PURPOSE:To report the primary analysis of a multicenter, phase III randomized trial of adjuvant radiotherapy (RT) after chemotherapy and radical cystectomy (RC) in patients with high-risk muscle-invasive bladder cancer (MIBC). METHODS:Patients with nonmetastatic urothelial MIBC at high risk after RC (any one of: T3-4, N1-3, margin positive, ≤10 nodes dissected) were randomly assigned 1:1 to adjuvant RT or observation (Obs), stratified by nodal involvement (yes/no) and chemotherapy (neoadjuvant/adjuvant/none). Stoma-sparing IG-IMRT 50.4Gy in 28 fractions was prescribed to the cystectomy bed and pelvic nodes. The primary end point was 2-year locoregional recurrence-free survival (LRFS), and the secondary end points were disease-free survival (DFS), bladder cancer-specific survival (BCSS), and overall survival (OS). RESULTS:From June 2016 to May 2024, 153 patients were randomly assigned (Obs = 76, RT = 77), with 62% and 41% of patients having pT3-T4 and pN+ stages, respectively. Over 90% of the patients received systemic chemotherapy (71% neoadjuvant and 20% adjuvant), and none received immunotherapy. After a median follow-up of 47 months, the 2-year LRFS was significantly higher with adjuvant RT versus observation (87.1% v 76.0%, hazard ratio [HR], 0.43 [95% CI, 0.20 to 0.96], P = .04). The DFS was 71.6% versus 58.7% (HR, 0.62 [95% CI, 0.36 to 1.05]), BCSS was 79.6% versus 65.0% (HR, 0.59 [95% CI, 0.33 to 1.10]), and OS was 70.4% versus 57.4% (HR, 0.78 [95% CI, 0.49 to 1.26]) for RT and Obs, respectively. CONCLUSION:Adjuvant pelvic IMRT after radical cystectomy and perioperative chemotherapy suggests an improvement in locoregional control in patients with high risk urothelial MIBC with no additional severe toxicity.

Abstract Background: TP53 is the most frequently altered tumor suppressor gene in cancer, yet the distribution, functional consequences, and genomic correlates of its diverse mutation classes vary across tumor types and disease stages. Advanced cancers profiled in real-world testing environments offer unique insight into late-stage genomic evolution pressures. In this study we characterized the prevalence, functional features[AP1] , and genomic context of TP53 mutations (mTP53) detected across breast (BC), colorectal (CRC), and lung (LC) cancers using a combined plasma- and tissue-derived sequencing cohort. Methods: Comprehensive genomic profiling was performed on 1187 patients (827 ctDNA; 360 tDNA) with advanced solid tumors (BC=358, CRC=300, LC=529). Sequencing was conducted using a hybrid-capture OncoIndx 1080-gene NGS assay interrogating SNVs, small indels, structural variations and genomwwide tumor mutation burden (TMB) and homologous recombination deficiency (HRD) scores. mTP53 were classified by variant type (missense (MS), nonsense (NS), frameshift (FS), splice variants (SPlv) and short indels (IND) and predicted function (loss-of-function: LOF and gain-of-function: GOF). Co-mutation patterns with canonical oncogenic drivers were assessed across lineages. Results: In ctDNA, mTP53 were detected in 50.5% (600/1187) of all cases, with highest prevalence in CRC (57.33%), followed by BC (53%), and LC (45%). Missense variants accounted for 65.8% of all mTP53, including recurrent GOF hotspots at R175, R248, R273, and G245, the latter being most prominent in CRC. GOF mutations accounted for 33.3% of all mTP53. NS, FS, Splv and indels comprised 16.6%, 7.5%, 7.0%, 3.1%, respectively. Across the cohort, mTP53 tumors exhibited significantly higher TMB than wtTP53 counterparts (P<0.0001, OR= 3.3, CI= 1.9-5.6). Within mTP53, GOF variants were associated with high TMB. However, In BC, mTP53 was associated with low HRD scores (P= 0.0017, OR= 0.28, CI=0.13-0.6), demonstrating lineage specific genomic behavior. GOF mTP53 tumors showed high PD-L1 expression compared to LOF mTP53 tumors (P=0.001). Co-mutation analysis revealed lineage-specific associations, including TP53-KRAS co-alteration in CRC, TP53-EGFR/ TP53-KRAS in LC and TP53-PIK3CA pairing in BC. GOF mTP53 were enriched in tumors with liver or brain metastasis and showed worse prognosis in LC. Conclusion: This large real-world dataset reveals tumor-type-specific mTP53 patterns and suggests that TP53 dysfunction, particularly GOF variants, is significantly associated with genomic instability signatures, such as elevated TMB in advanced disease. Lineage-specific co-mutation networks and enrichment of GOF mTP53 highlight distinct evolutionary pressures and will further support mechanistic and clinical studies to define the therapeutic and prognostic implications of mTP53 in solid tumors. [AP1]Not too sure what you mean by functional features here. Citation Format: Atul Bharde, Devika Deshmukh, Pooja Sant, Hrishita Kothavade, Sandhya Iyer, Sumit Halder, Ajay Pandita, Mohan Uttarwar, Gowhar Shafi, Kumar Prabhash. Precision profiling of TP53 alterations in advanced cancers: Real-world evidence linking mutation class to genomic instability and cooccurring actionable drivers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(8_Suppl):Abstract nr LB118.

