Hans Prenen

Addition of Aflibercept to Fluorouracil, Leucovorin, and Irinotecan Improves Survival in a Phase III Randomized Trial in Patients With Metastatic Colorectal Cancer Previously Treated With an Oxaliplatin-Based Regimen

PURPOSE Treatment for metastatic colorectal cancer (mCRC) commonly involves a fluoropyrimidine-based chemotherapy regimen such as infusional fluorouracil, leucovorin, and irinotecan (FOLFIRI) or fluorouracil, leucovorin, and oxaliplatin, often combined with bevacizumab or an epidermal growth factor receptor monoclonal antibody. We studied the effect of adding the novel antiangiogenic agent aflibercept (also known as ziv-aflibercept in the United States) to FOLFIRI in patients with mCRC previously treated with oxaliplatin, including patients who received prior bevacizumab. PATIENTS AND METHODS Patients were randomly assigned to receive aflibercept (4 mg/kg intravenously; 612 patients) or placebo (614 patients) every 2 weeks in combination with FOLFIRI. Treatment was administered until disease progression or unacceptable toxicity. The primary end point was overall survival. RESULTS Adding aflibercept to FOLFIRI significantly improved overall survival relative to placebo plus FOLFIRI (hazard ratio [HR], 0.817; 95.34% CI, 0.713 to 0.937; P = .0032) with median survival times of 13.50 versus 12.06 months, respectively. Aflibercept also significantly improved progression-free survival (PFS; HR, 0.758; 95% CI, 0.661 to 0.869; P < .0001), with median PFS times of 6.90 versus 4.67 months, respectively. The effects on overall survival and PFS exhibited a consistent trend across prespecified subgroup analyses, including bevacizumab pretreated patients. Response rate was 19.8% (95% CI, 16.4% to 23.2%) with aflibercept plus FOLFIRI compared with 11.1% (95% CI, 8.5% to 13.8%) with placebo plus FOLFIRI (P = .0001). Adverse effects reported with aflibercept combined with FOLFIRI included the characteristic anti-vascular endothelial growth factor effects and also reflected an increased incidence of some chemotherapy-related toxicities. CONCLUSION Aflibercept in combination with FOLFIRI conferred a statistically significant survival benefit over FOLFIRI combined with placebo in patients with mCRC previously treated with oxaliplatin.

Randomized Trial of TAS-102 for Refractory Metastatic Colorectal Cancer

BACKGROUND Early clinical trials conducted primarily in Japan have shown that TAS-102, an oral agent that combines trifluridine and tipiracil hydrochloride, was effective in the treatment of refractory colorectal cancer. We conducted a phase 3 trial to further assess the efficacy and safety of TAS-102 in a global population of such patients. METHODS In this double-blind study, we randomly assigned 800 patients, in a 2:1 ratio, to receive TAS-102 or placebo. The primary end point was overall survival. RESULTS The median overall survival improved from 5.3 months with placebo to 7.1 months with TAS-102, and the hazard ratio for death in the TAS-102 group versus the placebo group was 0.68 (95% confidence interval [CI], 0.58 to 0.81; P<0.001). The most frequently observed clinically significant adverse events associated with TAS-102 were neutropenia, which occurred in 38% of those treated, and leukopenia, which occurred in 21%; 4% of the patients who received TAS-102 had febrile neutropenia, and one death related to TAS-102 was reported. The median time to worsening performance status (a change in Eastern Cooperative Oncology Group performance status [on a scale of 0 to 5, with 0 indicating no symptoms and higher numbers indicating increasing degrees of disability] from 0 or 1 to 2 or more) was 5.7 months with TAS-102 versus 4.0 months with placebo (hazard ratio, 0.66; 95% CI, 0.56 to 0.78; P<0.001). CONCLUSIONS In patients with refractory colorectal cancer, TAS-102, as compared with placebo, was associated with a significant improvement in overall survival. (Funded by Taiho Oncology-Taiho Pharmaceutical; RECOURSE ClinicalTrials.gov number, NCT01607957.).

PIK3CA mutations are not a major determinant of resistance to the epidermal growth factor receptor inhibitor cetuximab in metastatic colorectal cancer.

Purpose: It has been reported that activating KRAS mutations negatively affect response to anti–epidermal growth factor receptor (EGFR) monoclonal antibodies in metastatic colorectal cancer. The mutation status of signaling molecules downstream of the EGFR target is thus crucial to predict clinical benefit to EGFR-targeted therapies. Other mechanisms of resistance to EGFR inhibitors could involve activating mutations of the other main EGFR effector pathway, i.e., the PI3K/PTEN/AKT pathway. Experimental Design: We analyzed the PIK3CA and KRAS mutation status in a large group (n = 200) of chemorefractory metastatic colorectal cancers treated with cetuximab (Erbitux) in monotherapy or in combination with irinotecan, and correlated the mutation status with outcome. Results: Twenty-three (12%) of the 200 samples carried 1 of the PIK3CA mutations included in our assay. We found no correlation between the presence of a PIK3CA mutation and impaired response to cetuximab. Conclusions: Our findings do not provide any evidence for a strong role of PIK3CA mutations as a single marker in determining response to cetuximab in chemorefractory metastatic colorectal cancer.

