A phase II study of niraparib in combination with EGFR inhibitor panitumumab in patients with advanced colorectal cancer

TPS269

Background: Panitumumab (Pmab) is a recombinant monoclonal antibody that binds specifically to the human epidermal growth factor receptor (EGFR), and is indicated for metastatic colorectal carcinoma (mCRC). EGFR inhibition induces synthetic lethality with poly ADP ribose polymerase inhibitors (PARPi) by attenuating DNA repair pathways. This susceptibility to PARPi-induced cell death by EGFR inhibition is associated with deficient Non-homologous end joining (NHEJ), and Homologous recombination (HR) mediated DNA repair and persistence of DNA damage. Furthermore, efficacy of PARPi (such as niraparib) is highly correlated with platinum sensitivity. Cancer cell sensitivity and resistance to both PARPi and platinum have been associated with loss and restoration of HR DNA repair, indicating similar mechanisms of anticancer activity and resistance. Platinum sensitivity in CRC could therefore predict for anticancer properties of PARPi when utilized in the setting of synthetic lethality. Combining PARP and EGFR inhibition has the potential to confer synergistic benefit, while ameliorating resistance mechanism to PARPi. This study aims to evaluate the activity of the combination of niraparib and Pmab in RAS wildtype (WT) mCRC. Methods: Eligible patients for the trial include advanced, RAS WT mCRC who have been intolerant of, progressed on, or failed at least one line of systemic chemotherapy. Those currently on first line oxaliplatin-containing regimen are allowed on the trial if they have remained stable or better (PR or CR) for at least 4 months on that line of treatment, and are being considered for maintenance therapy as standard of care. Patients must also be 18 years old, ECOG PS 0-1 and measurable disease per RECIST 1.1. A safety run-in cohort of 6 eligible patients, and additional 20 patients with the same inclusion criteria will be enrolled. Pmab dose - 6 mg/kg IV on days 1 & 15 of each 28-day cycle; Niraparib - 200mg or 300mg (based on body weight and platelet count) orally continuously. Primary endpoint: clinical benefit rate (CR +PR + SD). Biomarker analysis includes skin biopsies evaluated for p-Caspace-3, PARP, p-MAPK, Ki-67, and p27. The study was activated in Sept. 2019. Clinical trial information: NCT03983993.

Phase Ib trial of pembrolizumab and XL888 in patients with advanced gastrointestinal malignancies: Results of the dose-escalation phase

830

Background: XL888 is a selective inhibitor of heat shock protein 90 (HSP90). It modulates several oncogenic signaling pathways, and the tumor microenvironment. In preclinical models, XL888 potentiates efficacy of PD-1 inhibition. We report the results of the dose escalation (DE) portion of a phase Ib trial of combined XL888 and pembrolizumab (P) in advanced gastrointestinal adenocarcinomas. Methods: XL888 was administered orally (PO) in three dose levels of 45 (DL1), 90 (DL2), 60 (only if DLT on DL2) mg twice weekly with P 200 mg IV on day 1, in 21-day cycles. Eligible patients included stage IV or locally advanced unresectable gastrointestinal adenocarcinomas with at least one prior therapy (patients with colorectal (CRC) adenocarcinoma must have received oxaliplatin, irinotecan, and fluoropyrimidine), age ≥18 years, ECOG PS 0-1, adequate organ function, no prior anti-PD-1 or anti-PD-L1 agent. The primary endpoint was recommended phase II dose (RP2D), while secondary endpoints included safety and tolerability. Pre-treatment and on-treatment correlative peripheral blood specimens were collected. Results: A total of 14 patients were enrolled in the DE phase. 9 male, median age 66.5. Diagnoses included CRC (6), pancreatic adenocarcinoma (5), biliary tract cancer (1), ampullary (1), and duodenal (1). Two patients were ineligible for assessing the primary endpoint (DL2) due to biliary stent obstruction and sepsis. One DLT (grade 3 autoimmune hepatitis) was observed on DL2. We enrolled three patients on DL3. Five additional patients were subsequently enrolled on DL2 with no additional DLT. Three patients (1 duodenal, 2 CRC) had prolonged stable disease (6, 9 and 15 cycles). The most common treatment-related toxicities included autoimmune hepatitis (G3; n = 1), retinopathy (G2; n = 2), nausea (G2; n = 1), constipation (G2; n = 1), and diarrhea (G2; n = 3). Conclusions: The XL888 and pembrolizumab combination had an acceptable safety profile and the RP2D of XL888 was 90 mg twice weekly combined with P 200 mg, every 3 weeks. The dose expansion portion and a robust series of immunologic correlative laboratory studies for this study is ongoing. Clinical trial information: NCT03095781.

The impact of inflammatory biomarkers, BMI, and sarcopenia on survival in advanced hepatocellular carcinoma treated with immunotherapy

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Background: Sarcopenia and inflammation are independently associated with worse survival in cancer patients. This study aims to determine the impact of inflammatory biomarkers, BMI and sarcopenia on survival in advanced hepatocellular carcinoma (HCC) patients treated with immunotherapy. Methods: We performed a retrospective review of advanced HCC patients treated with immunotherapy-based therapies at Winship Cancer Institute between 2015 and 2019. Baseline computed tomography and magnetic resonance imaging scans were collected at mid-L3 level, assessed for skeletal muscle density using SliceOmatic (TomoVision, version 5.0) and converted to skeletal muscle index (SMI) by dividing it by height (m)2. Gender-specific sarcopenia was defined by median value of SMI. The optimal cut for continuous inflammation biomarker was determined by bias-adjusted log-rank test. Overall Survival (OS) was set as primary outcome and Cox proportional hazard model was performed. Results: 57 patients were included; 77.2% male, 52.6% Caucasian, 58.5% ECOG PS 0-1, 80.7% Child Pugh A. Treatment was second line and beyond in 71.9%. The median follow-up time was 6 months. Sarcopenia cut-off for males and females was SMI of 43 and 39, respectively. 49.1% of patients had sarcopenia. Median OS was 5 vs. 14.3 months in sarcopenic vs. non-sarcopenic patients (p=0.054). Median OS was 5 and 17.5 months in patients with BMI <25 and BMI ≥25 respectively (p=0.034). Median OS was 3.6 and 14.3 months for patients with neutrophil to lymphocyte ratio (NLR) ≥ 5.15 vs. NLR < 5.15 (p<0.001). In multivariable Cox regression model, higher baseline NLR was associated with worse OS (HR: 4.17, 1.52-11.39, p=0.005). Gender specific sarcopenia showed a trend of worse OS (HR: 1.71, 0.73-4.00, p=0.215) but was not statistically significant. BMI<25 was associated with worse OS (HR: 2.73, 1.15-6.53, p=0.023). In the association with PFS, neither baseline BMI nor gender specific sarcopenia showed statistical significance. Conclusions: Baseline BMI and NLR may predict OS after immunotherapy treatment. After controlling for baseline Child Pugh Score and NLR, gender specific sarcopenia was not associated with OS significantly.

