Impact of adjuvant therapy in patients with a microscopically positive margin after resection for gastroesophageal cancer

164

Background: A microscopically positive (R1) resection margin following resection for gastroesophageal (GE) cancer has been documented to be a poor prognostic factor. The optimal strategy and impact of different modalities of adjuvant treatment for an R1 resection margin remain unclear. Methods: A retrospective analysis was performed for patients (pts) with GE cancer treated at the Princess Margaret Cancer Centre from 2006-2016. Electronic medical records of all pts with an R1 resection margin were reviewed. Kaplan-Meier and Cox proportional hazards methods were used to analyze recurrence free survival (RFS) and overall survival (OS) with stage and neoadjuvant treatment as covariates in the multivariate analysis. Results: We identified 78 GE cancer pts with an R1 resection. 11% had neoadjuvant chemotherapy, 14% chemoradiation (CRT), 75% surgery alone. 28% had involvement of the proximal margin, 13% distal, 56% radial, 3% had multiple positive margins. By the American Joint Committee on Cancer 7th edition classification, 88% had a pT3-4 tumour, 66% pN2-3 nodal involvement, 64% grade 3, 68% with lymphovascular invasion. 3% were pathological stage I, 21% stage II and 74% stage III. Adjuvant therapy was given in 46% of R1 pts (24% CRT, 18% chemotherapy alone, 3% radiation alone, 1% reoperation). Median RFS for all pts was 12.6 months (95% CI 10.3-17.2). Site of first recurrence was 71% distant, 16% locoregional, 13% mixed. Median OS was 29.3 months (95% CI 22.9-50) for all pts. The 5 year survival rate was 23% (95% CI 12%-43%). There was no significant difference in RFS (log-rank test p= 0.63, adjusted p= 0.14) or OS (log-rank test p= 0.68, adjusted p= 0.65) regardless of adjuvant therapy. Conclusions: Most pts with positive margins after resection for GE cancer had advanced pathologic stage and prognosis was poor. Our study did not find improved RFS or OS with adjuvant treatment and only one pt had reresection. The main failure pattern was distant recurrence, suggesting that pts being considered for adjuvant RT should be carefully selected. Further studies are required to determine factors to select pts with good prognosis despite a positive margin, or those who may benefit from adjuvant treatment.

An updated retrospective review of the safety and efficacy of sorafenib for recurrent hepatocellular carcinoma post-liver transplantation

313

Background: Orthotopic liver transplantation (OLT) is a potentially curative treatment for hepatocellular carcinoma (HCC). Despite an estimated recurrence rate between 15%-20%, there is currently no proven systemic therapy for the treatment of HCC relapse post OLT. Sorafenib has been a standard therapy for advanced HCC however data is lacking for the safety and efficacy of sorafenib in the setting of concurrent immunosuppressive agents. Methods: A retrospective review was performed of patients who received sorafenib for HCC relapse after OLT. Data on patient characteristics, treatment toxicity and efficacy was collected. The primary objectives were to evaluate toxicity and safety of sorafenib when used in combination with immunosuppressive therapies such as calcineurin and mTOR inhibitors. Secondary objectives were objective response rate, progression free survival (PFS), and time on therapy. Results: 35 patients over the last 11 years received sorafenib for HCC recurrence following OLT. 54.3% of patients received concurrent immunosuppression with tacrolimus. Toxicity from sorafenib was as expected, with no cases of acute or chronic organ rejection whilst on treatment. The median maximum tolerated dose was 400 mg a day with 40% of patients requiring dose reductions. The incidence of any adverse events (AEs) was 88.6%, with 17.1% having Grade 3-4 toxicity. Incidence of Grade 3-4 liver dysfunction was higher than historical studies at 6%. The overall response rate was 2.8% with a median PFS of 2.8 months. Median time on sorafenib was 3.1 months. Conclusions: There is a paucity of evidence guiding treatment of HCC recurrence following OLT. This retrospective review is one of the largest in the literature and shows that sorafenib used concurrently with immunosuppressive therapy for organ transplant is safe, with no precipitation of acute or chronic rejection, although liver function should be monitored closely. The median PFS in our cohort was shorter than expected. The efficacy of other agents should be explored in this population.[Table: see text]

Surveillance and outcomes after curative resection for gastroesophageal adenocarcinoma (GEAC)

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Background: Although commonly performed, the benefit of routine surveillance testing (SvT) following curative resection of GEAC is undefined. We aimed to determine frequency of successful salvage therapy (SST) in patients (pts) with relapsed GEAC who were surveyed post curative therapy. Methods: Between 2011 and 2016, 210 consecutive pts with locally advanced GEAC underwent curative surgery and subsequent surveillance at Princess Margaret Cancer Center. SST was defined as any potentially curative therapy for recurrence which resulted in post-recurrence survival (PRS) two years without further relapse. Time-to-event outcomes were analyzed using Kaplan-Meier and Cox regression methods. Results: Median age was 64.1 years. Esophageal (14%), gastroesophageal junction (41%), and gastric adenocarcinomas (45%) were included. Pts received surgery alone (29%), surgery with perioperative chemotherapy (26%) or perioperative chemoradiation (45%) as primary curative therapy. At median follow-up of 33.6 months (m, range 6.0-122.4), 3- and 5-year overall survival (OS) rates were 68% (95% CI 61-75%) and 59% (95% CI 51-68%) respectively. SvT modalities included imaging (69%), endoscopy (19%), tumor markers (4%), and clinical visits only (9%). Recurrences occurred in 95 (45%) pts, 51% were surveillance-detected (SvDR), and 47% were non-SvDR. Types of recurrences included locoregional only (4%), distant (87%) or both (9%). Salvage therapy was attempted in 14 pts (7%) with SvDR and 1 with non-SvDR. In four pts with SvDR (1.9%) salvage therapy was successful with chemoradiation or surgery perioperative chemotherapy, six were unsuccessful, and 5 had immature follow-up. Compared with pts with non-SvDR, pts with SvDR had longer median OS (34.8 vs. 24.0m, p=0.03) and PRS (14.4 vs. 4.8m, p < 0.001), and similar time-to-relapse (15.6 vs. 12.0m, p = 0.67). Palliative chemotherapy was administered in 25 pts with SvDR and 18 pts with non-SvDR with similar median duration (3.5m vs. 3.3m, p=0.64). Conclusions: Following curative therapy, 96% of relapses were distant. SvT enabled SST in only 1.9% of pts, and did not extend duration of palliative chemotherapy. These data do not support the use of routine SvT in resected GEAC.

