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Supplementary Data: List of TRIO investigators, Supplementary Materials and Methods, Supplementary Results, Supplementary Discussion, Supplementary References, Supplementary Tables, and Supplementary Figures.

Supplemental Table 3

Supplemental Figure S1. Mean pharmacokinetic profiles for single agent talazoparib (BMN673 in phase I clinical trial PRP-001) versus combination therapy.

Supplemental Table 2

Supplemental Table 1

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This selection from the NCCN Guidelines for Rectal Cancer focuses on management of malignant polyps and resectable nonmetastatic rectal cancer because important updates have been made to these guidelines. These recent updates include redrawing the algorithms for stage II and III disease to reflect new data supporting the increasingly prominent role of total neoadjuvant therapy, expanded recommendations for short-course radiation therapy techniques, and new recommendations for a “watch-and-wait” nonoperative management technique for patients with cancer that shows a complete response to neoadjuvant therapy. The complete version of the NCCN Guidelines for Rectal Cancer, available online at NCCN.org, covers additional topics including risk assessment, pathology and staging, management of metastatic disease, posttreatment surveillance, treatment of recurrent disease, and survivorship.

PURPOSE SEQUOIA compared efficacy and safety of adding pegilodecakin (PEG), a pegylated recombinant human interleukin (IL)-10, with folinic acid, fluorouracil, and oxaliplatin (FOLFOX) in patients following progression on first-line gemcitabine-containing therapy with metastatic pancreatic ductal adenocarcinoma (PDAC). PATIENTS AND METHODS SEQUOIA, a randomized, global phase III study, compared FOLFOX with PEG + FOLFOX as second line in gemcitabine-refractory PDAC. Patients were randomly assigned 1:1 (PEG + FOLFOX:FOLFOX) and stratified by prior gemcitabine and region. Eligible patients had only one prior gemcitabine-containing treatment. Primary end point was overall survival (OS). Secondary end points included progression-free survival (PFS), response evaluation per Response Evaluation Criteria in Solid Tumor (RECIST) 1.1, and safety. Exploratory analyses included biomarkers related to immune activation. RESULTS Between March 1, 2017, and September 9, 2019, 567 patients were randomly assigned PEG + FOLFOX (n = 283) or FOLFOX (n = 284). Most (94.7%) patients received prior gemcitabine plus nab paclitaxel. OS was similar comparing PEG + FOLFOX versus FOLFOX (median: 5.8 v 6.3 months; hazard ratio = 1.045; 95% CI, 0.863 to 1.265). Also, PFS (median 2.1 v 2.1 months; hazard ratio = 0.981; 95% CI, 0.808 to 1.190) and objective response rate (4.6% v 5.6%) were similar between the treatment arms. Most common (≥ 35%) treatment-emergent adverse events in PEG + FOLFOX versus FOLFOX were thrombocytopenia (55% v 20%), anemia (40% v 16%), fatigue (61% v 45%), neutropenia (39% v 28%), abdominal pain (37% v 29%), nausea (45% v 41%), neuropathy (37% v 38%), and decreased appetite (35% v 31%). Exploratory analyses revealed increases in total IL-18, interferon (IFN)-γ, and granzyme B and decreases in transforming growth factor (TGF)-β with the addition of PEG. CONCLUSION PEG added to FOLFOX did not improve efficacy in advanced gemcitabine-refractory PDAC. Safety findings were consistent as previously observed from PEG with chemotherapy; toxicity was manageable and tolerable. Exploratory pharmacodynamic results were consistent with immunostimulatory signals of the IL-10R pathway.

This selection from the NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines) for Colon Cancer focuses on systemic therapy options for the treatment of metastatic colorectal cancer (mCRC), because important updates have recently been made to this section. These updates include recommendations for first-line use of checkpoint inhibitors for mCRC, that is deficient mismatch repair/microsatellite instability-high, recommendations related to the use of biosimilars, and expanded recommendations for biomarker testing. The systemic therapy recommendations now include targeted therapy options for patients with mCRC that is HER2-amplified, or BRAF V600E mutation–positive. Treatment and management of nonmetastatic or resectable/ablatable metastatic disease are discussed in the complete version of the NCCN Guidelines for Colon Cancer available at NCCN.org. Additional topics covered in the complete version include risk assessment, staging, pathology, posttreatment surveillance, and survivorship.

Background Treatment options for pancreatic ductal adenocarcinoma (PDAC) are limited and checkpoint blockade inhibitors have been disappointing in this disease. Pegilodecakin has demonstrated single agent anti-tumor activity in immune-sensitive tumors. Phase 1 and preclinical data indicate synergy of pegilodecakin with 5-FU and platins. We assessed the safety and activity of pegilodecakin+FOLFOX in patients with PDAC. Methods IVY (NCT02009449) was an open-label phase 1b trial in the United States. Here we report on all enrolled patients from cohort C. Heavily pretreated patients were treated with pegilodecakin (self-administered subcutaneously daily at 2.5, 5, or 10μg/kg) + 5-flurouracil/leucovorin/oxaliplatin (FOLFOX), dosed per manufacturers prescribing information, until tumor progression. Eligible patients had measurable disease per immune-related response criteria (irRC), were ≥ 18years of age, and had ECOG performance status of 0 or 1. Patients were evaluated for primary(safety) and secondary (tumor response per irRC) endpoints. Results From 5 August 2014-12 July 2016, 39 patients enrolled in cohort C. All patients were evaluable for safety. In this advanced population, regimen had manageable toxicities with no immune-related adverse events (irAEs) greater than grade 1. The most common grade 3/4/5 TEAEs were thrombocytopenia (21[53.8%] of 39) and anemia (17[43.6%] of 39). In evaluable PDAC patients, the best overall response of pegilodecakin+FOLFOX was 3(14%) with CRs in 2(9%) patients. Conclusions Pegilodecakin+FOLFOX had an acceptable tolerability profile in PDAC, with no substantial irAEs seen, and promising efficacy with the combination yielding a 2-year OS of 24% (95% CI 10-42). These data led to the phase 3 study with pegilodecakin+FOLFOX as second-line therapy of PDAC (SEQUOIA).

Purpose: On the basis of preclinical data, we hypothesized that low doses of chemotherapy (10% of therapeutic doses) with full dose of a PARP inhibitor could have improved efficacy and tolerability. Patients and Methods: In this phase I dose-escalation study, patients with BRCA-normal advanced malignancies were assigned to either talazoparib/temozolomide or talazoparib/irinotecan. Talazoparib was dose-escalated from 500 mcg to 1 mg daily before dose escalation of temozolomide/irinotecan. The starting dose of temozolomide was 25 mg/m2/day orally on days 1 to 5 and irinotecan was 25 mg/m2/day intravenously on days 1 and 15. The primary objectives of this trial were safety and tolerability, dose-limiting toxicities (DLT), and maximum tolerated dose (MTD). Results: Of 40 patients enrolled, 18 (mean: 7 prior therapies) were enrolled in talazoparib + temozolomide and 22 in talazoparib + irinotecan. DLTs were hematologic in both arms, but all hematologic adverse events resolved with either treatment interruption and/or dose reductions of talazoparib. The MTDs were talazoparib 1 mg + temozolomide 37.5 mg/m2 and talazoparib 1 mg + irinotecan 37.5 mg/m2. There were four partial responses in the talazoparib + temozolomide arm and five in the talazoparib + irinotecan arm for a response rate of 23% (9/40). The pharmacokinetic profiles of talazoparib + temozolomide/irinotecan were similar to that of talazoparib monotherapy. Responses were seen independent of homologous recombination (HR) status and HR deficiency score. Conclusions: These results show that talazoparib with low-dose temozolomide or irinotecan is reasonably well tolerated and demonstrates clinical activity in a wide range of cancers. Randomized trials of talazoparib with or without low-dose chemotherapy are ongoing in small cell lung cancer and ovarian cancer.

Background: BOLD-100 is a first-in-class ruthenium-based anticancer agent in Phase 1b/2a clinical development for the treatment of advanced gastrointestinal (GI) cancers in combination with FOLFOX. BOLD-100 demonstrated synergy in established preclinical models in combination with various anticancer therapies, particularly in resistant cell lines. In the first interim analysis of the phase 1b dose-escalation component of the clinical trial, BOLD-100 plus FOLFOX was well-tolerated in patients (pts) with advanced GI solid cancers. Methods: This is a prospective, Phase 1b dose-escalation (Part A) and Phase 2a dose-expansion (Part B) study of BOLD-100 in combination with FOLFOX for colorectal (CRC), pancreatic (PDAC), gastric (GC) and biliary tract (BTC) cancers. Pts receive BOLD-100 with FOLFOX on day 1 of each 14-day cycle. In Part A, pts were enrolled in a 3+3 design to determine the combination recommended Phase 2 dose (RP2D), with BOLD-100 dose-escalation (420, 500 and 625 mg/m2). Part B comprises 4 cohorts treated at the RP2D of 625 mg/m2 until progressive disease or unacceptable toxicity. The primary objective of Part B is to evaluate the efficacy of BOLD-100 in three clinical endpoints (PFS, OS, and ORR). Bayesian modelling is used to continually reassess these endpoints; the posterior probability of superiority to a historical landmark for each endpoint. Results: As of 31 Dec 2022, 17 pts with advanced metastatic colorectal cancer median age 62 years were treated. Pts received a median of 4 prior systemic therapies, 14 had received prior FOLFOX and 16 (94%) were enrolled with stage IV disease. Median number of cycles completed was 7 (range 1-12). Median PFS was 4.7 [2.9,8.6] months, median OS 9.8 [5.2,22] months, and ORR 13% [3,36] compared to the historical benchmark of 2.0 months, 7.1 months, and 1.6% respectively for similar patients treated with approved standard of care. Two pts achieved a partial response and 11 pts had stable disease for an overall disease control rate of 87% (13/15 [64%,97%]). This compares favorably to the historical control 44%. 16 pts reported 1 or more treatment-emergent adverse events (AEs), most commonly neutrophil count decreased (n=9, 52.9%), fatigue (n=6, 35.3%), pyrexia (n=4, 23.5%), platelet count decreased (n=4, 23.5%) and decreased appetite (n=4, 23.5%). Most of the AEs were grade (G) 1-2. 12 G3 AEs were observed (mostly neutrophil count decreased [8]). Conclusion: BOLD-100 plus FOLFOX is an active and well-tolerated treatment regimen in the heavily pre-treated metastatic CRC trial population. There were no new safety signals. PK and PD data are forthcoming. The preliminary mPFS, mOS, ORR and DCR data in this interim analysis demonstrate significant improvement over the currently available approved therapies. Citation Format: Jennifer Spratlin, Grainne O'Kane, Do-Youn Oh, Sun Young Rha, Elaine McWhirter, Elena Elimova, Petr Kavan, Moon Ki Choi, Dae Won Kim, Rachel Goodwin, J Randolph Hecht, Seung Tae Kim, Dong-Hoe Koo, Khalif Halani, E Russell McAllister, Michelle Jones, Malcolm Snow, Yasmin Lemmerick, Gonzalo Spera, Jim Pankovich. BOLD-100-001 (TRIO039): a phase 1b/2a dose-escalation study of BOLD-100 in combination with FOLFOX chemotherapy in patients with pre-treated advanced colorectal cancer: interim efficacy, safety and tolerability analysis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 2 (Clinical Trials and Late-Breaking Research); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(8_Suppl):Abstract nr CT149.