Loss of expression of TTF1 and PAX8 in primary thyroid malignancies raises concerns for metastatic disease in addition to a high-grade primary tumor. Precise distinction is critical, as treatment strategies differ. Herein, we present the case of a 74-year-old man with a right-sided neck swelling, and change in voice for 2 months. Clinically, a 6 cm restricted mobility mass involving thyroid was detected, which on CT scan showed abutment of trachea and esophagus, along with right cervical and upper-mediastinal lymphadenopathy. Biopsies from right thyroid lobe and right supraclavicular node showed an infiltrative carcinoma in nests and cords, a distinct squamoid appearance, focal rhabdoid morphology, extensive necrosis, and a desmoplastic stroma. Overt anaplasia was absent. Immunohistochemically, the tumor was positive for cytokeratins; negative for PAX8, TTF1, CK20, p63, p40, CDX2, SOX10, AR and synaptophysin; p53 showed wild-type staining. Further evaluation revealed retained SMARCB1 and complete loss of SMARCA4 (BRG1) expression in tumor cells. Lack of thyroid lineage markers prompted molecular profiling, and NGS revealed Pathogenic mutations in exon 3 of NRAS gene and exon 11 of BRAF gene (non BRAF v600E), consistent with a follicular thyroid carcinoma profile. Thus, a diagnosis of anaplastic thyroid carcinoma with SMARCA4 loss; likely arising from dedifferentiation of a follicular thyroid carcinoma, was made. The patient is on palliative chemotherapy, with progressive disease. SMARCA4-deficient carcinomas occur at various sites, de novo or as dedifferentiated carcinomas; hitherto unreported in thyroid. This case highlights the importance of integrating morphology, immunohistochemistry, and molecular testing in aggressive thyroid-associated carcinomas, with implications for diagnosis, prognostication, and targeted therapy.

INTRODUCTION:A subset of prostate cancer progresses to aggressive state of metastatic castration-resistant prostate cancer (mCRPC), wherein multiple therapeutic options demonstrate limited success rates. In this observational study, we aimed to evaluate the efficacy, toxicity, and survival outcomes of (a) [225Ac]Ac-PSMA-617, (b) rechallenge [177Lu]Lu-PSMA-617, (c) cabazitaxel, and (d) oral metronomic cyclophosphamide treatments in postdocetaxel mCRPC patients with progressive disease following initial course of [177Lu]Lu-PSMA-617 or without previous [177Lu]Lu-PSMA-617 PRLT (PSMA-targeted radioligand therapy). METHODS:The study reviewed the medical records of mCRPC patients who had documented disease progression following treatment with androgen receptor pathway inhibitors and docetaxel. These patients had multiple therapeutic options and treated with [225Ac]Ac-PSMA-617(alpha based-PRLT) or rechallenge [177Lu]Lu-PSMA-617 or chemotherapy with cabazitaxel or metronomic cyclophosphamide. We stratified the latter group (chemotherapy) based on prior exposure to initial course of [177Lu]Lu-PSMA-617 as received and not received. We evaluated and analyzed the response outcomes from these therapies under five headings: (a) symptomatic response, (b) biochemical response, (c) functional and anatomical imaging response, (d) survival outcomes, and (e) toxicity profiles. RESULTS:A total 66 mCRPC patients were included and analyzed in this study. These patients were divided into two cohorts. Cohort 1 (n = 49 patients) received initial course of [177Lu]Lu-PSMA-617 and cohort 2 (n = 17 patients) not received initial course of [177Lu]Lu-PSMA-617. The patients were divided into arm A to F based upon treatment received as follows: Cohort 1- arm A (n = 15 patients) received [225Ac]Ac-PSMA-617, arm B (n = 18 patients) received rechallenge [177Lu]Lu-PSMA-617, arm C (n = 8 patients) received cabazitaxel, arm D (n = 8 patients) received metronomic cyclophosphamide. Cohort 2- arm E (n = 14 patients) cabazitaxel and arm F (n = 3 patients) metronomic cyclophosphamide. Patients in arm A showed favorable response outcomes in terms of symptomatic response evaluation and quality-of-life performance, biochemical and imaging response evaluation, with a PSA decline of > 50% and disease control rate (DCR) of 60% patients and 80% respectively. Patients treated with rechallenge [177Lu]Lu-PSMA-617 and chemotherapy also showed modest response rates. For toxicity profiles, arm A and arm B patients had mild and manageable toxicities, contrary to arm C, D, E, and F, wherein severe clinical and hematological toxicities were observed in a significant fraction of patients. Median progressive free survival (PFS) for the overall cohort (cohort 1 and 2) was 5 months (95% CI: 4-7 months), with no significant difference across treatment arms (p = 0.28). Median overall survival (OS) for entire cohort was 12 months (95% CI: 9-15 months) with significantly longer OS in arm A and E patients compared to other arms (p = 0.0358). CONCLUSION:Postdocetaxel mCRPC patients with progressive disease following initial course of [177Lu]Lu-PSMA-617 when treated with [225Ac]Ac-PSMA-617PRLT showed favorable and encouraging clinical, biochemical, and imaging response rates along with longer PFS and OS with minimal treatment-related toxicities. Rechallenge [177Lu]Lu-PSMA-617 and chemotherapy-based approaches also provided clinical benefit in selected patients, reflecting the range of salvage treatment strategies employed in real-world practice. Future large-sized, prospective randomized trials are needed to establish the efficacy of all these treatments particularly alpha-based PRLT in clinical practice of mCRPC patients.

