Durvalumab in combination with chemoradiotherapy in patients with head and neck squamous cell carcinoma: Results from the Phase 1 CLOVER study.

BACKGROUND: The Phase 1 CLOVER study (NCT03509012) assessed durvalumab in combination with concurrent chemoradiotherapy (cCRT) in patients with advanced solid tumors; we report results from the head and neck squamous cell carcinoma (HNSCC) cohort. METHODS: Patients with histologically/cytologically confirmed locally advanced HNSCC, eligible for definitive cCRT and not considered for primary surgery, received durvalumab plus cisplatin and concurrent external beam radiation. Objectives were to assess safety/tolerability and preliminary efficacy. RESULTS: Eight patients were enrolled. The most frequent any-cause adverse events (AEs) were nausea and radiation skin injury (each n = 5); most frequent grade 3/4 AEs were lymphopenia and stomatitis (each n = 3). No patients had dose-limiting toxicities. Objective response rate was 71.4% (5/7 patients; four complete responses, one partial response); disease control rate was 85.7% at 18 weeks and 83.3% at 48 weeks. CONCLUSIONS: Durvalumab plus cCRT was tolerable and active in patients with unresected, locally advanced HNSCC.

Durvalumab in combination with chemoradiotherapy for patients with unresectable stage III non-small-cell lung cancer: Results from the phase 1 CLOVER study.

INTRODUCTION: For patients with unresectable, stage III non-small-cell lung cancer (NSCLC), current standard of care is concurrent chemoradiotherapy (cCRT) followed by consolidation durvalumab. However, earlier initiation of durvalumab simultaneously with cCRT may increase antitumor activity relative to initiation after cCRT. The phase 1 CLOVER study (NCT03509012) evaluated durvalumab combined with cCRT in patients with advanced solid tumors; we report findings from the NSCLC cohort. METHODS: CLOVER comprised a dose-limiting toxicity (DLT) assessment part, followed by an expansion part. In the NSCLC cohort, patients with previously untreated, unresectable, stage III NSCLC were enrolled in three treatment arms: durvalumab every 4 weeks (Q4W) + cisplatin + etoposide + radiotherapy (Arm 1); durvalumab Q4W + carboplatin + paclitaxel + radiotherapy (Arm 2); or durvalumab Q4W + carboplatin or cisplatin + pemetrexed + radiotherapy (non-squamous histology only; Arm 3). Patients received durvalumab until disease progression or unacceptable toxicity. The primary endpoint was safety and tolerability. RESULTS: Sixty-four patients were enrolled: 21, 22, and 21 in Arms 1, 2, and 3, respectively. One patient in Arm 1 had DLT (grade 3 aspartate aminotransferase increase and grade 4 alanine aminotransferase increase); no DLTs were observed in Arms 2 or 3. Grade 3/4 adverse events occurred in 76.6 % of patients overall; the most common were neutropenia (51.6 %), leukopenia (20.3 %), and anemia (17.2 %). In a post-hoc analysis, 7.8 % of patients had grade 3 pneumonitis/radiation pneumonitis (grouped term) events. Overall, the objective response rate was 60.9 % (95 % confidence interval [CI], 47.9-72.9); median duration of response was 15.8 months (95 % CI, 9.0-not estimable [NE]). Median progression-free survival was 13.4 months (95 % CI, 8.8-20.1) and median overall survival was not reached (95 % CI, 21.9-NE). CONCLUSION: Durvalumab in combination with cCRT was well tolerated, with a manageable safety profile and showed encouraging antitumor activity in patients with unresectable, stage III NSCLC.

Feasibility of 5-fluorouracil and imiquimod for the topical treatment of cervical intraepithelial neoplasias (CIN) 2/3.

