Appendiceal Adenocarcinoma Research Articles

Negative Impact of Systemic Therapy on Survival in Patients Undergoing Cytoreductive Surgery and Hyperthermic Intraperitoneal Chemotherapy for Low-Grade Metastatic Appendiceal Adenocarcinoma.

Despite studies demonstrating that patients with peritoneal metastases from low-grade appendiceal adenocarcinoma (AA) do not respond well to systemic chemotherapy (SC), patients frequently undergo combination of SC with cytoreductive surgery/hyperthermic intraperitoneal chemotherapy (CRS/HIPEC) regardless of grade. A nationwide retrospective analysis using the National Cancer Database evaluated patients with AA with peritoneal metastasis from 2016 to 2021. Cox proportional hazards model was used to evaluate the impact of SC in addition to CRS/HIPEC on overall survival (OS) stratified by tumor grade. A total of 1,449 patients were included: 481 low-grade, 428 intermediate-grade, and 540 high-grade tumors. Clinical variables, such as age, sex, and comorbidity index, were similar across tumor grades. Cytoreductive surgery/hyperthermic intraperitoneal chemotherapy without SC was utilized in 65.73% of low-grade cases compared with 41.01% in intermediate-grade and 11.11% in high-grade cases. Systemic chemotherapy was utilized alone in 17.74% and with CRS/HIPEC in 16.53% of low-grade cases. In adjusted survival analysis, addition of SC to CRS/HIPEC was associated with worse OS for patients with low-grade AA (hazard ratio [HR] 2.77, 95% confidence interval [CI] 1.18-6.50) but not for intermediate (HR 1.65, 95% CI 0.82-3.35) and high-grade tumors (HR 1.18, 95% CI 0.67-2.45). The addition of time to definitive surgery variable nullified the negative impact of adding SC to CRS/HIPEC in low-grade AA (HR 1.76, 95% CI 0.68-4.53). Negative OS impact of SC may be mediated by delays in effective surgical/intraoperative therapy. If CRS/HIPEC is planned for patients with metastatic low-grade AA, avoiding SC may facilitate earlier surgical intervention and improve survival.

Positive 68Ga-FAPI-04 PET/MRI and Negative 18F-FDG PET/CT Imaging in Incidental Appendiceal Goblet Cell Adenocarcinoma.

A 70-year-old woman presented with left ovarian mass and thickened peritoneum. 18F-FDG PET/CT showed no significant FDG-avid in the whole body. 68Ga-FAPI-04 demonstrated abnormally high FAPI uptake in the ileocecal region, left ovarian lesion, and thickened peritoneum. The postoperative pathology confirmed the appendiceal goblet cell adenocarcinoma. This case highlights the superior and innovative diagnostic role of 68Ga-FAPI-04 in appendiceal goblet cell adenocarcinoma and its metastases.

Appendiceal adenocarcinoma-patterns of tumor spread and prognosis

IntroductionAppendiceal adenocarcinoma represents a diagnostic and therapeutic challenge since it is prone to early lymphatic and peritoneal spread. We aimed to analyze the proportion of lymph node metastases in completion right hemicolectomy specimens, risk factors for peritoneal metastases (PM), and prognosis after definitive treatment. MethodsNinety-three patients with appendiceal adenocarcinoma scheduled for cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (CRS + HIPEC) in Uppsala 2004–2020 were identified from a prospectively maintained registry. Risk factors for PM were assessed based on the presence (CT + group, n = 55) or absence (CT – group, n = 37) of visible PM at baseline CT scan. Prognostic factors were analyzed based on the actual presence (PM group, n = 66) or absence (no PM group, n = 27) of PM. ResultsThe median age was 60 (26–78). Forty-eight patients were women. Resection of PM at initial surgery indicated an 80 % risk of finding PM at a follow-up exploration. R1 appendectomy and perforated appendix had a similar risk for PM (24 %,26 %) which increased to 38 % if both were present.Regional lymph node metastases occurred in 31 % in the CT + group vs. 14 % in the CT − group (p = 0.005) and was associated with poor survival HR 5.16 (1.49–17.81).The 5-year OS and DFS rates were 54 % and 29 % in the PM group. ConclusionsPatients with certain risk factors have a high likelihood of PM despite a normal CT scan, which justifies selective exploration at a HIPEC center. Regional lymph node spread supports the current practice of completion right hemicolectomy and is a significant prognostic factor.

