Intratumoral heterogeneity: Role of differentiation in a potentially lethal phenotype of testicular cancer

Prognostic value of 18F-FDG PET radiomics and sarcopenia in patients with oral squamous cell carcinoma

BACKGROUND

Oral cancer is one of the most common malignancies in the head and neck region. Approximately 90% of oral cancers are oral squamous cell carcinomas (OSCC). 18F-FDG PET/CT has been used in OSCC patients for its high value in detecting metastatic lymph nodes and distant metastases. PET radiomics and sarcopenia can be measured on the PET and CT components of 18F-FDG PET/CT.

PURPOSE

This study aimed to investigate the prognostic value of radiomics and sarcopenia measured on the PET and CT components of pre-operation 18F-FDG PET/CT in OSCC.

METHODS

A total of 116 patients eventually enrolled in our study were randomly divided into two cohorts: training cohort (n = 58) and validation cohort (n = 58). The Cox model combined with the least absolute shrinkage and selection operator (LASSO) algorithm was applied to construct the radiomics score (Rad_score). The third lumber skeletal muscle index (L3 SMI) was calculated to identify sarcopenia. Univariate and multivariate Cox regression analyses were performed to identify the independent prognostic factors. Based on the clinical factors, the clinical model was constructed, and the combined model was developed through the combination of the clinical model and Rad_score. C index, time-dependent C-index curves, receiver operating characteristic (ROC) curve, calibration curves, and decision curve analysis were used to evaluate the performance of prediction models.

RESULTS

Three radiomics features constitute the Rad_score for overall survival (OS) and progression-free survival (PFS), respectively. Multivariate Cox regression analysis revealed that Rad_score was an independent prognostic factor, whereas sarcopenia was not. The combined models showed satisfactory performance in both the training cohort (C-index: OS:0.836, PFS:0.776) and the validation cohort (C-index: OS:0.744, PFS:0.712). The combined models were visualized as nomograms. Nomogram scores can realize the risk stratification of OSCC patients. Lower nomogram score is significantly related to the poorer OS (training cohort: p < 0.0001, validation cohort: p < 0.0001, overall cohort: p < 0.0001) and PFS (training cohort: p < 0.0001, validation cohort: p = 0.00017, overall cohort: p < 0.0001).

CONCLUSIONS

Rad_score, but not sarcopenia, was an independent prognostic factor for patients with OSCC. The nomograms had a satisfactory performance, which might be helpful for OSCC patients and clinicians in personalized prognostic prediction and treatment decision-making.

Germ Cell Tumor of the Testis: Lethal Subtypes of a Curable Cancer

Germ cell tumor of the testis (GCT) is a curable cancer even when it is widely metastatic; however, outcomes can differ based on tumor histology. Chemo-resistance in certain phenotypes, such as teratoma and yolk sac tumor, contributes to poor clinical outcomes in some patients with GCT. Despite this resistance to S-YSTemic therapy, many of these tumor subtypes remain amenable to surgical resection and possible cure. In this study, we report on a series of seven patients highlighting two chemo-resistant subtypes of nonseminomatous germ cell tumor (NSGCT), sarcomatoid yolk sac tumor (S-YST), and epithelioid trophoblastic tumor (ETT) for which early resection rather than additional salvage chemotherapy or high-dose intense chemotherapy might provide a superior clinical outcome and enhance cure rate.

Intratumoral Heterogeneity, Chemoresistance and Lymph Node Landing Zone Prognosis in Testicular Tumors Based on Histopathological Characteristics

BACKGROUND

Existing data on the histopathological correlation of testicular tumors with lymph node prognosis have been poorly explored. We aimed to investigate the relationship of the histopathological properties of testicular tumors with lymph nodes and their involvement with chemoresistance and heterogeneity of testicular tumors.

METHODS

Patients with non-seminomatous germ cell tumor (NSGCT) were selected for histopathological correlation of testicular tumor with lymph nodes and its relationship with chemoresistance and heterogeneity. Histopathological and radiological parameters associated with the risk of chemoresistance and tumor progression were measured pre- and post-chemotherapy. Binomial logistic regression and Kaplan-Meier analysis were implemented to determine the predictors of progression and adverse overall patient survival. All categorical variables were analyzed using the Chi-square test, while Pearson's R coefficient determined the correlation.

RESULTS

Male patients who were diagnosed with NSGCT from March 2017 to December 2018 at Guwahati Medical College, Guwahati, India, were included in this study. Lymph node groups were predominantly incriminated with the EYST or EYS groups and minimally linked with the pure E and YCS groups. Furthermore, the highest number of lymph node stations was associated with pre-chemotherapy. In salvage chemotherapy in the form of VIP, we found exciting outcomes, as approximately 41% of cases responded positively, especially in the EYS group.

CONCLUSION

Our study classifies NSGCT according to the most favorable histopathological grouping and explores the tumoral response in different intrinsic and extrinsic variables. Our analysis can serve as a triumphant histopathological nomogram for a sublime management protocol to deal with the onerous histological pairing in NSGCT.

Paraneoplastic neurologic syndrome and autoantibody accompaniments of germ cell tumors

Paraneoplastic neurologic syndromes (PNSs) are a group of diseases affecting the central and/or peripheral nervous system caused by immune-mediated processes directed toward antigens with shared expression in tumor and neural tissue. Germ cell tumors (GCTs) are associated with PNSs with varied clinical phenotypes. Early diagnosis of PNS is vital to potentially uncover and treat underlying tumors, improving the chances of recovery, and preventing permanent neurologic complications. In this chapter, we outline the pathophysiology and epidemiology of PNS. We briefly provide a summary of GCTs in males and females. We review the neural-specific autoantibodies and PNSs associated with GCTs and their clinical and radiologic accompaniments. We also provide an overview of the treatment and prognosis of these disorders.

Administration of a glypican-3 peptide increases the infiltration and cytotoxicity of CD8+ T cells against testicular yolk sac tumor, associated with enhancing the intratumoral cGAS/STING signaling

BACKGROUND

Glypican-3 (GPC3) is highly expressed in testicular yolk sac tumor (TYST). GPC3 has been evaluated as a cancer vaccine for some types of tumors, but little is known on the effects of GPC3 peptide-based therapy on TYST. Here, we evaluated the antitumor effect of GPC3144-152 on TYST and its potential mechanisms.

