Negative Staining Research Articles

Primary spinal cord gliomas: Pathologic features associated with prognosis.

Primary spinal cord gliomas are rare and are associated with high mortality. Unlike brain tumors, the clinicopathological features of spinal cord gliomas are not well defined. We analyzed clinical, histopathology, and immunohistochemical features and overall survival (OS) of 25 patients with primary spinal cord gliomas treated between 1994 and 2023 at 4 institutions. IDH1 R132H, H3K27M, and p53 were assessed by immunohistochemistry (IHC). Four (16%), 5 (20%), 2 (8%), and 13 (52%) patients were diagnosed as having grades 1, 2, 3, and 4 gliomas according to the World Health Organization (WHO) 2021 classification, respectively. One case (4%), with a circumscribed diffuse midline glioma, H3K27-altered, had a rare molecular profile and could not be graded. IHC demonstrated H3K27M positivity, indicative of H3F3A K27M or HIST1H3B K27M mutation, in 9 (36%) patients. H3K27me3-loss was evident in 13 (52%) patients. In one patient with a grade 1 tumor that showed negative staining for H3K27M and H3K27me3 loss, numbers of EZHIP-positive cells were increased, suggesting diffuse midline glioma, H3K27-altered (WHO grade 4). H3K27me3 loss, frequency of p53 positive cells (≥10%), MIB-1 index (≥10%), and high histopathological grades significantly correlated with poor OS. These results indicate the pathological and immunohistochemical characteristics of primary spinal cord gliomas that impact prognosis.

Swinepox virus: an unusual outbreak in free-range pig farms in Sicily (Italy)

BackgroundTwo outbreaks of swinepox were investigated in free-range domestic pig farms located in the northeastern side of Sicily, Italy. The disease is generally self-limiting with a low mortality rate, but morbidity can reach high rates in case of poor sanitary conditions, improper husbandry practices and ectoparasitic infestation. The presented cases are the first ever reported on the island and part of the few cases reported in domestic pigs.Case presentationCarcasses condemned at the slaughterhouse and deceased pigs from Farm A and Farm B respectively, were referred for post-mortem examination and further investigations, with a strong suspect of SwinePox virus (SWPV) infection. Twelve deceased pigs were examined in total, showing poor body condition and pustular lesions scattered all over the cutaneous surfaces. Moreover, pigs from Farm B showed ocular lesions classified from Grade I to IV (from mild conjunctivitis to severe keratoconjunctivitis with corneal oedema, opacity, and ulcers). Final diagnosis was pursued by the microscopic assessment of skin lesions in both farms, which revealed the typical SWPV-lesion appearance, such as severe and disseminated ulcerative dermatitis and suspected inclusion bodies multifocally observed in the epidermis. Moreover, negative staining Electron Microscopy (nsEM) was performed on skin lesions and ocular swabs from Farm B, revealing in two samples the presence of brick-shaped viral particles, 220 nm long and 160 nm wide, with irregularly arranged surface tubules, identified as SWPV. The gene encoding the 482-bp fragment of the virus late transcription factor–3 was detected by PCR and sequencing revealed 99.79% identity and 100% query-cover with a strain previously isolated in Germany. Field clinical assessment was then performed in Farm B, revealing high overcrowding, poor sanitary conditions and improper husbandry practices, which are relevant risk factors for SWPV transmission.ConclusionsThe present is the first case report of SWPV in free-range pigs raised in Sicily, an island of the Southern coast of Italy, and wants to raise awareness on a neglected disease, and cause of animal health and welfare issues.

Utility of C4d Immunohistochemistry in the Diagnosis of Esophageal Pemphigus Vulgaris.

