Oligomerization-driven avidity correlates with SARS-CoV-2 cellular binding and inhibition.

Cellular processes are controlled by the thermodynamics of the underlying biomolecular interactions. Frequently, structural investigations use one monomeric binding partner, while ensemble measurements of binding affinities generally yield one affinity representative of a 1:1 interaction, despite the majority of the proteome consisting of oligomeric proteins. For example, viral entry and inhibition in SARS-CoV-2 involve a trimeric spike surface protein, a dimeric angiotensin-converting enzyme 2 (ACE2) cell-surface receptor and dimeric antibodies. Here, we reveal that cooperativity correlates with infectivity and inhibition as opposed to 1:1 binding strength. We show that ACE2 oligomerizes spike more strongly for more infectious variants, while exhibiting weaker 1:1 affinity. Furthermore, we find that antibodies use induced oligomerization both as a primary inhibition mechanism and to enhance the effects of receptor-site blocking. Our results suggest that naive affinity measurements are poor predictors of potency, and introduce an antibody-based inhibition mechanism for oligomeric targets. More generally, they point toward a much broader role of induced oligomerization in controlling biomolecular interactions.

Long-term outcomes after resection of extra-ampullary duodenal adenocarcinomas: single-center experience.

BACKGROUND: Extra-ampullary duodenal adenocarcinoma is a rare neoplasm. The data on long-term outcomes after curative resection are limited, and the role of systemic chemotherapy is not defined in these tumors. This study aimed to investigate the prognostic factors and survival of patients with resected primary duodenal cancers. METHODS: A retrospective analysis of patients with resected primary duodenal adenocarcinoma was conducted between January 2010 and December 2023. RESULTS: A total of 59 patients were included in the study. The median age of patients was 60 years (IQR, 33-79), and 79.7% of patients were males. The second part of the duodenum was the most common location of the tumor in 42 patients (71.2%). Pancreaticoduodenectomy was performed in 57 patients (96.6%), and segmental duodenal resection was performed on 2 patients (3.4%). The median lymph node harvest was 18 (IQR, 2-70). Adjuvant chemotherapy was administered to 39 patients (66.1%). At a median follow-up of 32.00 months (IQR, 3.29-166.74), the 5-year overall survival (OS) and disease-free survival rates were 55.0% and 49.3%, respectively. Regarding prognostic factors, lymph node ratio (LNR; hazard ratio [HR], 2.94; 95% CI, 1.01-8.53), adenocarcinoma subtype (intestinal vs nonintestinal; HR, 4.59; 95% CI, 1.59-13.23), and margin of resection (HR, 44.24; 95% CI, 4.02-486.19) were significant factors for OS. CONCLUSION: Margin-free surgical resection offers the best chance of cure for operable duodenal adenocarcinoma. The intestinal subtype and low LNR are predictors of better survival, and the role of adjuvant chemotherapy remains debatable until prospective randomized trials are conducted.

Immunoaffinity-free chromatographic purification of ovarian cancer biomarker CA125 (MUC16) from blood serum enables mass spectrometry characterization.

The enrichment of trace proteins from human fluid samples is of great importance in diverse clinical and industrial applications. In clinical diagnostics, such enrichment may enable detection of trace proteins that serve as biomarkers of disease. Affinity-based approaches, such as immunoaffinity pulldown, are widely used to enrich trace proteins, but this strategy relies on the availability and performance of antibodies that act on all proteoforms in an unbiased manner. Our prior work to characterize MUC16 (the mucin protein that carries the ovarian cancer biomarker CA125) by mass spectrometry successfully overcame the reliance on affinity-based enrichment and was used to enrich this biomarker from ascites of individual ovarian cancer patients, however, this strategy was not demonstrated on clinically relevant volumes of serum, a biofluid that is more accessible than ascites. The present work developed a non-affinity-based chromatographic method to enrich MUC16 from serum. The enriched MUC16 sample was further processed using a Midi Top 14 abundant protein depletion column. Peptides identified using bottom-up proteomics yielded 1-8% coverage of MUC16. Additionally, MUC16 was detected in samples containing less than the clinical cut-off level of CA125 (35 U mL-1), suggesting that this strategy of enrichment and bottom-up proteomics can enable analysis of CA125 from the serum of individuals with early-stage ovarian cancer and those whose tumors express CA125 (MUC16) at low levels.