A Phase I Study of Safety, Pharmacokinetics, and Pharmacodynamics of Concurrent Everolimus and Buparlisib Treatment in Advanced Solid Tumors

PURPOSE

Concurrent inhibition of mTOR and PI3K led to improved efficacy in preclinical models and provided the rationale for this phase I study of everolimus and buparlisib (BKM120) in patients with advanced solid tumor.

PATIENTS AND METHODS

We used the Bayesian Escalation with Overdose Control design to test escalating doses of everolimus (5 or 10 mg) and buparlisib (20, 40, 60, 80, and 100 mg) in eligible patients. Pharmacokinetic assessment was conducted using blood samples collected on cycle 1, days 8 and 15. Pharmacodynamic impact on mTOR/PI3K pathway modulation evaluated in paired skin biopsies collected at baseline and end of cycle 1.

RESULTS

We enrolled 43 patients, median age of 63 (range, 39-78) years; 25 (58.1%) females, 35 (81.4%) Caucasians, and 8 (18.6%) Blacks. The most frequent toxicities were hyperglycemia, diarrhea, nausea, fatigue, and aspartate aminotransferase elevation. Dose-limiting toxicities observed in 7 patients were fatigue (3), hyperglycemia (2), mucositis (1), acute kidney injury (1), and urinary tract infection (1). The recommended phase II dose (RP2D) for the combination was established as everolimus (5 mg) and buparlisib (60 mg). The best response in 27 evaluable patients was progressive disease and stable disease in 3 (11%) and 24 (89%), respectively. The median progression-free survival and overall survival were 2.7 (1.8-4.2) and 9 (6.4-13.2) months. Steady-state pharmacokinetic analysis showed dose-normalized maximum concentrations and AUC values for everolimus and buparlisib in combination to be comparable with single-agent pharmacokinetic.

CONCLUSIONS

The combination of everolimus and buparlisib is safe and well-tolerated at the RP2D of 5 and 60 mg on a continuous daily schedule.

Combined Effect of Sarcopenia and Systemic Inflammation on Survival in Patients with Advanced Stage Cancer Treated with Immunotherapy

Background

Sarcopenia and inflammation have been associated with poor survival in patients with cancer. We explored the combined effects of these variables on survival in patients with cancer treated with immunotherapy.

Methods

We performed a retrospective review of 90 patients enrolled on immunotherapy‐based phase I clinical trials at Emory University from 2009 to 2017. Baseline neutrophil‐to‐lymphocyte ratio, monocyte‐to‐lymphocyte ratio, and platelet‐to‐lymphocyte ratio (PLR) were used as surrogates of inflammation. The skeletal muscle index (SMI) was derived from the skeletal muscle density calculated from baseline abdominal computed tomography images. Optimal cutoffs for continuous inflammation biomarkers and SMI were determined by bias‐adjusted log‐rank test. A four‐level risk stratification was used to create low‐risk (PLR <242 and nonsarcopenic), intermediate‐risk (PLR <242 and sarcopenic), high‐risk (PLR ≥242 and nonsarcopenic), and very‐high‐risk (PLR ≥242 and sarcopenic) groups with subsequent association with survival.

Results

Most patients (59%) were male, and the most common cancers were melanoma (33%) and gastrointestinal (22%). Very high‐risk, high‐risk, and intermediate‐risk patients had significantly shorter overall survival (hazard ratio [HR], 8.46; 95% confidence interval [CI], 2.65–27.01; p < .001; HR, 5.32; CI, 1.96–14.43; p = .001; and HR, 4.01; CI, 1.66–9.68; p = .002, respectively) and progression‐free survival (HR, 12.29; CI, 5.15–29.32; p < .001; HR, 3.51; CI, 1.37–9.02; p = .009; and HR, 2.14; CI, 1.12–4.10; p = .022, respectively) compared with low‐risk patients.

Conclusion

Baseline sarcopenia and elevated inflammatory biomarkers may have a combined effect on decreasing survival in immunotherapy‐treated patients in phase I trials. These data may be immediately applicable for medical oncologists for the risk stratification of patients beginning immunotherapeutic agents.

Implications for Practice

Sarcopenia and inflammation have been associated with poor survival in patients with cancer, but it is unclear how to apply this information to patient care. The authors created a risk‐stratification system that combined sarcopenia and platelet‐to‐lymphocyte ratio as a marker of systemic inflammation. The presence of sarcopenia and systemic inflammation decreased progression‐free survival and overall survival in our cohort of 90 patients who received immunotherapy in phase I clinical trials. The data presented in this study may be immediately applicable for medical oncologists as a way to risk‐stratify patients who are beginning treatment with immunotherapy.

The interaction between chronic inflammation and body composition is particularly important in the era of immunotherapy, considering that immune checkpoint inhibitors rely on the host immune system for their efficacy. This article reports on the combined effects of inflammation and sarcopenia on clinical outcomes in patients with solid tumors treated with immunotherapy‐based regimens.

Analysis of racial disparities in the treatment and outcomes of colorectal cancer in young adults

BACKGROUND

The incidence of colorectal cancer (CRC) in young adults is increasing. Minority populations with CRC are known to have worse survival outcomes. The aim of this study is to evaluate adults under age 50 years with CRC by race and ethnicity.

METHODS

Data were obtained from all US hospitals that contributed to the National Cancer Database (NCDB) between 2004 and 2013. Univariate and multivariable testing was done to identify factors associated with patient outcome. Kaplan-Meier analysis and Cox proportional hazards models were used for association between patient characteristics and survival.

RESULTS

A total of 83,449 patients between 18 and 50 years of age were identified. Median age was 45 years (SD ± 6), with male preponderance (53.9%). 72% were non-Hispanic Whites (NHW), Blacks (AA) were 15.1% and Hispanics (who did not identify as Blacks) were 8.3% of the study population. Distribution across stages IIV was 15.6%, 22.4%, 33.9% and 27% consecutively. 41.8% of NHW and 28.4% of AA had rectal cancers (p < 0.001). Despite equally receiving standard of care (SOC) as per national guidelines, AA had significantly lower 5-year survival rates (58.8%) compared to Hispanics (64.8%) and NHW (66.9%; HR 1.42; 1.38-1.46; p < 0.001). Furthermore, NHW (HR 0.85; 0.81-0.88; p < 0.001) and Hispanics (HR 0.75; 0.70-0.79; p < 0.001) were more likely to benefit from chemotherapy compared to AA. SOC utilization was associated with improved survival across all racial groups, especially in AA (HR 0.64; 0.60-0.69; p < 0.001).

