Appendiceal Mucinous Adenocarcinoma Research Articles

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.

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 < 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.

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

4178 Background: The incidence of early-onset (age <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 < 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 < 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]

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.

The extracellular matrix in peritoneal metastatic carcinoma

The peritoneum is a relatively common site for the metastasis of cancers that develop near the peritoneal cavity, such as gastric cancer, colorectal cancer (CRC), ovarian cancer, and low-grade appendiceal mucinous adenocarcinoma (LAMN). Peritoneal metastasis (PM) results from direct implantation and growth or microvascular metastasis of cancer cells to the peritoneum and is often associated with a poor prognosis. The biological features of peritoneal metastatic tumours are significantly altered, and the tumour microenvironment (TME) is profoundly abnormal. The extracellular matrix (ECM), a highly dynamic part of the TME, exhibits unique biological properties and influences tumour cells (TCs) behaviour and invasion. In this review, I focus on the hallmarks of cancer; the biology of CRC, PM from CRC, LAMN and pseudomyxoma peritonei (PMP, resulting from the intraperitoneal spread of LAMN); and the structural features of the cancer ECM and mucus and their roles in tumour growth, TCs invasion and drug resistance. The study of the ECM has led to a deeper understanding of peritoneal metastatic tumours and provides new insights for developing new biomarkers and targeted drugs.

Role of colectomy in the management of appendiceal tumors: a retrospective cohort study

BackgroundAppendiceal tumors represent a range of histologies that vary in behavior. Recommendations for treatment with appendectomy versus right hemicolectomy (RHC) for different tumor types are evolving and sometimes conflicting. This study sought to characterize variation in the United States around surgical treatment of major appendiceal tumor types over time and describe differences in outcomes based on procedure.MethodsPatients diagnosed with appendiceal goblet cell adenocarcinoma (GCA), mucinous adenocarcinoma, neuroendocrine neoplasm (NEN), or non-mucinous adenocarcinoma from 2004–2017 were identified in the National Cancer Database. Trends in RHC over time and predictors of RHC were identified. Surgical outcomes for each histologic type and stage were compared.ResultsOf 18,216 patients, 11% had GCAs, 34% mucinous adenocarcinoma, 31% NENs, and 24% non-mucinous adenocarcinoma. Rate of RHC for NEN decreased from 68% in 2004 to 40% in 2017 (p = 0.008) but remained constant around 60–75% for other tumor types. Higher stage was associated with increased odds of RHC for all tumor types. RHC was associated with higher rate of unplanned readmission (5% vs. 3%, p < 0.001) and longer postoperative hospital stay (median 5 days vs. 3 days, p < 0.001). On risk-adjusted analysis, RHC was significantly associated with increased survival versus appendectomy for stage 2 disease of all tumor types (HRs 0.43 to 0.63) and for stage 1 non-mucinous adenocarcinoma (HR = 0.56).ConclusionsMost patients with appendiceal tumors undergo RHC, which is associated with increased readmission, longer length of stay, and improved survival for stage 2 disease of all types. RHC should be offered selectively for appendiceal tumors.

A Case of Double Primary Carcinoma was Accidentally Found During Operation: Hepatocellular Carcinoma and Appendiceal Mucinous Adenocarcinomas

Background: Synchronous double primary cancer of hepatocellular carcinoma (HCC) and appendiceal mucinous adenocarcinomas has not been reported. Liver metastasis of digestive tract tumors is so common that it is easy to ignore the existence of double primary cancer in the digestive system. The appendiceal malignant tumor itself is easy to be misdiagnosed or missed. For a better understanding of HCC and appendiceal mucinous adenocarcinomas, the information on our recent case has been summarized. Case Presentation: A 58-year-old man was admitted with repeated upper abdominal pain for one week. Imaging examination and liver biopsy pathology were diagnosed as hepatocellular carcinoma. Colonoscopy showed no obvious organic lesions in the terminal ileum and the whole large intestine. We had anatomical resection of the S5 and S6 segments of the liver. At the same time, two suspicious lesions in the right liver were ablated by microwave. But at the end of the operation, we accidentally found a hard mass about 3 cm × 3 cm in size at the end of the appendix. And the rapid pathological results showed appendiceal adenocarcinoma, so we had a right hemicolectomy. So far, the diagnosis of the patient was changed to synchronous double primary cancer consisting of HCC and appendiceal mucinous adenocarcinomas. Conclusion: It is the first time we have reported a case of synchronous double primary hepatic cancer consisting of HCC and appendiceal mucinous adenocarcinomas in the world. Due to the rarity and unspecific clinical features, it is extremely challenging to be diagnosed preoperatively. It requires a more comprehensive understanding of the patient's medical history, careful physical examination, and comprehensive exploration of the abdominal cavity during the operation to avoid missed diagnosis. Patients with HCC and appendiceal mucinous adenocarcinomas are generally associated with poor prognosis. It needs we put forward new countermeasures for the new question.

