NCI Rectal-Anal Task Force consensus recommendations for design of clinical trials in rectal cancer

The optimal management of locally advanced rectal cancer is rapidly evolving. The National Cancer Institute Rectal-Anal Task Force convened an expert panel to develop consensus on the design of future clinical trials of patients with rectal cancer. A series of 82 questions and subquestions, which addressed radiation and neoadjuvant therapy, patient perceptions, rectal cancer populations of special interest, and unique design elements, were subject to iterative review using a Delphi analytical approach to define areas of consensus and those in which consensus is not established. The task force achieved consensus on several areas, including the following: 1) the use of total neoadjuvant therapy with long-course radiation therapy either before or after chemotherapy, as well as short-course radiation therapy followed by chemotherapy, as the control arm of clinical trials; 2) the need for greater emphasis on patient involvement in treatment choices within the context of trial design; 3) efforts to identify those patients likely, or unlikely, to benefit from nonoperative management or minimally invasive surgery; 4) investigation of the utility of circulating tumor DNA measurements for tailoring treatment and surveillance; and 5) the need for identification of appropriate end points and recognition of challenges of data management for patients who enter nonoperative management trial arms. Substantial agreement was reached on priorities affecting the design of future clinical trials in patients with locally advanced rectal cancer.

Liver Metastases and Immune Checkpoint Inhibitor Efficacy in Patients With Refractory Metastatic Colorectal Cancer: A Secondary Analysis of a Randomized Clinical Trial

Importance

Immune checkpoint inhibitors (ICIs) have limited activity in microsatellite-stable (MSS) or mismatch repair-proficient (pMMR) colorectal cancer. Recent findings suggest the efficacy of ICIs may be modulated by the presence of liver metastases (LM).

Objective

To investigate the association between the presence of LM and ICI activity in advanced MSS colorectal cancer.

Design, Setting, and Participants

In this secondary analysis of the Canadian Cancer Trials Group CO26 (CCTG CO.26) randomized clinical trial, patients with treatment-refractory colorectal cancer were randomized in a 2:1 fashion to durvalumab plus tremelimumab or best supportive care alone between August 10, 2016, and June 15, 2017. The primary end point was overall survival (OS) with 80% power and 2-sided α = .10. The median follow-up was 15.2 (0.2-22.0) months. In this post hoc analysis performed from February 11 to 14, 2022, subgroups were defined based on the presence or absence of LM and study treatments.

Intervention

Durvalumab plus tremelimumab or best supportive care.

Main Outcomes and Measures

Hazard ratios (HRs) and 90% CIs were calculated based on a stratified Cox proportional hazards regression model. Plasma tumor mutation burden at study entry was determined using a circulating tumor DNA assay. The primary end point of the study was OS, defined as the time from randomization to death due to any cause; secondary end points included progression-free survival (PFS) and disease control rate (DCR).

Results

Of 180 patients enrolled (median age, 65 [IQR, 36-87] years; 121 [67.2%] men; 19 [10.6%] Asian, 151 [83.9%] White, and 10 [5.6%] other race or ethnicity), LM were present in 127 (70.6%). For patients with LM, there was a higher proportion of male patients (94 of 127 [74.0%] vs 27 of 53 [50.9%]; P = .005), and the time from initial cancer diagnosis to study entry was shorter (median, 40 [range, 8-153] vs 56 [range, 14-181] months; P = .001). Plasma tumor mutation burden was significantly higher in patients with LM. Patients without LM had significantly improved PFS with durvalumab plus tremelimumab (HR, 0.54 [90% CI, 0.35-0.96]; P = .08; P = .02 for interaction). Disease control rate was 49% (90% CI, 36%-62%) in patients without LM treated with durvalumab plus tremelimumab, compared with 14% (90% CI, 6%-38%) in those with LM (odds ratio, 5.70 [90% CI, 1.46-22.25]; P = .03). On multivariable analysis, patients without LM had significantly improved OS and PFS compared with patients with LM.

Conclusions and Relevance

In this secondary analysis of the CCTG CO.26 study, the presence of LM was associated with worse outcomes for patients with advanced colorectal cancer. Patients without LM had improved PFS and higher DCR with durvalumab plus tremelimumab. Liver metastases may be associated with poor outcomes of ICI treatment in advanced colorectal cancer and should be considered in the design and interpretation of future clinical studies evaluating this therapy.

Current Practices in Hepatic Artery Infusion (HAI) Chemotherapy: An International Survey of the HAI Consortium Research Network

BACKGROUND

An increasing number of hepatic artery infusion (HAI) programs have been established worldwide. Practice patterns for this complex therapy across these programs have not been reported. This survey aimed to identify current practice patterns in HAI therapy with the long-term goal of defining best practices and performing prospective studies.

METHODS

Using SurveyMonkeyTM, a 28-question survey assessing current practices in HAI was developed by 12 HAI Consortium Research Network (HCRN) surgical oncologists. Content analysis was used to code textual responses, and the frequency of categories was calculated. Scores for rank-order questions were generated by calculating average ranking for each answer choice.

RESULTS

Thirty-six (72%) HCRN members responded to the survey. The most common intended initial indications for HAI at new programs were unresectable colorectal liver metastases (uCRLM; 100%) and unresectable intrahepatic cholangiocarcinoma (uIHC; 56%). Practice patterns evolved such that uCRLM (94%) and adjuvant therapy for CRLM (adjCRLM; 72%) have become the most common current indications for HAI at established centers. Referral patterns for pump placement differed between uCRLM and uIHC, with most patients referred while receiving second- and first-line therapy, respectively, with physicians preferring to evaluate patients for HAI while receiving first-line therapy for CRLM. Concern for extrahepatic disease was ranked as the most important factor when considering a patient for HAI.

CONCLUSIONS

Indication and patient selection factors for HAI therapy are relatively uniform across most HCRN centers. The increasing use of adjuvant HAI therapy and overall consistency of practice patterns among HCRN centers provides a robust environment for prospective data collection and randomized clinical trials.

Monitoring and Surveillance of Patients with Gastroenteropancreatic Neuroendocrine Tumors Undergoing Radioligand Therapy

Radioligand therapy (RLT) with [177Lu]Lu-DOTA-TATE is a standard of care for adult patients with somatostatin-receptor (SSTR)-positive gastroenteropancreatic neuroendocrine tumors (GEP-NETs). Taking advantage of this precision nuclear medicine approach requires diligent monitoring and surveillance, from the use of diagnostic SSTR-targeted radioligand imaging for the selection of patients through treatment and assessments of response. Published evidence-based guidelines assist the multidisciplinary healthcare team by providing acceptable approaches to care; however, the sheer heterogeneity of GEP-NETs can make these frameworks difficult to apply in individual clinical circumstances. There are also contradictions in the literature regarding the utility of novel approaches in monitoring and surveilling patients with GEP-NETs receiving RLT. This article discusses the emerging evidence on imaging, clinical biochemistry, and tumor assessment criteria in the management of patients receiving RLT for GEP-NETs; additionally, it documents our own best practices. This allows us to offer practical guidance on how to effectively implement monitoring and surveillance measures to aid patient-tailored clinical decision-making.

Preoperative Treatment of Locally Advanced Rectal Cancer

BACKGROUND

Pelvic radiation plus sensitizing chemotherapy with a fluoropyrimidine (chemoradiotherapy) before surgery is standard care for locally advanced rectal cancer in North America. Whether neoadjuvant chemotherapy with fluorouracil, leucovorin, and oxaliplatin (FOLFOX) can be used in lieu of chemoradiotherapy is uncertain.

METHODS

We conducted a multicenter, unblinded, noninferiority, randomized trial of neoadjuvant FOLFOX (with chemoradiotherapy given only if the primary tumor decreased in size by <20% or if FOLFOX was discontinued because of side effects) as compared with chemoradiotherapy. Adults with rectal cancer that had been clinically staged as T2 node-positive, T3 node-negative, or T3 node-positive who were candidates for sphincter-sparing surgery were eligible to participate. The primary end point was disease-free survival. Noninferiority would be claimed if the upper limit of the two-sided 90.2% confidence interval of the hazard ratio for disease recurrence or death did not exceed 1.29. Secondary end points included overall survival, local recurrence (in a time-to-event analysis), complete pathological resection, complete response, and toxic effects.