OBJECTIVES: To determine the feasibility (as measured by tolerability and safety) and efficacy of topical 5-fluorouracil (5-FU) and imiquimod for the treatment of cervical intraepithelial neoplasia (CIN) 2/3. METHODS: This pilot prospective study was conducted in women aged 18-45 years with p16+ CIN 2/3. Participants underwent an 8-week alternating regimen of self-applied 5% 5-FU on weeks 1, 3, 5, and 7 and physician-applied imiquimod on weeks 2, 4, 6, and 8. Adverse events (AEs) were collected by symptom diary and clinical exam. Feasibility was measured by tolerability and safety (AEs) of the study intervention. Tolerability was assessed as the number of participants able to apply 50% or more of the treatment doses. The safety outcome was calculated as the number of participants who experienced "specified AEs" defined as possibly, probably, or definitely related grade 2 or worse AE or grade 1 genital AEs (blisters, ulcerations, or pustules) lasting more than 5 days. The efficacy of the intervention was determined by histology and high-risk human papillomavirus (hrHPV) testing was done after treatment. RESULTS: The median age of the 13 participants was 27 ± 2.9 years. Eleven (84.61%) participants applied 50% or more of the treatment. All participants reported grade 1 AEs; 6 (46.15%) reported grade 2 AEs; and 0 reported grade 3/4 AEs. Three (23.08%) participants had specified AEs. Histologic regression to normal or CIN 1 among those completing 50% or more of the treatment doses was observed in 10 (90.91%) participants, and 7 (63.63%) tested negative for hr-HPV at the end of the study. CONCLUSIONS: Topical treatment for CIN 2/3 with 5-FU/imiquimod is feasible, with preliminary evidence of efficacy. Topical therapies need further investigation as adjuncts or alternatives to surgical therapy for CIN 2/3.

Randomized Phase II Trial of Ficlatuzumab With or Without Cetuximab in Pan-Refractory, Recurrent/Metastatic Head and Neck Cancer.

PURPOSE: Primary or acquired resistance to cetuximab, an antiepidermal growth factor receptor monoclonal antibody (mAb), minimizes its utility in recurrent/metastatic head and neck squamous cell carcinoma (HNSCC). Aberrant hepatocyte growth factor/cMet pathway activation is an established resistance mechanism. Dual pathway targeting may overcome resistance. PATIENTS AND METHODS: This multicenter, randomized, noncomparative phase II study evaluated ficlatuzumab, an antihepatocyte growth factor mAb, with or without cetuximab in recurrent/metastatic HNSCC. The primary end point was median progression-free survival (PFS); an arm met significance criteria if the lower bound of the 90% CI excluded the historical control of 2 months. Key eligibility criteria were HNSCC with known human papillomavirus (HPV) status, cetuximab resistance (progression within 6 months of exposure in the definitive or recurrent/metastatic setting), and resistance to platinum and anti-PD-1 mAb. Secondary end points included objective response rate (ORR), toxicity, and the association of HPV status and cMet overexpression with efficacy. Continuous Bayesian futility monitoring was used. RESULTS: From 2018 to 2020, 60 patients were randomly assigned and 58 were treated. Twenty-seven versus 33 patients were allocated to monotherapy versus combination. Arms were balanced for major prognostic factors. The monotherapy arm closed early for futility. The combination arm met prespecified significance criteria with a median PFS of 3.7 months (lower bound 90% CI, 2.3 months; P = .04); the ORR was 6 of 32 (19%), including two complete and four partial responses. Exploratory analyses were limited to the combination arm: the median PFS was 2.3 versus 4.1 months (P = .03) and the ORR was 0 of 16 (0%) versus 6 of 16 (38%; P = .02) in the HPV-positive versus HPV-negative subgroups, respectively. cMet overexpression was associated with reduced hazard of progression in HPV-negative but not HPV-positive disease (P interaction = .02). CONCLUSION: The ficlatuzumab-cetuximab arm met significance criteria for PFS and warrants phase III development. HPV-negative HNSCC merits consideration as a selection criterion.

Integrating Immunotherapy into Multimodal Treatment of Head and Neck Cancer.

