Premature Classification of Early-stage Endometrioid Ovarian Carcinoma With Mesonephric-like Differentiation as Mesonephric-like Adenocarcinoma.

Ovarian mesonephric-like adenocarcinoma (MLA) is a rare tumor with potential origins in endometriosis and Müllerian-type epithelial tumors. The morphologic patterns of MLA overlap with those of endometrioid ovarian carcinoma (EnOC). We speculated that a subset of MLAs would be classified as EnOCs. In this study, we attempted to identify MLAs from malignant endometrioid tumors. Given that the study patients with MLAs had both endometrioid-like and mesonephric-like morphologies, we defined mesonephric-like differentiation (MLD) as an endometrioid tumor with focal or diffuse MLA morphology and immunophenotype. Twelve patients exhibited mesonephric-like morphologic patterns. Immunohistochemistry analysis for CD10, TTF-1, estrogen receptor (ER), GATA3, calretinin, and PAX8 expression was done using whole-section slides. Two patients without the MLA immunophenotype were excluded. Ten patients with EnOCs with MLD (8.3%) were identified from a cohort of 121 patients with malignant endometrioid tumors. All 10 patients were positive for TTF-1 and/or GATA3. Most patients were ER-negative. Morphologically, MLD was associated with papillary thyroid carcinoma-like nuclei, flattened cells, tubular, nested, reticular, or glomeruloid architecture, and infiltrative growth. All 10 patients had pre-existing endometriosis and/or adenofibromas. Among the EnOCs with MLD, 5 had coexisting components such as EnOC grade 1 [(G1), cases 4, 7, and 9], mucinous borderline tumor (case 1), and dedifferentiated carcinoma (case 10), with distinct borders between EnOC with MLD and the other components. Nine of the 10 MLA patients (90%) harbored KRAS hotspot mutations. In addition, 4 patients harboring other components shared common KRAS hotspot mutations. No significant prognostic differences were observed between patients with and without MLD. Based on our findings, we suggest that EnOC with MLD, especially in the early stages and without high-grade components, should be considered a subtype of EnOC. Overtreatment should be avoided in such patients, particularly in the early stages. In this study, as the characteristics between EnOC with MLD and MLA were not distinguishable, we considered both conditions to be on the same spectrum. EnOCs with MLD exhibit the MLA phenotype during disease progression and are prematurely classified as MLA. Nevertheless, more patients with EnOC who have MLD/MLA are required for a more robust comparison between conventional EnOC according to staging and grading.

Carcinoma showing thymus-like elements (CASTLE) with amyloid deposition in the parotid gland.

Carcinoma showing thymus-like elements (CASTLE) is a rare tumor that commonly occurs in the thyroid gland. Extrathyroidal CASTLE is rarer, and only 11 cases of CASTLE of major salivary glands have been reported to date. We report the first case of amyloid deposition in parotid CASTLE. A 63-year-old man presented with a slowly growing mass in the left parotid region. Computed tomography revealed an approximately 28 × 23 mm mass lesion in the left parotid gland, and squamous cell carcinoma was suspected on biopsy. The patient underwent a parotidectomy with neck dissection. Morphologically, the tumor cells were squamoid and formed nests with lymphoid infiltration. Immunohistochemically, the tumor cells exhibited immunoreactivity for CD5, CD117/c-kit and Bcl-2, p40, and CK5 but not for p16. We diagnosed the tumor as parotid CASTLE. Amyloid deposition was also observed in the primary tumor and metastatic lymph node lesions, which were immunoreactive for cytokeratin 5. Tumor cytokeratin-derived amyloid deposition may be one of characteristics of parotid CASTLE.

An autopsy case of prostatic rhabdomyosarcoma with DICER1 hotspot mutation.