209 Background: Metastatic colorectal (CRC), pancreatic (PANC), and gastroesophageal cancers are the leading causes of GI cancer–related mortality (5-y survival: 15%, 3%, and 5%-6%, respectively) (ACS 2022). HLA LOH is a recurrent mechanism of immune escape observed in 15%-20% of GI cancers (Hecht R., ASCO GI 2022). The Tmod platform is a logic-gated chimeric antigen receptor (CAR) T-cell modular system, comprising a carcinoembryonic antigen (CEA)- or mesothelin (MSLN)-targeting CAR activator and a separate HLA-A*02-targeting blocker receptor. Both in vitro/in vivo, Tmod CAR T therapy kills cells with HLA-A*02 LOH (tumor) without harming cells with retained HLA-A*02 expression (normal). However, HLA-A*02 LOH can only be therapeutically exploited if patients are identifiable through a feasible and timely clinical workflow. Methods: We established a biobanking protocol (BASECAMP-1, NCT04981119) to determine whether HLA-A*02 LOH patients can be prospectively identified. Patients with CRC, PANC, or non-small cell lung cancer (NSCLC), and a high risk for incurable relapse, were screened first using a standard HLA assay. Heterozygous HLA-A*02 positive tumor samples were then assessed for LOH using a bioinformatic algorithm applied via the Tempus xT platform. Results: As of Sep 1, 2022, 83 patients were consented at 4 institutions. HLA status was obtained from 70 patients and 28 were identified as HLA-A*02:01 heterozygous (40%; expected frequency based on USA NMDP data, 27.6%). LOH results were available for 16 patients; 4 LOH-positive patients were identified (25%, 2 PANC, 2 NSCLC). The LOH assay sensitivity declines below a tumor purity of 40% (Hecht R., ASCO GI 2022). Six patients had a tumor purity of 20% (all with PANC, a tumor known for high stromal content), limiting possible LOH detection. The impact of tumor purity on LOH sensitivity was highlighted in a patient with a low initial sample tumor purity (30%) that resulted in a 41% probability of HLA-A*02:01 LOH (below positive threshold). A second sample with a higher tumor purity (70%), obtained from formalin-fixed, paraffin-embedded sections, resulted in a 92% probability of HLA-A*02:01 LOH (positive). Conclusions: BASECAMP-1 prospective identification of HLA-A*02 LOH is feasible in the real-world setting. The frequencies of the HLA-A*02 allele and of HLA-A*02 LOH in this cohort mirrored expected population frequencies. LOH results can be obtained within a clinically feasible workflow and timeframe, although samples with a < 40% tumor purity have a reduced sensitivity for LOH detection, an issue recurrently observed in patients with PANC. The BASECAMP-1 strategy enables prospective identification of appropriate patients for future therapeutic clinical trials using Tmod CEA and MSLN logic-gated CAR T cells. Clinical trial information: NCT04981119 .

TPS267 Background: The prognosis of patients with mCRC is poor, with a 5-year survival rate of 14% (American Cancer Society 2020). Patients who have progressed after front-line chemotherapy have limited treatment options. Regorafenib or trifluridine-tipiracil are approved for patients in the third- or later-line setting, but survival benefit is limited. While immune checkpoint inhibitor (ICI) therapy is approved (nivolumab ± ipilimumab, and pembrolizumab) in patients with microsatellite instability-high (MSI-H) or mismatch repair deficient (dMMR) mCRC, the MSI-H phenotype is limited to ~5% of mCRC patients. In phase 1/2 trials, ICIs in combination with VEGFR2 multi-kinase inhibitors (MKIs) have demonstrated encouraging clinical activity in mCRC, including atezolizumab and durvalumab (ICIs) in combination with the MKI cabozantinib, with data suggesting a greater benefit in RAS wild-type (wt) vs mutant (mut) disease (Abrams TA, et al. ASCO GI 2022:Abs 121; Saeed A, et al. ASCO GI 2022:Abs 135). XL092 is a novel MKI, targeting MET, VEGFR2, and the TAM kinases AXL and MER; the relatively short half-life (~21 hours) of XL092 is favorable for once-daily (QD) dosing and dose modification to manage tolerability. STELLAR-303 is a phase 3 study evaluating the efficacy and safety of XL092 + atezolizumab versus regorafenib in patients with previously treated RASwt or RASmut mCRC. Methods: STELLAR-303 (XL092-303; NCT05425940) is a global, open-label, randomized phase 3 study. Eligible patients are ≥18 years old and have mCRC that is measurable per RECIST v1.1, are documented not to have MSI-H or dMMR disease, and have an ECOG performance status of 0–1 and adequate organ function. RAS and MSI/dMMR status must be determined by a tissue-based analysis. Patients must have progressed during/after or be intolerant to standard-of-care treatments for mCRC; prior regorafenib, trifluridine/tipiracil, or PD-L1/PD-1 ICIs are not allowed. Patients are randomized 1:1 to XL092 100 mg PO QD + atezolizumab 1200 mg IV Q3W or to regorafenib 160 mg PO QD (21 days of 28-day cycle); randomization is stratified by geographic region (Asia vs other), RAS status (wt vs mut), and liver metastases (yes/no). The study plans to enroll 600 patients (400 RASwt and 200 RASmut). The primary endpoint is overall survival in the RASwt population, with additional efficacy endpoints of progression-free survival, objective response rate, and duration of response per RECIST v1.1 by investigator; efficacy endpoints will also be assessed in the overall study population and in patients with RASmut mCRC. Additional endpoints will assess safety, quality of life, changes in biomarkers, pharmacokinetics, immunogenicity of atezolizumab, and healthcare utilization. Enrollment is ongoing. Clinical trial information: NCT05425940 .

Colorectal cancer (CRC) is associated with alterations of the fecal and tissue-associated microbiome. Preclinical models support a pathogenic role of the microbiome in CRC, including in promoting metastasis and modulating antitumor immune responses. To investigate whether the microbiome is associated with lymph node metastasis and T cell infiltration in human CRC, we performed 16S rRNA gene sequencing of feces, tumor core, tumor surface, and healthy adjacent tissue collected from 34 CRC patients undergoing surgery (28 fecal samples and 39 tissue samples). Tissue microbiome profiles—including increased Fusobacterium—were significantly associated with mesenteric lymph node (MLN) involvement. Fecal microbes were also associated with MLN involvement and accurately classified CRC patients into those with or without MLN involvement. Tumor T cell infiltration was assessed by immunohistochemical staining of CD3 and CD8 in tumor tissue sections. Tumor core microbiota, including members of the Blautia and Faecalibacterium genera, were significantly associated with tumor T cell infiltration. Abundance of specific fecal microbes including a member of the Roseburia genus predicted high vs. low total and cytotoxic T cell infiltration in random forests classifiers. These findings support a link between the microbiome and antitumor immune responses that may influence prognosis of locally advanced CRC.

Circulating tumor cell (CTC) clusters are present in cancer patients with severe metastasis, resulting in poor clinical outcomes. However, CTC clusters have not been studied as extensively as single CTCs, and the clinical utility of CTC clusters remains largely unknown. In this study, we aim sought to explore the feasibility of NanoVelcro Chips to simultaneously detect both single CTCs and CTC clusters with negligible perturbation to their intrinsic properties in neuroendocrine tumors (NETs). We discovered frequent CTC clusters in patients with advanced NETs and examined their potential roles, together with single NET CTCs, as novel biomarkers of patient response following peptide receptor radionuclide therapy (PRRT). We observed dynamic changes in both total NET CTCs and NET CTC cluster counts in NET patients undergoing PRRT which correlated with clinical outcome. These preliminary findings suggest that CTC clusters, along with single CTCs, offer a potential non-invasive option to monitor the treatment response in NET patients undergoing PRRT.