Prognostic analysis of appendectomy versus right hemicolectomy for T1 appendiceal adenocarcinoma: a multicenter retrospective analysis

Background and aimAppendiceal adenocarcinoma, an exceedingly rare malignancy, sparks debate on the optimal surgical approach—appendectomy or right hemicolectomy—for early-stage cases. This study aims to investigate the impact of these two surgical methods on the survival prognosis of patients with early appendiceal adenocarcinoma.MethodUtilizing a multicenter medical database, we gathered data from 168 patients diagnosed with T1 stage appendiceal adenocarcinoma admitted between January 2008 and January 2015. This study aims to compare the impact of different treatment modalities on the prognosis of appendiceal adenocarcinoma in these two groups.ResultIn patients diagnosed with T1 appendiceal adenocarcinoma, the survival prognosis was not significantly improved with right hemicolectomy compared to appendectomy. Out of one hundred twenty-seven patients undergoing right colon resection, only three exhibited lymphatic metastasis, resulting in a rate of 2.3%.ConclusionSimple appendectomy can fulfill the objective of achieving radical tumor resection, rendering right hemicolectomy unnecessary.

Mutational Features and Tumor Microenvironment Alterations in High-Grade Appendiceal Cancers Treated With Iterative Hyperthermic Intraperitoneal Chemotherapy.

High-grade appendiceal adenocarcinomas (HGAA) with peritoneal metastases (PMs) are associated with poor survival. Hyperthermic intraperitoneal chemotherapy (HIPEC) is a novel treatment approach for unresectable HGAA-PM. However, its influence on immunogenomic profiles has not yet been fully explored. We obtained 79 samples of metastatic peritoneal tumor deposits from patients diagnosed with HGAA and performed whole-exome sequencing, RNA sequencing, and immunoprofiling before and after HIPEC. Tumor biopsies were subjected to immunogenomic profiling to detect mutational signatures and immune populations associated with oncologic outcomes. Fifteen patients with HGAA-PMs were included in the study. The median progression-free survival (PFS) was 6.7 months (2.7-25.3) and the median overall survival was 11.4 months (4.7-42). Mucin-associated genes (MUC16, MUC3A, and MUC5AC) and titin (TTN) had the highest mutation frequencies. Mutational signatures such as single-base substitution 29 and doublet-base substitution 11 were present in >50% of single-base and double-base mutations. Higher PD-L1 coexpression on CD8+ T cells demonstrated a higher PFS both intratumorally (P = .019) and at the margin (P = .025). HIPEC-associated mutational signatures were identified in HGAA-PMs. Elevated PD-L1+ cytotoxic T-cell populations after HIPEC had better PFS, offering valuable insights for prognostication in the context of HIPEC treatment.

Molecular and Clinicopathologic Impact of GNAS Variants Across Solid Tumors.

The molecular drivers underlying mucinous tumor pathogenicity are poorly understood. GNAS mutations predict metastatic burden and treatment resistance in mucinous appendiceal adenocarcinoma. We investigated the pan-cancer clinicopathologic relevance of GNAS variants. We assessed 58,043 patients with Memorial Sloan Kettering-Integrated Mutation Profiling of Actionable Cancer Targets (IMPACT)-sequenced solid tumors to identify oncogenic variants, including GNAS, associated with mucinous tumor phenotype. We then performed comprehensive molecular analyses to compare GNAS-mutant (mut) and wild-type tumors across cancers. Gene expression patterns associated with GNAS-mut tumors were assessed in a The Cancer Genome Atlas cohort. Associations between GNAS variant status and peritoneal metastasis, first-line systemic therapy response, progression-free survival (PFS), and overall survival (OS) were determined using a propensity-matched subcohort of patients with metastatic disease. Mucinous tumors were enriched for oncogenic GNAS variants. GNAS was mutated in >1% of small bowel, cervical, colorectal, pancreatic, esophagogastric, hepatobiliary, and GI neuroendocrine cancers. Across these cancers, GNAS-mut tumors exhibited a generally conserved C-to-T mutation-high, aneuploidy-low molecular profile with co-occurring prevalent KRAS variants (65% of GNAS-mut tumors) and fewer TP53 alterations. GNAS-mut tumors exhibited recurrently comutated alternative tumor suppressors (RBM10, INPPL1) and upregulation of MAPK and cell surface modulators. GNAS-mut tumors demonstrate an increased prevalence of peritoneal metastases (odds ratio [OR], 1.7 [95% CI, 1.1 to 2.5]; P = .006), worse response to first-line systemic therapy (OR, 2.2 [95% CI, 1.3 to 3.8]; P = .003), and shorter PFS (median, 5.6 v 7.0 months; P = .047). In a multivariable analysis, GNAS mutated status was independently prognostic of worse OS (hazard ratio, 1.25 [95% CI, 1.01 to 1.56]; adjusted P = .04). Across the assessed cancers, GNAS-mut tumors exhibit a conserved molecular and clinical phenotype defined by mucinous tumor status, increased peritoneal metastasis, poor response to first-line systemic therapy, and worse survival.