CONCLUSION

Despite comparable rates of SOC utilization, AA young adults had worse survival outcomes compared to other races. More colon (compared to rectal) cancers in AA may have contributed to their worse outcomes.

Blood-Based Next-Generation Sequencing Analysis of Appendiceal Cancers

BACKGROUND

Appendiceal cancers (ACs) are rare. The genomic landscape of ACs has not been well studied. The aim of this study was to confirm the feasibility of next-generation sequencing (NGS) using circulating tumor DNA (ctDNA) in ACs and characterize common genomic alterations.

MATERIALS AND METHODS

Molecular alterations in 372 plasma samples from 303 patients with AC using clinical-grade NGS of ctDNA (Guardant360) across multiple institutions were evaluated. Test detects single nucleotide variants in 54-73 genes, copy number amplifications, fusions, and indels in selected genes.

RESULTS

A total of 303 patients with AC were evaluated, of which 169 (56%) were female. Median age was 56.8 (25-83) years. ctDNA NGS testing was performed on 372 plasma samples; 48 patients had testing performed twice, 9 patients had testing performed three times, and 1 patient had testing performed four times. Genomic alterations were defined in 207 (n = 207/372, 55.6%) samples, and 288 alterations were identified excluding variants of uncertain significance and synonymous mutations. Alterations were identified in at least one sample from 184 patients; TP53-associated genes (n = 71, 38.6%), KRAS (n = 33, 17.9%), APC (n = 14, 7.6%), EGFR (n = 12, 6.5%), BRAF (n = 11, 5.9%), NF1 (n = 10, 5.4%), MYC (n = 9, 4.9%), GNAS (n = 8, 4.3%), MET (n = 6, 3.3%), PIK3CA (n = 5, 2.7%), and ATM (n = 5, 2.7%). Other low-frequency but clinically relevant genomic alterations were as follows: AR (n = 4, 2.2%), TERT (n = 4, 2.2%), ERBB2 (n = 4, 2.2%), SMAD4 (n = 3, 1.6%), CDK4 (n = 2, 1.1%), NRAS (n = 2, 1.1%), FGFR1 (n = 2, 1.1%), FGFR2 (n = 2, 1.1%), PTEN (n = 2, 1.1%), RB1 (n = 2, 1.1%), and CDK6, CDKN2A, BRCA1, BRCA2, JAK2, IDH2, MAPK, NTRK1, CDH1, ARID1A, and PDGFRA (n = 1, 0.5%).

CONCLUSION

Evaluation of ctDNA is feasible among patients with AC. The frequency of genomic alterations is similar to that previously reported in tissue NGS. Liquid biopsies are not invasive and can provide personalized options for targeted therapies in patients with AC.

IMPLICATIONS FOR PRACTICE

The complexity of appendiceal cancer and its unique genomic characteristics suggest that customized combination therapy may be required for many patients. Theoretically, as more oncogenic pathways are discovered and more targeted therapies are approved, customized treatment based on the patient's unique molecular profile will lead to personalized care and improve patient outcomes. Liquid biopsies are noninvasive, cost-effective, and promising methods that provide patients with access to personalized treatment.

In-hospital 30-day mortality for older patients with pancreatic cancer undergoing pancreaticoduodenectomy

OBJECTIVE

Surgical resection remains the only potentially curative therapy for pancreatic ductal adenocarcinoma (PDAC). There is paucity of literature about morbidity and mortality in older patients with PDAC undergoing pancreaticoduodenectomy. This retrospective analysis evaluates the in-hospital 30-day mortality of this population utilizing the Nationwide Inpatient Sample (NIS) database.

SUBJECTS AND METHODS

All US patients hospitalized for pancreaticoduodenectomy (Whipple procedure) were included. Data was obtained from the NIS provided by the Agency for Healthcare Research and Quality. Pancreaticoduodenectomy diagnoses were identified using Clinical Classifications Software codes based on ICD-9 between 2007 and 2010. Univariable and multivariable analyses were performed using the logistic model, weighted chi-square test, and generalized linear model.

RESULTS

A total of 6149 patient discharges for pancreaticoduodenectomy were identified. Mean age was 64.9 years (SD ± 12.3); 21% of patients were ≥ 76 years of age. Majority were White (N = 5257, 77.9%) with a male:female ratio of 1. Patients aged 76 and older (OR: 1.76; 1.36-2.28; p < .001), Hispanics (OR: 1.40; 0.92-2.13; p = .12), and high comorbidity score (OR: 5.70; 3.44-9.46; p < .001) were found to be associated with a higher risk of 30-day in-hospital mortality. In the multivariable analysis, advanced age (>76) remained a significant predictor of longer in-hospital length of stay (OR: 1.09; 1.04-1.14; p < .001) and 30-day in-hospital mortality (OR 1.46; 1.07-2.00; p = .016). The 30-day in-hospital mortality rate for all patients across all years was 3.24%, for patients >76 years 4.11% and for patients <76 years 2.77%. Patients who underwent surgery at teaching hospitals (OR: 0.61; 0.42-0.88; p = .008) had a lower risk of 30-day in-hospital mortality compared to non-teaching hospitals.

CONCLUSION

In-hospital 30 day mortality was higher in selected older patients with PDAC undergoing pancreaticoduodenectomy. Mortality was lower at high volume and teaching centers. Further stringent selection criteria are needed to decrease mortality in the older population.

Immune checkpoint inhibitors for the treatment of MSI-H/MMR-D colorectal cancer and a perspective on resistance mechanisms

Metastatic colorectal cancer (CRC) with a mismatch repair-deficiency (MMR-D)/microsatellite instability-high (MSI-H) phenotype carries unique characteristics such as increased tumour mutational burden and tumour-infiltrating lymphocytes. Studies have shown a sustained clinical response to immune checkpoint inhibitors with dramatic clinical improvement in patients with MSI-H/MMR-D CRC. However, the observed response rates range between 30% and 50% suggesting the existence of intrinsic resistance mechanisms. Moreover, disease progression after an initial positive response to immune checkpoint inhibitor treatment points to acquired resistance mechanisms. In this review article, we discuss the clinical trials that established the efficacy of immune checkpoint inhibitors in patients with MSI-H/MMR-D CRC, consider biomarkers of the immune response and elaborate on potential mechanisms related to intrinsic and acquired resistance. We also provide a perspective on possible future therapeutic approaches that might improve clinical outcomes, particularly in patients with actionable resistance mechanisms.

