FDG–PET Evaluates Immunotherapy for Non–Small Cell Lung Cancer


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Researchers at the 2016 Annual Meeting of the Society of Nuclear Medicine and Molecular Imaging (SNMMI) presented study findings on a means of evaluating an immunotherapy for non–small cell lung cancer (NSCLC).1 Due to NSCLC’s relative insensitivity to chemotherapy, the use of immunotherapies, including a class of monoclonal antibodies that serve as immune checkpoint blockade inhibitors, has been explored.

Potential Biomarker in Lung Cancer

  • Researchers used quantitative FDG–PET, both at baseline before study treatment and again after 6 weeks of treatment with atezolizumab.
  • Higher baseline tumor volumes of FDG were predictive of reduced patient survival, suggesting that greater active tumor volume at the start of therapy may be a sign of poorer survival. A further increase in tumor volume at 6 weeks may be a sign of decreased patient survival.

In this study, researchers investigated the immunotherapeutic atezolizumab (Tecentriq), which inhibits activity between the programmed cell death protein 1 (PD-1) receptor expressed on certain immune cells and the programmed cell death ligand 1 (PD-L1), a transmembrane protein found on the surface of tumor cells.

Researchers have tracked the ability of atezolizumab to bolster immunity against NSCLC with the use of fluorine-18 fluorodeoxyglucose (FDG) positron-emission tomography (PET). FDG–PET allows clinicians to see areas of increased metabolic activity in cells and change in metabolic activity following drug treatment.

Study Details and Findings

This multicenter study included a total of 138 patients with NSCLC from 28 clinical institutions in 5 different countries. All patients received 1,200 mg of atezolizumab administered intravenously in 3-week intervals. Researchers used quantitative FDG–PET, both at baseline before study treatment and again after 6 weeks of treatment with atezolizumab.

These findings help define the potential role of FDG–PET as a prognostic and predictive biomarker in the treatment of lung cancer with such immunotherapeutics [atezolizumab].
— Jill Fredrickson, PhD

The study revealed that higher baseline tumor volumes of FDG were predictive of reduced patient survival, suggesting that greater active tumor volume at the start of therapy may be a sign of poorer survival. In addition, a further increase in tumor volume at 6 weeks was a sign of decreased patient survival. Although atezolizumab and other immune checkpoint inhibitors work differently from conventional chemotherapy, FDG–PET may be used with either treatment to assess how well patients with NSCLC may respond to therapy.

“This study is the first to prospectively evaluate FDG–PET imaging in a phase II trial of lung cancer patients receiving the novel immune checkpoint inhibitor atezolizumab,” said Jill Fredrickson, PhD, a clinical imaging scientist in the Department of Early Clinical Development at Genentech. “These findings help define the potential role of FDG–PET as a prognostic and predictive biomarker in the treatment of lung cancer with such immunotherapeutics.” ■

Disclosure: Dr. Fredrickson is employed by Genentech as a Clinical Imaging Scientist in the Department of Early Clinical Development. Genentech manufactures and markets atezolizumab as Tecentriq.

Reference

1. Fredrickson J, Callahan J, Funke R, et al: Utility of FDG-PET in immunotherapy: Results from a phase II study of NSCLC patients undergoing therapy with the PD-L1 inhibitor atezolizumab (MPDL3280A). 2016 Society of Nuclear Medicine and Molecular Imaging Annual Meeting. Abstract 134.



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