Impact of geography on prognostic outcomes of 21,509 patients with metastatic colorectal cancer enrolled in clinical trials: an ARCAD database analysis\ud Show less\ud Jun Yin*, Shaheenah Dawood*, Romain Cohen, Jeff Meyers, John Zalcberg, Takayuki Yoshino, Matthew Seymour, Tim Maughan, Leonard Saltz, Eric Van Cutsem, Alan Venook, Hans-Joachim Schmoll, Richard Goldberg, Paulo Hoff, J. Randolph Hecht, Herbert Hurwitz, Cornelis Punt, Eduard Diaz Rubio, Miriam Koopman, Chiara Cremolini, Volker Heinemann, Christophe Tournigard, Carsten Bokemeyer, Charles Fuchs, Niall Tebbutt, John Souglakos, Jean-Yves Doulliard, Fairooz Kabbinavar, Benoist Chibaudel, Aimery de Gramont, Qian Shi, Axel Grothey, Richard AdamsFirst Published June 30, 2021 Research Article\ud https://doi.org/10.1177/17588359211020547\ud Article information \ud Article has an altmetric score of 7 Open AccessCreative Commons Attribution, Non Commercial 4.0 License\ud Article Information\ud Volume: 13\ud Article first published online: June 30, 2021; Issue published: January 1, 2021\ud Received: December 29, 2020; Accepted: May 05, 2021\ud Jun Yin*\ud Department of Health Sciences Research, Mayo Clinic, 200 First Street, SW Rochester, MN 55905, USA\ud Shaheenah Dawood*\ud Mediclinic City Hospital: North Wing, Dubai Health Care City, Dubai UAE\ud Romain Cohen\ud Department of Health Sciences Research, Mayo Clinic, Rochester, MN, USA\ud Jeff Meyers\ud Department of Health Sciences Research, Mayo Clinic, Rochester, MN, USA\ud John Zalcberg\ud School of Public Health and Preventative Medicine, Monash University, Melbourne, Australia\ud Takayuki Yoshino\ud Department of Gastrointestinal Oncology, National Cancer Center Hospital East, Chiba, Japan\ud Matthew Seymour\ud NIHR Clinical Research Network, Leeds, UK\ud Tim Maughan\ud CRUK/MRC Oxford Institute for Radiation Oncology, Oxford, UK\ud Leonard Saltz\ud Memory Sloan Kettering Cancer Center, New York, NY, USA\ud Eric Van Cutsem\ud Digestive Oncology, University Hospitals Gasthuisberg Leuven and KU Leuven, Leuven, Belgium\ud Alan Venook\ud Department of Medicine, The University of California San Francisco, San Francisco, CA, USA\ud Hans-Joachim Schmoll\ud Klinik fur Innere Med IV, University Clinic Halle, Saale, Germany\ud Richard Goldberg\ud Department of Oncology, West Virginia University, Morgantown, WV, USA\ud Paulo Hoff\ud Centro de Oncologia de Brasilia do Sirio Libanes: Unidade Lago Sul, Siro Libanes, Brazil\ud J. Randolph Hecht\ud Ronald Reagan UCLA Medical Center, UCLS Medical Center, Santa Monica, CA, USA\ud Herbert Hurwitz\ud Duke Cancer Institute, Duke University, Durham, NC, USA\ud Cornelis Punt\ud Department of Medical Oncology, University of Amsterdam, Amsterdam, The Netherlands\ud Eduard Diaz Rubio\ud Department Oncology, Hospital Clínico San Carlos, Madrid, Spain\ud Miriam Koopman\ud Department of Medical Oncology, University Medical Center Utrecht, University of Utrecht, Utrecht, The Netherlands\ud Chiara Cremolini\ud Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Pisa, Italy\ud Volker Heinemann\ud Department of Medical Oncology and Comprehensive Cancer Center, University of Munich, Munich, Germany\ud Christophe Tournigard\ud Hopital Henri Mondor, Creteil, France\ud Carsten Bokemeyer\ud Department of Oncology, Hematology and Bone Marrow Transplantation with Section of Pneumology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany\ud Charles Fuchs\ud Director of Yale Cancer Center, Boston, MA, USA\ud Niall Tebbutt\ud Sydney Medical School, University of Sydney, Sydney, Australia\ud John Souglakos\ud University of Crete, Heraklion, Greece\ud Jean-Yves Doulliard\ud University of Nantes Medical School, Nantes, France\ud Fairooz Kabbinavar\ud UCLA Medical Center, Santa Monica, CA, USA\ud Benoist Chibaudel\ud Department of Medical Oncology, Franco-British Institute, Levallois-Perret, France\ud Aimery de Gramont\ud Department of Medical Oncology, Franco-British Institute, Levallois-Perret, France\ud Qian Shi\ud Department of Health Sciences Research, Mayo Clinic, Rochester, MN, USA\ud Axel Grothey\ud West Cancer Center, Germantown, TN, USA\ud Richard Adams\ud Cardiff University and Velindre Cancer Center, Cardiff, UK\ud \ud Corresponding Author:\ud \ud yin.jun@mayo.edu\ud *Co-first authors.\ud \ud https://creativecommons.org/licenses/by-nc/4.0/This article is distributed under the terms of the Creative Commons Attribution-NonCommercial 4.0 License (https://creativecommons.org/licenses/by-nc/4.0/) which permits non-commercial use, reproduction and distribution of the work without further permission provided the original work is attributed as specified on the SAGE and Open Access page (https://us.sagepub.com/en-us/nam/open-access-at-sage).\ud Abstract\ud Background:\ud Benchmarking international cancer survival differences is necessary to evaluate and improve healthcare systems. Our aim was to assess the potential regional differences in outcomes among patients with metastatic colorectal cancer (mCRC) participating in international randomized clinical trials (RCTs).\ud \ud Design:\ud Countries were grouped into 11 regions according to the World Health Organization and the EUROCARE model. Meta-analyses based on individual patient data were used to synthesize data across studies and regions and to conduct comparisons for outcomes in a two-stage random-effects model after adjusting for age, sex, performance status, and time period. We used mCRC patients enrolled in the first-line RCTs from the ARCAD database, which provided enrolling country information. There were 21,509 patients in 27 RCTs included across the 11 regions.\ud \ud Results:\ud Main outcomes were overall survival (OS) and progression-free survival (PFS). Compared with other regions, patients from the United Kingdom (UK) and Ireland were proportionaly over-represented, older, with higher performance status, more frequently male, and more commonly not treated with biological therapies. Cohorts from central Europe and the United States (USA) had significantly longer OS compared with those from UK and Ireland (p = 0.0034 and p

Purpose: Most gastrointestinal stromal tumors (GIST) are driven by KIT/PDGFRa mutations. Tyrosine kinase inhibitor benefit is progressively less after imatinib failure. This phase II trial analyzed the efficacy of nivolumab (N) or nivolumab + ipilimumab (N + I) in patients with refractory GIST. Patients and Methods: Patients with advanced/metastatic GIST refractory to at least imatinib were randomized 1:1 in a noncomparative, parallel group, unblinded phase II trial of N (240 mg every 2 weeks) or N + I (240 mg every 2 weeks + 1 mg/kg every 6 weeks). The primary endpoint was the objective response rate of N alone or N+I by RECIST 1.1 in the intent-to-treat population. Results: A total of 36 patients with a median of 3 (1–6) prior lines of therapies were enrolled. Ten of 19 (52.6%) patients had stable disease (SD) for a clinical benefit rate (CBR) of 52.6% in the N arm and the median progression-free survival (PFS) was 11.7 weeks [95% confidence interval (CI), 7.0–17.4]. In the N+I arm, 1 of 16 (6.7%) patients had a complete response (CR) and 4/16 (25.0%) had SD for a CBR of 31.3% and a median PFS of 8.3 weeks (95% CI, 5.6–22.2). The 4- and 6-month PFS were 42.1% and 26.3%, respectively for N, and 31.3% and 18.8%, respectively for N+I. The most common adverse events (AE) attributed to N and N+I were fatigue: 13.9% and 22.2%, respectively. There were nine total attributable grade 3–4 AEs. Conclusions: The primary endpoint of response rate > 15% was not observed for N or N + I. In a heavily pretreated GIST population, responses and long-term disease control with both N and N+I were observed. No new safety signals have been observed.

TPS4181 Background: The mainstay of treatment (TX) for pts with advanced or mPDAC consists of CT, with FOLFIRINOX and gemcitabine (gem)/nab-paclitaxel currently representing the front-line standards of care. TX is generally continued until either dis progression (progr) or cumulative toxicity, with pts often reaching a plateau in response after 4-6 mos. For those who have achieved dis control (stable dis or better) on front-line CT, a maint TX strategy that can effectively delay dis progr while preserving quality of life with minimal cumulative toxicity is highly desirable. However, aside from PARP inhibition in the subset of PDAC pts with gBRCA mutated dis, there is no current standard of care in this maint setting. Ival is a pan-HDAC (histone deacetylation) inhibitor that increases histone acetylation (HA), suppresses PDAC cell proliferation, and promotes apoptosis in PDAC cell lines in a dose-dependent manner. It has demonstrated synergy with 5-FU in cholangiocarcinoma cell lines and shows promising antitumor activity when combined with cap in syngeneic PDAC mouse models. On these bases, we are conducting a ph1b/randomized ph2 trial of ival plus cap vs cap alone in the maint setting for pts with mPDAC who have not progressed on front-line FOLFIRINOX. Methods: Key eligibility criteria include pts with mPDAC; no evidence of dis progr following at least 16 wks of front-line FOLFIRINOX at full or modified doses; ECOG PS 0-1; and no known gBRCA1/2 mutation. The study includes an initial dose-esc ph1b evaluating 3 dose levels of ival, (60, 125, and 250mg/m2 iv weekly on days 1 and 8) in combination (comb) with cap (1000mg/m2 po BID on days 1-14) of a 21-day cycle, using a standard 3 + 3 dose-esc design. Of note, ival 250 mg/m2 represents the RP2D identified in prior clinical studies of this agent both as monotherapy in solid tumors and in comb with gem/erlotinib in advanced PDAC pts. In the ph2 portion, pts will be randomized 1:1 to receive either ival plus cap or cap alone, in 21-day cycles, until dis progr, with tumor assessments occurring at 6-wk intervals. Blood will be collected at pre-specified serial timepoints for pharmacodynamic assessments, including HA of PBMCs. Primary endpoint for ph2 is investigator-adjudicated PFS. The primary analysis will compare PFS distributions in the ival/cap and cap alone arms using a one-sided log rank test with an alpha = 0.10. The assumed true 6-mo PFS rates are 35% (cap), based on historic data, and 60% (ival/cap), which corresponds to an HR of 0.487. Assuming an accrual duration of 18 mos and a dropout/lost to follow-up rate of 10%, the estimated total number of pts in the randomized ph2 portion is 52 (26 per arm). Enrollment is expected to being in spring 2022 across 25 U.S. sites.