Survival outcomes for de novo versus relapsed stage IV gastric and gastroesophageal junction (GEJ) adenocarcinoma

148

Background: In gastric/GEJ cancer, 40% of patients (pts) are metastatic at diagnosis ( de novo stage IV) and up to 70% with locoregional disease recur (relapsed stage IV). We compared survival outcomes between de novo vs relapsed stage IV. Methods: A retrospective observational study of stage IV gastric/GEJ pts was conducted (2012-2015). Overall survival (OS) was from date of stage IV diagnosis. PFS1 defined the period from stage IV diagnosis to first progression. PFS2 was from first to second progression. For relapsed stage IV pts, disease-free interval (DFI) was the period from initial diagnosis to metastatic relapse. Cox proportional hazards models compared OS, PFS1 and PFS2 between de novo vs relapsed stage IV pts, stratified by DFI [ < 6, 6-12 and > 12 months (mo)] and controlled for baseline patient characteristics. Results: Of 198 pts, 62% were male and median age was 64 years (26-93), with 64% gastric and 36% GEJ adenocarcinomas. Primary therapy for locoregional pts included surgery (75%), perioperative chemotherapy (42%) and radiotherapy (42%). De novo and relapsed stage IV pts represented 68% and 32% of the cohort respectively. Median follow-up was 13 mo. Controlled for age, performance status and Charlson comorbidity index, there were no significant differences in OS (median OS 12.5 ( de novo) vs 12.2 mo (relapsed); HR 1.22, 95% CI 0.83-1.77, p = 0.31), PFS1 (6.8 vs 7.4 mo; HR 1.00, 95% CI 0.65-1.56, p = 0.98) or PFS2 (3.8 vs 3.0 mo; HR 1.03, 95% CI 0.44-2.41, p = 0.95). Median OS for relapsed stage IV patients were different by DFI groups (log-rank p = 0.02): 22.9 mo (for DFI > 12mo; n = 31), 11.2 mo (DFI 6-12; n = 19) and 7.5 mo (DFI < 6; n = 14). Additionally, OS was significantly better if the DFI was greater than 12 mo, compared with de novo stage IV (HR 0.50, 95% CI 0.28-0.88, p = 0.02). Conclusions: There was no observed difference in the natural history of de novo vs relapsed stage IV gastric/GEJ pts. DFI was strongly prognostic with median OS (from date of relapse) approaching 2 years for relapsed pts with DFI > 12 mo. In addition to implications for treatment strategy, tumor biology within subgroups should be examined to identify novel biomarkers and potential therapeutic targets.

Screening for cancer-associated dysphagia: The development of two rapid tools for use in observational studies and routine care

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Background: Dysphagia as a cancer symptom can be associated with significant morbidity. We developed dysphagia screener tools for use in observational studies (Phase 1) and routine symptom monitoring in clinical care (Phase 2). Methods: Various dysphagia or odynophagia screening questions, selected after an expert panel reviewed content, criterion, and construct validity, were compared to either FACT-E Swallowing Index Cut-Off Values (SICV) or to questions adapted from the Patient Reported Outcomes for Common Terminology Criteria for Adverse Events (PRO-CTCAE). Sensitivity, specificity and patient acceptability were assessed. Results: In developing a tool for observational studies (Phase 1; n = 178 esophageal cancer patients), the screening question, “How are you currently eating?” had the highest sensitivities and specificities against various SICV cut-offs, with the best optimal cut-off associated with the clinical outcome of weight loss (80% sensitivity, 75% specificity). When developing a rapid screening tool for routine symptom monitoring (Phase 2; 255 head and neck, gastro-esophageal, and patients undergoing thoracic radiation), a single question screener (“Do you experience any difficulty or pain upon swallowing?”) versus a PRO-CTCAE-like gold standard generated sensitivities between 86-94% and specificities between 93-100%. The screening question (+/- follow-up questions where indicated) had a median completion time of under 2 minutes, and > 90% of patients were happy to complete the survey on an electronic tablet, did not feel that survey completion made their clinic visit more difficult, and did not find the questions upsetting or distressful. Conclusions: Two screener tools (for prospective observational studies “How are you currently eating?”, and for routine clinical monitoring “Do you experience any difficulty or pain upon swallowing?”) can effectively screen dysphagia symptoms without increasing cancer outpatient clinic burden.