Clinical Outcomes of Small Bowel Adenocarcinoma

BACKGROUND

Small bowel adenocarcinomas (SBAs) are rare tumors. Management of SBA is extrapolated from colorectal cancer treatments. Recent evidence suggests that the biology and molecular features of SBA differ from colorectal cancer. The aim of this study was to evaluate the management and outcome of SBA patients. PATIENTS AND METHODS: The National Cancer Data Base (NCDB) was queried for patients with SBA between 2004 and 2013 using ICD-O-3 histology code 8140/3 and topography codes C17.0, C17.1, C17.2, C17.8, and C17.9. Univariate and multivariate survival analyses were conducted to analyze the association between SBA location and overall survival (OS) stratified by stage. Treatment outcomes of surgery, radiation, and systemic therapy were compared.

RESULTS

A total of 7954 SBA patients were identified; duodenum (D) 4607 (57.9%), jejunum (J) 1241 (15.6%), ileum (I) 857 (10.8%), and unspecified 1249 (15.7%). A total of 53.6% patients were male, and 76.6% white. Median age was 66 years. D mostly presented as stage IV disease (37.6%), J as stage II (34.5%) and IV disease (33.8%), and I as stage II (32.2%) and III (30.3%) disease (P < .001). Grade distribution was similar among D, J, and I; the majority were moderately differentiated (40.8%-55.0%), followed by poorly differentiated (30.9%-35.8%) and well differentiated (6.0%-12.4%) (P < .001). D underwent surgery (50.2%) less often than J (90.8%) and I (94.5%) (P < .001). Adjuvant radiation was provided in 8.5% of D, 2.6% of J, and 2.1% of I (P < .001). Adjuvant chemotherapy was provided in 21.9% of D, 50.2% of J, and 42.0% of I (P < .001). The rate of adjuvant chemotherapy was the highest in patients with stage III SBA, and was as follows: D (43.4%), J (65.4%), and I (63.6%) (P < .001). In univariate and multivariate analyses of all patients, adjuvant chemotherapy was associated with improved OS in stage II-III SBA patients. J had the best 5-year OS rate (42.0%; 95% confidence interval, 38.8-45.1, P < .001), and D had the worst (23.0%; 95% confidence interval, 21.6-24.2, P < .001). In multivariate analysis stratified by stage, chemotherapy was associated with improved OS in patients with stage II-IV SBA.

CONCLUSION

Most SBA patients present with stage IV disease. D underwent surgery less often than J and I. Stage II and III D received adjuvant chemotherapy less often compared to stage II and III J and I. Adjuvant chemotherapy was associated with improved OS in patients with stage II-III disease. J had the best 5-year OS rate, and D had the worst.

Sites of metastasis and association with clinical outcome in advanced stage cancer patients treated with immunotherapy

Background

Selecting the appropriate patients to receive immunotherapy (IO) remains a challenge due to the lack of optimal biomarkers. The presence of liver metastases has been implicated as a poor prognostic factor in patients with metastatic cancer. We investigated the association between sites of metastatic disease and clinical outcomes in patients receiving IO.

Methods

We conducted a retrospective review of 90 patients treated on IO-based phase 1 clinical trials at Winship Cancer Institute of Emory University between 2009 and 2017. Overall survival (OS) and progression-free survival (PFS) were measured from the first dose of IO to date of death or hospice referral and clinical or radiographic progression, respectively. Clinical benefit (CB) was defined as a best response of complete response (CR), partial response (PR), or stable disease (SD). Univariate analysis (UVA) and Multivariate analysis (MVA) were carried out using Cox proportional hazard model or logistic regression model. Covariates included age, whether IO is indicated for the patient’s histology, ECOG performance status, Royal Marsden Hospital (RMH) risk group, number of metastatic sites, and histology.

Results

The median age was 63 years and 53% of patients were men. The most common histologies were melanoma (33%) and gastrointestinal cancers (22%). Most patients (73.3%) had more than one site of distant metastasis. Sites of metastasis collected were lymph node (n = 58), liver (n = 40), lung (n = 37), bone (n = 24), and brain (n = 8). Most patients (80.7%) were RMH good risk. Most patients (n = 62) had received 2+ prior lines of systemic treatment before receiving IO on trial; 27 patients (30.0%) received prior ICB. Liver metastases were associated with significantly shorter OS (HR: 0.38, CI: 0.17–0.84, p = 0.017). Patients with liver metastasis also trended towards having shorter PFS (HR: 0.70, CI: 0.41–1.19, p = 0.188). The median OS was substantially longer for patients without liver metastases (21.9 vs. 8.1 months, p = 0.0048).

Conclusions

Liver metastases may be a poor prognostic factor in patients receiving IO on phase 1 clinical trials. The presence of liver metastases may warrant consideration in updated prognostic models if these findings are validated in a larger prospective cohort.

Clinical outcomes of rare hepatocellular carcinoma variants compared to pure hepatocellular carcinoma

Background

HCC variants are rare primary hepatic tumors. The aim of this study is to compare clinical characteristics and outcomes of HCC variants with pure HCC.

Methods

Patients diagnosed between 2004 and 2013 with ICD-O-3 8180/3 and 8170/3-8175/3 were identified from the National Cancer Database. Univariate and multivariate survival analyses were conducted to analyze the association between histology and overall survival (OS).

Results

80,280 patients were identified; pure HCC 78,461 (97.7%), fibrolamellar (FLHCC) 310 (0.4%), scirrhous 161 (0.2%), spindle cell 72 (0.1%), clear cell 487 (0.6%), pleomorphic 23 (0.0%), and combined HCC and cholangiocarcinoma (mixed HCC) 766 (1.0%). 76.7% were male and 72% Caucasian. Liver transplant was performed in 10.1% of pure HCC, 14.5% of mixed HCC, 16.2% of scirrhous, 6.9% of spindle cell, 8.8% of clear cell, 8.7% of pleomorphic, and 3.2% of FLHCC (p<0.001). Pure HCC (10.6%) underwent surgical resection without transplant less often than variants except for scirrhous (9.9%) (p<0.001). More than a third of patients in each histological type received chemotherapy. FLHCC had the best 5-year OS (38.7%), spindle cell and pleomorphic had the worst (9.6% and 13.0%). In multivariate analysis stratified by histology variants, chemotherapy was associated with improved OS in all histologies except for scirrhous and pleomorphic HCC.