Patients with locally advanced head and neck squamous cell carcinoma (HNSCC) have a poor prognosis, with a significant risk of progression or death despite multimodal treatment with surgery, chemotherapy, and radiotherapy. Immune checkpoint inhibitors targeting the programmed death receptor-1 (PD1) have dramatically changed the treatment landscape for recurrent/metastatic disease, improving overall survival in both the first- and second-line palliative settings. This success has driven the investigation of treatment strategies incorporating immunotherapy earlier into the multimodal curative-intent or salvage treatment of both locally advanced and recurrent/metastatic HNSCC. This review encompassed the following three subjects, with a focus on recently reported and ongoing clinical trials: (1) the use of neoadjuvant immunotherapy prior to surgery for locally advanced HNSCC, (2) the use of immunochemoradiotherapy for locally advanced head and neck cancers, and (3) novel uses of immunotherapy in the salvage of recurrent/metastatic HNSCC via a combined modality, including reirradiation paradigms. The results of these studies are eagerly awaited to improve patient outcomes in this challenging disease.

A Phase 2, Double-blind, Randomized Controlled Trial of PROSTVAC in Prostate Cancer Patients on Active Surveillance.

BACKGROUND: There is an unmet clinical need for interventions to prevent disease progression in patients with localized prostate cancer on active surveillance (AS). OBJECTIVE: To determine the immunologic response to the PROSTVAC vaccine and the clinical indicators of disease progression in patients with localized prostate cancer on AS. DESIGN, SETTING, AND PARTICIPANTS: This was a phase 2, double-blind, randomized controlled trial in 154 men with low- or intermediate-risk prostate cancer on AS. INTERVENTION: Participants were randomized (2:1) to receive seven doses of subcutaneous PROSTVAC, a vaccinia/fowlpox viral vector-based immunotherapy containing a prostate-specific antigen (PSA) transgene and three T-cell co-stimulatory molecules, or an empty fowlpox vector (EV) over 140 d. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: The primary outcome was the change from baseline in CD4 and CD8 T-cell infiltration in biopsy tumor tissue. Key secondary outcomes were safety and changes in prostate biopsy tumor pathology, peripheral antigen-specific T cells, and serum PSA. Continuous variables were compared using nonparametric tests. Categorical variables were compared using Fisher's exact test. RESULTS AND LIMITATIONS: The PROSTVAC/EV vaccination was well tolerated. All except one participant completed the vaccination series. Changes in CD4 or CD8 density in biopsy tumor tissue did not differ between the PROSTVAC and EV arms. The proportions of patients with Gleason upgrading to grade group 3 after treatment was similar between the arms. There were no differences in postvaccination peripheral T-cell responses or the PSA change from baseline to 6-mo post-treatment follow-up between the groups. CONCLUSIONS: In this first-of-kind trial of immunotherapy in patients on AS for prostate cancer, PROSTVAC did not elicit more favorable prostate tissue or peripheral T-cell responses than the EV. There was no difference between the arms in clinicopathologic effects. Despite the null findings, this is the first study reporting the feasibility and acceptability of an immunotherapy intervention in the AS setting. PATIENT SUMMARY: We looked at responses after an experimental prostate cancer vaccine in patients with prostate cancer on active surveillance (AS). Participants who received the vaccine did not show more favorable outcomes than those receiving the control. Despite these findings, this is the first report showing the feasibility and acceptability of immunotherapy for prostate cancer in patients on AS.

Immunotherapy and Biomarker Testing in Recurrent and Metastatic Head and Neck Cancers: ASCO Guideline.