RESULTS

From June 2012 through December 2018, a total of 1194 patients underwent randomization and 1128 started treatment; among those who started treatment, 585 were in the FOLFOX group and 543 in the chemoradiotherapy group. At a median follow-up of 58 months, FOLFOX was noninferior to chemoradiotherapy for disease-free survival (hazard ratio for disease recurrence or death, 0.92; 90.2% confidence interval [CI], 0.74 to 1.14; P = 0.005 for noninferiority). Five-year disease-free survival was 80.8% (95% CI, 77.9 to 83.7) in the FOLFOX group and 78.6% (95% CI, 75.4 to 81.8) in the chemoradiotherapy group. The groups were similar with respect to overall survival (hazard ratio for death, 1.04; 95% CI, 0.74 to 1.44) and local recurrence (hazard ratio, 1.18; 95% CI, 0.44 to 3.16). In the FOLFOX group, 53 patients (9.1%) received preoperative chemoradiotherapy and 8 (1.4%) received postoperative chemoradiotherapy.

CONCLUSIONS

In patients with locally advanced rectal cancer who were eligible for sphincter-sparing surgery, preoperative FOLFOX was noninferior to preoperative chemoradiotherapy with respect to disease-free survival. (Funded by the National Cancer Institute; PROSPECT ClinicalTrials.gov number, NCT01515787.).

Practical considerations when providing palliative care to patients with neuroendocrine tumors in the context of routine disease management or hospice care

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 the quality of life during a routine, disease-directed care as well as at the end-of-life.

Optimizing the number of variants tracked to follow disease burden with circulating tumor DNA assays in metastatic colorectal cancer

Background

The number of somatic mutations detectable in circulating tumor DNA (ctDNA) is highly heterogeneous in metastatic colorectal cancer (mCRC). The optimal number of mutations required to assess disease kinetics is relevant and remains poorly understood.

Objectives

To determine whether increasing panel breadth (the number of tracked variants in a ctDNA assay) would alter the sensitivity in detecting ctDNA in patients with mCRC.

Design

We used archival tissue sequencing to perform an in silico assessment of the optimal number of tracked mutations to detect and monitor disease kinetics in mCRC using sequencing data from the Canadian Cancer Trials Group CO.26 trial.

Methods

For each patient, 1, 2, 4, 8, 12, or 16 of the most clonal (highest variant allele frequency) somatic variants were selected from archival tissue-based whole-exome sequencing and assessed for the proportion of variants detected in matched ctDNA at baseline, week 8, and progression timepoints.

Results

Data from 110 patients were analyzed. Genes most frequently encountered among the top four highest VAF variants in archival tissue were TP53 (51.9% of patients), APC (43.3%), KRAS (42.3%), and SMAD4 (9.6%). While the frequency of detecting at least one tracked variant increased when expanding beyond variant pool sizes of 1 and 2 in baseline (p = 0.0030) and progression (p = 0.0030) ctDNA samples, we observed no significant benefit to increases in variant pool size past four variants in any of the ctDNA timepoints (p < 0.05).

Conclusion

While increasing panel breadth beyond two tracked variants improved variant re-detection in ctDNA samples from patients with treatment refractory mCRC, increases beyond four tracked variants yielded no significant improvement in variant re-detection.

Circulating Tumor DNA Identifies Diverse Landscape of Acquired Resistance to Anti-Epidermal Growth Factor Receptor Therapy in Metastatic Colorectal Cancer

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.

Neoadjuvant Chemotherapy, Excision, and Observation for Early Rectal Cancer: The Phase II NEO Trial (CCTG CO.28) Primary End Point Results

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.

Interplay of Immunosuppression and Immunotherapy Among Patients With Cancer and COVID-19

Importance

Cytokine storm due to COVID-19 can cause high morbidity and mortality and may be more common in patients with cancer treated with immunotherapy (IO) due to immune system activation.

Objective

To determine the association of baseline immunosuppression and/or IO-based therapies with COVID-19 severity and cytokine storm in patients with cancer.

Design, Setting, and Participants

This registry-based retrospective cohort study included 12 046 patients reported to the COVID-19 and Cancer Consortium (CCC19) registry from March 2020 to May 2022. The CCC19 registry is a centralized international multi-institutional registry of patients with COVID-19 with a current or past diagnosis of cancer. Records analyzed included patients with active or previous cancer who had a laboratory-confirmed infection with SARS-CoV-2 by polymerase chain reaction and/or serologic findings.

Exposures

Immunosuppression due to therapy; systemic anticancer therapy (IO or non-IO).

Main Outcomes and Measures

The primary outcome was a 5-level ordinal scale of COVID-19 severity: no complications; hospitalized without requiring oxygen; hospitalized and required oxygen; intensive care unit admission and/or mechanical ventilation; death. The secondary outcome was the occurrence of cytokine storm.

Results

The median age of the entire cohort was 65 years (interquartile range [IQR], 54-74) years and 6359 patients were female (52.8%) and 6598 (54.8%) were non-Hispanic White. A total of 599 (5.0%) patients received IO, whereas 4327 (35.9%) received non-IO systemic anticancer therapies, and 7120 (59.1%) did not receive any antineoplastic regimen within 3 months prior to COVID-19 diagnosis. Although no difference in COVID-19 severity and cytokine storm was found in the IO group compared with the untreated group in the total cohort (adjusted odds ratio [aOR], 0.80; 95% CI, 0.56-1.13, and aOR, 0.89; 95% CI, 0.41-1.93, respectively), patients with baseline immunosuppression treated with IO (vs untreated) had worse COVID-19 severity and cytokine storm (aOR, 3.33; 95% CI, 1.38-8.01, and aOR, 4.41; 95% CI, 1.71-11.38, respectively). Patients with immunosuppression receiving non-IO therapies (vs untreated) also had worse COVID-19 severity (aOR, 1.79; 95% CI, 1.36-2.35) and cytokine storm (aOR, 2.32; 95% CI, 1.42-3.79).

Conclusions and Relevance

This cohort study found that in patients with cancer and COVID-19, administration of systemic anticancer therapies, especially IO, in the context of baseline immunosuppression was associated with severe clinical outcomes and the development of cytokine storm.

Trial Registration

ClinicalTrials.gov Identifier: NCT04354701.

Patterns of Practice and Improvements in Survival Among Patients With Stage 2/3 Rectal Cancer Treated With Trimodality Therapy

Question

How has trimodality therapy and survival for patients with stage 2/3 rectal cancer changed in the US?

Findings

This cohort study of 32 467 patients in the National Cancer Database (2006-2016) found that the use of postoperative chemotherapy/radiation therapy decreased (28% vs 8%), while preoperative chemotherapy/radiation therapy and multiagent chemotherapy increased (24% vs 45%). A migration to lower pathologic stage occurred as well as a significant improvement in survival.

Meaning

Greater use of perioperative therapy for stage 2/3 rectal cancers was associated with significant survival improvement in the clinical setting.

Importance

This 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.

Objective

To 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 Participants

This 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.

Exposures

Trimodality 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 Measures

Using 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%]).

Results

The 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 < .001), and more preoperative C/RT and postoperative MA chemotherapy (group C) (24% vs 45%; P < .001) being used. While clinical stage 2 and 3 distribution remained unchanged, pathologic downstaging was observed to stages 0, 1, 2, and 3: 0.60%, 10%, 31%, and 57% vs 2.8%, 22%, 29%, and 45%, from 2006 to 2015, respectively (P < .001). More recent year of diagnosis was associated with an adjusted hazard ratio of 0.77 (95% CI, 0.67-0.87) for mortality within 36 months after diagnosis (2015 vs 2006).

Conclusions and Relevance

In 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.

Contemporary, national patterns of surgery after preoperative therapy for stage II/III rectal adenocarcinoma

BACKGROUND

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.

AIM

To describe patterns of surgical approach for stage II/III rectal cancer in relation to neoadjuvant therapies.

METHODS

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.