METHODS

GPC3144-152 -specific CD8+ T cells were induced by vaccine immunization and examined by ELISPOT. The CD8+ T cells were purified for testing their cytotoxicity in vitro against TYST cells by CCK-8 and TUNEL assays and in vivo against tumor growth. The influence of GPC3144-152 loading and/or cGAS silencing on the tumor growth, apoptosis and cGAS/STING signaling was tested by immunohistochemistry, immunofluorescence, flow cytometry, and Western blot.

RESULTS

Vaccination with GPC3144-152 induced tumor-specific CD8+ T cells that secreted high levels of IFN-γ and granzyme B, and had potent cytotoxicity against TYST in a dose-dependent manner. Adoptive transfer of CD8+ T cells and treatment with GPC3144-152 significantly inhibited the growth of TYST tumors, but less effective for cGAS-silenced TYST tumors in vivo. Treatment with GPC3144-152 enhanced the infiltration of CD8+ T cells into the tumor environment and their cytotoxicity against TYST tumors in vivo by up-regulating granzyme B and IFN-β expression, but down-regulating GPC3 expression in the tumors. Co-culture of CD8+ T cells with TYST in the presence of exogenous GPC3144-152 enhanced peptide-specific CD8+ T-cell cytotoxicity in vitro, accompanied by enhancing cGAS, γH2AX, TBK1, and IRF3 phosphorylation in TYST cells, but less effective in cGAS-silenced TYST cells.

CONCLUSIONS

These data indicated that GPC3 peptide-specific CD8+ T cells had potent antitumor activity against TYST tumor, particularly for combined treatment with the peptide, which was partially dependent on the intratumoral cGAS/STNG signaling. GPC3 peptide vaccine may be valuable for the combination treatment of TYST.

Stem Cell Origin of Cancer: Clinical Implications for Cancer Immunity and Immunotherapy

A simple way to understand the immune system is to separate the self from non-self. If it is self, the immune system tolerates and spares. If it is non-self, the immune system attacks and destroys. Consequently, if cancer has a stem cell origin and is a stem cell disease, we have a serious problem and a major dilemma with immunotherapy. Because many refractory cancers are more self than non-self, immunotherapy may become an uphill battle and pyrrhic victory in cancer care. In this article, we elucidate cancer immunity. We demonstrate for whom, with what, as well as when and how to apply immunotherapy in cancer care. We illustrate that a stem cell theory of cancer affects our perspectives and narratives of cancer. Without a pertinent theory about cancer's origin and nature, we may unwittingly perform misdirected cancer research and prescribe misguided cancer treatments. In the ongoing saga of immunotherapy, we are at a critical juncture. Because of the allure and promises of immunotherapy, we will be treating more patients not immediately threatened by their cancer. They may have more to lose than to gain, if we have a misconception and if we are on a wrong mission with immunotherapy. According to the stem cell theory of cancer, we should be careful with immunotherapy. When we do not know or realize that cancer originates from a stem cell and has stem-ness capabilities, we may cause more harm than good in some patients and fail to separate the truth from the myth about immunotherapy in cancer care.

Stem Cell Theory of Cancer: Origin of Metastasis and Sub-clonality

Metastasis may be the secret weapon cancer uses to dominate and subjugate, to persist and prevail. However, it is no longer a secret when we realize that a stem cell has the same ways and means to fulfill its own omnipotence and accomplish its own omnipresence… and when we realize that a cancer cell has its own version of stem-ness origin and stem-like nature. In this perspective, we discuss whether stem-ness enables metastasis or mutations drive metastasis. We ponder about low-grade versus high-grade tumors and about primary versus metastatic tumors. We wonder about stochasticity and hierarchy in the genesis and evolution of cancer and of metastasis. We postulate that metastasis may hold the elusive code that makes or breaks a stem-cell versus a genetic theory of cancer. We speculate that the vaunted model of multistep carcinogenesis may be in error and needs some belated remodeling and a major overhaul. We propose that subsequent malignant neoplasms from germ cell tumors and donor-derived malignancies in organ transplants are quintessential experiments of nature and by man that may eventually empower us to elucidate a stem-cell origin of cancer and metastasis. Unfortunately, even the best experiments of cancer and of metastasis will be left unfinished, overlooked, or forgotten, when we do not formulate a proper cancer theory derived from pertinent and illuminating clinical observations. Ultimately, there should be no consternations when we realize that metastasis has a stem-cell rather than a genetic origin, and no reservations when we recognize that metastasis has been providing us some of the most enduring tests and endearing proofs to demonstrate that cancer is indeed a stem-cell rather than a genetic disease after all.

Artificial Intelligence and Precision Medicine: A New Frontier for the Treatment of Brain Tumors

Brain tumors are a widespread and serious neurological phenomenon that can be life- threatening. The computing field has allowed for the development of artificial intelligence (AI), which can mimic the neural network of the human brain. One use of this technology has been to help researchers capture hidden, high-dimensional images of brain tumors. These images can provide new insights into the nature of brain tumors and help to improve treatment options. AI and precision medicine (PM) are converging to revolutionize healthcare. AI has the potential to improve cancer imaging interpretation in several ways, including more accurate tumor genotyping, more precise delineation of tumor volume, and better prediction of clinical outcomes. AI-assisted brain surgery can be an effective and safe option for treating brain tumors. This review discusses various AI and PM techniques that can be used in brain tumor treatment. These new techniques for the treatment of brain tumors, i.e., genomic profiling, microRNA panels, quantitative imaging, and radiomics, hold great promise for the future. However, there are challenges that must be overcome for these technologies to reach their full potential and improve healthcare.

Integrated Molecular Analysis Reveals 2 Distinct Subtypes of Pure Seminoma of the Testis

Objective

Testicular germ cell tumors (TGCT) are the most common solid malignancy in adolescent and young men, with a rising incidence over the past 20 years. Overall, TGCTs are second in terms of the average life years lost per person dying of cancer, and clinical therapeutics without adverse long-term side effects are lacking. Platinum-based regimens for TGCTs have heterogeneous outcomes even within the same histotype that frequently leads to under- and over-treatment. Understanding of molecular differences that lead to diverse outcomes of TGCT patients may improve current treatment approaches. Seminoma is the most common subtype of TGCTs, which can either be pure or present in combination with other histotypes.

