The evolving role of targeted therapy in early-stage and locally advanced non-small cell lung cancer

Many of the leading developments in management of non-small cell lung cancer (NSCLC) have been provided by the integration of specific targeted therapies either in combination with a backbone of standard chemotherapy or as a single agent. Agents that inhibit a specific pathway, such as that triggered by the activity of the epidermal growth factor receptor, or a regulatory process like angiogenesis, have made it possible to markedly increase response rates and extend survival, sometimes dramatically, along with a favorable therapeutic index. However, these novel therapies have established clinical benefit thus for only in the setting of incurable, advanced NSCLC. The value of these strategies in not only extending survival but potentially improving the cure rate when added to, or substituting for, conventional chemotherapy in the setting of early-stage resectable NSCLC or locally advanced NSCLC remains to be determined. A wide range of clinical trials for these settings have been pursued, with several pivotal studies still ongoing, and will be reviewed for their potential to redefine our current standards of care for potentially curable NSCLC through the integration of targeted therapies.

The optimal chemotherapy for stage III non-small cell lung cancer patients

Nearly one third of non-small cell lung cancer (NSCLC) patients at diagnosis have stage III disease. Concurrent chemoradiation has emerged as the standard of care for patients with unresectable stage III NSCLC. Meta-analyses of studies comparing concurrent with sequential therapy showed that there was a relative improvement of about 20% with concurrent therapy over sequential therapy in these patients and that concurrent chemoradiation is more toxic than the sequential approach, particularly with regard to esophagitis. The incidence of pneumonitis is not significantly higher with concurrent therapy. All the phase 3 trials comparing concurrent with sequential therapy included cisplatin-based therapy. In addition, patients enrolled in these studies were required to have good performance status and some studies mandated limited weight loss. Some patients are also treated with lower doses of chemotherapy, particularly carboplatin and paclitaxel, concurrently with radiation followed by full-dose chemotherapy. Randomized studies have failed to show benefit of induction or consolidation chemotherapy. For patients who have a poor performance status or significant weight loss, a sequential approach of chemotherapy followed by radiation may be appropriate. Ongoing clinical trials are evaluating the utility of integrating some of the newer agents such as pemetrexed and cetuximab into the treatment plan for stage III patients.

Phase II study of pemetrexed and cisplatin, with chest radiotherapy followed by docetaxel in patients with stage III non-small cell lung cancer

BACKGROUND

Pemetrexed has emerged as one of the most active agents for the treatment of patients with advanced non-small cell lung cancer (NSCLC). We conducted a phase II study to assess the efficacy and feasibility of integrating pemetrexed in a concurrent therapy plan for patients with stage III NSCLC.

METHODS

Patients with stage III NSCLC with performance status 0 to 1, adequate organ function including pulmonary function, and V20 less than 40% were eligible. Patients were treated with cisplatin 75 mg/m² (first five patients 60 mg/m²) and pemetrexed 500 mg/m² every 21 days for three cycles with chest radiotherapy to 66 Gy. Patients then received three cycles of docetaxel 75 mg/m² every 21 days. Tumors were analyzed for Excision Repair Cross Complementation Group 1 and thymidylate synthase.

RESULTS

Patient characteristics (N = 28) were median age, 60; males, 68%; stage IIIB, 64%; and squamous cell, 43%. Twenty-four patients (86%) completed all three cycles of cisplatin/pemetrexed. Of the 24 patients eligible for docetaxel, 21 (87%) received it. Grade 3/4 toxicities were neutropenia (39%), febrile neutropenia (14%), esophagitis (14%), and pneumonitis (4%). Median survival was 34 months, and 1-year survival was 66%. Survival was not significantly different in squamous and other histology patients. Tumor analysis in 16 patients showed that moderate/strong expression of thymidylate synthase was significantly associated with progression-free survival and overall survival.

CONCLUSION

Integrating pemetrexed in a concurrent therapy regimen for patients with stage III NSCLC is feasible and was associated with a median survival of 34 months.