PURPOSECarica papaya leaf extract (CPLE) is known to increase platelet counts (PCs) in certain infections.METHODSPatients were randomly assigned in a 2:1 ratio to the CPLE or placebo arm and continued treatment until the PC improved to 75,000 × 109/L or above, a platelet transfusion was required, or upto D+10. The primary outcome was to evaluate whether CPLE improves PC faster compared with placebo in a significant proportion of patients with a modified intention-to-treat protocol.RESULTSBetween March 2020 and October 2024, 219 patients were randomly assigned, of whom 198 patients (CPLE arm: 129; placebo arm: 69) were analyzed for outcomes. The primary end point with modified intention-to-treat analysis showed a statistically significant increase in PC to ≥75,000 × 109/L in a greater proportion of patients by D+4 compared with placebo (59% v 44%; P = .042). The primary outcome of increasing PC >75,000 × 109/L at D+4 was significantly improved by CPLE (83/129, 64% v 33/69, 48%; P = .034) compared with placebo as per protocol analysis. There was no grade 3 or grade 4 treatment-related adverse events associated with CPLE. About 43% of patients in the placebo arm versus 25% of patients in the CPLE arm needed dose reductions or delays in their subsequent chemotherapy treatment for patients with grade 2 chemotherapy-induced thrombocytopenia (CIT) at the baseline (P 0.033) and not significant in grade 3 CIT.CONCLUSIONCPLE is a potential therapeutic intervention to improve CIT faster and to a greater extent than placebo in this phase III randomized trial without any safety concerns. It could be potentially used as a secondary prophylaxis to maintain the chemotherapy intensity.

12008 Background: There is a lack of approved therapeutic options to ameliorate CIT in patients with solid tumors receiving chemotherapy. Carica papaya leaf extract (CPLE) is known to increase platelet counts (PC) in certain infections. Methods: The PACT study is a triple blinded randomized phase III study conducted in two academic centres in patients with solid tumors receiving chemotherapy and developing at least grade 2 or grade 3 CIT (platelet counts < 75,000 x 10^9/ liter and > 25,000 x 10^9/liter). Patients were randomized 2:1 to CPLE arm (capsule CPLE per oral 1100mg three times daily) or placebo arm ( capsule per oral three times daily), which was continued till PC improved to greater than > 75,000 x 10^9/ liter, requirement for platelet transfusions or D+10 post intervention. Baseline PC were graded as per the Common Terminology Criteria for Adverse Events (CTCAE) grades. The primary endpoint of the study was to evaluate whether CPLE improves PC significantly faster (as assessed on D+4 of intervention) and above 75,000 x 10e9 /L as compared to placebo (spontaneous recovery of platelets). To achieve 80% power to detect a difference between the group proportions of 0.25 (50% to 75%) with an alpha of 0.05, 219 patients were required (146 in CPLE group and 73 in placebo group), assuming 10% loss to follow-up rates. Results: Between March 2020 and October 2024, 219 patients were randomized, of whom 198 patients (CPLE arm: 129; placebo arm: 69) were analysed for outcomes. All the baseline parameters were equally distributed in both the arms (2:1) except the proportion of patients in the placebo and the experimental arms had equal number of patients with grade 3 thrombocytopenia (17/129 vs 17/69; p = 0.049). The most common chemotherapeutic regimens were oxaliplatin based (37%) and carboplatin based (27%). The primary outcome of increasing PC > 75,000 x 10^9/ liter at D+4 was significantly improved by CPLE (83/129, 64% vs 33/69, 48%; p = 0.034) as compared to placebo. This improvement was significantly quicker in subgroups including three weekly regimen vs weekly/biweekly, palliative intent vs. curative, > 2 cycles of chemotherapy (< = 2 cycles vs. > 2 cycles) and body surface area (BSA) < 1.6 vs. more. There were no grade 3 or grade 4 treatment related adverse events associated with CPLE. Conclusions: CPLE is the first therapeutic intervention that appears to improve grade 2 and grade 3 chemotherapy induced thrombocytopenia faster and to a greater extent than placebo in this phase III randomized trial. It should be used as a secondary prophylaxis to maintain the chemotherapy intesnity. There were no major safety concerns with the use of CPLE. Clinical trial information: CTRI/2019/08/020987 .

