New target therapies in prostate cancer: from radioligand therapy, to PARP-inhibitors and immunotherapy.

Prostate cancer (PCa) remains a significant global health challenge, particularly in its advanced stages. Despite progress in early detection and treatment, PCa is the second most common cancer diagnosis among men. This review aims to provide an overview of current therapeutic approaches and innovations in PCa management, focusing on the latest advancements and ongoing challenges. We conducted a narrative review of clinical trials and research studies, focusing on PARP inhibitors (PARPis), phosphoinositide 3 kinase-protein kinase B inhibitors, immunotherapy, and radioligand therapies (RLTs). Data was sourced from major clinical trial databases and peer-reviewed journals. Androgen deprivation therapy and androgen-receptor pathway inhibitors remain foundational in managing castration-sensitive and early-stage castration-resistant PCa (CRPC). PARPi's, such as olaparib and rucaparib, have emerged as vital treatments for metastatic CRPC with homologous recombination repair gene mutations, highlighting the importance of personalized medicine. Immune checkpoint inhibitors (ICIs) have shown clinical benefit limited to specific subgroups of PCa, demonstrating significant improvement in efficacy in patients with microsatellite instability/mismatch repair or cyclin-dependent kinase 12 alteration, highlighting the importance of focusing ongoing research on identifying and characterizing these subgroups to maximize the clinical benefits of ICIs. RLTs have shown effectiveness in treating mCRPC. Different alpha emitters (like [225Ac]PSMA) and beta emitters compounds (like [177Lu]PSMA) impact treatment differently due to their energy transfer characteristics. Clinical trials like VISION and TheraP have demonstrated positive outcomes with RLT, particularly [177Lu]PSMA-617, leading to FDA approval. Ongoing trials and future perspectives explore the potential of [225Ac]PSMA, aiming to improve outcomes for patients with mCRPC. The landscape of PCa treatment is evolving, with significant advancements in both established and novel therapies. The combination of hormonal therapies, chemotherapy, PARPis, immunotherapy, and RLTs, guided by genetic and molecular insights, opens new possibilities for personalized treatment.

Target Therapy in Malignant Pleural Mesothelioma: Hope or Mirage?

Malignant Pleural Mesothelioma (MPM) is a rare neoplasm that is typically diagnosed in a locally advanced stage, making it not eligible for radical surgery and requiring systemic treatment. Chemotherapy with platinum compounds and pemetrexed has been the only approved standard of care for approximately 20 years, without any relevant therapeutic advance until the introduction of immune checkpoint inhibitors. Nevertheless, the prognosis remains poor, with an average survival of only 18 months. Thanks to a better understanding of the molecular mechanisms underlying tumor biology, targeted therapy has become an essential therapeutic option in several solid malignancies. Unfortunately, most of the clinical trials evaluating potentially targeted drugs for MPM have failed. This review aims to present the main findings of the most promising targeted therapies in MPM, and to explore possible reasons leading to treatments failures. The ultimate goal is to determine whether there is still a place for continued preclinical/clinical research in this area.

Management of Germ Cell Tumors During the Outbreak of the Novel Coronavirus Disease-19 Pandemic: A Survey of International Expertise Centers.