Aims. To assess the utility of C4d immunohistochemistry for esophageal pemphigus vulgaris. Methods and results. We searched for patients with a history of esophageal pemphigus vulgaris who had esophageal biopsies for routine hematoxylin and eosin (H&E) staining. A total of 8 biopsies from 7 patients were available. We also identified 18 non-pemphigus esophageal biopsies for controls. C4d immunohistochemistry was performed on each biopsy. Five of 6 (83%) biopsies with classic pemphigus vulgaris histologic findings were positive for intercellular staining at the basal layer. The negative biopsy was in a patient that had recently received high-dose corticosteroid treatment for a flare. Two biopsies with atypical histologic features for pemphigus vulgaris had negative C4d staining but positive direct immunofluorescence (DIF) studies. Various nonspecific C4d staining patterns were observed in the controls, but none showed the intercellular staining pattern that was observed in pemphigus vulgaris. Conclusions. Suprabasal clefting with acantholysis and "tombstone effect" are described histologic features of pemphigus vulgaris on H&E. However, procedural artifact may mimic these findings. Currently, the gold standard for pemphigus vulgaris is DIF, which is not always available because it cannot routinely be performed on formalin-fixed paraffin embedded tissue. Our study shows that C4d immunohistochemistry may be a useful adjunct in evaluating esophageal pemphigus vulgaris.

Succinate dehydrogenase A deficient renal cell carcinoma: A rare renal tumor distinct from typical Succinate dehydrogenase deficient renal cell carcinoma

Succinate dehydrogenase (SDH)-deficient renal cell carcinoma (RCC) is a rare subtype of RCC classified as a molecularly defined RCC in the fifth edition of the WHO. Most gene alterations in patients with SDH-deficient RCC involve the SDHB subunit, with less involvement of the SDHC, SDHA, and SDHD subunits. Four cases of SDHA-deficient RCC have been reported in the literature, of which one case was associated with an NF2 gene mutation. Herein, we report six novel SDHA-deficient RCC cases, including two cases with NF2 gene mutations. In contrast to the typical morphology of SDH-deficient RCC, the six tumors mainly displayed glandular, sheet-like, or papillary growth patterns with prominent nucleoli (Grades 2–3), among which two cases with NF2 mutations had prominent nucleoli (Grade 3), large transparent vacuoles in the cytoplasm, and a large number of lymphocytes in the stroma. Six tumors showed negative immunohistochemical staining for SDHA and SDHB, and three cases presented with high expression of PD-L1. Second-generation sequencing revealed novel pathogenic somatic SDHA gene mutation and NF2 gene mutations in six and two tumors, respectively. Follow-up data were collected for the six patients with a follow-up time ranging from 7 to 268 months, and all six patients have survived to date. One patient received targeted therapy for tumor metastasis to the lungs after seven months, and another patient with an NF2 gene mutation received immunotherapy for lymph node metastasis revealed during surgery. SDHA-deficient RCCs with NF2 gene mutations have the ability to metastasize but might respond well to immunotherapy. For the first time, we report the largest number of SDHA-deficient RCC cases and comprehensively investigate their clinicopathological and molecular features to provide important guidance for diagnosis and clinical immunotherapy.

In vitro higher-order oligomeric assembly of the respiratory syncytial virus M2-1 protein with longer RNAs.

The respiratory syncytial virus (RSV) M2-1 protein is a transcriptional antitermination factor crucial for efficiently synthesizing multiple full-length viral mRNAs. During RSV infection, M2-1 exists in a complex with mRNA within cytoplasmic compartments called inclusion body-associated granules (IBAGs). Prior studies showed that M2-1 can bind along the entire length of viral mRNAs instead of just gene-end (GE) sequences, suggesting that M2-1 has more sophisticated RNA recognition and binding characteristics. Here, we analyzed the higher oligomeric complexes formed by M2-1 and RNAs in vitro using size exclusion chromatography (SEC), electrophoretic mobility shift assays (EMSA), negative stain electron microscopy (EM), and mutagenesis. We observed that the minimal RNA length for such higher oligomeric assembly is about 14 nucleotides for polyadenine sequences, and longer RNAs exhibit distinct RNA-induced binding modality to M2-1, leading to enhanced particle formation frequency and particle homogeneity as the local RNA concentration increases. We showed that particular cysteine residues of the M2-1 cysteine-cysteine-cystine-histidine (CCCH) zinc-binding motif are essential for higher oligomeric assembly. Furthermore, complexes assembled with long polyadenine sequences remain unaffected when co-incubated with ribonucleases or a zinc chelation agent. Our study provided new insights into the higher oligomeric assembly of M2-1 with longer RNA.IMPORTANCERespiratory syncytial virus (RSV) causes significant respiratory infections in infants, the elderly, and immunocompromised individuals. The virus forms specialized compartments to produce genetic material, with the M2-1 protein playing a pivotal role. M2-1 acts as an anti-terminator in viral transcription, ensuring the creation of complete viral mRNA and associating with both viral and cellular mRNA. Our research focuses on understanding M2-1's function in viral mRNA synthesis by modeling interactions in a controlled environment. This approach is crucial due to the challenges of studying these compartments in vivo. Reconstructing the system in vitro uncovers structural and biochemical aspects and reveals the potential functions of M2-1 and its homologs in related viruses. Our work may contribute to identifying targets for antiviral inhibitors and advancing RSV infection treatment.