Somatic hotspot DICER1 mutations, which frequently coexist with germline inactivating mutation (i.e., DICER1 syndrome), have been identified in various types of benign and malignant conditions. Herein, we report an autopsy case of prostatic rhabdomyosarcoma (RMS) with a hotspot DICER1 c.5125G>A (p.D1709N) mutation. A 26 year-old man presented with a prostatic mass, hematuria, and urinary retention. He underwent total pelvic exenteration, colostomy, ileal conduit construction and partial urethrectomy. Five months postoperatively, he developed multiple metastases to the lungs, brain, iliopsoas muscles and bones. He died of respiratory failure, and autopsy was performed. Microscopically, the tumor was primarily composed of uniform primitive mesenchymal cells infiltrating to the prostate with cambium layer. Rhabdomyoblasts and anaplastic cells were focally observed. Immunohistochemically, tumor cells were positive for desmin, myogenin, PAX7, HMGA2. Multinodular goiter was detected at autopsy. Because the morphology is similar to pleuropulmonary blastoma and DICER1-mutant RMS of the female genital tract, we tested and identified a hotspot DICER1 mutation with Sanger sequencing. Recognizing DICER1-mutant tumor is important because of its frequent association with germline DICER1 inactivation and potential therapeutic implication. Further research is needed to clarify whether this case can be classified as embryonal RMS with anaplasia or 'DICER1-associated sarcoma'.

Fluorescence Detection of Prostate Cancer by an Activatable Fluorescence Probe for PSMA Carboxypeptidase Activity.

Prostate cancer (PCa) is a common malignant tumor among adult males, and convenient intraoperative detection of PCa would reduce the risk of leaving positive surgical margins, especially during nerve-sparing procedures. To achieve rapid, fluorescence-based visualization of PCa, we focused on the glutamate carboxypeptidase (CP) activity of prostate-specific membrane antigen (PSMA), a type II transmembrane glycoprotein that is attracting attention as a PCa biomarker. Based on our finding that aryl glutamate conjugates with an azoformyl linker are recognized by PSMA and have a sufficiently low LUMO (lowest unoccupied molecular orbital) energy level to quench the fluorophore through photoinduced electron transfer, we designed and synthesized a first-in-class activatable fluorescence probe for CP activity of PSMA. The developed probe allowed us to visualize the CP activity of PSMA in living cells and in clinical specimens from PCa patients and is expected to be useful for rapid intraoperative detection and diagnosis of PCa.

Clinicopathological characteristics of patients with upper urinary tract urothelial cancer with loss of immunohistochemical expression of the DNA mismatch repair proteins in universal screening.

OBJECTIVES: To assess the detection rate of putative Lynch syndrome-associated upper urinary tract urothelial cancer among all upper urinary tract urothelial cancers and to examine its clinicopathological characteristics. METHODS: A total of 143 patients with upper urinary tract urothelial cancer who had received total nephroureterectomy were immunohistochemically stained for the expression of mismatch repair proteins MLH1, PMS2, MSH2 and MSH6. For all suspected mismatch repair-deficient cases, MMR genetic testing was recommended and clinicopathological features were examined. RESULTS: Loss of mismatch repair proteins was found in seven patients (5%) who were thus categorized as putative Lynch syndrome-associated upper urinary tract urothelial cancer. Five of these patients showed dual loss of MSH2/MSH6. Two patients were confirmed to be MSH2 germline mutation carriers. Histologically, all seven tumors were low-grade atypical urothelial carcinoma and showed its unique histological features, such as an inverted papilloma-like growth pattern and a villous to papillary structure with mild stratification of tumor cells. Six tumors had no invasion of the muscularis propria. No recurrence or cancer-related deaths were reported in these seven patients. Just three patients met the revised Amsterdam criteria. CONCLUSIONS: This is the first report that universally examined mismatch repair immunohistochemical screening for upper urinary tract urothelial cancers. The prevalence (5%) of putative Lynch syndrome-associated upper urinary tract urothelial cancers is much higher than we had expected. We ascertained that putative Lynch syndrome-associated upper urinary tract urothelial cancers were clinically in the early stage and histologically classified into low-grade malignancy with its characteristic pathological features. The clinicopathological characteristics that we found in the present study could become additional possible markers in the diagnosis of Lynch syndrome-associated upper urinary tract urothelial cancers.

