Chemotherapy-refractory Colorectal Cancer Research Articles

Clinical and biomarker results from a phase II trial of combined cabozantinib and durvalumab in patients with chemotherapy-refractory colorectal cancer (CRC): CAMILLA CRC cohort

CAMILLA is a basket trial (NCT03539822) evaluating cabozantinib plus the ICI durvalumab in chemorefractory gastrointestinal cancer. Herein, are the phase II colorectal cohort results. 29 patients were evaluable. 100% had confirmed pMMR/MSS tumors. Primary endpoint was met with ORR of 27.6% (95% CI 12.7-47.2%). Secondary endpoints of 4-month PFS rate was 44.83% (95% CI 26.5-64.3%); and median OS was 9.1 months (95% CI 5.8-20.2). Grade≥3 TRAE occurred in 39%. In post-hoc analysis of patients with RAS wild type tumors, ORR was 50% and median PFS and OS were 6.3 and 21.5 months respectively. Exploratory spatial transcriptomic profiling of pretreatment tumors showed upregulation of VEGF and MET signaling, increased extracellular matrix activity and preexisting anti-tumor immune responses coexisting with immune suppressive features like T cell migration barriers in responders versus non-responders. Cabozantinib plus durvalumab demonstrated anti-tumor activity, manageable toxicity, and have led to the activation of the phase III STELLAR-303 trial.

Fruquintinib versus placebo in patients with refractory metastatic colorectal cancer (FRESCO-2): an international, multicentre, randomised, double-blind, phase 3 study

There is a paucity of effective systemic therapy options for patients with advanced, chemotherapy-refractory colorectal cancer. We aimed to evaluate the efficacy and safety of fruquintinib, a highly selective and potent oral inhibitor of vascular endothelial growth factor receptors (VEGFRs) 1, 2, and 3, in patients with heavily pretreated metastatic colorectal cancer. We conducted an international, randomised, double-blind, placebo-controlled, phase 3 study (FRESCO-2) at 124 hospitals and cancer centres across 14 countries. We included patients aged 18 years or older (≥20 years in Japan) with histologically or cytologically documented metastatic colorectal adenocarcinoma who had received all current standard approved cytotoxic and targeted therapies and progressed on or were intolerant to trifluridine-tipiracil or regorafenib, or both. Eligible patients were randomly assigned (2:1) to receive fruquintinib (5 mg capsule) or matched placebo orally once daily on days 1-21 in 28-day cycles, plus best supportive care. Stratification factors were previous trifluridine-tipiracil or regorafenib, or both, RAS mutation status, and duration of metastatic disease. Patients, investigators, study site personnel, and sponsors, except for selected sponsor pharmacovigilance personnel, were masked to study group assignments. The primary endpoint was overall survival, defined as the time from randomisation to death from any cause. A non-binding futility analysis was done when approximately one-third of the expected overall survival events had occurred. Final analysis occurred after 480 overall survival events. This study is registered with ClinicalTrials.gov, NCT04322539, and EudraCT, 2020-000158-88, and is ongoing but not recruiting. Between Aug 12, 2020, and Dec 2, 2021, 934 patients were assessed for eligibility and 691 were enrolled and randomly assigned to receive fruquintinib (n=461) or placebo (n=230). Patients had received a median of 4 lines (IQR 3-6) of previous systemic therapy for metastatic disease, and 502 (73%) of 691 patients had received more than 3 lines. Median overall survival was 7·4 months (95% CI 6·7-8·2) in the fruquintinib group versus 4·8 months (4·0-5·8) in the placebo group (hazard ratio 0·66, 95% CI 0·55-0·80; p<0·0001). Grade 3 or worse adverse events occurred in 286 (63%) of 456 patients who received fruquintinib and 116 (50%) of 230 who received placebo; the most common grade 3 or worse adverse events in the fruquintinib group included hypertension (n=62 [14%]), asthenia (n=35 [8%]), and hand-foot syndrome (n=29 [6%]). There was one treatment-related death in each group (intestinal perforation in the fruquintinib group and cardiac arrest in the placebo group). Fruquintinib treatment resulted in a significant and clinically meaningful benefit in overall survival compared with placebo in patients with refractory metastatic colorectal cancer. These data support the use of fruquintinib as a global treatment option for patients with refractory metastatic colorectal cancer. Ongoing analysis of the quality of life data will further establish the clinical benefit of fruquintinib in this patient population. HUTCHMED.