Validation and Optimisation of the ISGPS Risk Classification for Postoperative Pancreatic Fistula after Pancreatoduodenectomy for Periampullary Tumours.

OBJECTIVES: To externally validate the International Study Group of Pancreatic Surgery (ISGPS) classification and test its performance for predicting clinically relevant pancreatic fistula (CRPF) for periampullary tumours (P-amps). BACKGROUND: The ISGPS is a simple two-factor, four-tier classification of pancreas-related risk for CRPF after a pancreatoduodenectomy (PD). External validation and performance of the classification specific to P-amps are lacking. P-amps have different disease biology, lesser need for neoadjuvant therapy, softer pancreas, and a higher rate of CRPF, underscoring the importance of site-specific prediction. METHODS: Validation was performed in a cohort of 1422 patients, with CRPF as the primary outcome. Model performance was tested by plotting the receiver operating curve and calibration plots. After analysing the factors predicting CRPF, the model was optimised for P-amps. RESULTS: CRPF rate was 22.2% (315/1422), for P-amps being 25.8%. The ISGPS model performed moderately (AUC=0.632, 95% CI 0.598-0.666, P<0.001), with worse performance for P-amps (AUC=0.605, 95% CI 0.566-0.645, P<0.001). On multivariate analysis, soft pancreas (OR 1.689, 95% CI 1.136-2.512, P=0.010), body mass index ≥23 kg/m2 (OR 2.112, 95% CI 1.464-3.046, P<0.001) and pancreatic duct ≤3 mm (OR 2.113 95% CI 1.457-3.064, P<0.001), emerged as independent predictors and the model was optimised. The adjusted ISGPS for P-amps showed improved discrimination (AUC=0.672, P<0.001, 95% CI 0.637-0.707), with adequate performance on internal validation. CONCLUSION: The adjusted ISPGS performs better than the original ISGPS in predicting CRPF for P-amps. Large-scale multicenter data is needed to generate and validate site-specific predictive models.

Evolution and improved outcomes in the era of multimodality treatment for extended pancreatectomy.

BACKGROUND: The evolution and outcomes of extended pancreatectomies at a single institute over 15 years are presented in this study. METHODS: A retrospective analysis of the institutional database was performed from 2015 to 2022 (period B). Patients undergoing extended pancreatic resections, as defined by the International Study Group for Pancreatic Surgery, were included. Perioperative and survival outcomes were compared with data from 2007-2015 (period A). Regression analyses were used to identify factors affecting postoperative and long-term survival outcomes. RESULTS: A total of 197 (16.1%) patients underwent an extended resection in period B compared to 63 (9.2%) in period A. Higher proportions of borderline resectable (5 (18.5%) versus 51 (47.7%), P = 0.011) and locally advanced tumours (1 (3.7%) versus 24 (22.4%), P < 0.001) were resected in period B with more frequent use of neoadjuvant therapy (6 (22.2%) versus 79 (73.8%), P < 0.001). Perioperative mortality (4 (6.0%) versus 12 (6.1%), P = 0.81) and morbidity (23 (36.5%) versus 83 (42.1%), P = 0.57) rates were comparable. The overall survival for patients with pancreatic adenocarcinoma was similar in both periods (17.5 (95% c.i. 6.77 to 28.22) versus 18.3 (95% c.i. 7.91 to 28.68) months, P = 0.958). Resectable, node-positive tumours had a longer disease-free survival (DFS) in period B (5.81 (95% c.i. 1.73 to 9.89) versus 14.03 (95% c.i. 5.7 to 22.35) months, P = 0.018). CONCLUSION: Increasingly complex pancreatic resections were performed with consistent perioperative outcomes and improved DFS compared to the earlier period. A graduated approach to escalating surgical complexity, multimodality treatment, and judicious patient selection enables the resection of advanced pancreatic tumours.