Pulmonary embolism (PE) is a significant cause of morbidity and mortality in cancer patients, yet its clinical presentation is often nonspecific, leading to potential overuse of CT pulmonary angiography (CTPA). This study aimed to determine the incidence of acute PE in a cohort of cancer patients referred for CTPA at a tertiary care cancer centre and to identify clinical and radiological risk factors that predict its presence. We conducted a retrospective observational study of 369 consecutive cancer patients who underwent CTPA for suspected PE between January 2015 and May 2019. Clinical, laboratory, and imaging data were collected from electronic medical records. CTPA scans were reviewed for the presence of acute PE and alternative diagnoses. Univariate and multivariate logistic regression analyses were performed to identify independent predictors of PE. The negative predictive value of D-dimer was also assessed. The incidence of acute PE was 21.4

e20029 Background: Tissue biopsy-derived DNA has long been the gold standard for tumor-specific genomic profiling. Similarly, genomic profiling using circulating tumor DNA (ctDNA) has been next evolving molecular companion for treatment decisions, monitoring, and escalation/de-escalation of therapy choices. In malignant pleural effusion (MPE), DNA extracted from pleural fluid cell blocks has traditionally served as the primary source for molecular testing to inform cancer treatment decisions but it fails to pass DNA isolation due to less cellular content. The ease of pleural fluid collection, its proximity to the tumor, and its utility for ongoing monitoring position it as a less invasive, practical alternative for lung cancer diagnostics. This approach holds promise for longitudinal monitoring and may reduce the need for repeat biopsies in precision oncology diagnostics. We investigated the potential of molecular testing using ctDNA obtained from pleural effusion cytology supernatants (PE-CCS) alternative to ctDNA from blood. Methods: We conducted a retrospective analysis of the genomic profiles of 15 lung adenocarcinoma patients with samples derived from both blood and malignant pleural effusion. Circulating tumor DNA (ctDNA) extracted from both pleural fluid and plasma was analyzed and compared for actionable alterations using next-generation sequencing (NGS) with the OncoIndx comprehensive demonic panel (CGP) assay. Results: Retrospectively,ctDNA was successfully isolated from both pleural fluid and peripheral blood of 15 lung cancer patients. Among the samples with successful isolation 67% (10/15) demonstrated concordance in actionable or targetable mutations (for genes such as EGFR:p.L858R, EGFR:p.S768I, TP53:p) between ctDNA derived from pleural fluid and peripheral blood. In contrast, 33% (5/15) exhibited actionable mutations detected (EGFR) in ctDNA from pleural fluid that were not identified in ctDNA from peripheral blood. In 50% of patients, variant allele frequency (VAF) (minimum highest VAF of 1% and maximum highest VAF 80%) was higher in pleural fluid than in peripheral blood. Interestingly, in one patient a resistance mutation (EGFR Amplification (13 copies) was detected in pleural fluid but not in peripheral blood. Conclusions: Proximal samples, like pleural fluid, are closer to the tumor site and thus better capture tumor-derived DNA, making them more reliable for diagnostics and therapeutic insights.Pleural ctDNA NGS offers diagnostic performance comparable to tumor biopsies and surpasses pleural cytology and plasma ctDNA in detecting oncogenic mutations in lung adenocarcinoma.

PURPOSEThyroid dyshormonogenesis, a form of congenital hypothyroidism, is characterized by defects in thyroid hormone synthesis genes, affecting both children and adults. However, the potential link between such genetic defects and the development of papillary thyroid cancer (PTC) remains unclear.METHODSWe conducted whole-exome sequencing on 100 (N = 100) tumor-normal paired and orphan tumor samples of PTC from Indian patients, characterizing both germline and somatic molecular alterations.RESULTSWe identified significant germline mutations in the DUOX2 gene (approximately 8.8%), commonly associated with congenital hypothyroidism and thyroid dyshormonogenesis, and found these mutations to correlate with poor prognosis in PTC. Additionally, hallmark somatic mutations were detected in genes such as BRAF (35.4%), KRAS (3.8%), HRAS (5.1%), and NRAS (17.7%), which are well-known drivers of PTC. Importantly, we identified a distinct molecular subtype termed independent of BRAF-RAS (iBR), characterized by nonhallmark alterations and associated with a higher recurrence rate and poorer recurrence-free survival in Indian patients with PTC, highlighting the clinical significance of these molecular insights in prognosis and treatment strategies.CONCLUSIONOur analysis of PTC among Indians revealed novel genetic alterations and molecular subtypes. We identified a germline mutation in the DUOX2 gene, associated with congenital hypothyroidism, as a potential risk factor of PTC. Additionally, we characterized distinct molecular subtypes, BRAF-RAS driven and iBR driven, and their clinical implications. These findings provide valuable insights into the genetic landscape of thyroid cancer in Indian patients and offer potential avenues for targeted therapies.