Management of metastatic gastric and esophageal cancer in older adults

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Background: Older adults are under-represented or excluded from pivotal trials of palliative chemotherapy for metastatic gastric and esophageal (GE) cancers. Little is known about how older patients are treated in the real world. The objective of this study was to examine the impact of age on treatment and survival. Methods: Patients aged ≥65 years were identified from a retrospective database of patients with metastatic GE cancer (Princess Margaret Cancer Centre; 2011-2016). The impact of age ≥75 years (old-old) versus (vs.) 65-74 years (young-old) on treatment and survival was assessed using multivariable logistic and Cox proportional hazard regression models, respectively, adjusted for known prognostic factors including sex, comorbidity, primary site, histology, grade, stage at initial diagnosis, metastatic sites, and chemotherapy use. Results: Of 183 patients, median age was 72 (range 65-92) years; 31% were old-old. Old-old patients were less likely to be treated with any chemotherapy (12.3% vs. 45.2% young-old; adjusted odds ratio = 0.12 (95% confidence interval (CI) 0.05-0.31)). With a median follow-up of 5.7 months, 135 (74%) had died during follow-up; median overall survival (OS) was 5.2 months (mo) for the old-old vs. 8.4 mo (young-old). There was no significant difference in survival between the two groups after adjustment for known prognostic factors (old-old vs. young-old: univariable hazard ratio (HR) 1.75 (95% CI 1.2-2.5); adjusted HR 1.1 (95% CI 0.7-1.7). Treatment with any chemotherapy was associated with an improvement in survival: adjusted HR 0.34 (95%CI 0.22-0.52). Conclusions: In this single-centre study of older adults with metastatic GE cancer, there was an overall low rate of treatment with chemotherapy; those ≥75 were rarely treated. After accounting for known prognostic factors, there was no observed difference in survival between patients ≥75 and those 65 to 74. Comprehensive geriatric assessment may improve treatment selection in the older population. [Table: see text]

Outcomes for advanced HER2-positive gastroesophageal cancer by anatomical location: Experience from the Princess Margaret Cancer Centre

131

Background: The landmark ToGA trial established trastuzumab (T) based therapy as the standard of care for advanced HER2+ gastric and gastroesophageal junction cancer. However, outcomes for T based therapy for HER2+ esophageal cancer have not been well characterized. Methods: We conducted a retrospective analysis of patients (pts) with HER2+ gastroesophageal cancer receiving T based therapy at our institution from 2011-2016. Distal esophagus ( < 35 cm) and Siewert type I/II tumours were defined as esophageal (E). Siewert type III and stomach tumours were defined as gastric (G). Trained abstractors collected pt demographics and treatment details. Overall survival (OS) and progression-free survival (PFS) were calculated from the date of first T treatment. Chi-square tests, t-tests and Cox proportional hazards models were applied where appropriate. Results: We identified 87 pts with advanced HER2+ disease. 62% (n = 54) had de novo metastatic (M1) disease. 57 patients were treated with T based therapy, with median age 57 years (IQR 48-67), 91% baseline performance status 0-1, 19% female, and 7% Asian. 63% (n = 36) had E and 37% (n = 21) had G primary tumours. 67% (n = 38) presented with M1 disease. 33% (n = 19) underwent surgery with curative intent and received T based therapy at recurrence. Baseline characteristics were balanced between the E and G groups. Survival data were available for 51 patients. The E and G groups did not have significant differences in PFS (median 9.5 vs. 9.1 months, HR 0.89 (95% CI 0.44-1.80), p = 0.74) or in OS (median 15.8 vs. 14.2 months, HR 0.88 (95% CI 0.42-1.82), p = 0.73). 63% (n = 36) were treated with subsequent systemic therapy after progression on T, with 23 receiving one line, 9 receiving two lines and 4 receiving three additional lines of treatment. The number subsequent therapies received was similar between E and G groups. Conclusions: Although patients with distal esophagus tumours were not included in the ToGA trial, our analysis suggests that patients with E and G tumours had similar outcomes. Our contemporary cohort had comparable survival outcomes relative to patients receiving T in the ToGA trial (median PFS = 6.7 months, median OS = 13.8 months).

Relationship between human epidermal growth factor receptor 2 (HER2) status and central nervous system metastases in gastroesophageal cancer

145

Background: Central nervous system (CNS) metastases (mets) in gastroesophageal (GE) cancers are rare. There have only been limited studies examining the role of HER2 status in CNS mets in GE cancers. Methods: A retrospective analysis was performed for patients (pts) treated for GE cancers at the Princess Margaret Cancer Centre from 2011-2016. Quantitative and qualitative data were collected for all pts with CNS mets. Kaplan-Meier method was used to calculate overall survival (OS) and CNS progression free survival (PFS) for CNS mets pts. Results: Of 34 GE cancer pts diagnosed with CNS mets, 11 were HER2+, 11 HER2- and 12 had unknown HER2 status. Median time from initial cancer diagnosis to CNS mets was 10.3 months (13.4 in HER2+, 5.8 in HER2-, 11.7 in HER2 unknown). Characteristics at CNS mets diagnosis included: median age 63; 85% male; 74% had extracranial systemic mets; performance status ECOG 0-1 (64%), 2 (12%), 3-4 (24%). Treatment for CNS mets is shown in Table 1. Median OS from diagnosis of CNS mets was 6.1 months (95%CI 3.2-16.4) for all pts, 17.1 (95%CI 9.9-NA) in HER2+, 1.8 (95%CI 0.6-NA) in HER2-, 6.0 (95%CI 1.9-NA) in HER2 unknown, p=0.01. Median OS from initial cancer diagnosis was 18.5 months (95%CI 13.6-33.7) for all pts, 28.9 (95%CI 21.32-NA) in HER2+, 10.8 (95%CI 6.37-NA) in HER2-, 18.6 (95%CI 10-NA) in HER2 unknown, p=0.015. The 1 year CNS PFS rate was 35% (95%CI 22.1 – 55.5%) for all pts, 53% (95%CI 29.9 – 94%) in HER2+, 18.2% (95%CI 5.3 – 63.7%) in HER2-, 33% (95%CI 15 – 74.2%) in HER2 unknown, p=0.053. Conclusions: HER2+ pts tended to develop CNS mets later than HER2-. HER2+ pts were more likely to receive CNS-directed interventions, with more HER2+ pts having surgery for CNS mets while more HER2- had supportive care. This analysis is the first to suggest that in pts with CNS mets, HER2+ pts had longer survival than HER2-, both from initial diagnosis and after developing CNS metastases.[Table: see text]

