, Snail, and Twist, whereas significantly decreased E-cadherin expression. ATRA treatment largely reversed BLM-induced changes in these lung fibrosis markers. ATRA also blocked BLM-induced activation of the TGF-β1/Smad3 signaling pathway in lung tissues, including expression of TGF-β1, Smad3, p-Smad3, zinc-finger E-box-binding homeobox 1 and 2 (ZEB1 and ZEB2), and the high-mobility group AT-hook 2 (HMGA2). Our results suggest that ATRA may have potential therapeutic value for lung fibrosis treatment.

Persistent CD30 expression by embryonal carcinoma in the treatment time course: prognostic significance of a worthwhile target for personalized treatment

PURPOSE

CD30 is expressed by untreated embryonal carcinoma, supporting the rationale for a targeted approach. However, the reported chemotherapy induced switching off of CD30 noted on immunohistochemistry may affect its therapeutic potential for disease relapse. We evaluated persistent CD30 expression and its prognostic meaning in cases of post-chemotherapy residual disease.

MATERIALS AND METHODS

Paraffin blocks of surgical samples that yielded nonteratomatous viable cells after 1 or more cisplatin based chemotherapy treatments were retrieved and reassessed by 2 pathologists blinded to the study purpose. Multivariable analysis was done for prespecified factors.

RESULTS

A total of 49 cases of pure embryonal carcinoma or mixed germ cell tumor from August 1991 to August 2012 had full clinical data and suitable tissue available for analysis. Of the 35 cases (71.4%, 95% CI 56.7-83.4) with preserved CD30 positivity 14 (40.0%) showed residual disease after a median of 1 regimen (IQR 1-2). Five-year overall survival in CD30 positive and negative cases was 37.0% (95% CI 22.1-61.8) and 50.1% (95% CI 27.9-90.0, p=0.078), while after first line treatment it was 23.2% (95% CI 8.6-62.5) and 47.6% (95% CI 18.8-100, p=0.025), respectively. On multivariable analysis CD30 positivity was a significant prognostic factor for progression-free survival (HR 2.32, 95% CI 1.04-5.19) and overall survival (HR 2.77, 95% CI 1.05-7.29).

CONCLUSIONS

CD30 was retained even after an intensive pretreatment load, confirming that it is a reliable treatment target. Its expression was associated with a significantly poorer prognosis in multiple relapse/chemoresistant cases and it was an independent prognostic factor for survival.