Conclusion

HCC variants underwent surgical resection more often than pure HCC. FLHCC had the best 5-year OS. Liver transplant was commonly performed in HCC variants.

Abstract 4074: Heat shock protein 90 inhibitors alter pancreatic stellate cell cytokine production and enhances the efficacy of immune checkpoint blockade in pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) has a prominent fibrotic stroma, which is a result of interactions between tumor, immune and pancreatic stellate cells (PSC). Prior work from our laboratory has defined a role for stroma-derived cytokines such as IL-6 as a significant barrier restraining immunity against PDAC. Our group is pursuing novel approaches to target pathways in the tumor microenvironment (TME), in an effort to improve access of effector immune cells to PDAC and response to immunotherapy. Heat shock protein-90 (Hsp90), is a chaperone protein and a versatile target in pancreatic cancer. Hsp90 regulates a diverse array of cellular processes of relevance to both the tumor and the immune system. However, to date the role of Hsp90 in PSC has not been explored in detail. We hypothesize that targeting Hsp90 can modulate the TME, through its ability to target inflammatory signaling and cytokine production by PSC and enhance the efficacy of immunotherapy. Treatment of immortalized and primary patient PSC with the Hsp90 inhibitor XL888 led to decreased IL-6 at the transcript and protein level in vitro. XL888 directly limited PSC growth, and reduced expression of alpha-SMA, Jak/STAT and MAPK signaling intermediates as determined via immunoblot. Combined therapy with XL888 and anti-PD-1 was efficacious in C57BL/6 mice bearing syngeneic subcutaneous (Panc02) or orthotopic (KPC-Luc) tumors, as compared to treatment with either agent alone. The treatment was well-tolerated, with no difference in body weight observed in either model. Laboratory studies are assessing immune and stromal biomarkers to define the impact on PSC, cytokines and T-cell biomarkers in the TME. Finally, we have completed the dose escalation phase of a Phase Ib/II clinical trial of XL888 (Hsp90i) and pembrolizumab (anti-PD-1) at our institution. Expansion cohorts of patients with metastatic pancreatic cancer (n=16) or colorectal cancer (n=16) are now accruing, with paired biopsy and peripheral blood samples to address the impact of Hsp90 inhibition on anti-PD-1 mediated T cell proliferation, cytokine production, and PSC-derived cytokine signatures.

Citation Format: Mohammad Zaidi, Yuchen Zhang, Michael B. Ware, Matthew R. Farren, Hannah Komar, Brian Olson, Ganji P. Nagaraju, Mehmet Akce, Olatunji Alese, Shishir Maithel, Juan Sarmiento, Walid Shaib, Christina Wu, Bassel El-Rayes, Gregory B. Lesinski. Heat shock protein 90 inhibitors alter pancreatic stellate cell cytokine production and enhances the efficacy of immune checkpoint blockade in pancreatic cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4074.

Analysis of age, tumor-sidedness, and mismatch repair (MMR) genes with response to immune checkpoint inhibitors (ICIs) in MMR-deficient (dMMR) colorectal cancer (CRC) patients (pts): A multi-institutional study

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Background: ICIs induce durable responses in dMMR CRC pts with overall response rates (ORR) of 30-50%. Even though the loss of expression of any MMR gene predicts ICIs response, it is unknown if ORRs are similar across all MMR genes (MLH1, PMS2, MSH2, and MSH6). In this study, we analyzed the impact of each specific MMR gene loss and clinical characteristics of pts with best response to ICIs. Methods: Pts were eligible if they had confirmed dMMR CRC by IHC or microsatellite instability-high (MSI-H) by PCR, and received ICIs between 01/01/2012 and 10/01/2018 at Winship Cancer Institute of Emory University, Mayo Clinic or Vanderbilt University Medical Center. Due to the pattern of frequent concurrent loss and functional dependency, the groups were categorized as MLH1 ±PMS2 vs. MSH2 ±MSH6. Cox proportional hazard model and Fisher’s exact test were used for the best response and the distribution of variable among the subgroups. Results: A total of 45 pts with dMMR CRC were identified. ORRs in MLH1 ±PMS2 and MSH2 ±MSH6 groups were 68% and 57.1% respectively without statistical difference (Table). Pts with age < 50 and 50-65 years old had better ORRs compared to pts with age >65 (58.3%, 85.7% and 42.1% respectively, P=0.036). Left-sided tumors had a trend toward higher ORRs compared to right-sided tumors (83.3% vs 51.5% P=0.086). Gender and BRAF status were not predictors of response. BRAF mutations were more common in right-sided tumors (29.6% vs 11.1% respectively) and in older patients. Conclusions: Our data suggest that MSI-H CRC pts aged 50-65 treated with ICIs, have improved ORR compared to pts > 65; pts with left-sided tumors have a trend toward improved ORR compared to those with right sided tumors. [Table: see text]

Role of resection of the primary in metastatic well/intermediate-differentiated neuroendocrine tumor (NET)

e15693

Background: Resection of the primary tumor in metastatic neuroendocrine tumor (NET) is controversial. The aim of this study is to evaluate survival outcomes and identify prognostic variables of surgical resection of the primary tumor in metastatic NET patients. Methods: Data were obtained from all US hospitals that contributed to the National Cancer Database (NCDB) between 2004 and 2013. Chi-square and ANOVA tests were done to identify factors associated with surgical modality. Univariate and multivariate cox proportional hazards models were used for association between patient characteristics and survival. Kaplan-Meier curves were generated and log-rank tests conducted to compare the survival difference of patient characteristics. Results: A total of 2,361 patients between 18 and 90 years of age with stage IV well/intermediate-differentiated NET were identified. The mean age was 62.1 years (SD±13), with an equal male to female ratio (50.0%). Majority of NET primaries were in the small intestine (33.0%), pancreas (26.3%), and lung (24.4%). The majority were well differentiated tumors (69.6%) and 42.5% of patients underwent surgery at the primary site. On multivariate analysis total surgical resection of the primary (HR 0.44; 0.22-0.90; p < 0.001), female sex, year of diagnosis 2010-2014, negative surgical margin, Charlson-Deyo score < 2, and age < 51 years at diagnosis were associated with better overall survival (OS). Conclusions: Resection of the primary in stage IV well/intermediate-differentiated NET was associated with improved 5-year OS compared to patients with no surgery in small intestine (60.1% vs 44.2%), lung (70.0% vs 20.2%), and pancreas tumors (59.3% vs 30.6%).