Associations of demographic and tobacco use characteristics with young adults' self-reported clinical encounters: Implications for cessation efforts.

Introduction: Accelerating smoking cessation, particularly among young adults, is a national priority for decreasing tobacco-related disease. Healthcare providers play a critical role in delivering tobacco treatment interventions to this population. This study examined associations of demographic and tobacco use characteristics with young adults' self-reported past-year clinical encounters to identify opportunities to facilitate cessation. Methods: We conducted cross-sectional, secondary analyses on a sample of 831 young adults aged 18-34 participating in the first wave of the National Young Adult Health Survey (NYAHS 2018-2019). Demographic and tobacco use characteristics were participants' sex, age, race, current cigarette use, and current other tobacco use. Clinical encounter outcomes were past-year self-report of (1) seeing a clinician, (2) being asked about tobacco use, and among those currently smoking, (3) being advised to quit smoking. Results: After adjustment for covariates, women (vs. men) had 2.16 times greater odds of reporting seeing a clinician, while Non-White (vs. White) young adults and those currently (vs. never) smoking had 69% and 47% lower odds. Women and those currently smoking had 2.98 and 2.66 times greater odds, respectively, of being asked about tobacco use. Among those who currently smoked, being not confident (vs. confident) about quitting smoking was associated with 69% lower odds of being advised to quit; those who reported moderate (vs. low) nicotine dependence had 3.11 times higher odds of being advised to quit. Conclusions: Sex, racial, and smoking status differences in young adults' clinical encounter outcomes suggest multiple opportunities for future smoking prevention and cessation intervention efforts.

1657 Resected Gastric Adenocarcinomas at a Single Institution: Outcomes and Trends over 17 Years.

BACKGROUND: Outside of clinical trials, real-world data of advanced gastric cancers (AGCs) managed with perioperative or adjuvant chemotherapy with a backbone of D2 lymphadenectomy is limited. PATIENTS AND METHODS: Curative resections for gastric adenocarcinoma between January 2003 and January 2020 at the Tata Memorial Centre were analyzed, comparing three time periods marking major increments in annual gastric resections (GRs). RESULTS: 1657 radical gastric resections were performed with a morbidity and mortality rate of 34.9% and 1.4%, respectively. Over three consecutive periods, the number of annual GRs increased from 56/year to 97/year to 156/year (P < 0.001) with a significant escalation in surgical magnitude and complexity. Improvement in surgical quality indicators (median lymph node yield from 15 to 25, P < 0.001 and margin negativity from 8.2 to 5.5%, P = 0.002) was observed with no corresponding increase in severe complications (6.9%) or mortality (1.4%). The proportion of distal and signet ring cancers was found to decrease over time, with an increase in proximal cancers and younger age at presentation. Overall, 90% of GRs were for AGCs with a median overall survival (OS) of 4.4 years (± 6 months), and 5-year OS rate of 47.6% (± 1.9%). CONCLUSIONS: Change in pattern of tumor characteristics was observed. Aggressive treatment options for AGC were employed progressively with excellent survival. With increase in volumes, improvements in surgical quality indicators, and a relative improvement in postoperative mortality was observed. These results provide a roadmap for developing dedicated gastric cancer centers.

CA 19-9 Surveillance Detects Recurrences Early and Contributes to Improvement in Survival in Resected Ampullary Cancers: Analysis of 572 cases.