BACKGROUND: The coronavirus disease 2019 (COVID-19) pandemic has become a public health emergency affecting frail populations, including patients with cancer. This poses the question of whether cancer treatments can be postponed or modified without compromising their efficacy, especially for highly curable cancers such as germ cell tumors (GCTs). MATERIALS AND METHODS: To depict the state-of-the-art management of GCTs during the COVID-19 pandemic, a survey including 26 questions was circulated by e-mail among the physicians belonging to three cooperative groups: (a) Italian Germ Cell Cancer Group; (b) European Reference Network-Rare Adult Solid Cancers, Domain G3 (rare male genitourinary cancers); and (c) Genitourinary Medical Oncologists of Canada. Percentages of agreement between Italian respondents (I) versus Canadian respondents (C), I versus European respondents (E), and E versus C were compared by using Fisher's exact tests for dichotomous answers and chi square test for trends for the questions with three or more options. RESULTS: Fifty-three GCT experts responded to the survey: 20 Italian, 6 in other European countries, and 27 from Canada. Telemedicine was broadly used; there was high consensus to interrupt chemotherapy in COVID-19-positive patients (I = 75%, C = 55%, and E = 83.3%) and for use of granulocyte colony-stimulating factor primary prophylaxis for neutropenia (I = 65%, C = 62.9%, and E = 50%). The main differences emerged regarding the management of stage I and stage IIA disease, likely because of cultural and geographical differences. CONCLUSION: Our study highlights the common efforts of GCT experts in Europe and Canada to maintain high standards of treatment for patients with GCT with few changes in their management during the COVID-19 pandemic. IMPLICATIONS FOR PRACTICE: Despite the chaos, disruptions, and fears fomented by the COVID-19 illness, oncology care teams in Italy, other European countries, and Canada are delivering the enormous promise of curative management strategies for patients with testicular cancer and other germ cell tumors. At the same time, these teams are applying safe and innovative solutions and sharing best practices to minimize frequency and intensity of patient contacts with thinly stretched health care capacity.

Clinical outcomes in octogenarians treated with docetaxel as first-line chemotherapy for castration-resistant prostate cancer.

AIM: To assess clinical outcomes in octogenarians treated with docetaxel (DOC) for metastatic castration-resistant prostate cancer. PATIENTS & METHODS: The multicenter retrospective study was based on a review of the pre- and post-DOC clinical history, DOC treatment and outcomes. RESULTS: We reviewed the records of 123 patients (median age: 82 years) who received DOC every 3 weeks or weekly, without significant grade 3-4 toxicities. Median progression-free survival was 7 months; median overall survival from the start of DOC was 20 months, but post-progression treatments significantly prolonged overall survival. CONCLUSION: The findings of this study suggest that toxicity is acceptable, survival is independent of patient's age and survival can be significantly prolonged by the use of new agents.

Targeted therapy for thymic epithelial tumors: a new horizon? Review of the literature and two cases reports.

Surgical resection remains the cornerstone of therapy for early-stage thymic epithelial tumors (TETs), while in advanced or recurrent forms, a multimodality approach incorporating radiation and chemotherapy is required. Given the absence of effective treatment options for metastatic/refractory TETs and the poor related prognosis, there is a compelling need to identify promising 'drugable' molecular targets. Initial reports of activity from targeted agents in TETs derived from anecdotal cases have been often associated with specific activating mutations. Only in recent years, several agents have been formally investigated into prospective clinical trials, with varying success rates. We reviewed the literature on targeted therapy in TETs along with two cases of thymoma achieving striking responses to sorafenib in combination with lapatinib.

Geographical differences in the management of metastatic de novo renal cell carcinoma in the era of immune-combinations.

BACKGROUND: The upfront treatment of metastatic renal cell carcinoma (mRCC) has been revolutionized by the introduction of immune-based combinations. The role of cytoreductive nephrectomy (CN) in these patients is still debated. The ARON-1 study (NCT05287464) was designed to globally analyze real-world data of mRCC patients receiving first-line immuno-oncology combinations. This sub-analysis is focused on the role of upfront or delayed partial or radical CN in three geographical areas (Western Europe, Eastern Europe, America/Asia). METHODS: We conducted a multicenter retrospective observational study in mRCC patients treated with first-line immune combinations from 55 centers in 19 countries. From 1152 patients in the ARON-1 dataset, we selected 651 patients with de novo mRCC. 255 patients (39%) had undergone CN, partial in 14% and radical in 86% of cases; 396 patients (61%) received first-line immune-combinations without previous nephrectomy. RESULTS: Median overall survival (OS) from the diagnosis of de novo mRCC was 41.6 months and not reached (NR) in the CN subgroup and 24.0 months in the no CN subgroup, respectively (P<0.001). Median OS from the start of first-line therapy was NR in patients who underwent CN and 22.4 months in the no CN subgroup (P<0.001). Patients who underwent CN reported longer OS compared to no CN in all the three geographical areas. CONCLUSIONS: No significant differences in terms of patients' outcome seem to clearly emerge, even if the rate CN and the choice of the type of first-line immune-based combination varies across the different Cancer Centers participating in the ARON-1 project.