Methods

Here we conducted a computational study of 64 pure seminoma samples from The Cancer Genome Atlas, applied consensus clustering approach to their transcriptomic data and revealed 2 clinically relevant seminoma subtypes: seminoma subtype 1 and 2.

Results

Our analysis identified significant differences in pluripotency stage, activity of double stranded DNA breaks repair mechanisms, rates of loss of heterozygosity, and expression of lncRNA responsible for cisplatin resistance between the subtypes. Seminoma subtype 1 is characterized by higher pluripotency state, while subtype 2 showed attributes of reprograming into non-seminomatous TGCT. The seminoma subtypes we identified may provide a molecular underpinning for variable responses to chemotherapy and radiation.

Conclusion

Translating our findings into clinical care may help improve risk stratification of seminoma, decrease overtreatment rates, and increase long-term quality of life for TGCT survivors.

Preoperative contrast-enhanced computed tomography-based radiomics model for overall survival prediction in hepatocellular carcinoma

BACKGROUND

Hepatocellular carcinoma (HCC) is the most common primary liver malignancy with a rising incidence worldwide. The prognosis of HCC patients after radical resection remains poor. Radiomics is a novel machine learning method that extracts quantitative features from medical images and provides predictive information of cancer, which can assist with cancer diagnosis, therapeutic decision-making and prognosis improvement.

AIM

To develop and validate a contrast-enhanced computed tomography-based radiomics model for predicting the overall survival (OS) of HCC patients after radical hepatectomy.

METHODS

A total of 150 HCC patients were randomly divided into a training cohort (n = 107) and a validation cohort (n = 43). Radiomics features were extracted from the entire tumour lesion. The least absolute shrinkage and selection operator algorithm was applied for the selection of radiomics features and the construction of the radiomics signature. Univariate and multivariate Cox regression analyses were used to identify the independent prognostic factors and develop the predictive nomogram, incorporating clinicopathological characteristics and the radiomics signature. The accuracy of the nomogram was assessed with the concordance index, receiver operating characteristic (ROC) curve and calibration curve. The clinical utility was evaluated by decision curve analysis (DCA). Kaplan–Meier methodology was used to compare the survival between the low- and high-risk subgroups.

RESULTS

In total, seven radiomics features were selected to construct the radiomics signature. According to the results of univariate and multivariate Cox regression analyses, alpha-fetoprotein (AFP), neutrophil-to-lymphocyte ratio (NLR) and radiomics signature were included to build the nomogram. The C-indices of the nomogram in the training and validation cohorts were 0.736 and 0.774, respectively. ROC curve analysis for predicting 1-, 3-, and 5-year OS confirmed satisfactory accuracy [training cohort, area under the curve (AUC) = 0.850, 0.791 and 0.823, respectively; validation cohort, AUC = 0.905, 0.884 and 0.911, respectively]. The calibration curve analysis indicated a good agreement between the nomogram-prediction and actual survival. DCA curves suggested that the nomogram had more benefit than traditional staging system models. Kaplan–Meier survival analysis indicated that patients in the low-risk group had longer OS and disease-free survival (all P < 0.0001).

CONCLUSION

The nomogram containing the radiomics signature, NLR and AFP is a reliable tool for predicting the OS of HCC patients.

Stem Cell Theory of Cancer: Implications for Translational Research from Bedside to Bench

A stem cell theory of cancer considers genetic makeup in the proper cellular context. It is a unified theory of cancer that unites the genome with the epigenome, links the intracellular with the extracellular, and connects the cellular constituents and compartments with the microenvironment. Although it allies with genomic medicine, it is better aligned with integrated medicine. In this perspective, we focus on translational research in cancer care. We expose some intrinsic fallacies in translational research when it relates to the basic principles of the scientific method in the care of patients with genomic medicine versus integrated medicine. We postulate that genomic medicine may be at the root of many failed efforts in drug development and data reproducibility. We propose an alternate heuristic approach that may expedite the development of safe and effective treatments and minimize the generation of unproductive pharmaceutical products and nonreproducible experimental results. Importantly, a heuristic approach emphasizes the role of a pertinent scientific theory and distinguishes therapy development from drug development, such that we discover not only useful drugs but also better ways to use them in order to optimize patient care and maximize clinical outcomes.

Very Late Recurrence in Germ Cell Tumor of the Testis: Lessons and Implications

Background. Very late recurrence (LR), i.e., >5 years after initial presentation, occurs in about 1% of patients with germ cell tumors of the testis (TGCT) and is associated with poor prognosis. Methods. We retrospectively reviewed the records of patients at the M. D. Anderson Cancer Center who developed LR > 5 years after their initial diagnosis of TGCT. Results. We identified 25 patients who developed LR between July 2007 and August 2020. The median age at the time of LR was 46 years (range, 29−61). Pathology of LR: somatic transformation to carcinoma or sarcoma—11, nonseminoma with yolk sac tumor or teratoma—11, nonseminoma without yolk sac tumor or teratoma—2, not available—1. With a median follow-up of 3.5 years, 68% of patients are alive 3 years after LR. Patients with prior post-chemotherapy consolidation surgery do not have statistically significant longer survival compared to patients who did not receive post-chemotherapy consolidation surgery, 83.3% vs. 60.8% at 3 years, respectively, p = 0.50. Conclusions. Patients with LR > 5 years tend to harbor nonseminoma (with yolk sac tumor and or teratoma). Among these patients, a majority who did not undergo surgery to remove residual disease after chemotherapy developed somatic transformation and succumbed to their LR.

Stem Cell Theory of Cancer: Rude Awakening or Bad Dream from Cancer Dormancy?

