Prognostic value of CRTC1-MAML2 translocation in salivary mucoepidermoid carcinoma: Systematic review and meta-analysis.

The presence of the CRTC1-MAML2 translocation has been described in mucoepidermoid carcinoma (MEC) as a predictor of better survival rates. However, the real prognostic value of the translocation has been debated due to recent controversial findings. The aim of this study was to perform a systematic review to understand the prognostic potential of the CRTC1-MAML2 translocation in MEC. An electronic search was carried out using the MEDLINE/PubMed, EMBASE and Scopus databases. Articles that assessed the association between the CRTC1-MAML2 translocation and survival of MEC patients were selected for the systematic review. Ten published articles were included in the qualitative synthesis. The prevalence of the translocation varied from 33.7% to 69.7%. Seven studies observed a significant association between the presence of the CRTC1-MAML2 translocation and a favourable clinical outcome, which could improve disease-free, disease-specific or overall survival. Five studies were included in the quantitative synthesis. Fixed-effects model confirmed that translocation-positive patients have a decreased risk of death (combined odds ratio 0.08, 95% confidence interval - 0.03-0.23, P < .00001). The detection of the CRTC1-MAML2 translocation appears to be useful as a prognostic factor in MEC. However, the level of evidence is not as high as it could be once important limitations were found in the published studies.

Malignant transformation of craniomaxillofacial fibro-osseous lesions: A systematic review.

The purpose of this study was to perform a systematic review of the literature concerning all documented cases of malignant transformation of craniomaxillofacial fibro-osseous lesions (FOLs). Three electronic databases were searched. Data were evaluated descriptively. Kaplan-Meier survival curves were constructed and compared using the log-rank test. A critical appraisal of included articles was performed through the Joanna Briggs Institute tool. A total of 19 studies including 27 patients were selected for data extraction. Twenty-six cases were initially diagnosed as fibrous dysplasia and one as ossifying fibroma. The mean age at the time of malignant transformation was 38.11 years, and the average time from initial diagnosis to malignant transformation was 18.2 years. The male:female ratio was 1:1.2, and the maxilla:mandible ratio was 1.5:1. The histological type of the malignant tumor was predominantly osteosarcoma. Follow-up was available for 21 patients. The 3-year overall survival rate was 51%. Mandible tumors and diagnoses other than osteosarcoma tended to have poor survival rates, but no significant difference was identified. We concluded that between all FOLs, only fibrous dysplasia seems to have a considerable increased risk of malignant transformation. Thus, a regular and long follow-up period is advised.

Hypoacetylation of acetyl-histone H3 (H3K9ac) as marker of poor prognosis in oral cancer.

AIMS: Epigenetics refers to changes in cell characteristics that occur independently of modifications to the DNA sequence. Oral carcinogenesis is influenced by modifications in epigenetic mechanisms, including changes in histones, which are proteins that support chromatin remodelling for the dynamic regulation of gene expression and silencing. The dysregulation of histone acetylation can lead to the uncontrolled activity of different genes, thereby triggering events associated with malignant transformation. The aim of this study was to analyse the expression of acetyl-histone H3 at lys9 (H3K9ac) in oral leucoplakia (OL) and oral squamous cell carcinoma (OSCC) in addition to its association with cell proliferation, epithelial-mesenchymal transition (EMT) and clinical-pathological findings. METHODS AND RESULTS: Samples of normal oral mucosa (NOM), OL and OSCC were submitted to immunohistochemical analysis using anti-H3K9ac, Ki67 and vimentin. Slides were submitted to quantitative analysis regarding the percentage of positive cells. OSCC presented less expression of H3K9ac in comparison to OL (P < 0.01), whereas Ki67 and vimentin levels increased from OL to OSCC (P < 0.001 and P = 0.03, respectively). OSCC patients with poor prognosis had less H3K9ac expression (P = 0.04). The Kaplan-Meier cumulative survival curves also revealed lower survival rates in patients with less H3K9ac expression (P < 0.01). CONCLUSIONS: The present findings suggest that changes in H3K9ac occur during the process of oral carcinogenesis along with an increase in cell proliferation and EMT. The results demonstrate that H3K9ac may be a useful novel prognostic marker for OSCC.

New photobiomodulation protocol prevents oral mucositis in hematopoietic stem cell transplantation recipients-a retrospective study.