RESULTS

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% vs 84.7%, P < 0.001), but had similar rates of total neoadjuvant therapy (TNT) (27.0% vs 27.2%, P = 0.697). Overall rates of total mesorectal excision without sphincter preservation were similar between clinical stage II and III (30.0% vs 30.3%) and similar if preoperative treatment was chemoradiation (31.3%) or TNT (30.2%). Over the study period, proportion of cases approached laparoscopically increased from 24.9% to 32.5% and robotically 5.6% to 30.7% (P < 0.001). This cohort showed improved survival for MIS approaches compared to open surgery (laparoscopy HR 0.85, 95%CI 0.78-0.93, and robotic HR 0.82, 95%CI 0.73-0.92).

CONCLUSION

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.

Everolimus with or without bevacizumab in advanced pNET: CALGB 80701 (Alliance)

Treatment with the MTOR inhibitor everolimus improves progression-free survival (PFS) in pancreatic neuroendocrine tumors (pNETs), 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 pNETs. One hundred and fifty patients were randomized to receive everolimus 10 mg daily with or without bevacizumab 10 mg/kg i.v. every 2 weeks. Patients also received standard dose of octreotide in both arms. The primary endpoint was PFS, 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; hazard ratio (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 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 PFS and higher response rates compared to everolimus in patients with advanced pNETs. 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 pNETs.

Severe Thrombocytopenia in Patients With Advanced Neuroendocrine Tumor Treated With Peptide Receptor Radioligand Therapy

BACKGROUND

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.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

The Impact of Chronic Kidney Disease in Patients With Locally Advanced Rectal Cancer Treated With Neoadjuvant Chemoradiation

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% <60 mL/min (n = 136). There was no significant difference in the completion rate of neoadjuvant chemotherapy (82% vs 85%, p = 0.36) or radiotherapy (93% vs 95%, p = 0.45) between patients with and without chronic kidney disease. Patients with chronic kidney disease were less likely to receive adjuvant chemotherapy (63% vs 77%, p < 0.01). On multivariate analysis, patients with chronic kidney disease had decreased disease-free survival (HR, 1.37; 95% CI, 1.03-1.82; p = 0.03) but not overall survival (HR, 1.23; 95% CI, 0.88-1.75; p = 0.23) or pathologic complete response (OR, 0.83; 95% CI, 0.50-1.39; p = 0.71).

LIMITATIONS

This study was limited by its retrospective design and by limited events for overall survival analysis.

CONCLUSIONS

In patients with locally advanced rectal cancer undergoing neoadjuvant chemoradiation, baseline chronic kidney disease was associated with less use of adjuvant chemotherapy and decreased disease-free survival. Chronic kidney disease was not independently associated with neoadjuvant chemotherapy/radiotherapy completion rate, pathologic complete response, or overall survival. These data suggest that patients with locally advanced rectal cancer with chronic kidney disease may have distinct outcomes and, accordingly, the results of landmark clinical trials may not be generalizable to this population. See Video Abstract at http://links.lww.com/DCR/B694.

LA REPERCUSIN DE LA ENFERMEDAD RENAL CRNICA EN PACIENTES CON CNCER DE RECTO LOCALMENTE AVANZADO TRATADOS CON QUIMIORRADIOTERAPIA NEOADYUVANTE

ANTECEDENTES:Los pacientes con enfermedad renal crónica generalmente se excluyen de los ensayos clínicos. La repercusión de la enfermedad renal crónica en el desenlace en pacientes con cáncer de recto localmente avanzado no se ha estudiado previamente.OBJETIVO:Investigar la repercusión de la enfermedad renal crónica en los desenlaces en pacientes con cáncer de recto localmente avanzado.DISEÑO:Estudio de cohorte retrospectivo multiinstitucional.ESCENARIO:Centros oncológicos académicos y comunitarios que participan en la base de datos de cáncer rectal del consorcio CHORD.PACIENTES:Pacientes consecutivos con cáncer de recto localmente avanzado, tratados con quimiorradioterapia neoadyuvante, previa a la cirugía con intención curativa del 2005 al 2013.PRINCIPALES VARIABLES EVALUADAS:Sobrevida libre de enfermedad, sobrevida global, respuesta patológica completa, tasa de conclusión de quimioterapia / radioterapia neoadyuvante.RESULTADOS:Se incluyeron 1254 pacientes. El promedio de edad fue de 62, y el 29% / 69% tenían enfermedad en estadio clínico II y III, respectivamente. El promedio de la depuración de creatinina estimada fue de 93 mililitros / minuto, con un 11% <60 mililitros / minuto (n = 136). No hubo diferencias significativas en la tasa de conclusión de la quimioterapia neoadyuvante (82% vs 85%, p = 0,36) o radioterapia (93% vs 95%, p = 0,45) entre pacientes con y sin enfermedad renal crónica. Los pacientes con enfermedad renal crónica tenían menos probabilidades de recibir quimioterapia adyuvante (63% contra el 77%, p <0,01). En el análisis multivariado, los pacientes con enfermedad renal crónica tenían una sobrevida libre de enfermedad menor (HR 1,37, IC 95% 1,03-1,82, p = 0,03) pero no en la sobrevida global (HR 1,23, IC 95% 0,88-1,75, p = 0,23) o respuesta patológica completa (OR 0,83, IC 95% 0,50-1,39, p = 0,71).LIMITACIONES:Diseño retrospectivo y acontecimientos limitados para el análisis de sobrevida global.CONCLUSIONES:En pacientes con cáncer de recto localmente avanzado tratados con quimiorradioterapia neoadyuvante, la enfermedad renal crónica de base se asoció con un menor uso de quimioterapia adyuvante y una menor sobrevida libre de enfermedad. La enfermedad renal crónica no se asoció de forma independiente con la tasa de conclusión de la quimioterapia / radioterapia neoadyuvante, la respuesta patológica completa o la sobrevida global. Estos datos sugieren que los pacientes con cáncer de recto localmente avanzado con enfermedad renal crónica pueden tener resultados distintos y, en consecuencia, los resultados de los ensayos clínicos de referencia pueden no ser generalizables a esta población. Consulte Video Resumen en http://links.lww.com/DCR/B694.

Changes in Carcinoid Syndrome Symptoms Among Patients Receiving Telotristat Ethyl in US Clinical Practice: Findings from the TELEPRO-II Real-World Study

BACKGROUND

Inadequately controlled symptoms incur a substantial burden on patients with neuroendocrine tumors and carcinoid syndrome (CS). The effectiveness of telotristat ethyl (TE) with a somatostatin analog for uncontrolled CS diarrhea has been demonstrated in clinical trials and observational studies. TELEPRO-II was a prospective observational study evaluating TE's effectiveness in clinical practice over the first 3 months of treatment.

METHODS

Patients initiating TE in 2018 participated in an optional nurse support program reporting CS symptoms during interviews at baseline and 1, 2, and 3 months after TE initiation. Eligible patients received TE for ≥3 months and reported symptom burden at baseline and ≥1 follow-up visit within the first 3 months. Daily bowel movement (BM) frequency and flushing episodes were reported as events/episodes per day. Stool consistency, nausea severity, urgency severity, and abdominal pain were reported on a severity scale (1-10). Symptom changes were evaluated using paired-sample t-tests and Wilcoxon signed-rank tests. Analysis of symptoms based on achievement of <30% or ≥30% reduction in daily BM frequency was conducted using a cumulative distribution function.

RESULTS

A total of 684/1603 (43%) patients were eligible for analysis. At baseline, patients reported a mean of 6.3 BM/day, nausea severity of 8.4/10 and stool urgency of 8.2/10. Significant improvements in all CS symptoms were observed after 3 months of TE. Mean daily BMs were reduced 64% after 3 months of TE (mean reduction [SD], -3.99 [3.8]; P<0.0001). Most patients (74%, n=503) reported ≥30% reduction in daily BM frequency; these patients also reported improvements in other symptoms (76-87%). Patients with <30% reduction in daily BMs also reported improvements in nausea severity (62%, n=24), daily flushing episodes (66%, n=98), abdominal pain (50%, n=60), urgency severity (38%, n=64), and stool consistency (24%, n=44).

CONCLUSION

Patients treated with TE in a real-world setting experienced significant, clinically meaningful improvements in CS symptoms.

