Targeted ImmunoPET Scans Identify Active Multiple Myeloma Missed by Traditional Methods

A targeted immunoPET scan demonstrated effectiveness in detecting active multiple myeloma that standard PET/CT scans and blood tests overlooked. This research from Sylvester Comprehensive Cancer Center, part of the University of Miami Miller School of Medicine, underscores the need for more precise disease mapping, which can enhance treatment decisions and confirm the absence of cancer post-therapy.

Multiple myeloma is characterized by its growth in the bone marrow and potential spread to various body locations. Traditional imaging techniques and newer blood tests are often inadequate, potentially impacting diagnosis and treatment strategies.

C. Ola Landgren, M.D., Ph.D., the study's senior author, emphasized the importance of novel imaging techniques, stating, "If we are going to cure multiple myeloma, we need two things. One, we need really effective medicines. Second, we need to be able to make sure there is no disease left behind after these treatments."

In this phase 2 clinical trial, researchers utilized immunoPET—an approach using labeled antibodies that target myeloma cells directly. Standard PET/CT scans typically rely on glucose uptake to identify tumors, but this method can miss myeloma in up to 40% of cases due to similar glucose consumption patterns between myeloma and normal cells.

"Myeloma cells frequently consume the same amount of glucose as the surrounding normal cells," noted Landgren. The study involved 60 patients who underwent both a conventional glucose-based PET/CT scan and the immunoPET scan. Results revealed that over 10% of patients exhibited disease signals exclusive to the immunoPET scans, confirmed via follow-up biopsies.

For example, one patient with back pain but normal blood tests had myeloma lesions identified by the immunoPET scan, leading to changes in treatment and subsequent resolution of symptoms. Additionally, in one instance, a patient presented with negative standard scans, yet the immunoPET indicated nearly 100 myeloma sites throughout the body.

The study's findings indicate that immunoPET uncovered active disease in 17 patients (28%) that standard scans missed, while standard scans identified cases in 13 patients (22%) that immunoPET did not. Overall, both imaging methods detected similar amounts of disease in the remaining patients.

Landgren emphasized that the intent is not to replace existing diagnostic tools but to complement them. He stated, "We show that you can successfully find much more disease. It's a more sensitive and more precise technology, and we have very strong proof of principle that it works and that it's meaningful."

Despite its efficacy, the current immunoPET version has limitations, including a week-long waiting period for the antibody to circulate and attach to cancer cells. Future developments aim to create smaller antibody fragments that would allow for quicker testing, potentially facilitating same-day assessments for routine use.

Source: University of Miami Miller School of Medicine