Phosphoinositide 3-kinase (PI3K) pathway alterations are associated with histologic subtypes and are predictive of sensitivity to PI3K inhibitors in lung cancer preclinical models

PURPOSE

Class 1 phosphatidylinositol 3-kinase (PI3K) plays a major role in cell proliferation and survival in a wide variety of human cancers. Here, we investigated biomarker strategies for PI3K pathway inhibitors in non-small-cell lung cancer (NSCLC).

EXPERIMENTAL DESIGN

Molecular profiling for candidate PI3K predictive biomarkers was conducted on a collection of NSCLC tumor samples. Assays included comparative genomic hybridization, reverse-transcription polymerase chain reaction gene expression, mutation detection for PIK3CA and other oncogenes, PTEN immunohistochemistry, and FISH for PIK3CA copy number. In addition, a panel of NSCLC cell lines characterized for alterations in the PI3K pathway was screened with PI3K and dual PI3K/mTOR inhibitors to assess the preclinical predictive value of candidate biomarkers.

RESULTS

PIK3CA amplification was detected in 37% of squamous tumors and 5% of adenocarcinomas, whereas PIK3CA mutations were found in 9% of squamous and 0% of adenocarcinomas. Total loss of PTEN immunostaining was found in 21% of squamous tumors and 4% of adenocarcinomas. Cell lines harboring pathway alterations (receptor tyrosine kinase activation, PI3K mutation or amplification, and PTEN loss) were exquisitely sensitive to the PI3K inhibitor GDC-0941. A dual PI3K/mTOR inhibitor had broader activity across the cell line panel and in tumor xenografts. The combination of GDC-0941 with paclitaxel, erlotinib, or a mitogen-activated protein-extracellular signal-regulated kinase inhibitor had greater effects on cell viability than PI3K inhibition alone.

CONCLUSIONS

Candidate biomarkers for PI3K inhibitors have predictive value in preclinical models and show histology-specific alterations in primary tumors, suggesting that distinct biomarker strategies may be required in squamous compared with nonsquamous NSCLC patient populations.

Cardiovascular toxicities: clues to optimal administration of vascular endothelial growth factor signaling pathway inhibitors

Several angiogenesis inhibitors have been approved for commercial use and many additional agents are under development for the treatment of various malignancies. Cardiovascular toxicities have been increasingly recognized as effects of this entire class of new anticancer therapeutics. There is a limited but growing understanding of the mechanism of action of these drugs in the human cancer patient and the factors affecting the therapeutic index. In addition to reviewing current concepts for the cardiovascular toxicities of angiogenesis inhibitors, we discuss how better understanding the pharmacologic basis for these effects could optimize their use for individual patients.

[Bevacizumab and non-small cell lung cancer: a new step?]

Inhibition of specific processes essential for tumour vascular development is one of the key strategies for the treatment of non- small cell lung cancer (NSCLC). Many agents target the Vascular Endothelial Growth Factor (VEGF) pathway, either by preventing VEGF receptor binding or inhibiting VEGF receptor signalling in endothelial cells. Bevacizumab is a monoclonal antibody specific for VEGF-A. Combination of bevacizumab with standard first-line chemotherapy in NSCLC leads to an improvement in response rates and progression-free survival compared to chemotherapy alone and a significant survival advantage with carboplatin- paclitaxel chemotherapy. Toxicity issues are of concern with the possible occurrence of hypertension and an increased risk of arterial thrombo-embolism. The occurrence of fatal pulmonary haemorrhage after necrosis of the primary tumour is a specific toxicity in NSCLC which requires appropriate selection of patients before treatment; excluding squamous cell carcinoma, haemorrhagic tumours and tumour invasion of major blood vessels. The use of bevacizumab combined with chemotherapy represent a first step in the development of antiangiogenic treatments in NSCLC, with the future possibility of using it in earlier stages of disease.

Tumor cavitation: impact on objective response evaluation in trials of angiogenesis inhibitors in non-small-cell lung cancer

PURPOSE

We have observed cavitation of lesions in clinical trials of an angiogenesis inhibitor combined with chemotherapy for non-small-cell lung cancer (NSCLC). We hypothesized that cavitation might alter response assessment in such clinical trials.

PATIENTS AND METHODS

We performed a retrospective radiologic review of patients with NSCLC enrolled onto three National Cancer Institute of Canada Clinical Trials Group (NCIC CTG) trials of platinum-based chemotherapy with or without a small-molecule angiogenesis inhibitor (vascular endothelial growth factor receptor inhibitor [VEGFRI]). Response was assessed both by Response Evaluation Criteria in Solid Tumors (RECIST) guidelines and a novel alternate method in which the longest diameter of any cavity was subtracted from the overall longest diameter of that lesion to measure target lesions. Rates of cavitation were documented.

RESULTS

Marked cavitation of pulmonary lesions was seen in 24% of 33 patients treated with VEGFRI combined with platinum-based chemotherapy but in none of 18 patients treated with platinum-based chemotherapy alone. Use of the alternate method for response assessment resulted in an alteration of response assessment, time to best response, duration of response, and time of disease progression in a minority of patients compared with RECIST.

CONCLUSION

Cavitation of target and nontarget lesions is common in NSCLC patients treated with VEGFRIs and platinum-based chemotherapy. Impact on response and time to event outcomes occurred but seems to be less common. Response assessment might be improved by incorporating cavitation into volume assessment for target lesions, potentially altering outcomes of key efficacy parameters in clinical trials. This should be prospectively assessed in clinical trials of angiogenesis inhibitors.