TPS3635 Background: Treatment options for most patients with metastatic colorectal cancer (mCRC) are largely limited to cytotoxic chemotherapy, with little advancement in the last decade. Encouragingly, a small subset of patients deficient in mismatch repair (dMMR/MSI-hi) benefit from checkpoint inhibitors (CPI) whereas those proficient in mismatch repair (pMMR/MSS) do not. The absence of clinical benefit in patients with pMMR/MSS mCRC may relate to a lack of neoantigen-specific T cells and immune infiltration. An individualized neoantigen vaccine that induces CD8 T cells capable of tumor lysis has the potential to expand the number of patients with mCRC who may benefit from immunotherapy. Data from a Phase 1/2 study evaluating neoantigen vaccines in combination with CPIs in patients with previously treated mCRC demonstrated a 44% molecular response (MR) rate (≥50% decrease in ctDNA relative to baseline) in 4/9 patients; this correlated with improvement in OS relative to those without a MR. To further investigate neoantigen vaccines in earlier lines of treatment, a Phase 2/3 study in the1L maintenance setting in mCRC was initiated. Methods: GO-010 is a Phase 2/3, randomized, open-label, multi-center study evaluating the efficacy and safety of 2 neoantigen-containing vectors (GRT-C901-adenoviral vector plus GRT-R902-self-amplifying mRNA vector) as prime/boost in combination with CPIs as an add-on to fluoropyrimidine/bevacizumab (bev) following 1L therapy with FOLFOX/bev in patients with mCRC. During Phase 2, up to 90 patients will be randomized 1:1 to the vaccine or control arm with a primary objective of assessing efficacy by MR. During Phase 3, up to 226 patients will be randomized with a primary objective of assessing PFS per iRECIST in a blinded, independent manner. There are two stages to the study. In the vaccine production stage, while patients receive FOLFOX/bev 1L therapy, neoantigen prediction is performed using a tumor biopsy and Gritstone’s EDGE™ neoantigen prediction model. For patients in the vaccine arm the top 20 predicted neoantigens are included in the vaccine vectors. After completing oxaliplatin, patients will enter the study treatment stage. Patients in the control arm will continue with maintenance therapy whereas patients in the vaccine arm will add the vaccine regimen to maintenance therapy. The vaccine regimen consists of GRT-C901/GRT-R902 as well as SC ipilimumab (30 mg) and IV atezolizumab (1680 mg). Over the first year of treatment, 6 vaccinations will occur. Ipilimumab will be administered SC with the first doses of GRT-C901 and GRT-R902. Atezolizumab will be administered every 4 weeks for up to 2 years. Study assessments include imaging, ctDNA, safety, immunogenicity and exploratory biomarker analysis. Clinical trial information: NCT05141721.

TPS2676 Background: Solid tumors comprise > 90% of cancers. Metastatic colorectal cancer, non-small cell lung cancer, and pancreatic cancer are among the leading causes of cancer-related mortality (5-year overall survival: 14%, 6%, and 3%, respectively) (ACS. 2021). Chimeric antigen receptor (CAR) T-cell therapy has demonstrated clinical efficacy in hematologic malignancies (Neelapu S. et al. N Engl J Med. 2017). Translating engineered T-cell therapies to solid tumors has proven to be challenging due to a lack of tumor-specific targets that can discriminate cancer cells from normal cells. Previous studies using carcinoembryonic antigen (CEA) T-cell receptors and mesothelin (MSLN) CARs resulted in dose-limiting on-target, off-tumor toxicities (Parkhurst M, et al. Mol Ther. 2011; Tanyi J. Cellicon Valley '21). To create a therapeutic safety window, Tmod CAR T-cell therapy utilizes dual-signaling receptors to create a robust NOT logic gate capable of killing tumor cells, while leaving healthy cells intact (Hamburger A, et al. Mol Immunol. 2020). The 2 receptors in Tmod CAR T-cell therapy comprise an activator that recognizes an antigen on the surface of tumor cells that may also be present on normal cells, such as CEA and MSLN, and a blocker that recognizes a second surface antigen from an allele lost only in tumor cells. The frequency of HLA LOH among advanced GI solid tumor cancers in the Tempus real-world dataset is 16.3% with a range of 15.6%-20.8% between colorectal, pancreatic, and gastroesophageal tumors (Hecht R. et al. ASCO-GI 2022. Abstract #190). As such, HLA LOH offers a definitive tumor versus normal discriminator target for CAR T-cell therapy. Different activator/blocker combinations can be engineered with the Tmod platform technology and may be applied to T cells and natural killer cells in autologous and allogeneic settings. BASECAMP-1 is a currently enrolling observational study with key objectives of 1) To identify patients with somatic HLA LOH eligible for Tmod CAR T-cell therapy, and 2) To obtain leukapheresis and feasibility for the future EVEREST Tmod CAR T-cell trial. Methods: BASECAMP-1 (NCT04981119) patient eligibility has 2 parts: 1) Patients will be initially screened to identify germline HLA-A*02 heterozygosity by central NGS. If HLA-A*02 heterozygosity is confirmed, primary archival tumor tissue will be analyzed for somatic mutations by xT-Onco NGS testing. 2) If the tumor demonstrates HLA-A*02 LOH and the patient is eligible after screening, the patient will undergo leukapheresis. Banked T cells will be available for the autologous EVEREST Tmod CAR T-cell therapy interventional study to reduce waiting time at relapse. Clinical trial information: NCT04981119.

Background Pancreatic cancer has a poor prognosis and few choices of therapy. For patients with adequate performance status, FOLFIRINOX or gemcitabine plus nab-paclitaxel are preferred first-line treatment. 5-Fluorouracil (5-FU)–based therapy (e.g. FOLFIRI, OFF, or FOLFOX) are often used in patients who previously received gemcitabine-based regimens. A systematic review was conducted of the safety and efficacy of FOLFOX for metastatic pancreatic cancer following prior gemcitabine-based therapy. A Bayesian fixed-effect meta-analysis with adjustment of patient performance status (PS) was conducted to evaluate overall survival (OS) and compare outcomes with nanoliposomal irinotecan combination therapy. Methods PubMed.gov, FDA.gov, ClinicalTrials.gov, congress abstracts, Cochrane.org library, and EMBASE database searches were conducted to identify randomized controlled trials of advanced/metastatic disease, prior gemcitabine-based therapy, and second-line treatment with 5-FU and oxaliplatin. The database search dates were January 1, 1990–June 30, 2019. Endpoints were OS and severe treatment-related adverse events (TRAEs). Trial-level PS scores were standardized by converting Karnofsky grade scores to Eastern Cooperative Oncology Group (ECOG) Grade, and overall study-weighted PS was calculated based on weighted average of all patients. Results Of 282 studies identified, 11 randomized controlled trials (N = 454) were included in the meta-analysis. Baseline weighted PS scores predicted OS in 10 of the 11 studies, and calculated PS scores of 1.0 were associated with a median OS of 6.3 months (95% posterior interval, 5.4–7.4). After adjusting for baseline PS, FOLFOX had a similar treatment effect profile (median OS, range 2.6–6.7 months) as 5-FU/leucovorin plus nanoliposomal irinotecan therapy (median OS, 6.1 months; 95% confidence interval 4.8–8.9). Neutropenia and fatigue were the most commonly reported Grade 3–4 TRAEs associated with FOLFOX. Conclusions Baseline PS is a strong prognostic factor when interpreting the efficacy of 5-FU and oxaliplatin-based therapy of pancreatic cancer after progression on first-line gemcitabine-based regimens. When baseline PS is considered, FOLFOX has a similar treatment effect as 5-FU and nanoliposomal irinotecan therapy and a comparable safety profile. These findings suggest that 5-FU and oxaliplatin-based therapies remain an acceptable and alternative second-line treatment option for patients with pancreatic cancer and adequate PS (e.g. ECOG 0–1) following gemcitabine treatment.