PURPOSE: To provide evidence-based recommendations for practicing physicians and other health care providers on immunotherapy and biomarker testing for head and neck cancers. METHODS: ASCO convened an Expert Panel of medical oncology, surgical oncology, radiation oncology, radiology, pathology, and patient advocacy experts to conduct a literature search, including systematic reviews, meta-analyses, randomized controlled trials, and prospective and retrospective comparative observational studies published from 2000 through 2022. Outcomes of interest included survival, overall response, and locoregional control. Expert Panel members used available evidence and informal consensus to develop evidence-based guideline recommendations. RESULTS: The literature search identified 28 relevant studies to inform the evidence base for this guideline. RECOMMENDATIONS: When possible, evidence-based recommendations were developed to address biomarker testing, first-line treatment regimens based on programmed death ligand-1 scores, immunotherapy in platinum-refractory recurrent or metastatic head and neck squamous cell carcinoma, immunotherapy in nasopharyngeal carcinoma, and radiation therapy in combination with immunotherapy for treatment of local recurrence.Additional information is available at www.asco.org/head-neck-cancer-guidelines.

c-Met Signaling as a Therapeutic Target in Head and Neck Cancer.

ABSTRACT: Despite a dearth of activating driver mutations in head and neck squamous cell carcinoma (HNSCC), aberrant activation of the oncogenes, epidermal growth factor receptor (EGFR), and c-Met is near-universal in human papillomavirus (HPV)-negative disease. Although EGFR activation drove the successful development of the anti-EGFR monoclonal antibody cetuximab in HNSCC, no c-Met-targeting therapy has gained regulatory approval. Inhibition of the c-Met pathway may subvert oncogenesis within the tumor-intrinsic compartment, blocking tumoral proliferation, invasion, migration, and metastasis, or the tumor-extrinsic compartment, modulating the immunosuppressive tumor microenvironment. This review discusses the rationale and current drug development strategies for targeting c-Met or its exclusive ligand hepatocyte growth factor (HGF) in HNSCC.

Safety, tolerability and efficacy of agonist anti-CD27 antibody (varlilumab) administered in combination with anti-PD-1 (nivolumab) in advanced solid tumors.

BACKGROUND: Phase 1/2 dose-escalation and expansion study evaluating varlilumab, a fully human agonist anti-CD27 mAb, with nivolumab in anti-PD-1/L1 naïve, refractory solid tumors. METHODS: Phase 1 evaluated the safety of varlilumab (0.1-10 mg/kg) with nivolumab (3 mg/kg) administered once every 2 weeks. Phase 2 evaluated varlilumab regimens (3 mg/kg once every 2 weeks, 3 mg/kg once every 12 weeks, and 0.3 mg/kg once every 4 weeks) with nivolumab 240 mg once every 2 weeks in tumor-specific cohorts. Primary objective was safety; key clinical endpoints included objective response rate (ORR) and overall survival rate at 12 months (OS12) (glioblastoma (GBM) only). Exploratory objectives included determination of effects on peripheral blood and intratumoral immune signatures. RESULTS: 175 patients were enrolled (36 in phase 1 and 139 in phase 2). Phase 1 dose-escalation proceeded to the highest varlilumab dose level without determining a maximum tolerated dose. In phase 2, ORR were ovarian 12.5%, squamous cell carcinoma of the head and neck 12.5%, colorectal cancer 5%, and renal cell carcinoma 0%; GBM OS12 was 40.9%. Increased tumor PD-L1 and intratumoral T cell infiltration were observed in ovarian cancer patients, with increases of ≥5% associated with better progression-free survival. The most common treatment related adverse events were fatigue (18%), pruritus (16%), and rash (15%). CONCLUSION: Varlilumab and nivolumab were well tolerated, without significant toxicity beyond that expected for each agent alone. Clinical activity was observed in patients that are typically refractory to anti-PD-1 therapy, however, overall was not greater than expected for nivolumab monotherapy. Treatment was associated with proinflammatory changes in the tumor microenvironment, particularly in ovarian cancer where the changes were associated with better clinical outcomes. TRIAL REGISTRATION NUMBER: NCT02335918.

STAT3 Activation as a Predictive Biomarker for Ruxolitinib Response in Head and Neck Cancer.