Prognostic value of programmed death-ligand 1 expression in patients with stage III colorectal cancer.

The programmed death-1/programmed death-ligand 1 (PD-L1) pathway is a negative feedback pathway that suppresses the activity of T cells. Previous studies reported that high PD-L1 expression on tumor cells (TC) was associated with poor survival in patients with colorectal cancer; however, the prognostic evaluation of these studies was limited because they included patients at various disease stages. The purpose of the present study was to evaluate the relationship between PD-L1 status in the immune microenvironment and the clinicopathological features of stage III colorectal cancer. Two hundred and thirty-five patients were included in the analysis. PD-L1 expression on TC and tumor-infiltrating mononuclear cells (TIMC) was evaluated by immunohistochemistry. The median follow-up of thisi study was 52.9 months. A total of 8.1% of stage III colorectal cancer showed high PD-L1 expression on TC and 15.3% showed high PD-L1 expression on TIMC. Patients with high PD-L1 expression on TC had significantly shorter disease-free survival (DFS) than patients with low expression (hazard ratio [HR] 2.36; 95% confidence interval [CI], 1.21-4.62; P = 0.012). In addition, patients with high PD-L1 expression on TIMC were associated with longer DFS than patients with low expression (HR 0.40; 95% CI, 0.16-0.98; P = 0.046). These findings suggest that PD-L1 expression status may be a new predictor of recurrence for stage III colorectal cancer patients and highlight the necessity of evaluating PD-L1 expression on TC and TIMC separately in the tumor microenvironment.

Loss of Stromal Antigen 2 (STAG2) Expression in Upper Urinary Tract Carcinoma: Differential Prognostic Effect According to the Ki-67 Proliferating Index.

BACKGROUND: Inactivating mutation and consequent expression loss of stromal antigen 2 (STAG2, also known as SA2), a component of the cohesion complex, is one of the most common genetic aberrations in urothelial carcinoma. However, the clinicopathologic or prognostic significance of STAG2 alterations in upper tract urothelial carcinoma (UTUC) is largely unknown. METHODS: This study immunohistochemically examined the expression of STAG2 in 171 patients with UTUC. The correlations of STAG2 loss with clinicopathologic features and patients' prognoses were examined. RESULTS: Loss of STAG2 expression was observed in 28 cases (16%). Loss of STAG2 was significantly correlated with histological low grade, papillary architecture, noninvasive tumors, absence of concomitant carcinoma in situ, and lower Ki-67 expression. Loss of STAG2 alone was not significantly associated with patients' prognoses in either the uni- or multivariate analysis. However, STAG2 loss was significantly associated with worse clinical outcome in UTUC with high Ki-67 proliferation indexes, but not in UTUC with low Ki-67 expression. CONCLUSIONS: Loss of STAG2 was generally associated with less aggressive features in UTUC. However, the STAG2 loss was an ominous sign in the subpopulation with higher Ki-67 proliferation indexes. Examining both STAG2 and Ki-67 status may be useful for identifying aggressive clinical behavior of UTUC.

Cervical lymphoepithelioma-like carcinoma with deficient mismatch repair and loss of SMARCA4/BRG1: a case report and five related cases.

