Predictive and prognostic features of metastatic colorectal cancer arising from the transverse colon: A pooled analysis of the CCTG/AGITG CO.17 and CO.20 randomized trials

124

Background: Primary tumour location is predictive of anti-EGFR benefit and prognostic in metastatic colorectal cancer (mCRC). Transverse colon cancers are often categorized as right sided, but the optimal cut point is unclear. Canadian Cancer Trials Group (CCTG)/Australasian Gastro-Intestinal Trials Group ( AGITG) CO.17 compared Cetuximab (Cet) vs. best supportive care (BSC) in mCRC. CCTG/AGITG CO.20 studied the addition of Brivanib Alaninate to Cet in pre-treated KRAS wildtype (WT) mCRC. We investigated the predictive and prognostic features of transverse colon primary location in a pooled cohort from these trials. Methods: Data from patients with RAS WT mCRC from CO.17 and KRAS WT mCRC from CO.20 randomized to cetux were analyzed for treatment outcomes according to location - right, transverse and left. The cecum to transverse colon was considered right sided, while the splenic flexure to rectum was considered left sided. Results: 553 patients were included, 201 (36.3%) from CO.17 and 352 (63.7%) from CO.20. Primary site distribution was: 32 (5.8%) transverse, 101 (18.3%) right and 420 (75.9%) left. On multivariate analysis from 457 (82.6%) patients treated with Cet, left side was associated with superior OS (HR, 0.40; 95% CI, 0.24-0.68, p=0.0006) and PFS (HR, 0.48; 95% CI,0.29-0.79, p=0.004) compared to transverse colon. No significant difference was noted in OS (HR, 0.74; 95% CI, 0.41-1.31, p=0.30) and PFS (HR, 0.79; 95% CI, 0.46-1.36, p=0.40) between right side versus transverse colon. Sidedness was not associated with prognostic difference in OS or PFS in the 96 (17.4%) patients receiving BSC alone. Outcomes according to primary site and treatment are shown. Conclusions: Transverse mCRC has comparable prognostic and predictive features to right sided mCRC. In keeping with previous studies, left side was predictive of greater Cet benefit and presented better overall prognosis when single agent Cet was used after 5-FU, oxaliplatin and irinotecan. [Table: see text]

nextHERIZON: A phase 2 study of HER-Vaxx, a HER2-targeting peptide vaccine, in combination with chemotherapy or pembrolizumab in patients with HER2 metastatic or advanced gastric/gastroesophageal adenocarcinoma that progressed on or after trastuzumab treatment

TPS481

Background: HER-Vaxx is a B-cell peptide vaccine composed of a fusion of 3 epitopes from the extracellular domain of HER2/neu conjugated to CRM197 with the adjuvant Montanide. Results from a phase 1b study revealed that active immunization with HER-Vaxx was well tolerated and induced HER2-dose dependent immune responses corresponding to tumor reduction in advanced gastric cancer (GC) or gastroesophageal adenocarcinoma (GEA) (Wiedermann, 2021). A phase 2 study, HERIZON, comparing HER-Vaxx plus standard chemotherapy or chemotherapy alone is currently enrolling. Pre-clinical data demonstrated a synergistic effect with combination of HER2 and PD-1 vaccines and 90% tumor growth inhibition (Kaumaya, 2020). Ramucirumab plus paclitaxel is an approved second-line treatment for patients with GC or GEA who have failed first-line treatment chemotherapy or trastuzumab (TRA) (Wilke, 2014). The nextHERIZON study seeks to evaluate the clinical benefit of adding HER-Vaxx to ramucirumab plus paclitaxel or pembrolizumab, following progression on TRA. Methods: nextHERIZON is phase 2, open-label, non-comparative, double arm, 2-stage design study in patients with confirmed AGC and HER2 overexpression following progression on or after TRA. Arm assignment depends on prior PD-1/PD-L1 inhibitor treatment. Arm 1 will receive HER-Vaxx + ramucirumab and paclitaxel. Arm 2 will receive HER-Vaxx + pembrolizumab. Up to 55 patients will be enrolled in each arm which includes a safety run-in phase. Arms will be analyzed independently. The key inclusion criteria are: patients ³ 18 year of age; ECOG 0 or 1; minimum life expectancy of 3 months; progressed on or after TRA; confirmed HER2 overexpression; at least one measurable lesion; adequate hematologic and organ function. Key exclusion criteria include previous treatment with trastuzumab-deruxtecan or any other anti-HER2 therapy other than trastuzumab. Arm 2 excludes prior therapy with anti- PD-1, PD-L1 or PD-L2 agents. The co-primary endpoints are safety and objective response rate (RECIST 1.1). Secondary objectives are efficacy and survival measures. HER-Vaxx is administered by intramuscular (IM) injection on Day 1, Day 15, and Day 29 and on Day 1 of each 2nd or 3rd cycle depending on arm. Dose-limiting toxicity (DLT) window is 29 days on treatment. Tumor assessment is evaluated at Day 43 then every 6 weeks until progression or withdrawal. This study is currently enrolling patients in Australia and US (Q1 2023). Clinical trial information: NCT05311176 .

INTEGRATE IIa: A randomised, double-blind, phase III study of regorafenib versus placebo in refractory advanced gastro-oesophageal cancer (AGOC)—A study led by the Australasian Gastro-intestinal Trials Group (AGITG)

LBA294

Background: AGOC has limited options after second-line therapy. Regorafenib (Rego), an oral multi-targeted tyrosine kinase inhibitor (TKI) targeting angiogenic, stromal and oncogenic receptor TKs, prolonged progression free survival (PFS) versus placebo (PBO) across all regions/subgroups in the INTEGRATE phase 2 randomised trial (JCO 2016 43(23):2728-2735). INTEGRATE IIa was designed to examine if Rego improves overall survival (OS). Methods: Double-blind placebo-controlled phase 3 trial comparing Rego + best supportive care (BSC) vs PBO + BSC using 2:1 randomisation, stratified by tumour location (GO junction vs gastric), geographic region (Asia vs rest of world), prior VEGF inhibitors (Y/N). Eligibility criteria: histologically/cytologically confirmed AGOC, evaluable metastatic/locally advanced disease, failure/intolerance of ≥ 2 prior lines of therapy with a platinum agent + fluoropyrimidine. Primary objective: OS in the whole study population. OS among Asian sub-population is a key secondary objective. Target of at least 221 events from 250 patients provides 80% power to detect an OS hazard ratio (HR) of 0.67. Pooled OS analysis incorporating INTEGRATE phase 2 data is also planned. Secondary endpoints include PFS, objective response rate, safety and quality of life. Results: 251 patients enrolled (Oct16 - Sep21) from 5 countries:157 from Asia (Korea, Taiwan, Japan);169 Rego and 82 PBO. After 238 events, median OS (in months) for Rego vs PBO was 4.5 vs 4.0 (HR 0.70 [95%CI: 0.53 to 0.92]; p = 0.011) in the whole study population, with a 12 mo survival of 19% vs 6%. Median PFS was 1.8 v 1.6 (HR = 0.52; [95%CI: 0.40-0.69]; p = < .0001). After pre-planned adjustment for multiplicity, there were no statistically significant differences across regions (Asia versus non-Asia) or other pre-specified subgroups. Pooled analysis median OS was 5.0 v 4.1 (HR 0.69 [95% CI:0.56 to 0.87]; p = 0.001). Rego toxicity was similar to previously reported. Conclusions: Rego improves survival compared with PBO in advanced refractory AGOC, offering a new treatment option. This result creates a therapeutic platform for combination studies. INTEGRATE IIb is an ongoing international randomised Phase 3 trial in pre-treated patients with AGOC comparing Rego + nivolumab to standard chemotherapy (NCT0487936). Clinical trial information: NCT02773524 .

SPAR: A randomized placebo-controlled phase 2 trial of simvastatin in addition to standard chemotherapy and radiation in preoperative treatment for rectal cancer: An AGITG clinical trial

TPS3646

Background: In retrospective studies statin use during preoperative chemo-radiation (pCRT) for rectal cancer is associated with improved overall survival, pathological tumor response and treatment toxicity. In vivo preclinical studies show that statins radiosensitize cancer cells, with improved tumor control and reduced radiation-induced gastrointestinal (GI) and skin toxicities. A prospective randomized trial is justified to confirm these clinically important benefits. Tumor regression following pCRT has strong prognostic significance, as assessed radiologically (MRI-based tumor regression grading [mrTRG]) prior to, or pathologically (pathTRG) following, surgery. Using mrTRG after each treatment phase in total neoadjuvant therapy (TNT) programs could assess incremental tumor regression and optimize patient management including surgery. Methods: Design: This double-blind phase 2 trial is recruiting 222 patients planned to receive long-course fluoropyrimidine-based pCRT for rectal adenocarcinoma at 17 sites in New Zealand and Australia. Patients are randomized to simvastatin 40mg or placebo daily for 90 days, starting 1 week prior to pCRT, with minimization for major prognostic variables. Pelvic MRI at baseline and 6-8 weeks after pCRT will assess mrTRG. A protocol amendment allows TNT using consolidation chemotherapy after pCRT; MRI timing is unchanged. Primary objective: comparison of rates of grades 1-2 mrTRG following pCRT with simvastatin or placebo, considering mrTRG in 4 ordered categories (1, 2, 3, 4-5). Secondary objectives: comparison of rates of grades 1-2 pathTRG in resected tumors; incidence of > grade 2 acute GI and non-GI adverse events (AE); incidence of late GI AE; compliance with intended pCRT and trial medication; proportion of patients undergoing surgical resection post-pCRT; 3-year local recurrence rate, disease-free and cancer-specific survival; and pathological scores for radiation colitis. Tertiary and correlative objectives: association between mrTRG and pathTRG grouping; inter-observer scoring agreement on mrTRG and pathTRG; comparison of the association between tumor CD3+ and/or CD8+ T-cell infiltrates in diagnostic biopsies and pathTRG; intensity and distribution of subsets of infiltrating T-cells in irradiated resected normal and malignant tissue; and the effect of simvastatin on markers of systemic inflammation (modified Glasgow prognostic score and the neutrophil-lymphocyte ratio). Eligibility criteria exclude statin use within 6 weeks prior to trial entry, patients intolerant of statins, and planned use of oxaliplatin or biological agents during pCRT. Trial recruitment commenced April 2018 and 95 of 222 patients have been recruited as at 21 January 2022. Clinical trial information: ACTRN12617001087347.

Largest evaluation of acquired resistance to sotorasib in KRAS p.G12C-mutated non–small cell lung cancer (NSCLC) and colorectal cancer (CRC): Plasma biomarker analysis of CodeBreaK100

102

Background: Sotorasib, a specific, irreversible KRASG12C inhibitor, has been approved in multiple countries for adults with KRAS p.G12C-mutated locally advanced or metastatic NSCLC who received prior systemic therapy based on the global phase 1/2 CodeBreaK100 trial. Here we describe putative mechanisms of acquired resistance to sotorasib from the largest single dataset evaluated to-date. Methods: Patients with advanced KRAS p.G12C-mutated NSCLC or CRC from the CodeBreaK100 Ph1/2 trial who received sotorasib monotherapy at 960 mg once daily were analyzed for efficacy. Primary endpoint was objective response rate (ORR) assessed by central review. To investigate biomarkers of resistance to sotorasib, an exploratory endpoint was defined to examine acquired genomic alterations at disease progression. Plasma samples collected at baseline and progression were analyzed for genomic alterations with the 23-gene Resolution Bioscience ctDx Lung test for NSCLC and the 74-gene Guardant 360 ctDNA test for CRC. Acquired genomic alterations were defined by their absence at baseline and presence at progression. Results: In 174 pts with NSCLC and 91 pts with CRC-treated with sotorasib, the ORR were 41% and 12% respectively. Median progression-free survival and median overall survival were 6.3 months (mos) and 12.5 mos for NSCLC pts and 4.2 mos and 13.4 mos for CRC pts (median follow-up: 22.5 mos NSCLC; 12.5 mos CRC). A total of 67 NSCLC pts and 45 CRC pts had a plasma sample sequenced both at baseline and at progression. At least one new acquired genomic alteration at progression was detected in 19 (28%) NSCLC pts and in 33 (73%) CRC pts (Table). The acquired genomic alterations were heterogeneous in both NSCLC and CRC, with variants detected across multiple genes and pathways. The most prevalent putative pathway of resistance in both NSCLC and CRC was the receptor tyrosine kinase (RTK) pathway. Secondary RAS alterations occurred more frequently in CRC versus NSCLC pts (16% vs. 3%). Conclusions: Based on the largest descriptive dataset to-date, diverse mechanisms of acquired resistance occur in KRAS p.G12C-mutated NSCLC and CRC pts treated with sotorasib. New RTK pathway alterations frequently emerged at progression, highlighting the potential role for combining sotorasib with upstream inhibitors of RTK, such as SHP2 or EGFR inhibitors. Serial plasma DNA analysis revealed acquired resistance patterns that support the development of KRASG12C inhibitor combination therapies. Clinical trial information: NCT03600883. [Table: see text]