Tumor platinum concentrations and pathological responses following preoperative cisplatin-containing chemotherapy in gastric or gastroesophageal junction cancer patients

76

Background: Perioperative chemotherapy plus surgical resection is a standard of care for locally advanced gastric or gastroesophageal junction (GEJ) cancers. There is a wide range in tumor response following cisplatin-containing preoperative chemotherapy. We investigated the relationship between tumor platinum levels and pathological tumor responses in gastric or GEJ cancer patients following preoperative chemotherapy. Methods: Tumor and adjacent normal tissues were retrieved. Pathological responses were assessed per standard criteria. Tissue platinum concentrations were determined with high-performance liquid chromatography mass spectrometry. Platinum distribution in tissue components was evaluated with imaging mass cytometry. Tissue collagen content was evaluated using trichrome staining. Results: Ten patients were enrolled in this study. Nine patients received 3 cycles of preoperative chemotherapy and 1 received 2 cycles. The median cumulative cisplatin dose was 166.8 mg/m2 (range: 95.9–181.1 mg/m2). Surgery was performed at a median time of 49 days (range: 28–72 days) after the last cycle of chemotherapy. The mean platinum level in tumor tissue in patients with any response was 893 ± 460 pg, significantly higher than in those with no response [38.8 ± 8.8 pg (p = 0.007)]. The collagen content was significantly higher in patients with any response than in those with no response (37.4 ± 6.8% vs. 11.5 ± 8.6%, p < 0.05). Platinum preferentially bound to collagen. Conclusions: Platinum was detectable in surgical specimens up to 72 days after preoperative chemotherapy. Higher tumor platinum concentration correlated with improved pathological response. Collagen binding potentially explained the high interpatient variability in tumor platinum concentrations.

Baseline anemia in patients with biliary tract cancer (BTC) and its association with survival: A retrospective cohort study

426

Background: The prognostic significance of anemia in BTC is unknown, but is common and may be multifactorial; data regarding its causes are limited. This study interrogated a large institutional database to examine the effect of anemia on overall survival (OS) in BTC, and explore factors associated with anemia. Methods: This Princess Margaret Cancer Centre cohort study included patients with BTC with available baseline hemoglobin (Hb) (1987-2016). Anemia was defined as Hb < 132 mg/dL for men > 60 years, < 137mg/dL for men aged 20-59, and < 122mg/dL in women. Additional relevant covariates were included in multivariable Cox regression for OS, and linear regression for association with Hb. Results: Of 1398 patients included, 711 (51%) were anemic at baseline (mean Hb 112 mg/dL). Anemic versus non-anemic patients were older (median age 66 vs 64 yrs, p = 0.006), had worse ECOG PS (12% ECOG 2-3 vs 6%, p < .001), BMI < 20 (31% vs 27%, p = 0.006) and elevated neutrophil:lymphocyte ratio (NLR), (64% vs 47%, p < .001), but cancer staging was not significantly different. Anemia was associated with shorter OS on univariate (HR 1.35, p < .001) and multivariable (HR 1.39, p < .001) regression (Table). Factors associated with lower Hb included older age, male gender, worse ECOG PS, tumor site, thrombocytopenia, elevated NLR. Conclusions: Baseline anemia was associated with shorter survival following diagnosis of BTC, independent of tumor stage or ECOG PS. Clinicians should be aware of this prognostic marker; validation in prospective datasets is warranted. [Table: see text]

KEYNOTE-059 cohort 1: Pembrolizumab (Pembro) monotherapy in previously treated advanced gastric or gastroesophageal junction (G/GEJ) cancer in patients (Pts) with PD-L1+ tumors—Asian subgroup analysis

