Patient‐derived xenograft (PDX) models have shown to reflect original patient tumors better than any other preclinical model. We embarked in a study establishing a large panel of head and neck squamous cell carcinomas PDX for biomarker analysis and evaluation of established and novel compounds. Out of 115 transplanted specimens 52 models were established of which 29 were characterized for response to docetaxel, cetuximab, methotrexate, carboplatin, 5‐fluorouracil and everolimus. Further, tumors were subjected to sequencing analysis and gene expression profiling of selected mTOR pathway members. Most frequent response was observed for docetaxel and cetuximab. Responses to carboplatin, 5‐fluorouracil and methotrexate were moderate. Everolimus revealed activity in the majority of PDX. Mutational profiling and gene expression analysis did not reveal a predictive biomarker for everolimus even though by trend RPS6KB1 mRNA expression was associated with response. In conclusion we demonstrate a comprehensively characterized panel of head and neck cancer PDX models, which represent a valuable and renewable tissue resource for evaluation of novel compounds and associated biomarkers.

Purpose: Treatment options for recurrent/metastatic (R/M) head and neck squamous cell carcinoma (HNSCC) after failure of immune checkpoint inhibitor treatment and platinum-based chemotherapy are limited. Preliminary data suggested that monalizumab plus cetuximab had clinical activity in R/M HNSCC. Patients and Methods: INTERLINK-1 (NCT04590963) was a double-blind, phase III study. Participants with R/M HNSCC who had received immune checkpoint inhibitor therapy and progressed despite platinum-based chemotherapy were randomized 2:1 to monalizumab (750 mg, every 2 weeks) or placebo, plus cetuximab (400 mg/m2 loading dose, then 250 mg/m2, weekly). The primary endpoint was overall survival (OS) in participants with non-oropharyngeal cancer or human papillomavirus (HPV)-negative oropharyngeal cancer (HPV-unrelated analysis set). Secondary endpoints included progression-free survival and objective response rate. Results: At data cutoff, 216 participants were randomized in the HPV-unrelated analysis set: 145 to monalizumab plus cetuximab and 71 to placebo plus cetuximab. Median OS was 8.8 months for monalizumab plus cetuximab versus 8.6 months for placebo plus cetuximab (HR, 1.00; 95% confidence interval, 0.66–1.54); median progression-free survival was 3.6 versus 3.8 months, respectively (HR, 1.11; 95% confidence interval, 0.79–1.57); and the objective response rate was 15.2% versus 23.9%, respectively. INTERLINK-1 was terminated after a preplanned interim analysis showed that futility criteria were met (predetermined futility HR >0.874). Grade 3/4 treatment–related adverse events were reported in 18.3% and 17.2% of participants treated in the monalizumab and placebo arms, respectively. Conclusions: Monalizumab plus cetuximab did not improve OS compared with placebo plus cetuximab. The safety profile of the combination was consistent with safety observations for cetuximab monotherapy.

The poor prognosis of locally advanced and metastatic head and neck squamous cell carcinoma (HNSCC) is primarily mediated by the functional properties of cancer stem cells (CSCs) and resistance to chemoradiotherapy. We investigated whether the aldehyde dehydrogenase (ALDH) inhibitor disulfiram (DSF) can enhance the sensitivity of therapy. Cell viability was assessed by the 1-(4,5-dimethylthiazol-2-yl)-3,5-diphenylformazan (MTT) and apoptosis assays, and the cell cycle and reactive oxygen species (ROS) levels were evaluated by fluorescence-activated cell sorting (FACS). The radio-sensitizing effect was measured by a colony formation assay. The synergistic effects were calculated by combination index (CI) analyses. The DSF and DSF/Cu²⁺ inhibited the cell proliferation (inhibitory concentration 50 (IC₅₀) of DSF and DSF/Cu²⁺ were 13.96 μM and 0.24 μM). DSF and cisplatin displayed a synergistic effect (CI values were <1). DSF or DSF/Cu²⁺ abolished the cisplatin-induced G2/M arrest (from 52.9% to 40.7% and 41.1%), and combining irradiation (IR) with DSF or DSF/Cu²⁺ reduced the colony formation and attenuated the G2/M arrest (from 53.6% to 40.2% and 41.9%). The combination of cisplatin, DSF or DSF/Cu²⁺, and IR enhanced the radio-chemo sensitivity by inducing apoptosis (42.04% and 32.21%) and ROS activity (46.3% and 37.4%). DSF and DSF/Cu²⁺ enhanced the sensitivity of HNSCC to cisplatin and IR. Confirming the initial data from patient-derived tumor xenograft (PDX) supported a strong rationale to repurpose DSF as a radio-chemosensitizer and to assess its therapeutic potential in a clinical setting.