Blood-based next-generation sequencing analysis of neuroendocrine tumors

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Background: Neuroendocrine tumors (NET) comprise around 2% of all malignant tumors of the gastrointestinal system. The genomic landscape of NET has not been well studied. The aim of this study was to confirm the feasibility of next generation sequencing (NGS) using ctDNA in NET and characterize common alterations in the genomic profile. Methods: Molecular alterations in 114 plasma samples from 114 patients with NET using clinical-grade NGS of ctDNA (Guardant360Ò) across multiple institutions were evaluated. The test detects single nucleotide variants in 54-73 genes, copy number amplifications, fusions, and indels in selected genes. Results: A total of 114 NET patients were evaluated, of which 64 (56.1%) were female. Mean age was 59.7 years with a range between 23-89 years. ctDNA NGS testing was performed on 114 plasma samples; 1 patient had testing performed twice. Genomic alterations were defined in 94 (n = 94/114, 82.5%) samples with a total of 289 alterations identified after excluding variants of uncertain significance (VUSs) and synonymous mutations. Alterations were identified in at least one sample from 83 patients; TP53 associated genes were most commonly altered (n = 83/289, 28.7%), followed by KRAS (n = 22, 7.6%), PI3CA (n = 15, 5.2%), CCNE1 (n = 15, 5.2%), BRAF (n = 13, 4.5%), MYC (n = 12, 4.1%), ERBB2 (n = 11, 3.8%), APC (n = 10, 3.5%), EGFR (n = 10, 3.5%), MET (n = 10, 3.5%), PTEN (n = 9, 3.1%), RB1 (n = 9, 3.1%), CDK6 (n = 7, 2.4%), AR (n = 5, 1.7%), ARID1A (n = 5, 1.7%), FGFR1 (n = 5, 1.7%), and PDGFRA (n = 5, 1.7%). Other genomic alterations of low frequency, but clinical relevance included: CDK4 (n = 4, 1.3%), NF1 (n = 4, 1.3%), RAF1 (n = 4, 1.3%), GNAS (n = 3, 1.0%), KIT (n = 3, 1.3%), BRCA2 (n = 2, 0.7%), CCND2 (n = 2, 0.7%), CTNNB1 (n = 2, 0.7%), JAK2 (n = 2, 0.7%), NRAS (n = 2, 0.7%), SMAD4 (n = 2, 0.7%), and TERT (n = 2, 0.7%). Alterations in AKT1, ALK, ATM, BRCA1, CCND1, CDKN2A, FGFR2, MTOR, RHOA, SMO and STK11 were all reported once (n = 1, 0.3%). Conclusions: Evaluation of ctDNA is feasible among individuals with NET. Liquid biopsies are not invasive and can provide personalized options for targeted therapies in NET patients.

Perioperative therapy in patients with metastatic colorectal cancer

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Background: Knowledge about perioperative systemic therapy in metastatic colorectal cancer (mCRC) is limited. We aim to describe the nationwide pattern of use and survival outcomes of patients with mCRC treated with surgical resection. Methods: Data were obtained from all US hospitals that contributed to the National Cancer Database (NCDB) between 2004 and 2013. Univariate and multivariate analyses was done to identify factors associated with patient outcome. Results: A total of 61,940 patients with stage IV CRC older than 18 years were identified. Mean age was 63.4 years (SD±14), with a male preponderance (54.8%). About 80% were Caucasian and 69.9% had colon cancer. Compared to medical treatment only, resection of both primary and metastatic sites (13.5%; HR 0.40; 0.37-0.44; p < 0.001), or primary site resection alone (49.2%; HR 0.52; 0.48-0.56; p < 0.001) were associated with improved overall survival (OS). Other co-variates associated with improved survival included younger age group, year of diagnosis (2009-2013), colon tumor location, and < 3 metastatic sites (Table). Five-year OS for resection of primary and metastatic site (28.2%) was higher than for primary site resection alone (14.9%) or no surgical treatment (4.7%). Conclusions: Resection of metastatic sites or primary tumor was associated with improved survival in patients with stage IV CRC.[Table: see text]

Genomic alterations in appendiceal carcinoma using circulating DNA

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Background: Appendiceal cancers (AC) comprise around 0.5% of all gastrointestinal neoplasia. The genomic landscape of AC has not been well studied. The yield of circulating tumor DNA (ctDNA) from the plasma of patients with AC has not been reported. The aim of this study is to confirm the feasibility of NGS using ctDNA and characterize common alternations in the genomic profile of AC. Methods: The molecular alterations in 372 plasma samples from 303 patients with AC using clinical-grade NGS of ctDNA (Guardant 360) across multiple institutions, was evaluated. The test detects single nucleotide variants in 54 -73 genes, copy number amplifications, fusions, and indels in selected genes. Results: A total of 303 AC patients were evaluated; 169 female (56%). Median age was 56.8 (range: 25-83). ctDNA NGS testing was done on 372 plasma samples; 48 patients had testing performed twice, 9 three times, and 1 was tested four times. Genomic alterations were defined in 207 (55.6%) samples with a total of 288 alterations identified after excluding variants of uncertain significance (VUSs) and synonymous mutations. TP53 associated genes were most commonly altered (n = 96, 33.3%), followed by KRAS (n = 41, 14.2%), APC (n = 19, 6.6%), EGFR (n = 15, 5.2%), BRAF (n = 13, 4.5%), NF1 (n = 13, 4.5%), MYC (n = 9, 3.1%), GNAS (n = 8, 2.7%), PI3CA (n = 7, 2.4%), MET (n = 6, 2.08%), ATM in 6 (1.6%). Other genomic alterations of low frequency, but clinically relevant: AR (n = 4, 1.39%), TERT (n = 4, 1.39%), ERBB2 (n = 4, 1.39%), SMAD4 (n = 3, 1.04%), CDK4 (n = 2, 0.69%), NRAS (n = 2, 0.69%), FGFR1 (n = 2, 0.69%), FGFR2 (n = 2, 0.69%), PTEN (n = 2, 0.69%), RB1 (n = 2, 0.69%), and CDK6, CDKN2A, BRCA1, BRCA2, JAK2, IDH2, MAPK, NTRK1, CDH1, ARID1A, and PDGFRA were all reported once. Conclusions: Evaluation of ctDNA was feasible among individuals with AC. The frequency of genomic alterations in ctDNA testing is similar to those previously reported in tissue NGS. Liquid biopsies are non-invasive methods that can provide personalized options for targeted therapies in patients with AC.