Impact of new cancer therapies on outpatient treatment delivery for colorectal cancer: A population-based study

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.

Supportive Management of Patients with Advanced Pheochromocytomas and Paragangliomas Receiving PRRT

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.

ctDNA-based mutational landscape following anti-EGFR antibodies in metastatic colorectal cancer (mCRC) to uncover novel resistance mechanisms in the CCTG CO.26 trial

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.

Tissue and plasma tumor mutation burden (TMB) as predictive biomarkers in the CO.26 trial of durvalumab + tremelimumab (D+T) versus best supportive care (BSC) in metastatic colorectal cancer (mCRC)

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]

Changes in treatment and outcomes of stage II/III rectal cancer patients treated with trimodality therapy (TT) between 2006-2016: An NCDB analysis

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]

The Use of Peptide Receptor Radionuclide Therapy in Patients With Neuroendocrine Tumor Cardiac Metastases

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.

ctDNA applications and integration in colorectal cancer: an NCI Colon and Rectal-Anal Task Forces whitepaper

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.

Efficacy and Prognostic Factors for Y-90 Radioembolization (Y-90) in Metastatic Neuroendocrine Tumors with Liver Metastases

Background

Yttrium-90 (Y-90) can be an effective liver-directed therapy for patients with metastatic neuroendocrine tumors (NETs), but population-based data are limited. We characterized the use of Y-90 in NET patients and identified factors associated with response.

Methods

We identified 49 patients with metastatic liver-dominant NETs across BC Cancer's six regional centres who received Y-90 between June 2011 and January 2017 in British Columbia, Canada. Baseline characteristics, radiographic responses, and outcomes were summarized.

Results

Of the 49 patients who received Y-90, the median age was 56 years (range 21-78), 49% were male, and 94% had an ECOG performance status of 0-1. The primary location of the NET included pancreas (31%), small bowel (41%), large bowel (6%), unknown (14%), and others (12%). 69% of these patients had liver metastases alone, and tumors were graded as G1 (61%), G2 (25%), G3 (2%), and unknown (12%). Prior therapies included surgery (63%), local ablative therapy (25%), somatostatin analogue (69%), and systemic therapy (35%). The median Y-90 dose was 2.2 GBq (range 0.8-3.6), as SIR-spheres (69%) or TheraSpheres (29%). Median time to Y-90 from diagnosis of metastases measured 1.54 years. 88% received segmental Y-90, with 1 (69%), 2 (29%), and 3 (2%) treatments. Y-90 resulted in partial response (53%), stable disease (33%), and progressive disease (12%). Y-90 was well-tolerated, with infrequent grade 3-4 biochemical toxicities (2%) and grade 3 abdominal pain (6%). Longer overall survival (OS) was associated with resection of primary tumor, well-differentiated histology, and low Ki-67. Median OS was 27.2 months (95% CI 8.0-46.5).

Conclusions

In our population-based cohort, Y-90 was well-tolerated in patients with metastatic liver-dominant NETs. Prior surgical resection was an important predictor of OS.

Expanded Low Allele Frequency RAS and BRAF V600E Testing in Metastatic Colorectal Cancer as Predictive Biomarkers for Cetuximab in the Randomized CO.17 Trial

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.

Sequence of therapy and survival in patients with advanced pancreatic neuroendocrine tumours

Background

Pancreatic neuroendocrine tumours (pnets) often present as advanced disease. The optimal sequence of therapy is unknown.

Methods

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.

Results

In 66 cases of advanced pnets, median patient age was 61.2 years (25%-75% interquartile range: 50.8-66.2 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.

Conclusions

Our results confirm the primary role of surgery for advanced pnets. New systemic treatments will further increase options.

Effect of Combined Immune Checkpoint Inhibition vs Best Supportive Care Alone in Patients With Advanced Colorectal Cancer: The Canadian Cancer Trials Group CO.26 Study

Importance

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).

Objective

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.

Design, Setting, and Participants

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.

Interventions

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.

Main Outcomes and Measures

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).

Results

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).

Conclusions and Relevance

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.

Trial Registration

ClinicalTrials.gov Identifier: NCT02870920.

Characteristics of end-of-life (EOL) chemotherapy (CTx) received by patients with advanced cancers and association with EOL emergency department (ED) and intensive care unit (ICU) care

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.

Comparison of Treatment, Cost, and Survival in Patients With Metastatic Colorectal Cancer in Western Washington, United States, and British Columbia, Canada

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.

CCTG CO.26: Updated analysis and impact of plasma-detected microsatellite stability (MSS) and tumor mutation burden (TMB) in a phase II trial of durvalumab (D) plus tremelimumab (T) and best supportive care (BSC) versus BSC alone in patients (pts) with refractory metastatic colorectal carcinoma (rmCRC)

3512

Background: Targeting both PD-L1 and CTLA-4 may be synergistic immunotherapy approaches. CO.26 evaluated if dual inhibition leads to improved pt survival vs BSC alone in rmCRC. Methods: rmCRC pts were randomized 2:1 to D+T vs BSC. Treatment consisted of D (1500 mg) D1 q 28 days and T (75 mg) D1 for first 4 cycles, and supportive measures. Primary endpoint was overall survival (OS). Two-sided p < 0.10 was considered statistically significant. Cell-free (cf)DNA sequencing for MSI and TMB used GuardantOMNI panel and baseline plasma. Results: From 08/2016-06/2017, 180 pts were enrolled. Pt characteristics were balanced between arms. At median follow-up of 15.2 months (mos), median OS was 6.6 mos for D+T and 4.1 mos for BSC (p = 0.07; Hazard ratio (HR): 0.72, 90% confidence interval (CI): 0.54 – 0.97). Progression free survival (PFS) was 1.8 mos vs 1.9 mos, respectively (HR 1.01, 90% CI 0.76 – 1.34). Disease control rate (DCR) was 22.6% for D+T and 6.6% for BSC (p = 0.006). cfDNA analysis was successful in 168/169 pts (99.4%). Two pts were MSI-high. In 166 MSS pts, OS HR was 0.66 (p=0.024; 90% CI 0.49-0.89). Excluding the MSI-H cases (TMB of 74.7 and 247.1 mts/Mb), mean TMB was 20.4 ± 16.3 mts/Mb (range: 0.96 – 114.0). In MSS pts, a pre-specified cutpoint of 20 mts/Mb stratified pts into high and low TMB groups but was not predictive for OS , PFS, or DCR (interaction p-values > 0.7). Using a minimum p-value approach, pts with TMB >28 mts/Mb (21% of MSS pts) had the greatest OS benefit (HR 0.34, 90% CI 0.18-0.63) for D+T (interaction p = 0.07). High TMB was associated with a trend in worse prognosis for OS in the BSC arm using both 20 mts/Mb (HR 1.26, 90% CI 0.76-2.12) and 28 mts/Mb (HR 2.59 90% CI 1.46-4.62) cutpoints. Conclusions: D+T significantly prolonged OS in pts with rmCRC. High TMB may select a group of MSS pts who benefit from D+T. Plasma TMB appeared prognostic in the BSC arm. This is the first study showing combined PD-L1 and CTLA-4 inhibition prolongs survival in pts with MSS rmCRC. Updated results based on deaths in more than 90% of pts will be presented. Clinical trial information: NCT02870920.