This prospective cohort study quantified the biological impact of treatment delay in oral squamous cell carcinoma (OSCC) through tumour kinetics. Between July 2020 and December 2023, 483 patients with treatment-naïve OSCC, Mumbai, underwent two pre-surgery cross-sectional imaging studies at least three weeks apart. Gross tumour volume (GTV) was measured to calculate weekly percentage growth and tumour volume doubling time (TVDT) using the Schwartz exponential model. The median interval between scans was 7.1 weeks (IQR, 5.9–9.4). Median GTV increased from 12.9 cm³ (IQR, 8.1–20.2) to 19.4 cm³ (IQR, 12.3–28.6), a 7.3% median weekly rise corresponding to a TVDT of 7.9 weeks. Tongue tumours grew fastest (9.6% per week; TVDT 6.2 weeks). Stage migration occurred in 30%, leading to more extensive resections in 28%. At 25 months’ median follow-up, 2-year overall survival (OS) and disease-specific survival were 67% and 73%, respectively. Patients with TVDT ≤8 weeks had lower OS (58% vs 74%, p=0.002). On multivariable analysis, TVDT ≤8 weeks, treatment delay >8 weeks, advanced T/N-category, and perineural invasion independently predicted worse outcomes. OSCC doubles in volume within 6–10 weeks, and tumour kinetics offer a quantifiable marker of aggressiveness that should inform scheduling and prognosis.

OBJECTIVES:Computer tomography (CT) measurements of cross-sectional area and density reflect muscle performance and function, but their use is limited in practice. We aimed to evaluate the association of CT-based skeletal muscle quality (qSMQ) with geriatric assessment (GA) and outcomes in older Indian patients with cancer. METHODS:Retrospective observational study in the geriatric oncology clinic in Mumbai, India. Patients aged ≥60 years with cancer who had undergone GA and had CT scan were included. To evaluate skeletal muscle quality, region of interest was drawn on bilateral paraspinal muscle at L3 vertebral level, one section above and below. RESULTS:Between June 2018 and November 2021, 277 patients were included. At a median follow-up of 23.8 (21.4-28.4) months, 174 deaths had occurred. Using the lower quartile as a cutoff to define poor and good qSMQ, the median overall survivals were 10.7 and 17.5 months in the patients with poor and good qSMQ, respectively (P = 0.124), which was significant after adjusting for body mass index (BMI), primary tumor, metastasis, and performance status (hazard ratio (HR): 1.53; 1.08-2.18, P = 0.017). The likelihood ratio test (LR-test) comparing the full model (qSMQ with nested model) with the nested model (age, sex, BMI, primary tumor, performance status) found that the addition of qSMQ was a significantly better fit (P = 0.015). DISCUSSION:The utilization of CT scans for older Indian patients with cancer is an effective and crucial means of evaluating skeletal muscle quality. It is closely associated with anthropometric measures, frailty, and overall survival (OS).

Microbial infections contribute to ~20% of malignancy. Plasma-derived cell-free DNA presents a promising avenue for non-invasive cancer diagnostics, capturing microbial signatures. We analyzed 261 plasma from 50 patients with lung adenocarcinoma by targeted and whole exome sequencing at 10,000 × and 340 × depth, respectively. Comparative analyses of Kraken 2 and IPD2 reveal substantial discrepancies, highlighting challenges in microbial DNA quantification and the need for stringent bioinformatics approaches to ensure accurate cancer microbiome profiling.