To be dormant or not depends on the origin and nature of both the cell and its niche. Similar to other cancer hallmarks, dormancy is ingrained with stemness, and stemness is embedded within dormancy. After all, cancer dormancy is dependent on multiple factors such as cell cycle arrest, metabolic inactivity, and the microenvironment. It is the net results and sum effects of a myriad of cellular interactions, interconnections, and interplays. When we unite all cancer networks and integrate all cancer hallmarks, we practice and preach a unified theory of cancer. From this perspective, we review cancer dormancy in the context of a stem cell theory of cancer. We revisit the seed and soil hypothesis of cancer. We reexamine its implications in both primary tumors and metastatic lesions. We reassess its roles in cell cycle arrest, metabolic inactivity, and stemness property. Cancer dormancy is particularly revealing when it informs us about the mysteries of late relapse, prolonged remission, and second malignancy. It is paradoxically rewarding when it delivers us the promises and power of cancer prevention and maintenance therapy in patient care.

Somatic-type Malignancies in Testicular Germ Cell Tumors: A Clinicopathologic Study of 63 Cases

The development of somatic-type malignancies (SMs) in testicular germ cell tumors (GCTs) is a rare but well-recognized phenomenon. We studied the pathologic features of 63 GCTs with SMs in the testis (n=22) or metastases (n=41) and correlated these features with clinical outcomes. The patients with SMs in the testis (median age, 26 y) were younger than those with metastatic SMs (median age, 38.5 y). The SMs consisted of carcinomas (n=21), sarcomas (n=21), primitive neuroectodermal tumors (n=15), nephroblastomas (n=3), and mixed tumors (n=3). Sarcoma was the most common SM in the testis (n=11), and most sarcomas were rhabdomyosarcomas (n=9). Carcinoma was the most common SM in metastases (n=20), and most carcinomas were adenocarcinomas (n=12). In metastases, carcinomatous SMs developed after a longer interval from the initial orchiectomy (median times, 213 mo) than sarcomatous SMs (median times, 68 mo). Patients with metastatic SMs had significantly poorer overall survival than those with SMs in the testis (5-y survival rate, 35% vs. 87%; P=0.011). Furthermore, patients with carcinomatous SMs had a significantly worse prognosis than those with sarcomatous or primitive neuroectodermal tumor SMs (5-y survival rates, 17%, 77%, and 73%, respectively; P=0.002), when the whole cohort, including testicular and metastatic SMs, were analyzed. Our results demonstrate that SMs in metastatic GCTs are associated with a significantly worse prognosis than those in the testis. Furthermore, the histologic subtype of SM has a significant effect on the clinical outcome, with the carcinomatous SM carrying the highest risk for mortality.

Late relapsing germ cell tumors with elevated tumor markers

Purpose

Late relapsing germ cell tumors (LR-GCT) are considered a rare distinct biologic entity as their clinical presentation and response to treatment is different to early recurrences. While serum tumor markers (AFP and ß-HCG) play an important role at the time of first diagnosis to correctly classify prognosis and treatment of germ cell tumors, they may not have the same significance in a late relapse situation.

Patients and methods

Thirty-seven patients with LR-GCT with elevated serum tumor markers were identified in our database. Twenty-six patients underwent primary surgical resection of the late relapsing tumor. Eleven patients received salvage chemotherapy and a post-chemotherapy residual tumor resection. Serum tumor markers, histological findings and oncological outcome were analyzed.

Results

In the histopathological specimen, viable cancer was found in 20 cases (54%) and teratoma was found in 16 cases (43%). In nine cases (24%), a somatic-type malignant transformation was present. In 19 of 37 patients (51.4%), the late relapse specimen presented a histological type of GCT, which was not present in the primary histology. Twenty-two patients (59.5%) were included in follow-up analysis. Mean and median follow-up time was 62.2 and 53 months, respectively. Seventeen patients (77.3%) suffered a relapse or had progressive disease after LR therapy. Five patients (22.7%) have been relapse-free after LR therapy (mean FU 61.6 months). Ten patients died of disease during follow-up (45.5%) and had a mean time from LR to death of 66.4 months. Eleven patients were alive at last follow-up (mean FU 62.2 months). Relapse and survival rate were similar between patients who received primary resection of LR tumor and patients who received salvage chemotherapy followed by surgery.

Conclusion

Patients with a late relapsing germ cell tumor and elevated markers have a poor prognosis and a high risk for another relapse independent on primary treatment. The histological type and aggressiveness of a late relapsing tumor cannot be predicted with serum tumor marker levels at the time of diagnosis of LR. In up to 54% of cases, primary histology did not coincide with LR histology. Therefore, we propose primary surgical resection of a late relapsing tumor if a complete resection is feasible in order to gain exact histology and tailor further treatment.

Stem Cell Theory of Cancer: Origin of Tumor Heterogeneity and Plasticity

In many respects, heterogeneity is one of the most striking revelations and common manifestations of a stem cell origin of cancer. We observe heterogeneity in myriad mixed tumors including testicular, lung, and breast cancers. We recognize heterogeneity in diverse tumor subtypes in prostate and kidney cancers. From this perspective, we illustrate that one of the main stem-ness characteristics, i.e., the ability to differentiate into diverse and multiple lineages, is central to tumor heterogeneity. We postulate that cancer subtypes can be meaningless and useless without a proper theory about cancer's stem cell versus genetic origin and nature. We propose a unified theory of cancer in which the same genetic abnormalities, epigenetic defects, and microenvironmental aberrations cause different effects and lead to different outcomes in a progenitor stem cell versus a mature progeny cell. We need to recognize that an all-encompassing genetic theory of cancer may be incomplete and obsolete. A stem cell theory of cancer provides greater universality, interconnectivity, and utility. Although genetic defects are pivotal, cellular context is paramount. When it concerns tumor heterogeneity, perhaps we need to revisit the conventional wisdom of precision medicine and revise our current practice of targeted therapy in cancer care.

Curing Cancer: Lessons from a Prototype

Simple Summary

Germ cell tumor of the testis (TGCT) teaches us that to cure cancer, we need to acquire and apply proper biological insight and clinical acumen. In 1946, about 90% of patients with metastatic TGCT died within the first year of diagnosis. Today, over 90% of the same patients are curable. This complete reversal in the cure rate of TGCT is not because we have designed better drugs (we have not), but because we have learned how to use the same drugs in the right patients under the right settings. Importantly, TGCT is a prototype stem cell tumor that may hold the key to unlocking the origin of cancers, thereby enhancing our understanding of cancer and improving the cure and care of patients with cancer.