Tumor cavitation during therapy with antiangiogenesis agents in patients with lung cancer

PURPOSE

Treatment of lung cancer patients with antiangiogenesis agents is a new promising paradigm. Tumor cavitation is frequently noted in these patients, but the clinical significance of this finding has not been fully determined. Our purposes were to evaluate the frequency, imaging characteristics, and clinical outcome of patients receiving antiangiogenesis agents who develop tumor cavitation, and correlate these findings with therapy related adverse events, especially hemoptysis.

METHODS

Retrospective analysis of lung cancer patients treated with antiangiogenesis agents in MD Anderson Cancer Center between June 1998 and June 2005. Clinical data were retrieved from medical records, and chest imaging findings were documented.

RESULTS

One hundred and twenty-four patients were treated in 10 different trials. All patients had advanced lung cancer and failed previous chemotherapy. Seventeen patients developed tumor cavitation during the trial (14%; median time to event, 1.8 months; range, 0.7-6.2 months), 16 patients (13%) had preexisting cavitary tumors, and 91 (73%) did not develop cavitation. Cavity formation was more common with squamous cell histology (p = 0.04) but was not associated with hemoptysis (p = 0.12), tumor location (central versus peripheral), imaging characteristics, progression-free survival (p = 0.56), or overall survival (p = 0.33). Hemoptysis was noted in five patients (median time to event, 1.3 months; range, 0.8-2.9 months). One of five patients with hemoptysis was fatal in a cavitary squamous cell tumor. Additional adverse events were hypertension, rash, and proteinuria, none associated with cavitation.

CONCLUSION

Development of tumor cavitation is not rare in lung cancer patients treated with antiangiogenesis agents, but the clinical implications are minimal in most cases.

Bevacizumab in non small cell lung cancer

Angiogenesis, the growth of new vessels from preexisting vessels, is a fundamental step in tumor growth and progression. Vascular endothelial growth factor (VEGF) is a key angiogenic factor implicated in tumor blood vessel formation and permeability. Overexpression of VEGF has been observed in a variety of cancers and has been associated with a worse relapse-free and overall survival. The antiangiogenic agent bevacizumab, a monoclonal antibody directed against VEGF, has shown clinical benefit in multiple cancers, including non-small cell lung cancer (NSCLC). Based on the favorable results of a prior randomized, phase II trial, the Eastern Cooperative Oncology Group conducted a trial (E4599) to evaluate the efficacy of bevacizumab in combination with paclitaxel and carboplatin in patients with recurrent or advanced stage IIIB or IV nonsquamous cell NSCLC. Exclusion criteria included squamous cell histology, brain metastases, significant hemoptysis, or inadequate organ function or performance status >1. The primary study end point was overall survival. The median duration of survival in the chemotherapy plus bevacizumab group was 12.3 months compared with 10.3 months in the chemotherapy alone group (P = 0.003). Significant bleeding was more frequent in the chemotherapy plus bevacizumab group, 4.4% compared with 0.9% (P = 0.001). There were 15 treatment-related deaths in the chemotherapy plus bevacizumab group, including 5 due to pulmonary hemorrhage. Future and current directions include evaluation of bevacizumab in earlier stages of NSCLC, in SCLC, and in combination with other targeted agents, such as erlotinib.

Bevacizumab in the treatment of non-small-cell lung cancer

Lung cancer is the leading cause of cancer death in the United States. The majority of patients present with advanced disease, and treatment with standard cytotoxic chemotherapy improves survival and quality of life in patients with a preserved functional status. However, the prognosis is poor with the majority of patients dying in less than a year. Treatment with standard cytotoxic chemotherapy has reached a therapeutic plateau, and new therapeutic approaches have investigated therapies that target the specific molecular pathways involved in carcinogenesis and angiogenesis. The most promising strategy for inhibiting angiogenesis involves agents that either target the proangiogenesis growth factor, vascular endothelial growth factor A (VEGF) by preventing binding to the receptor or inhibiting the downstream signaling of the vascular endothelial growth factor receptor. The only therapeutic agent approved for the treatment of lung cancer is bevacizumab, a monoclonal antibody that binds to VEGF. A recent phase III trial revealed a statistically significant improvement in response rate, progression free and overall survival with combination of bevacizumab with chemotherapy over chemotherapy alone. Attempts to identify surrogate markers of antiangiogenesis activity are currently ongoing, and may assist in the selection of patients for antiangiogenesis therapy and the development of this class of agents.

Toxicities of Antiangiogenic Therapy in Non–Small-Cell Lung Cancer

The addition of antiangiogenic agents has improved overall survival in a wide variety of tumor types, including non-small-cell lung cancer (NSCLC). Antibodies to the vascular endothelial growth factor (VEGF) were the first targeted agent to yield a significant improvement in overall survival when combined with first-line chemotherapy for metastatic NSCLC. Anti-VEGF antibodies and tyrosine kinase inhibitors blocking VEGF receptor (VEGFR) activity are also being investigated in pretreated NSCLC. Initial experience with anti-VEGF antibodies suggested a mild adverse event profile. However, it has become clear with additional experience that antiangiogenic agents are associated with a distinct array of toxicities, such as hemorrhage, hypertension, thromboembolic events, and proteinuria. Furthermore, an increase in chemotherapy-associated toxicities such as neutropenia has been observed with the addition of anti-VEGF antibodies. Multitargeted small-molecule inhibitors that block activity of the VEGFR tyrosine kinase are associated with fatigue and other toxicities in addition to the aforementioned class-effect toxicities, possibly because of their inhibition of multiple signaling pathways. Currently, only patients without predominant squamous cell histology are eligible to receive bevacizumab. Trials are ongoing to address the feasibility of bevacizumab in patients who were excluded from the phase III pivotal trial. Additionally, further investigation is necessary to determine risk factors for hemorrhage with antiangiogenic agents.