P-394 Positron emission tomography with F18-fluorodeoxyglucose (FDG-PET) in malignant pleural mesothelioma (MPM): Prediction of response to chemotheraphy by quantitative assessment of standard uptake value (SUV)

Computer-assisted quantitative evaluation of therapeutic responses for lymphoma using serial PET/CT imaging

RATIONALE AND OBJECTIVES

Molecular imaging modalities such as positron emission tomography (PET)/computed tomography (CT) have emerged as an essential diagnostic tool for monitoring treatment response in lymphoma patients. However, quantitative assessment of treatment outcomes from serial scans is often difficult, laborious, and time consuming. Automatic quantization of longitudinal PET/CT scans provides more efficient and comprehensive quantitative evaluation of cancer therapeutic responses. This study develops and validates a Longitudinal Image Navigation and Analysis (LINA) system for this quantitative imaging application.

MATERIALS AND METHODS

LINA is designed to automatically construct longitudinal correspondence along serial images of individual patients for changes in tumor volume and metabolic activity via regions of interest (ROI) segmented from a given time point image and propagated into the space of all follow-up PET/CT images. We applied LINA retrospectively to nine lymphoma patients enrolled in an immunotherapy clinical trial conducted at the Center for Cell and Gene Therapy, Baylor College of Medicine. This methodology was compared to the readout by a diagnostic radiologist, who manually measured the ROI metabolic activity as defined by the maximal standardized uptake value (SUVmax).

RESULTS

Quantitative results showed that the measured SUVs obtained from automatic mapping are as accurate as semiautomatic segmentation and consistent with clinical examination findings. The average of relative squared differences of SUVmax between automatic and semiautomatic segmentation was found to be 0.02.

CONCLUSIONS

These data support a role for LINA in facilitating quantitative analysis of serial PET/CT images to efficiently assess cancer treatment responses in a comprehensive and intuitive software platform.

Phase II study of pemetrexed plus carboplatin in malignant pleural mesothelioma

PURPOSE

This multicenter, phase II clinical study was conducted to evaluate the activity of the combination of pemetrexed and carboplatin in patients with malignant pleural mesothelioma (MPM).

PATIENTS AND METHODS

Chemotherapy-naive patients with measurable disease and adequate organ function, who were not eligible for curative surgery, received pemetrexed 500 mg/m2 and carboplatin area under the plasma concentration-time curve of 5 mg/mL/min, administered intravenously every 21 days. All patients received folic acid and vitamin B12 supplementation. Pemetrexed was provided within the Expanded Access Program.

RESULTS

A total of 102 patients were enrolled. An objective response was achieved in 19 patients (two complete and 17 partial responses), for a response rate of 18.6% (95% CI, 11.6% to 27.5%). Forty-eight patients (47.0%; 95% CI, 37.1% to 57.2%) had stable disease after treatment. Overall, 67 patients (65.7%) achieved disease control (95% CI, 55.6% to 74.8%). Median time to progression was 6.5 months; median overall survival time was 12.7 months. Compliance to treatment was excellent, with a relative dose-intensity of 97% for pemetrexed and 98% for carboplatin. Toxicity was mild, with grade 3 or 4 neutropenia occurring in 9.7% of total cycles and grade 3 or 4 anemia occurring in 3.5% of total cycles. Nonhematologic toxicity was negligible.

CONCLUSION

Treatment with pemetrexed and carboplatin was active and well tolerated in patients with MPM. Disease control rate, time to disease progression, and overall survival were similar to the results achieved with the standard regimen of pemetrexed and cisplatin, suggesting that the carboplatin combination could be an alternative option for these patients.