Search

PURPOSE Anti–epidermal growth factor receptor (EGFR) antibodies are effective treatments for metastatic colorectal cancer. Improved understanding of acquired resistance mechanisms may facilitate circulating tumor DNA (ctDNA) monitoring, anti-EGFR rechallenge, and combinatorial strategies to delay resistance. METHODS Patients with treatment-refractory metastatic colorectal cancer (n = 169) enrolled on the CO.26 trial had pre–anti-EGFR tissue whole-exome sequencing (WES) compared with baseline and week 8 ctDNA assessments with the GuardantOMNI assay. Acquired alterations were compared between patients with prior anti-EGFR therapy (n = 66) and those without. Anti-EGFR therapy occurred a median of 111 days before ctDNA assessment. RESULTS ctDNA identified 12 genes with increased mutation frequency after anti-EGFR therapy, including EGFR ( P = .0007), KRAS ( P = .0017), LRP1B ( P = .0046), ZNF217 ( P = .0086), MAP2K1 ( P = .018), PIK3CG ( P = .018), BRAF ( P = .048), and NRAS ( P = .048). Acquired mutations appeared as multiple concurrent subclonal alterations, with most showing decay over time. Significant increases in copy-gain frequency were noted in 29 genes after anti-EGFR exposure, with notable alterations including EGFR ( P < .0001), SMO ( P < .0001), BRAF ( P < .0001), MET ( P = .0002), FLT3 ( P = .0002), NOTCH4 ( P = .0006), ERBB2 ( P = .004), and FGFR1 ( P = .006). Copy gains appeared stable without decay 8 weeks later. There were 13 gene fusions noted among 11 patients, all but one of which was associated with prior anti-EGFR therapy. Polyclonal resistance was common with acquisition of ≥ 10 resistance related alterations noted in 21% of patients with previous anti-EGFR therapy compared with 5% in those without ( P = .010). Although tumor mutation burden (TMB) did not differ pretreatment ( P = .63), anti-EGFR exposure increased TMB ( P = .028), whereas lack of anti-EGFR exposure resulted in declining TMB ( P = .014). CONCLUSION Paired tissue and ctDNA sequencing identified multiple novel mutations, copy gains, and fusions associated with anti-EGFR therapy that frequently co-occur as subclonal alterations in the same patient.

Contemporary treatment of stage II/III rectal cancer combines chemotherapy, chemoradiation, and surgery, though the sequence of surgery with neoadjuvant treatments and benefits of minimally-invasive surgery (MIS) is debated.To describe patterns of surgical approach for stage II/III rectal cancer in relation to neoadjuvant therapies.A retrospective cohort was created using the National Cancer Database. Primary outcome was rate of sphincter-sparing surgery after neoadjuvant therapy. Secondary outcomes were surgical approach (open, laparoscopic, or robotic), surgical quality (R0 resection and 12+ lymph nodes), and overall survival.A total of 38927 patients with clinical stage II or III rectal adenocarcinoma underwent surgical resection from 2010-2016. Clinical stage II patients had neoadjuvant chemoradiation less frequently compared to stage III (75.8%Sphincter preservation rates are similar across stage II and III rectal cancer, regardless of delivery of preoperative chemotherapy, chemoradiation, or both. At a national level, there is a shift to predominantly MIS approaches for rectal cancer, regardless of whether sphincter sparing procedure is performed.

Treatment with the mTOR inhibitor everolimus improves progression-free survival in pancreatic neuroendocrine tumors, but it is not known if the addition of a VEGF pathway inhibitor to an mTOR inhibitor enhances antitumor activity. We performed a randomized phase II study evaluating everolimus with or without bevacizumab in patients with advanced pancreatic neuroendocrine tumors. One hundred and fifty patients were randomized to receive everolimus 10 mg daily with or without bevacizumab 10 mg/kg IV every 2 weeks. Patients in both arms also received standard dose octreotide. The primary endpoint was progression-free survival, based on local investigator review. Treatment with the combination of everolimus and bevacizumab resulted in improved progression-free survival compared to everolimus (16.7 months compared to 14.0 months; one-sided stratified log-rank p=0.1028; HR 0.80 (95% CI 0.56–1.13), meeting the predefined primary endpoint. Confirmed tumor responses were observed in 31% (95% CI 20%, 41%) of patients receiving combination therapy, as compared to only 12% (95% CI 5%, 19%) of patients receiving treatment with everolimus (P=0.0053). Median overall survival duration was similar in the everolimus and combination arm (42.5 months and 42.1 months, respectively). Treatment-related toxicities were more common in the combination arm. In summary, treatment with everolimus and bevacizumab led to superior progression-free survival and higher response rates compared to everolimus in patients with advanced pancreatic neuroendocrine tumors. Although the higher rate of treatment related adverse events may limit the use of this combination, our results support the continued evaluation of VEGF pathway inhibitors in pancreatic neuroendocrine tumors.

Peptide receptor radioligand therapy (PRRT) was Food and Drug Administration approved in 2018 for the treatment of unresectable somatostatin receptor-positive gastroenteropancreatic neuroendocrine tumors (NETs) and provides an important option for patients with advanced disease. A known adverse effect of this treatment is hematologic toxicity, although usually transient. We present 3 patients with metastatic gastroenteropancreatic NETs treated with PRRT who were evaluated for severe persistent thrombocytopenia.Three patients who commenced therapy with PRRT were known to proceed to a bone marrow (BM) biopsy for persistent severe thrombocytopenia and were included in this study. These patients were identified retrospectively and evaluated for their tumor properties, including immunohistochemical markers, treatment modalities, and clinical outcomes.All 3 patients had metastatic NETs that progressed on prior lines of therapy and were treated with 1 to 4 doses of 177Lu-DOTATATE 7.4 GBq (200 mCi) before developing grade 3 (25,000 to 50,000/μL) refractory thrombocytopenia. All patients had concurrent bone metastases, and 2 of the 3 had baseline grade 1 thrombocytopenia. In all 3 cases, BM biopsy documented widespread tumor infiltration.Severe refractory thrombocytopenia after PRRT is rare and may result from numerous known causes, including radiation-induced myelotoxicity, myelodysplastic syndrome, and tumor BM infiltration. We present 3 cases of thrombocytopenia related to persistent or progressive BM metastasis. Although known bone metastasis is not a contraindication to PRRT, thrombocytopenia may be a manifestation of tumor progression and should be considered when making decisions about continuation of therapy.

CDK10 expression in CRC based on a meta-analysis of independent gene expression profiling studies [7].

Effect of CDK10 expression on transcript levels of CDKs. CDK2, CDK4, CDK5, CDK6 and CDK9 expression in (A) MIP101 and (B) RKO CDK10 WT and DN overexpressing cells. Results represents n = 3, means {plus minus} SD.

Legends of Figures S1-S6

This serves as a white paper by the North American Neuroendocrine Tumor Society (NANETS) on the practical considerations when providing palliative care to patients with neuroendocrine tumors in the context of routine disease management or hospice care. The authors involved in the development of this manuscript represent a multidisciplinary team of patient advocacy, palliative care, and hospice care practitioners, endocrinologist, and oncologists who performed a literature review and provided expert opinion on a series of questions often asked by our patients and patient caregivers affected by this disease. We hope this document serves as a starting point for oncologists, palliative care teams, hospice medical teams, insurers, drug manufacturers, caregivers, and patients to have a frank, well-informed discussion of what a patient needs to maximize quality of life during routine, disease-directed care as well as at the end-of-life.

