Activated tumor cell integrin αvß3 cooperates with platelets to promote extravasation and metastasis from the blood stream.

Metastasis is the main cause of death in cancer patients, and understanding mechanisms that control tumor cell dissemination may lead to improved therapy. Tumor cell adhesion receptors contribute to cancer spreading. We noted earlier that tumor cells can expressing the adhesion receptor integrin αvß3 in distinct states of activation, and found that cells which metastasize from the blood stream express it in a constitutively high affinity form. Here, we analyzed steps of the metastatic cascade in vivo and asked, when and how the affinity state of integrin αvß3 confers a critical advantage to cancer spreading. Following tumor cells by real time PCR, non-invasive bioluminescence imaging, intravital microscopy and histology allowed us to identify tumor cell extravasation from the blood stream as a rate-limiting step supported by high affinity αvß3. Successful transendothelial migration depended on cooperation between tumor cells and platelets involving the high affinity tumor cell integrin and release of platelet granules. Thus, this study identifies the high affinity conformer of integrin αvß3 and its interaction with platelets as critical for early steps during hematogenous metastasis and target for prevention of metastatic disease.

Analysis of potential predictive markers of cetuximab benefit in BMS099, a phase III study of cetuximab and first-line taxane/carboplatin in advanced non-small-cell lung cancer.

PURPOSE The anti-epidermal growth factor receptor (EGFR) antibody cetuximab is efficacious in multiple tumor types. Patient selection with markers predictive of benefit may enhance its therapeutic index. This retrospective, correlative analysis of the phase III trial BMS099 of cetuximab in advanced non-small-cell lung cancer (NSCLC) was conducted to identify molecular markers for the selection of patients most likely to benefit from cetuximab. METHODS In BMS099, 676 chemotherapy-naïve patients with stage IIIB (pleural effusion) or stage IV NSCLC of any histology or EGFR expression status were randomly assigned to taxane/carboplatin (T/C) with or without cetuximab. Biomarkers analyzed included K-Ras and EGFR mutations by direct sequencing, EGFR protein expression by immunohistochemistry (IHC), and EGFR gene copy number by fluorescent in situ hybridization (FISH). Relationships between biomarker status and progression-free survival (PFS), overall survival (OS), and overall response rate (ORR) were assessed by log-rank tests per treatment arm for treatment-specific effects and across the total evaluable population. Results Tumor samples were available from 225 randomly assigned patients. K-Ras mutations were found in 17% of evaluable patients (35 of 202 patients), EGFR mutations were found in 10% (17 of 166 patients), EGFR positivity by IHC was found in 89% (131 of 148 patients), and FISH positivity was found in 52% (54 of 104 patients). No significant associations were found between biomarker status and PFS, OS, and ORR in the treatment-specific analyses. CONCLUSION In contrast with colorectal cancer, and within the limitations of the data set, efficacy parameters did not appear to correlate with K-Ras mutation status or with any of the EGFR-related biomarkers evaluated. Additional exploratory analyses are essential to identify predictive markers and to optimize patient selection for cetuximab therapy in NSCLC.

Cetuximab and first-line taxane/carboplatin chemotherapy in advanced non-small-cell lung cancer: results of the randomized multicenter phase III trial BMS099.

PURPOSE To evaluate the efficacy of cetuximab plus taxane/carboplatin (TC) as first-line treatment of advanced non-small-cell lung cancer (NSCLC). PATIENTS AND METHODS This multicenter, open-label, phase III study enrolled 676 chemotherapy-naïve patients with stage IIIB (pleural effusion) or IV NSCLC, without restrictions by histology or epidermal growth factor receptor expression. Patients were randomly assigned to cetuximab/TC or TC. TC consisted of paclitaxel (225 mg/m(2)) or docetaxel (75 mg/m(2)), at the investigator's discretion, and carboplatin (area under the curve = 6) on day 1 every 3 weeks for < or = six cycles; cetuximab (400 mg/m(2) on day 1, 250 mg/m(2) weekly) was administered until progression or unacceptable toxicity. The primary end point was progression-free survival assessed by independent radiologic review committee (PFS-IRRC); overall response rate (ORR), overall survival (OS), quality of life (QoL), and safety were key secondary end points. PFS and ORR assessed by investigators were also evaluated. Results Median PFS-IRRC was 4.40 months with cetuximab/TC versus 4.24 months with TC (hazard ratio [HR] = 0.902; 95% CI, 0.761 to 1.069; P = .236). Median OS was 9.69 months with cetuximab/TC versus 8.38 months with TC (HR = 0.890; 95% CI, 0.754 to 1.051; P = .169). ORR-IRRC was 25.7% with cetuximab/TC versus 17.2% with TC (P = .007). The safety profile of this combination was manageable and consistent with its individual components. CONCLUSION The addition of cetuximab to TC did not significantly improve the primary end point, PFS-IRRC. There was significant improvement in ORR by IRRC. The difference in OS favored cetuximab but did not reach statistical significance.