723

Background: The US FDA approved pembro for treating pts with 1) recurrent locally advanced or metastatic G/GEJ adenocarcinoma, whose disease has progressed on or after ≥2 prior therapies and whose tumors express PD-L1 (combined positive score [CPS] ≥1), and 2) unresectable or metastatic, microsatellite instability-high (MSI-H) solid tumors that have progressed after prior therapy and who have no fitting options. We report Asian subgroup analyses from cohort 1 of KEYNOTE-059 (NCT02335411), a global, phase 2 study in advanced G/GEJ cancer. Methods: Eligible pts had measurable recurrent or metastatic G/GEJ adenocarcinoma whose disease has progressed on ≥2 prior chemotherapy regimens. Pts received pembro 200 mg Q3W up to 2 y. PD-L1+ tumors had a CPS ≥1. Primary end points were ORR (RECIST 1.1, by central review) and safety. Results: Cohort 1 enrolled 259 pts; 57% had PD-L1+ tumors. MSI status was evaluable in 174 tumor samples; of these, 7 were MSI-H. At data cutoff (4/21/2017), median (range) follow-up was 6 mo (1-25). Overall ORR was 12% (95% CI, 8-17) and median (range) DOR was 14 mo (2-19+). PFS6-mo rate was 15% and OS6-mo rate was 46%. In pts with PD-L1+ tumors, ORR was 16% (95% CI, 11-23) and median (range) DOR was 14 mo (3+-19+). In pts with PD-L1+ tumors, PFS6-mo rate was 20% and OS6-mo rate was 50%. In pts with MSI-H tumors, ORR was 57% (95% CI, 18-90) and median (range) DOR was not reached (5-14+ mo). In cohort 1, 41 pts were Asian and 218 pts were non-Asian. PD-L1+ tumors occurred in 42% of Asian pts and 60% of non-Asian pts. ORR was 12% (95% CI, 2-36) in Asian pts with PD-L1+ tumors and 17% (95% CI, 11-24) in non-Asian pts with PD-L1+ tumors. One of 7 pts with MSI-H tumors was Asian; this pt had CR. Grade 3-5 treatment-related AEs occurred in 17% and 18% of Asian and non-Asian pts, similar to the overall cohort. Conclusions: Pembro showed durable clinical benefit in previously treated pts with advanced G/GEJ cancer, especially those with PD-L1+ or MSI-H tumors. Safety and efficacy were similar in Asian and non-Asian pts. These findings highlight pembro as a standard treatment option in Asian and non-Asian pts with advanced G/GEJ cancer. Clinical trial information: NCT02335411.

Comparison of bimodality versus trimodality therapy for esophageal or gastroesophageal junction (GEJ) cancer: Experience from the Princess Margaret Cancer Centre

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Background: There are no phase 3 trials comparing definitive chemoradiation (bimodality) versus. perioperative chemoradiation (trimodality) for locoregional esophageal/GEJ cancer. Methods: A retrospective analysis (2011-2015) compared bimodality and trimodality therapy in patients (pts) with locoregional esophageal/GEJ cancer treated with curative intent. Overall survival (OS) and disease-free survival (DFS) were calculated from the date of diagnosis. Uni- and multivariable Cox proportional hazards regression adjusted for patient and disease factors. Results: Of 108 patients, 82 (76%) were male. Mean ages were 69.5 ± 11.0 years (bimodality; N = 41) and 60.5 ± 11.1 years (trimodality; N = 67). For bimodality pts, 37% had adenocarcinoma and 63% had squamous cell carcinoma (SCC). For trimodality pts, 79% had adenocarcinoma and 21% had SCC (p < 0.0001). Bimodality pts received a higher radiation dose compared to trimodality pts (50.1 ± 6.7 vs. 45.2 ± 6.4 Gy). Median follow-up was 49.3 months. We found no significant OS difference between bimodality (27.0 months) and trimodality therapy (29.8 months) in the overall cohort (p = 0.57) (4 year OS rate: 42% vs. 38%). In the subgroup with adenocarcinoma histology, trimodality therapy significantly improved OS and DFS compared to bimodality (OS: 31.8 vs. 10.4 months, hazard ratio (HR) 0.34, 95% confidence interval (CI) 0.18-0.66, p = 0.001; DFS: 15.0 vs. 6.7 months; HR 0.39, 95%CI 0.21-0.73, p = 0.003). In the SCC subgroup, median OS and DFS were similar (OS: not reached vs. 29.2 months, p = 0.48; DFS: 27.0 vs. 24.0, p = 0.96). Using multivariable regression with AIC backward selection, the only retained prognostic factors were treatment modality (p = 0.06) and histology (p = 0.01). Conclusions: Our findings support preferential use of trimodality therapy for pts with adenocarcinoma histology given superior OS and DFS, whereas bimodality and trimodality therapy appeared comparable in pts with SCC histology. Pending confirmation in a larger series with longer follow-up, these findings suggest differential treatment algorithms for locoregional esophageal and GEJ cancer based on tumor histology.

Patterns of recurrence and outcomes after curative resection of locally advanced HER2-positive gastroesophageal cancer (HPGEC)

147

Background: Literature on recurrence and outcomes of HPGEC is scarce. The aim of this study was to determine pattern of recurrence and outcomes after curative intent surgery for locally advanced HPGEC. Methods: A retrospective database was used to identify consecutive patients with gastroesophageal adenocarcinomas undergoing curative intent resection between 2011 and 2016 at the Princess Margaret Cancer Centre. Clinico-demographic data were extracted from the electronic health record. Patterns of relapse are classified as nonvisceral (defined as recurrences in the bone, peritoneal or both), visceral (not nonvisceral, including the brain), or both. Time to relapse (TTR) and overall survival (OS) were calculated from date of histologic diagnosis. Results: Of 45 patients with HPGEC, 78% were male, and 91% were non-Asian. Median age was 64.4 years (interquartile range [IQR] 53, 70); 60% were gastroesophageal junction, 24% were gastric, and 16% were esophageal adenocarcinomas; 31% were poorly differentiated tumors while 68% had clinical or pathological node positive disease. Complete R0 resection occurred in 93%, and 84% had received perioperative therapy (31% with perioperative chemotherapy; 40% with pre-operative chemoradiation; 9% with post-operative chemoradiation). With a median follow-up time of 26.0 months. relapse rate of HPGEC at last follow-up was 78%. Among first relapses, 94% were distant, while 6% were local recurrences. Among distant relapses, visceral recurrences occurred in 85%, nonvisceral in 3%, and 12% patients had both visceral and nonvisceral recurrences. None had peritoneal only recurrence. Median TTR was 12.2 months (IQR 8.8, 23.5), while median post-recurrence survival was 9.7 months (IQR 4.7, 16.3). Of the entire cohort, 2-year OS was 53% and 3-year OS was 26%. Conclusions: More than three-quarters of patients with HPGEC experienced recurrence after curative intent multimodality therapy. Our results suggest that HPGEC rarely relapse with peritoneal only disease or local recurrence, thereby calling into question the utility for aggressive surveillance, pending verification from larger cohorts.

