Anal Squamous Cell Carcinoma Research Articles

A Population-Level Validation of the New 9th Edition of the American Joint Commission on Cancer Staging System for Anal Squamous Cell Carcinoma.

The staging system for anal squamous cell carcinoma (ASCC) was recently revised, downstaging selected node-positive patients and upstaging some with larger tumors. We aimed to validate this staging system using a population-based cohort. The Surveillance, Epidemiology, and End Results database was analyzed to identify adult ASCC patients. Patients were staged according to the American Joint Committee on Cancer (AJCC) 8th and 9th edition systems. Survival probabilities were estimated using Kaplan-Meier curves. Cox regression models were utilized to estimate the effect of stage on overall (OS) and cancer-specific survival (CSS). A total of 2117 patients were identified and staged based on the two AJCC classifications. At 24 months when comparing stage IIB versus stage IIIA, the 8th edition revealed an improved OS (79% vs. 88%) and CSS (84% vs. 91%) for stage IIIA disease, while the 9th edition restored the hierarchical OS (IIB 88% vs. IIIA 78%) and CSS (91% vs. 82%) order. The hierarchical increase of the OS HRs, and nearly all CSS HRs, across disease stages validated the updated edition of the AJCC classification. Although this change may not have significant implication on the management of ASCC, it does provide better prognostication.

Utility of SATB2 and MOC-31 Immunostains to Distinguish Between Poorly Differentiated Rectal Adenocarcinoma and Anal Squamous Cell Carcinoma.

Colorectal adenocarcinoma and squamous cell carcinoma (SCC) can arise in the anorectum and present a significant diagnostic challenge when poorly differentiated. Accurate diagnosis can significantly influence management, as the treatments for these conditions involve distinct neoadjuvant chemoradiotherapy regimens. MOC-31 and SATB2 have been utilized as specific markers of glandular differentiation and colorectal origin, respectively, but studies have shown that they may be positive in squamous cell carcinoma of other sites. This raises the concern that MOC-31 and SATB2 may be positive in squamous cell carcinoma of the anorectum, and overreliance on these stains may be a potential diagnostic pitfall in differentiating rectal poorly differentiated adenocarcinoma (PDA) from anal nonkeratinizing SCC. We identified biopsies from 10 rectal PDA and 17 anorectal nonkeratinizing SCC cases and stained them for MOC-31 and SATB2. We found that MOC-31 was highly sensitive, being positive in 10/10 cases of rectal PDA, but not specific, as it was also positive in 11/17 SCC cases. In contrast, SATB2 was both sensitive, with positive staining in 10/10 rectal PDA cases, and specific, with negative staining in 17/17 SCC cases. This includes equivocal staining in 4 of these negative SCC cases. MOC-31 had a sensitivity of 100% and specificity of 35.3%, while SATB2 had a sensitivity of 100% and specificity of 100%. Unlike squamous mucosa of the head and neck, and esophagus, SCC of the anus does not frequently stain positively for SATB2. These data suggest that SATB2 is a reliable marker in distinguishing rectal PDA from anorectal nonkeratinizing SCC, whereas MOC-31 is commonly positive in SCC of the anus. It is also important to note that equivocal SATB2 staining may be seen in SCC.

Prognostic implications of HIF-1α expression in anal squamous cell carcinoma treated with intensity-modulated radiotherapy (IMRT)