Supplemental Tables and Figure Caption

Supplemental Figure 1

Purpose:Expanded RAS/BRAF mutations have not been assessed as predictive for single-agent cetuximab in metastatic colorectal cancer (mCRC), and low mutant allele frequency (MAF) mutations are of unclear significance. We aimed to establish cetuximab efficacy in optimally selected patients using highly sensitive beads, emulsion, amplification, and magnetics (BEAMing) analysis, capable of detecting alterations below standard clinical assays.Patients and Methods:CO.17 trial compared cetuximab versus best supportive care (BSC) in RAS/BRAF-unselected mCRC. We performed RAS/BRAF analysis on microdissected tissue of 242 patients in CO.17 trial using BEAMing for KRAS/NRAS (codons 12/13/59/61/117/146) and BRAF V600E. Patients without BEAMing but with previous Sanger sequencing–detected mutations were included.Results:KRAS, NRAS, and BRAF mutations were present in 53%, 4%, and 3% of tumors, respectively. Cetuximab improved overall survival [OS; HR, 0.51; 95% confidence interval (CI), 0.32–0.81; P = 0.004] and progression-free survival (PFS; HR, 0.25; 95% CI, 0.15–0.41; P < 0.0001) compared with BSC in RAS/BRAF wild-type patients. Cetuximab did not improve OS/PFS for KRAS-, NRAS-, or BRAF-mutated tumors, and tests of interaction confirmed expanded KRAS (P = 0.0002) and NRAS (P = 0.006) as predictive, while BRAF mutations were not (P = 0.089). BEAMing identified 14% more tumors as RAS mutant than Sanger sequencing, and cetuximab lacked activity in these patients. Mutations at MAF < 5% were noted in 6 of 242 patients (2%). One patient with a KRAS A59T mutation (MAF = 2%) responded to cetuximab. More NRAS than KRAS mutations were low MAF (OR, 20.50; 95% CI, 3.88—96.85; P = 0.0038).Conclusions:We establish single-agent cetuximab efficacy in optimally selected patients and show that subclonal RAS/BRAF alterations are uncommon and remain of indeterminate significance.

BACKGROUND: Patients with chronic kidney disease are commonly excluded from clinical trials. The impact of chronic kidney disease on outcomes in patients with locally advanced rectal cancer has not been previously studied. OBJECTIVE: This study aimed to investigate the impact of chronic kidney disease on outcomes in patients with locally advanced rectal cancer. DESIGN: This is a multi-institutional, retrospective cohort study. SETTINGS: This study was conducted at academic and community cancer centers participating in the Canadian Health Outcomes Research Database Consortium Rectal Cancer Database. PATIENTS: Consecutive patients with locally advanced rectal cancer undergoing neoadjuvant chemoradiation before curative-intent surgery from 2005 to 2013 were selected. MAIN OUTCOME MEASURES: Disease-free survival, overall survival, pathologic complete response, and neoadjuvant chemotherapy/radiotherapy completion rate were the primary outcomes measured. RESULTS: A total of 1254 patients were included. Median age was 62, and 29%/69% had clinical stage II and III disease. Median estimated creatinine clearance was 93 mL/min, with 11%

We investigated the impact of new systemic therapies approved in Canada for colorectal cancer on the frequency, intensity and duration of oncology clinic and infusion visits over five treatment phases from diagnosis (P1, P3) to treatment (P2, P4) of primary and metastatic disease, respectively, and during the last 6 months of life (P5). In total, 15,157 adult patients with newly diagnosed colorectal cancer and referred between 2000 and 2012 to any cancer clinic in British Columbia, Canada, were included. Frequency, intensity and duration of medical oncology clinic visits (CVs), oncology infusions (OIs) and oncology prescriptions (OPs) were measured by treatment phase. Mean, total and adjusted total duration for CVs increased for P1-5. CVs increased in P1-5, and in P1-4 when adjusted by treatment length. Adjusted and unadjusted OIs decreased in P1 coinciding with the introduction of an oral treatment option, but increased in P2-5. Mean OI duration increased in P1-5, while total and adjusted total decreased in P1 and increased in P2-5. OPs increased in P2-4, but were unchanged in P1 and P5. Multi-fold increases in resources and time required per patient were also observed, which have significant implications for demand projections in cancer care planning and delivery. In conclusion, patients required more visits in almost all treatment phases, visits on average took longer and patients were in treatment for longer periods of time.

Peptide receptor radionuclide therapy (PRRT) is used to treat patients with advanced malignant pheochromocytomas (PCCs) and paragangliomas (PGLs). Patients are at risk of a PRRT-induced catecholamine crisis, and standard guidelines regarding the prevention and management of infusion reactions are lacking. In this case series, the institutional experience of five sequential patients with metastatic PCCs and PGLs receiving PRRT on an outpatient basis is described, of which four had symptomatic tumors and three had a high burden of disease. All patients with symptomatic tumors were treated with preventive management prior to the initiation of PRRT, and no infusion reactions or catecholamine crises were documented. PRRT may be delivered safely on an outpatient basis for patients with metastatic PCCs and PGLs with the involvement of an interdisciplinary team.

PURPOSE Organ-sparing therapy for early-stage I/IIA rectal cancer is intended to avoid functional disturbances or a permanent ostomy associated with total mesorectal excision (TME). The objective of this phase II trial was to determine the outcomes and organ-sparing rate of patients with early-stage rectal cancer treated with neoadjuvant chemotherapy followed by transanal excision surgery (TES). METHODS This phase II trial included patients with clinical T1-T3abN0 low- or mid-rectal adenocarcinoma eligible for endoscopic resection who were treated with 3 months of chemotherapy (modified folinic acid–fluorouracil-oxaliplatin 6 or capecitabine-oxaliplatin). Those with evidence of response proceeded to transanal endoscopic surgery 2-6 weeks later. The primary end point was protocol-specified organ preservation rate, defined as the proportion of patients with tumor downstaging to ypT0/T1N0/X and who avoided radical surgery. RESULTS Of 58 patients enrolled, all commenced chemotherapy and 56 proceeded to surgery. A total of 33/58 patients had tumor downstaging to ypT0/1N0/X on the surgery specimen, resulting in an intention-to-treat protocol-specified organ preservation rate of 57% (90% CI, 45 to 68). Of 23 remaining patients recommended for TME surgery on the basis of protocol requirements, 13 declined and elected to proceed directly to observation resulting in 79% (90% CI, 69 to 88) achieving organ preservation. The remaining 10/23 patients proceeded to recommended TME of whom seven had no histopathologic residual disease. The 1-year and 2-year locoregional relapse-free survival was, respectively, 98% (95% CI, 86 to 100) and 90% (95% CI, 58 to 98), and there were no distant recurrences or deaths. Minimal change in quality of life and rectal function scores was observed. CONCLUSION Three months of induction chemotherapy may successfully downstage a significant proportion of patients with early-stage rectal cancer, allowing well-tolerated organ-preserving surgery.

Cardiac metastases are an infrequent site of metastasis in neuroendocrine tumors, and the treatment implications in the era of peptide receptor radionuclide therapy (PRRT) are unclear. Potential safety concerns exist regarding cardiac integrity and function in response to PRRT. We describe our institutional experience with 4 patients with well-differentiated, midgut neuroendocrine tumors with cardiac involvement detected on Ga-DOTATATE PET/CT scans who were treated with PRRT.

Purpose: Expanded RAS/BRAF mutations have not been assessed as predictive for single-agent cetuximab in metastatic colorectal cancer (mCRC), and low mutant allele frequency (MAF) mutations are of unclear significance. We aimed to establish cetuximab efficacy in optimally selected patients using highly sensitive beads, emulsion, amplification, and magnetics (BEAMing) analysis, capable of detecting alterations below standard clinical assays. Patients and Methods: CO.17 trial compared cetuximab versus best supportive care (BSC) in RAS/BRAF-unselected mCRC. We performed RAS/BRAF analysis on microdissected tissue of 242 patients in CO.17 trial using BEAMing for KRAS/NRAS (codons 12/13/59/61/117/146) and BRAF V600E. Patients without BEAMing but with previous Sanger sequencing–detected mutations were included. Results: KRAS, NRAS, and BRAF mutations were present in 53%, 4%, and 3% of tumors, respectively. Cetuximab improved overall survival [OS; HR, 0.51; 95% confidence interval (CI), 0.32–0.81; P = 0.004] and progression-free survival (PFS; HR, 0.25; 95% CI, 0.15–0.41; P < 0.0001) compared with BSC in RAS/BRAF wild-type patients. Cetuximab did not improve OS/PFS for KRAS-, NRAS-, or BRAF-mutated tumors, and tests of interaction confirmed expanded KRAS (P = 0.0002) and NRAS (P = 0.006) as predictive, while BRAF mutations were not (P = 0.089). BEAMing identified 14% more tumors as RAS mutant than Sanger sequencing, and cetuximab lacked activity in these patients. Mutations at MAF < 5% were noted in 6 of 242 patients (2%). One patient with a KRAS A59T mutation (MAF = 2%) responded to cetuximab. More NRAS than KRAS mutations were low MAF (OR, 20.50; 95% CI, 3.88—96.85; P = 0.0038). Conclusions: We establish single-agent cetuximab efficacy in optimally selected patients and show that subclonal RAS/BRAF alterations are uncommon and remain of indeterminate significance.