Oral mucositis (OM) is an adverse side effect among hematopoietic stem cell transplantation (HSCT) recipients. The objective of this retrospective study was to evaluate the preventive effect of photobiomodulation (PBM) applied three times per week versus seven times per week in patients undergoing HSCT. The risk factors related to the incidence and severity of OM were also assessed. This was a retrospective study that evaluated 99 HSCT recipients who received different PBM protocols. Group I received three sessions per week, and group II received daily treatment. PBM was applied using a continuous-wave diode laser (InGaAlP; MM Optics, São Carlos, SP, Brazil) at a wavelength of 660 nm (visible-red) and a total radiant energy of 0.24 J per point. The baseline disease, type of transplant, type of conditioning, prophylaxis against graft-versus-host disease, OM grade, absolute leukocyte and platelet counts, and levels of liver and renal function markers were collected from medical records. The patients' age ranged from 13 to 71 years (mean/SD, 40.54 ± 16.45). No significant difference was observed between groups I and II regarding sex, age, ethnic, diagnosis, donor type, and conditioning treatment. Both PBM protocols were equally efficient in preventing OM (p = 0.34, ANOVA). Independent of the PBM protocol used, patients who received allogeneic transplant (p < 0.01-Fischer's exact test), total body irradiation (TBI-12Gy) (p = 0.01-chi-square test), busulfan + cyclophosphamide (p < 0.01-chi-square test), or methotrexate-containing regimens (p < 0.01-Fischer's exact test) demonstrated higher OM incidence and severity. Myelosuppression (p < 0.01-Mann-Whitney test) and impaired renal function (p = 0.02-Mann-Whitney test) were also considered risk factors for OM. Based on this retrospective data, PBM was effective in preventing OM in patients undergoing HSCT even when it was applied three times a week. A prospective study might be necessary to confirm these findings.

Gingival Cysts of Adults: Retrospective Analysis from Two Centers in South Brazil and a Review of the Literature.

Gingival cysts of adults are rare developmental cysts, with an incidence of 0.3% among all odontogenic cysts. They are benign, well-defined nodules located on the attached gingiva with a fluid-filled appearance. The aim of the present study was to perform an analysis of gingival cysts in adults diagnosed at an oral pathology laboratory and a hospital pathology service in order to determine the frequency of occurrence of this lesion, and to perform a literature review to correlate the present findings with those described in the literature. This study emphasizes the low frequency of gingival cysts in adults and the importance of gathering clinical, radiographic and histopathological information to define the final diagnosis.

Thyroid Incidentalomas: Scrutinizing the Mode of Detection and Evaluating its Contribution to Thyroid Cancer Diagnosis.

There is an ongoing debate about the reasons behind the increasing incidence of thyroid cancer in the last two to three decades. Here, we investigate how thyroid nodules were detected in a large series of consultations for thyroid nodular pathology. METHODS: In total, 576 patients were analyzed, with a total of 1014 nodules described. RESULTS: In 347 (60.2%) cases, the diagnosis of a thyroid nodule was incidental, mostly during imaging tests for other reasons. Incidental diagnosis occurred among all ranges of nodule diameter and between palpable and non-palpable cases, even within a small proportion of symptomatic cases. In univariate analysis, incidental diagnosis was associated with smaller nodule diameter, non-palpable nodules, asymptomatic cases, older patient age, less advanced stages (T1-2), and conservative management. After multivariate analysis, older age, euthyroidism, and smaller diameter were statistically significant. Incidental diagnosis contributed to the diagnosis of 53.8% of the cases of cancer. Advanced T stages (T3-4) were more common in non-incidental diagnoses. CONCLUSION: Our results indicate that incidental diagnosis of thyroid nodules is a significant contributor to thyroid cancer diagnosis in all ranges of nodule diameter, especially at earlier stages.

Social networking website increases efficacy and engagement in a distance learning course about oral lesions.