Appendiceal goblet cell adenocarcinoma with perineural invasion extending into the ileocecal lesion

BackgroundAppendiceal goblet cell adenocarcinoma (GCA) is a rare subtype of primary appendiceal adenocarcinoma with an incidence of 1–5 per 10,000,000 people per year. Appendiceal tumors are often diagnosed after appendectomy for acute appendicitis. Notably, however, there is currently no standard treatment strategy for GCA, including additional resection. We report a case of appendiceal GCA with perineural extension into the cecum, in which ileal resection was considered effective.Case presentationA 41-year-old man was diagnosed with acute appendicitis and underwent appendectomy. Histopathological findings revealed GCA (T3, Pn1). He was referred to our hospital for additional resection. Preoperative examination indicated a diagnosis of GCA cT3N0M0. Laparoscopic ileocecal resection and D3 lymph node dissection were performed 2 months after initial appendectomy. The patient had a good postoperative course and was discharged 8 days after surgery. Histopathological findings showed a GCA invading the cecum, despite an intact appendiceal stump, no lymph node metastasis, no vascular invasion, and no horizontal extension into the submucosa. Direct invasion of the tumor through the serosa was not observed, but perineural extension was conspicuous in the cecum, suggesting that the GCA extended into the cecum via perineural invasion. The resection margins were negative. The patient has survived free of recurrence for a year after ileocecal resection.ConclusionsThe current patient was diagnosed with appendiceal GCA following appendectomy for acute appendicitis. Despite intact of appendiceal stump and no evidence of lymph node or distant metastasis, he underwent laparoscopic ileocecal resection and D3 lymph node dissection 2 months after initial appendectomy, with a favorable outcome. Despite the detection of perineural invasion, the patient declined adjuvant therapy. This case suggests that extensive resection may be required in patients with appendiceal GCA, but the role of adjuvant therapy remains unclear.

High-Grade Appendiceal Mucinous Neoplasm Mimicking Appendiceal Tubulovillous Adenoma: A Case Report and Literature Review.

High-grade appendiceal mucinous neoplasm (HAMN) has been separated from appendiceal adenocarcinoma recently as an independent entity and categorized into appendiceal mucinous neoplasms. These neoplasms demonstrate distinct histological characteristics, including architectures and appendiceal mural changes similar to low-grade appendiceal mucinous neoplasm but with high-grade cytology, and no infiltrative invasion. Overt mucinous feature are not evident in some cases as the high-grade neoplastic epithelium may show intracytoplasmic mucin reduction. Occasionally, the neoplastic epithelial cells show florid proliferation and tubulovillous configuration and may be misdiagnosed as appendiceal tubulovillous adenoma. We report the case of a 67-year-old woman with appendicular dilatation and luminal mucin. She underwent an ileocecoectomy. The appendiceal lesion was found histologically to be a HAMN, which closely resembled appendiceal tubulovillous adenoma. The tumor cells demonstrated wild-type p53 expression and mismatch repair proficiency by immunochemistry. Molecular testing showed 1 KRAS mutation, 2 PIK3CA mutations, and 1 BRCA2, EP300, TGFBR2, CHD4, CREBBP, FANCC, PKHD1 mutation each in the tumor. The patient was followed up for 1 year with no evidence of disease.