BackgroundHypoxia-inducible factor-1α (HIF-1α) is a crucial transcription factor activated under hypoxic conditions, known to regulate genes associated with tumor survival, progression, and response to therapy. This study aimed to evaluate the prognostic significance of HIF-1α expression in patients with anal squamous cell carcinoma (ASCC) undergoing chemoradiation therapy. MethodsWe conducted a retrospective analysis of 28 ASCC patients treated with intensity-modulated radiotherapy (IMRT) at our center from 2009 to 2022. HIF-1α expression was assessed via immunohistochemistry on formalin-fixed paraffin-embedded tissue specimens. Quantitative analysis of HIF-1α expression was performed, and its relationship with clinical outcomes, including disease-free survival (DFS), locoregional relapse-free survival (LRRFS), and overall survival (OS), was examined using Cox regression models. Furthermore, ASCC tissue specimens from 17 patients were analyzed for potential PIK3CA mutations using Sanger sequencing. ResultsHigh HIF-1α expression was significantly associated with poorer DFS (p = 0.005), LRRFS (p = 0.012), and OS (p = 0.009). HIF1α expression was marginally significantly higher in males compared to females (p = 0.056) while there was no significant difference found based on tumor stage or p16 status. However, a positive correlation was identified between BMI and HIF-1α levels (Pearson correlation r = 0.5, p = 0.0084), suggesting a link between metabolic status and tumor hypoxia. Only one patient exhibited a PIK3CA mutation, preventing a reliable assessment of its correlation with HIF-1α expression. ConclusionOur findings underscore the importance of HIF-1α as a potential biomarker for predicting survival outcomes in ASCC patients treated with chemoradiation. The association between higher BMI and increased HIF-1α expression may provide insights into the interplay between metabolic health and tumor biology in ASCC. Further studies with larger cohorts are needed to validate these findings and explore targeted therapies focusing on HIF-1α modulation.

94P A one-tube multiplex methylation-specific droplet digital PCR assay for identification of ctDNA biomarkers in anal squamous cell carcinoma

94P A one-tube multiplex methylation-specific droplet digital PCR assay for identification of ctDNA biomarkers in anal squamous cell carcinoma

108P Assessing molecular characteristics in a large cohort of anal squamous cell carcinoma patients

108P Assessing molecular characteristics in a large cohort of anal squamous cell carcinoma patients

Evaluating pre-consult patient education videos for patients with newly-diagnosed anal squamous cell carcinoma: Impact on patient comprehension, satisfaction and distress

We hypothesized that pre-consult patient education videos can improve patient understanding about their diagnosis, lead to high satisfaction and low distress. In this pilot study, we developed a patient education video curriculum for patients with newly-diagnosed anal cancer. Comprehension of key content was evaluated by comparing pre- and post-test scores. Patient satisfaction scores were collected. Patient distress scores (0–10) were collected at the beginning of their consult visit prior to seeing the physician. We found that patient education videos prior to consult improved patient understanding, resulted in high patient satisfaction, and low patient distress at the time of consult.

Electron beam radiotherapy for the management of squamous cell carcinoma of the anal margin.

Squamous cell carcinoma of the anal margin (SCCAM) is an uncommon lesion that comprises one-third to a quarter of all anal squamous cell carcinoma. Treatment involves surgery or exclusive radiotherapy for small tumours, whereas the preferred treatment for larger tumours is chemoradiotherapy. In our department, selected patients with SCCAM are treated with electron beam radiotherapy using one perineal field. The present study evaluates this strategy. All consecutive patients with SCCAM and treated with electron beam radiotherapy from 2012 to 2022 were included. Data were retrospectively extracted from the medical records and analysed descriptively. Local control (LC) and overall survival (OS) were analysed using Kaplan-Meier statistics. Forty patients were evaluated. Primary radiotherapy was delivered in 35 (87.5%) patients. Five (12.5%) patients had postoperative radiotherapy. Median prescription dose was 60.0 (range 45.0-60.2) Gy in 28 (range 10-30) fractions delivered with 8 (range 4-18) MeV using a standard circular aperture and bolus. At a median follow-up of 73 (range 9-135) months, 7 (17.5%) patients were diagnosed with local recurrences. The 5-year LC rate was 84.3% (95% CI: 71.4%-97.2%). Analysis of LC according to T-stage revealed a 5-year LC of 100% (95% CI: 100%-100%) in T1 tumours compared to 57.0% (95% CI: 27.4%-86.6%) in T2 tumours (p < 0.001). 5-year OS was 91.6% (95% CI: 83.0%-100%). Late grade 3 toxicity included ulceration in the skin and subcutis in 2 (5.0%) patients. Electron beam radiotherapy enables the delivery of 'eye-guided' radiotherapy directly to the tumour. LC is good in patients with T1 tumours. Patients with T2 tumours have less satisfactory LC and should be treated with chemoradiotherapy. Electron beam radiotherapy enables the delivery of "eye-guided" RT directly to the tumour. LC is excellent in patients with T1 tumours. Patients with T2 tumours have less satisfactory LC and should be treated with chemoradiotherapy.