Lung cancer: New biological insights and recent therapeutic advances

Approximately 1.6 million new cases of lung cancer are diagnosed each year throughout the world. In many countries, the mortality related to lung cancer continues to rise. The outcomes for patients with all stages of lung cancer have improved in recent years. The use of systemic therapy in conjunction with local therapy has led to improved cure rates in both resectable and unresectable patient groups. For patients with advanced stage disease, modest but real improvements in overall survival and quality of life have been achieved with systemic chemotherapy. A major focus of research has been the development of molecularly targeted agents and the identification of biomarkers for patient selection. Patients with non-small cell lung cancer with mutations in the epidermal growth factor receptor (EGFR) tyrosine kinase domain achieve response rates of greater than 70% and superior progression-free survival when treated with an EGFR tyrosine kinase inhibitor compared with standard chemotherapy. This has now emerged as the preferred therapeutic approach for the subset of patients with a mutation in exons 19 or 21 of the EGFR. Another promising targeted approach involves the use of an anaplastic lymphoma kinase (ALK) inhibitor in patients with a translocation involving the echinoderm microtubule-associated protein-like 4 (EML4) and -ALK genes. Finally, a paradigm shift in favor of maintenance therapy for patients with advanced stage disease has gained strength from recent data. All of these advances have been made possible by developing a greater understanding of the biology, the discovery of novel anticancer agents, and improved supportive care measures. This article reviews the major strides made in the treatment of lung cancer in the recent past.

Targeted therapies for non-small cell lung cancer: an evolving landscape

Over the past decade, a multitude of targeted agents have been explored in the treatment of advanced non-small cell lung cancer (NSCLC). Thus far, two broad classes of agents have been implemented in clinical practice: (a) vascular endothelial growth factor (VEGF)-directed therapies and (b) antagonists of the epidermal growth factor receptor (EGFR). In the former category, the agent bevacizumab (a monoclonal antibody) has shown landmark improvements in survival when added to cytotoxic therapy. Small molecule tyrosine kinase inhibitors (TKI) targeting the VEGF receptor (i.e., sunitinib, sorafenib, and vandetanib) show activity in phase II clinical studies. With respect to EGFR-directed therapies, the TKIs gefitinib and erlotinib have shown significant benefit, and have uncovered valuable information about the biology of lung cancer. Outside of therapies directed specifically at VEGF- and EGFR-mediated signaling, trials evaluating insulin-like growth factor-1 receptor (IGF-IR)-targeting agents, cyclooxygenase-2 (COX-2) inhibitors, c-met inhibitors, irreversible pan-HER inhibitors, mammalian target of rapamycin (mTOR) inhibitors, and histone deacetylase (HDAC) inhibitors are ongoing. Inhibitors of ALK show great promise in patients with the relevant gene translocation. Herein, the clinical development of novel therapies for NSCLC is described, including some discussion of relevant biomarkers and determination of synergy with both cytotoxic therapy and other targeted agents.

Treatment outcomes of different prognostic groups of patients on cancer and leukemia group B trial 39801: induction chemotherapy followed by chemoradiotherapy compared with chemoradiotherapy alone for unresectable stage III non-small cell lung cancer

BACKGROUND

In Cancer and Leukemia Group B 39801, we evaluated whether induction chemotherapy before concurrent chemoradiotherapy would result in improved survival and demonstrated no significant benefit from the addition of induction chemotherapy. The primary objective of this analysis was to dichotomize patients into prognostic groups using factors predictive of survival and to investigate whether induction chemotherapy was beneficial in either prognostic group.

PATIENTS AND METHODS

A Cox proportional hazard model was used to assess the impact on survival of the following factors: (>or=70 versus <70 years), gender, race, stage (IIIB versus IIIA), hemoglobin (hgb) (<13 versus >or=13 g/dl), performance status (PS) (1 versus 0), weight loss (>or=5% versus <5%), treatment arm, and the interaction between weight loss and hgb.

RESULTS

Factors predictive of decreased survival were weight loss >or=5%, age >or=70 years, PS of 1, and hgb <13 g/dl (p < 0.05). Patients were classified as having >or=2 poor prognostic factors (n = 165) or <or=1 factor (n = 166). The hazard ratio (HR) for overall survival for the patients with >or=2 versus patients with <or=1 was 1.88 [95% confidence interval (CI), 1.49-2.37; p = <0.0001]; median survival times observed were 9 (95% CI, 8-11) and 18 (95% CI, 16-24) months, respectively. There was no significant difference in survival between treatment arms in patients with >or=2 factors (HR = 0.86, 95% CI, 0.63-1.17; p = 0.34) or <or=1 factor (HR = 0.97, 95% CI, 0.70-1.35; p = 0.87).

CONCLUSIONS

There is no evidence that induction chemotherapy is beneficial in either prognostic group.