Patterns of care and survival of first line anti-EGFR therapy; results from South Australian (SA) metastatic colorectal (mCRC) registry

e15577

Background: Treatment of mCRC has changed dramatically over the last decade with therapy guided by clinical and molecular features which include side of primary, RAS, BRAF and MMR status. For left sided RAS WT mCRC survival is optimized by using first line anti-EGFR anti-bodies combined with chemotherapy. This is reflected in modern guidelines. Methods: We aim to assess the uptake of first line anti-EGFR/chemotherapy combinations in patients with mCRC and assess for difference between cetuximab (C) and panitumumab (P) use from the SAmCRCR. The real word registry has collected data from all patients diagnosed with mCRC in SA prospectively since 2/2006. We compared RAS WT patients treated with chemo/bevacizumab (CB). Survival was analysed using the Kaplan Meier method. Results: Of the 5537 patients currently entered onto the registry, only 97 had RAS status recorded and had received first line anti-EGFR/chemotherapy (FaEC). 102 patients were RAS WT and received CB. Table summarises patient characteristics and median OS for FaEC (C or P) and CB. There was no statistical difference in survival for C v P (p = 0.055). Conclusions: When comparing C & P choice in first line therapy, C was more often combined with irinotecan/chemo. C patients had higher rate of left sided primary. There were lower rates of liver resection in patients treated with C which may explain the numerically lower median overall survival. An updated cohort analysis will be included to assess changes in practice over time.[Table: see text]

Australasian Gastrointestinal Trials Group (AGITG) CONTROL NET Study: 177Lu-DOTATATE peptide receptor radionuclide therapy (PRRT) and capecitabine plus temozolomide (CAPTEM) for pancreas and midgut neuroendocrine tumours (pNETS, mNETS)—Final results

4122

Background: CAPTEM is an accepted regimen for patients (pts) with advanced pNETs. Single agent PRRT is now a standard of care for progressive WHO Grade 1/2 mNETs. High activity was seen with PRRT/CAPTEM in a single arm Phase I/II trial. This study aims to determine the activity of combining CAPTEM with PRRT in mNETs and pNETs pts. Methods: Non-comparative randomised open label parallel group phase II trial with 2:1 randomisation to PRRT/CAPTEM (experimental arm) vs. PRRT (mNETs control) and CAPTEM (pNETS control). PRRT/CAPTEM: 7.8GBq 177Lu Octreotate (Lutate) given intravenously (IV) on day 10 every 8 weeks for 4 cycles, with concurrent oral capecitabine 750mg/m2 b.i.d. days 1-14 and temozolomide 75mg/m2 b.i.d. days 10-14 every 56 day cycle, up to 4 cycles. PRRT alone: 7.8GBq 177Lu Octreotate (Lutate) given intravenously (IV) on day 1 every 8 weeks for 4 cycles. CAPTEM alone: Oral capecitabine 750mg/m2 b.i.d. days 1-14 and days 29-42; Oral temozolomide 75mg/m2 b.i.d. days 10-14 and 38-42 every 56 day (8w) cycle. Primary endpoint: Progression free survival (PFS). mNETS: At 15 months, assuming PFS 66.4% in control arm; target PFS ³ 80%; pNETS: At 12 months, assuming PFS 60% in control arm; target PFS ³ 75%. Secondary endpoints: Objective tumor response rate (complete or partial) (OTRR), overall survival (OS), adverse events (AEs). Results: 75 pts enrolled (Dec 2015 – Nov 2018): mNETs 33 PRRT/CAPTEM, 14 PRRT, median follow up (mFU) 60.3 months; pNETS 19 PRRT/CAPTEM, 9 CAPTEM, mFU 57.5 months (mo). Late Grade 3/4 haematologic AEs: mNETS: 2/32 (6%) PRRT/CAPTEM pts and 4/13 (31%) PRRT pts. Events included myelodysplastic syndrome (40 mo), leukaemia (60 mo), pancytopenia (50 mo), anaemia (32 mo), thrombocytopenia (7 mo). No late haematologic G3/4 AEs were reported in the pNETS cohort. No late renal toxicity was identified in all study arms. Conclusions: CONTROL NETs is the first randomized trial to demonstrate efficacy for PRRT in pNETs, in addition to a standard of care. Extended follow up confirms durable CAPTEM/PRRT activity, with superior PFS in pNETs. Late haematologic toxicity was seen in both mNET PRRT arms but was not higher with additional CAPTEM. The activity of CAPTEM/PRRT in pNETs should be tested in the phase III setting. Clinical trial information: ACTRN12615000909527. [Table: see text]

Phase I study of autolytic immunotherapy of metastatic neuroendocrine tumors using intralesional rose bengal disodium

4115

Background: Metastatic neuroendocrine neoplasms (mNEN) originating in the gastrointestinal tract are frequently slow growing yet both symptom and disease control remain important. Treatment options include resection, systemic somatostatin analogues (SSA), and systemic peptide receptor radionuclide therapy (PRRT). Additional options are needed; we have explored intralesional (IL) rose bengal disodium (PV-10), an investigational autolytic immunotherapy that can yield immunogenic cell death and disease-specific functional adaptive immunity. Methods: This phase 1 study evaluated safety, tolerability and impact on symptoms and biochemical markers resulting from IL PV-10 administered percutaneously to hepatic lesions in patients (pts) with progressive mNEN not amenable to resection or other potentially curative therapy. Eligible lesion(s) were 1.0 - 3.9 cm in longest diameter with amount of PV-10 administered proportional to size. Cohort 1 (n = 6 pts) received PV-10 to a single lesion per treatment cycle; Cohort 2 (n = 6) could receive injection to multiple lesions per treatment cycle. Pts could receive further PV-10 ≥6 weeks after prior injection. The primary endpoint was safety. Secondary endpoints included objective response rate (ORR) assessed by contrast enhanced CT (RECIST 1.1) and 68Ga-DOTATATE PET, biochemical response (CgA) and patient-reported outcome (EORTC QLQ-C30 and GI.NET21 QOL instruments). Results: Twelve pts were enrolled, 50% male, median age 66 yrs (range 47-79). Primary sites: 7 small bowel, 2 pancreas, 1 caecal, 2 unknown; grade: Gd1 = 5, Gd2 = 7. All pts had received SSA and PRRT as part of previous therapy and all had symptomatic, progressive disease. Median CgA was 1585 (range 35-10370). One lesion was injected per cycle for all 12 pts; none were suitable for multiple injections. One pt received 4 sequential PV-10 treatment cycles, 3 received 2 cycles, and 8 received 1 cycle. Toxicity was consistent with experience in other hepatic malignancies: post-procedure pain was reported by most pts; grade 3 photosensitivity reaction occurred in 1 pt; and grade 1 elevation of hepatic enzymes attributed to PV-10 occurred in 2 pts, resolving by day 7. Additionally, carcinoid flare occurred in 1 pt. ORR of injected lesions was 42%; patient-level disease control was 84%. Estimated PFS was 9.2 months; median OS was 22.5 months. CgA remained stable in 10 pts and upregulation of NK and activated CD4+ T lymphocytes was observed post-injection. QOL data at months 1 and 3 showed stable or improved carcinoid symptoms and global health status in 9 pts. Conclusions: PV-10 elicited no safety concerns with encouraging evidence of both local and systemic disease and symptom control in a heavily pre-treated population. Multiple cycles were delivered safely in suitable patients. Adaptive immune upregulation is consistent with other solid tumors and supports potential systemic benefit. Clinical trial information: NCT02693067.

Australasian Gastrointestinal Trials Group (AGITG) CONTROL NET Study: Phase II study evaluating the activity of 177Lu-Octreotate peptide receptor radionuclide therapy (LuTate PRRT) and capecitabine, temozolomide CAPTEM)—First results for pancreas and updated midgut neuroendocrine tumors (pNETS, mNETS)

4608

Background: CAPTEM is an accepted regimen for patients (pts) with advanced pNETs. Single agent 177Lu-Octreotate PRRT is now a standard of care for progressive WHO Grade (G) 1/2 mNETs. High activity was seen with LuTate/CAPTEM in a single arm Phase I/II trial. This study was undertaken to determine the relative activity of adding CAPTEM to LuTate PRRT in pts with mNETs and pNETs. Methods: Non-comparative randomised open label parallel group phase II trial with 2:1 randomisation to PRRT/CAPTEM (experimental arm) vs. PRRT (mNETs control) and CAPTEM (pNETS control). PRRT/CAPTEM: 7.8GBq LuTate day(D) 10, 8 weekly (wkly) x 4, with b.i.d. oral CAP 750mg/m2 D1-14 & TEM 75mg/m2D10-14, 8 wkly x 4; PRRT: 8 wkly x 4; CAPTEM 8 wkly x 4. Primary endpoint: Progression free survival (PFS). mNETS- at 15 months (mo) assuming 15mo PFS 66.4% in control arm, aiming for PFS ³ 80%; pNETS- at 12mo assuming 12mo PFS 60% in control arm, aiming for PFS ³ 75%. Secondary endpoints: Objective tumour response rate (complete or partial) (OTRR), clinical benefit rate (OTRR, stable disease) (CBR), toxicity, quality of life. Results: 75 pts enrolled (Dec 2015 – Nov 2018): mNETs 33 PRRT/CAPTEM and 14 PRRT; pNETS 19 PRRT/CAPTEM and 9 CAPTEM. mNETS: Median follow-up 35mo; 15mo PFS was 90% (95% CI: 73-97%) v 92% (95% CI: 57-99%); OTRR 31% vs 15%; and CBR 97% vs 92% for PRRT/CAPTEM v PRRT respectively. Treatment related adverse events (AEs): 24/32 PRRT/CAPTEM pts had at least one G3 event (75%) vs 5/13 (38%, PRRT); and 4/32 pts at least one G4 event (13%) v 1/13 (8%) respectively, mostly haematologic (haem). Only one patient failed to complete therapy (PRRT/CAPTEM). pNETS: Median follow-up 34mo; 12mo PFS was 76% (95% CI: 48-90%) v 67% (95% CI: 28-88%); OTRR 68% vs 33%; and CBR 100% vs 100% for PRRT/CAPTEM v CAPTEM respectively. Treatment related AEs: 5/18 PRRT/CAPTEM pts had at least one G3 event (28%) vs 3/9 (33%) CAPTEM; 3/18 pts at least one G4 event (17%) v 1/9 (11%) respectively. Conclusions: CAPTEM/PRRT is active, meeting its target landmark PFS for CAPTEM/PRRT (12mo pNETs; 15mo mNETs) with numerically greater OTRR in both pNETs and mNETs, but with more haem toxicity in mNETs. As activity was high in both control arms longer follow up is required to determine if the relative activity of PRRT/CAPTEM is sufficient to warrant Phase III evaluation. Clinical trial information: ACTRN12615000909527 .

Cohort 1 results of a phase I study of autolytic immunotherapy of metastatic neuroendocrine neoplasms using intralesional rose bengal disodium

e16694

Background: Metastatic neuroendocrine neoplasms (mNEN’s) originating in the gastrointestinal tract are frequently slow growing yet both symptom and disease control remain important. Treatment options include resection, chemoablation, systemic somatostatin analogues (SSA) or peptide receptor radionuclide therapy (PRRT), but additional options are needed, especially when available options have been exhausted. Intralesional (IL) rose bengal disodium (PV-10), an autolytic immunotherapy under development for solid tumors, is being investigated as a potential option for treatment-refractory patients (pts) with hepatic metastases. Methods: This phase 1 study is evaluating the safety, tolerability and objective response resulting from percutaneous administration of PV-10 in 12 pts with progressive mNEN refractory to SSA and PPRT; pts must have at least one injectable hepatic lesion (1.0-3.9 cm in longest diameter) not amenable to resection or other potentially curative therapy. In Cohort 1 (n = 6) pts received PV-10 to a single hepatic lesion per treatment cycle, and could receive PV-10 to additional uninjected hepatic lesions ≥6 weeks after prior injection. The primary endpoint is safety. Secondary endpoints include objective response rate assessed by independent review of contrast enhanced CT and by 68Ga-DOTATATE PET. Results: Cohort 1 has fully enrolled, with 4 of 6 pts male, median age 65 yrs, range 47-72. Primary sites were: small bowel 3, pancreas 2, caecal 1. NET grade: Gd1 = 5, Gd2 = 1. All pts had progressed on prior SSA and PRRT. Median baseline CgA was 645 (range 30-2819). One pt received 4 PV-10 treatment cycles, 1 received 2 cycles, and 4 received a single cycle. Toxicity was acceptable, including transient pain post procedure, carcinoid flare and nausea. A partial response of injected lesions was observed in 50% of pts (injected lesion progression in 1 pt), with an overall response of stable disease achieved in 84% of pts by RECIST 1.1 (progressive disease in 1 pt). Progression free survival (PFS) was not reached by CT (range 2.4-25.3+ months), and was 6.1 months by PET. Median overall survival (OS) was ≥22.5 months, with three subjects alive at the data cut-off of Jan 2020 (range 18.1-33.8 months). Conclusions: Hepatic IL PV-10 elicited no safety concerns with encouraging evidence of both local response of injected tumors and prolonged systemic disease control in some pts. Enrolment to Cohort 2 is nearing completion where an additional 6 pts may receive injection of multiple lesions per treatment cycle. Clinical trial information: NCT00986661 .