CO.28: Neoadjuvant Chemotherapy, Excision and Observation (NEO) for early rectal cancer

TPS724

Background: CO.28 is a phase II study which aims to determine if patients with stage I/II rectal cancer can be treated with induction chemotherapy (FOLFOX/CAPOX) and organ-preserving transanal microsurgery. Prior studies have explored the use of pelvic chemoradiation followed by transanal microsurgery as a means to increase organ preservation. However, pre-operative radiation may have acute and prolonged impacts such as wound complications and adverse on sphincter, sexual and urinary function. Moreover, patients who develop recurrence following this strategy are difficult to salvage as re-irradiation is not usually an option. There is virtually no prospective experience of neoadjuvant FOLFOX/CAPOX chemotherapy and excision for early rectal tumors. Methods: The primary objective is to determine the rate of organ preservation and the trial will be successful if more than 65% of patients avoid a formal rectal resection. In this two-staged phase II trial, patients are eligible if they have clinical N0 and T1-T3a/bN0M0 rectal tumors and no pathologic high risk features. After 6 cycles of q2weekly FOLFOX or 4 cycles of CAPOX, rectal endoscopy and pelvic MRI are repeated and if there is evidence of tumor response, patients proceed to tumor excision by Transanal Endoscopic Microsurgery (TEMS) or Transanal Minimally Invasive Surgery (TAMIS). It is required that participating surgeons have a minimum experience of 20 TEMS/TAMIS procedures and they are asked to submit an unedited video for central review. Pathologic ypT0 or ypT1N0 tumors are assigned to observation while ypT2+ or any ypN+ tumors are treated with radical surgery and total mesorectal excision (TME). Pre-operative pelvic radiation is suggested only for ypT3+ or node positive tumors. Endoscopic and cross-sectional imaging is repeated every 4-6 months for 36 months. Circulating tumor DNA (ctDNA) will be correlated with tumor response and relapse. A total of 58 patients will be accrued. Study Progress: The study was activated in Canada in late 2017 and at select US Cancer Centers in 2018, with total accrual to date of 4 patients. (NCT03259035) Clinical trial information: NCT03259035.

Expanded RAS and BRAF V600 testing as predictive biomarkers for single agent cetuximab in the randomized phase III CO.17 trial

537

Background: KRAS/NRAS ( RAS) testing of exons 2, 3 and 4 is standard prior to anti-EGFR treatment in metastatic colorectal cancer and many consider BRAFV600 ( BRAF) mutations predictive. CO.17 was a randomized phase III trial comparing cetuximab vs best supportive care (BSC) in unselected patients (pts). Re-analysis tested only KRAS exon 2, thus the benefit of cetuximab in RAS/BRAF wild type (WT) pts is unclear. Methods: We retrospectively performed expanded RAS/BRAF testing using a highly sensitive digital PCR method (BEAMing; 1% allele frequency detection limit) on micro-dissected archival tissue from 248 CO.17 pts. Additional pts without available archival tissue, with prior Sanger sequencing or therascreen results were included in analyses if mutations were previously detected (n = 77). Overall survival (OS), progression free survival (PFS), and response rates (RR) were compared by molecular profile. Results: Of 248 sequenced pts, 139 (56%) were RAS mutant, with 112 (45%) exon 2, 11 (4%) exon 3 and 6 (2%) exon 4 KRAS mutant, and 10 (4%) NRAS mutant pts. Seven (3%) BRAF mutant, and 97 (30%) confirmed RAS/BRAF WT pts were identified. Results are summarized below. A test of interaction indicated RAS status was predictive for PFS (p = 0.0001) and OS (p = 0.037) and BRAF status neared significance as a predictive marker for PFS (p = 0.089) but not OS (p = 0.24). Conclusions: These updated results demonstrate an improved PFS (HR 0.25 vs 0.40 previously) and OS (HR 0.51 vs 0.55 previously) for cetuximab in RAS/BRAF WT pts compared to prior analyses that included only KRAS exon 2 mutation status. We provide an estimate of single agent cetuximab efficacy for future anti-EGFR re-challenge studies and demonstrate further support that BRAF mutations may predict lack of benefit from anti-EGFR therapy. Clinical trial information: NCT00079066. [Table: see text]

Impact of initial imaging with gallium-68 dotatate PET/CT on diagnosis and management of patients with neuroendocrine tumors (NETs): A sequential case series

379

Background: Somatostatin analogue functional imaging with Ga-68 Dotatate PET/CT has demonstrated superiority in lesion detection in patients with NETs. The effect of this novel imaging modality on US clinical practice and its usefulness in different types of NETs is not well described. We describe the impact of initial NETSPOT imaging on diagnosis and management in NET patients at a large urban medical center. Methods: Consecutive patients diagnosed with NETs and referred to our institution who received an initial Ga-68 Dotatate PET/CT between 07/2017-09/2018 were included. Imaging was reviewed and compared to prior available CT, MRI, and/or In-111 Pentetreotide scans. Results: Among 101 patients, 51/50 were female/male, tumor origins were gastroenteropancreatic (GEP) (75%), Unknown Primary (UP) (13%), lung (8%), thymic (2%), and other (2%). All tumors were histologically well/moderately differentiated and 37/51/3/10 were G1/G2/G3/Unknown, respectively. Initial imaging with Ga-68 Dotatate PET/CT revealed additional metastatic disease in 37 of 77(48%) patients with prior evidence of metastatic disease. Most common sites were distant lymph nodes (18), bone (15) and liver (9), peritoneal/pleural (4). A previously UP tumor was identified in 3 patients. No patients with metastatic lung carcinoids (6 atypical, 2 typical) or thymic NETs (2 atypical/G2) NETs had evidence of Ga-68 Dota PET/CT uptake above reference liver SUV levels. Results of imaging altered patient management as follows: 14 initiated systemic therapy due to documentation of progression, in 6 surgical therapy was altered, in 4 biopsy/other management was changed. In 11 patients with no tumor Ga-68 Dotatate uptake, decisions about use of PRRT and somatostatin analogues was altered. Conclusions: In this series, Ga-68 Dotatate PET/CT altered diagnosis and management in 35/101 NET patients. Among GEP and UP NETs, Dotatate imaging diagnosed primarily new nodal, bone, liver and pleural/peritoneal metastases missed by other imaging modalities. Results support the routine use of Ga-68 Dotatate PET/CT in the care of patients with advanced and early stage NETS.

CCTG CO.26 trial: A phase II randomized study of durvalumab (D) plus tremelimumab (T) and best supportive care (BSC) versus BSC alone in patients (pts) with advanced refractory colorectal carcinoma (rCRC)

481

Background: D is a human monoclonal antibody (mAb) that inhibits binding of programmed cell death ligand 1 (PD-L1) to its receptor. T is a mAb against the cytotoxic T-lymphocyte-associated protein 4 (CTLA-4). Targeting both PD-L1 and CTLA-4 may have additive/synergistic activity as the mechanisms of action of CTLA-4 and PD-L1 inhibition are non-redundant. This study evaluated whether combining PD-L1 and CTLA-4 inhibition would lead to improved pt survival vs BSC alone in rCRC. Methods: Pts with rCRC were randomized 2:1 to D+T vs BSC . Pts were eligible if they failed all standard regimens; containing a fluoropyrimidine, irinotecan and oxaliplatin (and an EGFR inhibitor if Ras wild type). Prior treatment (Tx) with anti-VEGF agents or TAS-102 was permitted but not mandatory. Tx consisted of D (1500 mg) D1 q 28 days and T (75 mg) D1 for first 4 cycles, and all appropriate supportive measures. Primary endpoint was overall survival (OS) and a two-sided p-value < 0.10 was considered statistically significant. Results: Between August 2016 and June 2017, 180 pts were enrolled and 179 treated as randomized. Pt baseline characteristics were balanced. 85% of pts received ≥ 90% of planned doses of D and T. No pts with known defective mismatch repair (dMMR) tumors were enrolled. With a median (med) follow-up of 15.2 months (mo), the med OS was 6.6 mo for D+T and 4.1 mo for BSC (p = 0.07; Hazard ratio (HR): 0.72, 90% confidence interval (CI): 0.54–0.97). Med progression free survival was 1.8 mo and 1.9 mo respectively (HR 1.01, 90% CI 0.76–1.34; p=0.97). Disease control rate was 22.7% for D+T and 6.6% for BSC (p = 0.006). Grade 3/4 abdominal pain, fatigue, lymphocytosis and eosinophilia were significantly higher in D+T. At 16 weeks, there was significantly less deterioration on EORTC QLQ-C30 physical function for D+T. Confirmation of MMR status is ongoing. Conclusions: D+T significantly prolonged OS in pts with rCRC and preserved quality of life. Adverse events were more frequent with D+T. This is the first study showing that combined PD-L1 and CTLA-4 inhibition prolongs survival in pts with advanced refractory CRC not selected for dMMR. Clinical trial information: NCT02870920.