Tumor treating fields affect mesothelioma cell proliferation by exerting histotype-dependent cell cycle checkpoint activations and transcriptional modulations.

Although clinical antitumor activity of Tumor Treating Fields (TTFields) has been reported in malignant pleural mesothelioma (MPM) patients, the mechanisms behind the different selectivity displayed by the various MPM histotypes to this physical therapy has not been elucidated yet. Taking advantage of the development of well characterized human MPM cell lines derived from pleural effusion and/or lavages of patients' thoracic cavity, we investigated the biological effects of TTFields against these cells, representative of epithelioid, biphasic, and sarcomatoid histotypes. Growth inhibition and cell cycle perturbations caused by TTFields were investigated side by side with RNA-Seq analyses at different exposure times to identify pathways involved in cell response to treatment. We observed significant differences of response to TTFields among the cell lines. Cell cycle analysis revealed that the most sensitive cells (epithelioid CD473) were blocked in G2M phase followed by formation of polyploid cells. The least sensitive cells (sarcomatoid CD60) were only slightly affected by TTFields with a general delay in all cell cycle phases. Apoptosis was present in all samples, but while epithelioid cell death was already observed during the first 24 h of treatment, sarcomatoid cells needed longer times before they engaged apoptotic pathways. RNA-Seq experiments demonstrated that TTFields induced a transcriptional response already detectable at early time points (8 h). The number of differentially expressed genes was higher in CD473 than in CD60 cells, involving several pathways, such as those pertinent to cell cycle checkpoints, DNA repair, and histone modifications. Our data provide further support to the notion that the antitumor effects of TTFields are not simply related to a non-specific reaction to a physical stimulus, but are dependent on the biological background of the cells and the particular sensitivity to TTFields observed in epithelioid MPM cells is associated with a higher transcriptional activity than that observed in sarcomatoid models.

SARS-CoV-2 vaccine in patients with thymic epithelial tumours with and without active or pre-existing autoimmune disorders: Brief report of a TYME network safety analysis.

BACKGROUND: International guidelines recommend severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccine for patients with cancer. A substantial risk of developing vaccine-related autoimmune toxicities could be hypothesised for patients with thymic epithelial tumours (TETs) due to their high risk of autoimmune disorders (ADs). Moreover, a cross-reaction between SARS-CoV-2 spike protein antibodies and various tissue proteins has been shown, and antibodies against nucleoproteins showed overlaps in the autoimmune cross-reaction with antibodies to spike protein. Due to the rarity of TETs, no data addressing this hypothesis are available. METHODS: Patients with TETs who received SARS-CoV-2 vaccine, treated in 4 referral centres of the Italian Collaborative Group for ThYmic MalignanciEs (TYME) network between February 2021 and September 2021, were interviewed through a standardised 15-items questionnaire in order to describe the safety of SARS-CoV-2 vaccine in patients affected by TETs. RESULTS: Data from 245 doses of vaccine administered to 126 patients (41 = thymic carcinoma, 85 = thymoma; 38 with AD, of which 26 with active AD) were collected. Nine patients had a previous COVID-19-positive swab. No cases of AD reactivation or worsening of a pre-existing AD were seen in the study population. A new diagnosis of myasthenia gravis likely unrelated to the vaccine was made in two patients after the vaccination. Sixty-four patients (51%) experienced a total of 103 adverse events, all G1/G2, most commonly fatigue, new or worsening muscle pain and chills. None AE required patients' hospitalisation. CONCLUSIONS: SARS-CoV-2 mRNA vaccines appear to be safe in patients with TET, even in case of active or pre-existing AD.