CodeBreak 100: Activity of AMG 510, a novel small molecule inhibitor of KRASG12C, in patients with advanced colorectal cancer

4018

Background: Kirsten rat sarcoma viral oncogene homolog (KRAS) p.G12C mutation is associated with poor prognosis in colorectal cancer (CRC). AMG 510 is a first-in-class small molecule that specifically and irreversibly inhibits KRASG12C by locking it in the inactive guanosine diphosphate-bound state. In a previous interim analysis of the phase 1, first-in-human trial of AMG 510, we observed a favorable safety profile and preliminary antitumor activity in patients (pts) with advanced solid tumors harboring KRAS p.G12C. Here, we present updated data in pts with CRC. Methods: Key inclusion criteria were KRAS p.G12C mutation identified through molecular testing, measurable disease, and progression on standard therapy. Primary endpoint was safety. Secondary endpoints were objective response rate (ORR), disease control rate (DCR), progression-free survival (PFS), as assessed per RECIST 1.1, and overall survival (OS). Oral daily doses of 180, 360, 720, and 960mg were tested in the dose escalation phase, and 960mg dose was selected for the expansion phase. Results: As of Jan 8, 2020, 42 pts with CRC (21 female [50%], median age: 57.5 years [range: 33–82]) were enrolled and dosed (25 on 960mg). All pts received prior systemic therapies; 19 pts (45.2%) received > 3 prior lines. Median follow-up was 7.9 months (mos) (range: 4.2–15.9). 13 pts (31.0%) died, and 8 pts (19.0%) remained on treatment (tx). 22 (52.4%) and 8 (19.0%) pts had remained on tx for more than 3 and 6 months, respectively. Progressive disease was the most common reason for tx discontinuation. 20 pts (47.6%) had tx-related adverse events (TRAEs): 18 (42.9%) had grade 2 or lower TRAEs; 2 (4.8%) had grade 3 TRAEs, which were diarrhea (2.4%) and anemia (2.4%). There were no dose-limiting toxicities, fatal TRAEs, or TRAEs leading to tx discontinuation. Overall, ORR and DCR were 7.1% (3/42) and 76.2% (32/42), respectively. At 960mg, ORR and DCR were 12.0% (3/25) and 80.0% (20/25). 3 pts with PR had duration of response of 1.5, 4.2, and 4.3 months, respectively, and their responses were still ongoing at data cutoff. In all pts treated with all doses, median duration of stable disease was 4.2 mos (range: 2.5[+]–11.0). PFS/OS will be reported. Conclusions: In pts with heavily pretreated KRAS p.G12C mutant CRC, AMG 510 monotherapy was well tolerated, with the majority of pts achieving disease control. Study is ongoing. Clinical trial information: NCT03600883 .

Prognostic differences of RAS mutations: Results from South Australian (SA) metastatic colorectal (mCRC) registry

4067

Background: Effective targeting of RAS mutations has proven elusive until recently. AMG 510, a novel agent which targets KRAS G12C mutations (G12C MT), has shown promise in early phase clinical trials that included patients with mCRC. Prior reports have suggested that G12C MT may be predictive of poor outcome. Methods: We aimed to assess the prognostic implications of individual RAS in a population-based registry. The SAmCRCR collects data from all patients diagnosed with mCRC in South Australia prospectively. Individual RAS mutation data from patients entered into the SAmCRCR between February 2006 and December 2018 was reviewed. Survival was analysed for the more frequent mutations using Kaplan Meier method. Results: 1605 (33%) of the 4905 patients entered onto the registry had RAS mutation results available. Of these, 658 (41%) had RAS MT. The nature of the RAS MT was available in 563 (85.7% of those with RAT MT). Patient characteristics, frequency of individual RAS MT and median overall survival (OS) per RAS MT are noted in table. Low frequency MT made up an additional 16.3%. There were numerical differences in survival however there was no statistical difference in survival when comparing the various RAS MT, including the comparison of G12C to G12S (p = 0.38). Conclusions: Whilst the G12S mutation was associated with the longest survival numerically, the observed survival for patients with the most common RAS mutations (G12C, G12V, G12A, G12D and G13D) did not significantly differ. [Table: see text]

Regorafinib outcomes from the population-based South Australian mCRC registry (SAmCRCR)

e19344

Background: Regorafinib has been shown to improve survival over BSC alone in large randomized trials. The median survival in the CORRECT study was 6.4 months and 12 month survival 24.3%. In Australia regulators have limited the use of regorafenib and patients are required to self-fund. Understanding the potential benefit of regorafenib in a real world non trial setting would be informative for consumers when considering self funding. Methods: The SAmCRCR collects all mCRC patients prospectively. The Registry was analysed for patients who had received regorafinib between February 2006 and December 2018. Survival was analysed using Kaplan Meier method. Results: Only 53 patients have received regorafenib therapy since February 2006. The median age was 66 (range 34-82). 66% were male, 66% had stage IV at diagnosis, 53% had liver only, 13% liver and lung and 6% lung only involvement. 75% were left sided. K/RAS was available in 35/53 patients, 49% WT. BRAF in 8/53, 25% MT. MSI measured in 14, and MSI-H 21%. Prior lines of treatment received: one 4%, two 9%, three 23%, four 26%, > four 37%. Prior biological use: bevacizumab 72%, anti-EGFR 100% (for RAS WT). Median survival from diagnosis was 3.3 years (95% CI 2.8-3.8 years). From start of regorafinib median survival was 7.1 months (95% CI 4.8-9.4 months) and12 month survival 28%. Conclusions: The outcome for those patients who do access regorafinib is in keeping with that reported from large randomized trials and thus clinicians can quote these outcomes when discussing access to regorafinib in the community.

First results for Australasian Gastrointestinal Trials Group (AGITG) control net study: Phase II study of 177Lu-octreotate peptide receptor radionuclide therapy (LuTate PRRT) +/- capecitabine, temozolomide (CAPTEM) for midgut neuroendocrine tumors (mNETs)

604

Background: Single agent 177Lu-octreotate peptide receptor radionuclide therapy is now a standard of care for progressive mNETS. High activity was seen with LuTate and concurrent CAPTEM chemotherapy in a single arm Phase I/II trial. This study was undertaken to determine the relative activity of adding CAPTEM to LuTate PRRT in patients with mNETs. Methods: Non-comparative randomised open label phase II trial of PRRT +/- CAPTEM in patients with mNETs, with 2:1 randomisation: PRRT /CAPTEM (experimental arm) vs. PRRT (control). PRRT /CAPTEM: 7.8GBq LuTate day(D) 10, 8 weekly (wkly) x 4, with b.i.d. oral CAP 750mg/m2 D1-14 & TEM 75mg/m2 D10-14, 8 wkly x 4, vs. PRRT 8 wkly x 4. Primary endpoint: progression free survival (PFS) at 15 months assuming 15 month PFS of 66.4% in the control arm, aiming for PFS rate > 80%; secondary endpoints: objective tumour response rate (complete or partial response) (OTRR), clinical benefit rate (complete or partial response, stable disease) (CBR), toxicity, and QOL. Results: 47 patients enrolled (Dec 2015 - Feb 2018): 33 PRRT/CAPTEM and 14 PRRT. Two patients withdrew prior to treatment. Patient characteristics were balanced except gender (female 58% vs. 14%). Two patients received 2 prior systemic regimens. After a median follow-up of 32 months, the 15 month PFS was 90% (95% CI: 73-97%) v 92% (95% CI: 57-99%); OTRR 25% vs 15%; and CBR 97% vs 92% for PRRT/CAPTEM v PRRT respectively. For treatment related adverse events 22/32 CAPTEM patients experienced one Grade 3 event (69%) vs 5/13 (38%, PRRT); 4/32 pts experienced one Grade 4 event (13%) v 1/13 (8%) respectively. Only one patient failed to complete therapy due to toxicity (PRRT/CAPTEM). Conclusions: This initial planned analysis demonstrates similarly high 15 month PFS for CAPTEM/PRRT relative to PRRT alone. OTRR is numerically higher but at the cost of greater toxicity. Longer follow up is required to determine if the activity of PRRT/CAPTEM is sufficient to warrant Phase III evaluation. Clinical trial information: ACTRN12615000909527.

Circulating tumor DNA (ctDNA) heterogeneity as first- and third-line treatment in patients (pts) with metastatic colorectal cancer (mCRC) treated with panitumumab

238

Background: RAS mutations are negative predictors of response to anti-EGFR therapies such as panitumumab in mCRC. Mutations at baseline (BL) and follow-up (FU) during randomized phase 3 studies of first line treatment (1L; study 20050203 [‘203]; panitumumab + fluorouracil, leucovorin and oxaliplatin [FOLFOX4] vs FOLFOX4) were compared with those in third line treatment (3L; study 20100007 [‘0007]; panitumumab + best supportive care [BSC] vs BSC) to assess tumor heterogeneity via ctDNA analysis. Methods: Biomarker analysis was conducted for pts with plasma samples at BL and FU. Samples were analyzed using the Plasma Select-R 63-gene panel (Personal Genome Diagnostics, Inc.), with a limit of detection of 0.1%. Mutations were defined at the amino acid level. The Cox hazard ratio (HR) by sum of RAS mutant allele frequency (MAF) was determined, as were event-free survival (EFS) and best response by RAS mutation status. Results: For all pts with available samples (‘203, n = 120; ‘0007, n = 90), fewer mutations and fewer mutations/gene were observed in the 1L vs 3L setting at BL ( KRAS 2 vs 3 maximum mutations/gene; EGFR 1 vs 4 maximum mutations/gene). In 3L the Cox HR increased continuously with RAS MAF; while this was not found in 1L. In the 1L setting, emergent RAS mutations were not predictive of EFS for FOLFOX4, but were predictive of shorter EFS for panitumumab + FOLFOX4. More panitumumab-treated pts in the 3L setting had detectable RAS mutations emerging from BL to FU (28.6%, 57.1%) vs pts treated in 1L (24.5%, 26.5%). For pts who achieved a partial response, more treated in 1L maintained a higher frequency of wild-type RAS from BL to FU (84.4%, 78.1%) vs pts treated in 3L (95.7%, 43.5%). Conclusions: The overall mutational landscape differs between the 1L vs 3L setting in anti-EGFR–treated mCRC pts. Panitumumab monotherapy in the 3L setting appears to induce greater RAS-specific selective pressure than panitumumab FOLFOX4 combination therapy in 1L, resulting in increased RAS mutations at FU in the 3L setting. The combination of panitumumab + FOLFOX in 1L is associated with delayed emergence of expansion of RAS mutations compared to later line single agent panitumumab.

SPAR - a randomised, placebo-controlled phase II trial of simvastatin in addition to standard chemotherapy and radiation in preoperative treatment for rectal cancer: an AGITG clinical trial

BACKGROUND

Retrospective studies show improved outcomes in colorectal cancer patients if taking statins, including overall survival, pathological response of rectal cancer to preoperative chemoradiotherapy (pCRT), and reduced acute and late toxicities of pelvic radiation. Major tumour regression following pCRT has strong prognostic significance and can be assessed in vivo using MRI-based tumour regression grading (mrTRG) or after surgery using pathological TRG (pathTRG).