Background Early cancer detection could identify tumors at a time when outcomes are superior and treatment is less morbid. This prospective case-control sub-study (from NCT02889978 and NCT03085888) assessed the performance of targeted methylation analysis of circulating cell-free DNA (cfDNA) to detect and localize multiple cancer types across all stages at high specificity. Participants and methods The 6689 participants [2482 cancer (>50 cancer types), 4207 non-cancer] were divided into training and validation sets. Plasma cfDNA underwent bisulfite sequencing targeting a panel of >100 000 informative methylation regions. A classifier was developed and validated for cancer detection and tissue of origin (TOO) localization. Results Performance was consistent in training and validation sets. In validation, specificity was 99.3% [95% confidence interval (CI): 98.3% to 99.8%; 0.7% false-positive rate (FPR)]. Stage I–III sensitivity was 67.3% (CI: 60.7% to 73.3%) in a pre-specified set of 12 cancer types (anus, bladder, colon/rectum, esophagus, head and neck, liver/bile-duct, lung, lymphoma, ovary, pancreas, plasma cell neoplasm, stomach), which account for ∼63% of US cancer deaths annually, and was 43.9% (CI: 39.4% to 48.5%) in all cancer types. Detection increased with increasing stage: in the pre-specified cancer types sensitivity was 39% (CI: 27% to 52%) in stage I, 69% (CI: 56% to 80%) in stage II, 83% (CI: 75% to 90%) in stage III, and 92% (CI: 86% to 96%) in stage IV. In all cancer types sensitivity was 18% (CI: 13% to 25%) in stage I, 43% (CI: 35% to 51%) in stage II, 81% (CI: 73% to 87%) in stage III, and 93% (CI: 87% to 96%) in stage IV. TOO was predicted in 96% of samples with cancer-like signal; of those, the TOO localization was accurate in 93%. Conclusions cfDNA sequencing leveraging informative methylation patterns detected more than 50 cancer types across stages. Considering the potential value of early detection in deadly malignancies, further evaluation of this test is justified in prospective population-level studies.

Background Somatostatin analog functional imaging with gallium-68 (Ga-68) dotatate positron emission tomography/computed tomography (PET/CT) has demonstrated superiority in lesion detection in patients with neuroendocrine tumors (NETs). The clinical impact of this imaging modality on US surgical and medical oncology practices has not been established. Methods Consecutive patients with NET at our institution who received an initial Ga-68 dotatate PET/CT between July 2017 and September 2018 were included. Ga-68 dotatate PET/CT was compared with prior imaging. Results Among 101 eligible patients, 51 of 50 were female/male, site of origin was gastroenteropancreatic (75%), unknown primary (13%), lung (8%), thymus (2%), and other (2%). All NETs were histologically well/moderately differentiated. Ga-68 dotatate imaging findings altered management in 36 (35.6%) patients: documentation of progression led to the initiation of systemic therapy in 14 patients, obviated the need for biopsy in four patients, and altered surgical plans in 7 of 14 (50%) patients referred for surgery. In 11 patients, decisions regarding peptide receptor radionucleotide therapy and somatostatin analogs were altered. Conclusions In this series, Ga-68 dotatate PET/CT altered diagnosis and management in one-third of patients and changed operative plans in half of the patients who were referred for surgical evaluation. These results support the routine use of this imaging in the care of patients with early-stage and advanced NETs.

BACKGROUND: Appendiceal neuroendocrine tumors (A-NETs) are rare neoplasms of the GI tract. They are typically managed according to tumor size; however, the impact of surgical strategy on the short- and long-term outcomes is unknown. METHODS: All patients who underwent resection of A-NET at 8 institutions from 2000 to 2016 were analyzed retrospectively. Patient clinicopathologic features and outcomes were stratified according to resection type. RESULTS: Of 61 patients identified with A-NET, mean age of presentation was 44.7 ± 16.0 years and patients were predominantly Caucasian (77%) and female (56%). Mean tumor size was 1.2 ± 1.3 cm with a median of 0.8 cm. Thirty-one patients (51%) underwent appendectomy and 30 (49%) underwent colonic resection. The appendectomy group had more T1 tumors (87% vs 42%, p < 0.01) than the colon resection group. Of patients in the colon resection group, 27% had positive lymph nodes and 3% had M1 disease. R0 resections were achieved in 90% of appendectomy patients and 97% of colon resection patients. Complications occurred with a higher frequency in the colon resection group (30%) compared with those in the appendectomy group (6%, p = 0.02). The colon resection group also had a longer length of stay, higher average blood loss, and longer average OR time. Median RFS and OS were similar between groups. CONCLUSION: A-NET RFS and OS are equivalent regardless of surgical strategy. Formal colon resection is associated with increased length of stay, OR time, higher blood loss, and more complications. Further study is warranted to identify patients that are likely to benefit from more aggressive surgery.

Therapy-refractory disease is one of the main contributors of treatment failure in cancer. In colorectal cancer (CRC), SPARC can function as a sensitizer to conventional chemotherapy by enhancing apoptosis by interfering with the activity of Bcl-2. Here, we examine a novel mechanism by which SPARC further potentiates apoptosis via its modulation of the unfolded protein response (UPR). Using mass spectrometry to identify SPARC-associated proteins, GRP78 was identified as a protein partner for SPARC in CRC. In vitro studies conducted to assess the signaling events resulting from this interaction, included induction of ER stress with tunicamycin, 5-fluorouracil (5-FU), and irinotecan (CPT-11). We found that the interaction between GRP78 and SPARC increased during exposure to 5-FU, CPT-11, and tunicamycin, resulting in an attenuation of GRP78’s inhibition of apoptosis. In addition, we also show that SPARC can sensitize CRC cells to PERK/eIF2α and IRE1α/XBP-1 UPR signaling by interfering with ER stress following binding to GRP78, which leads to ER stress-associated cell death in CRC cells. In line with these findings, a lower expression of GRP78 relative to SPARC in CRC is associated with a lower IC50 for 5-FU in either sensitive or therapy-refractory CRC cells. Interestingly, this observation correlates with tissue microarray analysis of 143 human CRC, where low GRP78 to SPARC expression level was prognostic of higher survival rate (P = 0.01) in individuals with CRC. This study demonstrates that modulation of UPR signaling by SPARC promotes ER stress-associated death and potentiates apoptosis. This may be an effective strategy that can be combined with current treatment options to improve therapeutic efficacy in CRC.

Gastric carcinoids are rare neuroendocrine tumors of the gastrointestinal tract. They are typically managed according to their etiology. However, there is little known about the impact of surgical strategy on the long-term outcomes of these patients.All patients who underwent resection of gastric carcinoids at 8 institutions from 2000 to 2016 were analyzed retrospectively. Tumors were stratified according to subtype (I, II, III, IV) and resection type (local resection, LR or formal gastrectomy, FG). Clinicopathological parameters, recurrence-free (RFS) and overall survival (OS) were compared between groups.Of 79 patients identified with gastric carcinoids, 34 had type I lesions associated with atrophic gastritis, 4 had type II lesions associated with a gastrinoma, 37 had type III sporadic lesions, and 4 had type IV poorly-differentiated lesions. The mean age of presentation was 56 years in predominantly Caucasian (77%) and female (63%) patients. Mean tumor size was 2.4 cm and multifocal tumors were found in 24 (30%) of patients with the majority occurring in those with type I tumors. Lymph node positive tumors were seen in 15 (19%) patients and 7 (8%) had M1 disease; both most often in type IV followed by type III tumors. R0 resection was achieved in 56 (71%) patients while 15 (19%) had R1 resections and 6 (8%) R2 resections. Patients with type I and III tumors were equally likely to have a LR (50% and 43% respectively) compared to FG while those with type II and IV all had FG with one exception. Type IV tumors had the poorest RFS and OS while Type II tumors had the most favorable RFS and OS (p 0.04 and p 0.0004, respectively). While there was no difference in RFS in those patients undergoing FG versus LR, OS was worse in the FG group (p 0.017). This trend persisted when type II and type IV groups were excluded (p 0.045).Gastric carcinoid treatment should be tailored to tumor type, as biologic behavior rather than resection technique is the more important factor contributing to long-term outcomes.