Repeat Cytoreduction and Hyperthermic Intraperitoneal Chemotherapy for Recurrent Mucinous Appendiceal Adenocarcinoma: A Viable Treatment Strategy with Demonstrable Benefit

IntroductionMany patients with mucinous appendiceal adenocarcinoma experience peritoneal recurrence despite complete cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC). Prior work has demonstrated that repeat CRS/HIPEC can prolong survival in select patients. We sought to validate these findings using outcomes from a high-volume center.Patients and MethodsPatients with mucinous appendiceal adenocarcinoma who underwent CRS/HIPEC at MD Anderson Cancer Center between 2004 and 2021 were stratified by whether they underwent CRS/HIPEC for recurrent disease or as part of initial treatment. Only patients who underwent complete CRS/HIPEC were included. Initial and recurrent groups were compared.ResultsOf 437 CRS/HIPECs performed for mucinous appendiceal adenocarcinoma, 50 (11.4%) were for recurrent disease. Patients who underwent CRS/HIPEC for recurrent disease were more often treated with an oxaliplatin or cisplatin perfusion (35%/44% recurrent vs. 4%/1% initial, p < 0.001), had a longer operative time (median 629 min recurrent vs. 511 min initial, p = 0.002), and had a lower median length of stay (10 days repeat vs. 13 days initial, p < 0.001). Thirty-day complication and 90-day mortality rates did not differ between groups. Both cohorts enjoyed comparable recurrence free survival (p = 0.82). Compared with patients with recurrence treated with systemic chemotherapy alone, this select cohort of patients undergoing repeat CRS/HIPEC enjoyed better overall survival (p < 0.001).ConclusionsIn appropriately selected patients with recurrent appendiceal mucinous adenocarcinoma, CRS/HIPEC can provide survival benefit equivalent to primary CRS/HIPEC and that may be superior to that conferred by systemic therapy alone in select patients. These patients should receive care at a high-volume center in the context of a multidisciplinary team.

S3943 Appendiceal Mucinous Adenocarcinoma Presenting as Small Bowel Obstruction: A Rare Tumor With Rarer Presentation

S3943 Appendiceal Mucinous Adenocarcinoma Presenting as Small Bowel Obstruction: A Rare Tumor With Rarer Presentation

Determinants of Outcome with Reoperative Surgery for Pseudomyxoma Peritonei in 186 Patients.

To describe the long-term survival and clinical- and treatment-related variables that determine the outcome of repeat cytoreductive surgery (CRS) for mucinous appendiceal neoplasms with peritoneal dissemination. After patients with peritoneal dissemination of an appendiceal mucinous neoplasm have a CRS, disease progression may require secondary cytoreductive surgery (SCRS) and other treatments performed in a timely manner to prolong survival and help preserve an optimal quality of life. The clinical- and treatment-related variables associated with the index CRS and the SCRS were statistically assessed for their impact on survival. One hundred eighty-six of 687 complete CRS patients (27.1%) had SCRS. The median follow-up was 10 years and the median survival was 12 years. There were 95 males (51%) and the median age was 45.0 years. Survival benefit was associated with the index CRS by use of early postoperative intraperitoneal chemotherapy (EPIC) with 5-fluorouracil [Hazard ratio (HR), 0.4; P = 0.0004]. Also, survival of low-grade mucinous appendiceal neoplasms versus mucinous appendiceal adenocarcinoma (HR, 2.8; P < 0.0001) was improved. The interval between index CRS and SCRS was significant at ≤12 months versus 12-36 months versus >36 months (P < 0.0001). Change in peritoneal cancer index and disease distribution as focal or diffuse was significant by univariant and multivariant analyses. If the CRS was complete, the use of EPIC 5-fluorouracil, the interval between the index CRS and the SCRS, the histologic grade of the mucinous neoplasm, and the extent of recurrent disease were prognostic variables that should be used to help select patients for SCRS.