Comparison of chemoradiotherapy (CRT) using carboplatin/paclitaxel (CP) versus cisplatin/5-FU (CF) for esophageal or gastroesophageal junctional (GEJ) cancer

4053

Background: For resectable esophageal or GEJ cancer, trimodality therapy improves survival compared to surgery alone and represents the current standard of care. The optimal CRT regimen for neoadjuvant or definitive treatment of locoregional esophageal or GEJ cancer remains uncertain. Methods: A retrospective comparison of CF and CP for locoregional esophageal or GEJ cancer (2011-2015) was performed. Overall survival (OS) and disease-free survival (DFS) were assessed using multivariable Cox proportional hazards regression, controlling for age, performance status and Charlson comorbidity index. Results: 101 patients (pts) were identified (61 CF, 40 CP). 75% were male. Median age was 62 years (range 30-84). Primary sites were esophageal (52%, with 65% squamous histology) and GEJ (48%). Surgery was undertaken in 34 (56%) CF and 27 (68%) CP pts. Median follow-up was 43 months. Overall, there was a non-significant trend for improved OS with CF compared to CP (HR 0.61, 95% CI 0.33-1.14, p = 0.12). In the subgroup having surgery (N = 61), we found no significant difference in OS (HR 0.99, 95% CI 0.39-2.55, p = 0.99). In the subgroup without surgery (N = 40), CF was significantly superior to CP (HR 0.21, 95% CI 0.08-0.53, p < 0.001). Comparing only pts in this subgroup who received equitable radiation doses (N = 33), CF was still significantly superior to CP (HR 0.09, 95% CI 0.03-0.32, p < 0.001). OS was similar by histology (adenocarcinoma/squamous) in all-comers (p = 0.54), and in CF (p = 0.90) and CP subgroups (p = 0.63). DFS results corresponded with OS. There was a non-significant numerical difference in pCR rates between CF (31%) and CP (18%) (p = 0.35), which were lower than previously reported. Conclusions: Survival is similar for CF and CP CRT regimens in pts undergoing trimodality therapy, but for those who do not proceed to surgery, it appears that CF is more effective than CP. Clinicians may prefer CP for surgical candidates given its favourable toxicity profile. However, when treating with definitive CRT, CF may be preferable to CP as a standard regimen.

Outcomes for patients ≥75 years with localized gastroesophageal cancer: Experience from the Princess Margaret Cancer Centre

10037

Background: The optimal treatment and outcome for elderly patients (pts) with localized gastroesophageal (GE) cancer remains unclear as they are underrepresented in clinical trials. We aimed to assess survival in pts ≥75 years according to treatment received. Methods: A retrospective analysis was performed for all pts aged ≥75 years with GE cancer treated in 2012-2014. Frailty was measured using the Charlson comorbidity index (CCI) and ECOG performance status (PS). Overall survival (OS) and disease-free survival (DFS) were assessed via uni- and multivariable Cox proportional hazards regression, adjusting for demographics. Logistic regression analyses were used to examine factors impacting treatment choices. Results: Of 105 pts, median age was 81 years (range: 75-99), primary sites were esophageal (55%, with 43% squamous histology) and gastric (45%). Baseline characteristics included: PS: 0 (31%), 1 (42%), 2 (16%), 3 (10%), 4 (1%); and CCI: 0 (34%), 1 (25%), 2 (19%), ≥3 (22%). Treatment received included radiotherapy alone (RT) (31%); surgery alone (29%); surgery plus adjuvant chemotherapy (chemo) and/or RT (14%); chemoradiation alone (7%) and supportive care (18%). In univariable analyses; age < 85 (p = 0.003), PS < 2 (p = 0.03) and surgery (p < 0.001) were associated with improved OS. Chemo and RT, either alone or in combination, did not significantly improve OS. In multivariable analyses; surgery (HR 0.38, 95% CI 0.21-0.70, p = 0.002) was the only independent predictor for improved OS. Patients with good PS (p = 0.01), gastric disease site (p = 0.01) and adenocarcinoma histology (p = 0.02) were more likely to undergo surgery. Conclusions: At our institution, relatively few pts ≥75 years received multimodality therapy for localized GE cancers. Those pts ≥75 years who underwent surgery had excellent outcomes, but they were well-selected. Comprehensive assessment should be considered for pts ≥75 years with localized GE cancer to ensure optimal treatment selection, particularly given the potential benefit of surgery.

KEYNOTE-059 cohort 1: Efficacy and safety of pembrolizumab (pembro) monotherapy in patients with previously treated advanced gastric cancer