Bladder metastases of appendiceal mucinous adenocarcinoma: a case presentation.

BACKGROUND: Appendiceal adenocarcinoma is rare with a frequency of 0.08% of all surgically removed appendices. Few cases of appendiceal carcinoma infiltrating the bladder wall for spatial contiguity have been documented. CASE PRESENTATION: A case is reported of a 45-years old woman with mucinous cystadenocarcinoma of the appendix with bladder metastasis. Although ultrasonography and voided urinary cytology were negative, abdomen computed tomography (CT) scan and cystoscopy and subsequent pathological examination revealed a mass exclusively located in the anterior wall of the bladder. Histopathology of the transurethral bladder resection revealed a bladder adenocarcinoma [6 cm (at the maximum diameter) x 2,5 cm; approximate weight: 10 gr] with focal mucinous aspects penetrating the muscle and perivisceral fat. Laparotomy evidenced the presence of a solid mass of the appendix (2,5 cm x 3 cm x 2 cm) extending to the loco-regional lymph nodes. Appendectomy and right hemicolectomy, linfoadenectomy and partial cystectomy were performed. The subsequent pathological examination revealed a mucinous cystadenocarcinoma of the appendix with metastatic cells colonising the anterior bladder wall and several colic lymph nodes. CONCLUSIONS: The rarity of the appendiceal carcinoma invading the urinary bladder and its usual involvement of nearest organs and the posterior bladder wall, led us to describe this case which demonstrates the ability of the appendiceal cancer to metastasize different regions of urinary bladder.

Morphometric vertebral fractures in patients with castration-resistant prostate cancer undergoing treatment with radium-223: a longitudinal study in the real-life clinical practice.

PURPOSE: Radium-223 was associated with high incidence of non-vertebral fractures in patients with castration-resistant prostate cancer (CRPC). However, it is still unclear whether radium-223 may induce skeletal fragility regardless of other therapies for CRPC. We aimed at evaluating the prevalence, incidence, and determinants of vertebral fractures (VFs), i.e., the most frequent complication of skeletal fragility, in CRCP patients undergoing radium-223 therapy in the real-life clinical practice. METHODS: We retrospectively reviewed 49 CRPC patients with symptomatic bone metastases treated with radium-223. Patients received median number of four radium-223 doses (range: 2-6) and were followed-up for a median period of 11 months (range: 6-44). VFs were assessed by a quantitative morphometry using lateral images of spine 11C-Choline PET/CT, excluding from the analysis the vertebral bodies affected by bone metastases. RESULTS: Before radium-223 administration, 24 patients (49%) had VFs significantly associated with duration of androgen deprivation therapy (ADT; odds ratio 1.29) and previous abiraterone therapy (odds ratio 3.80). During radium-223 therapy, incident VFs occurred in 25% of patients, in relationship with prevalent VFs (hazard ratio 6.89) and change in serum total alkaline phosphatase values (hazard ratio 0.97), whereas the correlations with ADT and abiraterone therapy were lost. Noteworthy, the risk of VFs did not correlate with the therapeutic end points of radium-223. CONCLUSIONS: This study provides a first evidence that in real-life clinical practice, radium-223 therapy may induce skeletal fragility with high risk of VFs, likely by inhibition of bone formation and independently of ADT and abiraterone therapy.

Gene methylation in pleural mesothelioma: correlations with clinico-pathological features and patient's follow-up.