Intraperitoneal Paclitaxel Is a Safe and Effective Therapeutic Strategy for Treating Mucinous Appendiceal Adenocarcinoma.

The activity and safety of intraperitoneal paclitaxel in orthotopic PDX models of mucinous appendiceal adenocarcinoma supports the evaluation of intraperitoneal paclitaxel in a prospective clinical trial of this rare tumor type.

Efficacy of Systemic Chemotherapy in Patients With Low-grade Mucinous Appendiceal Adenocarcinoma

Appendiceal adenocarcinoma is a rare tumor, and given the inherent difficulties in performing prospective trials in such a rare disease, there are currently minimal high-quality data to guide treatment decisions, highlighting the need for more preclinical and clinical investigation for this disease. To prospectively evaluate the effectiveness of fluoropyrimidine-based systemic chemotherapy in patients with inoperable low-grade mucinous appendiceal adenocarcinoma. This open-label randomized crossover trial recruited patients at a single tertiary care comprehensive cancer center from September 2013 to January 2021. The data collection cutoff was May 2022. Enrollment of up to 30 patients was planned. Eligible patients had histological evidence of a metastatic low-grade mucinous appendiceal adenocarcinoma, with radiographic imaging demonstrating the presence of mucinous peritoneal carcinomatosis and were not considered candidates for complete cytoreductive surgery. Key exclusion criteria were concurrent or recent investigational therapy, evidence of bowel obstruction, and use of total parenteral nutrition. Data were analyzed from November 2021 to May 2022. Patients were randomized to either 6 months observation followed by 6 months of chemotherapy, or initial chemotherapy followed by observation. The primary end point was the percentage difference in tumor growth in treatment and observation groups. Key secondary end points included patient-reported outcomes in the chemotherapy and observation periods, objective response rate, rate of bowel complications, and differences in overall survival (OS). A total of 24 patients were enrolled, with median (range) age of 63 (38 to 82) years, and equal proportion of men and women (eg, 12 men [50%]); all patients had ECOG performance status of 0 or 1. A total of 11 patients were randomized to receive chemotherapy first, and 13 patients were randomized to receive observation first. Most patients (15 patients [63%]) were treated with either fluorouracil or capecitabine as single agent; 3 patients (13%) received doublet chemotherapy (leucovorin calcium [folinic acid], fluorouracil, and oxaliplatin or folinic acid, fluorouracil, and irinotecan hydrochloride), and bevacizumab was added to cytotoxic chemotherapy for 5 patients (21%). Fifteen patients were available to evaluate the primary end point of difference in tumor growth during treatment and observation periods. Tumor growth while receiving chemotherapy increased 8.4% (95% CI, 1.5% to 15.3%) from baseline but was not significantly different than tumor growth during observation (4.0%; 95% CI, -0.1% to 8.0%; P = .26). Of 18 patients who received any chemotherapy, none had an objective response (14 patients [77.8%] had stable disease; 4 patients [22.2%] had progressive disease). Median (range) OS was 53.2 (8.1 to 95.5) months, and there was no significant difference in OS between the observation-first group (76.0 [8.6 to 95.5] months) and the treatment-first group (53.2 [8.1 to 64.1] months; hazard ratio, 0.64; 95% CI, 0.16-2.55; P = .48). Patient-reported quality-of-life metrics identified that during treatment, patients experienced significantly worse fatigue (mean [SD] score, 18.5 [18.6] vs 28.9 [21.3]; P = .02), peripheral neuropathy (mean [SD] score, 6.67 [12.28] vs 38.89 [34.88]; P = .01), and financial difficulty (mean [SD] score, 8.9 [15.2] vs 28.9 [33.0]; P = .001) compared with during observation. In this prospective randomized crossover trial of systemic chemotherapy in patients with low-grade mucinous appendiceal adenocarcinoma, patients did not derive clinical benefit from fluorouracil-based chemotherapy, given there were no objective responses, no difference in OS when treatment was delayed 6 months, and no difference in the rate of tumor growth while receiving chemotherapy. ClinicalTrials.gov Identifier: NCT01946854.