OBJECTIVE: To determine the clinical utility of serum CA 19-9 surveillance for detecting recurrences in resected ampullary carcinomas (ACs). INTRODUCTION: Although an established prognostic marker for pancreatic ductal adenocarcinoma, the value of CA 19-9 in resected ACs during follow-up is unknown. METHODS: Retrospective analysis of ACs undergoing pancreaticoduodenectomy at Tata Memorial Centre-Mumbai, from January 2012 to January 2020 was performed. Survival, recurrence patterns, factors associated with recurrences and the utility of CA 19-9 surveillance were assessed. RESULTS: The 5-year OS of 572 included patients with ACs, was 56.4%. There were 251(43.88%) recurrences, majority being distant (n=223). Higher 'T' & 'N' stage, margin involvement, perineural invasion, poor tumour differentiation and pancreatobiliary subtype were associated with poor outcomes. Optimal CA 19-9 level to predict recurrence was 77.85 U/mL (sensitivity-61.22%, specificity-76.67%, AUC-0.711); however, a serial rise was a more accurate predictor (sensitivity-71.05%, specificity-91.67%). The median duration between the first rise in CA 19-9 (>37 U/mL) and radiological evidence of recurrence was 4.04 months. The optimal level of relative rise in CA 19-9 in diagnosing a recurrence was established at 2.79x (sensitivity-46.26%, specificity-83.33%, AUC-0.614). A serial rise and absolute value of >200 U/mL was associated with recurrence in 87% & 92.9% of cases. Recurrence detection & treatment after serum CA 19-9 elevation was associated with superior median survival as compared to recurrence detection without elevation (12.8 mo vs. 7.6 mo, P=0.005). CONCLUSION: Serum CA 19-9 testing during follow-up evaluation detects recurrences early and improves survival in resected ACs, and therefore should be recommended as a routine surveillance test.

Differential impact of incrementally elevated CA 19-9 levels on prognosis of resected pancreatic ductal adenocarcinoma.

BACKGROUND: CA 19-9 is an extremely useful biomarker for pancreatic ductal adenocarcinomas (PDACs). However, the optimal cut-off and prognostic significance at higher cut-offs are yet to be determined. METHODS: Retrospective analysis included patients with PDAC who underwent curative resection from January 2010 to May 2020 at Tata Memorial Centre, Mumbai. The pretherapy CA 19-9 was dichotomized using various cut-off levels and analysed. RESULTS: In 244 included patients, the median overall survival (OS) for those with CA19-9 level (IU/ml) < or >78, 200, 500, 1000, and 2000 was 27, 24, 23, 22, 21 months versus 18, 16, 15, 14, 13 months; respectively, and was statistically significant (p-value- 0.002, 0.001, 0.002, 0.002 and 0.004, respectively). The number of recurrences and mortality had significant correlation with CA 19-9 cut-offs. On multivariate analysis, adjuvant treatment completion (p-0.004) and decreasing or stable CA19-9 after Neoadjuvant therapy (NAT) (p- 0.031) were associated with improved OS. CONCLUSION: The prognostic significance of CA 19-9 was observed at all the cut-off levels examined, beyond mere elevated value as per the standard cut-off level. In patients with high CA19-9 level, surgery should be offered if technically and conditionally feasible, only when a response in CA19-9 level to NAT is achieved.

Factors Predicting Prognosis in Metastatic Grade 1 Gastro-entero-pancreatic Neuroendocrine Tumors.

INTRODUCTION: The incidence of gastroenteropancreatic neuroendocrine tumors (GEP-NET) has steadily increased. These tumors are considered relatively indolent even when metastatic. What determines survival outcomes in such situations is understudied. MATERIALS AND METHODS: Retrospective analysis of a prospectively maintained NET clinic database, to include patients of metastatic grade 1 GEP-NET, from January 2018 to December 2021, to assess factors affecting progression-free survival (PFS). RESULTS: Of the 589 patients of GEP-NET treated during the study period, 100 were grade 1, with radiological evidence of distant metastasis. The median age was 50 years, with 67% being men. Of these, 15 patients were observed, while 85 patients received treatment in the form of surgery (n = 32), peptide receptor radionuclide therapy (n = 50), octreotide LAR (n = 22), and/or chemotherapy (n = 4), either as a single modality or multi-modality treatment. The median (PFS) was 54.5 months. The estimated 3-year PFS and 3-year overall survival rates were 72.3% (SE 0.048) and 93.4% (SE 0.026), respectively. On Cox regression, a high liver tumor burden was the only independent predictor of PFS (OR 3.443, p = 0.014). The 5-year OS of patients with concomitant extra-hepatic disease was significantly lower than that of patients with liver-limited disease (70.7% vs. 100%, p = 0.017). CONCLUSION: A higher burden of liver disease is associated with shorter PFS in patients with metastatic grade I GEP-NETs. The OS is significantly lower in patients with associated extrahepatic involvement. These parameters may justify a more aggressive treatment approach in metastatic grade 1 GEP-NETs.