Comparison of chemotherapy use, cost, and survival in patients with metastatic colorectal cancer in Western Washington and British Columbia

LBA3579

Background: Few studies have directly compared health care utilization, costs, and outcomes between geographically similar patients (pts) treated in the U.S.’ multi-payer health system versus Canada’s single-payer system. Using cancer registry and claims data, we assessed systemic therapy (ST) use, cost, and survival for metastatic colorectal cancer (mCRC) pts in Western Washington (WW) and British Columbia (BC). Methods: Pts age ≥ 18 diagnosed with mCRC in 2010 and later were identified from 1) the BC Cancer Agency database and 2) a regional database linking WW SEER to claims from two large commercial insurers. Demographic and treatment characteristics for the two populations were compared using two-sample T tests. ST costs (first-line and lifetime) were expressed as mean per patient per month costs; Canadian costs were expressed in US dollars using the Purchasing Power Parity for Health in 2009. Median survival was reported for both populations. Results: 1622 BC pts and 575 WW pts were included in the analysis. BC pts were more likely to be older (median age 60 vs 66) and male (57% vs 48%, p = < 0.01). A greater proportion of WW versus BC pts received ST (79% vs. 68%, p < 0.01). FOLFIRI plus bevacizumab was the most common first-line regimen in BC (32%) while FOLFOX was the most common first-line regimen in WW (39%). The mean monthly cost of first-line therapy per patient was significantly higher in WW than BC ($12,345 vs $6,195, p = < 0.01), and this was true for all regimens assessed. Mean lifetime monthly ST costs were significantly higher in WW ($7,883 vs $4,830, p = < 0.01). There was no difference in median overall survival between populations among those receiving ST (21.4 months (95% CI 18.0-26.2) in WW and 22.1 months (20.5-23.7) in BC) or among those not receiving ST (5.4 months (2.4-7.7) WW versus 6.3 months (5.2-7.3) BC). Conclusions: Utilization and cost of ST for mCRC was significantly higher for patients in WW compared to BC without differences in overall survival in treated and untreated patients.

Outcomes of Surgical and Chemotherapeutic Treatments of Goblet Cell Carcinoid Tumors of the Appendix

BACKGROUND

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.

METHODS

Patients diagnosed with GCC from 1984 to 2014 were identified from the British Columbia Cancer Agency and the Vancouver Lower Mainland Pathology Archive.

RESULTS

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 < 0.01). Of 19 stage IV patients, 10 (62.5%) received 5-fluorouracil-based chemotherapy and 11 (61%) underwent multiorgan resection (MOR) ± hyperthermic intraperitoneal chemotherapy (HIPEC). Low mitotic rate and MOR ± HIPEC were associated with improved 2-year OS, but only MOR ± HIPEC remained significant on multivariate analysis (hazard ratio 5.4, 95% CI 1.4-20.9; p = 0.015).

CONCLUSIONS

In this population-based cohort, we demonstrate excellent survival outcomes in stage I-III appendiceal GCCs and clinical appendicitis. Hemicolectomy remains the standard treatment. In metastatic disease, outcomes remain poor, although MOR ± HIPEC may improve survival.

Survival Impact of CAPOX Versus FOLFOX in the Adjuvant Treatment of Stage III Colon Cancer

BACKGROUND

Capecitabine and oxaliplatin (CAPOX) and folinic acid, fluorouracil, and oxaliplatin (FOLFOX) are both used in the adjuvant treatment of colon cancer, and while their efficacy is assumed to be similar, they have not been directly compared. We reviewed the toxicity profiles, relative dose intensity (RDI), and survival associated with these regimens across a multi-institutional cohort.

PATIENTS AND METHODS

We identified 394 consecutively treated patients with stage III colon cancer who received an oxaliplatin-containing regimen. RDI was defined as the total dose received divided by the intended total dose if all cycles were received.

RESULTS

FOLFOX was associated with increased mucositis (6.2% vs. 0.7%, P = .0069) and neutropenia (25.9% vs. 8.6%, P < .0001), while CAPOX was associated with increased dose-limiting toxicities (DLTs) (90.7% vs. 80.2%, P = .0055), diarrhea (31.8% vs. 9.0%, P < .0001), and hand-foot syndrome (19.9% vs. 2.1%, P < .0001). Higher median RDI of fluoropyrimidine (93.7% vs. 80.0%, P < .0001) and oxaliplatin (87.2% vs. 76.3%, P < .0001) was noted for patients receiving FOLFOX. Reducing the duration from 6 to 3 months would have prevented 28.7% of FOLFOX and 20.5% of CAPOX patients from ever experiencing a DLT (P = .0008). Overall survival did not differ by regimen (hazard ratio = 0.73; 95% confidence interval 0.45-1.22; P = .24). However, CAPOX was associated with improved disease-free survival (3-year disease-free survival 83.8% vs. 73.4%, P = .022), which remained significant in high-risk (T4 or N2) (P = .039) but not low-risk patients (P = .19).

CONCLUSION

CAPOX may be associated with improved disease-free survival despite greater toxicities and lower RDI. Reducing adjuvant chemotherapy duration to 3 months would prevent 26% of patients from ever experiencing a DLT.

The impact of chronic kidney disease in locally advanced rectal cancer patients treated with neoadjuvant chemoradiation

794

Background: Chronic kidney disease (CKD) and cancer are common with advancing age. CKD may influence drug tolerance/efficacy and is an independent prognostic factor in some cancers. The impact of CKD on outcomes in patients (pts) with locally advanced rectal cancer (LARC) undergoing neoadjuvant chemoradiation (nCRT) has not been previously studied. Methods: We reviewed pts with LARC undergoing nCRT prior to surgery with curative intent from 2005-2013 across 4 Canadian provinces. Data regarding demographics, staging, baseline renal function, treatments and outcome were collected. CKD was defined as having an estimated glomerular filtration rate (eGFR) (Cockroft-Gault) < 60 ml/min. Primary endpoints were neoadjuvant treatment completion rate, disease-free survival (DFS), and overall survival (OS). Logistic regression and Cox proportional hazard models were used to assess for an association between renal function and outcomes. Results: 1122 (71%) of 1580 pts were included for analysis. Median age was 61 (IQR 54-69), 70% male, 84% performance status 0-1. 28% and 68% had clinical stage II and III disease, respectively. Median eGFR was 93 ml/min (IQR 74-114), with 11% < 60 ml/min (n = 120). 97% of all pts received ≥ 44 Gy (median 50 Gy [range 20-80]). 53% received 5-fluorouracil and 44% received capecitabine as neoadjuvant chemotherapy (nCT). 84% completed nCT, 95% completed neoadjuvant radiotherapy (nRT), and 76% received adjuvant chemotherapy (aCT). Pts with CKD were less likely to receive aCT (62% vs 78%; p < 0.01). There was no significant difference in completion rate of nCT (80% vs 85%; p = 0.15) or nRT (93% vs 95%; p = 0.20) based on renal function. After a median follow up time of 62 months, 8% developed local recurrence, 21% developed distant recurrence and 21% have died. 5-year OS and DFS were 78% and 73%, respectively. Pts with CKD had decreased OS on univariate analysis (HR 1.59, 95% CI 1.11-2.28; p = 0.01), but not on multivariate analysis. DFS was not significantly different based on renal function (HR 1.27, 95% CI 0.89-1.81; p = 0.18). Conclusions: In LARC pts undergoing nCRT, CKD was associated with less use of aCT but did not have any independent association with nCT and nRT completion rate, DFS or OS.

Molecular characterization of metastatic pancreatic neuroendocrine tumors (PNETs) using whole-genome and transcriptome sequencing

Pancreatic neuroendocrine tumors (PNETs) are a genomically and clinically heterogeneous group of pancreatic neoplasms often diagnosed with distant metastases. Recurrent somatic mutations, chromosomal aberrations, and gene expression signatures in PNETs have been described, but the clinical significance of these molecular changes is still poorly understood, and the clinical outcomes of PNET patients remain highly variable. To help identify the molecular factors that contribute to PNET progression and metastasis, and as part of an ongoing clinical trial at the BC Cancer Agency (clinicaltrials.gov ID: NCT02155621), the genomic and transcriptomic profiles of liver metastases from five patients (four PNETs and one neuroendocrine carcinoma) were analyzed. In four of the five cases, we identified biallelic loss of MEN1 and DAXX as well as recurrent regions with loss of heterozygosity. Several novel findings were observed, including focal amplification of MYCN concomitant with loss of APC and TP53 in one sample with wild-type MEN1 and DAXX. Transcriptome analyses revealed up-regulation of MYCN target genes in this sample, confirming a MYCN-driven gene expression signature. We also identified a germline NTHL1 fusion event in one sample that resulted in a striking C>T mutation signature profile not previously reported in PNETs. These varying molecular alterations suggest different cellular pathways may contribute to PNET progression, consistent with the heterogeneous clinical nature of this disease. Furthermore, genomic profiles appeared to correlate well with treatment response, lending support to the role of prospective genotyping efforts to guide therapy in PNETs.