Abstract

Germ cell tumor of the testis (TGCT) is a remarkably curable solid tumor even when it is widely metastatic and patently heterogeneous. It provides invaluable clues about the origin and nature of metastasis and heterogeneity, cancer dormancy and late recurrence, drug sensitivity and resistance, tumor immunity, and spontaneous remission that would enable us to enhance the cure and improve the care of patients with other currently intractable solid tumors. After all, germ cells are primeval stem cells and TGCT are a perfect stem cell tumor for us to investigate a stem cell versus genetic origin of cancer. In many respects, TGCT is a prototype stem cell tumor that will enable us to elucidate the role of differentiation versus dedifferentiation in the evolution of a complex mixed tumor. It will help us decipher relevance of the genome versus the epi-genome in a progenitor cancer stem cell versus a progeny differentiated cancer cell. Importantly, clarification of a cellular context versus the genetic makeup in cancer has immense clinical implications. We postulate a unified theory of cancer derived from seminal TGCT research to improve personalized cancer care. Contrary to current norms and conventional wisdom, we propose that when it concerns a complex rather than simple cancer and a mixed rather than pure tumor (which is practically all solid tumors) multimodal therapy trumps targeted therapy and integrated medicine overrides precision medicine.

Application of a Successful Germ Cell Tumor Paradigm to the Challenges of Common Adult Solid Cancers

When we aspire to cure cancer, we may need to search no further than a curable cancer, such as Germ Cell Tumor of the Testis (TGCT). After all, a germ cell is a primordial stem cell. Importantly, TGCT provides a classic stem cell model of cancer that teaches us some invaluable lessons about curing other intractable solid tumors. The intrinsic intratumoral heterogeneity of TGCT alludes to its stem-ness origin and nature. Which implicates the existence of putative lethal TGCT subtypes-the identification and detection of which may further enhance the cure rate and improve the therapeutic ratio of TGCT. In this Mini review, we discuss about the role of biologic insights, clinical lessons, and therapeutic strategies in drug and therapy development. We illustrate some clinical pearls and perils when it concerns drug versus therapy development in the cure and care of patients with TGCT. In many respects, we have cured more TGCT patients when we apply multimodal therapy rather than targeted therapy and integrated medicine rather than precision medicine. In principle and in practice, this is the implication of therapy versus drug development in improving the overall outcome and cure rate of patients with cancer.

Origin of Subsequent Malignant Neoplasms in Patients with History of Testicular Germ Cell Tumor

Simple Summary

Although testicular germ cell tumor (TGCT) carries a high cure rate, some patients still die from it. We investigated the genetic landscape and cellular origins of cancers that develop later in life after treatment for TGCT and found evidence that a common progenitor cell might be responsible for both. This study shows the possible importance of stem-like cells in the development of cancer.

Abstract

Although genetic changes may be pivotal in the origin of cancer, cellular context is paramount. This is particularly relevant in a progenitor germ cell tumor and its differentiated mature teratoma counterpart when it concerns tumor heterogeneity and cancer dormancy in subsequent second malignancies (subsequent malignant neoplasms (SMNs)). From our tumor registry database, we identified 655 testicular germ cell tumor (TGCT) patients who developed SMNs between January 1990 and September 2018. Of the 113 solid organ SMNs, 42 had sufficient tumor tissue available for fluorescence in situ hybridization (FISH) analysis of isochromosome 12p [i(12p)]. We identified seven additional patients for targeted DNA and RNA sequencing of teratomas and adjacent somatic transformation. Finally, we established cell lines from freshly resected post-chemotherapy teratomas and evaluated the cells for stemness expression by flow cytometry and by the formation of teratomas in a xenograft model. In our cohort, SMNs comprising non-germ cell tumors occurred about 18 years after a diagnosis of TGCT. Of the 42 SMNs examined, 5 (12%) contained i(12p) and 16 (38%) had 12p gain. When comparing a teratoma and adjacent somatic transformation, targeted DNA and RNA sequencing demonstrated high concordance. Studies of post-chemotherapy teratoma-derived cell lines revealed cancer-initiating cells expressing multipotency as well as early differentiation markers. For the first time, we demonstrated the prevalence of i(12p) in SMNs and the presence of progenitor cells embedded within mature teratomas after chemotherapy. Our findings suggest a progenitor stem-like cell of origin in SMN and TGCT and highlight the importance of cellular context in this disease.

Establishment and characterisation of testicular cancer patient-derived xenograft models for preclinical evaluation of novel therapeutic strategies

Testicular cancer (TC) is the most common solid tumour in young men. While cisplatin-based chemotherapy is highly effective in TC patients, chemoresistance still accounts for 10% of disease-related deaths. Pre-clinical models that faithfully reflect patient tumours are needed to assist in target discovery and drug development. Tumour pieces from eight TC patients were subcutaneously implanted in NOD scid gamma (NSG) mice. Three patient-derived xenograft (PDX) models of TC, including one chemoresistant model, were established containing yolk sac tumour and teratoma components. PDX models and corresponding patient tumours were characterised by H&E, Ki-67 and cyclophilin A immunohistochemistry, showing retention of histological subtypes over several passages. Whole-exome sequencing, copy number variation analysis and RNA-sequencing was performed on these TP53 wild type PDX tumours to assess the effects of passaging, showing high concordance of molecular features between passages. Cisplatin sensitivity of PDX models corresponded with patients' response to cisplatin-based chemotherapy. MDM2 and mTORC1/2 targeted drugs showed efficacy in the cisplatin sensitive PDX models. In conclusion, we describe three PDX models faithfully reflecting chemosensitivity of TC patients. These models can be used for mechanistic studies and pre-clinical validation of novel therapeutic strategies in testicular cancer.

