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

Targeted therapy in non-small-cell lung cancer--is it becoming a reality?

Treatment outcomes in advanced or metastatic non-small-cell lung cancer (NSCLC) remain unsatisfactory, with low long-term survival rates. Palliative chemotherapy offers a median survival not exceeding 1 year. To date, various combinations of cytotoxic drugs have not improved treatment results beyond what has been observed with platinum doublets. By contrast, molecular targeted drugs may block important pathways that drive cancer progression and achieve long-term disease control. Conflicting results have demonstrated marginal benefit with EGFR inhibitors, anti-EGFR monoclonal antibodies and antiangiogenic strategies in unselected populations of patients with advanced NSCLC. However, patients with an EGFR mutation are likely to respond to agents that target this gene. Novel targeted therapies that interfere with insulin-like growth factor 1 receptor, or the EML4-ALK fusion protein have shown promising activity. Aberrations in other key signaling pathways and molecules, such as RAS/RAF/MEK, PI3K/AKT/mTOR, or MET kinase, have been identified as crucial targets, especially in resistant patients. Novel drugs aimed at these abnormalities are already in the clinic. This Review outlines the current state-of-the-art research for targeted therapy in NSCLC.

A pilot study of volume measurement as a method of tumor response evaluation to aid biomarker development

PURPOSE

Tissue biomarker discovery is potentially limited by conventional tumor measurement techniques, which have an uncertain ability to accurately distinguish sensitive and resistant tumors. Semiautomated volumetric measurement of computed tomography imaging has the potential to more accurately capture tumor growth dynamics, allowing for more exact separation of sensitive and resistant tumors and a more accurate comparison of tissue characteristics.

EXPERIMENTAL DESIGN

Forty-eight patients with early stage non-small cell lung cancer and clinical characteristics of sensitivity to gefitinib were studied. High-resolution computed tomography was done at baseline and after 3 weeks of gefitinib. Tumors were then resected and molecularly profiled. Unidimensional and volumetric measurements were done using a semiautomated algorithm. Measurement changes were evaluated for their ability to differentiate tumors with and without sensitizing mutations.

RESULTS

Forty-four percent of tumors had epidermal growth factor receptor-sensitizing mutations. Receiver operating characteristic curve analysis showed that volumetric measurement had a higher area under the curve than unidimensional measurement for identifying tumors harboring sensitizing mutations (P = 0.009). Tumor volume decrease of >24.9% was the imaging criteria best able to classify tumors with and without sensitizing mutations (sensitivity, 90%; specificity, 89%).

CONCLUSIONS

Volumetric tumor measurement was better than unidimensional tumor measurement at distinguishing tumors based on presence or absence of a sensitizing mutation. Use of volume-based response assessment for the development of tissue biomarkers could reduce contamination between sensitive and resistant tumor populations, improving our ability to identify meaningful predictors of sensitivity.

Shifting the paradigm for maintenance therapy in advanced non-small-cell lung cancer

The standard of care in metastatic non-small-cell lung cancer (NSCLC) is to treat patients with a platinum doublet for 4 to 6 cycles and to offer second-line therapy upon progression. Maintenance therapy in NSCLC is defined as a therapeutic agent which is administered after first-line chemotherapy is complete, but before the disease progresses. While maintenance therapy is not yet universally accepted as a therapeutic approach, emerging data have demonstrated its potential to improve progression-free survival and overall survival in a clinically significant way. In this article a concise recent review of data related to the role of maintenance therapy in patients with advanced NSCLC is provided, complementing previous information in the field. It is recommended that NSCLC patients are offered maintenance therapy after first-line therapy is complete.

Fc-engineered EGF-R antibodies mediate improved antibody-dependent cellular cytotoxicity (ADCC) against KRAS-mutated tumor cells

Oncogenic mutations of the KRAS gene have emerged as a common mechanism of resistance against epidermal growth factor receptor (EGF-R)-directed tumor therapy. Mutated KRAS leads to ligand-independent activation of signaling pathways downstream of EGF-R. Thereby, direct effector mechanisms of EGF-R antibodies, such as blockade of ligand binding and inhibition of signaling, are bypassed. Thus, a humanized variant of the approved EGF-R antibody Cetuximab inhibited growth of wild-type KRAS-expressing A431 cells, but did not inhibit KRAS-mutated A549 tumor cells. We then investigated whether killing of tumor cells harboring mutated KRAS can be improved by enhancing antibody-dependent cellular cytotoxicity (ADCC). Protein- and glyco-engineering of antibodies' Fc region are established technologies to enhance ADCC by increasing antibodies' affinity to activating Fcgamma receptors. Thus, EGF-R antibody variants with increased affinity for the natural killer (NK) cell-expressed FcgammaRIIIa (CD16) were generated and analyzed. These variants triggered significantly enhanced mononuclear cell (MNC)-mediated killing of KRAS-mutated tumor cells compared to wild-type antibodies. Additionally, cells transfected with mutated KRAS were killed as effectively by ADCC as vector-transfected control cells. Together, these data demonstrate that KRAS mutations are not sufficient to render tumor cells resistant to ADCC. Consequently Fc-engineered EGF-R antibodies may prove effective against KRAS-mutated tumors, which are not susceptible to signaling inhibition by EGF-R antibodies.

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.