Comparison of the TNM9th and 8th editions for localized and locally advanced anal squamous cell carcinoma treated nonsurgically and proposal of a new stage grouping system.

To compare the survival discrimination of the TNM9th and 8th editions for localized and locally advanced anal squamous cell carcinoma (ASCC) treated nonsurgically and suggest a simple revised staging system with data from the Surveillance, Epidemiology, and End Results (SEER) database. Overall survival (OS) was the primary endpoint. Survival comparisons between the T and N stages and the different staging systems were performed using the Kaplan-Meier method and log-rank test, followed by correlation analysis and variable importance analysis (VIA). Additionally, multivariate analysis was employed to identify significant predictors, which were further visualized using a nomogram. Finally, calibration curve, C-index, and decision curve analysis (DCA) were applied to assess the performance of the different staging systems. A total of 5384 patients with ASCC were analyzed, revealing superior discrimination OS by the TNM9th edition compared to that by the TNM8th edition. Multivariate analysis identified the T and N stages as significant OS predictors (all p < 0.001). However, ambiguity persisted in stage III subgroups within the TNM9th edition, showing OS times of 102 months for stage IIIA disease, 88 months for stage IIIB disease, and 128 months for stage IIIC disease (all p > 0.05). Correlation analysis demonstrated an increased correlation for the T stage between the TNM8th and 9th editions (ρ value from 0.7 to 0.89), while the N stage correlation decreased (ρ value from 0.84 to 0.56). VIA and the prognostic nomogram highlighted the greater importance of the T stage over the N stage. Based on these findings, a new staging system was developed, and its clinical utility was confirmed through calibration curves, C-index values (from 0.598 to 0.604), and DCAs. Our new staging system exhibited slightly better prognostic value compared to the TNM9th staging systems for nonmetastatic ASCC and warrants further validation.

71973 - Short-term morbidity and mortality following surgical treatment of anal squamous cell carcinoma in Sweden – a national multicenter study

71973 - Short-term morbidity and mortality following surgical treatment of anal squamous cell carcinoma in Sweden – a national multicenter study

Transcriptome and microbiome-immune changes across preinvasive and invasive anal cancer lesions.

Anal squamous cell carcinoma (ASCC) is a rare gastrointestinal malignancy linked to high-risk Human papillomavirus (HPV) infection, which develops from precursor lesions like Low-Grade Squamous Intraepithelial Lesions (LGSIL) and High-Grade Squamous Intraepithelial Lesions (HGSIL). ASCC incidence varies across populations, posing increased risk for People Living with HIV (PLWH). Our investigation focused on transcriptomic and metatranscriptomic changes from Squamous Intraepithelial Lesions (SILs) to ASCC. Metatranscriptomic analysis highlighted specific bacterial species (e.g., Fusobacterium nucleatum, Bacteroides fragilis) more prevalent in ASCC than precancerous lesions. These species correlated with gene encoding enzymes (Acca, glyQ, eno, pgk, por) and oncoproteins (FadA, dnaK), presenting potential diagnostic or treatment markers. Unsupervised transcriptome analysis identified distinct sample clusters reflecting histological diagnosis, immune infiltrate, HIV/HPV status, and pathway activities, recapitulating anal cancer progression's natural history. Our study unveiled molecular mechanisms in anal cancer progression, aiding in stratifying HGSIL cases based on low- or high-risk progression to malignancy.