Indocyanine Green Fluorescence-Guided Laparoscopic Anatomical Segmentectomy of Liver Segment 6: Surgical Strategy and Technical Details.

Because of the complex anatomy of the right posterior hepatic pedicle, there have been few reports on standardized laparoscopic portal territory staining-guided anatomical resection of liver segment 6 (LPTAR-S6). This study aimed to elucidate the indocyanine green (ICG) fluorescence staining methods for LPTAR-S6. LPTAR-S6 can be performed using positive and negative fluorescence staining approaches. We implemented these two approaches for patients with hepatocellular carcinoma. Descriptions of the surgical strategy and technical details are presented. Two patients safely underwent LPTAR-S6 using a preoperative three-dimensional reconstruction plan. The intraoperative ICG fluorescence staining effect was satisfactory, and the anatomical landmarks were fully exposed. A detailed preoperative three-dimensional reconstruction plan, complete intraoperative application of real-time laparoscopic ultrasound guidance, and ICG fluorescence staining can result in accurate transection of the liver parenchyma during LPTAR-S6.

Structural Mapping of Polyclonal IgG Responses to HA After Influenza Virus Vaccination or Infection.

Cellular and molecular characterization of immune responses elicited by influenza virus infection and seasonal vaccination have informed efforts to improve vaccine efficacy, breadth, and longevity. Here, we use negative stain electron microscopy polyclonal epitope mapping (nsEMPEM) to structurally characterize the humoral IgG antibody responses to hemagglutinin (HA) from human patients vaccinated with a seasonal quadrivalent flu vaccine or infected with influenza A viruses. Our data show that both vaccinated and infected patients had humoral IgGs targeting highly conserved regions on both H1 and H3 subtype HAs, including the stem and anchor, which are targets for universal influenza vaccine design. Responses against H1 predominantly targeted the central stem epitope in infected patients and vaccinated donors, whereas head epitopes were more prominently targeted on H3. Responses against H3 were less abundant, but a greater diversity of H3 epitopes were targeted relative to H1. While our analysis is limited by sample size, on average, vaccinated donors responded to a greater diversity of epitopes on both H1 and H3 than infected patients. These data establish a baseline for assessing polyclonal antibody responses in vaccination and infection, providing context for future vaccine trials and emphasizing the importance of carefully designing vaccines to boost protective responses towards conserved epitopes.

Short-term effects of modified ultrasonography in laparoscopic anatomical hepatectomy for hepatocellular carcinoma

Background and aimsLaparoscopic hepatectomy is challenging, and ultrasound guidance is an effective aid but lacks standardization. This study aimed to evaluate a modified approach for laparoscopic ultrasonography to enhance surgical outcomes. MethodsBetween January 2020 and August 2023, 122 patients who underwent real-time ultrasound-guided laparoscopic anatomical hepatectomy for hepatocellular carcinoma were enrolled and divided into modified and traditional ultrasonography groups. The modified ultrasound application comprised intraoperative protocol-based laparoscopic ultrasonography comprising application scenarios; standardized positions for the surgeon, trocar, and probe; and the resulting standardized sections for various laparoscopic liver resections. Clinical characteristics and perioperative outcomes were compared between the two groups. Subgroup analysis was performed and comprised techniques for modified duct structure identification and portal vein branch puncture; both techniques were used in fluorescence probe-mounted laparoscopic liver resection using negative and positive staining procedures, respectively. ResultsThe traditional and modified groups comprised 64 and 58 patients, respectively. The patients’ background characteristics were not significantly different between the groups. Surgical duration (283.4 min vs. 225.1 min; p < 0.001), Pringle maneuver duration (47.4 min vs. 39.5 min; p = 0.014), bleeding volume (258.6 mL vs. 174.8 mL; p = 0.005), overall complication rate (31.3% vs. 15.5%; p = 0.041), and postoperative stay were significantly greater in the traditional vs. modified ultrasonography groups, respectively. The modified method positively affected the number of punctures, success rate of staining, intraoperative bleeding volume, and operation duration. ConclusionsModified ultrasonography improves the safety and effectiveness of laparoscopic hepatectomy. Ultrasonography is pivotal, especially in fluorescence probe-assisted laparoscopic liver resection.