METHODS

A double-blind phase 2 trial will randomise 222 patients planned to receive long-course fluoropyrimidine-based pCRT for rectal adenocarcinoma at 18+ sites in New Zealand and Australia. Patients will receive simvastatin 40 mg or placebo daily for 90 days starting 1 week prior to standard pCRT. Pelvic MRI 6 weeks after pCRT will assess mrTRG grading prior to surgery. The primary objective is rates of favourable (grades 1-2) mrTRG following pCRT with simvastatin compared to placebo, considering mrTRG in 4 ordered categories (1, 2, 3, 4-5). Secondary objectives include comparison of: rates of favourable pathTRG in resected tumours; incidence of toxicity; compliance with intended pCRT and trial medication; proportion of patients undergoing surgical resection; cancer outcomes and pathological scores for radiation colitis. Tertiary objectives include: association between mrTRG and pathTRG grouping; inter-observer agreement on mrTRG scoring and pathTRG scoring; studies of T-cell infiltrates in diagnostic biopsies and irradiated resected normal and malignant tissue; and the effect of simvastatin on markers of systemic inflammation (modified Glasgow prognostic score and the neutrophil-lymphocyte ratio). Trial recruitment commenced April 2018.

DISCUSSION

When completed this study will be able to observe meaningful differences in measurable tumour outcome parameters and/or toxicity from simvastatin. A positive result will require a larger RCT to confirm and validate the merit of statins in the preoperative management of rectal cancer. Such a finding could also lead to studies of statins in conjunction with chemoradiation in a range of other malignancies, as well as further exploration of possible mechanisms of action and interaction of statins with both radiation and chemotherapy. The translational substudies undertaken with this trial will provisionally explore some of these possible mechanisms, and the tissue and data can be made available for further investigations.

TRIAL REGISTRATION

ANZ Clinical Trials Register ACTRN12617001087347. (www.anzctr.org.au, registered 26/7/2017) Protocol Version: 1.1 (June 2017).

ALT-GIST: Randomized phase II trial of imatinib alternating with regorafenib versus imatinib alone for the first-line treatment of metastatic gastrointestinal stromal tumor (GIST)

11023

Background: Imatinib (IM) is the standard first-line treatment for advanced GIST and regorafenib (REG) is approved for third line therapy. We studied if an alternating regimen of two tyrosine kinase inhibitors, IM and REG, delays resistance to IM and improves outcomes. Methods: ALT-GIST (NCT02365441) is a randomised non-comparative phase II trial to investigate the efficacy of an alternating regimen (ALT) of 21-25 days of IM 400mg orally daily followed by a 3-7-day gap for washout followed by 21 days of REG 160 mg orally daily and a 7-day gap for washout. The control arm was continuous IM 400mg daily. Delayed recruitment led to revised endpoints of activity and safety. To assess clinical activity, the best objective tumor response (OTR) at 9 months was deemed to be an appropriate endpoint in the revised protocol. Results: Seventy-six eligible patients (ALT 40, IM 36) enrolled from June 2015 to September 2018 were evaluable for the OTR. The patients (pts) were predominately male (n = 51, 67%). Median age was 58 (range, 24-81) in the ALT arm and 65 (range, 35-82) in the IM arm. KIT was mutated in 63, PDGFR in 2, and wildtype in 5 tumors. Relative dose intensity in the ALT arm 102% for IM and 82% for REG and was 93% in the IM arm. Median follow-up time was 19.3 months (range 6.0-40.0).The best responses to the ALT and IM treatments were similar at 9 months, 1 vs 0 pts had complete response, 23 vs 23 partial response, 15 vs 13 stable disease, and the OTR was 60% (95% CI, 45-74%) and 64% (95% CI, 48-78%), respectively. Seven (18%) pts in ALT arm and 10 (28%) in IM arm discontinued treatment due to progressive disease. Seven pts (18%) in the ALT arm stopped protocol therapy due to unacceptable toxicity, and none in the IM arm. Fifteen (38%) pts in the ALT arm and 14 (38%) in the IM arm had serious adverse events, mostly grade 3. Progression free survival (PFS) at 1 year was ALT 0.86 (95%CI:0.69,0.94) and IMI 0.83 (95% CI 0.65-0.92), p logrank = 0.57. Conclusions: There was no meaningful difference in the primary endpoint of OTR and in PFS between the groups in this first analysis of ALT-GIST, and no unexpected safety signals. The study is ongoing and other endpoints will be reported in due course. Clinical trial information: ACTRN12614000950662.

A phase I study of oncolytic immunotherapy of metastatic neuroendocrine tumors using intralesional rose bengal disodium: Cohort 1 results

4102

Background: Metastatic neuroendocrine neoplasms (mNEN’s) originating in the gastrointestinal tract are frequently slow growing yet both symptom and disease control remain important. Treatment options include resection, chemoablation, systemic somatostatin analogues (SSA) or peptide receptor radionuclide therapy (PRRT), but additional options are needed and one such option is hepatic intralesional (IL) rose bengal disodium (PV-10), an oncolytic immunotherapy under development for solid tumours. Methods: This phase 1 study is evaluating the safety, tolerability and reduction of biochemical markers and symptoms resulting from percutaneous administration of PV-10 in 12 subjects with progressive mNEN with hepatic lesions not amenable to resection or other potentially curative therapy. Target lesion(s) must be 1.0 - 3.9 cm in longest diameter. In Cohort 1 (n = 6) subjects receive PV-10 to a single hepatic lesion per treatment cycle, and can receive PV-10 to additional uninjected hepatic lesions ≥6 weeks after prior injection. Cohort 2 (n = 6) subjects may receive injection of multiple lesions per treatment cycle. The primary endpoint is safety. Secondary endpoints include objective response rate (ORR) assessed by contrast enhanced CT and 68Ga-DOTATATE PET, biochemical response (CgA) and patient-reported outcome (EORTC QLQ-C30 and GI.NET21). Results: Cohort 1 has fully enrolled, with 4 of 6 subjects male, median age 65yrs, range 47-72. Primary sites were: small bowel 3, pancreas 2, caecal 1; grade: Gd1 = 5, Gd2 = 1. All patients received prior SSA and PRRT. Median CgA was 645 (range 30-2819). To date 1 subject has received 4 PV-10 treatment cycles, 1 has received 2 cycles, and 4 have received a single cycle. Toxicity has been acceptable, including pain post procedure, carcinoid flare and nausea. LFT’s have remained stable. Overall QOL score was stable for 5 of 6 subjects. ORR in injected lesions is 50% (progression in 1 subject), with overall disease control of 84%. CgA response: 5 stable, 1 progression. One subject with “carcinoid pellagra” had rash resolution. Response follow-up is ongoing and additional efficacy and functional data will be presented. Conclusions: Hepatic IL PV-10 elicited no safety concerns with encouraging evidence of both local and systemic disease control. Enrolment to Cohort 2 is underway. Clinical trial information: NCT02693067.

A pooled analysis of multicenter cohort studies of post-surgery circulating tumor DNA (ctDNA) in early stage colorectal cancer (CRC)

3518

Background: Studies in multiple tumor types have demonstrated the prognostic impact of ctDNA analysis after curative intent surgery. Emerging data suggest that conversion of ctDNA from detectable to undetectable after adjuvant chemotherapy may reflect treatment efficacy. Further review of existing study data could increase the precision of ctDNA guided adjuvant therapy decision making. Methods: We combined individual patient (pt) data from three independent prospective cohort studies that enrolled 485 pts with stage II or III CRC. Clinicians were blinded to ctDNA results. We evaluated pt outcomes over a 5-year follow-up period (median, 47.2 months). Plasma samples were collected 4 to 10 weeks after surgery. Mutations in ctDNA were assayed using Safe-SeqS. Results: ctDNA was detected after surgery in 59 (12%) pts overall (11.0%, 12.5% and 13.8% respectively for samples taken at 4-6, 6-8 and 8-10 weeks; P = 0.740). ctDNA detection was associated with nodal status; 8.7%, 16.7% and 32.4% in N0, N1 and N2 disease (P < 0.001), but remained an independent adverse prognostic factor in multivariable analysis. ctDNA detection was associated with poor overall survival for pts treated (mortality ratio, 3.0; P = 0.026) or not treated with adjuvant chemotherapy (mortality ratio, 5.17; P < 0.001). The median MAF (mutant allele frequency) in pts with detectable ctDNA was 0.046%. For pts not treated with adjuvant chemotherapy, 3 year recurrence free survival (RFS) was 9% in pts with a MAF > 0.046% vs 33% with a MAF ≤ 0.046% (HR, 2.7; P = 0.032). For chemotherapy treated pts, 3 year RFS was 25% in pts with a MAF > 0.046% vs 70% with a MAF ≤ 0.046 (HR, 3.1; P = 0.025). In 90 pts with recurrence, ctDNA had been detected post surgery in 3 of 20 (15%) with locoregional recurrence, 27 of 60 (45%) with distant recurrence and 5 of 10 (50%) with both (P = 0.044). Conclusions: Where samples for ctDNA analysis were collected 4 to 10 weeks post surgery, sampling timing may not significantly impact detection rates. The prognostic significance of ctDNA detection can be further stratified by MAF level, but MAF level may not impact adjuvant treatment benefit. ctDNA analysis is most sensitive for detecting minimal residual disease at distant sites.

Metastasectomy and BRAF mutation: An analysis of survival outcome in metastatic colorectal cancer

3531

Background: Surgical resection of oligometastases improves survival in metastatic colorectal cancer (mCRC). It is unclear whether such benefit is consistently observed for BRAF V600E mutant (MT) and wild type (WT) mCRC. We conducted a retrospective analysis to explore the influence of BRAF mutation status on survival outcomes after metastasectomy. Methods: Data collected from two large prospective population databases in Australia (Treatment of Recurrent and Advanced Colorectal Cancer (TRACC) and South Australian cancer registry). Overall survival (OS) and recurrence free survival (RFS) for BRAF MT and WT mCRC were evaluated by Kaplan-Meier method and compared by log-rank test. Results: 513 patients who had undergone metastasectomy were identified, 6% were BRAF MT. Median age 63. Metastasectomy rate was lower in BRAF MT (13 v 27%). In BRAF WT, 4% underwent resection of metastases (mets) in >1 organ at diagnosis and 5% had 3 or 4 metastasectomies versus none in BRAF MT. Median OS in BRAF MT v WT: 25.7 v 48.5 months (HR 1.95; 1.18-3.22). In a multivariate model adjusting for variables which were significant on univariate analysis, OS differences were not statistically significant. Right primary tumor, intact primary, >1 metastatic sites at diagnosis, non R0 resection, peritoneal mets and synchronous mets were independent predictors of worse OS. Among 364 patients with RFS data there was no difference between BRAF MT and WT (16 v 19 months, p=0.09). Rate of downsizing was higher with triplet chemo than doublet +/- bevacizumab or doublet/EGFR in BRAF WT (50 v 30%) as well as MT (33 v 11%). Conclusions: Median OS was > 2 years in BRAF MT V600E after metastasectomy in this study consistent with an OS benefit. OS did not differ after metastasectomy between BRAF MT and WT in a multivariate model. Presence of BRAF MT should not impact patient selection for metastasectomy.[Table: see text]

Type 2 diabetes as a potential risk marker for early onset colorectal cancer

e15005

Background: Colorectal cancer (CRC) is rising in incidence in young adults. Because they are not included in population screening, and are more likely to present at an advanced stage, there is a need to identify young adults at increased risk for CRC. An association has been reported between type 2 diabetes (T2D) and CRC in the general population. Though lifestyle risk factors may be involved, the early occurrence of CRC in young adults suggests that there may also be a role for inherited predispositions. We therefore investigated whether having a personal and/or first-degree family history of T2D was a potential risk marker for early onset CRC. Methods: The South Australian Young Onset (SAYO) CRC study is an unselected series of young adults with CRC up to age 55. Fifty unrelated young adults (31/50 or 62% female) diagnosed with CRC were recruited to the study. Personal history of T2D was confirmed. Detailed family history of T2D was recorded. 253 patients with clear colonoscopies and no known CRC predisposition served as controls for personal history studies of T2D. Diabetes status was recorded on admission for colonoscopy controls. Associations were explored using a chi-squared statistic. Results: CRC patients ranged in age from 23-54 years (median age 42) and controls from 18-54 (median age 45). Six patients (12%) met the WHO clinical criteria for serrated polyposis, and two (4%) carried a Lynch syndrome mutation. CRC was present in the distal colon in 15/19 males (79%) and 17/31 females (55%) (p = 0.12). A personal history of T2D was confirmed in 12/50 (24%) CRC patients compared with clear colonoscopy controls under 55 years (13/258 or 5% P < 0.001; OR = 5.9; 95%CI 2.5-13.8). T2D was seen in 7/31 or 23% females and 5/19 or 26% males. Young adults with CRC frequently reported at least one first-degree relative with T2D (24/47 or 51%). All patients with personal history of T2D also had first-degree relatives with T2D. A first-degree family history of T2D was observed in 12/27 (44%) CRC patients aged under 45 yrs and 12/20 (60%) of CRC patients aged between 45 and 54 yrs having this characteristic (p = 0.29), and was present in both males and females (10/17 or 58% and 13/30 or 43% respectively; p = 0.37). Conclusions: Though the mechanism remains unclear, given the prevalence of T2D in those aged < 55yrs is 5% in Australia, our observations suggest that there is a striking enrichment for personal and first-degree family history of T2D in young adults with CRC. These features could potentially identify a subset of young adults at increased risk for CRC and in whom early screening might be appropriate.