Abstract B176: Sequential immunotherapy and association with clinical outcomes in advanced-stage cancer patients

Background: There are now six approved immune checkpoint inhibitors for several different malignancies including melanoma, head and neck cancer, lung cancer, and renal cell carcinoma. Given the increased number of available immunotherapeutic agents, more patients are presenting in clinic as candidates for sequential immunotherapy. However, the efficacy of sequential immunotherapy in a trial setting is unknown. We investigated the association between prior treatment with immune checkpoint inhibitors and clinical outcomes in patients treated with subsequent immunotherapy in a phase 1 clinical trial. Methods: We conducted a retrospective review of 90 advanced stage cancer patients treated on immunotherapy-based phase 1 clinical trials at Winship Cancer Institute between 2009 and 2017. We included 49 patients with an immune checkpoint-indicated histology (melanoma, lung cancer, head and neck cancer, and bladder cancer). Patients were then analyzed based on whether they had received at least one immune checkpoint inhibitor prior to enrollment. Overall survival (OS) and progression-free survival (PFS) were calculated in months from immunotherapy initiation on trial to date of death and clinical or radiographic progression, respectively. Clinical benefit (CB) was defined as a best response of complete response (CR), partial response (PR), or stable disease (SD). Univariate analysis (UVA) and multivariate analysis (MVA) were carried out using Cox proportional hazard or logistic regression model. Covariates included age, presence of liver metastases, number of prior lines of systemic therapy, histology, and Royal Marsden Hospital (RMH) risk group. Results: The median age was 67 years and most patients (78%) were men. The most common histologies were melanoma (61%) and lung/head and neck cancers (37%). The majority (81%) of patients were RMH good risk. More than half of patients (n=27, 55%) had received at least one immune checkpoint inhibitor prior to trial enrollment: ten received anti-PD-1, two received anti-CTLA-4, five received anti-PD-1/CTLA-4 combination therapy, and ten received multiple immune checkpoint inhibitors. In MVA, patients who had not received a prior immune checkpoint inhibitor had significantly longer OS (HR: 0.22, CI: 0.07-0.70, p=0.010). These patients also trended towards longer PFS (HR: 0.86, CI: 0.39-1.87, p=0.699) and higher chance of CB (HR: 2.52, CI: 0.49-12.97, p=0.268). Immunotherapy-naïve patients had substantially longer OS (24.3 vs 10.9 months) and PFS (5.1 vs. 2.8 months) than patients who had prior immunotherapy per Kaplan-Meier estimation. Conclusion: Optimal treatment options for oncology patients who progress on immune checkpoint inhibitors are lacking. In this study, patients who received at least one prior immune checkpoint inhibitor had worse clinical outcomes on immunotherapy-based phase 1 clinical trials than immune checkpoint-naïve patients. This suggests that further development of immunotherapy combination therapies is needed to improve clinical outcomes of these patients. The results from this study should be validated in a larger, prospective study.

Citation Format: Mehmet Bilen, Dylan Martini, Yuan Liu, Colleen Lewis, Hannah Collins, Julie Shabto, Mehmet Akce, Haydn Kissick, Bradley Carthon, Walid Shaib, Olatunji Alese, Rathi Pillai, Conor Steuer, Christina Wu, David Lawson, Ragini Kudchadkar, Bassel El-Rayes, Viraj Master, Suresh Ramalingam, Taofeek Owonikoko, R. Donald Harvey. Sequential immunotherapy and association with clinical outcomes in advanced-stage cancer patients [abstract]. In: Proceedings of the Fourth CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference: Translating Science into Survival; Sept 30-Oct 3, 2018; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2019;7(2 Suppl):Abstract nr B176.

Impact of genomic alterations (GAs) on outcomes and their distribution by age groups in metastatic colorectal cancer (mCRC) patients (pts)

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Background: Although clinical outcomes has substantially improved over the last decade, long term survival in mCRC remains rare. Molecular profiling (MP) of CRC is routinely conducted to identify potential therapeutic targets. The aim of this project is to evaluate the impact of uncommon GAs on outcomes and characterize their distribution by age. Methods: Pts were eligible if they had mCRC (synchronous or metachronous) and underwent MP between 01/2013 and 05/2018. GAs were obtained from Foundation Medicine reports. Clinical data were collected by trained personnel by detailed chart review. Multivariable survival analyses (MA) with Cox model were conducted for survival outcomes and Fisher’s exact test was used to assess the differences among age groups (< 45, 45-60, > 60). The study was reviewed by Institutional IRB ( IRB00097021 ). Results: 161 patients with mCRC had MP, and 159 of those patients had survival data. The most commonly detected GAs were APC (133/161, 82.6%) TP53 (128/161, 79.5%). In univariate analyses mutations in BRCA 1/2, RB1, SOX9, CDK8, FLT3, and IRS2 amplification were associated with worse survival outcomes. In MA, including initial stage of disease, GAs in BRCA1/2, RB1, FLT3, SOX9, and IRS2 remained statistically significant (Table). When we performed MA by age groups, mutations SOX9 in age group < 45 and BRCA1/2 in age group 45-60 were significant predictors of worse outcomes. We also compared the frequency of mutations among age groups and FAM123B was significantly more common in age group 45-60 (P = 0.038). Conclusions: Our data suggests that GAs in BRCA1/2, RB1, FLT3, SOX9, and IRS2 may predict worse outcomes in mCRC. Therapeutic approaches targeting these pathways should be investigated. Differences in distribution and prognostic significance of mutations were observed based on age. [Table: see text]

Clinical outcomes of hepatocellular carcinoma variants compared to hepatocellular carcinoma