Insulinoma-Associated Protein-1 Expression in Lymphoepithelial Carcinoma of the Thymus: A Potential Pitfall for Diagnosis With Neuroendocrine Carcinomas of the Thymus.

Insulinoma-associated protein-1 (INSM1) is a recently developed immunohistochemical marker claimed to be highly specific and sensitive for the diagnosis of neuroendocrine malignancies. Recent studies, however, have demonstrated that this marker can also be expressed in non-neuroendocrine neoplasms including squamous cell carcinoma of the thymus. To examine INSM1 expression in lymphoepithelial thymic carcinomas. Thirty-four cases of lymphoepithelial carcinoma of the thymus were examined by immunohistochemistry or in situ hybridization for INSM1, synaptophysin, chromogranin, CD5, CD117, Epstein-Barr virus-encoded small ribonucleic acid (EBER), and Ki-67. Basic clinical information was abstracted from the medical record. The patients were 14 women and 20 men, aged 20 to 85 years. The tumors arose in the anterior mediastinum without any previous history or evidence of malignancy at other sites. Immunohistochemical staining showed moderate to strong positivity of the tumor cells for INSM1 in 65% of cases (22 of 34), focal weak positivity in 20% (7 of 34), and negative staining in 5 cases. Chromogranin staining was focally and weakly positive in 1 case, and synaptophysin showed only focal weak positivity in scattered tumor cells in 12 cases. No significant correlation could be identified between the pattern and intensity of staining for INSM1 and staining for CD5, CD117, and Ki-67. INSM1 positivity in lymphoepithelial carcinoma of the thymus may represent a pitfall for diagnosis, particularly in small biopsy samples. Awareness of this finding may be of importance to avoid misdiagnosis of neuroendocrine malignancy.

Deep learning for automated scoring of immunohistochemically stained tumour tissue sections – Validation across tumour types based on patient outcomes

We aimed to develop deep learning (DL) models to detect protein expression in immunohistochemically (IHC) stained tissue-sections, and to compare their accuracy and performance with manually scored clinically relevant proteins in common cancer types.Five cancer patient cohorts (colon, two prostate, breast, and endometrial) were included. We developed separate DL models for scoring IHC-stained tissue-sections with nuclear, cytoplasmic, and membranous staining patterns. For training, we used images with annotations of cells with positive and negative staining from the colon cohort stained for Ki-67 and PMS2 (nuclear model), the prostate cohort 1 stained for PTEN (cytoplasmic model) and β-catenin (membranous model). The nuclear DL model was validated for MSH6 in the colon, MSH6 and PMS2 in the endometrium, Ki-67 and CyclinB1 in prostate, and oestrogen and progesterone receptors in the breast cancer cohorts. The cytoplasmic DL model was validated for PTEN and Mapre2, and the membranous DL model for CD44 and Flotillin1, all in prostate cohorts. When comparing the results of manual and DL scores in the validation sets, using manual scores as the ground truth, we observed an average correct classification rate of 91.5 % (76.9–98.5 %) for the nuclear model, 85.6 % (73.3–96.6 %) for the cytoplasmic model, and 78.4 % (75.5–84.3 %) for the membranous model. In survival analyses, manual and DL scores showed similar prognostic impact, with similar hazard ratios and p-values for all DL models. Our findings demonstrate that DL models offer a promising alternative to manual IHC scoring, providing efficiency and reproducibility across various data sources and markers.