BackgroundSolid tumors comprise >90% of cancers. Metastatic colorectal cancer, non-small cell lung cancer, and pancreatic cancer are among the leading causes of cancer-related mortality (5-year overall survival: 14%, 6%, and 3%, respectively).1Chimeric antigen receptor (CAR) T-cell therapy demonstrated clinical outcomes in hematologic malignancies.2 3 However, translating engineered T-cell therapies to solid tumors proves difficult due to a lack of tumor-specific targets that discriminate cancer cells from normal cells. In previous studies, the use of a carcinoembryonic antigen T-cell receptors and mesothelin CARs both resulted in dose-limiting on-target, off-tumor toxicities.4 5 TmodTM CAR T-cell therapy addresses these challenges by leveraging dual receptors to create a robust AND NOT signal integrator capable of killing tumor cells, while leaving healthy cells intact (figure 1).6 Tmod platform technology is a versatile system that may be applied to T cells and natural killer cells in autologous and allogeneic settings.HLA LOH offers a definitive tumor versus normal discriminator target for CAR T-cell therapy.6 7 The 2 receptors comprise an activator that recognizes an antigen present on the surface of normal and tumor cells and a blocker that recognizes a second surface antigen from an allele lost only in tumor cells. HLA LOH has been observed in ~13% across all solid tumors and up to 33% of pancreatic cancers.8 New technologies have shown higher HLA LOH rates; however, it is unclear whether patients with HLA LOH in their primary tumor tissues are at higher risk for recurrence. BASECAMP-1 is an observational study with key objectives: 1) To determine and identify patients with somatic HLA LOH eligible for Tmod CAR T-cell therapy, and 2) Subsequent leukapheresis and manufacturing feasibility for future Tmod CAR T-cell trials.MethodsBASECAMP-1 (NCT04981119) patient eligibility has 2 parts (figure 2): 1) Patients will be initially screened to identify germline HLA-A*02 heterozygosity by central next-generation sequencing (NGS). If HLA-A*02 heterozygosity is confirmed, primary archival tumor tissue will be analyzed by xT-Onco NGS testing9 to determine if somatic tumor HLA-A*02 LOH is present; 2) If the tumor demonstrates HLA-A*02 LOH and the patient screens eligible, the patient will undergo leukapheresis. Patients enrolled in the study who undergo leukapheresis will be evaluated for safety 7 days post-leukapheresis and followed for relapsed status. Banked T cells will be available for subsequent autologous Tmod CAR T-cell therapy at the time of relapse.Abstract 491 Figure 1Illustration of the Tmod T cell engaging with tumor cells with somatic loss of HLA-A*02 and with normal cellsAbstract 491 Figure 2Study schema. HLA, human leukocyte antigen; LOH, loss of heterozygosity; NGS, next generation sequencingTrial RegistrationNCT04981119ReferencesAmerican Cancer Society. Cancer Facts & Figures 2021. Atlanta: American Cancer Society; 2021.Neelapu S, Locke F, Bartlett N, et al. Axicabtagene ciloleucel CAR T-cell therapy in refractory large B-cell lymphoma. N Engl J Med 2017;377(26):2531–2544.Maude S, Laetsch T, Buechner J, et al. Tisagenlecleucel in children and young adults with B-cell lymphoblastic leukemia. N Engl J Med 2018;378(5):439–448.Parkhurst M, Yang J, Langan R, et al. T cells targeting carcinoembryonic antigen can mediate regression of metastatic colorectal cancer but induce severe transient colitis. Mol Ther 2011;19(3):620–626.Haas AR, Tanyi JL, O’Hara MH, et al. Phase I study of lentiviral-transduced chimeric antigen receptor-modified T cells recognizing mesothelin in advanced solid cancers. Mol Ther. 2019;27(11):1919–1929.Hamburger A, DiAndreth B, Cui J, et al. Engineered T cells directed at tumors with defined allelic loss. Mol Immunol 2020;128:298–310.Hwang M, Mog B, Douglass J, et al. Targeting loss of heterozygosity for cancer-specific immunotherapy. Proc Natl Acad Sci U S A 2021;118(12):e2022410118.The Cancer Genome Atlas (TCGA) Research Network. https://www.cancer.gov/tcga. Accessed June 2021.Perera J, Mapes B, Lau D, et al. Detection of human leukocyte antigen class I loss of heterozygosity in solid tumor types by next-generation DNA sequencing. J Immunother Cancer 2019;7(suppl 1):103.

Purpose To report planned final overall (OS) and progression-free survival (PFS) analyses from the phase II PEAK trial (NCT00819780). Methods Patients with previously untreated, KRAS exon 2 wild-type (WT) metastatic colorectal cancer (mCRC) were randomised to mFOLFOX6 plus panitumumab or bevacizumab. The primary endpoint was PFS; secondary endpoints included OS, objective response rate, duration of response (DoR), time to response, resection and safety. Treatment effect by tumour RAS status was a prespecified objective. Exploratory analyses included early tumour shrinkage (ETS) and depth of response (DpR). Results One hundred seventy patients had RAS WT and 156 had RAS WT/BRAF WT mCRC. Median PFS was longer for panitumumab versus bevacizumab in the RAS WT (12.8 vs 10.1 months; hazard ratio (HR) = 0.68 [95% confidence intervals (CI) = 0.48–0.96]; p = 0.029) and RAS WT/BRAF WT (13.1 vs 10.1 months; HR = 0.61 [95% CI = 0.42–0.88]; p = 0.0075) populations. Median OS (68% OS events) for panitumumab versus bevacizumab was 36.9 versus 28.9 months (HR = 0.76 [95% CI = 0.53–1.11]; p = 0.15) and 41.3 versus 28.9 months (HR = 0.70 [95% CI = 0.48–1.04]; p = 0.08), in the RAS WT and RAS WT/BRAF WT populations, respectively. Median DoR (11.4 vs 9.0 months; HR = 0.59 [95% CI = 0.39–0.88]; p = 0.011) and DpR (65.0 vs 46.3%; p = 0.0018) were improved in the panitumumab group. More panitumumab patients experienced ≥30% ETS at week 8 (64 vs 45%; p = 0.052); ETS was associated with improved PFS/OS. No new safety signals occurred. Conclusions First-line panitumumab + mFOLFOX6 increases PFS versus bevacizumab + mFOLFOX6 in patients with RAS WT mCRC. Electronic supplementary material The online version of this article (doi:10.1007/s00384-017-2800-1) contains supplementary material, which is available to authorized users.

Background Carcinoembryonic antigen (CEA) levels are used in conjunction with imaging to monitor response to systemic therapy in metastatic colorectal cancer (mCRC). We sought to identify a threshold for CEA change from baseline to predict progressive disease (PD) in mCRC patients receiving first-line therapy. Methods Patients from trials collected in the ARCAD database were included if baseline CEA was at least 10 ng/mL and repeat CEA was available within 14 days of first restaging scan. Optimal cutoffs for CEA change were identified by receiver operating characteristic analysis. Prediction performance of cutoffs was evaluated by sensitivity, specificity, and negative predictive value. Analyses were conducted by treatment class: chemotherapy alone, chemotherapy with anti-VEGF antibody, and chemotherapy with anti-EGFR antibody. Results A total of 2643 mCRC patients treated with systemic therapy were included. Median percent change of CEA from baseline to first restaging for patients with complete response, partial response, or stable disease (non-PD) and PD was −53.1% and +23.6% for chemotherapy alone (n = 957) and −71.7% and −45.3% for chemotherapy with anti-VEGF antibody (n = 1355). The optimal area under the curve cutoff for differentiating PD from non-PD on first restaging was −7.5% for chemotherapy alone and −62.0% for chemotherapy with anti-VEGF antibody; chemotherapy alone, adjusted odds ratio = 6.51 (95% CI = 3.31 to 12.83, P Conclusions Change in CEA from baseline to first restaging can accurately predict non-progression and correlates with long-term outcomes in patients receiving systemic chemotherapy.

3575 Background: Pts with mCRC frequently receive ≥1 sequential treatment TL. Approximately 50%-60% of pts receive second-line (L2) and 20%-30% third-line (L3) regimens in routine practice. We investigated the pts clinical/tumor characteristics and their prognostic impact across TL. Methods: Data from 37,560 pts enrolled in 48 randomized trials (34 in first (L1), 9 in L2, and 5 in L3) were analyzed. Candidate variables (VAR) measured at enrollment were sex, age, body mass index, performance status (PS), bilirubin, hemoglobin (Hb), platelets (Pl), derived white blood cells-to-absolute neutrophil counts ratio (WBC/ANC), lactate dehydrogenase (LDH), alkaline phosphatase (ALP), primary tumor location, and number and location of metastatic sites (MS). Missing data were imputed. VAR with significant value at all TL were selected to construct a prognostic score of overall survival (OS) in training set (TS, n=30,050; 80%). For each TL, the score was calculated as the sum on the estimations of the VAR’ coefficients from the common multivariate model; Cox’s model was used to define risk groups. The discrimination capability was assessed using the Harrell’s C-index. External validation was done in the validation set (VS, n=7,510; 20%). Results: A total of 26,974 pts in L1, 7,693 pts in L2 and 2,893 pts in L3 were analyzed. The following characteristics increased continuously over TL: ≥2 MS (57%, 72%, 82%), lung metastases (50%, 74%, 91%), lymph nodes metastases (51%, 61%, 80%), KRAS mutation (37%, 47%, 51%) and elevated ALP (46%, 52%, 61%). BRAF mutation decreased (9%, 7%, 5%). In L1 vs L3 trials, 70% vs 89% of patients had primary tumor resection, 10% vs 80% had at least one metastasectomy and 31% vs 78% had a late metachronous (>12 months) metastasis. 7 independent VAR were retained in the prognostic score (PS, Hb, Pl, WBC/ANC, LDH, ALP, and the number of MS); four pt groups with significantly different prognoses were defined (table). This score remained valid when excluding pts with PS 2. Third-line oral drugs (vs placebo) and subsequent line (L2/L1 or L3/L2) were effective in all prognostic groups. Conclusions: Clinical/tumor pt characteristics significantly varied over subsequent TL in patients included in randomized trials. The same prognostic model using practical clinical and biological variables can be used in all TL.[Table: see text]