Dual inhibition of the epidermal growth factor receptor pathway with cetuximab and erlotinib: a phase I study in patients with advanced solid malignancies.

PURPOSE: To determine the optimal dose of the antiepidermal growth factor receptor (EGFR) monoclonal antibody cetuximab that can be safely administered in combination with a standard daily dose of erlotinib in patients with advanced solid malignancies. PATIENTS AND METHODS: Patients with advanced solid malignancies who had failed standard chemotherapies received escalating doses of cetuximab without a loading dose (100, 200, 250 mg/m(2) i.v. weekly) in combination with a fixed dose of erlotinib (150 mg daily orally) until disease progression or unacceptable toxicity. RESULTS: Twenty-two patients were treated, including 14 patients (64%) with non-small cell lung cancer. Twenty patients received combination treatment at the highest dose level for a median of 5.5 weeks (range, 1-31 weeks). One dose-limiting toxicity was observed: grade 3 skin rash. Overall, the most common adverse events (any grade, grade 3/4) were consistent with the safety profiles of the individual drugs: acneform rash (100%, 9%), diarrhea (77%, 5%), and hypomagnesemia (59%, 12%). Seven of 18 evaluable patients (38.9%) had stable disease lasting for a median of 16.6 weeks (range, 6.1-25.1 weeks). CONCLUSION: Dual EGFR inhibition with cetuximab and erlotinib is feasible; the observed toxicities were manageable and consistent with the safety profiles of the individual drugs. The recommended doses for phase II studies are 250 mg/m(2) i.v. weekly for cetuximab and 150 mg daily orally for erlotinib.

Dual inhibition of the epidermal growth factor receptor with cetuximab, an IgG1 monoclonal antibody, and gefitinib, a tyrosine kinase inhibitor, in patients with refractory non-small cell lung cancer (NSCLC): a phase I study.

PURPOSE: To determine the optimal doses of the antiepidermal growth factor receptor (anti-EGFR) monoclonal antibody cetuximab and the EGFR tyrosine kinase inhibitor gefitinib when administered as a combination for patients with advanced/metastatic non-small cell lung cancer (NSCLC) previously treated with platinum-based chemotherapy. PATIENTS AND METHODS: Patients with advanced/metastatic NSCLC treated with prior platinum-based chemotherapy received escalating doses of weekly cetuximab (100, 200, and 250 mg/m(2), IV) and fixed doses of gefitinib (250 mg/d, PO) until disease progression or unacceptable toxicity. Available tumor samples were analyzed for EGFR expression, EGFR gene copy number and mutations, and K-RAS mutations. RESULTS: Thirteen patients were enrolled in three cohorts. Treatment was generally well-tolerated at all doses. One grade 3 headache, observed on the first treatment cycle was initially considered dose-limiting toxicity (DLT); this event was eventually determined to be caused by a brain metastasis, not toxicity. Three cases of grade 3/4 hypomagnesemia and 1 case of grade 3 skin rash occurred in the highest-dose cohort. Grade 1/2 infusion reactions occurred in three patients without requiring treatment discontinuation. Four patients (31%) achieved stable disease, no responses were observed. None of the patients had EGFR mutations or gene amplification in their tumor samples. CONCLUSION: Dual EGFR inhibition with cetuximab and gefitinib is feasible; the combination can be safely administered and may have modest activity in advanced/metastatic NSCLC. Cetuximab 250 mg/m(2) weekly IV and gefitinib 250 mg/d PO is the recommended phase II dose, although the potential for late-onset hypomagnesemia warrants close monitoring of patients receiving this combined dosage.

Randomized phase II study of gemcitabine plus cisplatin or carboplatin [corrected], with or without cetuximab, as first-line therapy for patients with advanced or metastatic non small-cell lung cancer.