Open-label phase 1 study evaluating the tolerability and anti-tumor activity of selinexor and pembrolizumab in colorectal cancer.

e15579 Background: Colorectal cancer (CRC) is the fourth leading cause of cancer-related deaths worldwide and is heterogenous in its molecular features. Checkpoint inhibitors (CPIs) are approved for only about 5% of unresectable or metastatic CRC with MSI-high (MSI-H)/deficient MMR (dMMR); however, they do not benefit the majority of advanced CRC patients. Selinexor is a first-in-class, oral selective inhibitor of nuclear export (SINE) compound with demonstrated activity in cancers with RAS mutations which are found in ̃50% of CRC. This study aims to evaluate the combination of selinexor with pembrolizumab, an anti-PD-L1 CPI, in chemotherapy refractory CRC. Methods: This phase 1/2, open-label study enrolled patients with advanced/metastatic CRC with progression after prior chemotherapy (1-3 lines for KRAS wild-type (wt), 1-2 for KRAS mutant (mut)), initially into a selinexor monotherapy period to evaluate bioavailability/bioequivalence of a new selinexor formulation, followed by a combination therapy where patients were treated with selinexor 80 mg PO QW and pembrolizumab 200 mg IV every 3 weeks. Patients were assessed for anti-tumor activity, safety, and tolerability of the combination therapy. Results: Enrollment in this study has been completed, and 29 patients have received at least 1 dose of combination therapy: median age was 56 years, 19 (65.5%) male, and 15 (51.7%) have RAS mutations. Median number of lines of prior antineoplastic therapies was 2. Median duration of combination treatment is 39 days (range: 1-246 days). Seventeen patients (58.6%) discontinued therapy mostly due to progressive disease, and 18 patients are evaluable for response. Best response was stable disease in 7 patients (6 of them (85.7%) had RAS mut CRC), and progressive disease in 11 patients (8 of them (72.7%) had RAS wt CRC. Median progression free survival (PFS) is 120 days for patients with RAS mut CRC and 41 days for those with RAS wt CRC. Notably, none of the RAS mut had MSI-H/dMMR CRC while one RAS wt with SD had MSI-H/dMMR CRC. The most common treatment-emergent adverse events (total; ≥Grade 3) were nausea (72.4%; 0%), vomiting (41.4%; 0%), decreased appetite (34.5%; 0%), and fatigue (34.5%; 10.3%). Seven patients (24.1%) had at least 1 treatment-emergent serious adverse event. Conclusions: Selinexor in combination with pembrolizumab has demonstrated disease control in patients with chemotherapy refractory advanced/metastatic CRC. Greater anti-tumor activity was observed in patients with RAS mutations despite absence of MSI-H/dMMR. The therapy was well tolerated with no unanticipated adverse events observed. These results warrant further investigation of selinexor in combination with pembrolizumab in CRC, particularly in CRC with RAS mutations. Clinical trial information: NCT04256707.

A phase IIb study of ramucirumab in combination with TAS102 versus TAS102 monotherapy in metastatic, chemotherapy refractory colorectal cancer patients: The RAMTAS trial of the German AIO (KRK-0316).

TPS3617 Background: Patients with metastatic colorectal cancer (mCRC) with progressive disease on/after or who are intolerant to fluoropyrimidines, oxaliplatin, irinotecan, anti-angiogenic and anti-EGFR therapies have limited therapeutic options and a dismal prognosis, with a median survival below 6 months. Recently, Trifluridin/Tipiracil (TAS102) significantly improved survival in patients with refractory mCRC and ramucirumab has been approved in combination with FOLFIRI for the treatment of patients with mCRC after prior FOLFOX/bevacizumab first line therapy. Previous studies on both components provide a strong rationale to conduct a randomized study evaluating the efficacy and safety of ramucirumab in combination with TAS102 in patients with refractory mCRC to improve efficacy and prevent resistance. Methods: This is an interventional, randomized, open label, multicenter, phase IIb study in patients with advanced mCRC. Eligible patients will be randomized 1:1 and receive either ramucirumab and TAS102 (ramucirumab 8 mg/kg on d1+15, q4w and TAS102 35 mg/m² on d1-5 and d8-12, q4w) or TAS102 alone. Primary endpoint is overall survival as assessed by the Kaplan-Meier method, assuming a 6 months survival probability of 70% with ramucirumab in combination with TAS102 and 58% with TAS102 alone. Treatment groups are compared using the log-rank test. A total of 144 patients will be enrolled at 30 sites (1-sided alpha 0.10, power 0.80). Main secondary endpoints are overall response rate, disease control rate, progression free survival and quality of life. In addition, a large comprehensive translational research program will be conducted to identify novel predictive and prognostic biomarkers. The study started in December 2018. By February 2019, a total of 3 patients have been enrolled. Clinical trial information: NCT03520946.

Analysis of a National Programme for Selective Internal Radiation Therapy for Colorectal Cancer Liver Metastases

AimsPatients with chemotherapy-refractory colorectal cancer liver metastases have limited therapeutic options. Selective internal radiation therapy (SIRT) delivers yttrium 90 microspheres as a minimally invasive procedure. This prospective, single-arm, observational, service-evaluation study was part of National Health Service England Commissioning through Evaluation. MethodsPatients eligible for treatment had histologically confirmed carcinoma with liver-only/liver-dominant metastases with clinical progression during or following oxaliplatin-based and irinotecan-based chemotherapy. All patients received SIRT plus standard of care. The primary outcome was overall survival; secondary outcomes included safety, progression-free survival (PFS) and liver-specific PFS (LPFS). ResultsBetween December 2013 and March 2017, 399 patients were treated in 10 centres with a median follow-up of 14.3 months (95% confidence interval 9.2–19.4). The median overall survival was 7.6 months (95% confidence interval 6.9–8.3). The median PFS and LPFS were 3.0 months (95% confidence interval 2.8–3.1) and 3.7 months (95% confidence interval 3.2–4.3), respectively. During the follow-up period, 143 patients experienced an adverse event and 8% of the events were grade 3. ConclusionSurvival estimates from this pragmatic study show clinical outcomes attainable in the National Health Service comparable with previously published data. This study shows the value of a registry-based commissioning model to aid national commissioning decisions for highly specialist cancer treatments.