A Perspective Review: Analyzing Collagen Alterations in Ovarian Cancer by High-Resolution Optical Microscopy.

High-grade serous ovarian cancer (HGSOC) is the predominant subtype of ovarian cancer (OC), occurring in more than 80% of patients diagnosed with this malignancy. Histological and genetic analysis have confirmed the secretory epithelial of the fallopian tube (FT) as a major site of origin of HGSOC. Although there have been significant strides in our understanding of this disease, early stage detection and diagnosis are still rare. Current clinical imaging modalities lack the ability to detect early stage pathogenesis in the fallopian tubes and the ovaries. However, there are several microscopic imaging techniques used to analyze the structural modifications in the extracellular matrix (ECM) protein collagen in ex vivo FT and ovarian tissues that potentially can be modified to fit the clinical setting. In this perspective, we evaluate and compare the myriad of optical tools available to visualize these alterations and the invaluable insights these data provide on HGSOC initiation. We also discuss the clinical implications of these findings and how these data may help novel tools for early diagnosis of HGSOC.

Impact of pCR after neoadjuvant chemotherapy and radical D2 dissection in locally advanced gastric cancers: Analysis of 1001 cases.

BACKGROUND: Advances in perioperative chemotherapy have improved outcomes in patients with gastric cancers (GC). This strategy leads to tumour downstaging and may result in a pathologic complete response (pCR). The study aimed to evaluate the predictors of pCR and determine the impact of pCR on long-term survival. METHODS: At the Department of Gastrointestinal and HPB Oncology at the Tata Memorial Centre, Mumbai, 1001 consecutive patients with locally advanced GCs undergoing radical resection following neoadjuvant chemotherapy from January 2005 to June 2022 were included. RESULTS: At a median follow-up of 61 months, the median OS was 53 months with a 5-year OS of 46.8 %. Ninety-five patients (9.49 %) realized pCR. Non-signet and well-differentiated histology were associated with pCR. pCR was significantly associated with improved OS, 5-year OS 79.2 % vs 43.2 % (HR 0.30, p < 0.001). On multivariable analysis, the realization of pCR and completion of adjuvant chemotherapy had superior OS. Whereas, signet-ring histology, linitis-like tumours, and high lymph node ratio had adverse outcomes. CONCLUSION: Tumour grade and signet-ring histology predict achievement of pCR in locally advanced GCs after neoadjuvant chemotherapy. Patients with pCR have significantly improved survival. Future neoadjuvant strategies should focus on enhancing pCR rates to improve overall outcomes.

Central versus distal pancreatectomy for low-grade and benign pancreatic neck-body tumours.