Paraneoplastic Limbic Encephalitis in a Patient with Primary Well-differentiated Teratoma and Metastatic Poorly Differentiated Embryonal Carcinoma

Testicular tumors account for 1-2% of all tumors in men, with 95% of these being germ cell tumors. Paraneoplastic limbic encephalitis is a rare sequela of testicular tumors associated with anti-Ma2 and KLH11 antibodies. The most effective treatment for paraneoplastic limbic encephalitis is treatment of the primary malignancy. We report a 41-year-old male that presented to the emergency department with episodic alteration of consciousness and memory disturbances. Negative neurologic evaluation and imaging led to concern for a paraneoplastic process from a distant malignancy. CT imaging revealed an enlarged, necrotic para-aortic lymph node and subsequent ultrasound demonstrated a right-sided testicular mass. Right radical orchiectomy was performed. Microscopically, the mass consisted of mixed respiratory epithelium, gastrointestinal glands, and squamous epithelium with keratinization consistent with a post-pubertal testicular teratoma with associated in situ germ cell neoplasia. Resection of the para-aortic mass revealed large anaplastic cells with epithelioid features, nuclear pleomorphism and frequent mitoses. Immunostaining was positive for Pan-Keratin and OCT4, consistent with poorly differentiated embryonal carcinoma. Resection of the primary and metastatic disease, as well as treatment with corticosteroids, resulted in resolution of the encephalitis. This presentation of severe neurological disturbances in the setting of a metastatic mixed non-seminomatous germ cell tumor represents a rare presentation of paraneoplastic limbic encephalitis.

Testicular cancer: Determinants of cisplatin sensitivity and novel therapeutic opportunities

Testicular cancer (TC) is the most common solid tumor among men aged between 15 and 40 years. TCs are highly aneuploid and the 12p isochromosome is the most frequent chromosomal abnormality. The mutation rate is of TC is low, with recurrent mutations in KIT and KRAS observed only at low frequency in seminomas. Overall cure rates are high, even in a metastatic setting, resulting from excellent cisplatin sensitivity of TCs. Factors contributing to the observed cisplatin sensitivity include defective DNA damage repair and a hypersensitive apoptotic response to DNA damage. Nonetheless, around 10-20% of TC patients with metastatic disease cannot be cured by cisplatin-based chemotherapy. Resistance mechanisms include downregulation of OCT4 and failure to induce PUMA and NOXA, elevated levels of MDM2, and hyperactivity of the PI3K/AKT/mTOR pathway. Several pre-clinical approaches have proven successful in overcoming cisplatin resistance, including specific targeting of PARP, MDM2 or AKT/mTOR combined with cisplatin. Finally, patient-derived xenograft models hold potential for mechanistic studies and pre-clinical validation of novel therapeutic strategies in TC. While clinical trials investigating targeted drugs have been disappointing, pre-clinical successes with chemotherapy and targeted drug combinations fuel the need for further investigation in clinical setting.

Prediction models for the viability of pulmonary metastatic lesions after chemotherapy in nonseminomatous germ cell tumors

OBJECTIVES

To analyze predictors associated with viable cells in pulmonary residual lesions after chemotherapy for metastatic testicular nonseminomatous germ cell tumors and to develop models to prioritize pulmonary resection.

METHODS

Between 2008 and 2017, 40 patients underwent pulmonary metastasectomy after chemotherapy for nonseminomatous germ cell tumors. We evaluated these patients, and 326 pulmonary residual lesions were confirmed using computed tomography and pathological evaluations. Relationships with outcomes were analyzed using logistic regression analyses. Risk prediction models were developed, and predictive probabilities for the risk of viable cells were estimated.

RESULTS

Histological examinations showed that 73 (22%) pulmonary residual lesions contained viable cells: teratomas, 46 (14%); and cancer cells, 37 (11%). Multivariate analyses showed that the predictors associated with cancer cells in the residual lesions were elevated tumor marker levels, multiregimen chemotherapy, increased tumor size 6 months before surgery and the histological composition of the primary lesion, including yolk sac tumors. Additional predictors associated with teratomas were aspect ratio and histological composition of the primary lesion, including teratomas.

CONCLUSIONS

Intratumoral heterogeneity contributes to nonseminomatous germ cell tumor chemoresistance, and primary lesion site yolk sac tumors and teratomas are associated with greater risks of viable cells. Increased residual lesion size during chemotherapy could also be a predictor. Our simple model can predict the presence of viable cells in residual lesions after chemotherapy, and it might assist in decision-making and prioritizing pulmonary residual lesion resection.

Systemic therapy for primary and extragonadal germ cell tumors: prognosis and nuances of treatment

Testicular germ cell tumors are the most common solid tumors in young men. These cancers represent a success story of modern medicine in our ability to cure young patients and offer decades of life, with a 5-year survival rate of approximately 95%. This review outlines the staging and risk classification of testicular cancers, and reviews the current state of knowledge and standard of care for the systemic treatment of testicular germ cell tumors with chemotherapy, focusing on the relevant clinical data supporting each treatment regimen. This review also briefly highlights current areas of active investigation, notably in the relapsed and refractory setting, including ongoing clinical trials.

Rapidly enlarging abdominal mass in a patient with recurrent germ cell tumor

This clinical image illustrates the alarming growth rate for an embryonal carcinoma, as well as its highly curable nature. For similar cases, early diagnosis and treatment are key.

Testicular germ cell tumor: a comprehensive review

Testicular tumors are the most common tumors in adolescent and young men and germ cell tumors (TGCTs) account for most of all testicular cancers. Increasing incidence of TGCTs among males provides strong motivation to understand its biological and genetic basis. Gains of chromosome arm 12p and aneuploidy are nearly universal in TGCTs, but TGCTs have low point mutation rate. It is thought that TGCTs develop from premalignant intratubular germ cell neoplasia that is believed to arise from the failure of normal maturation of gonocytes during fetal or postnatal development. Progression toward invasive TGCTs (seminoma and nonseminoma) then occurs after puberty. Both inherited genetic factors and environmental risk factors emerge as important contributors to TGCT susceptibility. Genome-wide association studies have so far identified more than 30 risk loci for TGCTs, suggesting that a polygenic model fits better with the genetic landscape of the disease. Despite high cure rates because of its particular sensitivity to platinum-based chemotherapy, exploration of mechanisms underlying the occurrence, progression, metastasis, recurrence, chemotherapeutic resistance, early diagnosis and optional clinical therapeutics without long-term side effects are urgently needed to reduce the cancer burden in this underserved age group. Herein, we present an up-to-date review on clinical challenges, origin and progression, risk factors, TGCT mouse models, serum diagnostic markers, resistance mechanisms, miRNA regulation, and database resources of TGCTs. We appeal that more attention should be paid to the basic research and clinical diagnosis and treatment of TGCTs.