Phase 1 study evaluating the safety, tolerability, pharmacokinetics (PK), and efficacy of AMG 510, a novel small molecule KRASG12C inhibitor, in advanced solid tumors

3003

Background: The KRASG12C mutation is found in approximately 13% of lung adenocarcinomas and 1–3% of other solid tumors, but there is no approved therapy that targets this mutation. AMG 510 is a novel small molecule that specifically and irreversibly inhibits KRASG12C by locking it in an inactive GDP-bound state. Methods: This phase 1, first-in-human, open-label, multicenter study (NCT03600883) is evaluating the safety, tolerability, PK, and efficacy of AMG 510 in adult patients (pts) with locally-advanced or metastatic KRASG12C mutant solid tumors. The primary endpoint is safety; key secondary endpoints include PK, ORR (assessed every 6 weeks [wks]), DOR, and PFS. Key inclusion criteria: KRASG12C mutation identified through DNA sequencing, measurable or evaluable disease, ECOG PS ≤2, life expectancy >3 months (mo). Key exclusion criteria: active brain metastases, myocardial infarction within 6 mo. A dose exploration will determine the maximum tolerated dose (MTD) or recommended phase 2 dose (RP2D). A dose expansion will enroll pts with NSCLC, CRC, and other advanced solid tumors carrying the KRASG12C mutation. AMG 510 will be given PO until disease progression, intolerance, or withdrawal of consent. Results: 22 pts (8 men, 14 women; median age 55.5 y) were enrolled in the first 3 dose cohorts. Tumor types: 6 NSCLC, 15 CRC, 1 other. Most pts (n=17) had ≥3 prior lines of treatment (tx). Median tx duration was 28 d (range: 8–134). 5 pts reported 10 treatment-related AEs (grade 1, n=9; grade 2, n=1); there were no DLTs. Tumor response was evaluated in 9 pts (4 with ≥2 assessments); 13 pts have not reached their first assessment.1 pt had a PR (NSCLC at wks 6 and 12, tx ongoing), 6 pts had SD (4 CRC and 2 NSCLC; median tx duration 9.7 wks [range: 6.3–19.1], tx ongoing), 2 pts had PD. 20 pts are continuing to receive AMG 510. A second PR (NSCLC at wk 6, tx ongoing) was reported after data cutoff. Conclusions: AMG 510 has been well tolerated at the dose levels tested and has shown antitumor activity when administered as monotherapy to patients with advanced KRAS G12C mutant solid tumors. MTD has not been determined, and enrollment into the dose exploration is ongoing. Clinical trial information: NCT03600883.

Health-related quality of life in the early-access phase IIIb study of trifluridine/tipiracil in pretreated metastatic colorectal cancer (mCRC): Results from PRECONNECT study

638

Background: Pivotal RECOURSE trial assessed efficacy and safety of trifluridine/tipiracil (FTD/TPI) in mCRC patients (pts) without collecting QoL data. Here we describe a preliminary analysis of QoL in mCRC pts treated with FTD/TPI in the ongoing phase 3b PRECONNECT study (NCT03306394). Methods: Eligible pts had histologically mCRC previously treated with available therapies and an ECOG-PS of 0/1. Pts received FTD/TPI (35 mg/m2 twice daily) orally on days 1–5 and 8–12 of each 28-day cycle. ECOG-PS and QoL were assessed at baseline, every 4 weeks on FTD/TPI and at discontinuation. QoL was measured with EORTC QLQ-C30, EQ-5D index and VAS questionnaires. Utility score was based on EQ-5D index and values from Germany, UK and Spain. For QLQ-C30, clinical relevance was assessed using a 10 point threshold. Changes in utility score and VAS were deemed clinically relevant if ≥ 9 and ≥ 7, respectively. Only results where ≥ 10% of the initial cohort completed the questionnaires were assessed, corresponding to 7 cycles of treatment. Results: 464 pts were included at cutoff (1 November 2017). Median FTD/TPI treatment duration was 2.96 months (range 0.4–14.7). Median time to ECOG-PS ≥ 2 was 8.7 months with 74.3% of pts remaining at ECOG-PS 0/1 at discontinuation. At baseline mean QLQ-C30 global health status was 62.75 (SD = 20.50; median 66.67) with values for all scales in line with EuroQoL reference for mCRC (variation < 10 points on function and < 5 on symptom scales). Baseline EQ-5D VAS was 65.55 (SD = 20.11; median 70.00) and utility score 73.11 (SD = 20.71; median 75.27). There was no clinically relevant difference in mean change from baseline at any time point on global health status score nor any of functional or symptom scales. Similar results were obtained for utility score and VAS. QoL was maintained on FTD/TPI in all subgroups based on age and ECOG-PS for all scales except for appetite loss increase at cycle 5 in pts ≥ 65 and in ECOG-PS 0 in whom the score increased by 12.2 and 10.4, respectively. Conclusions: The first prospective data on QoL suggest that mCRC pts can maintain their QoL while on FTD/TPI treatment. Clinical trial information: NCT03306394.

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]

The prognostic impact of consensus molecular subtypes (CMS) and its predictive effects for bevacizumab benefit in metastatic colorectal cancer: molecular analysis of the AGITG MAX clinical trial

BACKGROUND

The consensus molecular subtypes (CMS) is a transcriptome-based classification of colorectal cancer (CRC) initially described in early-stage cohorts, but the associations of CMS with treatment outcomes in the metastatic setting are yet to be established. This study aimed to evaluate the prognostic impact of CMS classification and its predictive effects for bevacizumab benefit in metastatic CRC by correlative analysis of the AGITG MAX trial.

PATIENTS AND METHODS

The MAX trial previously reported improved progression-free survival (PFS) for the addition of bevacizumab (B) to chemotherapy [capecitabine (C)±mitomycin (M)]. Archival primary tumours from 237 patients (50% of trial population) underwent gene expression profiling and classification into CMS groups. CMS groups were correlated to PFS and overall survival (OS). The interaction of CMS with treatment was assessed by proportional hazards model.

RESULTS

The distribution of CMS in MAX were CMS1 18%, CMS2 47%, CMS3 12%, CMS4 23%. CMS1 was the predominant subtype in right-sided primary tumours, while CMS2 was the predominant subtype in left-sided. CMS was prognostic of OS (P = 0.008), with CMS2 associated with the best outcome and CMS1 the worst. CMS remained an independent prognostic factor in a multivariate analysis. There was a significant interaction between CMS and treatment (P-interaction = 0.03), for PFS, with hazard ratios (95% CI) for CB+CBM versus C arms in CMS1, 2, 3 and 4: 0.83 (0.43-1.62), 0.50 (0.33-0.76), 0.31 (0.13-0.75) and 1.24 (0.68-2.25), respectively.

CONCLUSIONS

This exploratory study found that CMS stratified OS outcomes in metastatic CRC regardless of first-line treatment, with prognostic effects of CMS groups distinct from those previously reported in early-stage cohorts. In CMS associations with treatment, CMS2 and possibly CMS3 tumours may preferentially benefit from the addition of bevacizumab to first-line capecitabine-based chemotherapy, compared with other CMS groups. Validation of these findings in additional cohorts is warranted.

CLINICAL TRIAL NUMBER

This is a molecular sub-study of MAX clinical trial (NCT00294359).

Semiclassical Treatment of High-Lying Electronic States of H2. J Phys Chem A 2018;122:8565-8575. [PMID: 30299945 DOI: 10.1021/acs.jpca.8b07878]

We report quantum-mechanical and semiclassical WKB calculations for energies and wave functions of high-lying ²Σ states of H₂⁺ in atomic units. The high-lying states we present lie in an unexplored regime, corresponding asymptotically to H ( n ≤ 146) plus a proton, with R ≤ 120 000 a₀. We compare quantum-mechanical energies, spectroscopic constants, dipole matrix elements, and phases with semiclassical results and demonstrate a high level of agreement. Our quantum-mechanical phases were determined by using Milne's phase-amplitude procedure. We compare our semiclassical energies for low-lying states with those of other researchers.

Semiclassical analysis of jm → j'm' transitions in rotationally inelastic collisions in cell experiments

Recent quantum calculations of rotationally inelastic collisions of NaK (A¹Σ⁺) with He or Ar in a cell experiment are analyzed using semiclassical approximations valid for large quantum numbers. The results suggest a physical interpretation of jm → j'm' transitions based on the vector model and lead to expressions that explicitly involve the initial and final polar angles of the angular momentum of the target molecule. The relation between the polar angle θ and the azimuthal quantum number m links the semiclassical results for the change in polar angle (θ → θ') to quantum results for an m → m' transition. Analytic formulas are derived that relate the location and width of peaks in the final polar angle distribution (PAD) to the K-dependence of the coefficients d_K(j, j'), which are proportional to tensor cross sections σ_K(j → j'). Several special cases are treated that lead to final PADs that are approximately Lorentzian or sinc functions centered at θ' = θ. Another interesting case, "angular momentum reversal," was observed in the calculations for He. This phenomenon, which involves a reversal of the direction of the target's angular momentum, is shown to be associated with oscillatory behavior of the d_K for certain transitions. Finally, several strategies for obtaining the d_K coefficients from experimental data are discussed.

Impact of primary tumor side (TS) on outcomes of once-every-2-weeks (q2w) cetuximab + first-line (1L) FOLFOX or FOLFIRI in patients with RAS wild-type (wt) metastatic colorectal cancer (mCRC) in the phase 2 APEC trial

747

Background: In the RAS wt population of APEC, q2w cetuximab combined with 1L FOLFOX or FOLFIRI achieved a best confirmed overall response rate (BORR), median progression-free survival (PFS), and median overall survival (OS) similar to those reported in prior 1L pivotal studies involving weekly (qw) cetuximab. In this hypothesis-generating subgroup analysis, we evaluated the impact of TS in APEC study patients with RAS wt mCRC. Methods: APEC was a nonrandomized phase 2 trial conducted in the Asia-Pacific region, with BORR as the primary endpoint. Patients with KRAS exon 2 wt tumors received q2w cetuximab + investigator’s choice of FOLFOX or FOLFIRI; subsequent analyses considered patients who were RAS wt ( KRAS/ NRAS, exons 2-4). TS was categorized in evaluable patients with RAS wt tumors (left [L]-sided = splenic flexure, descending colon, sigmoid colon, and rectum; right [R]-sided = appendix, cecum, ascending colon, hepatic flexure, and transverse colon). Results: Among 167 patients with RAS wt mCRC, 159 were evaluable for TS; 130 (81.8%) had L-sided and 29 (18.2%) had R-sided mCRC. Baseline characteristics in the TS subgroups reflected the known differences between L- and R-sided mCRC. Efficacy data for the TS subgroups are summarized in the table. Conclusions: Consistent with prior 1L pivotal studies involving qw cetuximab, a prognostic effect of TS in patients receiving 1L q2w cetuximab was confirmed in APEC. BORR remained ≥50% in patients with R-sided mCRC, in line with prior evidence that use of cetuximab may be appropriate when tumor shrinkage/cytoreduction is the goal. These hypothesis-generating data also raise the possibility of synergy between cetuximab and, in particular, irinotecan for PFS and OS in patients with R-sided tumors, although numbers are small. Clinical trial information: NCT00778830. [Table: see text]

The prognostic role of inflammatory markers in patients with metastatic colorectal cancer treated with bevacizumab

719

Background: Bevacizumab (BEV) with fluoropyrimidine-containing chemotherapy is well-established for patients (pts) with mCRC. There is a need for reproducible, validated, inexpensive and accessible prognostic markers to aid in treatment selection. Pre-treatment levels of systemic inflammatory markers including the neutrophil to lymphocyte ratio (NLR) have been shown retrospectively to be prognostic in many tumors. This study aimed to prospectively evaluate the relationship between NLR and treatment outcomes in previously untreated mCRC pts receiving BEV-based therapy. Methods: ASCENT (NCT01588990) is an open-label, single arm, phase-IV, multi-center study. Pts received 1st-line BEV+XELOX or mFOLFOX6 in phase A (PhA) with planned continuation of BEV+FOLFIRI beyond 1st progression in phase B (PhB). Primary analysis: association of NLR with progression free survival (PFS). Secondary analyses: overall survival (OS) and safety. Sub-study: safety in pts with intact primary in situ (PIS) and resected primary tumor (RPT). Results: 128 pts started PhA; median age 63.5 years (range: 26-84), 70(55%) females, 51(40%) PIS, 71(56%) and 56(44%) were PS 0 and ≥ 1; respectively. 53(41%) pts entered PhB. The median baseline (b) NLR was 3.2 (range: 1.5-20.4) with 32(25%) pts having a baseline level > 5. The hazard ratio (HR) for PFS by NLR > 5 vs ≤5 was 1.4 (95% CI: 0.9-2.2; p = 1.01). Median PFS was 9.2 months (mo; 95% CI: 7.9-10.8) for PhA and 6.7 mo (95% CI: 3.0-8.2) for PhB. HR for OS based on baseline NLR > 5 vs ≤5 was 1.6 (95% CI: 1.0-2.7; p = 0.052). Based on a multivariate model, the 12-month predicted OS probability for pts with PS 0, no metastatic liver disease and ≤ 3 sites of other metastatic disease, was 87% in pts with bNLR ≤ 5 and 79% in pts with bNLR > 5. Median OS was 25 mo (95% CI: 19.2-29.7) for the full analysis set and 14.9 mo for PhB. Treatment related toxicities were numerically and qualitatively consistent with prior experience. There were 4(3%) instances of GI perforation, of which, 3(6%) occurred in the PIS group. Conclusions: Consistent with previous studies, the trend was towards worse PFS and OS in pts with higher bNLR, but the association was not proven. Clinical trial information: NCT01588990.