ImportanceThis study quantifies the trends in trimodality therapy use and its association with pathologic stage and overall survival of patients with rectal cancer at the population level.ObjectiveTo describe changes between 2006 and 2016 in the sequence and use of chemotherapy/radiation therapy (C/RT), multiagent (MA) chemotherapy, and total neoadjuvant therapy (TNT) for patients with stage 2/3 rectal cancer and identify associations with pathologic stage and survival over time.Design, Setting, and ParticipantsThis retrospective cohort analysis included patient records from the National Cancer Database between 2006 and 2016. Of 110 372 patient records, 77 905 were excluded owing to not receiving trimodality therapy and other predefined exclusion criteria. The final analytic cohort comprised 32 467 patients records treated with trimodality therapy, with 24 297 considered in the survival analysis. Data analysis was performed between June 2020 and December 2021.ExposuresTrimodality therapy was defined as including all of the following: definitive surgery; radiation therapy (RT), alone or in combination with chemotherapy; and neoadjuvant/adjuvant single-agent (SA) or multiagent (MA) chemotherapy independent of RT.Main Outcomes and MeasuresUsing Cox multivariable survival analyses across demographics, surgery type, stage, year of diagnosis, and facility type, treatment groups were allocated as the following: group A: TNT (n = 8883 [27%]); group B: preoperative C/RT plus postoperative SA chemotherapy (n = 5967 [18%]); group C: preoperative C/RT plus postoperative MA chemotherapy (n = 12 926 [40%]); and group D: postoperative C/RT plus MA chemotherapy (n = 4689 [14%]).ResultsThe final analytic cohort comprised 32 467 patients (mean [SD] age at diagnosis, 57.6 [11.6] years; 12 549 [38.7%] women and 19 918 [61.3%] men). Comparing 2016 with 2006, treatment shifted to fewer patients receiving postoperative C/RT (group D) (28% vs 8%; P P P Conclusions and RelevanceIn this cohort study, the shift toward preoperative C/RT and lower pathologic stage was associated with improved overall survival in stage 2/3 rectal cancers.

When the COVID-19 pandemic began, formal frameworks to collect data about affected patients were lacking. The COVID-19 and Cancer Consortium (CCC19) was formed to collect granular data on patients with cancer and COVID-19 at scale and as rapidly as possible. CCC19 has grown from five initial institutions to 125 institutions with >400 collaborators. More than 5,000 cases with complete baseline data have been accrued. Future directions include increased electronic health record integration for direct data ingestion, expansion to additional domestic and international sites, more intentional patient involvement, and granular analyses of still-unanswered questions related to cancer subtypes and treatments.

Pancreatic neuroendocrine tumours (pnets) often present as advanced disease. The optimal sequence of therapy is unknown. Sequential patients with advanced pnets referred to BC Cancer between 2000 and 2013 who received 1 or more treatment modalities were reviewed, and treatment patterns, progression-free survival (pfs), and overall survival (os) were characterized. Systemic treatments included chemotherapy, small-molecule therapy, and peptide receptor radionuclide therapy. In 66 cases of advanced pnets, median patient age was 61.2 years (25%&ndash, 75% interquartile range: 50.8&ndash, 66.2 years), and men constituted 47% of the group. First-line therapies were surgery (36%), chemotherapy (33%), and somatostatin analogues (32%). Compared with first-line systemic therapy, surgery in the first line was associated with increased pfs and os (20.6 months vs. 6.3 months and 100.3 months vs. 30.5 months respectively, p < 0.05). In 42 patients (64%) who received more than 1 line of therapy, no difference in os or pfs between second-line therapies was observed. Our results confirm the primary role of surgery for advanced pnets. New systemic treatments will further increase options.

BACKGROUND: Expanded RAS/BRAF mutations have not been assessed as predictive for single-agent cetuximab in metastatic colorectal cancer (mCRC) and low mutant allele frequency (MAF) mutations are of unclear significance. We aimed to establish cetuximab efficacy in optimally selected patients using highly sensitive BEAMing, capable of detecting alterations below standard clinical assays. METHODS: CO.17 compared cetuximab versus best supportive care (BSC) in RAS/BRAF unselected mCRC. We performed RAS/BRAF analysis on micro-dissected tissue of 242 patients in CO.17 using BEAMing for KRAS/NRAS (codons 12/13/59/61/117/146) and BRAF V600E. Patients without BEAMing but with previous Sanger sequencing detected mutations were included. RESULTS: KRAS, NRAS, and BRAF mutations were present in 53%, 4%, and 3% of tumors, respectively. Cetuximab improved overall survival (OS) (HR 0.51, 95% CI 0.32–0.81, P=0.004) and progression free survival (PFS) (HR 0.25, 95% CI 0.15–0.41, P

OBJECTIVES There is limited randomized data to guide second-line chemotherapy selection in advanced pancreatic cancer (APC). We aimed to characterize predictors and outcomes of second-line chemotherapy in patients with APC. METHODS We identified all patients with APC [locally advanced (LAPC) or metastatic (MPC)] who received ≥1 cycle of first-line chemotherapy between January 2012 and December 2015 across 6 cancer centers in British Columbia, Canada. Baseline characteristics and survival outcomes were summarized. RESULTS Of 676 patients with APC (31% LAPC, 69% MPC) who received ≥1 cycle of chemotherapy, 164 (24%) received second-line chemotherapy. These patients were younger, with lower ECOG and higher CA19-9 at presentation, compared with patients who did not receive second-line chemotherapy. There were no differences in rates of second-line chemotherapy between LAPC and MPC (28% vs. 23%; P=0.18). Only first-line FOLFIRINOX was associated with second-line chemotherapy. Median overall survival (OS) from second-line chemotherapy was longer with second-line gemcitabine/nab-paclitaxel than fluoropyrimidine or gemcitabine (7.9 vs. 5.1 vs. 4.3 mo; P=0.008). On multivariable analysis, longer OS from second-line chemotherapy was associated with gemcitabine/nab-paclitaxel, lower ECOG, and LAPC. CONCLUSIONS In this population-based cohort, first-line FOLFIRINOX was the strongest predictor of second-line chemotherapy. Duration of therapy remains short and novel treatments are urgently needed.

An increasing number of studies are describing potential uses of circulating tumour DNA (ctDNA) in the care of patients with colorectal cancer. Owing to this rapidly developing area of research, the Colon and Rectal–Anal Task Forces of the United States National Cancer Institute convened a panel of multidisciplinary experts to summarize current data on the utility of ctDNA in the management of colorectal cancer and to provide guidance in promoting the efficient development and integration of this technology into clinical care. The panel focused on four key areas in which ctDNA has the potential to change clinical practice, including the detection of minimal residual disease, the management of patients with rectal cancer, monitoring responses to therapy, and tracking clonal dynamics in response to targeted therapies and other systemic treatments. The panel also provides general guidelines with relevance for ctDNA-related research efforts, irrespective of indication., The analysis of ctDNA obtained from low-volume blood samples has the potential to transform the management of patients with colorectal cancer. Nevertheless, research priorities and minimum standards for sample collection and analysis in this area are currently missing. In this Position Paper, the NCI Colon and Rectal–Anal Task Forces provide a set of recommendations designed to address these challenges and accelerate the implementation of ctDNA in the management of patients with colorectal cancer.

PURPOSE: Few studies have directly compared health care utilization, costs, and outcomes between patients treated in the US multipayer health system and Canada’s single-payer system. Using cancer registry and claims data, we assessed treatment types, costs, and survival for patients with metastatic colorectal cancer (mCRC) in Western Washington State (WW) and British Columbia (BC). MATERIALS AND METHODS: Patients age ≥ 18 years diagnosed with mCRC in 2010 and later were identified from the BC Cancer database and a regional database linking WW SEER to claims from Medicare and two large commercial insurers. Demographics, treatment characteristics, costs of systemic therapy, and survival data were obtained from these databases and compared between the two regions. RESULTS: A total of 1,592 patients from BC and 901 from WW were included in the study. Median age was similar (BC, 66 years; WW, 63 years), but patients in BC were more likely to be male (57.1% v 51.2%; P ≤ .01) and to have de novo metastatic disease (61.0% v 38.3%; P ≤ .01). The use of radiation therapy was similar between regions (BC, 31.2%; WW, 33.9%; P = .18), but primary tumor resection was more common in BC (74.1% v 66.3%; P ≤ .01) as was hepatic metastasectomy (12.4% v 2.3%; P ≤ .01). Similar percentages of patients received systemic therapy (BC, 68.8%; WW, 67.1%; P = .40), but costs were significantly higher for first-line systemic therapy in WW ($6,226 v $15,792 per patient per month; P ≤ .01). Median overall survival was similar (BC, 16.9 months; WW, 18 months). CONCLUSION: Cost of systemic therapy for mCRC was significantly higher for patients in WW than in BC, but this did not translate to a difference in overall survival.