Chemoradiotherapy versus radiotherapy alone in the management of early-stage anal squamous cell carcinoma: A comparative analysis of the French cohort FFCD-ANABASE

IntroductionEarly-stage anal squamous cell carcinomas (ASCC) are usually treated with chemoradiotherapy (CRT), with good outcomes. Radiotherapy (RT) alone might be sufficient while reducing toxicity. MethodsPatients included in the French prospective FFCD-ANABASE and treated for T1–2N0 ASCC between 2015/01 and 2020/04 were divided into CRT and RT groups. Clinical outcomes and toxicity were reported. Propensity score matching was conducted for 105 pairs of patients. Results440 patients were analyzed: 261 (59.3 %) in the CRT group and 179 (40.7 %) in the RT group. The median follow-up was 35.7 months. Patients receiving CRT were younger, had better Performance Status (PS) and larger tumors. No statistical difference was observed for 3-year Disease-free survival (85.3 % vs 83 %, p = 0.28), Overall survival (89.6 % vs 94.8 %, p = 0.69) and Colostomy-free survival (84.5 % vs 87.2 %, p = 0.84) between CRT and RT groups, respectively. Propensity score-matched analysis confirmed these findings. Treatment interruptions were significantly more frequent in the CRT group (36.3 % vs 21.9 %, p = 0.0013), resulting in an Overall Treatment Time (OTT) extended by 7 days. Grade 3 CTCAE v4.0 toxicities were more prevalent in the CRT group (46 % vs 19 %, p < 0.001). ConclusionAdding chemotherapy to radiotherapy did not significantly improve outcomes for T1–2N0 ASCC in our study, but increased toxicity and OTT.

Prognostic and predictive role of YKL-40 in anal squamous cell carcinoma: a serological and tissue-based analysis in a multicentric cohort.

Anal squamous cell carcinoma (ASC) is a rare gastrointestinal malignancy showing an increased incidence over the past decades. YKL-40 is an immune modulator and pro-angiogenetic factor that showed a promising prognostic and predictive potential in several malignancies, but limited data are available for ASC. This study aims to provide an extensive evaluation of the prognostic and predictive role of YKL-40 in a multicenter cohort of ASC patients. We retrospectively retrieved 72 consecutive cases of ASC diagnosed between February 2011 and March 2021. Both serum and tissue protein expression of YKL-40 were assessed, the latter in ASC tumor cells and peritumor immune cells. Increased YKL-40 serum levels at the time of diagnosis were associated with older age (p = 0.035), presence of cardiovascular/metabolic comorbidities (p = 0.007), and death for any cause (p = 0.011). In addition, high serum levels of YKL-40 were associated with a poor prognosis (HR: 2.82, 95% CI: 1.01-7.84; p = 0.047). Protein expression of YKL-40 in ASC tumor cells was significantly associated with low tumor grade (p = 0.031), while the increased expression in peritumor immune cells was associated with a worse response of patients to chemoradiotherapy (p = 0.007). However, YKL-40 protein expression in ASC tumor cells or peritumor immune cells did not significantly impact patient overall survival. In conclusion, YKL-40 resulted a relevant prognostic (serum level) and predictive (tissue protein expression in peritumor immune cells) biomarker and can considerably improve ASC patient clinical management.

A Population-Based and Propensity Score-Matched Investigation of the Occurrence, Management, and Prognosis of Anal Mucinous Adenocarcinoma Patients

Introduction: Anal mucinous adenocarcinoma (AMAC) is an extremely rare form of anal cancer. Our objective was to examine the incidence, management, and prognostic factors of AMAC. Methods: We analyzed age-adjusted incidence (AAI) rates over time and compared the prognosis of AMAC with anal squamous cell carcinoma (ASCC) and adenocarcinoma (AAC) using propensity score matching and Kaplan-Meier analysis. Patients were classified based on summary stage and treatments to determine cancer-specific survival. Results: AAI of AMAC fluctuated within a narrow range (0.082–0.237 per million person-years) from 2000 to 2018. AMAC had a slight non-significant trend of worse prognosis than ASCC (p = 0.348) and a better prognosis than AAC (p < 0.01). Females made up a larger proportion of patients diagnosed with the distant disease (p < 0.05) and unmarried (p < 0.05) and somewhat less probably to need surgical removal (p < 0.01) and radiotherapy (p < 0.01). Elderly patients have lower rates of survival (p < 0.05). Localized stage was associated with better prognosis (p < 0.05). Surgery was associated with a tendency toward better survival (p = 0.095). Conclusions: AMAC exhibits a low incidence yet favorable prognosis compared to typical AAC and slightly worse compared to ASCC. Elderly age is associated with poorer prognosis, while localized stage indicates better prognosis. Surgery demonstrates a trend toward improved survival.