PURPOSE: Distance learning appears to be an attractive approach to continuing education courses, but one barrier is maintaining learner engagement throughout the course. The primary aim of this research was to evaluate the operational efficacy of a private Facebook™ group (FG) in serving as a support mechanism for distance learning courses, and its impact on three fundamental dimensions: the attrition rates of participants who did not complete the course (commonly referred to as dropout rates), the rates of course completion and approval, and the overall performance of the participants. METHODS: The participants of this quasi-experimental study comprised 159 dental students and 565 dentists enrolled in an e-learning course on oral mucosal lesion diagnosis. Prior to the initiation of the course, all participants were provided with the option to join a private FG. Within this group, moderators shared motivational messages and provided reminders concerning deadlines. Moreover, participants had the opportunity to engage in interactive discussions pertaining to topics related to the course. The course itself followed a self-guided format, employing the flipped-classroom methodology, spanning a total of 50 instructional hours. In order to assess the effectiveness of the course, participants were presented with photographs illustrating 30 oral lesions and were asked to propose diagnostic hypotheses both before and after the educational intervention (pre-tests and post-tests). RESULTS: Dentists who participated in the FG exhibited a significantly lower rate of discontinuation. As for dental students, their involvement in the group was positively associated with better performance, as determined by the percentage of accurate diagnostic hypotheses (a minimum of 70% correct responses was required for their approval in the course). CONCLUSIONS: Facebook™ demonstrates promise as a supplementary pedagogical tool in distance education courses. The interactive nature of the platform has the potential to alleviate the inherent challenges of remote learning.

Impact of AJCC 8 pT staging in cutaneous head and neck squamous cell carcinoma in a nonselected real-world patient sample.

OBJECTIVE: Our aim was to evaluate characteristics associated with worse survival and the effectiveness of AJCC 8 in a real-world cohort of HNCSCC from South Brazil. METHODS: A 10-year retrospective cohort study (2011-2020) at a tertiary care center comprising 647 HNCSCC excised from 435 patients. RESULTS: At multivariable analysis, ear/nose/zygomatic or periorbital site, compromised or exiguous margins, and advanced pT stage were independent factors associated to DFS, while age, pN, and loco-regional recurrence were independent factors associated to DSS. Cox-regression multivariable models showed that the pT stage was statistically significant for the DFS, but not DSS. A significant distinction was only observed between T1 and T2. CONCLUSION: It was only in the lower categories of AJCC 8 (T1 and T2) that we were able to demonstrate the ability to stratify tumors with a significant risk of poor disease-related outcomes.

MYB-NFIB fusion transcript in adenoid cystic carcinoma: Current state of knowledge and future directions.

Adenoid cystic carcinoma (ACC) is the most common type of salivary gland cancer that can also arise in other primary sites. Regardless of the site, most ACC cases carry a recurrent chromosomal translocation - t(6;9)(q22-23;p23-24) - involving the MYB oncogene and the NFIB transcription factor. Generally, a long sequence of MYB is fused to the terminal exons of NFIB, yet the break can occur in different exons for both genes, resulting in multiple chimeric variants. The fusion status can be determined by a number of methods, each of them with particular advantages. In vitro and in vivo studies have been conducted to understand the biological consequences of MYB-NFIB translocation, and such findings could contribute to improving the current inefficient therapeutic options for disseminated ACC. This review provides a discussion on relevant evidence in the context of ACC MYB-NFIB translocations to determine the current state of knowledge and discuss future directions.

Periodontal disease affects oral cancer progression in a surrogate animal model for tobacco exposure.

For decades, the link between poor oral hygiene and the increased prevalence of oral cancer has been suggested. Most recently, emerging evidence has suggested that chronic inflammatory diseases from the oral cavity (e.g., periodontal disease), to some extent, play a role in the development of oral squamous cell carcinoma (OSCC). The present study aimed to explore the direct impact of biofilm­induced periodontitis in the carcinogenesis process using a tobacco surrogate animal model for oral cancer. A total of 42 Wistar rats were distributed into four experimental groups: Control group, periodontitis (Perio) group, 4­nitroquinoline 1­oxide (4­NQO) group and 4NQO/Perio group. Periodontitis was stimulated by placing a ligature subgingivally, while oral carcinogenesis was induced by systemic administration of 4NQO in the drinking water for 20 weeks. It was observed that the Perio, 4NQO and 4NQO/Perio groups presented with significantly higher alveolar bone loss compared with that in the control group. Furthermore, all groups receiving 4NQO developed lesions on the dorsal surface of the tongue; however, the 4NQO/Perio group presented larger lesions compared with the 4NQO group. There was also a modest overall increase in the number of epithelial dysplasia and OSCC lesions in the 4NQO/Perio group. Notably, abnormal focal activation of cellular differentiation (cytokeratin 10­positive cells) that extended near the basal cell layer of the mucosa was observed in rats receiving 4NQO alone, but was absent in rats receiving 4NQO and presenting with periodontal disease. Altogether, the presence of periodontitis combined with 4NQO administration augmented tumor size in the current rat model and tampered with the protective mechanisms of the cellular differentiation of epithelial cells.