Use of adjuvant chemotherapy (AC) following neoadjuvant chemoradiation (nCRT) is controversial in rectal cancer (RC). We assessed a multi-institutional database to determine if there was benefit from AC for pathologic stage II RC patients and whether the addition of oxaliplatin to fluoropyrimidine (OXAC) therapy impacted outcomes.We included patients who underwent nCRT and had pathologic stage II (ypT3/4 ypN0) tumors. Disease-free survival and overall survival were assessed. Multivariate Cox models adjusting for age, sex, Eastern Cooperative Oncology Group, high-risk features (pT4, poor differentiation,12 nodes removed, lymphovascular/perineural invasion, or obstruction/perforation), and clinical stage were constructed.Of 485 patients, 73.6% received AC, of which 25.5% received OXAC. Patients receiving AC were younger (median age 61 vs. 64; P=0.003) and had higher rates of total mesorectal excision (81.5% vs. 78.9%; P=0.049), but had similar high-risk features, performance status, clinical stage, margin status, preoperative carcinoembryonic antigen, and nCRT regimen. In univariate analysis, overall survival was improved with fluoropyrimidine AC compared with no AC or OXAC (P=0.049), but not disease-free survival (P=0.33). In multivariate analysis, any AC, fluoropyrimidine AC, or OXAC did not improve outcomes. After stratifying patients by the presence of high-risk features, elevated carcinoembryonic antigen, margin status, or preoperative clinical stage, we did not identify a group with improved outcomes following AC.In this multi-institutional cohort of yp stage II RC patients, we failed to identify a group that derives benefit from AC following nCRT. The addition of oxaliplatin did not appear to improve outcomes when compared with fluoropyrimidine alone.

Goblet cell carcinoids (GCCs) of the appendix are rare mucinous neoplasms, for which optimal therapy is poorly described. We examined prognostic clinical and treatment factors in a population-based cohort. Patients diagnosed with GCC from 1984 to 2014 were identified from the British Columbia Cancer Agency and the Vancouver Lower Mainland Pathology Archive. Of 88 cases with confirmed appendiceal GCCs, clinical data were available in 86 cases (annual population incidence: 0.66/1,000,000). Median age was 54 years (range 25–91) and 42 patients (49%) were male. Metastasis at presentation was the strongest predictor of overall survival (OS), with median OS not reached for stage I–III patients, and measuring 16.2 months [95% confidence interval (CI) 9.1–29] for stage IV patients. In 67 stage I–III patients, 51 (76%) underwent completion hemicolectomy and 9 (17%) received adjuvant 5-fluorouracil-based chemotherapy. No appendicitis at initial presentation and Tang B histology were the only prognostic factors, with inferior 5-year recurrence-free survival (53 vs. 83% with appendicitis, p = 0.02; 45% Tang B vs. 89% Tang A, p

710 Background: CAPOX and FOLFOX are used interchangeably in the adjuvant treatment of colon cancer despite the lack of comparative phase III trials.We aimed to compare toxicities, relative dose intensity (RDI), disease free (DFS) and overall survival (OS) of these regimens in the real world. Methods: We identified consecutively treated patients (pts) with stage III colon cancer at two centers who received either CAPOX or mFOLFOX6 when either option was accessible to pts. RDI was defined as total dose received divided by the total intended dose if all cycles had been delivered. Dose limiting toxicities (DLTs) were toxicities that resulted in a dose reduction of an agent. Survival was compared with the log-rank test and Cox models that adjusted for age, gender, ECOG, T-stage, and N-stage. Results: Of 394 pts, 61.7% received FOLFOX. Age, gender, ECOG, T-stage, N-stage, and time between surgery and start of therapy did not differ between groups. However, RDI and toxicity profiles differed between treatment groups (see Table). With a median follow up of 45 months, there was no difference in OS (HR 0.73, 95%CI 0.45-1.22; P= 0.24); however, CAPOX was associated with a more favorable DFS (HR 0.61, 95% CI 0.40-0.93; P= 0.022). In multivariate analysis, treatment with CAPOX showed trends towards improved OS (HR 0.61, 95% CI 0.34-1.07; P= 0.086). A significant association with improved DFS (HR 0.53, 95% CI 0.33-0.87; P= 0.012) persisted. Exploratory analysis comparing outcomes stratified by the presence of any DLT, neutropenia, thrombocytopenia, and neuropathy failed to show an association with either OS or DFS. (See table.) Conclusions: Our findings suggest that the use of adjuvant CAPOX is associated with an improved DFS despite greater toxicity and lower RDI. Patient selection, the higher starting dose of oxaliplatin in CAPOX, or the metronomic nature of capecitabine may be contributing to improved efficacy of CAPOX. [Table: see text]

Purpose Chemotherapy remains the primary treatment for metastatic gastric/GEJ cancer but optimal agents and schedule remain controversial. This study examined the safety and efficacy of first-line Irinotecan, capecitabine (Xeloda®), and Oxaliplatin (IXO). Patients and Methods Eligible patients with HER2-unamplified/unknown, metastatic gastric/GEJ adenocarcinoma were treated with 21-day cycle IXO at dose level 1 (DL1: Day 1 O-100 mg/m2 & I-160 mg/m2 IV, Day 2–15 X-1900 mg/m2/day PO divided doses) or modified IXO (mIXO): Day 1 O-85 mg/m2 & I-120 mg/m2 IV, Day 2–15 X-1425 mg/m2/day PO divided doses). This Bryant and Day two-stage designed study had dual primary endpoints of objective response rate (ORR) and toxicity. Secondary endpoints were overall survival (OS) and progression-free survival (PFS). Results Fifty patients were enrolled and received a median of 7 cycles. After accrual of 9 patients at DL1, evaluable RR was 88% however dose limiting toxicity (DLT) rate was 56% thus doses were adjusted to mIXO. Fifteen patients accrued at mIXO had a RR of 60% and DLT rate of 13% allowing continuation to stage 2. Overall, 48 and 49 patients were evaluable for efficacy and safety, respectively, with ORR of 54% and DLTs in 24% of patients (DL1 = 56%; mIXO = 18%). Disease control rate was 85%. The most frequent grade 3/4 adverse events were diarrhea, neutropenia, fatigue, hypokalemia, and nausea. Median PFS and OS were 7.5 and 13.0 months, respectively, with a median follow-up of 9.7 months. Conclusion mIXO demonstrates promising ORR, PFS, OS, and acceptable toxicity compared to standard triplet regimens. IXO should be evaluated in phase III trials.

Background: Selection and sequencing of treatment regimens for individual patients with metastatic colorectal cancer (mcrc) is driven by maintaining reasonable quality of life and extending survival, as well as by access to and cost of therapies. The objectives of the present study were to describe, for patients with mcrc, attrition across lines of systemic therapy, patterns of therapy and their timing, and KRAS status. Methods: A retrospective chart review at 6 Canadian academic centres included sequential patients who were diagnosed with mcrc from 1 January 2009 onward and who initiated first-line systemic treatment for mcrc between 1 January and 31 December 2009. Death was included as a competing risk in the analysis. Results: The analysis included 200 patients who started first-line therapy. The proportions of patients who started second-, third-, and fourth-line systemic therapy were 70%, 30%, and 15% respectively. Chemotherapy plus bevacizumab was the most common first-line combination (66%). The most common first-line regimen was folfiri plus bevacizumab. KRAS testing was performed in 103 patients (52%), and 38 of 68 patients (56%, 19% overall) with confirmed KRAS wild-type tumours received an epidermal growth factor receptor inhibitor (egfri), which was more common in later lines. Most KRAS testing occurred after initiation of second-line therapy. Conclusions: In the modern treatment era, a high proportion of patients receive at least two lines of therapy for mcrc, but only 19% receive egfri therapy. Earlier KRAS testing and therapy with an egfri might allow a greater proportion of patients to access all 5 active treatment agents.