HPV status and immunohistochemical analysis of p16, p53 and PD‑L1 expression as prognostic biomarkers in patients with squamous cell anal cancer receiving definitive radiotherapy/chemoradiotherapy.

Anal squamous cell carcinoma (SCC) treated with definitive radiotherapy (RT)/chemoradiotherapy (CRT) has shown high success rates, yet challenges such as treatment resistance and recurrence persist. The present study aimed to investigate the associations between immunohistochemical (IHC) evaluation, treatment response and prognosis in anal SCC. A retrospective cohort analysis included 42 patients with anal SCC treated at a single institution between 2006 and 2022. Human papillomavirus (HPV) status was determined, and the IHC analysis of p16, p53 and PD-L1 expression was conducted using formalin-fixed, paraffin-embedded biopsies. A complete response to RT/CRT was observed in 71.4% of patients. Recurrence occurred in 38.1% of cases, of which 7.1% had local-regional recurrence (LRR), 14.3% had distant recurrence (DR), and 16.7% had both LRR and DR. HPV positivity (71.4%) was significantly associated with p16 positivity. Lack of complete response was associated with HPV-negative status, p16-negative status, increased recurrence and DR. In addition, recurrence was significantly associated with p53-positive status, and p53 positivity was significantly associated with increased LRR. PD-L1 positivity, defined as a combined positive score (CPS) ≥1% was found in 73.8% of the patients, and exhibited significant associations with HPV positivity and p16 positivity. PD-L1 CPS ≥ 1% was also associated with an increased LRR. Univariate analysis revealed that age <65 years, a complete response and HPV positivity were associated with increased 5-year overall survival (OS), while a complete response, HPV positivity and p53-negative status were associated with increased 5-year disease-free survival (DFS). Multivariate analysis identified that age <65 years and HPV positivity are independent prognostic factors for 5-year OS, and a complete response and p53-negative status are independent prognostic factors for 5-year DFS. In conclusion, these findings suggust that the identification of HPV status and poor prognostic biomarkers at diagnosis may be used to guide personalized treatment strategies, with the combination of immunotherapy with standard CRT potentially providing improved outcomes.

Immunological Checkpoint Blockade in Anal Squamous Cell Carcinoma: Dramatic Responses Tempered By Frequent Resistance.

Squamous cell carcinoma of the anus (SCCA) is an HPV-associated malignancy that has limited treatment options. Immunotherapy has expanded these options and here we review current and emerging immunotherapeutic approaches. Multiple studies of single-agent anti-PD1/PD-L1 immunotherapy have demonstrated a modest response rate of approximately 10% to 15%. While a minority of patients (~5%) with SCCA experience durable complete responses, most advanced SCCAs are resistant to anti-PD1/PD-L1 monotherapy. Given the need for more broadly effective immunotherapies, novel strategies, such as adaptive cell therapies and therapeutic vaccination, are being explored. To reduce the recurrence risk of localized high-risk SCCA, strategies combining immunotherapy with chemoradiation are also being investigated. While a small subset of patients with SCCA have prolonged responses to PD1-directed immunotherapy, the majority do not derive clinical benefit, and new immunotherapeutic strategies are needed. Better understanding of the immune microenvironment and predictive biomarkers could accelerate therapeutic advances.

Efficacy and safety of nivolumab in pretreated patients with metastatic squamous cell carcinoma of anus: A real-world experience.

Efficacy and safety of nivolumab in pretreated patients with metastatic squamous cell carcinoma of anus: A real-world experience.