Managing seminomatous and nonseminomatous germ cell tumors

PURPOSE OF REVIEW

In the present review, we summarize the recent developments in the management of germ cell tumors (GCTs).

RECENT FINDINGS

Treatment-related acute and late-onset toxicity remains a key challenge in the management of GCTs, with recent evidence showing that the adverse health outcomes of etoposide and cisplatin for four cycles in comparison to bleomycin, etoposide, and cisplatin for three cycles appear to be similar. Recent data showed that multidisciplinary clinic approach and management in experienced academic centers were associated with improved overall survival in GCT patients. There are currently multiple conventional-dose chemotherapy options for salvage therapy in patients with refractory or recurrent disease. In addition, more efficacious high-dose chemotherapy regimens continue to be developed. The role of salvage conventional-dose chemotherapy versus high-dose chemotherapy is currently being investigated prospectively. Recent reports suggested that brentuximab vedotin could be a potential salvage option for cluster of differentiation 30 positive refractory GCTs. On the other hand the results of the first phase II clinical trial investigating pembrolizumab in refractory GCTs were disappointing showing no clinical activity.Finally, deep exploration of the immune profile of GCTs using immunohistochemistry and gene expression profiling has identified that advanced GCT stage was associated with decreased T-cell and Natural killer-cell signatures, whereas T regulatory, neutrophil, mast cell, and macrophage signatures increased with advanced stage. Even though these results indicated that activated T-cell infiltration correlated with seminoma histology and good prognosis, and could be used in the future as a biomarker, this approach needs to be validated in a large cohort.

SUMMARY

Remaining challenges to be addressed include minimizing therapeutic toxicity, and improving outcomes in patients with refractory/recurrent GCTs.

Spontaneous regression as a 'burned-out' non-seminomatous testicular germ cell tumor: a case report and literature review

Testicular germ cell tumors (TGCTs) are the most frequent type of cancer in young adults. An exceptional event is the spontaneous regression (SR) of the primary tumor. Herein, we describe a burned-out non-seminomatous TGCT case and relevant literature review. A 34-year-old male presenting with low back pain was found to have a retroperitoneal mass upon urotomography. During workup, a heterogeneous testicular mass was evident, and its biopsy showed findings that support the diagnosis of spontaneous tumoral regression. The patient underwent unilateral orchiectomy and a chemotherapy protocol was later initiated, with 85% regression of the retroperitoneal metastatic mass. No progression of the primary tumor has been found. The etiology of SR across different cancer types appears to be associated with the host's immune response and an angiogenic disturbance of the tumor microenvironment. The burned-out phenomenon is a rare event that needs further research into its molecular sequencing.

Role of HNF1β in the differential diagnosis of yolk sac tumor from other germ cell tumors

Identification of the yolk sac tumor (YST) component in germ cell tumors (GCT) may prove challenging, and highly sensitive and specific immunohistochemical markers are still lacking. Preliminary data from the literature suggest that HNF1β may represent a sensitive marker of YST. The specificity of HNF1β has not been addressed in GCT. A cohort of 49 YST specimens from 45 patients was designed, occurring either as pure tumors, or as a component of a mixed GCT. Immunohistochemistry was conducted on whole tumor sections using HNF1β. SALL4, OCT4, CD30, CDX2, Cytokeratin 19, Glypican 3, and GATA3 were used for classification of the GCT components. Patients were mostly male (39/45), aged 14 months to 49 years, with primary testicular tumors (37/39), or primary mediastinal pure YSTs (2/39). All 6 primary tumors occurring in females (6/45) were pure ovarian YSTs; age range was 4 to 72 years. HNF1β nuclear reactivity was seen in the YST component in all 49 tumors, with a moderate to strong nuclear pattern of staining. Embryonal carcinoma (EC, 0/32) and seminoma (0/6) were negative. Choriocarcinoma (6/6) showed faint focal cytoplasmic reactivity to HNF1β but no nuclear staining. In teratomas, only enteric-type glands showed nuclear reactivity to HNF1β (11/16). Therefore, HNF1β sensitivity in YST component identification was 100% and specificity was 80%. Thus, in our experience, HNF1β is a sensitive and reliable marker of the YST component in GCT, and allows distinction of YST from intricately admixed EC, especially in the diffuse embryoma pattern.

SOX2 is essential for in vivo reprogramming of seminoma-like TCam-2 cells to an embryonal carcinoma-like fate

Type II germ cell cancers (GCC) are divided into seminomas, which are highly similar to primordial germ cells and embryonal carcinomas (EC), often described as malignant counterparts to embryonic stem cells.

Previously, we demonstrated that the development of GCCs is a highly plastic process and strongly influenced by the microenvironment. While orthotopic transplantation into the testis promotes seminomatous growth of the seminoma-like cell line TCam-2, ectopic xenotransplantation into the flank initiates reprogramming into an EC-like fate.

During this reprogramming, BMP signaling is inhibited, leading to induction of NODAL signaling, upregulation of pluripotency factors and downregulation of seminoma markers, like SOX17. The pluripotency factor and EC-marker SOX2 is strongly induced.

Here, we adressed the molecular role of SOX2 in this reprogramming. Using CRISPR/Cas9-mediated genome-editing, we established SOX2-deficient TCam-2 cells. Xenografting of SOX2-deficient cells into the flank of nude mice resulted in maintenance of a seminoma-like fate, indicated by the histology and expression of OCT3/4, SOX17, TFAP2C, PRDM1 and PRAME. In SOX2-deficient cells, BMP signaling is inhibited, but NODAL signaling is not activated. Thus, SOX2 appears to be downstream of BMP signaling but upstream of NODAL activation. So, SOX2 is an essential factor in acquiring an EC-like cell fate from seminomas.

A small population of differentiated cells was identified resembling a mixed non-seminoma. Analyses of these cells revealed downregulation of the pluripotency and seminoma markers OCT3/4, SOX17, PRDM1 and TFAP2C. In contrast, the pioneer factor FOXA2 and its target genes were upregulated, suggesting that FOXA2 might play an important role in induction of non-seminomatous differentiation.