4029 Background: The clearance of 5-FU differs significantly between men (M) and women (W). Adjuvant chemotherapy (CT) for CRC has a higher toxicity in W. The impact of sex on efficacy and toxicity in first-line trials of metastatic CRC (mCRC) is unknown. Methods: We analyzed patient (pt) and tumor characteristics, toxicities (nausea (AE1), vomiting (AE2), diarrhea, neutropenia (AE3)) and efficacy (overall survival (OS), progression-free survival (PFS)) according to sex in the following treatment groups: A: CT alone, B: CT + bevacizumab, C: CT + EGFR-antibodies, with subgroup analyses in the CT alone group for single-agent, doublets and triplets, as well as irinotecan- and oxaliplatin-based regimens. Pts from trials with treatments still used today and all relevant data available were eligible. OS and PFS were assessed using Kaplan-Meier and Cox models adjusted for primary tumor location and performance status (PS). Results: We included 28 trials with 18.399 pts (11.352 M and 7.047 W). W were younger (61 vs. 63 years), had more often a PS of 1 (49 vs 45%), BRAF mutations (10 vs. 7%), right-sided tumors (42 vs. 35%) and less often rectal tumors (26 vs. 32%). Significant differences in toxicity are reported in table. Rates of diarrhea were similar. There was no sex disparity in OS in the predefined subgroups except for pts receiving triplets where OS was better in M (HRadj=1.39 (1.05 - 1.85)). Median (interquartile range) OS in months for M and W was 16.7 (9.2-27.4) and 16.2 (8.9-27.2) in group 1, 21.9 (12.7-37.5) and 22.3 (12.9 – 39.0) in group 2, and 26.8 (14.6-45.3) and 24.8 (12.3-49.2) in group 3. HRsadj (W vs M) (95% CI), p values for OS were 1.02 (0.96-1.09), .557, 0.92 (0.83-1.03), .142, 0.99 (0.85-1.14), .866. Conclusions: M and W with mCRC differ significantly regarding patient and tumor characteristics. The significant higher toxicity in W does not translate in a higher treatment efficacy. Apart from known sex differences in pharmacokinetics of 5-FU, differences in pharmacodynamics must be postulated. [Table: see text]

Purpose To evaluate the efficacy of adding lapatinib to capecitabine and oxaliplatin (CapeOx) in patients with previously untreated human epidermal growth factor receptor 2 (HER2) –amplified advanced gastroesophageal adenocarcinoma. Patients and Methods Patients with HER2-positive advanced gastroesophageal adenocarcinoma were randomly assigned at a one-to-one ratio to CapeOx plus lapatinib 1,250 mg or placebo daily. Primary end point was overall survival (OS) in patients with centrally confirmed HER2 amplification in the primary efficacy population. Results A total of 545 patients were randomly assigned, and 487 patients comprised the primary efficacy population. Median OS in the lapatinib and placebo arms was 12.2 (95% CI, 10.6 to 14.2) and 10.5 months (95% CI, 9.0 to 11.3), respectively, which was not significantly different (hazard ratio, 0.91; 95% CI, 0.73 to 1.12). Median progression-free survival in the lapatinib and placebo arms was 6.0 (95% CI, 5.6 to 7.0) and 5.4 months (95% CI, 4.4 to 5.7), respectively (hazard ratio, 0.82; 95% CI, 0.68 to 1.00; P = .0381). Response rate was significantly higher in the lapatinib arm: 53% (95% CI, 46.4 to 58.8) compared with 39% (95% CI, 32.9 to 45.3) in the placebo arm (P = .0031). Preplanned exploratory subgroup analyses showed OS in the lapatinib arm was prolonged in Asian and younger patients. No correlation was observed between HER2 immunohistochemistry status and survival. There were increased toxicities in the lapatinib arm, particularly diarrhea. Conclusion Addition of lapatinib to CapeOx did not increase OS in patients with HER2-amplified gastroesophageal adenocarcinoma. There were clear differences in the effect of lapatinib depending on region and age. Future studies could examine this correlation.

RAS family proteins (including KRAS and NRAS) play important roles in the epidermal growth factor receptor (EGFR) signaling pathway. Mutations in RAS genes (occurring at loci in exons 2, 3, and 4) often result in constitutive activation of RAS proteins and persistent downstream signaling. Mutations in KRAS exon 2 (codon 12/13) are an established predictor of lack of response to the anti-EGFR monoclonal antibodies cetuximab and panitumumab in patients with metastatic colorectal cancer (mCRC), and have been used routinely in clinical practice to identify patients unlikely to derive benefit from these therapies. However, a meaningful proportion of patients with mCRC have tumors bearing other mutations in RAS genes. Recent studies have demonstrated that evaluation of an extended panel of RAS mutations—including mutations in KRAS exon 2, 3, and 4 and NRAS exons 2, 3, and 4—can better define the patient population that is unlikely to benefit from anti-EGFR therapy, with concomitant improvements in outcomes in the more highly selected RAS wild-type group. This discovery has changed the practice of oncology and has the potential to spare patients from exposure to ineffective therapy. In the near future, it is important for the oncology community to validate extended RAS analysis assays and make certain that patients who are candidates for anti-EGFR therapy undergo appropriate testing and treatment.

Our study was designed to evaluate the efficacy and safety of everolimus in patients with pre-treated metastatic gastric and esophagus cancers in a US-based population focusing on biomarker correlation. Patients with advanced upper GI adenocarcinomas who progressed after 1–2 prior regimens received everolimus 10 mg PO daily. The primary endpoint was disease control rate (DCR). Secondary endpoints included progression-free survival (PFS), toxicity, overall survival (OS) and biomarker correlatives of the mTOR pathway. Target accrual was 50 patients based on one-sided type I error of 10 % and power of 90 %. Forty-five patients were evaluable, 21 gastric, 11 esophagus and 13 from the GEJ. The median age was 64 (range 38–73); all patients had an ECOG of 0 or 1; and 18 patients (40 %) had only 1 prior regimen. The most common grade 3–4 adverse events included fatigue (24 %) and thrombocytopenia (22 %). We observed 1 partial response with 39 % of evaluable patients having stable disease. Median OS was 3.4 months (95 % CI 2.7–5.6 months), and PFS was 1.8 months (95 % CI 1.7–2.2 months). There was a strong correlation between ≥2 + IHC staining for p-S6 in tumor samples with better PFS (p

Purpose The objectives were to evaluate dosing schedules of labetuzumab govitecan, an antibody-drug conjugate targeting carcinoembryonic antigen-related cell adhesion molecule 5 (CEACAM5) for tumor delivery of 7-ethyl-10-hydroxycamptothecin (SN-38), in an expanded phase II trial of patients with relapsed or refractory metastatic colorectal cancer. Patients and Methods Eligible patients with at least one prior irinotecan-containing therapy received labetuzumab govitecan once weekly at 8 and 10 mg/kg, or two times per week at 4 and 6 mg/km on weeks 1 and 2 of 3-week repeated cycles. End points were safety, response, pharmacokinetics, and immunogenicity. Results Eighty-six patients who had undergone a median of five prior therapies (range, one to 13) were each enrolled into one of the four cohorts. On the basis of Response Evaluation Criteria in Solid Tumors 1.1, 38% of these patients had a tumor as well as plasma carcinoembryonic antigen reduction from baseline after labetuzumab govitecan treatment; one patient achieved a partial response with a sustained response spanning > 2 years, whereas 42 patients had stable disease as the best overall response. Median progression-free survival and overall survival were 3.6 and 6.9 months, respectively. The major toxicities (grade ≥ 3) among all cohorts were neutropenia (16%), leukopenia (11%), anemia (9%), and diarrhea (7%). The antibody-drug conjugate’s mean half-life was 16.5 hours for the four cohorts. Anti-drug/anti-antibody antibodies were not detected. The two once-weekly dose schedules, showing comparable toxicity and efficacy, were chosen for further study. Conclusion Monotherapy with labetuzumab govitecan demonstrated a manageable safety profile and therapeutic activity in heavily pretreated patients with metastatic colorectal cancer, all with prior irinotecan therapy. Further studies of labetuzumab govitecan treatment alone or in combination with other therapies in earlier settings are indicated.

Lessons Learned The safety profile in the gemcitabine/simtuzumab group was similar to that in the gemcitabine/placebo group. The addition of simtuzumab to gemcitabine does not improve clinical outcomes in patients with metastatic pancreatic adenocarcinoma Background The humanized IgG4 monoclonal antibody simtuzumab inhibits the extracellular matrix-remodeling enzyme lysyl oxidase-like 2 maintaining pathological stroma in tumors. Methods Adult patients with metastatic pancreatic adenocarcinoma (mPaCa) were randomly assigned to receive intravenous gemcitabine, 1,000 mg/m2, in combination with 200 or 700 mg simtuzumab or placebo. Primary endpoint was progression-free survival (PFS), secondary endpoints included overall survival (OS), objective response rate (ORR), and safety. Results Of 240 patients, 80 were randomly assigned to gemcitabine/simtuzumab 700 mg, 79 to gemcitabine/simtuzumab 200 mg, and 81 to gemcitabine/placebo. After a median follow-up of 3.0, 1.9, and 3.4 months for gemcitabine/simtuzumab 700 mg, gemcitabine/simtuzumab 200 mg, and gemcitabine/placebo, respectively, the median PFS was 3.7 months (adjusted hazard ratio [HR], 95% confidence interval [CI], p value vs placebo: 1.09 [0.74–1.61]; p = .73), 3.5 months (1.13 [0.76–1.66], p = .61]), and 3.7 months, respectively. Median OS was 7.6 months (0.83 [0.57–1.22]; p = .28), 5.9 months (1.07 [0.73–1.55]; p = .69), and 5.7 months, respectively. ORRs were 13.9%, 14.5%, and 23.5%, respectively. Simtuzumab was well tolerated. Conclusion The addition of simtuzumab to gemcitabine did not improve clinical outcomes in patients with mPaCa.