Histologic Assessment of Lumbosacral Transitional Vertebrae Pseudoarticulation as a Source of Pain in Bertolotti Syndrome

BackgroundBertolotti's Syndrome (BS) is characterized by chronic pain and functional impairment associated with lumbosacral transitional vertebrae (LSTVs). The study aimed to investigate the histological characteristics of the pseudoarticulation between the enlarged transverse process and sacrum seen in Castellvi 2a LSTV and explore the involvement of nervous tissue in pain generation. MethodsImmunohistochemical analysis using S100 protein staining was performed to assess the presence of nerve tissue. ResultsThese changes included fibrillation, chondrocyte cloning, alterations in the proteoglycan matrix, and focal chondrocyte necrosis. Notably, no nerve tissue was observed in any of the specimens, as confirmed by negative S100 protein staining. ConclusionThe study findings suggest that nerve tissue is not involved in the nociceptive mechanisms underlying pain in BS. The histological similarities between the pseudoarticulation and osteoarthritic joints indicate that the pseudoarticulation itself may be a significant source of pain in BS. These insights contribute to our understanding of the pathophysiology of BS and support treatment paradigms prioritizing pain control with medications such as NSAIDs before considering surgical intervention. Future studies with larger sample sizes and in vivo models are needed to further validate these findings and explore the changes in joint histology under biomechanical forces in LSTVs.

Genetic variants and down-regulation of CACNA1H in pheochromocytoma.

Pheochromocytoma (PCC) and abdominal paraganglioma (aPGL) (together abbreviated PPGL) frequently present with an underlying genetic event in a PPGL driver gene, and additional susceptibility genes are anticipated. Here, we re-analyzed whole-exome sequencing data for PCC patients and identified two patients with rare missense variants in the calcium voltage-gated channel subunit 1H gene (CACNA1H). CACNA1H variants were also found in the clinical setting in PCC patients using targeted sequencing and from analysis of The Cancer Genome Atlas database. In total, CACNA1H variants were found in six PCC cases. Three of these were constitutional, and two are known to have functional consequences on hormone production and gene expression in primary aldosteronism and aldosterone-producing adrenocortical adenoma. In general, PPGL exhibited reduced CACNA1H mRNA expression as compared to normal adrenal. Immunohistochemistry showed strong CACNA1H (CaV3.2) staining in adrenal medulla while PPGL typically had weak or negative staining. Reduced CACNA1H gene expression was especially pronounced in PCC compared to aPGL and in PPGL with cluster 2 kinase signaling phenotype. Furthermore, CACNA1H levels correlated with HIF1A and HIF2A. Moreover, TCGA data revealed a correlation between CACNA1H methylation density and gene expression. Expression of rCacna1h in PC12 cells induced differential protein expression profiles, determined by mass spectrometry, as well as a shift in the membrane potential where maximum calcium currents were observed, as determined by electrophysiology. The findings suggest the involvement of CACNA1H/CaV3.2 in pheochromocytoma development and establish a potential link between the etiology of adrenomedullary and adrenocortical tumor development.

Immunohistochemical Expression of Human Epidermal Growth Factor Receptor 2 and Ki67 in Apocrine Gland Anal Sac Adenocarcinoma.

Apocrine gland anal sac adenocarcinoma is an aggressive neoplasm, and surgery remains the treatment of choice, although it is controversial in advanced cases. The prognostic factors are not well established. Human Epidermal Growth Factor Receptor 2 (HER2) is a membrane protein related to tumorigenesis, whereas Ki67 is a nuclear protein related to cell proliferation. Both are potential prognostic markers and therapeutic targets. This study aimed to evaluate the expression of HER2 and Ki67 markers in canine apocrine gland anal sac adenocarcinoma. The tumor samples were divided into four groups: largest tumor diameter less than 2.5 cm, largest tumor diameter greater than 2.5 cm, metastatic lymph nodes, and control group of non-neoplastic anal sacs. Each contained 10 samples. Immunohistochemistry was performed to verify the expression of HER2 and Ki67 markers. Positive HER2 staining was observed in 45% of the neoplastic cases and negative HER2 staining in 100% of the control group. The Ki67 expression had a median of 25% in all groups, except for the control group, which had a median of 8%. The HER2 and Ki67 expression was present in apocrine gland anal sac adenocarcinoma, making them potential therapeutic targets. However, it was not possible to determine the clinical value of either marker.

PCSK9 expression in fibrous cap possesses a marker for rupture in advanced plaque.

