Novel Checkpoints Offer Hope After Standard Melanoma Immunotherapies Fail

“Determining the next step for a patient with melanoma who has failed or is not a candidate for existing targeted therapies or immunotherapies can be a challenge.

“However, there is hope, says Omid Hamid, MD, chief of Translational Research and Immunotherapy, and director of Melanoma Therapeutics at The Angeles Clinic.

“ ‘There are times when you throw your hands in the air and say, “I’ve run out of options,” ‘ he says. ‘But, all you need to do is look in another direction, open another cabinet, and realize that there are a ton of new options for our patients. These are nontraditional agents that maybe would not come to mind, but can be very effective in first-line, second-line, or any line.’

“Currently, several new checkpoint inhibitors and costimulatory molecules are being explored. These include those that target glucocorticoid-induced tumor necrosis factor receptor (GITR)—which is expressed on CD4- and CD8-positive T cells—in addition to T-regulatory cells, NK cells, and dendritic cells.”

Immune Checkpoint Inhibitors in Melanoma: New Directions

The drugs pembrolizumab (Keytruda) and nivolumab (Opdivo) were approved by the U.S. Food and Drug Administration (FDA) in 2014 and 2015, respectively. These two competing blockbuster drugs are already changing the outlook in metastatic melanoma, previously considered to be a fatal disease. Known as ‘immune checkpoint inhibitors,’ they work by releasing ‘brakes’ on a patient’s own immune system, freeing it to attack tumors. In the wake of their success, researchers are now taking immune checkpoint inhibition in new directions. Continue reading…

GITR-Dependent Regulation of 4-1BB Expression: Implications for T Cell Memory and Anti-4-1BB-Induced Pathology

The TNFR family member 4-1BB plays a key role in the survival of activated and memory CD8 T cells. However, the mechanisms that regulate 4-1BB re-expression on memory CD8 T cells after Ag clearance are unknown. In unimmunized mice, ∼10% of CD8 CD44hi memory T cells in the bone marrow (BM) and liver express 4-1BB, with minimal 4-1BB expression in spleen and lymph node. IL-2, IL-15, and IL-7 are collectively dispensable for 4-1BB expression on the memory CD8 T cells. Rather, T cell-intrinsic glucocorticoid-induced TNFR-related protein (GITR) contributes to 4-1BB expression on CD8 T cells upon their entry into the BM or liver…”