Minimum number of lymph nodes to maximize survival in non-metastatic appendiceal adenocarcinoma

IntroductionIn non-metastatic appendiceal adenocarcinoma, the relationship between the number of lymph nodes harvested and overall survival is unknown. The objective of this study was to determine whether the number of lymph nodes harvested impacts survival in patients with mucinous and non-mucinous appendiceal cancer. MethodsRetrospective cohort analysis was conducted in patients who underwent surgery for appendiceal adenocarcinoma in the SEER database from 2000–2019. Exclusion criteria included patients without the number of regional nodes harvested/node positivity, missing survival data, stage IV disease, and certain subtypes of appendiceal tumors. The primary outcome was 10-year overall survival. ResultsA total of 1651 patients were identified, 1101 with mucinous and 550 with non-mucinous cancer. The majority of patients were male (54 %) and between the ages of 50–74 (52 %). Mean ± SD number of lymph nodes harvested was 17.04 ± 10.41. The ten-year survival rates for patients with mucinous appendiceal cancer were 43–74 % and 25–68 % for non-mucinous cancer, depending on AJCC stage. Multivariate Cox-regression analysis displayed that the number of lymph nodes harvested was an independent predictor of survival (p < 0.0001). The optimal threshold predicted by Cox-regression for maximal survival benefit was harvest of a minimum of 15 nodes for mucinous and 12 for non-mucinous cancer. Additionally, for mucinous cancer, per each additional 3 nodes harvested past 15, the 10-year risk of mortality decreased by 7 % (HR 0.93 (0.88 to 0.98), p < 0.001). ConclusionsThe number of lymph nodes harvested is an independent predictor of survival for patients with appendiceal adenocarcinoma. To maximize this survival benefit, a minimum of 15 regional lymph nodes must be harvested for mucinous and 12 for non-mucinous cancer.

Appendiceal goblet cell adenocarcinoma newly classified by WHO 5th edition: a case report (a secondary publication)

BackgroundAppendiceal goblet cell adenocarcinoma (AGCA) is a newly proposed cancer type in the 5th edition of the WHO Classification of Tumours in 2019. We experienced this rare form of appendiceal primary neoplasm.Case presentationAn 85-year-old male presented a positive fecal occult blood test. A series of imagings revealed a type 1 tumor, located on the appendiceal orifice. The subsequent biopsy made the diagnosis of signet-ring cell carcinoma. Consequently, he underwent the laparoscopic-assisted ileocecal resection. Initially, the tumor was suspected to be a Goblet cell carcinoid (GCC). There was a discrepancy between the histological and immunostaining findings: the tumor cells exhibited morphological similarities to GCCs, however displayed limited staining upon immunostaining. Ultimately, we concluded that the tumor should be classified as AGCA, by following WHO 5th Edition. AGCA represents a newly categorized subtype of adenocarcinomas. Because of our preoperative suspicion of malignancy, we performed tumor resection with regional lymph node dissection, despite the fact that most appendiceal malignant tumors are typically identified after an appendectomy.ConclusionWe experienced a case that provides valuable insights into the comprehension of AGCA, a recently established pathological entity in the WHO 5th Edition. This article is an acceptable secondary publication of a case report that appeared in Azuma et al. (J Jpn Surg Assoc 83:1103–1108, 2022)

Who should get a right colectomy in low-grade appendiceal adenocarcinomas? Association of lymphovascular invasion and nodal metastases

BackgroundThere is variation in the probability of nodal metastases from low-grade appendiceal adenocarcinomas, and the role of right colectomy is unclear. We aimed to define the prevalence and utility of lymphovascular invasion in predicting the risk of nodal metastases to help stratify patients who may benefit from right hemicolectomy. MethodsPatients with nonmetastatic low-grade appendiceal adenocarcinomas were identified from the National Cancer Database (2010–2017). The primary outcome was probability of nodal metastases. Logistic regression was used to identify independent predictors of nodal metastases. A 4-tier risk model—the COH Composite Score—was calculated by assigning 1 point each for a high-risk feature (lymphovascular invasion, T3/T4 T stage, or nonmucinous histology). Survival analysis was performed using the Kaplan-Meier method. Multivariate Cox regression analysis was used to identify independent predictors of survival. ResultsA total of 1,303 patients with nonmetastatic low-grade appendiceal adenocarcinomas (64.2% mucinous) were identified. Of the 1,133 patients with known lymphovascular invasion status, 78 (6.9%) were lymphovascular invasion positive. In multivariate analysis, lymphovascular invasion was independently associated with nodal metastases (odds ratio, 8.68; P < .001). Overall accuracy of lymphovascular invasion in predicting nodal metastases was 86%. The COH Composite Score stratified patients in 4 categories with increasing risk of nodal metastases and incrementally worse survival. For patients with the COH Composite Score of 0 (12%), the nodal metastasis rate was 3.1%, and a right hemicolectomy in this group did not improve survival. ConclusionThe presence of lymphovascular invasion is strongly predictive of nodal metastases. Lymphovascular invasion as part of the COH Composite Score may help guide the extent of surgery in low-grade appendiceal adenocarcinomas.