637 Background: Effective therapies are limited for advanced metastatic pancreatic ductal adenocarcinoma (PDAC) patients (pts) who have progressed after 1st line gemcitabine-based chemotherapy (Gem). FOLFOX has clinical benefit in Gem-refractory PDAC pts. A phase 1 trial demonstrated promising activity with pegilodecakin (PEG; pegylated IL-10) and FOLFOX in Gem-refractory PDAC pts, providing rationale for the phase 3 trial (SEQUOIA; NCT02923921). Methods: SEQUOIA is a randomized phase 3 study of FOLFOX alone or with PEG in Gem-refractory PDAC pts. Pts were randomized 1:1, excluding pts with prior surgery and radiation, and received FOLFOX ( dI-Leucovorin [400 mg/m2], oxaliplatin [85 mg/m2] followed by bolus 5-FU [400 mg/m2], and a 46-48 hr infusion of 5-FU [2400 mg/m2]) on day 1 of a 14-day cycle up to 12 cycles. PEG + FOLFOX arm received PEG (0.4 mg/d if ≤80kg and 0.8mg/d if > 80 kg) on Days 1-5 then Days 8-12 + FOLFOX. Pts could continue PEG monotherapy (0.8mg/d if ≤ 80 kg and 1.6 mg/d if > 80 kg) after FOLFOX discontinuation. Primary objective was OS. Secondary objectives included PFS, ORR per RECIST 1.1, and safety. Assuming OS HR of 0.74, the study was powered to 85% at 2-sided α = 0.05 with ~566 pts to detect superiority of PEG + FOLFOX. Results: As of Sept 9, 2019, 567 pts were randomized to PEG + FOLFOX (283) or FOLFOX (284). The majority (94.7%) had 1st line Gem+nab paclitaxel. The mOS was similar between FOLFOX + PEG arm [5.8 months] and FOLFOX arm [6.3 months] with HR = 1.045 (95% CI [0.863, 1.265], p = 0.6565). No statistical difference was observed for PFS, mPFS was 2.1 months in both arms with HR = 0.981, (95% CI [0.808, 1.190], p = 0.8144). ORR was 4.6% on the PEG+FOLFOX arm and 5.6% on the FOLFOX arm. Grade ≥3 adverse events that were 5% higher on the PEG+FOLFOX arm included thrombocytopenia (25.2% vs. 3.6%), anemia (16.2% vs. 4.0%), neutropenia (29.5% vs. 22.7%), and fatigue (17.6% vs. 10.8%). Conclusions: The addition of PEG to FOLFOX did not improve efficacy (OS, PFS, ORR) in advanced PDAC pts who have progressed after 1st line Gem-containing therapy. Safety findings were consistent with previous data observed from PEG + chemotherapy; toxicity was manageable and tolerable. Clinical trial information: NCT02923921.

114 Background: Magrolimab (M, Hu5F9-G4) is an antibody targeting CD47, a macrophage “don’t eat me” signal that demonstrates preclinical synergy with cetuximab (C) in refractory KRAS wild type (KRASwt) and KRAS mutant (KRASm) colorectal (CRC) tumors. Methods: Phase (Ph) 1 doses of M+C were escalated in solid tumor patients (pts) and Ph 2 efficacy was explored in previously treated KRASwt and KRASm CRC patients. Day 1 priming with 1 mg/kg of M was used to mitigate on-target anemia followed by maintenance doses ranging from 10 to 45 mg/kg in combination with C. Ph 2 pts were treated with 30 or 45 mg/kg of M and 400/250 mg/m2 of C. Results: In 78 treated pts (32 Ph 1 and 46 Ph 2), the median age was 59 years (range 19-82), and median prior therapies was 5 (range 1-14). No maximum tolerated dose was reached. Treatment-related adverse events (TRAEs) of any Grade (G) included dermatitis acneiform 36%, dry skin 33%, fatigue 32%, infusion reactions 31%, headache 30%, diarrhea 23%, nausea 23%, chills 23%, and anemia 22%. There were no fatal TRAEs and 3/78 (4%) discontinued M treatment due to any adverse events. In the combined Ph 1+2 study, 2 of 30 evaluable KRASwt CRC pts had confirmed PRs for 7.0 and 12.5 months (mo), for a 6.7% objective response rate (ORR). Both had prior C treatment. The median progression-free survival (mPFS) and median overall survival (mOS) was 3.6 mo (95%CI 1.8-5.4) and 10.1 mo (95%CI: 6.9-14.4), respectively. In 40 evaluable KRASm pts, there were no responses but 45% had stable disease (SD) and the mPFS and mOS were 1.9 mo (95%CI: 1.8-3.5) and 10.4 mo (95%CI: 5.7-16.4), respectively. In 28 KRASm pts who were TAS102/regorafenib naïve, preliminary mOS was 12.4 mo (95%CI: 5.9-not reached) which is longer than that reported for historical controls. Tumor biopsies showed treatment-related increases in macrophage immune cell infiltrates in SD pts, and baseline T cell infiltration was associated with longer OS. Pharmacokinetic profiles will be presented. Conclusions: M+C is a novel, well-tolerated combination immunotherapeutic treatment regimen. Responses were observed in two previously treated CRC pts and survival is encouraging in KRASm pts. Funded by Forty Seven and California Institute for Regenerative Medicine. Clinical trial information: NCT02953782.

Background. Meaningful anti-tumor immunity in cancer patients (pts) has been associated with the presence of specific T cells directed at neoantigens, a class of unique peptides that arise from tumor-specific mutations. ADXS-NEO, a personalized Listeria monocytogenes (Lm)-based immunotherapy, is a bioengineered Lmthat secretes an antigen-adjuvant fusion protein consisting of ≥ 20 unique (personal) neoantigens and a truncated fragment of listeriolysin O (tLLO), which has adjuvant properties. Preliminary safety and immunogenicity results from an ongoing Phase I trial with ADXS-NEO are herein reported. Methods. ADXS-NEO-02 is a Phase I dose-escalation study of ADXS-NEO in subjects with metastatic microsatellite stable colon cancer (CRC), metastatic squamous histology head and neck cancer, and metastatic non-small cell lung cancer (NSCLC). Manufacturing of ADXS-NEO starts with whole exome sequencing of each pt-matched normal and tumor samples to detect genetic alterations in the coding regions of the genome followed by its production under GMP specifications. ADXS-NEO is infused intravenously every 3 weeks until disease progression or limiting toxicity. Main endpoints include safety, tolerability and immune-correlative data. Results. The turnaround time for manufacturing ADXS-NEO has consistently been ≤ 8 weeks from biopsy to first dose. Two pts treated at 1X109 CFU (dose level 1) experienced dose limiting toxicities (i.e., Gr 3 hypoxia ± Gr 3 hypotension) within 4 hours of completing the infusion of the second dose. These acute adverse events correlated with elevation of serum IL-6 and other cytokines, and both cases were manageable and reversible with tocilizumab and/or steroids. A dose de-escalation cohort was initiated at 1X108 CFU, which has been found to be safe and tolerated by one pt. In these pts, ADXS-NEO induced: 1) activation and proliferation of CD4+ / CD8+ T cells; 2) neoantigen-specific T cell responses after 1 week of the initial priming dose and 3) antigen spreading and T cell responses to neoantigens not selected by algorithm. Conclusions. ADXS-NEO at 1X109 CFU was beyond the maximum tolerated dose but it was effective in eliciting a fast and broad anti-tumor immunity, including T cell responses to neoantigens and antigen spreading. Enrollment continues both in monotherapy and combination therapy arms with anti-PD-1/PD-L1 therapy, to define the recommended Phase II dose. Citation Format: J. Randolph Hecht, Jonathan W. Goldman, Sandy Hayes, David Balli, Michael F. Princiotta, Justin G. Dennie, John Heyburn, Tammy Sands, Sumitra Sheeri, Robert Petit, Andres A. Gutierrez, Frank Tsai. Safety and immunogenicity of a personalized neoantigen-Listeria vaccine in cancer patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr CT007.

11017 Background: Most GISTs are driven by mutations in KIT and PDGFRa and secondary mutations are felt to confer resistance to TKIs. In advanced/metastatic GIST, the benefit of second line TKIs and beyond is progressively less after imatinib failure. As such, novel non-TKI approaches are important to explore. Here we report interim analyses of safety and efficacy in advanced GIST patients treated with immunotherapy. Methods: Patients with advanced/metastatic GIST refractory to at least imatinib were enrolled on a randomized, parallel group, unblinded Phase 2 trial of either nivo (240 mg Q2wks) or nivo (240 mg Q2wks) with ipi (1mg/kg Q6wks) for up to 2 years. The primary endpoint was the objective response rate(ORR) of nivo alone or nivo + ipi by RECIST 1.1 criteria. Imaging was assessed by investigator and 3 independent radiologists. Patients were randomized 1:1 and were restaged every 8 weeks. With a sample size of 20 per group, an exact binomial test with a nominal 0.050 one-sided significance level will have 82% power to detect the difference between the null hypothesis response rate 1.5% and the alternative response rate of 15%. Secondary objectives are to ascertain the PFS, CBR, RR by Choi criteria and safety. Blood and biopsies are also being collected. Results: At cutoff, 29 patients (27 evaluable) with a median of 3 (1-7) lines of prior therapies have started on trial. In the nivo only arm, 7/15 pts had a best response of SD for a CBR of 46.7% with the median PFS being 8.57 wks. In the nivo + ipi arm, 1/12 patients had a PR and 2/12 have SD for a CBR of 25.0% (95% exact C.I. 5.5%-57.2%) with a median PFS of 9.1 wks. 8 patients have been on therapy for more than 6 months and two patients with a KIT Exon 17 mutation had radiographic disease shrinkage. Most AEs were grades 1-2 with fatigue (37%) being the most common. 4 Grade 3/4 AEs occurred in the nivo and ipi arm (hyperglycemia, weakness, diarrhea x 2) and 4 grade 3/4AEs occurred in the nivo arm (DKA, hyperglycemia, rash, fatigue). Pretreatment biopsies have been obtained in all patients and blood has been collected on all patients for correlative analysis. Conclusions: In a heavily pretreated GIST population, responses and disease control with both nivo and nivo + ipi were observed. To date, the drugs have been well tolerated and no new safety signals have been observed in this disease state. Clinical trial information: NCT02880020.