PURPOSE: Increased activity of STAT3 is associated with progression of head and neck squamous cell carcinoma (HNSCC). Upstream activators of STAT3, such as JAKs, represent potential targets for therapy of solid tumors, including HNSCC. In this study, we investigated the anticancer effects of ruxolitinib, a clinical JAK1/2 inhibitor, in HNSCC preclinical models, including patient-derived xenografts (PDX) from patients treated on a window-of-opportunity trial. EXPERIMENTAL DESIGN: HNSCC cell lines were treated with ruxolitinib, and the impact on activated STAT3 levels, cell growth, and colony formation was assessed. PDXs were generated from patients with HNSCC who received a brief course of neoadjuvant ruxolitinib on a clinical trial. The impact of ruxolitinib on tumor growth and STAT3 activation was assessed. RESULTS: Ruxolitinib inhibited STAT3 activation, cellular growth, and colony formation of HNSCC cell lines. Ruxolitinib treatment of mice bearing an HNSCC cell line-derived xenograft significantly inhibited tumor growth compared with vehicle-treated controls. The response of HNSCC PDXs derived from patients on the clinical trial mirrored the responses seen in the neoadjuvant setting. Baseline active STAT3 (pSTAT3) and total STAT3 levels were lower, and ruxolitinib inhibited STAT3 activation in a PDX from a patient whose disease was stable on ruxolitinib, compared with a PDX from a patient whose disease progressed on ruxolitinib and where ruxolitinib treatment had minimal impact on STAT3 activation. CONCLUSIONS: Ruxolitinib exhibits antitumor effects in HNSCC preclinical models. Baseline pSTAT3 or total STAT3 levels in the tumor may serve as predictive biomarkers to identify patients most likely to respond to ruxolitinib.

Clinical Study of Aspirin and Zileuton on Biomarkers of Tobacco-Related Carcinogenesis in Current Smokers.

The chemopreventive effect of aspirin and other non-steroidal anti-inflammatory drugs (NSAIDs) on lung cancer risk is supported by epidemiologic and preclinical studies. Zileuton, a 5-lipoxygenase inhibitor, has additive activity with NSAIDs against tobacco carcinogenesis in preclinical models. We hypothesized that cyclooxygenase plus 5-lipoxygenase inhibition would be more effective than a placebo in modulating the nasal epithelium gene signatures of tobacco exposure and lung cancer. We conducted a randomized, double-blinded study of low-dose aspirin plus zileuton vs. double placebo in current smokers to compare the modulating effects on nasal gene expression and arachidonic acid metabolism. In total, 63 participants took aspirin 81 mg daily plus zileuton (Zyflo CR) 600 mg BID or the placebo for 12 weeks. Nasal brushes from the baseline, end-of-intervention, and one-week post intervention were profiled via microarray. Aspirin plus zilueton had minimal effects on the modulation of the nasal or bronchial gene expression signatures of smoking, lung cancer, and COPD but favorably modulated a bronchial gene expression signature of squamous dysplasia. Aspirin plus zileuton suppressed urinary leukotriene but not prostaglandin E2, suggesting shunting through the cyclooxygenase pathway when combined with 5-lipoxygenase inhibition. Continued investigation of leukotriene inhibitors is needed to confirm these findings, understand the long-term effects on the airway epithelium, and identify the safest, optimally dosed agents.

A Multicenter Randomized Phase II Study of Single Agent Efficacy and Optimal Combination Sequence of Everolimus and Pasireotide LAR in Advanced Thyroid Cancer.