233P 3-year outcome of radical chemoradiotherapy for anal squamous cell carcinoma (ASCC) using intensity-modulated radiation therapy (IMRT) protocol at Southend Hospital

233P 3-year outcome of radical chemoradiotherapy for anal squamous cell carcinoma (ASCC) using intensity-modulated radiation therapy (IMRT) protocol at Southend Hospital

Role of dynamic ctDNA monitoring in cervical and anal epidermoid carcinomas under curative chemoradiation.

3141 Background: Cervical and anal canal squamous cell carcinoma (SSC) are a significant health problem in underdevelopment countries. Definitive chemoradiation (CRT) is the standard-of-care (SOC) approach for curative treatment in locally advanced disease. Due to the common substantial local inflammation during CRT, the conventional clinical image cannot identify non-responders early. In this scenario, the evaluation of circulating tumor DNA (ctDNA) is a promising tool for real-time tumor response monitoring. Methods: We performed a prospective multicentric cohort study of patients treated between 2020 and 2023 in tertiary oncologic centers in Brazil to evaluate the role of ctDNA dynamic monitoring in epidermoid cervical (CC) and anal cancer (AC) T1-4, N0-1, M0 by AJCC 8th edition and candidates to complete curative CRT. The cDNA was assessed by Signatera test at D1, D29, immediately post-treatment, 8 weeks (w) post-CRT, 24w post-CRT, every 6 months (m) in the first 1-2 years(y), and yearly at 3-5y of follow-up (FUP). The primary endpoint was to estimate the correlation of ctDNA with a tumoral response assessed by conventional routine image and clinical evaluation at 8w. Secondary endpoints included a correlation between ctDNA results at different time points with progression-free survival (PFS) and overall survival (OS). The predictive potential of the biomarker was evaluated using receiving operating characteristic (ROC) curve analysis. Results: We included 33 patients, and 27 were evaluable with ctDNA, with a median FUP of 10m. The majority were female (n=23, 85.1%), and 3 (11%) were HIV-positive(+). Most patients presented with positive nodes and stage III disease (n=18, 66.6%). In the AC group (n=15), the majority received CRT with capecitabine and cisplatin (n=12, 55.5%); in the CC group (n=12), all pts received cisplatin. All pts tested expressed ctDNA+ before treatment. At 8w, images had a sensitivity of 42.8% and specificity of 100% for disease progression (area under the curve [AUC] 0.714), while ctDNA yielded a sensitivity of 85.7% and specificity of 89.4% (AUC 0.875). The ctDNA+ immediately after CRT ended (32%) was consistent with ctDNA+ at 8w (30.7%) and 24w (30%). Pts with ctDNA+ immediately post CRT have a higher risk of disease progression with PFS of 8.2m in ctDNA+ and not reached in ctDNA- group (HR:17.5; IC95%:1.9-157.3; p=0.01). Data are immature for OS analysis. Conclusions: CtDNA immediately post-CRT has a high predictive value in patients with anal and cervical tumors in early access CRT non-responders, who are at a high risk of disease progression. This biomarker should be considered for tailoring strategies of treatment escalation in this population.

Comparative analysis of ChatGPT-4.0’s management of six gastrointestinal cancers according to the NCCN guidelines.