e16518 Background: The Phase-III Checkmate 9ER trial has established cabozantinib and nivolumab as an approved first-line treatment option in patients with metastatic clear-cell renal cell carcinoma (RCC). However, full-dose immunotherapy (IO) imposes significant financial burden in resource-limited settings. We aimed to evaluate the impact of low-dose IO with tyrosine kinase inhibitors (TKI) in our patients. Methods: This retrospective single-center analysis was done at our center from Jan 2019 to Dec 2024. Patients with advanced RCC planned for first-line systemic treatment were included. We assessed treatment efficacy [objective responses (ORR)], safety, pattern of treatment and impact on survival outcomes [progression-free (PFS) and overall survival (OS)] with the addition of low-dose IO (nivolumab 20mg or 40mg) in our patients. Results: Data of 67 patients was analyzed. Median age was 56 years (IQR, 48-63), 85.1% (n=57) were males and 86.6% (n=58) had an ECOG-PS of 0-1. Patients with clear-cell and non-clear cell histology were 64.2% (n=43) and 35.8% (n=24) respectively. Lung is the most common site of metastasis (55.2%, n=37). Among patients with clear-cell histology (IMDC risk details available in n=42/43), 23.8% (n=10/42), 57.1% (n=24/42), and 19.0% (n=8/42) had good, intermediate and poor IMDC risk respectively. First-line treatment with TKI and low-dose IO was given to 72.1% (n=31/43) and 62.5% (n=15/24) patients with a clear-cell and non-clear cell histology respectively, while TKI alone (sunitinib, pazopanib, cabozantinib) was given to 27.9% (n=12/43) and 37.5% (n=9/24) patients respectively. The ORR in patients with a clear- cell histology was 68.0% (n=17/25) with TKI and low-dose IO versus 50.0% (n=5/10) with TKI alone (p=0.319). It was 50.0% (n=6/12) with TKI and low-dose IO versus 0% (n=0/7) with TKI alone (p=0.024) in patients with a non-clear histology. The median follow-up was 11.4 months (95%CI, 8.0-14.8). The median PFS in patients with clear-cell histology was ‘not reached’ with TKI and low-dose IO versus 9.9 months (95%CI, 1.6-18.2, p=0.116) with TKI alone. It was 6.7 months (95%CI, 0.7-12.7) versus 6.5 months (95%CI, 0.0-16.4, p=0.303) in non-clear histology. The median OS was ‘not reached’ in patients with a clear-cell histology, whereas, it was 12.4 months (95%CI, not reached) with TKI and low-dose IO and 14.4 months (95%CI, 8.0-20.8, p=0.890) with TKI alone in the non-clear histology. Conclusions: Limited follow-up showed higher response rates, and a trend towards improved survival with the addition of low-dose nivolumab to TKI in patients with clear-cell RCC. Keyword: Low dose nivolumab, Clear-cell renal cell carcinoma, Tyrosine kinase inhibitors.

e18025 Background: HNSCC imparts rising incidence and mortality rate worldwide, due to lack of information regarding spatial and temporal heterogeneity of the tumors. Nearly 50 to 60% of advanced node positive HNSCC are known to develop platinum resistance during the course of treatment. Beyond this, Metronomic Chemotherapy (MC; erlotinib 150mg daily, celecoxib 200mg BD daily, methotrexate 9mg/m2 every week) has shown promising effect by impacting the PFS and OS in the palliative setting. Nevertheless, only nearly 50% of these patients get the benefit of MC, which could be attributed to the underlying biology. At this stage, stratifying patients using the tumors’ mutational landscape would be more beneficial. This pilot study was aimed to understand the prognostic implications of adding liquid biopsy to solid tumor profiling in HNSCC. Methods: We adopted Whole Exome Sequencing of Tumor (Solid) and LiQuid biopsy (SoliQ) at the time of diagnosis in 10 HNSCC patients, with advanced stage recurrent/metastatic head and neck cancers, platinum resistant. The NGS libraries were generated as per standard procedures for illumina sequencing. The tumors were sequenced to a coverage depth of 250X, while the plasma cfDNA was sequenced to a coverage depth of 500X. Results: Broad genomic landscape of more than 230 pathogenic genes were unveiled, among which the frequently mutated genes were EGFR, CCND1, PIK3CA, NOTCH1, TP53, CDKN2A, KMT2A, FBXW7 and EP300 . Major findings included: a) 40% concordance in mutations identified between tumor tissue and liquid biopsy at the baseline b) those patients who had positive cfDNA/ctDNA fraction at baseline as measured from mutant allelic fraction, had a poor PFS (cfDNA positive PFS- 2.28 months (95% CI 1.733 -NA) and in cfDNA negative- 4.63 months (95% CI 0.967 -5.27). P= 0.06) and OS (cfDNA positive OS- 7.77 months (95% CI 3.63 -8.1) and in cfDNA negative- 4.92 months (95%CI 1.73 -NA). P= 0.0082) as compared those patients who had negative ctDNA fraction/no clinically relevant or somatic alterations identified in plasma cfDNA. Conclusions: This pilot study is the first of its kind to demonstrate the clinical utility of combining liquid biopsy profiling with tissue biopsy at baseline in HNSCC, using whole exome sequencing approach. Prospective studies on larger number of patients may help in establishing its role as part of the initial diagnostic work-up to be included in future guidelines/standard-of-care practice.