Regorafenib in antiangiogenic-naive, chemotherapy-refractory advanced colorectal cancer: A phase IIb trial.

782 Background: The oral multikinase inhibitor regorafenib improves overall survival in advanced colorectal cancer (CRC). The aim of this study was to investigate the safety and efficacy of regorafenib in antiangiogenic-naïve patients with chemotherapy-refractory CRC. Methods: In this single-center, single-arm, phase 2b study, patients received regorafenib 160 mg/day for 3 weeks on/1 week off. Tumor response assessed by RECIST 1.1 and tumor metabolic response by [18F] fluorodeoxyglucose positron emission tomography (PET/CT) according to the European Organization for Research and Treatment of Cancer (EORTC) criteria were evaluated at week 8 (W8). PFS rate was defined as the percentage of evaluable patients alive without progression at W8. Safety was assessed until the cut-off date (May 2, 2017). Results: Overall, 59 patients (59.3% male; median age 58.0 yrs) received regorafenib (median dose 148.8 mg/day). The W8 PFS rate was 46.6% (95% CI 33.3% - 60.1%) and median PFS and OS were 3.6 and 7.5 months, respectively. Overall disease control rate (DCR) was 50.8% by RECIST and 62.7% by EORTC criteria (Table). Most common regorafenib-related grade ≥3 AEs were hypertension (35.6%), hand-foot skin reaction (HFSR) (25.4%) and hypophosphatemia (22.0%). One patient discontinued treatment due to drug-related HFSR. Conclusions: The W8 PFS rate and overall DCR support the anti-tumor activity of regorafenib in antiangiogenic-naïve, chemotherapy-refractory advanced CRC. Compared with the previous phase 3 CORRECT and CONCUR trials, the median PFS suggests a better outcome in this population. These data provide the basis for further investigation of regorafenib’s role in earlier treatment lines in metastatic CRC and on the use of PET/CT in tumor response assessment. Clinical trial information: NCT02465502. [Table: see text]

The Development Of RRx-001, A Novel Nitric-Oxide-Mediated Epigenetically Active Anticancer Agent

RRx-001 is a novel NO and hypoxia mediated anticancer agent with epigenetic activity. In the first-in-human, Phase I trial, 5/5 patients who progressed on RRx-001 treatment were resensitized to previously refractory therapy, hinting at a generalized resensitization effect. A randomized open-label multi-part, multi-center phase II trial of RRx-001 versus regorafenib (ROCKET) has commenced to explore the resensitization and/or 'episensitization' potential in irinotecan refractory tumors and its impact on overall survival. Patients with irinotecan-refractory metastatic colorectal cancer with an ECOG PS 0-1 who progressed on oxaliplatin-, and irinotecan-based regimens with or without bevacizumab, cetuximab or panitumumab are randomized 2:1 to receive RRx-001 16.5mg/m2 IV 1x/week or regorafenib 160mg orally 21 of 28 days until progression or unacceptable toxicity followed by treatment with refractory irinotecan-based therapies. To date, 26 patients have been randomized with 18 patients evaluable for resensitization. Post RRx-001 patients demonstrated marked decreases in CEA in 12/13 patients as compared to 5 patients receiving regorafenib who were too systemically unwell to proceed to subsequent treatment. Progression free survival (ongoing) for RRx-001+irinotecan is 4.9 months compared 1.8 months on Regorafenib+irinotecan. Early results in the ROCKET study suggest that RRx-001-mediated resensitization to previously refractory therapies may have a generalized effect, independent of KRAS or p53 status. These early results are intriguing, suggesting improved QOL and overall survival over currently approved therapy in the chemotherapy refractory colorectal cancer.

O3.8 - Early Results: “ROCKET” a phase II Study of RRx-001, a novel triple epigenetic inhibitor, Resensitization to Irinotecan in Colorectal Cancer