Efficacy of the kinase inhibitor SU11248 against gastrointestinal stromal tumor mutants refractory to imatinib mesylate.

Purpose: The majority of gastrointestinal stromal tumors harbor mutations in the receptor tyrosine kinases KIT or platelet-derived growth factor receptor A (PDGFRA), and respond to treatment with the tyrosine kinase inhibitor imatinib. Some tumors, however, show primary resistance to imatinib treatment, and most others become resistant during treatment. The most common mechanism of imatinib resistance involves specific mutations in the kinase domains of KIT or PDGFRA. We tested the activity of SU11248, an orally active small-molecule tyrosine kinase inhibitor, to inhibit important imatinib-resistant KIT and PDGFRA mutants. Experimental Design: Primary imatinib-resistant tumor cells and cell lines expressing clinically identified imatinib-resistant KIT-V654A, KIT-T670I, or PDGFRA-D842V mutant isoforms were evaluated for sensitivity to SU11248 by Western immunoblotting and proliferation assays. Three patients with the KIT-V654A mutation were treated with SU11248. Results: Based on ex vivo assays, SU11248 potently inhibits KIT kinase activity of V654A and T670I mutants and suppresses proliferation of the cells expressing these mutations. Sensitivity of KIT-V654A and KIT-T670I mutants to SU11248 was confirmed using cell lines expressing these mutants. In contrast, SU11248 did not potently inhibit the PDGFRA-D842V mutant. In agreement with these results, two of the three imatinib-resistant patients with the KIT-V654A mutation responded to SU11248 treatment. Conclusions: These studies suggest that SU11248 may be a useful therapeutic agent to treat gastrointestinal stromal tumors harboring the imatinib-resistant KIT-V654A or KIT-T670I mutations, but it has no effect on the activity of the PDGFRA-D842V mutant. Specific kinase inhibitors should be designed to inhibit the constitutive activating PDGFRA mutation at codon 842.

Association of enzyme and transporter genotypes with the pharmacokinetics of imatinib

Our objective was to explore the relationships between imatinib pharmacokinetics and 9 allelic variants in 7 genes coding for adenosine triphosphate‐binding cassette transporters (ABCB1 and ABCG2) and enzymes (cytochrome P450 [CYP] 2C9, CYP2C19, CYP2D6, CYP3A4, and CYP3A5) of putative relevance for imatinib.

MET is required for the recruitment of anti-tumoural neutrophils

Mutations or amplification of the MET proto-oncogene are involved in the pathogenesis of several tumours, which rely on the constitutive engagement of this pathway for their growth and survival. However, MET is expressed not only by cancer cells but also by tumour-associated stromal cells, although its precise role in this compartment is not well characterized. Here we show that MET is required for neutrophil chemoattraction and cytotoxicity in response to its ligand hepatocyte growth factor (HGF). Met deletion in mouse neutrophils enhances tumour growth and metastasis. This phenotype correlates with reduced neutrophil infiltration to both the primary tumour and metastatic sites. Similarly, Met is necessary for neutrophil transudation during colitis, skin rash or peritonitis. Mechanistically, Met is induced by tumour-derived tumour necrosis factor (TNF)-α or other inflammatory stimuli in both mouse and human neutrophils. This induction is instrumental for neutrophil transmigration across an activated endothelium and for inducible nitric oxide synthase production upon HGF stimulation. Consequently, HGF/MET-dependent nitric oxide release by neutrophils promotes cancer cell killing, which abates tumour growth and metastasis. After systemic administration of a MET kinase inhibitor, we prove that the therapeutic benefit of MET targeting in cancer cells is partly countered by the pro-tumoural effect arising from MET blockade in neutrophils. Our work identifies an unprecedented role of MET in neutrophils, suggests a potential ‘Achilles’ heel’ of MET-targeted therapies in cancer, and supports the rationale for evaluating anti-MET drugs in certain inflammatory diseases.