Outcomes and characteristics of patients receiving second-line therapy for advanced pancreatic cancer

435

Background: Recent trials have demonstrated improved outcomes in the 1st-line treatment of advanced pancreatic cancer (APC). However, there is limited randomized data to guide 2nd-line chemotherapy (CT) selection. We aimed to characterize predictors and outcomes of 2nd-line CT in patients (pts) with APC. Methods: We identified all pts with APC (locally advanced (LAPC) or metastatic (MPC)) who received ≥1 cycle of 1st-line CT between January 1, 2012 and December 31, 2015 across 6 centers in British Columbia, Canada. Baseline characteristics and survival outcomes were summarized. Results: Of 676 pts with APC (31% LAPC, 69% MPC) who received ≥1 cycle of CT, 164 (24%) received 2nd-line CT. These pts were younger (median 63.7 vs. 67.4 years; p= 0.01), had a lower ECOG (77% ECOG 0-1 vs. 51% ECOG ≥2; p< 0.001), and higher CA19-9 (median 1034 vs. 829; p= 0.01) compared to patients who did not receive 2nd-line CT. There were no differences in rates of 2nd-line CT between LAPC and MPC (28% vs. 23%; p= 0.18). On logistic regression, only 1st-line FOLFIRINOX (OR 5.90, p< 0.001) was associated with 2nd line CT. CT regimens are summarized by line (Table). Median duration of 2nd-line CT was 3 cycles (range 1-30). Median overall survival (mOS) from diagnosis of patients with 2nd-line CT was 16 months. mOS from 2nd-line CT was longer with 2nd-line gemcitabine/nab-paclitaxel than fluoropyrimidine or gemcitabine (7.9 vs. 5.1 vs. 4.3 months; p= 0.008). On multivariate analysis, longer OS from 2nd-line CT was associated with gemcitabine/nab-paclitaxel (vs. single agent CT), lower ECOG, LAPC (vs MPC), and lower CA 19-9 (HRs 0.49, 0.67, 0.58, 0.38, respectively). Conclusions: In this population-based cohort, pts treated with 2nd line CT were younger, have better ECOG, similar rates of LAPC vs. MPC, and achieved a median OS of 16 months. 1st-line FOLFIRINOX was the strongest predictor of 2nd-line CT. Gemcitabine/nab-paclitaxel was associated with superior 2nd line OS compared to gemcitabine/fluoropyrimidine. [Table: see text]

Real-World Effect of Maintenance and Intermittent Chemotherapy on Survival in Metastatic Colorectal Cancer

BACKGROUND

With improved survival and longer duration of treatment, clinicians managing metastatic colorectal cancer (mCRC) increasingly consider intermittent (IC) or maintenance chemotherapy (MC), but the effect of these treatment modifications on real-world outcomes is unclear.

PATIENTS AND METHODS

Using a population-based cohort of mCRC patients who received combination chemotherapy, we aimed to describe the use of IC/MC and their effect on overall survival (OS).

RESULTS

Among 617 patients, 120 (19%) had periods of IC, 67 (11%) had periods of MC, and 53 (9%) had periods of both. Most (85.5%) modifications occurred in the first-line setting. The receipt of IC (median OS [mOS], 37 vs. 21 months; P < .0001) or MC (mOS, 36 vs. 24 months; P = .0015) was associated with improved mOS compared with continuous combination therapy. In multivariate analysis adjusting for age, sex, and regimen used at the time of treatment modification, IC (hazard ratio [HR], 0.52; 95% confidence interval [CI], 0.42-0.65; P < .0001), MC (HR, 0.71; 95% CI, 0.58-0.88; P = .002), and the combination (HR, 0.45; 95% CI, 0.33-0.63; P < .0001) were all associated with improved mOS. Among patients receiving MC, individuals with (HR, 0.69; 95% CI, 0.53-0.90; P = .005) and without (HR, 0.74; 95% CI, 0.55-1.00; P = .048) re-escalation to their original cytotoxic regimen had improved mOS compared with continuous therapy. The use of IC was associated with an improved OS compared with MC (HR, 0.65; 95% CI, 0.47-0.90; P = .009).

CONCLUSION

In patients with mCRC, IC and MC are reasonable options to maintain quality of life and do not appear to negatively affect OS in carefully selected patients.

Inactivation of the Kinase Domain of CDK10 Prevents Tumor Growth in a Preclinical Model of Colorectal Cancer, and Is Accompanied by Downregulation of Bcl-2

Cyclin-dependent kinase 10 (CDK10), a CDC2-related kinase, is highly expressed in colorectal cancer. Its role in the pathogenesis of colorectal cancer is unknown. This study examines the function of CDK10 in colorectal cancer, and demonstrates its role in suppressing apoptosis and in promoting tumor growth in vitro and in vivo Modulation of CDK10 expression in colorectal cancer cell lines demonstrates that CDK10 promotes cell growth, reduces chemosensitivity and inhibits apoptosis by upregulating the expression of Bcl-2. This effect appears to depend on its kinase activity, as kinase-defective mutant colorectal cancer cell lines have an exaggerated apoptotic response and reduced proliferative capacity. In vivo, inhibiting CDK10 in colorectal cancer following intratumoral injections of lentivirus-mediated CDK10 siRNA in a patient-derived xenograft mouse model demonstrated its efficacy in suppressing tumor growth. Furthermore, using a tissue microarray of human colorectal cancer tissues, the potential for CDK10 to be a prognostic biomarker in colorectal cancer was explored. In tumors of individuals with colorectal cancer, high expression of CDK10 correlates with earlier relapse and shorter overall survival. The findings of this study indicate that CDK10 plays a role in the pathogenesis in colorectal cancer and may be a potential therapeutic target for treatment. Mol Cancer Ther; 16(10); 2292-303. ©2017 AACR.

Impact of Duration of Neoadjuvant Radiation on Rectal Cancer Survival: A Real World Multi-center Retrospective Cohort Study

BACKGROUND

The utility of neoadjuvant radiotherapy (nRT) for the treatment of stage II and III rectal cancer is well-established. However, the optimal duration of nRT in this setting remains controversial. Using a population-based cohort of patients with stage II and III rectal cancer (RC) treated with curative intent, our aims were to (1) examine the patterns of nRT use and (2) explore the relationship between different nRT schedules and survival in the real-world setting.

METHODS

This is a multi-center retrospective cohort study based on population-based data from 5 regional comprehensive cancer centers in British Columbia, Canada. We analyzed patients diagnosed with clinical stage II or III RC from 2006 to 2010 and treated with either short-course (SC) or long-course (LC) nRT prior to curative intent surgery. Logistic regression models were constructed to determine the factors associated with the course of nRT delivered to patients. Kaplan-Meier methods and Cox regression that accounted for known prognostic factors were used to evaluate the relationship between nRT schedule and overall (OS), disease-free (DFS), local recurrence-free (LRFS), and distant recurrence-free survival (DRFS).