Can propranolol act as a chemopreventive agent during oral carcinogenesis? An experimental animal study.

The multistep process of oral carcinogenesis provides a biological rationale for the use of chemoprevention in individuals at increased risk of developing oral cancer. We aimed to determine if low doses of propranolol can prevent the development of oral cancer using a tobacco-relevant and p53-associated animal model of cancer initiation. Twenty-six Wistar rats were randomly allocated into two groups, vehicle, and propranolol. All animals received 4-nitroquinoline N-oxide (4NQO) at 25 ppm diluted in the drinking water for 20 weeks. Animals from the propranolol group received propranolol (0.1 mg/kg) 5 days per week by gavage for 18 weeks. The clinical analysis was performed by measuring the area of the lesion and assessment of scores based on lesion appearance (papule; plaque; nodule or ulcerated). Histopathological analysis was performed to determine the presence of epithelial dysplasia or invasive squamous cell carcinoma (SCC). The average lesion area in 4NQO + vehicle and in 4NQO + propranolol groups were 0.20 and 0.28 mm2, respectively (P = 0.53). The percentage of cases clinically graded as papules, thick plaques, nodular areas, and ulcerated lesions was similar between groups (P = 0.94). Histopathological diagnosis also did not differ between groups (P = 0.65), with 54.5 and 70% of cases being diagnosed as SCC in 4NQO and in 4NQO + propranolol groups, respectively. In conclusion, daily doses propranolol at 0.1 mg/kg were not as effective as a chemopreventive therapy in an animal model of 4NQO-induced carcinogenesis.

BDNF/TrkB/Akt Signaling Pathway Epithelial Odontogenic Tumors and Keratocyst: An Immunohistochemical Study Comparative With Dental Germs.

Odontogenic lesions (OL) are an important group of oral and maxillofacial diseases represented by odontogenic cysts, benign, and malignant tumors. The brain-derived neurotrophic factor (BDNF)/ tropomyosin receptor kinase B (TrkB) signaling pathway has multiple biological actions and has been identified as an important pathway in the proliferation, invasion, and survival of different epithelial tumors. Its role in the development of OL, however, has so far been unexplored. Our aim was to evaluate the BDNF/TrkB/Akt/p-RPS6 signaling pathway in OL of epithelial origin. This cross-sectional study comprised 3 cases of tooth germs, 25 cases of odontogenic keratocyst (OK), 29 cases of ameloblastoma (Am), and 6 cases of ameloblastic carcinoma. Immunohistochemical staining for BDNF, TrkB, p-Akt, and p-RPS6 was performed. OLs were evaluated according to the pattern of immunohistochemical expression in epithelial cells and by semiquantitative scores that considered the intensity of staining and percentage of positive cells. BDNF stromal expression was also assessed. No significant differences were observed with respect to the percentage of positive cases for all markers. Regarding the immunoreactive scores, BDNF and p-RPS6 expressions were similar in the odontogenic epithelium of all OL. However, TrkB and p-Akt were overexpressed in OK compared with ameloblastic carcinoma. In Am, epithelial BDNF was significantly higher compared with stromal expression. In conclusion, BDNF seems to participate in the development of cystic, benign, and malignant odontogenic epithelium to similar degrees. The acquisition of the invasive or malignant phenotype in odontogenic neoplasms is not associated with alterations in the BDNF/TrkB/Akt/RPS6 axis, which could be implicated in the differentiation process.

Curcuma longa L. Effects on Akt/mTOR Pathway and NF-κB Expression During Skin Wound Healing: An Immunohistochemical Study.

Skin ulcers, wounds, or burns represent a burden for health care worldwide. Our aim was to explore the effects of mucoadhesive formulation with Curcuma longa L. extract mucoadhesive formulation containing curcumin (MFC) on skin healing in Wistar rats. Fifty-four rats were randomly allocated into 3 groups: control, vehicle, and MFC. A full-thickness circular wound was induced on the back of each animal. Two daily applications of the products were performed according to the experimental group. On days 3, 10, and 21, 6 animals in each group were euthanized. Clinical analysis was based on wound area. Histologic analysis was performed in hematoxylin and eosin-stained sections, with re-epithelization and inflammation being assessed by means of semiquantitative scores. To analyze the Akt/mTOR pathway, immunohistochemistry for phospho Akt (pAkt) and phospho ribosomal protein S6 were investigated. In addition, nuclear factor kappa-light-chain-enhancer of activated B cells immunolabeling was performed. Clinical analysis revealed wounds with a smaller area on days 3 and 10 in curcumin-treated animals. Histologically, MFC had a significant impact on inflammatory events on days 3 and 10 and promoted faster re-epithelization, which was evidenced on day 10. MFC-treated wounds exhibited pAkt upregulation on day 10 and both pAkt and phospho ribosomal protein S6 downregulation on day 21. Nuclear factor kappa-light-chain-enhancer of activated B cells expression varied through the evaluation periods; however, no significant difference was observed between groups. Collectively, our results indicate that MFC is efficient in accelerating cutaneous wound repair through modulation of the inflammatory process and stimulus of re-epithelization by an Akt/mTOR-dependent mechanism.