Critical appraisal of total gastrectomy plus total colectomy with hyperthermic intraperitoneal chemotherapy as a treatment for advanced pseudomyxoma peritonei

AbstractBackgroundThe absolute requirement for a long‐term favorable result with cytoreductive surgery for pseudomyxoma peritonei is a complete resection of all visible disease. A combination of parietal peritonectomy procedures and visceral resections is required for this to occur. The cytoreductive surgery is supplemented by hyperthermic intraperitoneal chemotherapy.MethodsWe searched our database and secured files for patients who required a total gastrectomy and a total colectomy to achieve a complete cytoreductive surgery. Survival of low‐grade mucinous neoplasm (LAMN) and mucinous appendiceal adenocarcinoma (MACA) histologies were determined. Clinical and histologic variables were assessed for their impact on survival.ResultsThirteen of 450 patients (2.9%) with LAMN histology and 14 of 186 patients (7.5%) with MACA histology had these visceral resections. Median survival of these 27 patients was 10 years. LAMN and MACA patients showed the same survival. For LAMN histology, this requirement for extensive visceral resection markedly reduced survival (p &lt; 0.0001). For MACA, there was no adverse impact on survival (p = 0.4359). Class 4 adverse events caused reduced survival (p = 0.0014).ConclusionsA 10‐year median survival accompanies total gastrectomy plus total colectomy for advanced pseudomyxoma peritonei. Systemic chemotherapy and class 4 adverse events reduced survival.

Travel distance does not affect overall survival in patients with appendiceal adenocarcinoma undergoing cytoreductive surgery and hyperthermic intraperitoneal chemotherapy

IntroductionCytoreductive surgery and hyperthermic intraperitoneal chemotherapy (CRS-HIPEC) is a potentially curative approach for appendiceal cancer (AC) with peritoneal dissemination and is most often employed at tertiary referral centers. Regionalization may provide geographic barriers to care for vulnerable patients. The aim of this study was to examine the effect of travel distance on oncologic outcomes of patients with AC treated with CRS-HIPEC. MethodsThe National Cancer Database (NCDB) was reviewed from 2006 through 2020 for patients with AC who underwent CRS-HIPEC. The primary comparison variable was distance (<50 miles vs ≥ 50 miles from the CRS-HIPEC facility). Demographic and tumor characteristics were analyzed. Primary outcome was overall survival (OS). Secondary outcomes were 30-day and 90-day mortality, readmission, and length of stay (LOS). ResultsDuring the study period, 1703 patients met inclusion criteria, with 1000 patients travelling < 50 miles for CRS-HIPEC (59 %) and 703 travelling ≥ 50 miles (41 %). Patients who traveled ≥ 50 miles were more likely to be non-Hispanic White (p < 0.001), have annual income less than $74,062, be treated at an academic center and live in the South-Atlantic region of the United States. There was no significant difference in OS between groups (Figure 1). There were no significant differences in 30-day postoperative survival, 90-day survival, or 30-day readmission. Post-operative LOS was 8.0 versus 9.0 days (p < 0.001). ConclusionsTravel distance ≥ 50 miles was not significantly associated with decreased OS or increased postoperative mortality, suggesting that regionalization of care does not worsen oncologic outcomes for patients with AC undergoing CRS-HIPEC.

Early-onset appendiceal adenocarcinoma (EOAA): 10-year experience from a single center.