BACKGROUND: We encountered a cervical lymphoepithelial carcinoma (LEC) possessing a predominantly solid architecture with deficient mismatch repair (dMMR) and loss of expression of the SWI/SNF (SWItch/Sucrose Non-Fermentable) chromatin remodeling complex subunit. This is the first case report of LEC with dMMR and loss of SWI/SNF complex subunit. CASE PRESENTATION: A 34-year-old woman presented at our hospital with menstrual irregularities and abnormal vaginal bleeding. Magnetic resonance imaging revealed an exophytic mass in the posterior uterine cervix. Biopsy specimens confirmed squamous cell carcinoma with a 2018 International Federation of Gynecology and Obstetrics (FIGO) uterine cervical cancer stage of IB2. In a subsequent conization specimen, the tumor appeared exophytic. Microscopically, the tumor cells formed a predominant solid architecture. Abundant lymphocytic infiltration was observed. The pathological diagnosis indicated human papillomavirus (HPV)-associated squamous cell carcinoma with LEC pattern and pT1b2. Immunohistochemically, high programmed death-ligand 1 (PD-L1) expression, dMMR, and loss of the switch/sucrose non-fermentable family-related, matrix-associated, actin-dependent regulator of chromatin subfamily member 4 (SMARCA4)/BRG1, an SWI/SNF complex subunit, were observed. The patient underwent a radical hysterectomy and is alive without disease one year and five months later. Our analysis of five additional LEC cases revealed a consistent association with high-risk HPV and elevated PD-L1 expression. In addition to the present case, another patient exhibited dMMR. The SWI/SNF complex was retained except in the present case. The prognosis was favorable in all cases. CONCLUSIONS: This unique case of LEC with dMMR suggests a distinct clinical entity with potential immunotherapy implications. Analysis of the other five LEC cases revealed that LEC was immune hot, and immune checkpoint inhibitors may be effective. The two dMMR cases showed loss of MLH1 and PMS2 expressions, and prominently high tumor PD-L1 expression. In those cases, dMMR might have contributed to the morphological characteristics of LEC.

Aggressive variant prostate cancer with multiple subcutaneous metastases: a case report.

A 71-year-old man with bone metastasis of hormone-sensitive prostate cancer was treated with androgen deprivation therapy and apalutamide. Radium-223 and radiation therapy were administered after it become castration resistant. Although prostate-specific antigen levels remained low, multiple subcutaneous metastases of neuroendocrine prostate cancer were observed. A review of the pre-treatment prostate needle biopsy revealed a small component with features suggestive of neuroendocrine differentiation. Phosphatase and tensine homolog loss and tumor protein p53 overexpression were observed, confirming the diagnosis of aggressive variant prostate cancer. Platinum-based chemotherapy was administered; however, the patient died 28 months after diagnosis. In this case, if the diagnosis of aggressive variant prostate cancer had been made at an earlier time by biopsy specimens, there might have been a possibility to improve the prognosis by the earlier introduction of the platinum-based regimen. Supplementary Information: The online version contains supplementary material available at 10.1007/s13691-024-00673-7.

Acute subdural hematoma caused by hemorrhagic falx meningioma: A case report and review of the literature.

We herein report a case of acute subdural hematoma caused by hemorrhagic falx meningioma. The patient was a 64-year-old woman with no significant medical history or prior history of trauma. She experienced a sudden onset of headache and weakness in her extremities. Computed tomography (CT) scan and magnetic resonance imaging (MRI) showed a mass lesion with intratumoral hemorrhage or faint calcification along the left side of the fronto-parietal cerebral falx. There was also a linear lesion at the left side of the falx, suggesting acute subdural hematoma. MRI was performed again on the eleventh day. On precontrast T1-weighted images, intratumoral hemorrhage and widespread left subdural hematoma were shown as high intensity. On postcontrast T1-weighted images, the tumor showed heterogeneous enhancement with a dural tail sign on the falx, indicative of a falx meningioma. She underwent surgical resection, and the histological subtype was transitional meningioma. Nine cases of hemorrhagic falx meningioma associated with acute subdural hematoma have been reported. If not limited to the site of occurrence, there have been 59 reported cases overall. In our investigation, the incidence of hemorrhage is higher in the convexity and lower in the skull base. It is higher for fibrous, angiomatous, and metaplastic subtypes and lower for meningothelial subtype. The location and histological subtype might be risk factors for meningioma associated with subdural hematoma. Further accumulation of cases will be necessary to establish the cause of bleeding.

Concordance Between Biopsy and Resection Diagnoses of Uterine Cervical Adenocarcinoma According to the Updated World Health Organization 2020 Classification: A Multi-Institutional Study Elucidating Real-World Practice in Japan.