RESULTS

We identified 427 patients: the median age was 65 years (range, 31 to 94 years), 67% were men, 87% had T3 or T4 tumors, and 74% had N1 or N2 disease. Among them, 241 (56%) received SC and 186 (44%) received LC. Adjusting for confounders, patients with N1 or N2 disease were more likely to undergo LC (odds ratio [OR], 5.08; 95% confidence interval [CI], 2.51-11.22; P < .0001 and OR, 8.35; 95% CI, 3.35-22.39; P < .0001, respectively), whereas older age patients were less likely to receive LC (OR, 0.95; 95% CI, 0.94-0.98; P < .0001). In Kaplan-Meier analysis, there were no significant differences observed in OS, DFS, LRFS, and DRFS between SC and LC. Likewise, multivariate analyses demonstrated that OS (hazard ratio [HR], 0.91; 95% CI, 0.61-1.37; P = .66), DFS (HR, 1.06; 95% CI, 0.68-1.64; P = .80), LRFS (HR, 0.79; 95% CI, 0.39-1.57; P = .50) and DRFS (HR, 0.99; 95% CI, 0.60-1.61; P = .95) were similar regardless of nRT schedules. Additional baseline clinical and tumor characteristics did not influence outcomes (all P > .05).

CONCLUSION

Appropriate preoperative selection of SC versus LC nRT for locally advanced RC based on patient and tumor characteristics was not associated with differences in survival outcomes in the real-world setting.

Temporal trends in the intensity and duration of oncologic care among colorectal cancer (CRC) patients (pts)

6552

Background: Substantial advances in therapy of CRC pts occurred between 2000 and 2012 contributing to a significant increase in overall survival. The objective of this study is to quantify the change in treatment (tx) intensity as measured by clinic and tx visits at a network of medical and radiation oncology clinics. Methods: Electronic scheduling records of stage I-IV CRC patients referred between 2000-2012 to the six oncology centers comprising the British Columbia Cancer Agency were reviewed and stratified by tx phases: I and II (adjuvant first 6 months, continued), III and IV (palliative first 6 months, continued), and V (last 6 months of life). Clinic Visit Intensity (CVI), Chemo Tx Intensity (CTI), number of chemo agents and number of cycles (CC), Radiotherapy (Rx) courses (RC) and fractions (RF) were measured, and trends by referral year were modelled using zero inflated negative binomial regression. Mean duration of visit for chemo tx (CHD) and clinic visits (CVD) were modelled using linear regression. Sex, age at diagnosis, stage, income, and community size were included in models if terms were significant. Results: 15,157 pts were included across 10 cohorts. CTI and CC increased significantly in tx phases II-V with later year of referral, while phase I results were stable or decreased, likely due to the substitution of oral for intravenous regimens. Rx increased only in advanced phases. Mean duration of scheduled time showed significant increases. Conclusions: CRC pts referred in 2012 vs 2000 receive significantly greater intensity and duration of care in tx phases II-V. Results have significant implications for resource allocation and the patient experience. [Table: see text]

The CCTG CO.26 trial: A phase II randomized study of durvalumab plustremelimumab and best supportive care (BSC) vs BSC alone in patients with advanced colorectal carcinoma (CRC) refractory to standard therapies

TPS3621

Background: Durvalumab (D) is a human monoclonal antibody (mAb) that inhibits binding of programmed cell death ligand 1 (PD-L1) to its receptor (PD-1) thereby preventing reduction in the number and efficacy of activated T-cells. Tremelimumab is a mAb directed against the cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) thereby resulting in enhanced T-cell activation and anti-tumour activity. Monotherapy with the anti-PD-1 agent pembrolizumab has demonstrated significant activity in CRC pts with tumours demonstrating microsatellite instability (MSI-H). Inhibiting PD-1/PD-L1 alone is likely of limited benefit in advanced CRC as only 5% of pts are MSI-H. Targeting both PD-L1 and CTLA-4 may have additive or synergistic activity as the mechanisms of action of CTLA-4 and PD-L1 inhibition are non-redundant. This study is designed to evaluate whether combining PD-L1 and CTLA-4 inhibition will lead to improved patient survival vs BSC alone in advanced CRC, regardless of MSI status. Methods: This randomized phase II study (ClinicalTrials.gov NCT02870920) will assess the efficacy and safety of D+T vs BSC in pts with metastatic or advanced, unresectable, refractory CRC (n = 180). Pts have failed standard chemotherapy based regimens containing a fluoropyrimidine, irinotecan and oxaliplatin (and an EGFR inhibitor, if Ras wild type) and no other therapeutic options. Pts are randomized in a 2:1 ratio to receive D (1500 mg) D1 q 28 days and T (75 mg) D1 for first 4 cycles. Treatment will continue until disease progression, death, intolerable toxicity, or patient/investigator decision to stop. Primary endpoint is overall survival; secondary endpoints include progression free survival, safety, overall response rate and quality of life. Analysis will be according to randomized group stratified by ECOG PS (0 vs 1) and site of tumour (right vs transverse vs left vs rectum). In addition, blood, plasma, and archival tissue will be collected and assessed for potential prognostic and predictive biomarkers, including tumour MSI status. As of February 1 2017, 20 pts have been randomized and recruitment is ongoing. Clinical trial information: NCT02870920.

Differences in systemic and surgical therapy between right (R) and left (L) sided metastatic colorectal cancer (mCRC)

3602

Background: Patients (pts) with L sided primary tumors and mCRC have a significantly longer overall survival (mOS) than R sided tumors. Reasons for this remain unclear. The objective of this study was to compare systemic and surgical therapy received by tumor side and correlate this with mOS. Methods: Sequential pts with mCRC referred to the British Columbia Cancer Agency in 4 treatment eras were included. Pts with unresected primary tumors were excluded to ensure accurate ascertainment of tumor location. Receipt of systemic therapy includes Òall 3 drugsÓ (irinotecan, oxaliplatin, fluouracil), bevacizumab and epidermal growth factor receptor inhibitors (EGFRi). Cox-regression survival analysis for sidedness was performed controlling for age, sex, tumor grade, lymphovascular/perineural invasion, nodes removed and metastatectomy. Results: Among 3242 pts, a progressive improvement in mOS is documented in both L and R sided tumors since 1995. L and R tumors received Òall 3 drugsÓ, bevacizumab and EGFRi therapy with similar frequency which plateaued after the introduction of EGFRiÕs in 2009. Patients with L sided tumors were significantly more likely to have a hepatic or pulmonary resection. In Cox regression analysis, the mOS difference between L and R sided tumors was more pronounced in more recent eras. Conclusions: Patients with R sided tumors receive similar systemic therapy compared to L sided tumors, but are significantly less likely to undergo resection of distant disease. Resection of distant metastases may be an important consideration to understand the survival differences between R vs L mCRC. [Table: see text]

Cost-effectiveness of surveillance after curative resection (CR) of metastatic colorectal cancer (CRC)

526

Background: Surveillance after CR of stage I-III CRC is recommended by most major oncology organizations to detect asymptomatic recurrences. Such recurrences are more likely to benefit from early interventions such as CR of metastases. Only the NCCN recommends a surveillance schedule after CR of metastases that includes CEA testing, imaging and clinical evaluation every 3-6 months for 2 years, and then every 6-12 months in years 3 to 5. Periodic endoscopy is also recommended. It is unclear if there is cost-effective surveillance strategy for metastatic CRC after CR. Methods: A Monte Carlo micro-simulation model was constructed using a 1-month cycle length and 10 year time horizon. Surveillance strategies were compared based on NCCN guidelines, with testing every 3 months (3M) or 6 months (6M), as well as two alternate strategies of testing every 12 months (12M) or no surveillance (None) for 5 years. Recurrence, repeat CR rates, and survival outcomes were modeled from population-based outcomes of 257 patients who had CR of mCRC in British Columbia, Canada. Asymptomatic recurrences were more likely to undergo CR, compared to symptomatic ones. Additional costs, utilities, and probabilities were derived from the literature. Costs are in 2015 CAD and utilities in Quality-adjusted life years (QALY), and both discounted at 3% and half-cycle corrected. Analyses were performed using TreeAge Pro with 1000 trials and 1000 distribution samplings. Results: The incremental cost-effectiveness ratio (ICER) and net monetary benefit (NMB) are listed in the Table. Increasing the frequency of surveillance tests does lead to modest gains in QALY, however, the cost of surveillance and subsequent treatment is high. Using a willingness to pay threshold of 150 000 CAD, the 6M strategy would be favored. Conclusions: In the Canadian context, the optimal surveillance strategy after CR of mCRC matches with the 6M strategy recommended by the NCCN. An additional Canadian data set will be used to externally validate the model outcomes. [Table: see text]