ABSTRACT Background: RRx-001 is a novel broad-spectrum anticancer agent that triply inhibits DNA methyltransferases (DNA MTases), Histone Deacetylases (HDAC), and Lysine Demethylases. In the first-in-human, Phase I trial, 5/5 patients who progressed on RRx-001 treatment were resensitized to previously refractory irinotecan therapy, hinting at a generalized resensitization effect. A randomized open-label multi-part, multi-center phase II trial of RRx-001 versus regorafenib (ROCKET) is underway to explore the resensitization and/or ‘episensitization’ potential in irinotecan refractory tumors and its impact on overall survival. Methods: Patients with irinotecan-refractory metastatic colorectal cancer with an ECOG PS 0–1 who progressed on oxaliplatin-, and irinotecan-based regimens with or without bevacizumab, cetuximab or panitumumab are randomized 2:1 to receive RRx-001 16.5 mg/m2 IV 1x/week or regorafenib 160 mg orally 21 of 28 days until progression or unacceptable toxicity followed by treatment with refractory irinotecan-based therapies. Results: To date, 23 patients have been randomized with 10 patients evaluable for resensitization. Post RRx-001 patients demonstrated marked decreases in CEA in all 6 patients as compared to 4 patients receiving regorafenib who were too systemically unwell to proceed to subsequent treatment. Progression free survival (ongoing) for RRx-001 + irinotecan is 5.9 months compared 0.92 months on Regorafenib + irinotecan. Combined Disease Control Rate (SD + PR) for the combination of RRx-001 and reintroduction of Irinotecan based therapy is currently 100%, whereas no patients to date randomized to the regorafenib arm have been able to start irinotecan based therapy secondary to decreasing performance status. Conclusions: Early results in the ROCKET study suggest that RRx-001-mediated resensitization to previously refractory therapies may have a generalized effect, independent of KRAS or p53 status. These early results are intriguing and may be a major advancement in epigenetic therapy. RRx-001 is a novel pan-epigenetic inhibitor that may potentially offer improved QOL and overall survival over currently approved therapy in the chemotherapy refractory colorectal cancer.

Selective transarterial radioembolisation of unresectable liver-dominant colorectal cancer refractory to chemotherapy.

The target lesion response (according to the Choi criteria), safety and survival following selective or superselective transarterial radioembolisation using yttrium-90-resin microspheres ((90)Y-RE) were evaluated in patients with unresectable, chemotherapy-refractory colorectal cancer liver metastases (mCRC). A prospective case series evaluated 52 consecutive patients with mCRC who were treated at a single centre following a median of 2 lines of chemotherapy. Nearly half (46.2 %) of the 52 patients had a prior resection of the liver. At baseline, mCRC was limited to the liver (in 56.9 %), liver plus extra-hepatic metastases (23.5 %) or liver plus lung micro-nodules (19.6 %). Disease control rates of target lesions (partial response plus stable disease) at 3 and 6 months post-(90)Y-RE were 59 and 29 %, respectively. Target lesions were sufficiently downsized in two patients for hepatic resection and in one patient for radiofrequency ablation. Median Kaplan-Meier survival was 11.0 months (95 % confidence interval: 8.0-14.0 months) overall and 12.0 months in liver-only disease (±lung micro-nodules). Determinants of prolonged survival were response at 3 months (P = 0.046), ≤5 liver nodules (P = 0.004), single-liver-lobe involvement (P = 0.037), tumour-to-whole liver ratio <25 % (P = 0.021) and absence of extrahepatic metastases (P = 0.045). Adverse events possibly related to the nontarget distribution of (90)Y-RE were grade 1 (90)Y-RE-induced liver disease (n = 1), grade 2 and 3 gastric ulcers (n = 2). These results confirm the effectiveness and safety of selective (90)Y-RE in patients with chemotherapy-refractory mCRC, showing (90)Y-RE's potential as a bridging therapy to subsequent resection even in this end-stage population.

PIK3CA, BRAF, and PTEN Status and Benefit from Cetuximab in the Treatment of Advanced Colorectal Cancer—Results from NCIC CTG/AGITG CO.17

Cetuximab improves survival in patients with K-ras wild-type advanced colorectal cancer. We examined the predictive and prognostic significance of additional biomarkers in this setting, in particular BRAF, PIK3CA, and PTEN. Available colorectal tumor samples were analyzed from the CO.17 study. BRAF mutations were identified in tumor-derived DNA by direct sequencing and PIK3CA mutations were identified using a high-resolution melting screen with confirmation by sequencing. PTEN expression by immunohistochemistry (IHC) was performed on tissue microarrays. For each biomarker, prognostic and predictive effects were examined using a Cox model with tests for treatment-biomarker interaction. A total of 572 patients with pretreated colorectal cancer were randomly assigned to receive cetuximab or best supportive care (BSC). Of 401 patients assessed for BRAF status, 13 (3.2%) had mutations. Of 407 patients assessed for PIK3CA status, 61 (15%) had mutations. Of 205 patients assessed for PTEN, 148 (72%) were negative for IHC expression. None of BRAF, PIK3CA, or PTEN was prognostic for overall or progression-free survival in the BSC arm. None was predictive of benefit from cetuximab, either in the whole study population or the K-ras wild-type subset. In the K-ras wild-type subgroup, the overall survival adjusted HR according to BRAF mutation status was 1.39 (interaction P = 0.69), PIK3CA mutation status HR = 0.79 (interaction P = 0.63), and PTEN expression HR = 0.75 (interaction P = 0.61). In chemotherapy-refractory colorectal cancer, neither PIK3CA mutation status nor PTEN expression were prognostic, nor were they predictive of benefit from cetuximab. Evaluation of predictive significance of BRAF mutations requires a larger sample size.

