99mTechnetium-SESTAMIBI uptake in malignant lymphomas. Correlation with chemotherapy response.

Background: The rationale of the present study is based on the property of technetium-SESTAMIBI to enter malignant and other highly metabolic cells, and then to be pumped out of them by the multidrug-resistant (MDR) system, strongly depending on the expression of the MDR-1 gene encoded P-glycoprotein (Pgp-170).

Methods And Results: Forty-one patients with malignant lymphoma were studied before chemotherapy. Images were taken 30 min (early) and 180 min (late) after intravenous injection of (99m)Tc-MIBI, and then visually interpreted. They were correlated with clinical response defined as chemosensitive (ChS) when a >6 month remission was attained, and chemoresistant (ChR) to any other response. Of 41 patients, 27 had an early positive uptake, 18 (67%) were ChS, and 9 (33%) ChR. Of these 27 patients, 19 also had late positive scans; 15 (79%) were ChS, and only 4 were ChR (p = 0.037). Conversely, 10 of 14 remaining patients with negative early scans were ChR. Eight patients had an early positive study; however, the late retention of (99m)Tc-MIBI was negative and the relationship to chemotherapy response was not conclusive. A breakdown of data was made according to histology. Patients with low grade lymphoma had the strongest correlation between (99m)Tc-MIBI uptake and chemosensitivity. Patients with high grade lymphoma had only a trend, and patients with Hodgkin's disease had an indefinable correlation.

Conclusions: This study takes advantage of the relationship between the ability to uptake and retain (99m)Tc-MIBI, a Pgp-170 substrate, by lymphomatous tumors. This attribute, combined with other clinical data, could help to select tailored treatments for patients that are likely to be chemoresistant before treatment.