3508 Background: CO.28 (NCT03259035) is a phase II study designed to determine if patients with cT1-T3a/bN0 rectal cancer can be treated with induction chemotherapy (FOLFOX/CAPOX) and organ-preserving surgery. Methods: Patients with MRI staged cT1-3a/bN0 tumors and no pathologic (p) high risk features received 6/4 cycles of FOLFOX/CAPOX, repeat sigmoidoscopy/pelvic MRI and subsequent Transanal Endoscopic Surgery (TES) in the absence of tumor progression. ypT0/T1N0 tumors were treated with observation while ypT2+ or ypN+ stage were recommended Total Mesorectal Excision (TME). The primary endpoint was protocol specified Organ Preservation Rate (psOPR = ypT0/T1N0, no p high risk features) and actual Organ Preservation Rate (aOPR = ypT0/T1N0 stage plus higher yp stage patients who declined TME surgery). The study would be considered negative with an psOPR of 50% or lower (H0) and as promising if it is 65% or higher (H1). Results: Between 08/2017 to 05/2020, 58 eligible patients were accrued in Canada and the United States, median age was 67 years, 71% male. All had well-moderately differentiated, non-mucinous rectal adenocarcinoma and median tumor height was 6 cm (range 0-18). Median follow-up was 15.4 months. Chemotherapy with FOLFOX (32) or CAPOX (26) was administered, 90% completed all planned cycles. A total of 56/58 (97%) proceeded to TES, while one patient was ineligible due to tumor progression (1.7%) and one declined. In the intention to treat analysis, the psOPR was 57% (95% CI 43-70%) while the aOPR was 79% (95% CI 67% to 89%) due to 13/23 declining recommended TME surgery. Of 10 patients who proceeded to recommended TME, a complete R0 TME was performed in 9/10, and no p residual carcinoma was found in 7/10. Crude loco-regional (LR) and distant recurrence rates were 3.5% (95% CI 0.4 to 12%) and 0%, respectively. A recurrence occurred in 1/13 patients who initially declined TME surgery. Conclusions: In select patients with early stage rectal cancer, three months of induction CAPOX/FOLFOX followed by TES resulted in a high OPR without the use of pelvic irradiation. The observed high rate of pathologic downstaging may point to high chemo-responsiveness in early rectal adenocarcinoma with no p high risk features. Further trials to evaluate this approach are justified and updated results will be presented. Clinical trial information: NCT03259035. [Table: see text]

BACKGROUND Patient-reported outcomes (PROs) are increasingly used in clinical settings. Prior research suggests that PROs collected at baseline may be associated with cancer survival, but most of those studies were conducted in patients with breast or lung cancer. The objective of this study was to determine the correlation between prospectively collected PROs and cancer-specific outcomes in patients with early stage colorectal cancer. METHODS Patients who had newly diagnosed stage II or III colorectal cancer from 2009 to 2010 and had a consultation at the British Columbia Cancer Agency completed the brief Psychosocial Screen for Cancer (PSSCAN) questionnaire, which collects data on patients' perceived social supports, quality of life (QOL), anxiety and depression, and general health. PROs from the PSSCAN were linked with the Gastrointestinal Cancers Outcomes Database, which contains information on patient and tumor characteristics, treatment details, and cancer outcomes. Cox regression models were constructed for overall survival (OS), and Fine and Gray regression models were developed for disease-specific survival (DSS). RESULTS In total, 692 patients were included. The median patient age was 67 years (range, 26-95 years), and the majority had colon cancer (61%), were diagnosed with stage III disease (54%), and received chemotherapy (58%). In general, patients felt well supported and reported good overall health and QOL. On multivariate analysis, increased fatigue was associated with worse OS (hazard ratio [HR], 1.99; P = .00007) and DSS (HR, 1.63; P = .03), as was lack of emotional support (OS: HR, 4.36; P = .0003; DSS: HR, 1.92; P = .02). CONCLUSIONS Although most patients described good overall health and QOL and indicated that they were generally well supported, patients who experienced more pronounced fatigue or lacked emotional support had a higher likelihood of worse OS and DSS. These findings suggest that abbreviated PROs can inform and assist clinicians to identify patients who have a worse prognosis and may need more vigilant follow-up. Cancer 2017;123:1839–1847. © 2017 American Cancer Society.

Objectives Optimal treatment of rectal cancer (RC) requires multidisciplinary care. We examined whether distance to treatment center or community size impacts access to multimodality care and population-based outcomes in RC. Methods Patients diagnosed with stage II/III RC from 1999 to 2009 and treated at 1 of 6 regional cancer centers in British Columbia were reviewed. Distance to treatment center was determined for each patient. Communities were classified as rural, small, medium, and large population centers. Logistic and Cox regression models assessed associations of distance and community size with treatment received as well as cancer-specific (CSS) and overall survival (OS). Results Of 3,158 patients, 93.6% underwent surgery, 86.3% received radiotherapy, and 51.3% were treated with adjuvant chemotherapy (AC). Median time from diagnosis to oncologic consultation was longer for those >100 km from a treatment center or residing in medium/rural communities. Logistic regression demonstrated no correlation between distance or community size and receipt of treatment modality. Univariate analysis showed similar CSS (P = .18, .88) and OS (P = .36, .47) based on community size and distance, respectively. In multivariate analysis, distance >100 km had inferior CSS (Hazard Ratio [HR] 1.39, 95% CI: 1.03-1.88; P = .031). There was no consistent trend between decreasing community size and outcomes; however, living in a small center was associated with improved OS (HR 0.58, 95% CI: 0.38-0.88; P = .011) and CSS (HR 0.42, 95% CI: 0.25-0.70; P = .001). Conclusions In this population-based study, there were no urban-rural differences in access to multidisciplinary care, but increased distance may be associated with worse cancer-specific outcomes.

61 Background: Pembrolizumab was recently granted tissue agnostic FDA accelerated approval for metastatic cancers with TMB≥10 mut/Mb. However, limited data supports immunotherapy in microsatellite stable (MSS) mCRC with TMB≥10 mut/Mb. We assessed tissue TMB and contrasted it to plasma derived TMB in the CO.26 trial. Methods: CO.26 was a phase 2 trial (2-sided ⍺ = 0.1 and 80% power) that randomized 180 patients (pts) 2:1 to D+T or BSC in refractory mCRC. Pre-treatment plasma was sequenced with the GuardantOMNI assay and archival tissue underwent exome sequencing with TMB assessed per the TMB harmonization project. MSI-H cases were excluded. For plasma TMB, we used a previously published cut point (≥28). Results: Overall survival (OS) but not progression free survival (PFS) was improved with D+T in the entire population. Of 180 pts, 163 were evaluable for plasma and 110 for tissue TMB. Median time between archival tissue and plasma collection was 3.1 yrs (IQR 1.9-5.1). Median tissue TMB was 6.6 muts/Mb (IQR 4.1-12.0), while median plasma TMB was 16.3 muts/Mb (IQR 9.4-25.9). Tissue and plasma TMB (r = -0.039, P = 0.69) were not correlated. Tissue TMB≥10 was not prognostic in the BSC arm (HR 1.01, 90%CI 0.52-1.92, P = 0.99) and OS was not improved in pts with tissue TMB≥10 (32/110 pts) following D+T vs BSC. A test of interaction suggested this threshold was not predictive (P = 0.85). Using a minimum P-value approach, no threshold supported high tissue TMB as predictive in MSS mCRC. In fact, the optimal cut point suggested low tissue TMB ( < 4.1 muts/Mb) had the greatest benefit from D+T (P-interaction = 0.048) and pts with TMB ≥4.1 mut/Mb (HR 0.50, 90%CI 0.26-0.96, P = 0.083) trended to better OS in the BSC arm. In contrast, 35/163 pts (21%) were identified in a high plasma TMB group associated with worse OS (HR 2.56, 90%CI 1.45-4.54, P = 0.007) in the BSC arm but improved OS following D+T compared to BSC with P-interaction = 0.082. Only 1 response was noted following D+T in a pt with tissue TMB = 16 mut/Mb and plasma TMB = 13 mut/Mb. Conclusions: Archival tissue TMB≥10 mut/Mb does not appear predictive of D+T benefit in MSS mCRC. Plasma derived TMB may better reflect evolutionary changes following intervening therapy than archival tissue. Clinical trial information: NCT02870920. [Table: see text]