4003

Background: Pembro has shown promising antitumor activity and manageable safety in a phase 1 study of pts with previously treated advanced gastric cancer. We conducted a global, multicohort, phase 2 study of pembro in pts with advanced gastric or gastroesophageal junction (G/GEJ) cancer (KEYNOTE-059;NCT02335411). Methods: Cohort 1 enrolled 259 pts, aged ≥18 y with measurable recurrent or metastatic G/GEJ adenocarcinoma who had progressed on ≥2 prior chemotherapy regimens and had ECOG PS 0-1. Pts received pembro 200 mg Q3W up to 2 y or up to disease progression, investigator/pt decision to withdrawal, or unacceptable toxicity. PD-L1+pts had expression in ≥1% tumor or stromal cells using IHC (22C3 antibody). Primary end points: ORR (RECIST 1.1, by central review), safety, and tolerability. Results: Of 259 pts in cohort 1, 76.4% were men; median age was 62.0 y. 51.7% and 48.3% received pembro as 3rd-line (3L) and 4L+ therapy, respectively. 57.1% had PD-L1+ tumors. At data cutoff (Oct 19, 2016), median duration of follow-up was 5.4 mo (range, 0.5 to 18.7). Overall ORR (CR + PR) was 11.2% (95% CI, 7.6-15.7); 1.9% of pts (95% CI, 0.6-4.4) had CR, 9.3% had PR (95% CI, 6.0-13.5), 17% (95% CI, 12.6-22.1) had SD, and 55.6% (95% CI, 49.3-61.7) had PD. Median DOR was 8.1 mo (range, 1.4+ to 15.1+). ORR was 14.9% (95% CI, 9.4-22.1) in 3L pts and 7.2% (95% CI, 3.3-13.2) in 4L+. In PD-L1+ pts, ORR was 15.5% (95% CI, 10.1-22.4) with 2.0% (95% CI, 0.4-5.8) CR and 13.5% (95% CI, 8.5-20.1) PR; in PD-L1– pts, ORR was 5.5% (95% CI, 2.0-11.6), with 1.8% (95% CI, 0.2-6.5) CR and 3.7% (95% CI, 1.0-9.1) PR. In 3L pts with PD-L1+ tumors, ORR was 21.3% (95% CI, 12.7-32.3), with 4.0% (95% CI, 0.8-11.2) CR; in 3L pts with PD-L1– tumors, ORR was 6.9% (95% CI, 1.9-16.7), with 3.4% (95% CI, 0.4-11.9) CR. Grade 3-5 treatment-related AEs (TRAEs) occurred in 43 pts (16.6%). TRAEs led to discontinuation in 2 pts (abnormal LFT, bile duct stenosis) and were fatal in 2 pts (acute kidney injury, pleural effusion). Conclusions: Pembro showed encouraging efficacy and manageable safety after ≥2 prior lines of therapy in pts with advanced G/GEJ cancer in this large phase 2 trial. Survival and additional biomarker data, including MSI status, will be presented. Clinical trial information: NCT02335411.

Sorafenib treatment in recurrent hepatocellular carcinoma post liver transplantation

e15613

Background: Liver transplantation (LT) is a potentially curative treatment for patients (pts) with selective hepatocellular carcinoma (HCC). HCC recurrence post LT is estimated to be 15-20%. Data on systemic therapy post-recurrence is scarce and limited case series suggest that sorafenib (SOR) may have benefit in this population. We reviewed a single center experience with SOR in recurrent HCC post LT Methods: A retrospective review was conducted on pts with recurrent HCC post LT at University Health Network (UHN) who were treated with SOR. Pt characteristics were collected including age, gender, comorbidities, background liver disease, type of LT, and time to recurrence after LT. Treatment information collected included: initial SOR dose (and adjustments), adverse events (AEs), duration of treatment and survival. Results: Between 2006 and 2016, 24 pts were identified. The average age was 60 years (range: 18-72), most pts were male (20/4), living/cadaveric transplant: 11/13. HCC etiology included hepatitis B (10), alcohol (4), NASH (3), hepatitis C (2), hemochromatosis (2), Budd-Chiari (2) and unknown (1). The average time to recurrence of HCC was 16.08 (range: 1.5-60) months post OLT. There was a bimodal time to recurrence with a median of 6 months. SOR starting doses were 200 mg BID in 18 pts, 300 mg BID in 1 and 400 mg BID in 4. 14 pts required dose adjustment due to AEs, mainly relating to fatigue and palmar-plantar syndrome. The median time on treatment was 2.5 (range: 0.25-37) months. The average time to progression on SOR and/or discontinuation due to AEs was 4.30 (+/- 7.2) months. Conclusions: SOR is reasonably tolerated in pts with recurrent HCC post LT, with expected AE profiles. In this small case series, the median time on SOR was short and estimated time to progression was shorter than that in non-transplant HCC population. Overall, SOR has limited activity in this population, but selected pts may derive extended benefit. Better understanding of responders and investigations of other therapies are needed for this population.

Outcomes for patients ≥75 years with localized gastroesophageal cancer: Experience from the Princess Margaret Cancer Centre

189

Background: The optimal treatment and outcome for elderly patients (pts) with localized gastroesophageal (GE) cancer remains unclear as they are underrepresented in clinical trials. We aimed to assess survival in pts ≥ 75 years according to treatment received. Methods: A retrospective analysis was performed for all pts aged ≥ 75 years with GE cancer treated in 2012 and 2013. Frailty was measured using the Charlson comorbidity index (CCI) and ECOG performance status (PS). Overall survival (OS) and disease-free survival (DFS) were assessed via uni- and multivariable Cox proportional hazards regression, adjusting for demographics. Logistic regression analyses were used to examine factors impacting treatment choices. Results: Of 70 pts, median age was 82 years (range: 75-98), primary sites were esophageal (40%, with 61% squamous histology), GE junction (24%) and gastric (36%). Baseline characteristics included: PS: 0 (40%), 1 (39%), 2 (14%), 3 (7%); and CCI: 0 (36%), 1 (20%), 2 (21%), ≥ 3 (23%). Treatment received included surgery (33%), radiotherapy (RT) (31%); surgery plus adjuvant chemotherapy (chemo) and/or RT (9%); chemoradiation alone (7%) and 20% had no active treatment. In univariable analysis; age < 85 (p = 0.007) and surgery (p = 0.022) were associated with improved OS. Chemo and RT, either alone or in combination, did not significantly improve OS. In multivariable analysis; age < 85 (HR 0.46, 95% CI: 0.23-0.94, p = 0.034), surgery (HR 0.32, 95% CI: 0.14-0.74, p = 0.008) and CCI < 2 (HR 0.52, 95% CI: 0.27-0.99, p = 0.048) were identified as independent predictors for improved OS. Age ≥ 85 was significantly associated with omission of surgery (OR 3.61, 95% CI: 1.13-14.01, p = 0.041) but in contrast, PS ≥ 2 (p = 0.475) and CCI ≥ 2 (p = 0.939) were not predictive. Conclusions: At our institution, very few pts ≥ 75 years received multimodality therapy for localized GE cancers. Surgery was the only treatment modality associated with a significant survival advantage, and additional chemo and/or RT did not further improve OS. The only predictor for having surgery was age. Consequently, future studies should consider comprehensive assessment for surgery so that eligible elderly pts can benefit.