PURPOSE: Central pancreatectomy (CP) offers parenchymal preservation compared to conventional distal pancreato-splenectomy for pancreatic neck and body tumours. However, it is associated with more morbidity. This study is aimed at evaluating the peri-operative and long-term functional outcomes, comparing central and distal pancreatectomies (DPs). METHODS: Retrospective analysis of patients undergoing pancreatic resections for low-grade malignant or benign tumours in pancreatic neck and body was performed (from January 2007 to December 2022). Preoperative imaging was reviewed for all cases, and only patients with uninvolved pancreatic tail, whereby a CP was feasible, were included. Peri-operative outcomes and long-term functional outcomes were compared between CP and DP. RESULTS: One hundred twenty-two (5.2%) patients, amongst the total of 2304 pancreatic resections, underwent central or distal pancreatectomy for low-grade malignant or benign tumours. CP was feasible in 55 cases, of which 23 (42%) actually underwent CP and the remaining 32 (58%) underwent DP. CP group had a significantly longer operative time [370 min (IQR 300-480) versus 300 min (IQR 240-360); p = 0.002]; however, the major morbidity (43.5% versus 37.5%; p = 0.655) and median hospital stay (10 versus 11 days; p = 0.312) were comparable. The long-term endocrine functional outcome was favourable for the CP group [endocrine insufficiency rate was 13.6% in central versus 42.8% in distal (p = 0.046)]. CONCLUSION: Central pancreatectomy offers better long-term endocrine function without any increased morbidity in low malignant potential or benign pancreatic tumours of neck and body region.

Robotic Pancreaticoduodenectomy with 'SMA-First Approach (Posterior and Right Medial)' and 'Triangle Operation'.

BACKGROUND: Notable improvements in pancreatic cancer surgery have been due to utilization of the superior mesenteric artery (SMA)-first approach1 and triangle operation (clearance of triangle tissue between origin of SMA and celiac artery).2 The SMA-first approach was originally defined to assess resectability before taking the irreversible surgical steps. However, in the present era, resectability is judged by the preoperative radiology, and the benefit of the SMA-first approach is by improving the R0 resection rate and reducing blood loss. The basic principle is to identify the SMA at its origin and in the distal part, to guide the plane of uncinate dissection. This video demonstrates the combination of the posterior and right medial SMA-first approach along with triangle clearance during robotic pancreaticoduodenectomy (RPD). METHODS: The technique consisted of early dissection of SMA from the posterior aspect, by performing a Kocher maneuver using the 'posterior SMA-first approach'. The origin of the celiac artery, along with the SMA, was defined early in the surgery. During uncinate process dissection, the 'right/medial uncinate approach' was used to approach the SMA. 'Level 3 systematic mesopancreatic dissection' was performed along the SMA,3 culminating in the 'triangle operation'.2 RESULTS: The procedure was performed within 600 min, with a blood loss of 150 mL and no intraoperative or postoperative complications. The final histopathology report showed a moderately differentiated adenocarcinoma (pT2, pN2), with all resection margins free. CONCLUSION: The standardized technique of the SMA-first approach and triangle clearance during RPD is demonstrated in the video. Prospective studies should further evaluate the benefits of this procedure.

Primary Pancreatic GIST - A-Single Centre Case Series and Systematic Review of Literature.

PURPOSE: GISTs arising from organs outside GI tract are defined as extragastrointestinal GISTs (EGIST). The majority of EGISTs arise from small intestinal mesentry, mesocolon, omentum, retroperitoneum, abdominal wall, liver and pancreas with pancreas comprising less than 5% of it. Due to limited data, it is unknown if the results of GIST can be generalised for EGISTs. We thereby present the largest single-centre case series of primary pancreatic GIST so far with review of existing literature. METHODS: A total of 9 patients of primary pancreatic GIST were treated at our institute from September 2016 to February 2023. After literature search for all studies published before February 2023, 51 articles including 57 patients were identified. Their clinicopathological data and survival analysis were assessed. RESULTS: The median age of patients treated at our centre was 53 years with a female predominance. The most common epicentre was pancreatic head with abdominal pain as the most common presenting symptom. All 57 patients documented in literature belonged to a similar age group with similar gender predilection. The factors impacting DFS were histologic type, mitotic index, NIH risk category and adjuvant therapy. The median DFS was 74 months with a 5-year DFS being 71.9%, while the 5-year OS was 90.4%. CONCLUSION: Pancreatic GIST is a rare entity. Due to limited evidence and evolving literature, results cannot be generalised to a larger population. Larger case series with longer follow-up data are required to further understand the disease biology and long-term outcomes of pancreatic GIST.