Detailed pathologic analysis on the co-occurrence of non-seminomatous germ cell tumor subtypes in matched orchiectomy and retroperitoneal lymph node dissections

The frequency of co-occurrence between germ cell tumor (GCT) components in non-seminomatous germ cell tumor (NSGCT) orchiectomy specimens and their correlation with histologic findings in subsequent retroperitoneal lymph node dissection (RPLND) specimens have not been well characterized. The objective of the study was to report the first detailed clinicopathologic analysis of NSGCT orchiectomy and RPLND samples to determine the likelihood and agreement of the co-occurrence of GCT components. A total of 118 consecutive patients with NSGCT treated between 1988 and 2012 who underwent both orchiectomy and RPLND at a single academic tertiary care center were analyzed. Statistical analysis of co-occurrence likelihood and agreement of GCT components was performed, both within and between orchiectomy and RPLND specimens. Embryonal carcinoma was the most frequent component present in orchiectomy specimens, and there were multiple significant associations between orchiectomy GCT components; seminoma occurred less frequently with embryonal carcinoma (OR 0.29 [95% confidence interval (CI) 0.11-0.75]; p < 0.01), and teratoma more frequently occurred with choriocarcinoma (OR 9.64 [95% CI 1.22-76.12]; p = 0.01). Presence of teratoma in the orchiectomy specimen predicted for a fourfold increase in distant metastasis on multivariate analysis (HR 4.92 [1.14-18.9]; p = 0.02). The only significant association of co-occurrence in the RPLND specimen was between embryonal carcinoma and teratoma (OR 0.01 [95% CI 0-0.07]; p < 0.001), where it was significantly less likely for them to occur together. Our findings are limited by their retrospective nature. The co-occurrence of GCT components within orchiectomy specimens does not appear to be a completely random process. However, there is less agreement and more randomness between the occurrence of the GCT components in matched orchiectomy and RPLND samples. In this report, we look at the co-occurrence of different GCT components within matched orchiectomy and RPLND pathology specimens and show that co-occurrence is not a completely random process.

Recent developments in the management of germ cell tumors

PURPOSE OF REVIEW

In the present review, we summarize the recent developments in the management of germ cell tumors (GCTs).

RECENT FINDINGS

Treatment-related acute and late-onset toxicity remains a key challenge in the management of GCTs. Recent data show that patients with large retroperitoneal lymph node metastases are at increased risk of venous thromboembolism and may benefit from prophylactic anticoagulation. Predictive models have been developed to identify patients with residual retroperitoneal lymph node masses who are more likely to benefit from surgical resection. However, their clinical use remains hampered by relatively low accuracy. There are currently multiple conventional-dose chemotherapy (CDCT) options for salvage therapy in patients with refractory or recurrent disease. In addition, more efficacious high-dose chemotherapy (HDCT) regimens continue to be developed. The role of salvage CDCT versus HDCT is currently being prospectively investigated.Finally, intratumoral heterogeneity is a common finding in cancer and an obvious observation in GCTs. Despite intratumoral heterogeneity, recent studies on nonseminomatous GCT have identified distinct histological subgroups and a potentially lethal clinical phenotype. Importantly, comprehensive molecular profiling so far has not elucidated the biologic basis or the clinical underpinnings of intratumoral heterogeneity in GCTs.

SUMMARY

Remaining challenges to be addressed include minimizing therapeutic toxicity and improving outcomes in patients with refractory/recurrent GCTs or malignant transformation of teratomas.

Testicular germ cell tumor genomics

PURPOSE OF REVIEW

Testicular germ cell tumors (TGCTs) are a model for curable cancer because of exquisite chemosensitivity and incorporation of multimodal therapy. Nevertheless, our ability to predict metastases in early-stage disease and responders to chemotherapy in advanced disease is limited. Treatment options for cisplatin-resistant disease are sparse. A further understanding of TGCT biology may allow for more precise patient counseling and identify novel therapies in patients with cisplatin-resistant disease.

RECENT FINDINGS

Adult TGCTs are characterized by frequent chromosomal anomalies and low rates of somatic mutations. Large-scale integrated molecular analysis of early-stage TGCT patients is actively underway. In addition to ubiquitous gain of isochromosome 12p, current molecular studies have confirmed mutations of previously described genes (i.e., KIT and KRAS) and described novel mutations. Analysis of cisplatin-resistant cases has identified high rates of alterations within the TP53-MDM2 axis and a high proportion of patients with potentially actionable targets, including TP53-MDM2, PI3 kinase, and MAPK signaling pathway alterations. The role of epigenetics in TGCT development and prognosis is also being further characterized.

SUMMARY

Further molecular characterization of TGCT may allow for avoidance of unnecessary treatment in patients with early-stage disease and also provide new treatment options in patients with cisplatin-resistant disease.

Intratumoral heterogeneity and chemoresistance in nonseminomatous germ cell tumor of the testis

BACKGROUND

Nonseminomatous germ cell tumor of the testis (NSGCT) is largely curable. However, a small group of patients develop refractory disease. We investigated the hypothesis that intratumoral heterogeneity contributes to the emergence of chemoresistance and the development of refractory tumor subtypes.

RESULTS

Our institution's records for January 2000 through December 2010 included 275 patients whose primary tumor showed pure embryonal carcinoma (pure E); mixed embryonal carcinoma, yolk sac tumor, and teratoma (EYT); or mixed embryonal carcinoma, yolk sac tumor, seminoma, and teratoma (EYST). Patients with EYST had the highest cancer-specific mortality rate (P = .001). They tended to undergo somatic transformation (P = .0007). Two of 5 patients with clinical stage I EYST who had developed recurrence during active surveillance died of their disease.

MATERIALS AND METHODS

In this retrospective study, we evaluated consecutive patients who had been diagnosed with the three most common histological phenotypes of NSGCT. Chemoresistance was defined as the presence of teratoma, viable germ cell tumor, or somatic transformation in the residual tumor or the development of progressive or relapsed disease after chemotherapy. In a separate prospective study, we performed next-generation sequencing on tumor samples from 39 patients to identify any actionable genetic mutations.

CONCLUSIONS

Our data suggest that patients with EYST in their primary tumor may harbor a potentially refractory NSGCT phenotype and are at increased risk of dying from disease. Despite intratumoral heterogeneity, improved patient selection and personalized care of distinct tumor subtypes may optimize the clinical outcome of patients with NSGCT.