Palliation of mucinous appendiceal neoplasms with peritoneal metastases with total abdominal colectomy.

Incomplete cytoreduction for mucinous appendiceal neoplasms is often required to temporarily alleviate symptoms. The surgical technology for this intervention may be complex and result in extensive morbidity and even mortality. Knowledgeable patient selection for this surgery is mandatory. A database was used to identify patients who had palliative surgery that included total abdominal colectomy (TAC). Clinical- and treatment-related variables were assessed for their impact on overall survival. Seventy-eight patients had an incomplete cytoreductive surgery (CRS) that included a TAC. The median survival was 2.5 years and the median follow-up was 2 years. Patients with symptoms of abdominal distention and ascites showed a reduced prognosis (p = 0.0254). The low-grade appendiceal mucinous neoplasms (LAMN) and mucinous appendiceal adenocarcinoma intermediate type (MACA-Int) grouped together showed a prolonged survival (p = 0.0003). MACA with positive lymph nodes showed a reduced survival (p = 0.0009) when compared to MACA patients without positive lymph nodes. A peritoneal cancer indexof 1-30 versus >30 and completeness of cytoreductionscore of 2 versus 3 were not significant. TAC with end ileostomy was used as a treatment option to provide palliation of patients having an incomplete CRS for appendiceal mucinous neoplasms. With LAMN or MACA-Int, median survival was 5.0 years. The surgery can be performed with a morbidity of 9.0% and mortality of 2.6%. Although not considered a palliative option in the past, these data suggest TAC may be used with acceptable results in this group of patients.

Secondary cytoreductive surgery for 86 patients with mucinous appendiceal adenocarcinoma.

After patients have a surgical procedure for a gastrointestinal cancer, follow-up is indicated. If cancer progression is documented in patients with mucinous appendiceal adenocarcinoma (MACA), a secondary cytoreductive surgery (SCRS) may be considered. In patients who had a prior complete cytoreductive surgery (CRS), variables associated with the index CRS and SCRS were extracted. These variables were statistically assessed for their impact on survival. Of 198 MACA patients, 86 (43.4%) had SCRS. The median follow-up was 5.0 years and the median survival was 7 years. Significant prognostic variables associated with the index CRS by univariant analysis was histopathologic grade of MACA-Intermediate (MACA-Int) as compared to other MACA histologic subtypes (p = 0.0164). Significant prognostic variables associated with the SCRS were bowel obstruction (p = 0.0149), interval of CRS to SCRS (p = 0.0059), and completeness of cytoreduction (p = 0.0014). In the analysis of variables from SCRS, the interval from CRS to SCRS ≤24 months indicates an aggressive biology of the disease. The CC score of complete versus incomplete decreased median survival from 11 to 4 years. A composite of these two variables allowed prediction of survival of 50% when patients showed these two favorable variables and only 9.1% when these variables were unfavorable.

A prospective randomized crossover trial of systemic chemotherapy in patients with low-grade mucinous appendiceal adenocarcinoma.