CONTEXT.­: Endocervical adenocarcinoma is divided into human papillomavirus (HPV)-associated (HPVA) and HPV-independent (HPVI) in the 5h edition of the World Health Organization (WHO) tumor classification launched in 2020. However, the validity of the morphological criteria used for biopsy specimens in real-world practice remains undetermined. OBJECTIVE.­: To validate the utility of the 5th edition of the WHO classification for biopsy samples, focusing on its diagnostic criteria with the aid of ancillary studies. DESIGN.­: We retrieved 217 cases of endocervical adenocarcinoma from 6 institutions, in which glass slides of both biopsy and resection specimens were available for review. Concordance between the biopsy and resection specimen diagnoses was evaluated. For discordant diagnoses, an algorithmic approach with ancillary studies proposed by the international group was applied to confirm their utility to improve the accuracy of biopsy diagnosis. RESULTS.­: The biopsy diagnosis matched the resection specimen diagnosis in 197 cases (concordance rate, 91%; κ = 0.75). The concordance rate was significantly higher for HPVA than HPVI (95% versus 81%, P = .001). There were no significant differences in the proportions of HPVA and HPVI or the accuracy of biopsy diagnosis between the participating institutions. All 19 discordant cases with unstained glass slides available were accurately recategorized as HPVA or HPVI using HPV in situ hybridization; p16 immunohistochemistry was positive in 3 of 9 cases of gastric-type HPVI that were negative by in situ hybridization. CONCLUSIONS.­: The 5th edition of the WHO criteria for biopsy diagnosis of endocervical adenocarcinoma distinguishes HPVA from HPVI well when ancillary studies are adequately applied.

Robot-Assisted Partial Cystectomy Using the "Double Bipolar Method".

The "double bipolar method" (DBM) in robotic surgery has been widely used in Japanese general surgery and gynecology; however, it is not commonly used in the field of urology. A 55-year-old female was diagnosed with stage IA endometrial cancer. A 2-cm cystic lesion was incidentally observed at the dome of the bladder on magnetic resonance imaging. A simultaneous robot-assisted total hysterectomy and partial cystectomy using the da Vinci Xi system was planned. The gynecological procedure was first performed with the DBM, and the DBM was also used in the partial cystectomy without additional instruments to reduce surgical costs. Maryland bipolar forceps was used to excise the peritoneum, fat, and bladder wall without bleeding, enabling delicate and precise resection using the forceps' tips. Robot-assisted partial cystectomy using the DBM was feasible. When performing combined surgeries with other departments, if the DBM is already being utilized, it is worthwhile to attempt to decrease surgical cost.

Choroidal Metastasis From Papillary Renal Cell Carcinomas: A Case Report and a Review of the Literature.

Choroidal metastasis originating from renal cell carcinomas (RCCs) is rare. To the best of our knowledge, 31 cases of choroidal metastasis from RCC have been reported in the English literature as of January 31, 2024. Nevertheless, physicians need to be vigilant in recognizing this condition, as its progression impacts the quality of life (QOL) of affected patients. In Case 1, a 60-year-old male with a medical history of papillary RCC experienced a deterioration in visual acuity (VA) and was diagnosed with solitary choroidal metastasis. Subsequently, multiple metastases were identified, prompting the initiation of a combination therapy regimen consisting of pembrolizumab plus axitinib. Despite treatment, progression of choroidal metastasis and a further decline in VA were observed. The patient underwent stereotactic radiotherapy and experienced complete resolution of the choroidal metastasis, accompanied by a slight improvement in VA. In Case 2, a 76-year-old man presented with a renal tumor accompanied by lung metastases. He underwent nephrectomy, and the histological diagnosis was papillary RCC. We initiated combination therapy consisting of nivolumab plus cabozantinib. The patient experienced a decrease in VA during treatment. We identified extensive fine metastases scattered throughout the bilateral choroid. We administered axitinib, but the patient experienced bilateral blindness. Given the absence of established therapy for choroidal metastasis, it is crucial to maintain flexibility in treatment selection. Local or systemic approaches should be used as deemed appropriate for each individual case.