Methylation of tumor suppressor genes is among the most frequent alterations in patients with malignant pleural mesothelioma (MPM). The aim of this study was to analyze the promoter methylation status of four tumor suppressor genes, p15(INK4B), p16(INK4A), RASSF1A and NORE1A in MPM. Samples of 79 MPM patients were analyzed using a methylation-specific PCR method. Associations between methylation status, clinico-pathological parameters (including proliferation index) and overall survival (OS) were examined. The analysis documented methylation in 30 cases (38%). The methylation frequency for individual genes was 19% for p15(INK4B) (n=15), 11.4% for p16(INK4A) (n=9), 20.2% for RASSF1A (n=16) and 5.1% for Nore1A (n=4). In the whole series methylation was associated to an increased proliferation index (P=0.05). In patients treated with extrapleural pneumonectomy, methylated MPM showed a trend to a poorer OS in comparison to unmethylated cases (median OS 16 months vs. 35 months, P=0.06, HR=2.01, 95% CI 0.95-4.30). In the overall population, methylation did not correlate to patient outcome but a trend to an improved survival was detectable in ummethylated MPM treated with extrapleural pneumonectomy. This result suggests the need to select homogeneously treated and staged patients with MPM to address whether their methylation profile may impact on patient's survival.

Target therapy: new drugs or new combinations of drugs in malignant pleural mesothelioma.

Malignant pleural mesothelioma (MPM) is a disease with a poor prognosis due to its aggressive nature. The management of patients with MPM is controversial. Considering that the contribution of surgery and radiation therapy in the management of this disease is not yet established, systemic treatments are predominantly considered during the course of MPM. Unfortunately, the currently therapeutic armamentarium is scarce and its outcomes still appear modest. New treatment strategies are needed. In preclinical setting, cell cycle regulation, apoptosis, growth factor pathways, and angiogenesis pathways involved in the development of MPM have been identified. However, in clinical setting, several drugs targeting these pathways resulted without a significant activity. A deeper knowledge of the biology and pathogenesis of this disease is required to develop more effective tools for diagnosis, therapy and prevention. This paper reviews therapeutic advances in MPM, with a particular focus on new drugs and new association of drugs of target therapy.

Assessment of tumor response in malignant pleural mesothelioma.

Most patients with malignant pleural mesothelioma (MPM) are candidates for chemotherapy during the course of their disease. Assessment of the response with conventional criteria based on computed tomography (CT) measurements is challenging, due to the circumferential and axial pattern of growth of MPM. Such difficulties hinder an accurate evaluation of clinical study results and make the clinical management of patients critical. Several radiological response systems have been proposed, but neither WHO criteria nor the more recent RECIST unidimensional criteria nor hybrid uni- and bidimensional criteria seem to apply to tumor measurement in this disease. Recently, modified RECIST criteria for MPM have been published. Although they are already being used in current clinical trials, they have been criticized based on the high grade of inter-observer variability and on theoretical studies of mesothelioma growth according to non-spherical models. Computer-assisted techniques for CT measurement are being developed. The use of FDG-PET for prediction of response and, more importantly, of survival outcomes of MPM patients is promising and warrants validation in large prospective series. New serum markers such as osteopontin and mesothelin-related proteins are under evaluation and in the future might play a role in assessing the response of MPM to treatment.

Biology and management of malignant pleural mesothelioma.

Malignant mesothelioma is an aggressive tumour, with a poor prognosis and an increasing incidence as a result of widespread exposure to asbestos. The results of the treatments available are poor. Surgery and radiotherapy have a limited role in highly selected patients and systemic therapy is the only potential treatment option for the majority of patients. Despite some definite activity of the novel antifolates such as pemetrexed and raltitrexed, the results, even in combination with platinating agents, are still modest, with a median survival of approximately one year. The better understanding of the biology of mesothelioma makes the assessment of a number of targeted agents particularly interesting. Unfortunately, the targeted agents imatinib, gefitinib, erlotinib and thalidomide have been shown to be ineffective in unselected patients. Studies with anti-angiogenesis agents are ongoing. An improvement of the knowledge of major molecular pathways involved in malignant mesothelioma is needed in order to define proper targets for the systemic treatment of this disease.