163 Background: Appendiceal adenocarcinoma is both a rare and heterogenous tumor, with marked contrast in the natural history of low-grade and high-grade tumors (5-year OS 68% for low-grade vs. 7% for high-grade). While low-grade appendiceal adenocarcinoma is primarily treated with surgical resection sometimes followed by hyperthermic intraperitoneal chemotherapy (HIPEC), many inoperable candidates are treated with systemic chemotherapy although there is no prospective data supporting this practice. The purpose of our study was to objectively evaluate the effectiveness of systemic chemotherapy in low-grade mucinous appendiceal adenocarcinoma. Methods: A randomized crossover trial of surgically unresectable low-grade (well differentiated) mucinous appendiceal adenocarcinoma was performed with patients randomized to either 6 months observation followed by 6 months of chemotherapy (physician’s choice), or initial chemotherapy followed by observation. In this way each patient would serve as their own control. Enrollment of 30 patients was planned to have complete 6- and 12-month tumor measurements for 24 patients, providing 80% power at 0.05 significance level to detect a 5.0% difference in change in tumor size as measured by peritoneal RECIST in observation vs. treatment periods. Results: The trial closed early due to slow accrual. A total of 24 patients were enrolled. The majority of patients were treated with either 5FU or capecitabine (n = 15, 63%), bevacizumab was added for 3 (13%), and 3 were treated with doublet chemotherapy (FOLFOX/FOLFIRI). 15 patients who completed both treatment and observation periods were available for the primary analysis, the mean difference in tumor size was -4.5% (95% CI: -12.6, 3.7), indicating a slight trend towards faster growth on treatment than observation. This difference was not statistically or clinically significant (8.4% growth on treatment vs. 4.0% observation, p=0.26). Of the 18 patients who received any chemotherapy during the study period, zero achieved an objective response, 14 (77.8%) had stable disease during the entire year of follow up, and 4 (12.2%) had progression on study. Patient reported quality of life metrics identified that fatigue (p=0.02), peripheral neuropathy (p=0.014), and financial difficulty (p=0.0013) were all significantly worse while on treatment. There was not a significant difference in rate of bowel obstruction between the treatment first vs. observation first arms (12.5%, (n=3) vs 8.3%, (n=2)). Conclusions: These data from a prospective, randomized crossover trial indicate that patients with low-grade mucinous appendiceal adenocarcinoma do not derive benefit from 5FU based chemotherapy but do incur toxicity. These data further highlight the unique biology of low-grade appendiceal cancer and demonstrates the need to identify novel systemic therapies for this patient population. Clinical trial information: NCT01946854 .

Use of distinct molecular signatures of appendiceal cancer subtypes to assess biomarker development.

189 Background: Appendiceal Neoplasms are diverse entities which have a variety of clinical presentations, histologic subtypes, biologic behavior, and patient outcomes. Advanced disease at initial diagnosis is not uncommon and therapeutic options are limited. This study aims to identify potential targets to develop epigenetics-based therapeutics/biomarkers. Methods: Archival (FFPE) specimens were collected from 25 patients with histologically confirmed and subtyped appendiceal neoplasia and 16 age-matched non-neoplastic controls. Four appendiceal neoplastic processes identified: Low grade appendiceal neoplasm (LAMN), pseudomyxoma peritonei (intra-peritoneal spread of LAMN), conventional-type adenocarcinoma and goblet cell adenocarcinoma. Gene expression profiling was performed using the HTG EdgeSeq Oncology Biomarker panel. Differentially expressed genes (DEGs) were selected with cut-off threshold FDR&lt;0.05 and analyzed using Qlucore Explorer and functional analyses via Ingenuity Pathway Analysis (IPA). Results: Four appendiceal neoplastic processes identified: pseudomyxoma peritonei (20%), low-grade appendiceal mucinous neoplasm (24%), adenocarcinoma (24%), and goblet cell adenocarcinoma (32%). Unsupervised hierarchical clustering identified 498 DEGs (424 up, 74 down) between all appendiceal cancer versus age-matched controls that showed enrichment in B-cell inflammatory signaling, senescence, cell cycle regulation, PI3K/AKT signaling, cell cycle checkpoint control pathways, and sets relating to NANOG in stem cell pluripotency (all p0.001). G1/S checkpoint, apoptosis, ATM, and PTEN signaling are downregulated (p0.001). TP53, E2F1, IL6, IFNG, TNF, and HGF (p0.001) regulated overlapping genes. Four-subgroups comparison found 67 DEGs involved in T-helper cell differentiation, immune-mediated apoptosis, T-cell fatigue, and PD1/PDL1 signaling to be dysregulated (p0.001). IFNG, FGF2, POU5F1, TNF, and MYC (p0.001) were upstream regulators. Conclusions: In this study, downregulated gene expressions in appendiceal cancers are related to cell proliferation and death control mechanisms, with a trend towards overexpression of inflammatory and cell cycle pathways. It is postulated that genes involved in these pathways are hypermethylated. More research is being undertaken on epigenetics-based biomarkers for diagnosis and prognosis. Given PI’s decades of experience in biomarker research, we aim to develop a "single blood test" to expand bedside monitoring alternatives that align with the National Cancer Moonshot Initiative to discover cancer early, when the likelihood of a cure is highest.