Epiregulin gene expression as a biomarker of benefit from cetuximab in the treatment of advanced colorectal cancer

Background:Anti-EGFR antibody, cetuximab, improves overall survival (OS) in K-ras wild-type chemotherapy–refractory colorectal cancer. Epidermal growth factor receptor ligand epiregulin (EREG) gene expression may further predict cetuximab benefit.Methods:Tumour samples from a phase III clinical trial of cetuximab plus best supportive care (BSC) vs BSC alone (CO.17) were analysed for EREG mRNA gene expression. Predictive effects of high vs low EREG on OS and progression-free survival (PFS) were examined for treatment–biomarker interaction.Results:Both EREG and K-ras status were ascertained in 385 (193 cetuximab, 192 BSC) tumour samples. Within the high EREG and K-ras wild-type status (‘co-biomarker')-positive group (n=139, 36%), median PFS was 5.4 vs 1.9 months (hazard ratio (HR) 0.31; P<0.0001), and median OS was 9.8 vs 5.1 months (HR 0.43; P<0.001) for cetuximab vs BSC, respectively. In the rest (n=246, 64%), PFS (HR 0.82; P=0.12) and OS (HR 0.90; P=0.45) were not significantly different. Test for treatment interaction showed a larger cetuximab effect on OS (HR 0.52; P=0.007) and PFS (HR 0.49; P=0.001) in the co-biomarker-positive group.Conclusion:In pre-treated K-ras wild-type status colorectal cancer, patients with high EREG gene expression appear to benefit more from cetuximab therapy compared with low expression. Epiregulin as a selective biomarker requires further evaluation.

Insights into therapeutic resistance from whole-genome analyses of circulating tumor DNA

The selection and expansion of tumor cells with de novo genetic alterations in specific genes has been described as a mechanism of resistance to targeted therapy. Unfortunately, in the metastatic setting it is often not possible to examine the multiple lesions present in an individual to determine the presence and mechanism of acquired resistance during therapy. Circulating tumor DNA (ctDNA) can be used to analyze the genomic characteristics of tumors in a non-invasive manner [1]. We have previously reported that tumor-specific chromosomal changes can be detected in plasma from patients through integrated whole-genome analyses of cell-free DNA [1]. We have now applied whole-genome sequencing to analyze plasma ctDNA from a patient with chemotherapy-refractory colorectal cancer that had become resistant to EGFR-blockade with cetuximab. A total of 630 Gb of sequence data were obtained, corresponding to 145x sequence coverage of cell-free genomic DNA, and analyzed to identify sequence and structural alterations. These and other analyses revealed emergence of a Q61H mutation in KRAS as well as focal high-level (>9 fold) amplification and rearrangement of the MET locus that were not detected in pre-treatment tumor samples (Figure ​(Figure1).1). Alterations in these genes have been reported in tumors with secondary resistance to EGFR-directed therapy and are consistent with clinical progression [2-5]. In addition to its role in resistance to targeted therapy, MET amplification has been shown to confer sensitivity to the tyrosine kinase inhibitor crizotinib and other inhibitors [6, 7], and may provide a new therapeutic target in patients with resistance to EGFR blockade. These results describe the first whole-genome analysis of ctDNA to identify genetic alterations associated with mechanisms of resistance to a targeted therapy. Our analyses suggest that genome-wide analyses of ctDNA can be used for discovery of tumor-specific alterations in the in the context of disease monitoring, detection of molecular resistance, and identification of new therapeutic targets. Figure 1 Identification of MET amplification through analyses of plasma DNA

Pemetrexed and Gemcitabine for Chemotherapy Refractory Colorectal Cancer—Results of a Phase II and Translational Research Study

Introduction: We investigated the safety and efficacy of pemetrexed with gemcitabine in heavily pre-treated, chemotherapy refractory, KRAS mutated colorectal cancer (mCRC) and the prognostic value of quantitative levels of cell free DNA (cfDNA) in plasma. Methods: Inclusion criteria comprised; histopathologically verified, KRAS mutant, chemotherapy resistant mCRC, adequate organ function and performance status. Patients received pemetrexed (initially 500 mg/m2 q3w) + gemcitabine (1250 mg/m2 days 1 and 8) until progression or unacceptable toxicity. RECIST version 1.1, NCI-CTCAE version 4.0 and Kaplan-Meier statistics were used for endpoint evaluation. Cell free DNA was quantified from pre-treatment EDTA plasma-samples by an in-house qPCR. Results: Forty patients were included. The median number of cycles was 3 (range 0 - 12). Thirty-six percent obtained disease stabilisation, but no objective response was observed. Median PFS and OS were 2.8 (range 2.1 - 4.0) and 5.4 (range 4.3 - 7.0) months, respectively. Adverse events caused immediate discontinuation of treatment or delay of the next cycle and consequently discontinuation in 5 patients. Translational research revealed a shorter PFS and OS with increasing levels of cfDNA. The median PFS in patients with cfDNA levels above the 75 percentile was 2 months compared to 4 months in the remaining patients, HR 3.23 (1.05 - 9.89), p = 0.0008. The median OS was 3 and 6 months, respectively, HR 2.9 (95%CI 0.98 - 8.34). Cox regression analysis confirmed that cfDNA remained a significantly independent prognostic factor for both PFS and OS. Conclusion: Pemetrexed and gemcitabine did not prove sufficient benefit and unacceptable toxicity was observed. The potential value of cfDNA should be investigated further.