To date, PCSK9 inhibitors are well known for eliminating cardiac and cerebral artery ischemia events by lowering the serum lipid level. However, the pathophysiological value of in-plaque PCSK9 expression is still unclear. Advanced plaques removed by carotid endarterectomy were sectioned and stained to identify the PCSK9 expression pattern and its co-expression with rupture-relevant markers. To investigate the correlation of PCSK9 expression with regional blood shear flow, hemodynamic characteristics were analyzed using computational fluid dynamics, and representative parameters were compared between PCSK9 positive and negative staining plaques. To explore this phenomenon in vitro, human aortic vascular smooth muscle cells were used to overexpress and knock down PCSK9. The impacts of PCSK9 modulations on mechanical sensor activity were testified by western blot and immunofluorescence. Real-time polymerase chain reaction was used to evaluate the transcription levels of downstream rupture-prone effectors. PCSK9 distribution in plaque preferred cap and shoulder regions, residing predominantly in smooth muscle actin-positive cells. Cap PCSK9 expression correlated with fibrous cap thickness negatively and co-expressed with MMP-9, both pointing to the direction of plaque rupture. A hemodynamic profile indicated a rupture-prone feature of cap PCSK9 expression. In vitro, overexpression and knockdown of PCSK9 in human aortic vascular smooth muscle cells has positive modulation on mechanical sensor Yes-associated protein 1 (YAP) activity and transcription levels of its downstream rupture-prone effectors. Serial section staining verified in situ colocalization among PCSK9, YAP, and downstream effectors. Cap PCSK9 possesses a biomarker for rupture risk, and its modulation may lead to a novel biomechanical angle for plaque interventions.

Midkine Attenuates Aβ Fibril Assembly and AmyloidPlaque Formation.

Proteomic profiling of Alzheimer's disease (AD) brains has identified numerous understudied proteins, including midkine (MDK), that are highly upregulated and correlated with Aβ since the early disease stage, but their roles in disease progression are not fully understood. Here we present that MDK attenuates Aβ assembly and influences amyloid formation in the 5xFAD amyloidosis mouse model. MDK protein mitigates fibril formation of both Aβ40 and Aβ42 peptides in Thioflavin T fluorescence assay, circular dichroism, negative stain electron microscopy, and NMR analysis. Knockout of Mdkgene in 5xFAD increases amyloid formation and microglial activation. Further comprehensive mass spectrometry-based profiling of whole proteome and aggregated proteome in these mouse models indicates significant accumulation of Aβ and Aβ-correlated proteins, along with microglial components. Thus, our structural and mouse model studies reveal a protective role of MDK in counteracting amyloid pathology in Alzheimer's disease.

Unveiling a novel NKG2A inhibitor based on monoclonal antibody to HLAE-peptide complex.

e14677 Background: HLAE is a non-classical MHC class I molecule complexed with the VMAPRTLFL nonapeptide, derived from the leader sequence of HLAG (HLAEpHLAG). HLAEpHLAG is overexpressed across a wide type of tumors prominently on Multiple Myeloma (MM). HLAEpHLAG complex is the ligand to CD94-NKG2A in the immune system which negatively regulates the activation of natural killer (NK) cells as well as NKG2A positive T cells. Harnessing of the HLAE-NKG2A axis by the cancer cells leads to evasion from the immune system attack resulting in cancer progression. Currently, several Immune Checkpoint Inhibitors (ICIs) target the NKG2A receptor which has a low specificity to cancer and high toxicity to the patient. Engineering a new ICI that targets the HLAEpHLAG complex can potentially yield improved outcomes in cancer therapy. Methods: Using the hybridoma system, a new mouse monoclonal antibody (mAb) called 4D7 that targets the HLAEpHLAG complex was developed. mAb 4D7 affinity was assessed in vitro with recombinant proteins and a panel of cell lines that expressed zero to high levels of HLAE. The functional impacts of the mAb 4D7 was examined in a system where various MM cell lines were separately co-cultured with primary NK (pNK) cells. pNK were isolated from the peripheral blood of 5 healthy donors, and their activity was examined in the presence of mAb 4D7 by CD107a degranulation assay. Also, the functional impacts of the mAb 4D7 on allogenic pNK and MM blast cells, isolated from the bone marrow of 6 MM patients were assessed. Results: mAb 4D7 was determined to be an IgG-kappa isotype showing a high specific binding to recombinant HLAEpHLAG. Cell lines with overexpression of membranal HLAEpHLAG: RPMI8226, U266, 721.221 HLAE, and 721.221 HLAG showed positive staining with the mAb 4D7. While cell lines with low to zero expression of HLA-E like 721.221 WT showed low or negative staining with the mAb 4D7. The degranulation of NKG2A+ pNK subset cells against MM target cells increased in presence of mAb 4D7. However, adding mAb 4D7 to NKG2A -pNK subset cells co-cultured with MM target cells did not affect the pNK activity. Similar results were obtained when the target and effector cells were isolated from the bone marrow of active treatment-naive MM patients. Conclusions: MAb 4D7 demonstrates a remarkably high affinity for binding to the HLAEpHLAG complex, ensuring the safety of its application. The ability of 4D7 mAb to effectively block the HLAEpHLAG complex and counteract the inhibition signal in NK cells. mAb 4D7 is a promising monoclonal antibody with substantial potential to serve as an ICI for clinical use in MM patients.