Complete response to pembrolizumab in a patient with recurrent and metastatic urothelial bladder carcinoma reflecting coexisting sarcomatoid subtype and glandular differentiation: a case report.

In advanced urothelial carcinoma (UC), approximately 20% of patients respond to pembrolizumab, an anti-programmed cell death-1 (PD-1) antibody. Herein, we reported a single case of UC showing coexistence of sarcomatoid subtype and glandular differentiation. Notably, only glandular differentiation was recurrent, probably progressive, and metastatic, which showed complete response to pembrolizumab. An 80-year-old woman presented with hematuria and dysuria, and an intra-vesical tumor was detected on ultrasound. Transurethral resections (TUR) were performed three times. In the first TUR, a sub-pedunculated tumor and a flat lesion were closely but independently located. Pathologically, the sub-pedunculated tumor was an invasive UC, sarcomatoid subtype. Meanwhile, the flat lesion was invasive UC with glandular differentiation. Despite the second and the additional TUR, the tumor was growing and a lymph node metastasis was detected. The third TUR specimen showed UC with glandular differentiation, and a positive PD-L1 expression as well as high density CD8-positive lymphocytic cells infiltration were observed. Pembrolizumab was administered for four courses after terminating the chemotherapy. The CT scan revealed shrinkage of both primary tumor and metastases. Cystectomy and lymph nodes dissection were performed, and no residual carcinoma was detected. The therapeutic effect was regarded as pathological complete response. Pembrolizumab could be effective for special subtype or divergent differentiation of UC, particularly in an event of an 'immune hot' tumor. Supplementary Information: The online version contains supplementary material available at 10.1007/s13691-022-00568-5.

Inter- and intra-tumor heterogeneity of genetic and immune profiles in inherited renal cell carcinoma.

Patients with von Hippel-Lindau disease (vHL) are at risk of developing spatially and temporally multiple clear cell renal cell carcinomas (ccRCCs), which offers a valuable opportunity to analyze inter- and intra-tumor heterogeneity of genetic and immune profiles within the same patient. Here, we perform whole-exome and RNA sequencing, digital gene expression, and immunohistochemical analyses for 81 samples from 51 ccRCCs of 10 patients with vHL. Inherited ccRCCs are clonally independent and have less genomic alterations than sporadic ccRCCs. Hierarchical clustering of transcriptome profiles shows two clusters with distinct immune signatures: immune hot and cold clusters. Interestingly, not only samples from the same tumors but also different tumors from the same patients tend to show a similar immune signature, whereas samples from different patients frequently exhibit different signatures. Our findings reveal the genetic and immune landscape of inherited ccRCCs, demonstrating the relevance of host factors in shaping anti-tumor immunity.

Lower neutrophil-to-lymphocyte ratio and positive programmed cell death ligand-1 expression are favorable prognostic markers in patients treated with pembrolizumab for urothelial carcinoma.

BACKGROUND: Immune checkpoint inhibitors (ICIs) are effective in some cancer patients; however, they may show no efficacy in others. Predictive biomarkers are crucial for appropriately selecting the patients who receive ICI therapy. This study aimed to clarify the predictors of disease progression in urothelial carcinoma (UC) patients treated with an ICI, pembrolizumab. METHODS: We analyzed the response patterns of 50 UC patients who were treated with pembrolizumab, as well as the association between survival and clinicopathological factors. Clinical factors included age, sex, body mass index, clinical courses, laboratory data, metastases, and adverse events. Pathological factors included special variant, squamous differentiation, programmed cell death ligand-1 (PD-L1) expression, CD8-positive lymphocytes density, and CDKN2A/p16 homozygous deletion. RESULTS: During pembrolizumab treatment, four (8%), 11 (22%), and eight (16%) patients achieved the best-case scenarios of complete response, partial response, and stable disease, respectively. Twenty-seven patients (54%) showed progressive disease. In this study, younger age, lower preoperative neutrophil-to-lymphocyte ratio (NLR), and positive PD-L1 expression were significantly correlated with longer progression-free survival and overall survival. Moreover, lower NLR and positive PD-L1 expression were independently associated with longer OS in multivariate analysis. CONCLUSIONS: Based on our observations, lower NLR and positive PD-L1 expression may be independent favorable prognostic markers in UC patients treated with pembrolizumab. These results suggest that both host and tumor status can reflect the effectiveness of pembrolizumab among patients with UC.