PURPOSE: To evaluate the efficacy of cetuximab added to first-line gemcitabine/platinum in chemotherapy-naïve patients with advanced non-small-cell lung cancer (NSCLC). PATIENTS AND METHODS: In this noncomparative, randomized trial, chemotherapy-naïve patients with recurrent/metastatic NSCLC (stage IV or stage IIIB with malignant pleural effusion) were eligible. Patients received cisplatin (75 mg/m2 i.v., every 3 weeks) or carboplatin (area under the concentration-versus-time curve of 5 intravenously [i.v.], every 3 weeks), and gemcitabine (1,250 or 1,000 mg/m2 i.v., days 1 and 8) plus cetuximab (400 mg/m2 i.v. day 1, followed by 250 mg/m2 weekly), in arm A, or chemotherapy alone, in arm B. Response rate was the primary end point; safety, progression-free survival, and overall survival were secondary end points. RESULTS: Sixty-five patients were randomly assigned to arm A and 66 to arm B. Partial responses were observed in 18 patients (27.7%; 95% CI, 17.3 to 40.2) in arm A and 12 (18.2%; 95% CI, 9.8 to 29.6) in arm B. Median progression-free survival was 5.09 months for arm A (95% CI, 4.17 to 5.98) and 4.21 months (95% CI, 3.81 to 5.49) in arm B. Median overall survival was 11.99 months (95% CI, 8.80 to 15.18) and 9.26 months (95% CI, 7.43 to 11.79) in arms A and B, respectively. Overall toxicity was acceptable and consistent with the profiles of the individual agents. CONCLUSION: First-line treatment with cetuximab plus gemcitabine/platinum is well tolerated and can be administered safely in patients with advanced NSCLC. Differences in response rate, progression-free survival, and overall survival suggest that the addition of cetuximab to platinum/gemcitabine may improve clinical outcomes. Larger studies are in progress to address this hypothesis.

Adaptation of energy metabolism in breast cancer brain metastases.

Brain metastases are among the most feared complications in breast cancer, as no therapy exists that prevents or eliminates breast cancer spreading to the brain. New therapeutic strategies depend on specific knowledge of tumor cell properties that allow breast cancer cell growth within the brain tissue. To provide information in this direction, we established a human breast cancer cell model for brain metastasis based on circulating tumor cells from a breast cancer patient and variants of these cells derived from bone or brain lesions in immunodeficient mice. The brain-derived cells showed an increased potential for brain metastasis in vivo and exhibited a unique protein expression profile identified by large-scale proteomic analysis. This protein profile is consistent with either a selection of predisposed cells or bioenergetic adaptation of the tumor cells to the unique energy metabolism of the brain. Increased expression of enzymes involved in glycolysis, tricarboxylic acid cycle, and oxidative phosphorylation pathways suggests that the brain metastatic cells derive energy from glucose oxidation. The cells further showed enhanced activation of the pentose phosphate pathway and the glutathione system, which can minimize production of reactive oxygen species resulting from an enhanced oxidative metabolism. These changes promoted resistance of brain metastatic cells to drugs that affect the cellular redox balance. Importantly, the metabolic alterations are associated with strongly enhanced tumor cell survival and proliferation in the brain microenvironment. Thus, our data support the hypothesis that predisposition or adaptation of the tumor cell energy metabolism is a key element in breast cancer brain metastasis, and raise the possibility of targeting the functional differentiation in breast cancer brain lesions as a novel therapeutic strategy.

Combinatorial antibody libraries from cancer patients yield ligand-mimetic Arg-Gly-Asp-containing immunoglobulins that inhibit breast cancer metastasis.

Combinatorial antibody libraries have the potential to display the entire immunological record of an individual, allowing one to detect and recover any antibody ever made, irrespective of whether it is currently being produced. We have termed this the "fossil record" of an individual's antibody response. To determine whether cancer patients have ever made antibodies with disease-fighting potential, we screened combinatorial antibody libraries from cancer patients for immunoglobulins that can identify metastatic tumor cells. This strategy yielded human antibodies specific for the activated conformation of the adhesion receptor integrin alphavbeta3 that is associated with a metastatic phenotype. In a remarkable example of convergent evolution, two of these antibodies were shown to contain the Arg-Gly-Asp integrin recognition motif of the natural ligand within the third complementarity-determining region of the heavy chain. These antibodies interfered with lung colonization by human breast cancer cells in a mouse model and inhibited existing metastatic disease. Our data imply that, at least at some time, these antibodies were part of a patient's surveillance system against metastatic cells, targeting the activated conformer of integrin alphavbeta3 and disrupting its functions. The ligand-mimetic nature of these antibodies, combined with specificity for a single receptor, is unique in the integrin-ligand repertoire. The convergent evolution of critical sequences in antibodies and other ligands that bind to the same target means that the immune response has sufficient power to find a best chemical solution for the optimization of binding energy, even though antibodies evolve in real time, as compared with billions of years for the natural ligand.