P-0245 Vegf Serum Level after Chemoembolization With Drug-Eluting Beads (Debiri) in Patients With Liver Metastases of Chemotherapy Refractory Colorectal Cancer

ABSTRACT Introduction Transcatheter arterial chemoembolization (TACE) with Irinotecan loaded drug eluting beads has shown activity in colorectal liver metastases. Among the factors potentially interfering with its effectiveness is a hypothetical nonangiogenic reaction due to ischemia. In this study we evaluated the changes in VEGF serum levels in patients treated with TACE. Methods Patients with predominant and life threatening liver metastases from CRC which were refractory to all drugs approved for metastasized CRC and documented tumor progression during or shortly after the last chemotherapy, were prospectively treated with Irinotecan loaded drug eluting beads with a size of 100-300 µm. All Patients gave written informed consent. Therapy was applied by a temporary catheter placed in the liver arteries. Usually each lobe of the liver was treated two times with an interval of 4 weeks, according to the recommended DEBIRI treatment algorithm. Each treatment of one liver lobe was performed with 1 vial of the 100-300 µm DC-Beads loaded with 100 mg Irinotecan. Blood samples to measure the VEGF serum levels were taken before TACE and at day 7, 14 and 21 after first treatment (Test-Kit: Human VEGF-A Platinum ELISA, Bender MedSystems). Results Complete blood samples to evaluate the VEGF-A-Levels were taken from 15 Patients ( 12 male/ 3 female; median age 61) from 2/11 to 2/12. 66% (10/15) of patients had an increase of the VEGF-Level with a median of 107, 37%, 33 % (5/15) of patient had a decrease of the VEGF-Level with a median of - 38, 94%. Conclusion These first findings show different behavior of the serum VEGF level after the TACE with Irinotecan loaded Drug eluting Beads, suggesting that the occlusion of blood vessels and subsequent ischemia induces neo-angiogenesis due to these growth factors in 66% of Patients and a subset of 33% with a decrease of VEGF Levels. Updated results concerning correlation of changes of the VEGF-Level with tumor necrosis, response rate or time to progression will be presented. These preliminary results could implicate that antiangiogenic drugs might be effective as an additive therapy to chemoembolization in a subset of patients.

BRAF, PIK3CA, and PTEN status and benefit from cetuximab (CET) in the treatment of advanced colorectal cancer (CRC): Results from NCIC CTG/AGITG CO.17.

3515 Background: CET, a monoclonal antibody targeting the epidermal growth factor receptor, improves overall survival (OS) and progression free survival (PFS) in patients (pts) with KRAS wild-type (WT) chemotherapy refractory CRC. BRAF and PIK3CA mutation status, and PTEN expression levels may further predict benefit from CET therapy. Methods: Available colorectal tumour samples were analyzed from a phase III trial of CET plus best supportive care (BSC) vs BSC alone (NEJM 2007; 357(20)). BRAF and PIK3CA mutations (MUT) identified in tumour-derived DNA using a high resolution melting analysis to identify amplicons with mutations were confirmed by sequencing. PTEN expression by immunohistochemistry (IHC) was performed on tissue microarrays constructed from available tumour blocks. For each biomarker, prognostic (treatment independent) effects were assessed in patients on the BSC alone arm. Predictive effects (benefit from CET) on OS and PFS among all patients and those in the KRAS wild-type subset were examined using a Cox model with tests for treatment-biomarker interaction, adjusting for covariates. Results: Of 401 pts assessed for BRAF status (70% of CO17 population), 13(3%) had mutations. Of 407 pts assessed for PIK3CA status (71% of CO17 population), 61(15%) had mutations. Of 205 pts assessed for PTEN (36% of CO17 population), 148(72%) were negative for IHC expression. No biomarker was prognostic for OS or PFS, and none were predictive of benefit from CET, either in the whole study population or the KRAS WT subset. Conclusions: In chemotherapy-refractory CRC, neither PIK3CA mutation status nor PTEN expression were predictive of benefit from CET therapy. BRAF mutations are uncommon in this setting. Larger sample sizes would be required to determine if BRAF status is predictive for CET benefit. [Table: see text]

A randomized phase II study of two doses of vorinostat in combination with 5-FU/LV in patients with refractory colorectal cancer