32 Background: Trimodality therapy (TT) remains standard for stage 2/3 rectal cancer and emerging evidence supports better outcomes with total neoadjuvant therapy (TNT) than similar therapy given post-operatively (Post-op). Real-world practice patterns and sequence of TT have significant implications on rectal cancer quality of care, outcomes and clinical trial design, and are not well described. Methods: The National Cancer Database was used to identify patients with clinical (c) stage 2/3 rectal adenocarcinoma diagnosed between 2006-2016, while pathologic (p) stage 2/3 was used when c stage was missing. Patients were included if they received Chemo/Radiation (C/RT), single or multiagent (SA or MA) chemotherapy (CT) and surgery. TNT was defined as receipt of pre-op C/RT and MA CT and no post-op therapy. Survival analyses were performed using Kaplan-Meier (KM) estimates and Cox univariate and multivariate hazard ratios (HRs) adjusted for TNT group, sex, race, year of diagnosis, stage, facility type, and age of diagnosis. Five-year KM survival proportions were limited to years 2006-2012, while Cox HRs were estimated from 2006 to 2015. Results: Of 32,467 patients who received TT, 8883 (27%) received TNT and 23,584 were classified no-TNT. TNT and no-TNT cohorts were numerically similar in age, race and gender. A significantly higher proportion of pStages 0-2 patients were observed in the TNT vs the no-TNT cohorts (61% vs. 48%, p < .001). In analysis of annual treatment patterns of the whole cohort, a gradual reduction in Post-op C/RT was observed between 2006 (28%) and 2016 (8%, p < .001), while use of TNT and MA CT did not increase. A migration to lower pStages 0/1/2/3 was seen between 2006 (1/10/31/57%, respectively) and 2016 (3/22/29/45%) (2016) (p < .001). Five-year OS analysis showed superior OS for Pre-op vs Post-op C/RT (74 vs 69%, HR = .81, p < .001), and MA CT vs. SA CT (76 vs 71%, HR = 0.79, p < .001) but inferior 5-y OS for the TNT vs. no-TNT cohorts (74 vs 78%, HR = 1.17, p < .001). Conclusions: Between 2006-16, a minority of patients treated with TT for stage 2/3 rectal cancer received TNT which did not increase over time. Significant annual shifts from Post-op C/RT to Pre-op C/RT, and migration to lower pStages were seen during this time period. Pre-op C/RT and MA CT were associated with improved OS, while TNT patients experienced inferior OS vs. the no-TNT cohort, possibly related to confounding factors in this observational cohort; multivariate sub-group analysis to be presented. Emerging evidence in support of TNT may further change treatment patterns and outcomes. [Table: see text]

117 Background: Previous studies have identified MAPK and PIK3CA/AKT/mTOR pathways as common mechanisms of acquired resistance to anti-EGFR antibodies (EGFRab) in mCRC. However, such alterations do not account for all patients that become treatment resistant. Using paired whole-exome (WES; tissue) and circulating tumor DNA (ctDNA; plasma) sequencing, we performed characterization of the EGFRab resistance landscape in patients with mCRC. Methods: Post-treatment (ctDNA; plasma) sequencing was performed for 169 patients with mCRC, with 112 (66%) patients also receiving pre-treatment (WES; primary tumor) sequencing as part of the CO.26 trial. 66 (39%) patients received EGFRab previously at a median of 132.0 days prior to plasma sampling. Using bespoke bioinformatics pipelines (WES) coupled with the GuardantOMNI assay (plasma), we compared somatic mutation (SNV/indel, CNV and fusion) frequencies between pre- and post-EGFRab timepoints, and contrasted results between the two groups. Results: Significant increases in de novo acquisition of EGFR (p = 5.6e-4), KRAS (p = 0.011), ZNF217 (p = 0.0022), MAP2K1 (p = 0.0078) and LRP1B (p = 0.017) SNV/indels were unique to the EGFRab group and often occurred as multiple, low allele frequency events in the same patient. De novo copy number amplification of known resistance genes EGFR/ BRAF/ MET were observed in EGFRab-treated patients (p < 0.05), along with SMO (p = 6.8e-7), PTEN inhibitory gene PREX2 (p = 5.6e-4), FLT3 (p = 2.0e-5), NOTCH4 (p = 6.3e-5), ERBB2 (7.4e-4), KMT2A (p = 3.7e-4) and ARID1B (p = 0.0014). Genes impacted by fusion events in EGFRab-treated patients included BRAF-KIAA1549 (1 patient) and MET-CAV1 (1 patient), and these events were not detected in matched pre-treatment samples. EGFRab-treated patients were found to acquire a combination of multiple (≥5) mutation events (SNV/indel, CNV or fusion) at much higher frequency compared to non-EGFRab-treated patients (67% versus 25% of patients, p = 8.7e-8). Tumor mutation burden (TMB) was not significantly different (p = 0.71) between treatment groups prior to therapy initiation, while post-treatment TMB was significantly higher (p = 1.8e-7) in EGFRab-treated patients (median 25.4 versus 13.1 mut/mb). Conclusions: In addition to previously established resistance pathways, we identified acquired alterations in additional genes such as SMO, PREX2 and epigenetic modifiers KMT2A/ARID1B in EGFRab-treated patients . Moreover, we highlight the phenomenon by which EGFRab-treated tumors acquire multiple concurrent resistance mutations and heightened TMB. Our analysis provides novel insight into the landscape of resistance mechanisms to EGFRab in mCRC while highlighting the potential role for immunotherapy post-EGFRab. Clinical trial information: NCT02870920.

Single-agent immune checkpoint inhibition has not shown activities in advanced refractory colorectal cancer (CRC), other than in those patients who are microsatellite-instability high (MSI-H).To evaluate whether combining programmed death-ligand 1 (PD-L1) and cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) inhibition improved patient survival in metastatic refractory CRC.A randomized phase 2 study was conducted in 27 cancer centers across Canada between August 2016 and June 2017, and data were analyzed on October 18, 2018. Eligible patients had histologically confirmed adenocarcinoma of the colon or rectum; received all available standard systemic therapies (fluoropyrimidines, oxaliplatin, irinotecan, and bevacizumab if appropriate; cetuximab or panitumumab if RAS wild-type tumors; regorafenib if available); were aged 18 years or older; had adequate organ function; had Eastern Cooperative Oncology Group performance status of 0 or 1, and measurable disease.We randomly assigned patients to receive either 75 mg of tremelimumab every 28 days for the first 4 cycles plus 1500 mg durvalumab every 28 days, or best supportive care alone (BSC) in a 2:1 ratio.The primary end point was overall survival (OS) and a 2-sided P.10 was considered statistically significant. Circulating cell-free DNA from baseline plasma was used to determine microsatellite instability (MSI) and tumor mutation burden (TMB).Of 180 patients enrolled (121 men [67.2%] and 59 women [32.8%]; median [range] age, 65 [36-87] years), 179 were treated. With a median follow-up of 15.2 months, the median OS was 6.6 months for durvalumab and tremelimumab and 4.1 months for BSC (hazard ratio [HR], 0.72; 90% CI, 0.54-0.97; P = .07). Progression-free survival was 1.8 months and 1.9 months respectively (HR, 1.01; 90% CI, 0.76-1.34). Grade 3 or 4 adverse events were significantly more frequent with immunotherapy (75 [64%] patients in the treatment group had at least 1 grade 3 or higher adverse event vs 12 [20%] in the BSC group). Circulating cell-free DNA analysis was successful in 168 of 169 patients with available samples. In patients who were microsatellite stable (MSS), OS was significantly improved with durvalumab and tremelimumab (HR, 0.66; 90% CI, 0.49-0.89; P = .02). Patients who were MSS with plasma TMB of 28 variants per megabase or more (21% of MSS patients) had the greatest OS benefit (HR, 0.34; 90% CI, 0.18-0.63; P = .004).This phase 2 study suggests that combined immune checkpoint inhibition with durvalumab plus tremelimumab may be associated with prolonged OS in patients with advanced refractory CRC. Elevated plasma TMB may select patients most likely to benefit from durvalumab and tremelimumab. Further confirmation studies are warranted.ClinicalTrials.gov Identifier: NCT02870920.