An Autopsy Case of Late-onset Fulminant Myocarditis Induced by Nivolumab in Gastric Cancer.

Nivolumab is an immune-checkpoint inhibitor (ICI) that can induce unique treatment-related toxicities, such as immune-related adverse events (irAEs). Myocarditis is a serious irAE with an incidence between 0.06% and 1.14%. Although the peak onset of irAE is generally within three months from the start of treatment, we experienced an autopsy case of late-onset fulminant myocarditis caused by nivolumab in Epstein Barr virus-associated gastric cancer. Pathological complete remission of the primary lesion was confirmed by the autopsy. We should consider possible complications of cardiac irAEs, especially fulminant myocarditis, even beyond three months after starting ICI therapy.

Case Study: A Japanese patient with metastatic renal cell carcinoma who achieved long-term treatment-free survival with pembrolizumab and axitinib in the KEYNOTE-426 phase III trial of pembrolizumab and axitinib versus sunitinib.

Introduction: Our patient treated with pembrolizumab and axitinib is one of the longest survivors in Japan on KEYNOTE 426, despite adverse events, including delayed-onset hepatitis. We herein present a detailed clinical course and short discussion on the case. Case presentation: This was a 49-year-old male with clear cell renal cell carcinoma and lung metastases. After cytoreductive nephrectomy, treatment with pembrolizumab plus axitinib was initiated and the patient demonstrated a radiographic partial response as best response. The main adverse event was pembrolizumab-induced delayed-onset hepatitis, which was successfully treated with prednisolone. Pembrolizumab was re-initiated and completed. Conclusion: The survival benefit in the present case may be due to the initial potent anti-cancer effects of axitinib and durable immune effects of pembrolizumab, leading to long-term treatment-free survival.

Squamous differentiation is a potential biomarker predicting tumor progression in patients treated with pembrolizumab for urothelial carcinoma.

Immune checkpoint inhibitor (ICI) is widely used and highly effective for some cancer patients but may result in disease progression in others. Hyperprogressive disease in particular is characterized by an acceleration of tumor growth during ICI therapy and has been reported in patients including those with urothelial carcinoma. Biomarkers predicting treatment efficacy are crucial to avoid tumor progression and unnecessary adverse effects. This study aims to clarify the predictors of disease progression for ICI treatment in patients with urothelial carcinoma. We analyzed the response pattern of 23 urothelial carcinomas treated with pembrolizumab and its association with pathological features and potential immunohistochemical markers including EGFR, MDM2, p53, p16, and programmed cell death ligand-1 (PD-L1) expression and CD8- and CD204-positive cell infiltration. During ICI therapy, 13 (57 %) patients showed progressive disease including 6 (26 %) with hyperprogressive disease. Notably, squamous differentiation combined with MAC387 expression was observed exclusively in cases with progressive disease (6 of 13, 46 %); it was not present in cases with stable disease or partial/complete response (0 of 10, p = 0.0019). All tumors with squamous differentiation showed positive staining for EGFR. Additionally, the loss of p16 expression occurred more frequently in cases with progressive disease (8 of 13, 62 %) than in other cases (3 of 10, 30 %), but this finding did not reach statistical significance. Squamous differentiation was also significantly associated with shorter overall survival. Based on our observations, squamous differentiation may be a novel biomarker for predicting disease progression in patients with urothelial carcinoma who receive pembrolizumab.