Prevalence of p16 expression in oropharyngeal squamous cell carcinoma in southern Brazil.

OBJECTIVE: Our aim was to evaluate the prevalence of human papillomavirus (HPV)-positive tumors in a cohort of patients with oropharyngeal squamous cell carcinoma (OPSCC) at a single center in southern Brazil and determine the short-term prognostic factors in this sample. STUDY DESIGN: Ninety-one consecutive patients with newly diagnosed primary OPSCC between January 2017 and December 2019 were retrospectively included. Demographic, clinical, pathologic, and survival data were collected. HPV status was determined by using p16 immunohistochemistry. RESULTS: The overall prevalence of HPV-positive (HPV+) OPSCC was 20.9%. Patients with HPV+ tumors presented a nodal metastasis as the first clinical sign (P = .02); reported less alcohol (P < .001) and tobacco use (P < .001); exhibited lower tumor stages (P < .001) and higher microscopic grades (P = .01); and had higher chances of having resectable tumors (P = .008). p16-negative status (P = .01); unresectable/inoperable tumors (P < .001); presence of nodal metastasis (P = .005); and higher American Joint Committee on Cancer (AJCC) stage (P = .002) were significantly associated with worse disease-specific survival. CONCLUSIONS: The prevalence of HPV+ OPSCC in southern Brazil is relatively low, and p16-positive status was associated with Better prognosis. Higher AJCC stage, nodal metastasis, and unresectability/inoperability were associated with the highest hazard ratios for death resulting from OPSCC.

TrkB-Targeted Therapy for Mucoepidermoid Carcinoma.

The brain-derived neurotrophic factor (BDNF)/tyrosine receptor kinase B (TrkB) pathway was previously associated with key oncogenic outcomes in a number of adenocarcinomas. The aim of our study was to determine the role of this pathway in mucoepidermoid carcinoma (MEC). Three MEC cell lines (UM-HMC-2, H253 and H292) were exposed to Cisplatin, the TrkB inhibitor, ANA-12 and a combination of these drugs. Ultrastructural changes were assessed through transmission electron microscopy; scratch and Transwell assays were used to assess migration and invasion; and a clonogenic assay and spheroid-forming assay allowed assessment of survival and percentage of cancer stem cells (CSC). Changes in cell ultrastructure demonstrated Cisplatin cytotoxicity, while the effects of ANA-12 were less pronounced. Both drugs, used individually and in combination, delayed MEC cell migration, invasion and survival. ANA-12 significantly reduced the number of CSC, but the Cisplatin effect was greater, almost eliminating this cell population in all MEC cell lines. Interestingly, the spheroid forming capacity recovered, following the combination therapy, as compared to Cisplatin alone. Our studies allowed us to conclude that the TrkB inhibition, efficiently impaired MEC cell migration, invasion and survival in vitro, however, the decrease in CSC number, following the combined treatment of ANA-12 and Cisplatin, was less than that seen with Cisplatin alone; this represents a limiting factor.

Head and neck cancer patient-derived xenograft models - A systematic review.

BACKGROUND: Patient-derived xenograft (PDX) involve the direct surgical transfer of fresh human tumor samples to immunodeficient mice. This systematic review aimed to identify publications of head and neck cancer PDX (HNC-PDX) models, describing the main methodological characteristics and outcomes. METHODS: An electronic search was undertaken in four databases, including publications having used HNC-PDX. Data were analyzed descriptively. RESULTS: 63 articles were yielded. The nude mouse was one most commonly animal model used (38.8 %), and squamous cell carcinoma accounted for the majority of HNC-PDX (80.6 %). Tumors were mostly implanted in the flank (86.3 %), and the latency period ranged from 30 to 401 days. The successful rate ranged from 17 % to 100 %. Different drugs and pathways were identified. CONCLUSION: HNC-PDX appears to significantly recapitulate the morphology of the original HNC and represents a valuable method in translational research for the assessment of the in vivo effect of novel therapies for HNC.