Activity of Dasatinib, a Dual SRC/ABL Kinase Inhibitor, and IPI-504, a Heat Shock Protein 90 Inhibitor, against Gastrointestinal Stromal Tumor–Associated PDGFRAD842V Mutation

Purpose: Activating mutations in platelet-derived growth factor receptor-α (PDGFRA) have been reported in ∼5% to 10% of patients with gastrointestinal stromal tumors (GIST). Imatinib efficiently inhibits the juxtamembrane PDGFRA mutations, whereas many tyrosine kinase domain activation loop PDGFRA mutations confer primary resistance to imatinib. In this study, we compared the efficacy of second-line tyrosine kinase inhibitors such as dasatinib, sorafenib, and nilotinib against two GIST-related PDGFRA mutants, PDGFRAD842V and PDGFRAΔDIM842-844. In addition, we sought to investigate the inhibitory effect of the heat shock protein 90 inhibitor, IPI-504, on these mutants. Experimental Design: Primary imatinib-resistant tumor cells and cell lines expressing imatinib-resistant PDGFRAD842V or imatinib-sensitive PDGFRAΔDIM842-844 mutants were treated with different concentrations of dasatinib, sorafenib, nilotinib, and IPI-504. The effect of treatment on proliferation, survival, and signaling was determined. Results: All inhibitors tested exhibited a high efficacy toward the PDGFRAΔDIM842-844 mutant. In contrast, ex vivo and in vitro assays revealed that only dasatinib potently inhibited the PDGFRAD842V isoform with an IC50 value of 62 nmol/L. Sorafenib and nilotinib were significantly less efficacious against this mutation, inhibiting the PDGFRA kinase activity at >1,000 and >5,000 nmol/L, and suppressing the proliferation of the cells expressing the PDGFRAD842V mutant with an IC50 value of 239 and 1,310 nmol/L, respectively. IPI-504 treatment potently inhibited PDGFRA kinase activity by inducing the degradation of PDGFRAD842V and PDGFRAΔDIM842-844 at 256 and 182 nmol/L, respectively. Conclusions: Treatment with dasatinib or the heat shock protein 90 inhibitor IPI-504 may provide a therapeutic alternative for GIST patients whose tumors carry the imatinib-resistant PDGFRAD842V mutant isoform.

Lessons From the Adjuvant Bevacizumab Trial on Colon Cancer: What Next?

Eric Van Cutsem, University Hospital Gasthuisberg/Leuven, Katholieke Universiteit Leuven, Leuven, Belgium Diether Lambrechts, Vesalius Research Center, Vlaams Instituut voor Biotechnologie; Katholieke Universiteit Leuven, Leuven, Belgium Hans Prenen, University Hospital Gasthuisberg/Leuven, Katholieke Universiteit Leuven, Leuven, Belgium Rakesh K. Jain, Massachusetts General Hospital and Harvard Medical School, Boston, MA Peter Carmeliet, Vesalius Research Center, Vlaams Instituut voor Biotechnologie; Katholieke Universiteit Leuven, Leuven, Belgium

Cellular uptake of the tyrosine kinase inhibitors imatinib and AMN107 in gastrointestinal stromal tumor cell lines.

Imatinib and AMN107 are protein tyrosine kinase inhibitors which reduce KIT autophosphorylation with similar potency. This report describes the cellular uptake of these compounds in two human gastrointestinal stromal tumor (GIST)-derived cell lines (GIST882 and GIST GDG1), which both express constitutively activated KIT. In GIST882 and GIST GDG1 cell lines, HPLC analysis revealed AMN107 intracellular concentrations to be 7- and 10-fold greater than those of imatinib. These data indicate either increased cellular uptake or decreased cellular efflux of AMN107 when compared to imatinib in GIST cell lines. The finding suggests that AMN107 might be less susceptible to transport-driven imatinib resistance. The stable and increased exposure of GIST cells to a highly active AMN107 agent could be important in the treatment of imatinib-resistant GIST patients in whom resistance has developed as a result of changes in cellular transport mechanisms for which AMN107 is not a substrate.

Macrophage Metabolism Controls Tumor Blood Vessel Morphogenesis and Metastasis

Hypoxic tumor-associated macrophages (TAMs) acquire angiogenic and immunosuppressive properties. Yet it remains unknown if metabolic changes influence these functions. Here, we argue that hypoxic TAMs strongly upregulate the expression of REDD1, a negative regulator of mTOR. REDD1-mediated mTOR inhibition hinders glycolysis in TAMs and curtails their excessive angiogenic response, with consequent formation of abnormal blood vessels. Accordingly, REDD1 deficiency in TAMs leads to the formation of smoothly aligned, pericyte-covered, functional vessels, which prevents vessel leakiness, hypoxia, and metastases. Mechanistically, highly glycolytic REDD1-deficient TAMs outcompete endothelial cells for glucose usage that thwarts vascular hyperactivation and promotes the formation of quiescent vascular junctions. Tuning down glycolysis in REDD1 knockout TAMs re-establishes abnormal angiogenesis and metastases. On this basis, we prove that the anti-tumor effect of mTOR inhibitors is partly countered by the deleterious outcome of these drugs on TAMs. Our data provide a functional link between TAM metabolism and tumor angiogenesis.