Antitumor activity of intraperitoneal (IP) paclitaxel to mucinous appendiceal adenocarcinoma in orthotopic patient-derived xenograft model.

151 Background: Appendiceal adenocarcinomas (AAs) are a rare and heterogeneous mix of tumors for which only few preclinical models exist for drug discovery. These tumors are commonly treated with chemotherapy like those for colorectal cancer despite clear evidence that the two cancers are distinctly different in their clinical behavior and molecular profiles. Taxanes such as paclitaxel (PTX) and docetaxel have been used in the systemic treatment of gastric cancer with peritoneal metastases. IP administration of PTX has been considered a promising treatment for eliminating peritoneal metastasis, as IP delivery of PTX can attain a higher drug exposure in the peritoneal cavity with reduced systemic toxicity because of high local concentrations over a long period of time due to its hydrophobic property. The purpose of this study was to test the efficacy of IP PTX treatment in orthotopic AA PDX models. Methods: AA tumors TM00351, PMP-2 and PMCA-3 were implanted in the peritoneal cavity of NSG mice. PDX models were treated with PTX (6.25, 12.5 or 25.0 mg/kg, IP) with weekly (3 weekly treatments and 1 week off, for two cycles) or biweekly (biweekly treatments for up to 12 weeks) schedule. The peritoneal tumor burden was monitored by MRI. Solid tumor size was evaluated by modified peritoneal Response Evaluation Criteria In Solid Tumors (mpRECIST) method using ImageJ software and mucinous tumor volume was quantified by OsiriX Lite software. Results: TM00351, taken from a high-grade tumor (Grade 3), formed mucin-rich solid tumors with mucinous ascites. PDX models PMP-2 (Grade 2) and PMCA-3 (Grade 3), both with GNASR201C mutation, had a mucinous phenotype similar to GNAS mutant appendiceal tumors in humans. Weekly 25.0 mg/kg of IP PTX treatment reduced AA tumor growth of TM00351 (77.9% reduction vs. control), PMP-2 (98.6% reduction vs. control), and PMCA-3 (85.6% reduction vs. control). Similarly, biweekly 25.0 mg/kg of IP PTX treatment was effective on PMCA-3 (66.2% reduction vs. control). Survival of PMCA-3 PDX mice was significantly improved by 12.5 mg/kg (p=0.0254, log-rank test) and 25.0 mg/kg (p=0.0038) of IP PTX. At 25.0 mg/kg IP PTX treatment induced 12.0% body weight loss of PMCA-3 PDX mice 1 week after the treatment. Lower doses of IP PTX treatment, 6.25 and 12.5 mg/kg, did not induce significant body weight loss or any noticeable adverse effects on mice. Comparing the efficacy of IV to IP administration, neither 6.25 or 12.5 mg/kg of IV PTX reduced growth of PMCA-3, 25.0 mg/kg of IV PTX was lethal to mice shortly after administration. Conclusions: IP PTX is a therapeutically active for mucinous AA tumors.

Secondary cytoreductive surgery for lymph node positive mucinous appendiceal neoplasms

BackgroundPatients who have surgery for a gastrointestinal cancer routinely have clinical and radiological tests in an effort to detect recurrent disease. If cancer progression is documented, additional surgery performed in a timely manner may prolong survival and help maintain an optimal quality of life. In mucinous appendiceal cancer patients a secondary cytoreductive surgery (SCRS) may be considered if recurrent disease is detected. MethodsIn patients with both lymph node metastases and peritoneal metastases from a mucinous appendiceal adenocarcinoma (MACA-LN) who had a prior complete cytoreductive surgery (CRS), the clinical- and treatment-related variables associated with the index CRS and the SCRS were extracted from a database and secured research files. These variables were statistically assessed for their impact on survival. ResultsTwelve of 39 lymph node positive patients (30.8%) had SCRS. The mean follow-up was 7.6 years and the median survival was 4.5 years. There were 4 males (33%) and median age was 44 years. Significant prognostic variables associated with improved survival with the index CRS by univariant analysis was the use of early postoperative intraperitoneal chemotherapy (EPIC) (p = 0.0469). For the SCRS, no significant prognostic variables, not even completeness of cytoreduction, were discovered. ConclusionsIn MACA-LN patients, improved survival with SCRS was shown as compared to patients who recurred but did not undergo SCRS. In this group of patients with an aggressive disease, if SCRS was possible it improved survival with long-term (greater than 5 years) follow-up.

