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Background Recurrent and/or metastatic squamous cell carcinoma of head and neck (R/M SCCHN) is a common cancer with high recurrence and mortality. Current treatments have low response rates (RRs). Methods Fifty-three patients with R/M SCCHN received continuous oral buparlisib. In parallel, patient-derived xenografts (PDXs) were established in mice to evaluate resistance mechanisms and efficacy of buparlisib/cetuximab combination. Baseline and on-treatment tumour genomes and transcriptomes were sequenced. Based on the integrated clinical and PDX data, 11 patients with progression under buparlisib monotherapy were treated with a combination of buparlisib and cetuximab. Results For buparlisib monotherapy, disease control rate (DCR) was 49%, RR was 3% and median progression-free survival (PFS) and overall survival (OS) were 63 and 143 days, respectively. For combination therapy, DCR was 91%, RR was 18% and median PFS and OS were 111 and 206 days, respectively. Four PDX models were originated from patients enrolled in the current clinical trial. While buparlisib alone did not inhibit tumour growth, combination therapy achieved tumour inhibition in three of seven PDXs. Genes associated with apoptosis and cell-cycle arrest were expressed at higher levels with combination treatment than with buparlisib or cetuximab alone. Conclusions The buparlisib/cetuximab combination has significant promise as a treatment strategy for R/M SCCHN. Clinical Trial Registration NCT01527877.

Primers used in qRT-PCR, RT-PCR, and ChIP-qPCR. F, forward primer; R, reverse primer. (PDF 90 kb)

EMSA on binding of MBP and MBP-CCA1 proteins to conserved sequences in FT locus. Recombinant MBP and MBP-CCA1 fusion proteins were prepared as described in Additional file 5. Radio-labelled CCA1-binding sequence (CBS) and evening element (EE) DNA fragments, which were described in Fig. 4a, were used. A. EMSA on MBP binding to DNA fragments. (+) and (â ) indicate assays with or without MBP protein. Note that MBP alone does not bind to the CBS and EE sequences. B. EMSA on MBP-CCA1 binding to DNA fragments. The core sequences of CBS and EE were mutated, resulting in mCBS and mEE, respectively. Excess amounts (50X, 100X) of unlabeled DNA fragments were added as competitors. (PDF 182 kb)

Recombinant proteins used for electrophoretic mobility shift assay (EMSA). Recombinant maltose-binding protein (MBP) and MBP-CCA1 fusion protein were prepared in E. coli cells and affinity-purified. Protein quality was verified by running on 10Â % SDS-PAGE and Coomassie brilliant blue staining. The arrow and arrowhead indicate full-size MBP and MBP-CCA1 proteins, respectively. SM, size marker. kDa, kilodalton. (PDF 263 kb)

Expression of flowering genes in lhy-7 mutant under short days of 20-h total duration. Plants were grown for 10 days under short-day cycles of either 24-h (8-h light and 16-h dark) or 20-h (6.7-h light and 13.3-h dark) total duration. Whole plant materials were harvested throughout the % light-dark (L/D) cycles. Transcript levels were examined by qRT-PCR in Col-0 plants (A) and lhy-7 mutant (B). Biological triplicates were averaged. Bars indicate standard error of the mean. h, hour. (PDF 133 kb)

ChIP assays on LHY binding to GI promoter. Chromatins were prepared from 7-day-old whole plants grown on MS-agar plates and immunoprecipitated using an anti-MYC antibody. Fragmented genomic DNA was eluted from the protein-DNA complexes and subjected to quantitative PCR. Biological triplicates were averaged and statistically treated using Student t-test (*Pâ

Expression of flowering genes in lhy-7 mutant under SDs of 20-h total duration. Plants were grown for 10 days under short-day cycles of 20-h total duration (6.7-h light and 13.3-h dark). Whole plant materials were harvested for total RNA extraction. Transcript levels were examined by qRT-PCR. Biological triplicates were averaged and statistically treated using Student t-test (*P

Functionality of 35S:MYC-CCA1 and 35S:LHY-MYC transgenic plants. A and B. Elongated hypocotyls. Plants were grown on MS-agar plates for 5 days under either LDs (A) or SDs (B). Measurements of 20 seedlings were averaged and statistically treated (t-test, *P

Levels of LHY and CCA1 transcripts in 35S:LHY-MYC and 35S:MYC-CCA1 transgenic plants, respectively. Ten-day-old whole plants grown on MS-agar plates under LDs were harvested for total RNA extraction at the indicated ZT points. Transcript levels were examined by qRT-PCR. Biological triplicates were averaged and statistically treated (t-test, *Pâ

Expression of flowering time genes in lhy-7 mutant. Plants were grown under either LDs or short days (SDs, 8-h light and 16-h dark) for 10 days on MS-agar plates. Whole plants were harvested at ZT 8 for total RNA extraction. Transcript levels were examined by qRT-PCR. Biological triplicates were averaged and statistically treated using Student t-test (*P