We have already learned that responses to immunotherapy may be delayed; that there can be pseudoprogression....where tumors look as if they have grown due to the influx of fighting T cells and inflammation and mayhem that causes. But now, there's this:
Residual FDG-PET metabolic activity in metastatic
melanoma patients with prolonged response to anti-PD-1 therapy. Kong, Menzies, Saunders, et al.
Pigment Cell Melanoma Res. 2016 Jun 22.
FDG-PET scans were performed
on twenty seven patients with unresectable stage IIIC or IV melanoma after
prolonged treatment with anti-PD-1 antibodies to examine the hypothesis that
patients with prolonged response to treatment may have metabolically inactive
lesions by FDG-PET. Scans were performed at a median of 15.2 months (range
12-29 months) after starting treatment. Overall 15/27 (56%) patients had a
positive FDG-PET scan. Eight patients with positive scans underwent biopsy; 5/8
(62%) were melanoma and 3/8 (38%) were immune cell infiltrates. Of the 12
patients with negative FDG-PET scans, 6 had residual CT visible lesions, 5 have
ceased treatment and none have recurred with follow up of 6 to 10 months.
Patients with residual metastases after a prolonged period without progression
on anti-PD-1 therapy may have metabolically inactive lesions. Isolated
metabolically active lesions in clinically well patients may reveal immune cell
infiltrates rather than melanoma.
FYI! - c
FYI! - c
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