A specific inhibitor of lactate dehydrogenase overcame the resistance toward gemcitabine in hypoxic mesothelioma cells, and modulated the expression of the human equilibrative transporter-1.

Malignant pleural mesothelioma (MPM) is a very hypoxic malignancy, and hypoxia has been associated with resistance towards gemcitabine. The muscle-isoform of lactate dehydrogenase (LDH-A) constitutes a major checkpoint for the switch to anaerobic glycolysis. Therefore we investigated the combination of a new LDH-A inhibitor (NHI-1) with gemcitabine in MPM cell lines. Under hypoxia (O2 tension of 1%) the cell growth inhibitory effects of gemcitabine, were reduced, as demonstrated by a 5- to 10-fold increase in IC50s. However, the simultaneous addition of NHI-1 was synergistic (combination index < 1). Flow cytometry demonstrated that hypoxia caused a G1 arrest, whereas the combination of NHI-1 significantly increased gemcitabine-induced cell death. Finally, the mRNA expression levels of the human equilibrative transporter-1 (hENT1) were significantly down-regulated under hypoxia, but treatment with NHI-1 was associated with a recovery of hENT1 expression. In conclusion, our data show that hypoxia increased MPM resistance to gemcitabine. However, cell death induction and modulation of the key transporter in gemcitabine uptake may contribute to the synergistic interaction of gemcitabine with the LDH-A inhibitor NHI-1 and support further studies for the rational development of this combination.

A specific missense mutation in GTF2I occurs at high frequency in thymic epithelial tumors.

We analyzed 28 thymic epithelial tumors (TETs) using next-generation sequencing and identified a missense mutation (chromosome 7 c.74146970T>A) in GTF2I at high frequency in type A thymomas, a relatively indolent subtype. In a series of 274 TETs, we detected the GTF2I mutation in 82% of type A and 74% of type AB thymomas but rarely in the aggressive subtypes, where recurrent mutations of known cancer genes have been identified. Therefore, GTF2I mutation correlated with better survival. GTF2I ß and δ isoforms were expressed in TETs, and both mutant isoforms were able to stimulate cell proliferation in vitro. Thymic carcinomas carried a higher number of mutations than thymomas (average of 43.5 and 18.4, respectively). Notably, we identified recurrent mutations of known cancer genes, including TP53, CYLD, CDKN2A, BAP1 and PBRM1, in thymic carcinomas. These findings will complement the diagnostic assessment of these tumors and also facilitate development of a molecular classification and assessment of prognosis and treatment strategies.

Copy number aberrations of genes regulating normal thymus development in thymic epithelial tumors.

PURPOSES: To determine whether the deregulation of genes relevant for normal thymus development can contribute to the biology of thymic epithelial tumors (TET). EXPERIMENTAL DESIGN: Using array comparative genomic hybridization, we evaluated the copy number aberrations of genes regulating thymus development. The expression of genes most commonly involved in copy number aberrations was evaluated by immunohistochemistry and correlated with patients' outcome. Correlation between FOXC1 copy number loss and gene expression was determined in a confirmation cohort. Cell lines were used to test the role of FOXC1 in tumors. RESULTS: Among 31 thymus development-related genes, PBX1 copy number gain and FOXC1 copy number loss were presented in 43.0% and 39.5% of the tumors, respectively. Immunohistochemistry on a series of 132 TETs, including those evaluated by comparative genomic hybridization, revealed a correlation between protein expression and copy number status only for FOXC1 but not for PBX1. Patients with FOXC1-negative tumors had a shorter time to progression and a trend for a shorter disease-related survival. The correlation between FOXC1 copy number loss and mRNA expression was confirmed in a separate cohort of 27 TETs. Ectopic FOXC1 expression attenuated anchorage-independent cell growth and cell migration in vitro. CONCLUSION: Our data support a tumor suppressor role of FOXC1 in TETs.

