Researchers at Sylvester Comprehensive Cancer Center have evaluated a targeted imaging approach designed to reveal multiple myeloma that standard glucose-based PET/CT scans may miss. The multicenter phase 2 trial, published in Radiology, compared CD38-targeted immunoPET with standard FDG PET/CT in 60 patients, providing a clearer look at active disease that often remains hidden in bone marrow.
Trial Tests ImmunoPET Against Standard Scans
Myeloma cells frequently consume the same amount of glucose as the surrounding normal cells,
said Dr. C. Ola Landgren, chief of the Myeloma Division and director of Sylvester Myeloma Institute. It’s very well known among radiologists and myeloma experts that some patients who have myeloma in their bones may not light up on PET scans. The methods are simply not designed to reliably capture multiple myeloma.
Standard PET/CT scans rely on the principle that tumor cells consume larger amounts of glucose than surrounding normal cells. In up to 40% of cases, standard scans miss residual disease because abnormal glucose uptake is absent. Investigators developed a tracer compound by labeling antibodies designed to recognize a myeloma-specific surface protein called CD38. After testing the approach in laboratory models alongside collaborators at Hoag Cancer Center, the team advanced the work into human studies and the multicenter phase 2 clinical trial involving 60 patients with multiple myeloma.
Trial Reveals Hidden Lesions With ImmunoPET
Patients in the trial underwent both standard glucose-based PET/CT scans and the antibody-based immunoPET scan. ImmunoPET detected active disease missed by standard scans in 17 patients, or 28%. Standard FDG PET/CT detected disease missed by immunoPET in 13 patients, or 22%, indicating that both methods offer complementary information rather than a complete replacement for existing tools.
Their standard tests showed no evidence of disease, but we found nearly 100 sites of myeloma throughout the body,
said Dr. Landgren. These are exactly the kinds of patients who benefit from better scans.
More than 10% of participants showed disease signals exclusively on the immunoPET scans, which subsequent biopsies confirmed as active myeloma. In one instance, a patient experiencing persistent back pain with normal blood markers and standard imaging underwent the antibody-based scan, which uncovered myeloma lesions in the spine. Following a treatment switch, the patient’s pain resolved. In another case, a patient with negative conventional scans and blood tests was found to have widespread disease.
Researchers Aim for Same-Day Testing
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,
said Dr. Landgren. We are developing new and better technology designed to see where the disease is and make sure we are not missing it.
Dr. Landgren described the work as: We started with an idea, tested it in the laboratory, brought it into patients and then showed it could answer clinically important questions.
It takes a week for the antibody to circulate through the body and attach to cancer cells, complicating the administration schedule. To address this, Dr. Landgren and his colleagues are developing next-generation iterations utilizing smaller antibody fragments capable of reaching tumors more rapidly.