Outcomes for metastatic colorectal cancer (mCRC) based on microsatellite instability

759

Background: Microsatellite instability (MSI) has been associated with improved survival outcomes in early stage CRC. In stage IV disease, MSI represents only 3-5% of cases and currently the prognostic implications are less clear. There is however evolving evidence that treatment pathways should include anti-PD-1 antibodies given the encouraging results in heavily pre-treated MSI mCRC patients. We undertook an analysis of the South Australian mCRC population based registry to explore the relevance of MSI status in this population based registry. Methods: The registry was analysed to assess patient characteristics and survival outcomes comparing patients with MSI or microsatellite stable (MSS) disease. K-M survival analysis was used to assess OS. Results: 4359 patients are registered on the data base. 598 (14%) patients had been tested for MSI. 62 (10.1%) of these patients had demonstrable MSI. Patient characteristics and outcomes are summarized in the table. There are statistically higher rates of right sided primary, poorly differentiated pathology and BRAF mutation in the MSI group associated with a trend to reduced survival. Chemotherapy and biological therapy received in the MSI v MSS groups was as follows; 5FU 31% v 25%, 5FU/irinotecan 17% v 12%, 5FU/oxaliplatin 52% v 58%, bevacizumab 31% v 42%, anti-EGFR 0 v 4.6%. Conclusions: The patient characteristics of MSI mCRC are in keeping with those previously reported. MSI in this population based mCRC registry is not associated with a favorable outcome as seen in earlier stage disease compared to patients with MSS disease. The trend to poorer outcomes may support routine testing and potentially an alternate treatment pathway, which may include PD-1 inhibitors.[Table: see text]

The Association of FCGR2A and FCGR3A polymorphisms with outcomes in cetuximab treated metastatic colorectal cancer patients: CCTG and AGITG CO.20 trial analysis

633

Background: We previously reported that the Fc-gamma receptor (FCGR) germline polymorphism in the FCGR2A gene (rs1801274; His (H) to Arg (R) substitution) but not FCGR3A (rs396991; Phe (F) to Val (V)) was associated with cetuximab benefit on overall survival (OS) in metastatic colorectal cancer patients (CCTG CO.17 trial). We performed a validation of these results in CO.20, a randomized trial of cetuximab+placebo vs. cetuximab+brivanib for metastatic, chemotherapy refractory, wild type K-RAS colorectal cancer. Methods: After genotyping DNA extracted from whole blood, the polymorphism relationships with OS and progression-free survival (PFS) were assessed using log-rank tests and hazard ratios (HR) from Cox proportional hazard models, adjusting for known prognostic factors. Results: Of 592/725 (82%) K-RAS wild type patients with available DNA and genotyping, those carrying the higher affinity FCGR2A H/H genotype (N = 165; 28%) had improved OS (HR 0.53; 95%CI:0.41-0.68) and PFS (HR 0.65; 95%CI:0.51-0.83) compared to those carrying the lower affinity R/R genotype (N = 128; 22%), corresponding to median absolute benefits of 3.7 (OS) and 3.3 months (PFS). The H/R genotype (N = 299; 50%) had intermediate outcomes. No significant associations were found between FCGR3A genotype and OS or PFS. No interaction between FCGR polymorphisms and treatment arm was observed. Patients carrying the double wild type combination of FCGR2A H/H and FCGR3A F/F genotypes (N = 45; 7.6%) had significantly better outcomes than other patients, particularly those carrying the rare (N = 11; 2%) R/R+ V/V genotype combination, corresponding to median absolute benefits of 12.5 (OS; HR 0.33 95%CI:0.16-0.68) and 4.5 (PFS; HR 0.45 95%CI:0.22-0.92) months. There were no significant associations between FCGR polymorphisms and either any grade of 3/4 toxicity or skin rash. Conclusions: In KRAS-wild type, cetuximab-treated patients, FCGR2A polymorphism was independently replicated to be associated with clinical outcome without affecting toxicity profiles. Additionally, in this large dataset, FCGR3A appears to modulate the relationship between FCGR2A polymorphism and outcome.

Baseline characteristics in the international, open-label, early-access program of trifluridine/tipiracil in previously treated metastatic colorectal cancer (phase IIIb)

761

Background: In the phase 3 RECOURSE trial, trifluridine/tipiracil (FTD/TPI, also known as TAS-102) significantly improved overall and progression-free survival versus placebo in patients (pts) with metastatic colorectal cancer (mCRC) progressing after all available standard therapies (Mayer et al. N Engl J Med 2015;372:1909-19). FTD/TPI is approved after regorafenib in the same setting for management of previously treated mCRC patients. A phase 3b early-access program (EAP) is ongoing to provide access to FTD/TPI for mCRC pts with similar eligibility criteria to assess safety profiles in real-world setting (EudraCT Number: 2016‐002311‐18). First pt was enrolled in Oct 2016. We describe the characteristics of pts included up to 7 March 2017. Methods: Eligible pts had histologically confirmed mCRC previously treated with, or not considered candidates for, available therapies. Other inclusion criteria include Eastern Cooperative Oncology Group performance status (ECOG-PS) 0 or 1. Pts planned to receive FTD/TPI (35 mg/m2 bid) orally on days 1–5 and 8–12 of each 28-day cycle. Results: A total of 298 pts from 7 countries had received at least 1 dose of treatment. Median age was 65 years (range 28–87); 65% were male; 98% were Caucasian (n = 264 out of 269). Among 271 pts, 40% and 60% had respectively ECOG PS 0 and 1 at baseline except 1 pt with PS 2. Primary site of disease was colon (55%, of which 27% right-sided and 61% left-sided); 33% have rectum as primary site; and not specified in 12%,52% had synchronous disease at diagnosis. Median time from initial diagnosis was 37 months (range 6–302) and from first metastasis was 32 months (range 1–180). 59% had RAS mutation (n = 164 out of 279). More than 95% received fluoropyrimidine and/or oxaliplatin and/or irinotecan, while 82%, 39% and 37% received anti-VEGF, anti-EGFR and regorafenib prior to study enroll, respectively. Conclusions: Analysis of the baseline characteristics shows a heavily pretreated mCRC population still seeking additional anti-cancer therapy. Optimal treatment sequencing in 3rd line is not yet established. Preliminary safety and efficacy results are anticipated in 2018. Clinical trial information: 2016-002311-18.

Quality of life at baseline in the international open-label early-access program of trifluridine/tipiracil in previously treated metastatic colorectal cancer (phase IIIb)

803

Background: Pivotal phase 3 RECOURSE trial evaluated efficacy and safety of trifluridine/tipiracil (FTD/TPI, also known TAS-102) in metastatic colorectal cancer (mCRC) without collecting quality of life (QoL) data (Mayer et al. N Engl J Med 2015;372:1909-19). We set up a phase IIIb open-label, early access program to confirm safety and to assess QoL in mCRC in real-world practice (EudraCT Number: 2016‐002311‐18). First patient (pt) was enrolled in Oct 2016; enrolment is ongoing. Methods: Eligible pts had histologically confirmed mCRC previously treated with, or not considered candidates for, available therapies. Other inclusion criteria include Eastern Cooperative Oncology Group performance status (ECOG PS) 0 or 1. Pts planned to receive FTD/TPI (35 mg/m2 bid) orally on days 1–5 and days 8–12 of each 28-day cycle. Pts health-related QoL were measured with the European Organization for Research and Treatment of Cancer Quality of Life (EORTC QLQ-C30) and the EuroQol 5-dimension, 3-level (EQ-5D) questionnaires and visual analogue scale (VAS). For the EORTC QLQ-C30 global health status, EQ-5D utility values and VAS, scores could range to a maximum of 100 representing a better health-related QoL. EORTC QLQ-C30 and EQ-5D were considered non evaluable when responses were missing for one third or at least one of the dimensions, respectively. QoL was measured at baseline, every 4 weeks on treatment, and at treatment discontinuation. Results: A total of 298 pts from 7 countries had received at least 1 dose of treatment as of 7 March 2017. Among 271 patients, 39.5% and 60.1% had respectively ECOG PS 0 and 1 at baseline except 1 pt was enrolled with ECOG PS 2. Out of these 298 pts, 263, 261 and 258 were evaluable at baseline for EORTC QLQ-C30 global health status, EQ-5D utility values and VAS, respectively. These means were 62.4 (standard deviation [SD] 21.3), 73.6 (SD 20.3) and 66.1 (SD 19.1), respectively. Conclusions: Analysis of pt QoL in the real-world practice shows it may be substantially deteriorated in heavily pretreated pts with advanced mCRC in spite of having an ECOG PS of 0/1. Preliminary safety /efficacy and QoL results are expected in summer 2018. Clinical trial information: 2016-002311-18.

Single nucleotide polymorphisms (SNPs) in COL4A2, PPP1R17, and ARHGAPP44 and prognostic value in metastatic colorectal cancer (mCRC)

720

Background: Our previous study has identified COL4A2, PPP1R17 and ARHGAP44 SNPs using whole exome sequencing with potential prognostic significance (Townsend et al. ASCO GI 2017). COL4A2 encodes a subunit of type IV collagen, the C-terminal of which is an inhibitor of angiogenesis. We assessed prognostic impact of these variants in patients from the phase III MAX study (capecitabine +/- bevacizumab (+/- mitomycin C)). An analysis of predictive effect on bevacizumab was also undertaken. Methods: DNA was extracted from archival macrodissected formalin fixed paraffin embedded tumor tissue and genotyped using Agena Bioscience MassARRAY system (AGRF). Univariate association of variant group (WT versus mutation (MT)) with progression free survival (PFS) and overall survival (OS) was assessed using Kaplan-Meier curves and Cox regression models. Logistic regression models were used to assess association with response rate (RR). A cox regression model with treatment, variant status and their interaction investigated if variants were predictive of bevacizumab effect. Results: Of the available 145 of 471 (31%) patients in the MAX study, 25 (17%) had COL4A2 MT, 29 (20%) PPP1R17 MT, 14 (10%) ARHGAP44 MT. Patient demographics were comparable across treatment groups and outcomes similar to whole study population. On univariate analysis median PFS was numerically longer for WT vs MT in all 3 variants, but these differences were not significant (COL4A2 WT 8.4m v MT 6.0m, p=0.09; PPP1R17 WT 7.8m v MT 7.5m, p=0.76; ARHGAP44 WT 8.2m v MT 6.5m, p=0.86). There was also no significant association between variant type and OS. Multivariate analysis for COL4A2 MT v WT showed no significant difference in PFS or OS (HR 1.42; 95% CI 0.91-2.22, p=0.13 and HR 1.33; 95% CI 0.85-2.1, p=0.21). There was no association between treatment response and variant status. Variant status was not predictive of bevazicumab efficacy for treatment response, PFS or OS. Conclusions: There was no significant prognostic or predictive impact of novel gene variants in patients treated with bevacizumab. This may be due to small numbers of MT variants in this study and further studies in larger populations may be useful.