Effect of aberrant N-glycosylation of PD-L1 on the potency of anti-PD-1 treatments.

e14599 Background: Immune checkpoint inhibitors (ICIs) targeting the PD1/PDL1 axis have revolutionized the way we treat cancer patient. Yet, response rate to these treatments remains low. Post translational modifications of PD-L1 in the form of N-glycosylation play a crucial role in both receptor-ligand interaction and in the potency of PD1/PDL1 ICIs. Understanding the effect of each N-glycosylation site is crucial for patient stratification for treatment groups and may help to increase response rate to anti-PD1/PDL1 ICIs. We recently developed the Immune-Checkpoint Artificial Reporter (IcAR) technology to assess specific ICI potency for target tumors including clinical samples. Using IcAR expressing recombinant human PD1 receptor we can analyze clinical response of patients to PD1-PDL1 blocking drugs and analyze the glycan-modified PDL1 expressing cancer cells. Methods: We have created two cell lines (MDA-MB231 and MCF7) overexpressing PD-L1 in its wildtype form, single mutated glycosylation sites (N35A, N192A, N200A, N219A) and all sites mutated together (Nx4). Using IcAR-PD1 we measured the functional binding of the different mutated cell lines, cell derived xenografts (CDX) and fixed cell samples to evaluate baseline binding. Later we have incubated IcAR-PD1 and mutated cell liens together with multiple clinically used PD1/PDL1 ICIs to evaluate the inhibition of interaction of each ICI. Results: While staining and functional interaction of PDL1 and single mutants is similar, removing all four N-glycosylation sites (Nx4) decreased both the staining of PDL1 and functional binding. Interestingly, blocking capacity of different ICIs was impaired by N35A PDL1 mutation, and was absolute through all concentration (2.5 to 40 ug/mL) when employed on the Nx4 cell lines. While anti-PDL1 ICIs were managed to block PD-1/PD-L1 interaction trough all cell lines and mutants, the inhibitory capacity of anti-PD1 ICIs was impaired by glycosylation, especially on N35. Conclusions: Aberrant glycosylation of PD-L1 impair the potency of anti-PD-1 treatment in cancer cell lines. These results might explain why patients with negative PD-L1 staining (Nx4), might respond to ICIs, and suggest an explanation of mechanism in which patients with high PD-L1 staining (i.e. N35), might not respond to anti-PD-1 treatments. Our results shed a light on the mechanism of ICI resistance and response – using this knowledge patient will be stratify better into treatment groups, getting oncology a step closer to precision immunology.

Identifying mutations in ctDNA to predict antibody-drug conjugate response in breast cancer.