Background Resistance to Epidermal Growth Factor inhibition (EGFRi) in patients with KRAS wild-type (wt) Colorectal Cancer (CRC) may occur as a result of PI3K/AKT/mTOR signaling. We conducted a study to establish the recommended phase II dose (RP2D) and response rate of panitumumab, an EGFRi, plus BKM120, a PI3K inhibitor, in advanced CRC. Methods Patients with chemotherapy refractory KRAS wt CRC, who were EGFRi naive were enrolled. A 3 + 3 dose escalation design was utilized. The starting dose of panitumumab was 6 mg/kg iv every 2 weeks with BKM120 at 60 mg oral daily. Results Nineteen patients were treated and 17 were evaluable for response. The starting dose was not tolerable (mucositis, fatigue). At dose level (DL) 1, three of six patients discontinued treatment due to toxicity, DL − 1 had no significant toxicity. Panitumumab 6 mg/kg iv q 2 weeks with BKM120 60 mg given 5 out of 7 days per week was declared the RP2D. One patient (5.9%) who was PTEN and PIK3CA negative by IHC had a partial response, seven had stable disease, and nine had disease progression. Conclusion Panitumumab (6 mg/kg iv q 2 weeks) with BKM120 60 mg given 5 out of 7 days per week was declared the RP2D. Toxicities including fatigue, rash and mucositis. There was little evidence of activity in this biomarker unselected cohort.

e19222 Background: Use of EOL CTx is an established quality metric in patients with advanced malignancies but less is known about which types of CTx are most commonly used and association with ED and ICU utilization. We sought to describe the different types of EOL CTx and to quantify the frequency of EOL ED and ICU care associated with them. Methods: Patients in the cancer registry of an urban cancer center who died between January 1, 2018 and October 10, 2019, and ever received CTx were included. EOL CTx was defined as any CTx given within 30 days of death, while any ED visits or ICU admissions in the last 30 days of life were defined as EOL ED and ICU care, respectively. CTx was categorized by administration route (intravenous (IV), oral (PO), other), and by type (immunotherapy (IMT), non-immunotherapy biologics (NIB), other). We used Pearson’s chi-squared to measure associations between EOL CTx and EOL ED and ICU care, logistic regression to assess how CTx type modulates those associations, and Mood’s median test to compare median IMT doses between groups. Results: Among 390 eligible patients, 32% received EOL CTx, 30% EOL ED care, and 11% EOL ICU care. Most received IV CTx (78%), and 10% received IMT. Median age at diagnosis was 69 years (interquartile range (IQR) 62 - 77), and median days from diagnosis to death was 390 (IQR 185 - 665). Most common malignancies were pancreatobiliary (40%), other gastrointestinal (15%), lung (13%) and hematologic (6%). Patients treated with EOL CTx were significantly more likely to receive IMT (p = 0.03). Receipt of any EOL CTx was significantly associated with EOL ED care (p < 0.0001) and EOL ICU care (p < 0.0001). Subgroup analyses showed significant modulatory effect of IMT on association of EOL CTx with EOL ED care (b = -0.89, p = 0.046), but was not significant for ICU care (b = -0.67, p = 0.29). Median doses of IMT was 2.5 (IQR 2 - 3.8) among patients who were given EOL IMT and 4 doses (IQR 2 - 6) in those that discontinued IMT before EOL (p = 0.06). Conclusions: EOL CTx is associated with significantly increased rates of EOL ED and ICU care, which may indicate poorer quality of life. While rates of use of other CTx modalities did not significantly differ at EOL, patients were more likely to receive IMT within 30 days of death, which could be due to the belief that IMT is more tolerable or more effective than other CTx modalities at EOL. IMT at EOL is associated with a reduced risk of EOL ED care, but not ICU care. Further research on strategies to reduce EOL CTx and appropriateness of IMT at EOL is warranted.

Recurrent activating point mutations in KRAS are critical drivers in pancreatic cancer and have been attributed to resistance to anti–epidermal growth factor receptor therapy in colorectal cancer. Although KRAS genotyping provides limited clinical utility in the diagnosis and management of pancreatic cancer patients at present, inferences about the fractional abundance of KRAS mutations may inform on tumor purity in traditionally challenging clinical specimens and their potential use in precision medicine. KRAS genetic testing has indeed become an essential tool to guide treatment decisions in colorectal cancer, but an unmet need for methods standardization exists. Here, we present a unique droplet digital PCR method that enables the simultaneous detection and quantification of KRAS exon 2, 3, and 4 point mutations and copy number alterations. We have validated 13 mutations (G12S, G12R, G12D, G12A, G12V, G12C, G13D, G60V, Q61H, Q61L, A146V, A146T, and A146P) and focal KRAS amplifications by conducting this assay in a cohort of 100 DNA samples extracted from fresh frozen tumor biopsies, formaldehyde-fixed, paraffin-embedded tissue, and liquid biopsy specimens. Despite its modest lower limit of detection (approximately 1%), this assay will be a rapid cost-effective means to infer the purity of biopsy specimens carrying KRAS mutations and can be used in noninvasive serial monitoring of circulating tumor DNA to evaluate clinical response and/or detect early signs of relapse.

Background We previously showed pTMB selects patients (pts) deriving benefit from PD-L1 and CTLA-4 inhibition with durvalumab and tremelimumab (D+T) compared to best supportive care (BSC) in refractory mCRC in CCTG CO.26. Methods We investigated somatic variants contributing to pTMB in MSS pts using cell-free DNA (cfDNA) analysis performed with the GuardantOMNITMassay (2.1Mb) on 166 pts from CO.26. Results Median pTMB was 16.3 mutations/megabase (mts/Mb). Using a minimum p-value approach, pts with pTMB>28 mts/Mb (21% of MSS pts) had the greatest overall survival (OS) benefit for D + T (HR 0.34, 90% CI 0.18-0.63, p-interaction=0.070) and worse OS in the BSC arm (HR 2.59, 90% CI 1.46-4.62). Of 4044 mts detected, 2718 (67.2%) were subclonal ( 10.6 mts/Mb (14.1% pts). Similarly, pTMB calculated using only subclonal mts associated with D+T OS benefit (HR 0.32, 90% CI 0.16-0.67, p-interaction=0.057). Though many genes were associated with pTMB and improved efficacy (see Table), only BRCA1 mts predicted treatment effect (p-interaction=0.035). Most DNA repair mts were subclonal and not associated with increased clonal pTMB. Table . 528PD Gene Mutation Median pTMB MT vs WT Median Clonal pTMB MT vs WT HR (90% CI, p) Among Pts with Selected MT MSS Study Population (n = 166) 16.3 (95% CI: 14.4-20.1) 5.8 (95% CI: 4.8-5.8) 0.66 (0.49-0.89, 0.024) BRCA1 (n = 21) 23.0 vs 15.3 (P = 0.0006) 5.8 vs 5.8 (P = 0.64) 0.20 (0.07-0.58, 0.013) BRCA2 (n = 29) 28.9 vs 14.6 (P 5.8 vs 5.8 (P = 0.52) 0.39 (0.18-0.85, 0.047) ATM (n = 31) 31.6 vs 13.9 (P 6.7 vs 4.8 (P = 0.023) 0.66 (0.37-1.18, 0.24) Polymerase E/D1/Q/H (n = 20) 36.4 vs 14.7 (P 5.3 vs 5.8 (P = 0.57) 0.95 (0.44-2.05, 0.91) TP53 (n = 126) 17.2 vs 13.1 (P = 0.024) 4.8 vs 6.7 (P = 0.017) 0.63 (0.45-0.88, 0.024) MMR Gene without MSI (n = 31) 24.9 vs 14.6 (P 5.8 vs 5.8 (P = 0.85) 0.38 (0.17-0.85, 0.050) Conclusions Both clonal and subclonal mts causing an elevated pTMB associated with benefit from D+T and mts in select DNA repair genes may correlate with benefit. cfDNA provides an opportunity to evaluate tumor evolution potentially missed in archival tissue. Clinical trial identification NCT02870920. Legal entity responsible for the study Canadian Cancer Trials Group. Funding Canadian Cancer Society. Disclosure P.Z. Brohawn: Shareholder / Stockholder / Stock options, Full / Part-time employment: AstraZeneca. K. Banks: Shareholder / Stockholder / Stock options, Licensing / Royalties, Full / Part-time employment: Guardant Health. K. Quinn: Shareholder / Stockholder / Stock options, Licensing / Royalties, Full / Part-time employment: Guardant Health. All other authors have declared no conflicts of interest.