PURPOSE: Aberrant mTOR pathway and somatostatin receptor signaling are implicated in thyroid cancer and offer potential therapeutic targets. We assessed the clinical efficacy of everolimus and Pasireotide long-acting release (LAR) in radioiodine-refractory differentiated thyroid cancer (DTC) and medullary thyroid cancer (MTC). PATIENTS AND METHODS: Adults with progressive MTC and DTC untreated or treated with no more than one systemic agent were eligible. The trial was designed to establish the most promising regimen and the optimal combination sequence. Patients were randomized to start treatment with single agent everolimus (10 mg QD; Arm A), pasireotide-LAR (60 mg intramuscular injection, Q4 weeks; Arm B), or the combination (Arm C). At initial progression (PFS1), patients on Arm A or B switched to the combination and continued until progression (PFS2). Efficacy was measured by RECIST criteria. RESULTS: Study enrolled 42 patients: median age 65 years; female 17 (40.5%); White 31 (73.8%), African American 6 (14.3%), others 5 (11.9); DTC 32 (76.2%); MTC 10 (23.8%). There was no objective response by RECIST criteria across the three arms. Median and 1-year PFS1 rates were 8.3, 1.8, 8.1 months and 49.9%, 36.4%, 25.0% for Arms A, B, C, respectively. Median and 1-year PFS2 rates were 26.3, 17.5, 8.1 months and 78.4%, 70.0%, 25% for Arms A, B, C, respectively. The most frequent adverse events were anemia, stomatitis, fatigue, hyperglycemia, and hypercholesterolemia. CONCLUSIONS: The combination of everolimus and pasireotide-LAR showed promising efficacy over single agent. The delayed combination of everolimus and pasireotide-LAR following progression on single agent everolimus appeared intriguing as a combination strategy.

Precision medicine: Sustained response to erdafitinib in FGFR2-mutant, multiply recurrent ameloblastoma.

BACKGROUND: Ameloblastoma imposes significant morbidity and high-recurrence rates following surgery and radiation therapy. Although 89% of cases harbor oncogenic mutations, the role of targeted therapy is undefined. CASE: We describe a case of a 40-year-old male with multiply recurrent, locally invasive ameloblastoma of the posterior maxillary ridge. The tumor was unresectable for negative margins due to extensive intracranial disease, and the patient suffered severe symptoms including pain. Immune and genomic profiling were obtained to guide systemic treatment, showing a PD-L1 score of 2% and FGFR2V395D and SMOW535L mutations. The patient progressed rapidly on anti-PD1 immunotherapy. He was treated with the FGFR inhibitor, erdafitinib, with excellent partial response including resolution of intracranial disease and cancer-related pain, ongoing 2 years after drug initiation. CONCLUSION: Targeting the FGFR2 mutation resulted in sustained response and improved quality of life. Genomic profiling with targeted therapy for ameloblastoma appears promising, especially when surgery is technically infeasible.

Randomized Crossover Trial Evaluating Detoxification of Tobacco Carcinogens by Broccoli Seed and Sprout Extract in Current Smokers.

Consumption of cruciferous vegetables, rich in the isothiocyanate glucoraphanin, is associated with reduced risk of tobacco-related cancers. Sulforaphane, released by hydrolysis of glucoraphanin, potently induces cytoprotective phase II enzymes. Sulforaphane decreased the incidence of oral cancer in the 4NQO carcinogenesis model. In residents of Qidong, China, broccoli seed and sprout extracts (BSSE) increased detoxification of air pollutants benzene and acrolein, also found in tobacco smoke. This randomized, crossover trial evaluated detoxification of tobacco carcinogens by the BSSE Avmacol® in otherwise healthy smokers. Participants were treated for 2 weeks with both low and higher-dose BSSE (148 µmol vs. 296 µmol of glucoraphanin daily), separated by a 2-week washout, with randomization to low-high vs. high-low sequence. The primary endpoint was detoxification of benzene, measured by urinary excretion of its mercapturic acid, SPMA. Secondary endpoints included bioavailability, detoxification of acrolein and crotonaldehyde, modulation by GST genotype, and toxicity. Forty-nine participants enrolled, including 26 (53%) females with median use of 20 cigarettes/day. Low and higher-dose BSSE showed a mean bioavailability of 11% and 10%, respectively. Higher-dose BSSE significantly upregulated urinary excretion of the mercapturic acids of benzene (p = 0.04), acrolein (p < 0.01), and crotonaldehyde (p = 0.02), independent of GST genotype. Retention and compliance were high resulting in early study completion. In conclusion, BSSE significantly upregulated detoxification of the tobacco carcinogens benzene, acrolein, and crotonaldehyde in current tobacco smokers.