OBJECTIVES:Metronomic therapy is one of the modalities used to treat OSCC. The present study is the first comprehensive analysis evaluating the potential of circulating endothelial cells (CECs) and their progenitors (CEPs) as prognostic biomarkers in OfSCC patients receiving metronomic therapy. MATERIAL AND METHODS:91 patients were included in the study group. ORR was 42.9 %, while the median OS and PFS were 6.67 months and 4.3 months, respectively. The counts of CECs and CEPs were enumerated by flow cytometry at baseline and follow-up (8, 30, 60, and 90 days after metronomic therapy). RESULTS:We correlated the baseline and reduction of CECs after treatment with clinical response, PFS, and OS. Patients with high CEP levels at day 60 showed longer PFS, while patients with low CEC levels at day 30 had better PFS and OS. Change in CEC levels after 8 and 30 days was also correlated with PFS and OS, respectively. The change in CECs 8 days after metronomic therapy as a prognostic biomarker was further validated by multivariate Cox regression. A decline in CECs after 8 days had a favourable impact on OS, while none of the CEP measurements at any time point were statistically associated with OS or PFS. CONCLUSION:The reduction of CECs after treatment might serve as a prognostic biomarker, whereas the baseline CEC counts as a predictive or prognostic factor in patients treated with metronomic therapy. The correlation between clinical response and survival further supports the biological relevance of these CECs and CEPs as prognostic biomarkers.

e14012 Background: ctDNA based liquid biopsies have transformed cancer care by enabling the detection of actionable mutations, monitoring progression, therapy response, and prognosis. Cerebrospinal (CSF) fluid-based liquid biopsies (CSF-LBx) for CtDNA and CTC may offer a promising alternative, providing critical insights into the molecular landscape of brain metastases. We demonstrate, CSF-LBx with precise detection of ctDNA, having clinically significant markers especially metastasis settings, including leptomeningeal mets. In addition we paired samples having both CSF and blood for ctDNA. Further we captured true single circulating tumor cells (sCTCs), CTCs in paired CSF and in peripheral blood samples. Methods: In a retrospective study, we isolated both ctDNA and CTCs in 11 paired blood and CSF samples having brain metastasis. Patients were presented with, lung with brain and liver mets, multifocal glioblastoma, lobular breast, relapsed cerebellar medulloblastoma, NSCLC, Ca Ovary, lung with medulloblastoma, low grade glioma, etc. Further, CTCs were isolated using OncoDiscover CDSCO India approved platform having anti EpCAM antibody, and sCTCs were captured and released using OncoIndx Ikon platform. Further, OncoIndx comprehensive NGS assay was performed with 1080 genes. Results: In a retrospective we evaluated 11 brain metastatic patients who had paired samples having both CSF and blood. 6 patients had 2 or more sample points. A total of 30 CTCs were isolated from CSF, compared to 42 CTCs isolated from blood. Notably, two CTC clusters were identified in CSF, compared to 10 clusters observed in blood. While ctDNA was isolated from both CSF and blood. NCCN based actionable mutations were identified in 45% (n = 5) of CSF ctDNA samples and 36.36% (n = 4) of blood ctDNA samples. Treatment resistance mutations in the EGFR, ERBB2, PIK3CA, and CDKN2A/2B genes were observed in 4 CSF samples, while sensitive mutations were detected in both CSF and blood. CSF-ctDNA revealed more actionable mutations, including both sensitive and resistance mutations, compared to blood alone in patients in leptomeningeal metastasis. The absence of resistance drivers in blood underscores the importance of sampling more proximally to the metastatic site to improve survival outcomes. Conclusions: CSF has great potential to analyse, both ctDNA and CTC and sCTCs enrichment for molecular profiling. CSF ctDNA exhibited NCCN based actionable mutations, in particular, in cases such as glioblastoma, where tissue biopsies are often not feasible, and blood-based diagnostics face limitations due to DNA sensitivity. Further studies to establish sensitivity and specificity is desired.