4178 Background: The incidence of early-onset (age &lt;50) gastrointestinal cancers, including early onset Appendiceal Adenocarcinoma (EOAA) is on the rise, however reported data on etiology, treatment, and outcomes is scarce. Here we present outcomes for EOAA patients treated at a single high-volume center. Methods: Records of patients (pts) with EOAA were reviewed. Clinicopathological and genomic data were abstracted. Pts aged 18 - 49 years at diagnosis with Appendiceal Adenocarcinoma (AA) seen at UCMC between 2013 - 2023 were included. The primary outcome of Overall survival (OS) was analyzed using univariable Cox proportional hazards regression analysis. Results: 116/492 (23.6%) appendix cancer pts seen at UCMC had early-onset disease. 45 pts met eligibility (Table). 10/20 (50%) pts with localized disease had recurrence after hemicolectomy (median recurrence free survival = 41.6 months; 95% CI, 34.3 – NR; follow-up = 46.42 months). 22/44 (50%) pts had mucinous AA, 21 (47.7%) goblet cell AA, and 1 (2.33%) had poorly differentiated AA. In 35 pts with metastatic/recurrent disease, mOS was 35.93 months (95% CI, 28.4 – NR). Lymphovascular (LVI) or perineural invasion (PNI) (HR, 6.41; 95% CI, 2.10 – 19.59, p = 0.001), lymph nodes metastasis (HR, 13.11; 95% CI, 3.53 – 48.68; p &lt; 0.001), and grade 3 disease (vs. grade 1; HR, 5.28; 95% CI, 1.43 – 19.51, p = 0.01) were prognostic for worse OS in univariable analysis. Cytoreductive surgery (CRS), irrespective of completeness, was associated with improved OS (HR = 0.21; 95% CI, 0.09 – 0.53; p &lt; 0.001). Next Generation Sequencing results were available in 20 cases: KRAS (n = 10, 50%), TP53(n = 7, 35%), GNAS (n = 6, 30%), SMAD4 (n = 4, 20%), and MYC (n = 3, 15%) were frequently altered. Alterations with potential therapeutic targets were seen in 12/20 (60%) cases. 10 pts had germline testing with 2 (20%) pathogenic alterations detected: SDHA(H447Mfs*23) and CHEK2 (T367Mfs*15). The pt with CHEK2 mutation had AA as the only malignancy, was the youngest (age 26.17) and passed away 17.26 months after diagnosis. Conclusions: A considerable number of patients with AA may have early-onset disease. A median OS of about 3 years in this young and vulnerable patient population is alarming. As in late-onset disease, EOAA is often incidentally diagnosed. LVI or PNI may be associated with poorer outcomes and deserve additional consideration for risk stratification. Many patients have targetable genomic alterations and should be included in clinical trials where current enrollment is often unsatisfactory for AA. Germline mutation testing in patients with EOAA should be widely implemented. [Table: see text]

228P BRAF mutation in appendiceal adenocarcinoma: Key contrasts with colorectal cancer and implications for treatment

228P BRAF mutation in appendiceal adenocarcinoma: Key contrasts with colorectal cancer and implications for treatment

A novel oral microtubule inhibitor utidelone capsule (UTD2): A phase 1 clinical study to assess the tolerability, safety, and efficacy in advanced solid tumors.

e15014 Background: Utidelone is a potential best-in-class novel microtubule stabilizing agent that offers several advantages including improved efficacy and safety, broader anti-cancer spectrum, blood-brain barrier penetrance, and response against multidrug-resistant tumors. Utidelone injection (UTD1) has been approved for advanced breast cancer in China since 2021 (30 mg/m2/d-5day in combination with capecitabine; 35mg/m2/d-5day for monotherapy’s recommended dose). Utidelone is not susceptible to P-glycoprotein, leading to better oral bioavailability and successful development of an oral capsule. This is the first-in-human study of Utidelone Capsule (UTD2) in the United States. Methods: This is an ongoing phase I, open-label, dose escalation study (NCT05681000). Eligible patients are aged ≥18, and have an ECOG PS of 0-1, life expectancy ≥12weeks, adequate organ functions, pathologic confirmed advanced solid tumor refractory to prior standard therapies. Patients are treated with UTD2 monotherapy. The starting dose is 25 mg/m2/d-5day, with planned escalation to 50, 75, 100 mg/m2/d-5day, 70 mg/m2/d-7day and 85 mg/m2/d-7day in a 21-day cycle. The primary objective is to determine DLT and MTD. Secondary objectives include efficacy, pharmacokinetic profile and phase II dose recommendation. Results: As of 22nd January 2024, 10 advanced solid tumor patients were enrolled with median age of 62.5 years (range 52.0-81.0), 5 females and 5 males. All patients had received prior treatment in advanced settings. Dose escalation is ongoing, and 100mg/m2/d-5day cohort is under evaluation. The first 8 patients were evaluated for efficacy with an outcome of 1 CR (ovarian cancer), 5 SD (prostate adenocarcinoma, testicular Sertoli cell tumor, non-small cell lung cancer, pancreatic adenocarcinoma and appendiceal adenocarcinoma) and 2 PD (carcinoma of fallopian tube and adenocarcinoma of sigmoid colon), among whom 5 patients are still on the treatment with durations of 2 to 11 cycles. The ovarian patient with CR was enrolled to the lowest dose cohort, and is still on treatment. She is heavily pre-treated with multiple prior lines including chemotherapies. Regarding safety, most treatment-emergent adverse events (TEAEs) were Grade 1/2, manageable, and included diarrhoea, nausea, alopecia. There were two cases of Grade 3 diarrhea that recovered to Grade 1 through dose reduction or medical support. No grade 4 or 5 adverse events and no treatment discontinuations due to AE were reported. There have been no DLTs and the MTD is not yet reached. Conclusions: This study has demonstrated encouraging anti-tumor activity with good tolerance and manageable safety profile of UTD2 in patients with heavily pre-treated advanced solid tumors. This study is still actively ongoing, and further data will be provided at time of presentation. Clinical trial information: NCT05681000 .