In this prospective referring-physician–based survey, we investigated the definite clinical impact of 68Ga-DOTATATE PET/CT on managing patients with neuroendocrine tumors (NETs). Methods: We prospectively studied 130 patients with 68Ga-DOTATATE PET/CT referred for initial or subsequent management decisions (NCT02174679). Referring physicians completed one questionnaire before the scan (Q1) to indicate the treatment plan without PET/CT information, one immediately after review of the imaging report to denote intended management changes (Q2), and one 6 mo later (Q3) to verify whether intended changes were in fact implemented. To further validate the Q3 responses, a systematic electronic chart review was conducted. Results: All 3 questionnaires were completed by referring physicians for 96 of 130 patients (74%). 68Ga-DOTATATE PET/CT resulted in intended management changes (Q2) in 48 of 96 patients (50%). These changes were finally implemented (Q3) in 36 of 48 patients (75%). Q3 responses were confirmed in all patients with an available electronic chart (36/96; 38%). Conclusion: This prospective study confirmed a significant impact of 68Ga-DOTATATE PET/CT on the intended management of patients with NETs (50% of changes) and notably demonstrated a high implementation rate (75%) of these intended management changes.

In this prospective referring-physician-based survey, we investigated the definite clinical impact of 68Ga-DOTATATE PET/CT on managing patients with neuroendocrine tumors (NETs). Methods: We prospectively studied 130 patients with 68Ga-DOTATATE PET/CT referred for initial or subsequent management decisions (NCT02174679). Referring physicians completed one questionnaire before the scan (Q1) to indicate the treatment plan without PET/CT information, one immediately after review of the imaging report to denote intended management changes (Q2), and one 6 mo later (Q3) to verify whether intended changes were in fact implemented. To further validate the Q3 responses, a systematic electronic chart review was conducted. Results: All 3 questionnaires were completed by referring physicians for 96 of 130 patients (74%). 68Ga-DOTATATE PET/CT resulted in intended management changes (Q2) in 48 of 96 patients (50%). These changes were finally implemented (Q3) in 36 of 48 patients (75%). Q3 responses were confirmed in all patients with an available electronic chart (36/96; 38%). Conclusion: This prospective study confirmed a significant impact of 68Ga-DOTATATE PET/CT on the intended management of patients with NETs (50% of changes) and notably demonstrated a high implementation rate (75%) of these intended management changes.

Purpose Factors contributing to early mortality after initiation of treatment of metastatic colorectal cancer are poorly understood. Materials and Methods Data from 22,654 patients enrolled in 28 randomized phase III trials contained in the ARCAD (Aide et Recherche en Cancérologie Digestive) database were pooled. Multivariable logistic regression models for 30-, 60-, and 90-day mortality were constructed, including clinically and statistically significant patient and disease factors and interaction terms. A calculator (nomogram) for 90-day mortality was developed and validated internally using bootstrapping methods and externally using a 10% random holdout sample from each trial. The impact of early progression on the likelihood of survival to 90 days was examined with time-dependent Cox proportional hazards models. Results Mortality rates were 1.4% at 30 days, 3.4% at 60 days, and 5.5% at 90 days. Among baseline factors, advanced age, lower body mass index, poorer performance status, increased number of metastatic sites, BRAF mutant status, and several laboratory parameters were associated with increased likelihood of early mortality. A multivariable model for 90-day mortality showed strong internal discrimination (C-index, 0.77) and good calibration across risk groups as well as accurate predictions in the external validation set, both overall and within patient subgroups. Conclusion A validated clinical nomogram has been developed to quantify the risk of early death for individual patients during initial treatment of metastatic colorectal cancer. This tool may be used for patient eligibility assessment or risk stratification in future clinical trials and to identify patients requiring more or less aggressive therapy and additional supportive measures during and after treatment.

Summary Background Bevacizumab improves the efficacy of oxaliplatin-based chemotherapy in metastatic colorectal cancer. Our aim was to assess the use of bevacizumab in combination with oxaliplatin-based chemotherapy in the adjuvant treatment of patients with resected stage III or high-risk stage II colon carcinoma. Methods Patients from 330 centres in 34 countries were enrolled into this phase 3, open-label randomised trial. Patients with curatively resected stage III or high-risk stage II colon carcinoma were randomly assigned (1:1:1) to receive FOLFOX4 (oxaliplatin 85 mg/m 2 , leucovorin 200 mg/m 2 , and fluorouracil 400 mg/m 2 bolus plus 600 mg/m 2 22-h continuous infusion on day 1; leucovorin 200 mg/m 2 plus fluorouracil 400 mg/m 2 bolus plus 600 mg/m 2 22-h continuous infusion on day 2) every 2 weeks for 12 cycles; bevacizumab 5 mg/kg plus FOLFOX4 (every 2 weeks for 12 cycles) followed by bevacizumab monotherapy 7·5 mg/kg every 3 weeks (eight cycles over 24 weeks); or bevacizumab 7·5 mg/kg plus XELOX (oxaliplatin 130 mg/m 2 on day 1 every 2 weeks plus oral capecitabine 1000 mg/m 2 twice daily on days 1–15) every 3 weeks for eight cycles followed by bevacizumab monotherapy 7·5 mg/kg every 3 weeks (eight cycles over 24 weeks). Block randomisation was done with a central interactive computerised system, stratified by geographic region and disease stage. Surgery with curative intent occurred 4–8 weeks before randomisation. The primary endpoint was disease-free survival, analysed for all randomised patients with stage III disease. This study is registered with ClinicalTrials.gov, number NCT00112918. Findings Of the total intention-to-treat population (n=3451), 2867 patients had stage III disease, of whom 955 were randomly assigned to receive FOLFOX4, 960 to receive bevacizumab–FOLFOX4, and 952 to receive bevacizumab–XELOX. After a median follow-up of 48 months (range 0–66 months), 237 patients (25%) in the FOLFOX4 group, 280 (29%) in the bevacizumab–FOLFOX4 group, and 253 (27%) in the bevacizumab–XELOX group had relapsed, developed a new colon cancer, or died. The disease-free survival hazard ratio for bevacizumab–FOLFOX4 versus FOLFOX4 was 1·17 (95% CI 0·98–1·39; p=0·07), and for bevacizumab–XELOX versus FOLFOX4 was 1·07 (0·90–1·28; p=0·44). After a minimum follow-up of 60 months, the overall survival hazard ratio for bevacizumab–FOLFOX4 versus FOLFOX4 was 1·27 (1·03–1·57; p=0·02), and for bevacizumab–XELOX versus FOLFOX4 was 1·15 (0·93–1·42; p=0·21). The 573 patients with high-risk stage II cancer were included in the safety analysis. The most common grade 3–5 adverse events were neutropenia (FOLFOX4: 477 [42%] of 1126 patients, bevacizumab-FOLFOX4: 416 [36%] of 1145 patients, and bevacizumab–XELOX: 74 [7%] of 1135 patients), diarrhoea (110 [10%], 135 [12%], and 181 [16%], respectively), and hypertension (12 [1%], 122 [11%], and 116 [10%], respectively). Serious adverse events were more common in the bevacizumab groups (bevacizumab–FOLFOX4: 297 [26%]; bevacizumab–XELOX: 284 [25%]) than in the FOLFOX4 group (226 [20%]). Treatment-related deaths were reported in one patient receiving FOLFOX4, two receiving bevacizumab–FOLFOX4, and five receiving bevacizumab–XELOX. Interpretation Bevacizumab does not prolong disease-free survival when added to adjuvant chemotherapy in resected stage III colon cancer. Overall survival data suggest a potential detrimental effect with bevacizumab plus oxaliplatin-based adjuvant therapy in these patients. On the basis of these and other data, we do not recommend the use of bevacizumab in the adjuvant treatment of patients with curatively resected stage III colon cancer. Funding Genentech, Roche, and Chugai.

Colorectal tumors that are wild-type (WT) for KRAS are often sensitive to EGFR blockade, but almost always develop resistance within several months of initiating therapy1,2. The mechanisms underlying this acquired resistance to anti-EGFR antibodies are largely unknown. This situation stands in marked contrast to that of small molecule targeted agents, such as inhibitors of ABL, EGFR, BRAF, and MEK, in which mutations in the genes encoding the protein targets render the tumors resistant to the effects of the drugs3–6. The simplest hypothesis to account for the development of resistance to EGFR blockade are that rare cells with KRAS mutations pre-exist at low levels in tumors with ostensibly WT KRAS genes. Though this hypothesis would seem readily testable, there is no evidence in pre-clinical models to support it, nor is there data from patients. To test this hypothesis, we determined whether mutant KRAS DNA could be detected in the circulation of 28 patients receiving monotherapy with panitumumab, a therapeutic anti-EGFR antibody. We found that nine of 24 (38%) patients whose tumors were initially KRAS WT developed detectable mutations in KRAS in their sera, three of which developed multiple different KRAS mutations. The appearance of these mutations was very consistent, generally occurring between five to six months following treatment. Mathematical modeling indicated that the mutations were present in expanded subclones prior to the initiation of panitumumab. These results suggest that the emergence of KRAS mutations is a mediator of acquired resistance to EGFR blockade and that these mutations can be detected in a non-invasive manner. Moreover, they explain why solid tumors develop resistance to targeted therapies in a highly reproducible fashion.