6036 Background: Head and Neck cancer (HNC) is among the diverse group of malignancies affecting the head and neck region including the oral cavity. Being the most prevalent malignancy in Southeast Asia, it has a high mortality rate. Despite the advancement in treatment, 5 years survival rate for HNC remains below 50%, and the majority of Pts receiving frontline therapy experience locoregional or incurable metastatic relapse. Immune checkpoint inhibitors (ICI) are recommended for relapsed patients, but only 20% of patients show measurable response. Currently, no predictive biomarkers are available to predict ICI response and there is an urgent need for genomic markers to predict ICI outcomes. Here we report comprehensive genomic profiling (CGP) of advanced HNC patients receiving ICI. Methods: ctDNA from 69 advanced HNC patients receiving combinational immune-chemotherapy were serially profiled at the baseline (BL) and post-treatment (Tx) by targeted, hybridization-based CGP using OncoIndx comprehensive gene panel (CGP) comprising 1080 genes. The ctDNA differential features at BL and post-Tx as well as among responders (R) and non-responders (NR) were correlated with Progression-free survival (PFS) and Overall survival (OS) using Kaplan-Meier statistics and multivariate analysis. Results: Among total patients, 58% (40/69) were responders (R) while the remaining were non-responders (NR). At the population level, HRR pathway tumor suppressors and epigenetic modifiers were the most frequent pathogenic variants. At BL, the NR population was enriched with oncogenic gene mutations compared to the R population. TP53 and BRCA pathway mutations (mTP53 + BRCA) showed a strong association with progression-free survival (PFS) and overall survival (OS). Pts with cooccurring mTP53 + BRCA had significantly lower PFS (median PFS: 2.77 months for mTP53 + BRCA pathway vs 9.1 months for wt TP53 + BRCA pathway. P=<0.0001, HR=3.2-11.6) and OS (median OS: 4.67 months for mTP53 + BRCA pathway vs 12.63 months for wtTP53 + BRCA pathway. P=<0.0001, HR = 11.18-55.27). NOTCH 1 or 2 variants were enriched in R population, with a beneficial effect on survival outcomes. Elevated ctDNA alterations and Tumor fraction (TF) concentrated in the NR population disproportionately contained subclonal potential drivers of immunotherapy resistance including NF1, STAT5 B, and STK11 mutations, and were associated with short survival. Univariate and multivariate analysis suggested that ctDNA mutations, TF, and high mutational heterogeneity emerged as risk factors for shorter PFS and OS. In contrast, total Indel burden and NOTCH mutations had beneficial effects on PFS and OS. Conclusions: Minimally invasive plasma ctDNA CGP showed heterogenous actionable mutations at BL and post Tx and identified immunotherapy resistance conferring genomic markers for stratifying potential responders for immunotherapy guidance.

We thank Das et al.[1] for the invaluable insights on our molecular tumor board article, "NUT-midline carcinoma of the lung with rare BRD3–NUTM1 fusion."[2] Das et al.[1] highlighted the immunohistochemical (IHC) phenotypes of nuclear protein in testis (NUT) carcinoma. In our case presentation, IHC positivity of NUT confirmed the histopathologic diagnosis of NUT midline carcinoma of the lung. NUT expression is a hallmark of NUT carcinoma.[3,4] P40 is highly sensitive and specific for squamous cell carcinoma. However, its presence alone does not conclusively confirm squamous cell carcinoma (SCC), like other cancers, may also express P40. In the case described, the tumor cells were positive for both P40 and NUT. While P40 positivity might suggest squamous differentiation, the concomitant strong positivity for NUT is more indicative of NUT carcinoma over squamous cell carcinoma as the final diagnosis. Typically, NUT carcinomas usually occur in the midline structures of the body such as the head, neck, and mediastinum; however, they can also manifest in the non-midline areas. Recognition of NUT carcinoma in the non-midline areas is crucial for timely diagnosis and treatment. The authors' insight is quite compelling in emphasizing the distinctive features of the primary histomorphological examination to identify NUT carcinomas. They also highlighted how identification is more common when it occurs in the non-midline regions. The main histopathologic indications of NUT carcinoma are undifferentiated or poorly differentiated histology and atypical nuclear morphology. In addition, high mitotic index, diffuse growth pattern, elevated Ki-67 proliferation index, and absence of squamous differentiation markers (e.g. CK5/6, p63) in cases with squamous differentiation give strong attestation of NUT carcinoma.[3,5] Similarly, a conjecture of NUT carcinoma should be raised in non-midline regions when there are atypical clinical presentations, rapid tumor growth, characteristic histologic features, young age of onset, failure to respond to standard treatments, or evidence of metastasis. The confirmation of NUT carcinoma is reinforced by IHC staining and positivity for NUT protein, or next-generation sequencing (NGS). We strongly concur with the use of NGS, as it confirms the presence of NUT fusion and opens an avenue for the discovery of new therapeutic targets, deepening our understanding of the complex and aggressive biology exhibited by these tumors. However, NUT carcinoma poses a significant clinical challenge due to its status as an orphan disease, lacking established treatment protocols, and typically presenting a bleak prognosis. Das et al.[1] have provided a holistic overview of therapeutic options for these aggressive cancers. The available sparse information also indicates these tumors may be amenable to treatment with immune checkpoint inhibitors, warranting further investigation.[6] To summarize, an accurate diagnosis of NUT carcinoma requires a comprehensive evaluation by a multidisciplinary team, including pathologists who could employ clinicopathologic correlation for the advanced interpretation of the cases. NUT carcinoma remains a unique challenge in the landscape of solid cancers, with limited treatment options and a generally dismal outlook, making the search for effective therapies for the management of this rare and aggressive cancer more important than ever before. Financial support and sponsorship Nil. Conflicts of interest Kumar Prabhash is a member of the editorial board of Cancer Research, Statistics and Treatment. As such, he may have had access to information and/or participated in decisions that could be perceived as influencing the publication of this manuscript. However, he recused himself from the peer review, editorial, and decision-making process for this manuscript, to ensure that the content is objective and unbiased.