227P Clinical outcomes and molecular characterization of appendiceal goblet cell adenocarcinoma in 414 patients

227P Clinical outcomes and molecular characterization of appendiceal goblet cell adenocarcinoma in 414 patients

Efficacy and Safety of Atezolizumab and Bevacizumab in Appendiceal Adenocarcinoma.

Appendiceal adenocarcinoma (AA) remains an orphan disease with limited treatment options for patients unable to undergo surgical resection. Evidence supporting the efficacy of combined VEGF and PD-1 inhibition in other tumor types provided a compelling rationale for investigating this combination in AA, where immune checkpoint inhibitors have not been explored previously. We conducted a prospective, single-arm phase II study evaluating efficacy and safety of atezolizumab in conjunction with bevacizumab (Atezo+Bev) in advanced, unresectable AA. Patients treated with the Atezo+Bev combination had 100% disease control rate (1 partial response, 15 stable disease) with progression-free survival (PFS) of 18.3 months and overall survival not-yet-reached with median duration of follow-up of 40 months. These survival intervals were significantly longer relative to a clinically and molecularly matched synthetic control cohort treated with cytotoxic chemotherapy designed for colorectal cancer (PFS of 4.4 months, P = 0.041). In light of recent data demonstrating a lack of efficacy of 5-fluorouracil-based chemotherapy, Atezo+Bev is a promising treatment option for patients with low-grade unresectable AA; further study is warranted. AA remains an orphan disease with limited systemic therapy options for patients who are not candidates for surgical resection. These data suggest activity from combined VEGF and PD-L1 inhibition that warrants further study.

Critical reappraisal of prognostic indicators for 949 mucinous appendiceal neoplasm patients.

The standard of care for treatment of an appendiceal mucinous neoplasm with peritoneal dissemination is cytoreductive surgery (CRS) combined with hyperthermic intraperitoneal chemotherapy (HIPEC). These two treatments are combined in the operating room. A crucial requirement for benefit long-term is proper patient selection. Clinical and histopathologic prognostic indicators are used, along with the patient's fitness for surgery, to select patients to receive CRS and HIPEC. This study seeks to identify the reliable prognostic indicators for four different groups of patients. They are (1) the low-grade appendiceal mucinous neoplasms (LAMN) with a complete CRS, (2) the mucinous appendiceal adenocarcinomas (MACA) with complete CRS, (3) MACA with lymph node metastases (MACA-LN) with complete CRS, and (4) all histologic subtypes with incomplete cytoreduction. The prognostic indicators were evaluated for their impact on overall survival in these four groups of patients. The completeness of cytoreduction (CC) score statistically significantly showed survival differences in all three histologic subtypes. The peritoneal cancer index (PCI) showed significance with LAMN and MACA-LN but not with MACA and not with incomplete CRS. The prior surgical score (PSS) was a prognostic indicator that predicted the outcome with LAMN, MACA-LN, and incomplete CRS patients but not with the MACA group. Patients who were symptomatic or who had extensive systemic chemotherapy before CRS had a significantly reduced survival. The utility of prognostic indicators varied greatly within our four different groups of appendiceal mucinous neoplasms. CC score was always a reliable prognosticator. Surprisingly, PCI was not.

ASO Visual Abstract: Extent of Resection and Long-Term Outcomes for Appendiceal Adenocarcinoma: A SEER Database Analysis of Mucinous and Non-mucinous Histologies.

ASO Visual Abstract: Extent of Resection and Long-Term Outcomes for Appendiceal Adenocarcinoma: A SEER Database Analysis of Mucinous and Non-mucinous Histologies.