Monitoring Targeted Therapy in Ovarian Cancer with PET Probe

A molecular imaging technique shows potential for monitoring early response to treatment for cisplatin-resistant ovarian tumors.

Research reported in the October 2010 issue of the Journal of Nuclear Medicine (JNM) revealed that a positron emission tomography (PET) imaging with a certain probe might prove useful in early assessment of treatment response for cisplatin-resistant ovarian cancer.

"One of the most promising aspects of molecular imaging is its potential capacity to measure therapy effects long before changes in the tumor size and shape are detected,” said Dr. Marijke De Saint-Hubert, medical scientist in the department of nuclear medicine at the University Hospital Gasthuisberg (Leuven, Belgium), and one of the authors on an invited perspective article in JNM that commented on the study. It is important to identify response to therapy as early as possible so that ineffective therapies can be discontinued. Patients who are not responding to a given therapy may be suffering from unnecessary side effects and may also be offered potentially more effective treatments.

The chemotherapy drug cisplatin is frequently effective against ovarian cancer when first given; however, tumors can become resistant to the drug and start growing again, so the need for second-line therapies is pressing. One potential way to overcome cisplatin resistance is to target the mammalian target of rapamycin (mTOR) pathway. The aim of the study was to evaluate the ability of ¹⁸F-FLT (3'-deoxy-3'-[¹⁸F]fluorothymidine), a PET probe for cell proliferation, to predict early response to everolimus (an mTOR inhibitor) in a mouse model of subcutaneously transplanted human cisplatin-resistant ovarian cancer.

The study showed that ¹⁸F-FLT PET was able to predict early response to mTOR inhibition in a cisplatin-resistant ovarian cancer in mice. The researchers suggest that this technique should be considered for therapeutic evaluation in humans. They also pointed out the technique's potential to monitor noninvasively and longitudinally the efficacy of combination therapy.

"PET imaging could be used to evaluate the treatment's efficacy very early after treatment initiation--at a time when conventional criteria based on tumor size measurements are useless,” said Nicolas Aide, M.D., Center for Molecular Imaging at the Peter MacCallum Cancer Center (East Melbourne, Australia), one of the authors of the study.

Related Links:
University Hospital Gasthuisberg
Peter MacCallum Cancer Center