Comparison of chemoradiotherapy (CRT) with carboplatin/paclitaxel (CP) versus cisplatin/5-FU (CF) for esophageal or junctional cancer: Experience from the Princess Margaret Cancer Centre

126

Background: The optimal CRT regimen for neoadjuvant or definitive treatment of locoregional esophageal or gastroesophageal junctional (GEJ) cancer is uncertain. There has been no direct comparison between concurrent Cisplatin/5-FU (CF) as per the CALGB 9781 trial (50.4 Gy) or Carboplatin/Paclitaxel (CP) as per the CROSS trial (41.4 Gy). Methods: A retrospective analysis comparing CF and CP was performed in all patients (pts) with locoregional esophageal or GEJ cancer treated in 2012-2014. Overall survival (OS) and disease-free survival (DFS) were assessed via uni- and multivariable Cox proportional hazards regression, adjusting for age, performance status and Charlson comorbidity index. Pathological complete response (pCR) rates were compared using Fisher’s exact test. Results: 64/86 (74%) pts were male. Median age was 64 years (range: 34-84). Primary sites were esophageal (56%, with 60% squamous histology) and GEJ (44%, with 11% squamous). 22 pts received CRT in 2012 (100% CF), 33 pts in 2013 (58% CF, 42% CP) and 31 pts in 2014 (16% CF, 84% CP). Surgery was undertaken in 19 (41%) CF and 27 (68%) CP pts. Median follow-up was 38 months. We found no significant OS difference between CF and CP overall (HR 0.82, 95% CI: 0.43-1.56, p = 0.55) or in the subgroup having surgery (n = 46; HR 2.01, 95% CI: 0.62-6.55, p = 0.25). However, in the subgroup without surgery (n = 40), CF (n = 27) was superior to CP (n = 13)(HR 0.11, 95% CI: 0.03-0.38, p < 0.001). OS was similar by histology (adenocarcinoma/squamous) in all-comers (p = 0.96), and in CF (p = 0.66) and CP subgroups (p = 0.66). DFS results were similar to OS. There was a non-significant numerical difference in pCR rates between CF (31%) and CP (18%) (p = 0.45). Conclusions: Survival is similar for CF and CP CRT regimens in patients undergoing trimodality therapy. pCR rates were comparable but lower than previously reported. In contrast, in the absence of surgical resection, CP given for CRT results in significantly inferior outcomes. Clinicians may prefer CP for surgical candidates given its toxicity profile. However, when treating with definitive CRT, CF may be preferable to CP as a standard regimen.

Sorafenib treatment in recurrent hepatocellular carcinoma post liver transplantation

479

Background: Liver transplantation (LT) is a potentially curative treatment for patients (pts) with selective hepatocellular carcinoma (HCC). HCC recurrence post LT is estimated to be 15-20%. Data on systemic therapy post-recurrence is scarce and limited case series suggest that sorafenib (SOR) may have benefit in this population. We reviewed a single center experience with SOR in recurrent HCC post LT. Methods: A retrospective review was conducted on patients with recurrent HCC post LT at University Health Network (UHN) who were treated with SOR. Pt characteristics were collected including age, gender, comorbidities, background liver disease, type of LT, and time to recurrence after LT. Treatment information collected included: initial SOR dose and subsequent adjustments, adverse events (AEs), duration of treatment and survival. Results: Between 2006 and 2016, 24 patients were identified. The average age was 60 years (range: 18-72), most patients were male (20/4), living/cadaveric transplant: 11/13. HCC etiology included hepatitis B (10), alcohol (4), NASH (3), hepatitis C (2), hemochromatosis (2), Budd-Chiari (2) and unknown (1). The average time to recurrence of HCC was 16.08 (range: 1.5-60) months post LT. There was a bimodal time to recurrence with a median of 6 months. SOR starting doses were 200 mg BID in 18 pts, 300 mg BID in 1 and 400 mg BID in 4. 14 pts required dose adjustment due to AEs, mainly relating to fatigue and palmar-plantar syndrome. The median time on treatment was 2.5 (range: 0.25-37) months, 4/24 patients were on treatment > 6 months. The average time to progression on SOR and/or discontinuation due to AEs was 4.30 (+/- 7.2) months. Conclusions: SOR is reasonably tolerated in patients with recurrent HCC post LT, with expected AE profiles. In this small case series, the median time on sorafenib was short and estimated time to progression was shorter than that in non-transplant HCC population. Overall, sorafenib has limited activity in this population, but selected patients may derive extended benefit. Better understanding of responders and investigations of other therapies are needed for this population.