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Background: There is no consensus regarding treatment for HCC variants. Clinical outcomes of HCC variants differ from pure HCC. The aim of this study is to compare clinicopathological characteristics, treatment, and outcomes of HCC variants with pure HCC. Methods: Patients with HCC and variants with 8170/3-8175/3 and 8180/3 ICD-O-3 codes were identified from National Cancer Database between 2004 and 2013. Univariate and multivariate survival analyses were conducted to analyze the association between histology and overall survival (OS). Results: 80,280 patients were identified; pure HCC 78,461 (97.7%), fibrolamellar (FLHCC) 310 (0.4%), scirrhous 161 (0.2%), spindle cell 72 (0.1%), clear cell 487 (0.6%), pleomorphic 23 (0.0%), and combined HCC and cholangiocarcinoma (mixed HCC) 766 (1.0%). 76.7% were male and 72% Caucasian. The mean age was similar in all except FLHCC (37.9 vs. 60.9-64.1 years, p < 0.001). Liver transplant was performed in 10.1% of pure HCC, 14.5% of mixed HCC, 16.2% of scirrhous, 6.9% of spindle cell, 8.8% of clear cell, 8.7% of pleomorphic, and 3.2% of FLHCC (p < 0.001). Pure HCC (10.57%) underwent surgical resection less often than variants; FLHCC (54.8%), clear cell (34.5%), mixed HCC (29.8%), spindle cell (33.3%), pleomorphic (34.8%), and scirrhous (9.9%) (p < 0.001). Ablation was performed in 9.8% of pure HCC, and in up to 8.7% of HCC variants. More than a third of all patients received chemotherapy; pure HCC (42.3%), mixed HCC (38.5%), scirrhous (31.1%), spindle cell (36.1%), clear cell (35.5%), pleomorphic (34.8%), and FLHCC (41.3%). FLHCC had the best 5-year OS (38.7%), spindle cell and pleomorphic had the worst (9.6% and 13.0%). In univariate and multivariate analyses, fibrolamellar histology, female sex, diagnosis between 2009 and 2013, treatment at academic center, well/moderately differentiated histology, early stage, and chemotherapy was associated with better OS compared to pure HCC, male sex, diagnosis between 2004 and 2008, treatment at community cancer program, poorly differentiated, late stage, and no chemotherapy (p < 0.001). Conclusions: HCC variants underwent surgical resection more often than HCC. FLHCC had the best 5-year OS. Liver transplant is commonly performed in HCC variants.

High-Grade Gastrointestinal Neuroendocrine Carcinoma Management and Outcomes: A National Cancer Database Study

BACKGROUND

High-grade neuroendocrine carcinomas are rare in the gastrointestinal tract. However, treatment patterns and outcomes have not been well described.

SUBJECTS, MATERIALS, AND METHODS

The National Cancer Database was analyzed. The primary objective was to describe the clinical outcomes and identify prognostic factors. Univariate and multivariate analyses were done to identify factors associated with patient outcome.

RESULTS

A total of 1,861 patients were identified between 2004 and 2013. The mean age was 63 years (standard deviation ±13). The majority of the patients (78.1%) were non-Hispanic whites. The most common primary sites were pancreas (pancreatic neuroendocrine tumor [PNET] = 19.4%), large intestine (18.1%), esophagus (17.8%), and rectum (15.5%). Stage at presentation was I (6.6%), II (10.5%), III (18%) and IV (64.6%). Only 1.6% of the patients had brain metastases. Surgical resection was the primary therapy in 27.9%, and their median overall survival (OS) was 13.3 months. Patients treated with palliative chemotherapy had a median OS of 11.2 months, compared with 1.7 months for untreated patients. The median OS for high-grade PNET was 6 months, compared with 9.9 months for other high-grade gastrointestinal neuroendocrine carcinomas (HG GI NEC). On univariable analysis, age < 65 years (hazard ratio [HR] 0.72; 0.66-0.8; p < .001) and treatment at an academic center (HR 0.88; 0.79-0.99; p < .034) were associated with improved survival. Multivariable analysis confirmed prognostic advantage of treatment at an academic center.

CONCLUSION

This is the largest series of HG GI NEC. Most patients present with metastatic disease, and overall survival remains poor. Treatment at an academic center, younger age, and use of chemotherapy were associated with improved survival. Multiagent chemotherapy was found to be associated with superior survival compared with single-agent chemotherapy, which was superior to no chemotherapy. Temporal sequences of chemotherapy, surgery, and radiation administration were not found to be associated with survival differences on multivariable analysis.

IMPLICATIONS FOR PRACTICE

Management of patients with high-grade gastrointestinal neuroendocrine carcinomas (HG GI NEC) is based on experience with small-cell lung cancer. In this retrospective review, most patients had advanced disease and pancreatic primary had worse outcomes. Treatment at an academic center, younger age, and use of chemotherapy are associated with improved survival. Patients with early-stage disease treated with resection alone had inferior outcomes compared with patients who received neoadjuvant or adjuvant therapy, suggesting that micrometastases contribute to poor surgical outcomes. The relatively high proportion of positive surgical margin favors downstaging with neoadjuvant therapy to improve resection and lower the risk of systemic recurrence.

Role of adjuvant therapy in resected stage IA subcentimeter (T1a/T1b) pancreatic cancer

BACKGROUND

The standard of care for patients with resected stage I to stage III pancreatic ductal adenocarcinoma (PDAC) is adjuvant gemcitabine-based chemotherapy. The role of adjuvant treatment in patients with subcentimeter, stage IA PDAC is unknown. The current study evaluated the effect of adjuvant treatment on survival outcomes among patients with American Joint Committee on Cancer/International Union Against Cancer stage IA (T1N0) resected PDAC using the National Cancer Data Base (NCDB).

METHODS

A retrospective review of the NCDB was conducted for patients diagnosed with T1 (tumor limited to the pancreas and measuring ≤2 cm in greatest dimension), lymph node-negative (N0), resected PDAC between 2004 and 2013. Patient demographics, histology, adjuvant treatment, and survival trends were examined. Kaplan-Meier analysis and log-rank tests were performed to determine the unadjusted association between overall survival (OS), tumor size, and treatment.

RESULTS

A total of 876 patients met the inclusion criteria. The patients had a mean age of 66.2 years (range, 32-90 years); approximately 83.3% were white (730 patients) and 53.1% were female (465 patients). Approximately 45.9% of the patients had moderately differentiated tumor histology (402 patients); 70.0% (613 patients) had tumors measuring 1 to 2 cm (T1c) and 30.0% (263 patients) had tumors measuring <1 cm (T1a/T1b). Approximately 94.2% of patients had negative surgical margins (815 patients) and 46.9% (410 patients) received adjuvant therapy. The median OS was significantly different for patients who received adjuvant therapy compared with patients who did not (70.7 months vs 46.9 months; P = .0001). For patients with tumors measuring <1 cm, survival was not found to be significantly different between patients who received adjuvant treatment compared with those who did not (not reached vs 85.3 months; P = .54). In the multivariable analysis, none of the covariates (treatment group, Charlson-Deyo Score, age, insurance, and facility status) demonstrated significant differences for patients with tumors measuring <1 cm.

CONCLUSIONS

The current study is the first to demonstrate no survival benefit for adjuvant therapy in patients with resected subcentimeter PDAC.