Vorinostat is synergistic with 5-FU in vitro and in vivo models. A combination of these two agents was associated with clinical activity in 5-FU refractory colorectal cancer patients in a phase I clinical trial, therefore warranting the conduct of this prospective phase II study. Patients with refractory metastatic colorectal cancer were randomized in a two-stage design to receive vorinostat at 800 or 1,400 mg/day once a day × 3, every 2 weeks. 5-FU, preceded by leucovorin, was administered as a bolus followed by a 46-h infusion on days 2 and 3 of vorinostat. A pre-specified 2-month progression-free survival (PFS) rate of 27/43 patients per arm was needed to deem an arm interesting for further investigation. The high-dose vorinostat arm did not reach the needed efficacy endpoint at completion of the first stage, with only 8 out of 15 patients being alive and progression free at 2 months. The low-dose vorinostat arm proceeded to accrue 43 patients with a 2-month PFS rate of 53% (23 out 43), including one partial response. The median PFS and overall survival on the low-dose arm were 2.4 and 6.5 months, respectively. Both treatment arms were well tolerated. No differences were noted in the pharmacokinetics of vorinostat at the 800- or 1,400-mg dose-levels, suggesting bioavailability saturation. While the addition of vorinostat to 5-FU resulted in 1 partial response and in some disease stabilizations, the limited activity does not warrant the unselected use of this combination in chemotherapy-refractory colorectal cancer.

Early change in tumor size from waterfall plot analysis and RECIST response as predictor of overall survival (OS) in advanced, chemotherapy-refractory colorectal cancer (ACRC): NCIC CTG/AGITG CO.17 study.

3602 Background: The CO.17 trial demonstrated that the addition of cetuximab monotherapy (C) to best supportive care (BSC) improves OS and progression-free survival (PFS) in patients (pts) with ACRC. We compared tumour measurement as a continuous variable and visualized by waterfall plot vs. categorized as response based on RECIST as potential early predictors of OS benefit. Methods: Of the 572 randomized, 216 pts on C and 142 on BSC had tumor assessment at baseline and 8 weeks and are included in this analysis. Response at 8 weeks was assessed using standard RECIST criteria and categorised as partial response, stable disease or progressive disease. Continuous tumour size measurement was also assessed using waterfall plot, The absolute difference in logarithm transformed sum of the longest tumor diameters (LSLD) between 8 weeks and baseline were calculated for the entire group and the KRAS wild-type (WT) and mutant (MUT) subgroups and correlated with OS in a multivariate analysis including difference in LSLD, RECIST response and other prognostic factors as covariates. Results: The increase of tumor size (cm) from baseline of pts treated by C was significantly smaller than those that received BSC (mean difference in LSLD 0.02 vs. 0.23; p < 0.0001), and this remained significant after adjusting for baseline prognostic factors (p<0.0001). In a multivariate analysis of pts treated by C, difference in LSLD was significantly associated with OS (HR 14.84, per ln(cm) of increase, 95% CI 4.31 to 51.08; p<0.0001), whilst RECIST defined response was not. Results were similar for WT pts: HR 14.30 per ln(cm) of increase in LSLD, 95% CI 1.32 to 96.5; p=0.03. For MUT pts, neither change in LSLD nor RECIST response was associated with OS. Conclusions: Change of tumor size at 8 weeks following commencement of C using a waterfall plot analysis was a better predictor of OS than standard RECIST categories. This may be a better early signal of treatment efficacy for molecular targeted therapies in ACRC.

Association of KRAS p.G13D Mutation With Outcome in Patients With Chemotherapy-Refractory Metastatic Colorectal Cancer Treated With Cetuximab

Patients with metastatic colorectal cancer who have KRAS codon 12- or KRAS codon 13-mutated tumors are presently excluded from treatment with the anti-epidermal growth factor receptor monoclonal antibody cetuximab. To test the hypothesis that KRAS codon 13 mutations are associated with a better outcome after treatment with cetuximab than observed with other KRAS mutations. We studied the association between KRAS mutation status (p.G13D vs other KRAS mutations) and response and survival in a pooled data set of 579 patients with chemotherapy-refractory colorectal cancer treated with cetuximab between 2001 and 2008. Patients were included in the CO.17, BOND, MABEL, EMR202600, EVEREST, BABEL, or SALVAGE clinical trials or received off-study treatment. Univariate and multivariate analyses, adjusting for possible prognostic factors and data set, were performed. The effect of the different mutations was studied in vitro by constructing isogenic cell lines with wild-type KRAS, p.G12V, or p.G13D mutant alleles and treating them with cetuximab. The main efficacy end point was overall survival. Secondary efficacy end points were response rate and progression-free survival. In comparison with patients with other KRAS-mutated tumors, patients with p.G13D-mutated tumors (n = 32) treated with cetuximab had longer overall survival (median, 7.6 [95% confidence interval {CI}, 5.7-20.5] months vs 5.7 [95% CI, 4.9-6.8] months; adjusted hazard ratio [HR], 0.50; 95% CI, 0.31-0.81; P = .005) and longer progression-free survival (median, 4.0 [95% CI, 1.9-6.2] months vs 1.9 [95% CI, 1.8-2.8] months; adjusted HR, 0.51; 95% CI, 0.32-0.81; P = .004). There was a significant interaction between KRAS mutation status (p.G13D vs other KRAS mutations) and overall survival benefit with cetuximab treatment (adjusted HR, 0.30; 95% CI, 0.14-0.67; P = .003). In vitro and mouse model analysis showed that although p.G12V-mutated colorectal cells were insensitive to cetuximab, p.G13D-mutated cells were sensitive, as were KRAS wild-type cells. In this analysis, use of cetuximab was associated with longer overall and progression-free survival among patients with chemotherapy-refractory colorectal cancer with p.G13D-mutated tumors than with other KRAS-mutated tumors. Evaluation of cetuximab therapy in these tumors in prospective randomized trials may be warranted.