e13074 Background: Metastatic breast cancer (mBC) is a complex disease, and outcomes remain poor because new therapies are needed. A new class of drugs, antibody-drug conjugate (ADC), has shown effectiveness across all breast cancer subtypes. Yet FDA- approval for these therapies is restricted only to HER2 and triple-negative subtypes. Therefore, we urgently need to identify which patients, regardless of subtype, will respond to ADCs. The advent of circulating tumor DNA (ctDNA) offers a unique noninvasive method to capture breast cancer (BC) heterogeneity. Recently, ctDNA testing has been employed in clinical practice to guide targeted therapies for mBC, particularly in cases of hormone receptor positive (HR+) disease with mutations in PIK3CA and ESR1. The clinical implications to predict response to ADC therapy in BC remains unclear. Here we test the hypothesis that ctDNA can detect mutations that predict response to novel ADCs. Methods: We analyzed a subset of patients from the Dallas Metastatic Breast Cancer Study comprised of patients with mBC who underwent ctDNA testing using the Tempus xF liquid biopsy ctDNA sequencing panel. The data was analyzed from a single academic medical center between the initial year of ctDNA collection in 2019 to 2023. We identified detectable mutations from patients and addressed a relationship by using Metascape. Relevant signaling pathways were identified: APOBEC, ErbB signaling, p53 and Ras-MAPK pathway. Patients with triple negative, HER2, and HR BC were examined for ADC response and associated mutations. Survival analyses were estimated using Kaplan-Meier and Gehan Breslow Wilcoxon test for statistical analysis. Results: We identified 43 patients with HR+ mBC who had at least one mutation within the Ras-MAPK pathway and 10 of 43 received ADC therapy. Median survival of patients who received ADC therapy 58 months (n=10) vs not receiving ADC therapy 33 months (n=33) (p &lt; 0.05). Of the ten patients who received ADC treatment, 60% had 1+ HER2 staining on tissue biopsy. 70% of patients received Trastuzumab deruxtecan (T-DXd) and 30% received Sacituzumab govitecan (SG). SG was given to patients with negative HER2 staining on biopsy. Patients with at least one mutation within ABOBEC, ErbB signaling, and p53 pathways did not have statistically significant differences in mOS. Conclusions: In HR+ mBC, detection of mutated genes associated with the Ras-MAPK pathway by ctDNA was associated with a more favorable response when treated with ADCs. These findings are exciting because HR+ BCs are being targeted with ADCs regardless of HER2 or TROP2 expression, highlighting the need for new biomarkers to distinguish which HR+ patients to treat. Our retrospective analysis findings are limited by the number of patients with ctDNA testing and also timing of testing. Further studies are needed to solidify the observed correlation between Ras-MAPK pathway mutations and favorable response to ADC treatment.

Rapidly Growing Congenital Disseminated Pyogenic Granuloma in the Scalp Treated with Staged Embolization and Excision: A Case Report

Pyogenic granulomas are common, acquired vascular lesions that most often arise spontaneously or in sites of previous trauma. However, there are reports of a few cases that describe a rare condition, congenital disseminated pyogenic granuloma (CDPG), in which an infant either is born with or shortly after birth develops multiple pyogenic granulomas. A hallmark of CDPG is negative staining for glucose transporter 1 (GLUT-1) on immunohistochemistry, which helps distinguish it from the more common multifocal infantile hemangiomas. Because few case reports have described CDPG, much is unknown about its characteristics, clinical course, and most effective treatment options. Here, we present a case of an infant with a unique presentation of CDPG with lesions that are atypically large and growing at a rapid pace. We also describe a novel approach to treating large pyogenic granulomas in CDPG via staged glue embolization and surgical excision.

Molecular characterization of breast cancer cell lines in correlation with clinical markers

Cell lines are indispensable for biomedical research, offering a consistent platform for investigating cellular processes and disease mechanisms. Despite their value, cell lines possess limitations such as genetic drift and phenotypic alterations over successive passages, potentially compromising their relevance. Monoclonal derivation may not represent in vivo heterogeneity, particularly in cancer. Therefore, characterizing them becomes imperative. We aimed to identify breast cancer subtype-specific cell lines by assessing ER, PR, and HER-2 expression via immunohistochemistry and their concordance with molecular expression. We selected cell lines with consistent phenotypes that mimic primary cells and confirmed concordance in ER, PR, and HER-2 expression at protein and mRNA levels. Evaluation of ER, PR, and HER-2 was conducted using Immunocytochemistry (ICC), Immunofluorescence (IF), and real-time PCR across commonly used breast cancer cell lines. Results revealed differential expression patterns, with MCF-7 and T-47D cells showing positive ER and PR staining but negative HER-2 staining, while SK-BR-3 and HCC1954 cells exhibited positive HER-2 staining and negative ER and PR staining. Conversely, MDA-MB-231 and MDA-MB-468 cells displayed negative staining for all three markers. Real-time PCR analysis highlighted variations in HER-2 expression among the cell lines. Our investigation underscores MCF-7, SK-BR-3, MDA-MB-231, and MDA-MB-468 cell lines as pertinent models for studying major molecular subtypes of breast cancer.