Targeting histone deacetylase and NFκB signaling as a novel therapy for Mucoepidermoid Carcinomas.

Malignancies from the salivary glands are rare and represent 11% of all cancers from the oropharyngeal anatomical area. Mucoepidermoid Carcinomas (MEC) is the most common malignancy from the salivary glands. Low survival rates of high-grade Mucoepidermoid Carcinomas (MEC) are particularly associated with the presence of positive lymph nodes, extracapsular lymph node spread, and perineural invasion. Most recently, the presence of cancer stem cells (CSC), and the activation of the NFκB signaling pathway have been suggested as cues for an acquired resistance phenotype. We have previously shown that NFκB signaling is very active in MEC tumors. Herein, we explore the efficacy of NFκB inhibition in combination with class I and II HDAC inhibitor to deplete the population of CSC and to destroy MEC tumor cells. Our finding suggests that disruption of NFκB signaling along with the administration of HDAC inhibitors constitute an effective strategy to manage MEC tumors.

Immunohistochemical Study of TGF-ß1 in Oral Leukoplakia and Oral Squamous Cell Carcinoma: Correlations Between Clinicopathologic Factors and Overall Survival.

The aim of the present study was to analyze transforming growth factor ß1 (TGF-ß1) expression in cases of leukoplakia and oral squamous cell carcinoma (OSCC) and to correlate these expression profiles with proliferative labeling index, clinicopathologic factors, and clinical outcome. Clinical data for 24 cases of leukoplakia and 87 cases of OSCC were retrieved from medical records. OSCC tissues were included into tissue microarray blocks and sections of normal mucosa, leukoplakia, and OSCC tissue microarray's were prepared on slides. Immunohistochemistry was used to detect expression of TGF-ß1 and Ki67. The expression of TGF-ß1 and Ki67 were significantly increased from normal mucosa, through leukoplakia to OSCC. High expression of TGF-ß1 correlated with an increase in proliferative labeling index. No association between TGF-ß1 expression and the clinicopathologic factors examined was observed. Expression of TGF-ß1 also did not associate with clinical outcome in either of groups. Our results suggest that changes in TGF-ß1 are associated with the progression of oral carcinogenesis.

5T4-Targeted Therapy Ablates Cancer Stem Cells and Prevents Recurrence of Head and Neck Squamous Cell Carcinoma.

Purpose: Locoregional recurrence is a frequent treatment outcome for patients with advanced head and neck squamous cell carcinoma (HNSCC). Emerging evidence suggests that tumor recurrence is mediated by a small subpopulation of uniquely tumorigenic cells, that is, cancer stem cells (CSC), that are resistant to conventional chemotherapy, endowed with self-renewal and multipotency.Experimental Design: Here, we evaluated the efficacy of MEDI0641, a novel antibody-drug conjugate targeted to 5T4 and carrying a DNA-damaging "payload" (pyrrolobenzodiazepine) in preclinical models of HNSCC.Results: Analysis of a tissue microarray containing 77 HNSCC with follow-up of up to 12 years revealed that patients with 5T4high tumors displayed lower overall survival than those with 5T4low tumors (P = 0.038). 5T4 is more highly expressed in head and neck CSC (ALDHhighCD44high) than in control cells (non-CSC). Treatment with MEDI0641 caused a significant reduction in the CSC fraction in HNSCC cells (UM-SCC-11B, UM-SCC-22B) in vitro Notably, a single intravenous dose of 1 mg/kg MEDI0641 caused long-lasting tumor regression in three patient-derived xenograft (PDX) models of HNSCC. MEDI0641 ablated CSC in the PDX-SCC-M0 model, reduced it by five-fold in the PDX-SCC-M1, and two-fold in the PDX-SCC-M11 model. Importantly, mice (n = 12) treated with neoadjuvant, single administration of MEDI0641 prior to surgical tumor removal showed no recurrence for more than 200 days, whereas the control group had 7 recurrences (in 12 mice; P = 0.0047).Conclusions: Collectively, these findings demonstrate that an anti-5T4 antibody-drug conjugate reduces the fraction of CSCs and prevents local recurrence and suggest a novel therapeutic approach for patients with HNSCC. Clin Cancer Res; 23(10); 2516-27. ©2016 AACR.