e13654 Background: The integration of Natural Language Processing (NLP) into healthcare holds tremendous promise. ChatGPT-4.0 (OpenAI, San Francisco, CA) is a widely recognized large language model that can comprehend and generate text, answer questions, and perform other language-related tasks. However, pitfalls and errors have been described in its clinical application. We explored the ability of ChatGPT-4.0 (ChatGPT) to guide clinical decision-making in 6 gastrointestinal cancers using the National Comprehensive Cancer Network (NCCN) Clinical Practice Guidelines as a framework. Methods: We reviewed the NCCN Guidelines for Anal Squamous Cell Carcinoma (AN), Small Bowel Adenocarcinoma (SB), Ampullary Adenocarcinoma (AA), Biliary Tract Cancers (BT), Pancreatic Adenocarcinoma (PN), and Gastric Cancer (GA). Up to 2 clinical questions were designed for each decision-making page. Questions were categorized by type ( Wo rkup, Treatment, Surveillance, Diagnostics, or References). ChatGPT was queried in a reproducible fashion. To account for variable prompt engineering of our non-validated assessment tool, up to 3 follow-up questions were allowed. Responses were rated on a Likert scale: 5) Correct; 4) Correct, with missing information requiring clarification; 3) Correct, but unable to complete answer; 2) Partially incorrect; 1) Absolutely incorrect. Subgroup analysis was conducted on Correctness (defined as scores 1-2 vs 3-5) and Accuracy (scores 1-3 vs 4-5). Variance between ChatGPT responses to each cancer was analyzed. Descriptive statistics were used, and significance was tested with binary logistic regression. Results: A total of 270 questions were generated (range per cancer 32-68). The score frequency distribution was: 5) 45.2%; 4) 19.3%; 3) 13.3%; 2) 13.7%; and 1) 8.5%. On subgroup analysis, Correctness was seen in 210 (77.8%) of questions, and Accuracy with 174 (64.4%). The difference in Correctness scores between cancers was not statistically significant, and there was no statistically significant difference in scores by question type. There was a statistically significant difference in the Accuracy of ChatGPT between cancers (Table). Conclusions: ChatGPT was significantly more likely to provide accurate responses to questions regarding GA and PN versus AN or SB. It demonstrates a limited capacity to assist with complex clinical decision-making in 6 gastrointestinal cancers. However, the Accuracy level is below the acceptable threshold for implementation into clinical use. Further analysis of the expanding capabilities of ChatGPT and other NLP-based tools is warranted in this rapidly evolving domain. Future studies would benefit from a validating grading instrument. [Table: see text]

Preliminary results from a first-in-human trial of AMT-116, a topoisomerase I inhibitor containing antibody-drug conjugate (ADC), in patients with advanced solid tumors.

e15010 Background: CD44v9 is a tumor-associated antigen highly expressed in various solid tumor types including head and neck, lung, esophageal, pancreatic, colorectal, breast, bladder, hepatic, cervical, and gastric cancers. AMT-116 is a first-in-class antibody-drug conjugate (ADC) targeting CD44v9, by conjugating a novel topoisomerase I inhibitor, belotecan derivative named KL610023 (Sichuan Kelun-Biotech) to a humanized anti-CD44v9 immunoglobulin G1 (IgG1) antibody via a hydrolysable linker with an average drug-to-antibody ratio of 7-8. Methods: This is an ongoing first-in-human, non-randomized, open-label, multicenter, Phase 1 study designed to evaluate the safety, tolerability, pharmacokinetics, and preliminary anti-tumor activity of AMT-116 in patients (pts) with advanced solid tumors, unselected for target expression. Pts received escalating doses of AMT-116 Q2W starting from 1.5 mg/kg guided by the Bayesian logistic regression model (BLRM) following escalation with overdose control (EWOC) principle. Results: As of Feb 1, 2024, eight pts (4 pts at 1.5 mg/kg, 3 pts at 3 mg/kg and 1 pt at 5 mg/kg) have been treated in Australia and pts at 1.5 mg/kg and 3 mg/kg completed the 28-day dose-limiting toxicity (DLT) evaluation period. No DLT events were observed, and the maximum tolerated dose (MTD) has not been reached. Treatment related adverse events (TRAEs) were reported in 5 pts out of 8. The most common TRAEs were fatigue (n=3) and nausea (n=3). Only one Grade 3 TRAE (leukopenia) was reported. There were no Grade 4 or 5 TRAEs or treatment-related SAEs. Seven pts have completed at least one post-treatment tumor assessment. At dose level 3 mg/kg, one pt with anal squamous cell carcinoma achieved unconfirmed PR with a 31% tumor shrinkage and one pt with hepatocellular carcinoma achieved SD with a 23% tumor shrinkage from baseline. Subject enrollment in 5 mg/kg is underway. Conclusions: These preliminary data indicate that AMT-116 is well tolerated at the first two dose levels in patients with heavily pretreated advanced solid tumors. Dose escalation is ongoing. Clinical trial information: NCT05725291 .