Panitumumab versus cetuximab in patients with wild-type KRAS exon 2 metastatic colorectal cancer who received prior bevacizumab therapy: A combined analysis of individual patient data from ASPECCT and WJOG6510G

745

Background: The ASPECCT (Price T, et al. Eur J Cancer 2016) and WJOG6510G (Sugimoto N, et al. ASCO-GI 2017) trials demonstrated noninferiority of panitumumab (Pmab), compared with cetuximab (Cmab), regarding the overall survival (OS) for chemotherapy-refractory wild-type KRAS exon 2 metastatic colorectal cancer (mCRC). However, the subgroup analyses of both trials revealed a longer survival with Pmab than Cmab in patients who previously received bevacizumab (Bev). We performed a combined analysis of both trials using individual patient data. Methods: In both trials, patients with wild-type KRAS exon 2 mCRC who progressed on or were intolerant to CPT-11- or L-OHP-based chemotherapy were randomized to receive Pmab or Cmab monotherapy (ASPECCT) or in combination with CPT-11 (WJOG). The patient subgroup with prior Bev was eligible for enrollment in this analysis. Results: In the combined data of 374 patients, 185 patients were enrolled in the Pmab arm (ASPECCT, 126; WJOG, 59) and 189 patients in the Cmab arm (ASPECCT, 132; WJOG, 57). The patient characteristics were well-balanced in both arms. Of the 374 patients, 341 (91%) and 369 (99%) had the OS and progression-free survival (PFS) events, respectively. The median OS was 12.8 months in the Pmab arm and 10.1 months in the Cmab arm ( P = 0.0031; the log-rank test stratified by trial). The hazard ratio (HR) for OS was 0.72 (95% confidence interval [CI], 0.58–0.90). The median PFS in the Pmab and Cmab arms were 4.7 and 4.1 months, respectively (P = 0.0207). HR for PFS was 0.79 (95% CI: 0.64–0.97). Response rates in the Pmab and Cmab arms were 23% and 16%, respectively (P = 0.114). Although the incidence of skin toxicities was similar, the infusion reaction was observed more in the Cmab arm (any grade, 1.1% vs 8.6%), whereas hypomagnesemia was noted more in the Pmab arm (48% vs 33%). Conclusions: This combined analysis demonstrated that Pmab significantly prolonged OS and PFS compared with Cmab, raising the potential that Pmab is the more reliable anti-EGFR option for patients with wild-type KRAS exon 2 metastatic colorectal cancer who previously received Bev.

The impact of primary tumour resection and sidedness in patients with synchronous metastatic colorectal cancer (mCRC): Findings from the South Australian Metastatic Colorectal Cancer Registry (SAMCRC)

739

Background: The benefit of primary tumour resection (PTR) in patients with synchronous mCRC is not clear. The influence of tumour location on PTR benefit is also uncertain. Methods: SAMCRC is a population based registry collating data from all patients in South Australia diagnosed with mCRC from February 2006. We examined outcomes according to whether the primary colorectal tumour was excised within 3 months of diagnosis or remained in situ; we also examined whether outcomes were affected by tumour side (right v left). Registry data was included for patients with synchronous metastic adenocarcinoma from colon or rectum. Exclusion criteria included metastasectomy, tumour resection within 7 days or death within 3 months of mCRC diagnosis. Kaplan Meier analysis was used for Survival. Tumour sidedness and PTR were analysed with a multivariate Cox proportional hazards model. Survival was measured from the landmark date (3 months from date of diagnosis). Results: 2575 patients with synchronous mCRC have entered the database, of which 1869 patients were eligible for the PTR analysis. 50.2% (n = 938) underwent PTR. 481 patients (51.3%) of the PTR analysis group had left-sided primary tumours whilst 436 had right sided tumours (46.5%) which was significant (p < 0.001). 63% of the PTR cohort were male (n = 1006). Site and age metastases were included in the multivariate analysis. PTR was associated with improved survival from landmark compared to no resection (15.0 mo vs 11.2 mo, 95% CI 15.0 – 16.3 vs 11.2 – 12.3, p = 0.031). In the entire synchronous mCRC group, left-sided tumours (62.1%) had a longer median survival (17.8 mo vs 10.4 mo, 95% CI 15.7 – 19.5 vs 10.4 – 11.7 p = < 0.001). An interaction test was performed for sidedness and was not significant. Conclusions: PTR was associated was associated with improvement in survival in this large population based registry. This finding did not differ signifcantly between right and left sided tumours. Survival was superior for patients with left sided tumours, in keeping with established data. Criteria for selection of patients with mCRC who benefit from PTR need to be defined.

Rotationally inelastic collisions of excited NaK and NaCs molecules with noble gas and alkali atom perturbers

We report measurements of rate coefficients at T ≈ 600 K for rotationally inelastic collisions of NaK molecules in the 2(A)¹Σ⁺ electronic state with helium, argon, and potassium atom perturbers. Several initial rotational levels J between 14 and 44 were investigated. Collisions involving molecules in low-lying vibrational levels (v = 0, 1, and 2) of the 2(A)¹Σ⁺ state were studied using Fourier-transform spectroscopy. Collisions involving molecules in a higher vibrational level, v = 16, were studied using pump/probe, optical-optical double resonance spectroscopy. In addition, polarization spectroscopy measurements were carried out to study the transfer of orientation in these collisions. Many, but not all, of the measurements were carried out in the "single-collision regime" where more than one collision is unlikely to occur within the lifetime of the excited molecule. The analysis of the experimental data, which is described in detail, includes an estimate of effects of multiple collisions on the reported rate coefficients. The most significant result of these experiments is the observation of a strong propensity for ΔJ = even transitions in collisions involving either helium or argon atoms; the propensity is much stronger for helium than for argon. For the initial rotational levels studied experimentally, almost all initial orientation is preserved in collisions of NaK 2(A)¹Σ⁺ molecules with helium. Roughly between 1/3 and 2/3 of the orientation is preserved in collisions with argon, and almost all orientation is destroyed in collisions with potassium atoms. Complementary measurements on rotationally inelastic collisions of NaCs 2(A)¹Σ⁺ with argon do not show a ΔJ = even propensity. The experimental results are compared with new theoretical calculations of collisions of NaK 2(A)¹Σ⁺ with helium and argon. The calculations are in good agreement with the absolute magnitudes of the experimentally determined rate coefficients and accurately reproduce the very strong propensity for ΔJ = even transitions in helium collisions and the less strong propensity for ΔJ = even transitions in argon collisions. The calculations also show that collisions with helium are less likely to destroy orientation than collisions with argon, in agreement with the experimental results.

Current challenges in optimizing systemic therapy for patients with pancreatic cancer: expert perspectives from the Australasian Gastrointestinal Trials Group (AGITG) with invited international faculty

INTRODUCTION

Despite recent progress, the outlook for most patients with pancreatic cancer remains poor. There is variation in how patients are managed globally due to differing interpretations of the evidence, partly because studies in this disease are challenging to undertake. This article collates the evidence upon which current best practice is based and offers an expert opinion from an international faculty on how latest developments should influence current treatment paradigms. Areas covered: Optimal chemotherapy for first and subsequent lines of therapy; optimal management of locally advanced, non-metastatic cancer including the role of neoadjuvant chemo(radio)therapy, current evidence for adjuvant chemotherapy, major advances in pancreatic cancer genomics and challenges in supportive care particularly relevant to patients with pancreatic cancer. For each section, literature was reviewed by comprehensive search techniques, including clinical trial websites and abstracts from international cancer meetings. Expert commentary: For each section, a commentary is provided. Overall the challenges identified were: difficulties in diagnosing pancreatic cancer early, challenges for performing randomised clinical trials in all stages of the disease, some progress in systemic therapy with new agents and in identifying molecular subtypes that may be clinically relevant and move towards personalized therapy, but still, pancreatic cancer remains a very poor prognosis cancer with significant palliative care needs.

Age as a predictive and prognostic factor for targeted therapy treatment in metastatic chemorefractory colorectal cancer (CRC): An analysis of NCIC CTG CO.17 and CO.20

3555

Background: There is minimal data on the efficacy and improvement of quality of life (QoL) of these targeted therapies, like cetuximab, in elderly CRC patients (≥70yo). We analyzed outcomes from two randomized phase III clinical trials from the Canadian Clinical Trials Group, CO.17 and CO.20. Methods: CO.17 and CO.20 were retrospectively analyzed. CO.17 compared cetuximab (CETUX) with best supportive care (BSC), CO.20 compared CETUX + brivanib (BRIV) with CETUX + placebo. Key eligibility criteria were similar between each trial. Patients were dichotomized by age (≥70yo/ < 70yo) for comparisons. Outcomes included overall survival (OS), progression free survival (PFS), adverse events (AEs), and QoL deterioration. In CO.17, only patients with wild type K-RAS were included in analysis. Multivariate analysis with Cox regression controlled for additional variables. Results: 980 patients were included in this analysis. 257 (26.2%) were ≥70yo at the time of enrollment. In CO.17, OS and PFS were similar between young and elderly patients treated with CETUX (OS 9.7m vs 8.0m, p = 0.45; HR 0.73 95%CI 0.39-1.37). Compared to the BSC arm, elderly patients treated with CETUX had a non-significant increase in OS (8.0m vs 5.1m, p = 0.11). In patients treated with CETUX, grade 3/4 AEs were similar between age groups, however elderly patients had a faster deterioration in global QoL than younger patients (3.6m vs 5.7m p = 0.046). In CO.20, younger patients had longer OS than elderly (9.2m vs 7.6m, p = 0.02; HR 0.81 95% 0.68-0.97, p = 0.02). AEs in the BRIV+CETUX arm were higher in the elderly than young (88% vs 77%, p = 0.03). Both young and elderly treated with BRIV+CETUX had more rapid decreases in global QoL than the CETUX arm. Conclusions: Age was neither prognostic nor predictive of response to targeted therapy in the single agent CO.17 trial. In CO.20, age conferred a worse prognosis. Elderly patients who are eligible for clinical trials may garner similar survival benefits as younger patients with single agent therapy, but may not derive the same improvement in QoL.

Impact of overall severity of adverse events (AEs) on long-term outcomes in metastatic colorectal cancer (mCRC) patients (pts) treated with first line systemic chemotherapy: Findings from 3,971 pts in the ARCAD database

3582

Background: The prognostic importance of the incidence, severity, type and duration of AEs pts experience during chemotherapy varies between tumor types, and the available evidence across the board is often conflicting. Here we investigated the impact of the overall severity of AEs among pts with mCRC receiving first-line oxaliplatin (Oxa)- and/or irinotecan(Iri)-based regimens. Methods: The overall severity of AE data (i.e., max grade (G) of all AEs) were available on 3,971 pts (median age 61; 60% male, 47% ECOG PS 1+; 57% 2+ metastatic sites) enrolled onto 6 1st-line randomized trials. Around 46%, 45%, and 9% of pts had received Oxa-, Iri-, and Oxa+Iri-based regimens, respectively. Pts receiving biologic agents were excluded. Stratified multivariate Cox models were used to assess the associations with overall survival (OS) and progression-free survival (PFS); adjusted hazard ratios (HRadj) and 95% confidence intervals (CIs) are reported. Results: Pts who only received Oxa-based treatment reported the lowest rate of G3+ AEs (p < .0001) compared to pts treated with Iri- or Oxa+Iri-based regimens. Older age, female gender, and PS 1 or 2+ were associated with higher grade AEs (all p < .0001). Considering AEs experienced within 6w after randomization, 10% and 61% of pts experienced G4+ and G2-3 AEs, respectively. G3+ AEs were associated with a shorter OS for both pts receiving Oxa- (HRadj= 1.2, 95% CI, 1.1-1.3, padj < .0001) and Iri-based regimens (HRadj= 1.4, 95% CI, 1.2-1.5, padj < .0001). For the entire treatment course, 19% and 72% of pts experienced G4+ and G2-3 AEs, respectively. For Oxa-based regimens, pts with G3+ AEs had a longer OS (HRadj= 0.86, 95% CI, 0.78-0.94, padj = .0016), whereas G3+ AEs were associated with a shorter OS (HRadj= 1.2, 95% CI, 1.1-1.4, padj = .0004) for pts treated with Iri-based regimens. Similar patterns were seen for PFS. Conclusions: Pts who reported higher grade AEs during initial treatment (≤6w) have significantly worse outcome than those who do not. Further analyses with treatment exposure/detailed dose-AE profile and its impact on survival are warranted.