Phase II Trial of CDX-3379 and Cetuximab in Recurrent/Metastatic, HPV-Negative, Cetuximab-Resistant Head and Neck Cancer.

In phase I development, CDX-3379, an anti-ErbB3 monoclonal antibody, showed promising molecular and antitumor activity in head and neck squamous cell carcinoma (HNSCC), alone or in combination with cetuximab. Preliminary biomarker data raised the hypothesis of enhanced response in tumors harboring FAT1 mutations. This phase II, multicenter trial used a Simon 2-stage design to investigate the efficacy of CDX-3379 and cetuximab in 30 patients with recurrent/metastatic, HPV-negative, cetuximab-resistant HNSCC. The primary endpoint was objective response rate (ORR). Secondary endpoints included ORR in patients with somatic FAT1 mutations, progression-free survival (PFS), overall survival (OS), and safety. Thirty patients were enrolled from March 2018 to September 2020. The ORR in genomically unselected patients was 2/30 (6.7%; 95% confidence interval [CI], 0.8-22.1). Median PFS and OS were 2.2 (95% CI: 1.3-3.6) and 6.6 months (95% CI: 2.7-7.5), respectively. Tissue was available in 27 patients including one of two responders. ORR was 1/10 (complete response; 10%; 95% CI 0.30-44.5) in the FAT1-mutated versus 0/17 (0%; 95% CI: 0-19.5) in the FAT1-wildtype cohorts. Sixteen patients (53%) experienced treatment-related adverse events (AEs) ≥ grade 3. The most common AEs were diarrhea (83%) and acneiform dermatitis (53%). Dose modification was required in 21 patients (70%). The modest ORR coupled with excessive, dose-limiting toxicity of this combination precludes further clinical development. Dual ErbB3-EGFR inhibition remains of scientific interest in HPV-negative HNSCC. Should more tolerable combinations be identified, development in an earlier line of therapy and prospective evaluation of the FAT1 hypothesis warrant consideration.

Targeted CUL4A inhibition synergizes with cisplatin to yield long-term survival in models of head and neck squamous cell carcinoma through a DDB2-mediated mechanism.

Patients with late-stage and human papillomavirus (HPV)-negative head and neck squamous cell carcinoma (HNSCC) continue to have a very poor prognosis. The development of more effective novel therapies that improve overall survival and overcome drug resistance is an urgent priority. Here we report that HNSCC tumors significantly overexpress NEDD8 and exhibit high sensitivity to the first-in-class NEDD8-activating enzyme (NAE) inhibitor pevonedistat. Additional studies established that disruption of NEDD8-mediated protein turnover with pevonedistat dramatically augmented cisplatin-induced DNA damage and apoptosis in HNSCC models. Further analysis revealed that the specific pevonedistat target CUL4A played an essential role in driving the synergy of the pevonedistat and cisplatin combination. Targeted inhibition of CUL4A resulted in significant downregulation in Damage Specific DNA binding protein 2 (DDB2), a DNA-damage recognition protein that promotes nucleotide excision repair and resistance to cisplatin. Silencing of CUL4A or DDB2 enhanced cisplatin-induced DNA damage and apoptosis in a manner similar to that of pevonedistat demonstrating that targeted inhibition of CUL4A may be a novel approach to augment cisplatin therapy. Administration of pevonedistat to mice bearing HNSCC tumors significantly decreased DDB2 expression in tumor cells, increased DNA damage and potently enhanced the activity of cisplatin to yield tumor regression and long-term survival of all animals. Our findings provide strong rationale for clinical investigation of CUL4A inhibition with pevonedistat as a novel strategy to augment the efficacy of cisplatin therapy for patients with HNSCC and identify loss of DDB2 as a key pharmacodynamic mediator controlling sensitivity to this regimen.