FAP is a prognostic marker, but not a viable therapeutic target for clinical translation in HNSCC.

PURPOSE: PD-1 targeted immunotherapy has imparted a survival benefit to advanced head and neck squamous cell carcinoma (HNSCC), but less than 20% patients produce a durable response to this therapy. Here we aimed to investigate the potential biomarkers for predicting the clinical outcome and resistance to PD-1 targeted immunotherapy in HNSCC patients, and to examine the involvement of FAP+ cancer-associated fibroblasts (CAFs). METHODS: Bioinformatics methods were applied to analyze multiple datasets and explore the role of PD-1 and FAP in HNSCC. Immunohistochemistry was used to detect the expression of FAP protein. Fap gene knockout mice (Fap-/-) and L929 cells with different levels of Fap overexpression (L929-Fap-Low/High) were established to demonstrate the role of FAP+ CAFs in tumor development and immune checkpoint blockade (ICB) resistance. RESULTS: The expression level of PD-1 gene was positively correlated with better overall survival and therapeutic response to PD-1 blockade in HNSCC, but not all tumors with high expression of both PD-1 and PD-L1 were responsive. Moreover, FAP gene was overexpressed in pan-cancer tissues, and could serve as a prognostic biomarker for several cancers, including HNSCC. However, FAP protein was undetectable in mouse MTCQ1 tumors and barely expressed in human HNSCC tumors. Furthermore, FAP+ CAFs did not promote tumor growth or enhance the resistance to PD-1 inhibitor treatment. CONCLUSION: Although FAP+ CAFs have attracted increasing attention for their role in cancer, the feasibility and efficacy of FAP-targeting therapies for HNSCC remain doubtful.

Saucy-Marbet Rearrangements of Alkynyl Halides in the Synthesis of Highly Enantiomerically Enriched Allenyl Halides.

A stereospecific Saucy-Marbet rearrangement of alkynyl halides is described here. These rearrangements provide an entry to highly enantiomerically enriched allenyl bromides and chlorides through excellent chirality transfer and the reservation of optical integrity of alkynyl halides.

Copper(II)-catalyzed amidations of alkynyl bromides as a general synthesis of ynamides and Z-enamides. An intramolecular amidation for the synthesis of macrocyclic ynamides.

A general and efficient method for the coupling of a wide range of amides with alkynyl bromides is described here. This novel amidation reaction involves a catalytic protocol using copper(II) sulfate-pentahydrate and 1,10-phenanthroline to direct the sp-C-N bond formation, leading to a structurally diverse array of ynamides including macrocyclic ynamides via an intramolecular amidation. Given the surging interest in ynamide chemistry, this atom economical synthesis of ynamides should invoke further attention from the synthetic organic community.

Copper-catalyzed stereospecific N-allenylations of amides. Syntheses of optically enriched chiral allenamides.

[reaction: see text] Syntheses of chiral allenamides via a stereospecific amidation of optically enriched allenyl iodides using catalytic copper(I) salt and N,N'-dimethylethylene-diamine are described here.

Highly regioselective radical cyclizations of allenamides.

The first radical cyclizations of allenamides are described. These reactions are highly regioselective for the central carbon of the allenic moiety, leading to an efficient preparation of nitrogen heterocycles such as isoquinolines, and carbocycles such as indane and naphthalene derivatives. The exo-cyclization mode could also be achieved in some cases, leading to the synthesis of isoindoles. The feasibility of a tandem radical cyclization using allenamide is also established. [reaction: see text]

Highly stereoselective synthesis of novel alpha-haloenamides via a mild and efficient hydrohalogenation of ynamides.

A highly stereoselective preparation of novel chiral (E)-alpha-haloenamides under mild conditions utilizing magnesium halide salts is described. This unexpected mild and efficient hydrohalogenation reaction highlights another synthetic utility of ynamides. [reaction: see text]

A copper-catalyzed C-N bond formation involving sp-hybridized carbons. A direct entry to chiral ynamides via N-alkynylation of amides.

A copper-catalyzed new C-N bond formation involving a sp-hybridized carbon is described here leading to a facile entry for syntheses of chiral ynamides. This direct N-alkynylation of amides should have a significant impact on the future development of synthetic methodologies employing ynamides.