Phase I pharmacokinetic and pharmacodynamic study of lapatinib in combination with sorafenib in patients with advanced refractory solid tumors.

BACKGROUND: The epidermal growth factor receptor (EGFR) and ERBB2 (HER2) pathways and vascular endothelial growth factor (VEGF)-dependent angiogenesis have a pivotal role in cancer pathogenesis and progression. Robust experimental evidence has shown that these pathways are functionally linked and implicated in acquired resistance to targeted therapies making them attractive candidates for joined targeting. We undertook this phase I trial to assess the safety, the recommended dose for phase II trials (RPTD), pharmacokinetics (PK), pharmacodynamics (PD), and the preliminary antitumour activity of the combination of lapatinib and sorafenib in patients with advanced refractory solid tumours. METHODS: Four cohorts of at least three patients each received lapatinib once daily and sorafenib twice daily together on a continuous schedule. Doses of lapatinib and sorafenib were escalated based on dose-limiting toxicities (DLTs) in the first treatment cycle following a traditional 3+3 design until the RPTD was reached. Additional patients were treated at the RPTD to characterise PK profiles of this combination and to investigate the potential interaction between lapatinib and sorafenib. Serum samples were collected at baseline and then prospectively every two cycles to assess changes in PD parameters. This trial is registered with ClinicalTrials.gov, number NCT00984425. FINDINGS: Thirty patients with advanced refractory solid tumours were enroled. DLTs were grade three fatigue and grade 3 atypical skin rash observed at dose levels 3 and 4, respectively. The higher dose level explored (lapatinib 1250mg/day and sorafenib 400mg twice daily) represented the RPTD of the combination. The most common drug-related adverse events were fatigue (68%), hypocalcemia (61%), diarrhoea (57%), lymphopaenia (54%), anorexia (50%), rash (50%), and hypophosphatemia (46%). PK analysis revealed no significant effect of sorafenib on the PK profile of lapatinib. Of the 27 assessable patients for clinical activity, one achieved a confirmed complete response, four (15%) had a partial response, and 12 (44%) achieved disease stabilisation. The disease control rate overall was 63%. INTERPRETATION: Combination treatment with lapatinib and sorafenib was feasible with promising clinical activity and without significant PK interactions. Long term tolerability seems to be challenging.

NUT rearrangement is uncommon in human thymic epithelial tumors.

INTRODUCTION: Thymic carcinomas represent the most aggressive histotype of thymic epithelial tumors (TETs). The 2004 World Health Organization classification has assigned a subgroup of thymic carcinomas as t(15;19) carcinomas based on the presence of t(15;19), a translocation found in poorly differentiated and highly aggressive NUT midline carcinomas. These tumors are characterized byrearrangement of the NUT (nuclear protein in testis) gene on chromosome 15q14, which in most cases fuses to the bromodomain containing 4 (BRD4) gene on chromosome 19 p13.1 through reciprocal t(15;19) translocation, resulting in constitutive BRD4-NUTfusion protein expression. To our knowledge, NUT translocation has been reported only in four thymic carcinomas. Due to the rarity of TETs, the prevalence of NUT rearrangement in TETs has however never been systematically explored. METHODS: Formalin-fixed paraffin-embedded samples of histologically confirmed TETs were evaluated for NUT expression and rearrangement by immunohistochemistry and fluorescence in situ hybridization, respectively. RESULTS: A series of 148 TETs (37 carcinomas and 111 thymomas) were examined for NUT expression and rearrangement. Only one thymic carcinoma (2.7% of thymic carcinomas or 0.68% of TETs) was found positive for NUT expression and rearrangement. CONCLUSIONS: Rearrangement of NUT is infrequent in TETs. We propose that caution should be taken to distinguish t(15;19) thymic carcinoma from other mediastinal carcinomas, as NUT midline carcinomas are often associated with dreadful prognosis or overt lethality.