Similar Survival Among All Subtypes of Mucinous Appendiceal Adenocarcinoma Except the Intermediate Subtype, Which Shows an Improved Survival.

Limited success in the management of mucinous appendiceal adenocarcinoma (MACA) has been reported. Cytoreductive surgery with perioperative intraperitoneal chemotherapy was used to treat a cohort of patients with peritoneal dissemination of MACA. The clinical and histopathologic variables were assessed for their impact on overall survival. The study analyzed 196 patients during a median follow-up period of 8 years. The patients had a median age was 46 years, a median survival of 12 years, and a mean survival of 12.4 years. Preoperative systemic chemotherapy and a high prior surgical score had a negative impact on prognosis. Survival was better for 37 patients (18.9%) with mucinous appendiceal adenocarcinoma-Intermediate (MACA-Int) histology than for 159 patients (81.1%) with MACA grade 1, 2, or 3, or signet ring cells (S) (p = 0.0004). Although MACA-1 and MACA-2 versus MACA-3 and MACA-S had a difference in survival of 63.9 versus 43.2 years at 5 years, with long-term follow-up evaluation, the differences in survival became insignificant (p = 0.5841). The histologic subtype of MACA-Int had a 10-year survival of 81.1%, which was markedly superior to that of MACA-1, -2, -3, or -S (32.7%). With long-term follow-up evaluation, MACA-1, -2, -3, and -S did not differ significantly in survival.

Molecular Classification of Appendiceal Adenocarcinoma.

Appendiceal adenocarcinomas (ACs) are rare, histologically diverse malignancies treated as colorectal cancers despite having distinct biology and clinical behavior. To guide clinical decision making, we defined molecular subtypes of AC associated with patient survival, metastatic burden, and chemotherapy response. A comprehensive molecular analysis was performed in patients with AC to define molecular subtypes. Associations between molecular subtype and overall survival, intraoperative peritoneal cancer index, and first-line chemotherapy response were assessed adjusting for histopathologic and clinical variables using multivariable Cox proportional hazards, linear regression, and logistic regression models. We defined distinct molecular lineages of mucinous appendiceal adenocarcinoma (MAAP) from co-occurring mutations in GNAS, RAS, and TP53. Of 164 MAAP tumors, 24 were RAS-mutant (mut) predominant (RAS-mut/GNAS-wild-type [wt]/TP53-wt) with significantly decreased mutations and chromosomal alterations compared with tumors with GNAS mutations (GNAS-mut predominant) or TP53 mutations (TP53-mut predominant). No patient with RAS-mut predominant subtype metastatic MAAP died of cancer, and overall survival in this subgroup was significantly improved compared with patients with GNAS-mut (P = .05) and TP53-mut (P = .004) predominant subtypes. TP53-mut predominant subtypes were highly aneuploid; increased tumor aneuploidy was independently (P = .001) associated with poor prognosis. The findings retained significance in patients with any metastatic AC. RAS-mut predominant metastases exhibited reduced peritoneal tumor bulk (P = .04) and stromal invasion (P < .001) compared with GNAS-mut or TP53-mut predominant tumors, respectively. Patients with RAS-mut predominant MAAP responded more to first-line chemotherapy (50%) compared with patients with GNAS-mut predominant tumors (6%, P = .03). AC molecular patterns identify distinct molecular subtypes: a clinically indolent RAS-mut/GNAS-wt/TP53-wt subtype; a chemotherapy-resistant GNAS-mut predominant subtype; and an aggressive, highly aneuploid TP53-mut predominant subtype. Each subtype exhibits conserved clinical behavior irrespective of histopathology.