Successful long-term management of a patient with late-stage metastatic colorectal cancer treated with panitumumab

Recent approval and introduction into clinical practice of epidermal growth factor receptor inhibitors such as the chimeric monoclonal antibody cetuximab and the fully human monoclonal antibody panitumumab have provided new treatment options for chemotherapy-refractory patients. Here, we report a case of a 47-year-old man with metastatic, chemotherapy-refractory colorectal cancer who achieved long-term partial remission during panitumumab therapy. A 41-year-old male patient presented with a 24-hour history of abdominal pain and fever. A computed tomography (CT) scan revealed a voluminous and perforated abscess with a suspected tumour lesion in the sigmoid colon. The patient underwent sigmoidectomy and was diagnosed with a poorly differentiated necrotic carcinoma of the sigmoid colon with invasion in 13 of 19 tested lymph nodes. A colonoscopy revealed multiple tubular adenomas and a positron emission tomography CT scan showed multiple and bilateral hyperfixating lumbar-aortic lymph nodes leading to a final tumour classification of T4N2M1. Carcinoembryonic antigen (CEA) was elevated. The patient achieved a partial response following six cycles of FOLFIRI (irinotecan, 5-fluorouracil, leucovorin), then progressed and was enrolled in a trial where he received treatment with FOLFOX4 (oxaliplatin, leucovorin and 5-fluorouracil) with or without a vascular endothelial growth factor inhibitor (PTK787/ZK 222584 [valatinib]). Eight months later he progressed again and was included in a panitumumab (6mg/kg every 2 weeks) monotherapy trial. A partial response was noted after 8 weeks of therapy along with a rapid CEA reduction and decrease in lymph node size. The patient is continuing panitumumab treatment and is still in partial remission after 65 months' treatment. He has non-mutated KRAS and no human-anti-human antibodies have been detected. During treatment the patient has on occasion experienced grade 1-2 diarrhoea as well as folliculitis and acne-like rash up to grade 3 in severity. Cutaneous toxicity was managed with a combination dose interruption/reduction and the use of topical agents. No eye or nail toxicities occurred. This case shows that long-term responses are possible during panitumumab therapy and that this agent may be an effective long-term treatment option for selected patients with metastatic colorectal cancer. The associated skin toxicities can be successfully managed.

Health-Related Quality of Life in Patients With Advanced Colorectal Cancer Treated With Cetuximab: Overall and KRAS-Specific Results of the NCIC CTG and AGITG CO.17 Trial

National Cancer Institute of Canada Clinical Trials Group CO.17 demonstrated the antiepidermal growth factor receptor (anti-EGFR) monoclonal antibody cetuximab improves overall and progression-free survival in patients with advanced, chemotherapy-refractory colorectal cancer (CRC), particularly in patients with wild-type KRAS tumors. This article reports the health-related quality-of-life (HRQL) outcomes from CO.17. Patients (N = 572) with pretreated EGFR-detectable advanced CRC were randomly assigned to cetuximab and best supportive care (BSC) or to BSC alone. HRQL primary end points assessed by the EORTC QLQ-C30 were physical function (PF) and global health status (GHS); mean changes from baseline to 8 and 16 weeks were assessed. Post hoc analysis by KRAS mutation status was performed. Questionnaire compliance was 94% at baseline, but it declined differentially (67% v 47% for cetuximab v BSC at 16 weeks). PF change scores were -3.9 for cetuximab and -8.6 for BSC (P = .046) at 8 weeks and were -5.9 and -12.5 for cetuximab and BSC, respectively, (P = .027) at 16 weeks. GHS change scores were -0.5 and -7.1 (P = .008) at 8 weeks and were -3.6 and -15.2 (P = .008) at 16 weeks for cetuximab and BSC, respectively. In patients who had tumors with wild-type KRAS status, cetuximab resulted in less PF deterioration at 8 weeks (-0.7 v -7.2; P = .11) and 16 weeks (-3.4 v -13.8; P = .008) compared with BSC. Patients with wild-type status who received cetuximab experienced improved GHS at 8 weeks, whereas patients who received BSC alone deteriorated (3.2 v -7.7; P = .002). Cetuximab preserved GHS at 16 weeks (-0.2 v -18.1; P < .001). No significant differences were noted between study arms for patients with mutated KRAS tumors. Cetuximab offers important HRQL and survival benefits for pretreated patients with advanced, wild-type KRAS CRC.