41 research outputs found
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Resistance to checkpoint blockade therapy through inactivation of antigen presentation
Treatment with immune checkpoint blockade (CPB) therapies often leads to prolonged responses in patients with metastatic melanoma, but the common mechanisms of primary and acquired resistance to these agents remain incompletely characterized and have yet to be validated in large cohorts. By analyzing longitudinal tumor biopsies from 17 metastatic melanoma patients treated with CPB therapies, we observed point mutations, deletions or loss of heterozygosity (LOH) in beta-2-microglobulin (B2M), an essential component of MHC class I antigen presentation, in 29.4% of patients with progressing disease. In two independent cohorts of melanoma patients treated with anti-CTLA4 and anti-PD1, respectively, we find that B2M LOH is enriched threefold in non-responders (~30%) compared to responders (~10%) and associated with poorer overall survival. Loss of both copies of B2M is found only in non-responders. B2M loss is likely a common mechanism of resistance to therapies targeting CTLA4 or PD1
Regio- and stereospecific synthesis of C-3 functionalized proline derivatives by palladium catalyzed ddirected C(sp3)âH Arylation
Functionalization of C(sp3)âH bonds at the unactivated 3-position of proline derivatives has been achieved using aryl iodides and palladium catalysis. This directly affords cis-2,3-disubstituted pyrrolidines as single stereoisomers. 3- Arylation occurs in high yield under solvent-free conditions with aminoquinoline and methoxyaminoquinoline directing groups. The latter was readily removed to give primary amide derivatives with physicochemical properties appropriate for use as fragments in drug discovery