Clinical outcomes and emergent circulating tumor (ct)DNA RAS mutations and allele fraction for patients with metastatic colorectal cancer (mCRC) treated with panitumumab from the ASPECCT study

3584

Background: ASPECCT was a phase III clinical trial performed in the chemotherapy-refractory third-line mCRC setting (N = 1010). This analysis explores the relationship between circulating levels of mutations and clinical outcomes for panitumumab-treated subjects using univariate and multivariate models that treat total mutational load as a continuous measure. Methods: 238 subjects treated with panitumumab had paired plasma samples at baseline and post-treatment (PT). Samples were analyzed for mutations using the Plasma Select-R™ 63-gene panel (0.1% limit of detection). The fraction of mutant RAS reads was evaluated for association with tumor response (by RECIST) and overall survival using univariate and multivariate Cox proportional hazards models. Results: 52% of the subjects who were RAS wild-type by plasma at baseline never developed a RAS mutation. For those with mutant RAS ctDNA ( KRAS+ NRAS) detected at baseline or PT, there was an overall increase in RAS mutant DNA fraction at PT compared to baseline. By non-parametric analysis, there was no difference in the distribution of baseline mutant RAS fraction between those who achieved stable disease (SD) or those with progression ( P = 0.09). There was also no difference in the increase in mutant RAS fraction on therapy between subjects with SD or progressive disease (PD). In addition, RAS mutation was not required for progression: 48% of subjects with PD had no RAS mutant DNA detected. Conclusions: In this exploratory analysis, baseline plasma mutant RAS fraction is an unreliable predictor of subsequent tumor response. Subjects with objective response or SD may have stable or rising levels of mutant RAS DNA. Subjects without any detectable RAS mutation still experience PD. These findings suggest that detectable plasma ctDNA RAS mutations do not necessarily predict response to panitumumab and should be interpreted with caution. Further work is needed to establish clinically relevant and validated thresholds. Clinical trial information: NCT01001377.

Profiling circulating tumor (ct)DNA mutations after panitumumab treatment in patients with refractory metastatic colorectal cancer (mCRC) from the phase III ASPECCT study

3523

Background: ASPECCT was a clinical trial performed in the chemotherapy-refractory third-line mCRC setting (N = 1010). This biomarker analysis explores the mutational landscape in panitumumab monotherapy subjects. Analysis of plasma ctDNA at baseline and post-treatment (PT) by next-generation sequencing provides a snapshot of the main changes in key genes before and after therapy. Methods: CtDNA collected at baseline and PT was analyzed for mutations using the Plasma Select-R™ 63-gene panel (0.1% limit of detection). Gain or loss of mutation was defined at the amino acid level. Net change is the sum of mutations gained minus the sum of mutations lost. A single individual could have both net gain and/or net loss of mutations within a single gene. Results: Significant tumor clonal diversification was observed during therapy. In 238 subjects with paired plasma samples,29% of subjects had multiple mutations in the same gene at baseline and 41% of subjects had multiple mutations in the same gene PT. At least 10% of subjects demonstrated an on-therapy acquired mutation in at least one of the following genes: APC, EGFR, ALK, HER4, TP53, AR, KRAS, BRAF, PDGFRA, STK11, ESR1, FBXWT, and KIT (ordered by frequency). New mutations were noted both inside and outside the EGFR pathway. Unexpectedly, patients with a large decrease in mutant DNA burden after anti-EGFR treatment were also seen. EGFR pathway genes with significant net gain were: KRAS, EGFR, NRAS, BRAF, MAP2K1, PIK3CA, and AKT1. Non-EGFR pathway mutations gained included: APC, CDK6, SMARCB1, FBXW7, TERT, RB1, CTNNB1, and IDH1. Conclusions: This 63-gene plasma analysis suggests that there are significant dynamic changes in clonal mutational fraction under anti-EGFR selection. Our analysis reveals that increasing global tumor heterogeneity is associated with poorer overall survival. A subset of patients demonstrated an overall decrease in tumor heterogeneity on panitumumab therapy (28%), indicating that under anti-EGFR selective pressure mutational heterogeneity can also decrease. Clinical trial information: NCT01001377.

Cetuximab (Cet) clearance and survival in patients (pts) with metastatic colorectal cancer (mCRC)

3600

Background: Cet, a monoclonal antibody against EGFR, is a standard therapy for RAS wild-type (WT) mCRC. Limited data suggest a correlation between Cet clearance and progression-free survival (PFS). We performed a population pharmacokinetic (pop-pK) analysis of Cet in pts with KRAS WT mCRC who participated in the randomized phase III NCIC CO.20 trial. Methods: Standard Cet doses ± brivanib (Briv) were administered. Intermittent blood samples were obtained, and analyzed by ELISA for Cet. Pop-pK analysis was conducted to estimate Cet clearance. Pts were divided into quartiles according to clearance parameters to evaluate exposure-outcome with overall survival (OS), PFS, response rate (RR), and toxicity. Results: Blood samples were available from 703 pts. Cet clearance was best described as a one-compartment model with a saturable elimination (defined by Vmax and Km). Mean values (± standard deviation) were 5.6 ± 1.4 L for V, 10.5 ± 2.8 mg/h for Vmax, and 403.1 ± 2.0 mg/L for Km. Vmax and Km were significantly associated with OS, but not PFS or RR. Median OS for pts in the highest quartile of Vmax was 7.8 versus (vs.) 11.6 ms for pts in the lowest Vmax quartile (HR 1.12, 95% confidence interval (CI) 1.05-1.20, p< 0.001). In the highest Km quartile, median OS was 11.6 vs. 7.6 ms in the lowest Km quartile (HR 0.89, 95% CI 0.83-0.96, p= 0.001). Pts with the lowest clearance parameters (lowest Vmax and highest Km) had significantly longer OS (11.6 ms) compared to pts with the highest clearance (highest Vmax and lowest Km) (7.6 ms) (HR 0.67, 95% CI 0.53-0.83, p< 0.001). Overall incidences of grade 3/4 toxicity were not associated with Cet clearance. However, pts with the lowest clearance parameters had more frequent grade 3 diarrhea (OR 0.23, p= 0.005). Conclusions: For KRAS WT mCRC, standard Cet dosing is not optimal for all pts. Pts with lower Cet clearance have significantly improved OS and increased likelihood of grade 3 diarrhea. Further studies are needed to identify individual patient factors associated with Cet clearance, and to optimize Cet dosing based on individual pk assessments.

Bevacizumab and its impact on survival for patients receiving subsequent anti-EGFR therapy: Updated results from the SA metastatic CRC registry

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Background: Debate exists as to whether first line bevacizumab effects subsequent sensitivity to anti-EGFR therapy. Authors hypothesize that initial anti-VEGF therapy may induce biological changes that then increase the risk of acquired resistance to subsequent EGFR inhibitors. Methods: A retrospective cohort study was performed to compare the characteristics and survival of patients who were treated with an anti-EGFR therapy 2nd line and beyond by two groups defined by the first line therapy; 1. chemotherapy (chemo) plus bevacizumab (bev) and 2. chemo alone. Survival for this analysis is from the time of commencing first line chemotherapy and secondly from anti-EGFR therapy. Pearson chi test analysis was performed to determine whether receiving first line bev was associated with worse overall survival (OS). Results: 348 mCRC patients who received chemo with or without bev and then an anti-EGFR therapy were studied. Patient characteristics are summarised in the table below. The significant differences between group 1. Vs. 2. were as follows; median age 63.8 years v 67.9 years (p = 0.005), lower use of single agent FU 6.4% v 19.2%, KRAS status not tested (reflecting the practice changes over time) 19.3% v 39.2%, KRAS MT 2% v 4%, and where BRAF MT status was known (11%); BRAF MT rate 23% v 0. Median OS for the 2 groups was 34.2 months, and 28.2 months respectively (p = 0.12) from first line therapy. Median OS for patients who underwent single agent anti-EGFR as subsequent therapy was also not significantly different, 31.1 months group 1 (n = 60) versus 27.7 months group 2 (n = 85), p = 0.52. Results based on commencement of anti-EGFR therapy are under way. Conclusions: Survival was not significantly different between the two groups, and the trend was towards higher OS with chemo plus bev suggesting that in our registry population, bev administration in first line therapy with chemo did not lead to a worse outcome overall for those patients subsequently receiving anti-EGFR therapy, either with chemotherapy or as a single agent. Updated results from commencement of anti-EGFR therapy will give further insights and will be presented at the meeting.

The outcome of patients (pts) with metastatic colorectal cancer (mCRC) based on site of metastases (mets) and the impact of molecular markers and site of primary cancer on metastatic pattern

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Background: Although liver is the commonest site of mets in pts with CRC, pattern of spread is variable and may reflect different biology in different subsets of pts. Methods: This is a retrospective analysis to explore the outcome of pts with mCRC based on their site of mets at diagnosis and to identify tumor characteristics which could predict the site of mets. Pts from 2 Australian databases, BioGrid (BG) and South Australian Cancer Registry (SA), from 01/2006 to 12/2015 were grouped into 5 cohorts; lung only, liver only or any pts with brain, bone or peritoneal mets. Overall survival (OS) for each group was compared with the rest of the sample using Kaplan Meier analysis and the log rank test separately in each dataset. Mantel-Haenszel Chi-squared test was performed in pooled data to assess the association between KRAS, BRAF, Micro satellite instability (MSI), site of primary and site of mets. Results: 5967 pts were included. In both datasets median OS was significantly higher when mets were limited to lung or liver and shorter for those with brain, bone or peritoneal mets. BRAF, KRAS and MSI data were available for 20%, 37% and 21% of the sample. In the pooled analysis BRAF mutation was associated with brain (Relative Risk=5.2) and peritoneal mets (RR=1.8) with lower incidence of lung (RR=0.3) and liver (RR=0.7) limited mets. KRAS mutation was associated with lung only mets(RR=1.4). Left colon tumors were associated with bone (RR=1.6) and lung only mets (RR=2.3) while peritoneal spread was less frequent compared with right colon tumors(RR=0.6). Rectal cancer was strongly associated with brain, bone and lung mets (RR=1.7, 1.7, 2.0). MSI status was not associated with site of mets though liver only mets was less frequent in MSI high tumors. Conclusions: Survival duration with mCRC is related to the site of mets. OS was significantly better when mets were confined to either lung or liver. BRAF mutation and primary rectal cancer were associated with poor prognostic metastatic sites like brain and bone. [Table: see text]

Results of the Quad wild type arm of the AGITG ICECREAM study: A randomised phase II study of cetuximab alone or in combination with irinotecan in patients with refractory metastatic colorectal cancer with no mutations in KRAS, NRAS, BRAF or PIK3CA

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Background: Cetuximab (cet) increases survival in RAS wild-type (WT) metastatic colorectal cancer (mCRC) in first-line and chemorefractory patients (pts). Adding irinotecan (iri) to cet in refractory pts who had progressed on iri increased response and delayed progression in the BOND trial, which was conducted prior to recognition that RAS mutations are predictive of EGFR-inhibitor (EGFR-I) resistance. Subsequent trials in chemorefractory pts used single agent EGFR-I as standard. In the era of biomarker selection, the benefit of continuing iri versus single agent EGFR-I had not been resolved. Methods: ICECREAM is a randomised phase II trial evaluating cet v cet + iri in chemotherapy-refractory mCRC, stratified for KRAS G13D mutation (previously reported) or no mutations in KRAS, NRAS, BRAF and PI3KCA (Quad WT ). EGFR-I naïve, ECOG PS 0-1 pts, progressing within 6 months of iri and refractory (or intolerant) to fluoropyrimidine and oxaliplatin were randomised to cet 400mg/m2 IV loading then 250mg/m2 weekly +/- iri 180mg/m2q2 wks. The primary endpoint was progression-free survival at 6 months (6m PFS); secondary endpoints were response rate (RR), overall survival (OS), toxicity and quality of life (QOL). Results: From Nov 2012 to June 2016, 48 Quad WT pts were recruited: 2 ineligible (not iri-refractory, BRAF mutation) wre not included for analyses and a further 2 not evaluable for response. Characteristics were balanced between cet (n = 21) v cet-iri (n = 25), except for sex (male 62 v 72%) and primary site (left 95 v 68%). 6m PFS rate was 14% v 41%; HR 0.39 (95% CI: 0.20–0.78, p = 0.008). RR was 10% (2 PR) v 36% (1 CR, 8 PR); p = 0.04. Toxicities were higher with cet-iri; at least one grade 3/4 adverse event in 50 v 23%. No differences in global or specific QOL were seen. Conclusions: The AGITG ICECREAM trial confirms a significant synergy for the addition of iri to cet and improved PFS in Quad WT chemorefractory mCRC, echoing data in molecularly unselected pts. Clinical trial information: ACTRN12612000901808.