HIV-1 mutants expressing B cell clonogenic matrix protein p17 variants are increasing their prevalence worldwide.

AIDS-defining cancers declined after combined antiretroviral therapy (cART) introduction, but lymphomas are still elevated in HIV type 1 (HIV-1)-infected patients. In particular, non-Hodgkin's lymphomas (NHLs) represent the majority of all AIDS-defining cancers and are the most frequent cause of death in these patients. We have recently demonstrated that amino acid (aa) insertions at the HIV-1 matrix protein p17 COOH-terminal region cause protein destabilization, leading to conformational changes. Misfolded p17 variants (vp17s) strongly impact clonogenic B cell growth properties that may contribute to B cell lymphomagenesis as suggested by the significantly higher frequency of detection of vp17s with COOH-terminal aa insertions in plasma of HIV-1-infected patients with NHL. Here, we expand our previous observations by assessing the prevalence of vp17s in large retrospective cohorts of patients with and without lymphoma. We confirm the significantly higher prevalence of vp17s in lymphoma patients than in HIV-1-infected individuals without lymphoma. Analysis of 3,990 sequences deposited between 1985 and 2017 allowed us to highlight a worldwide increasing prevalence of HIV-1 mutants expressing vp17s over time. Since genomic surveillance uncovered a cluster of HIV-1 expressing a B cell clonogenic vp17 dated from 2011 to 2019, we conclude that aa insertions can be fixed in HIV-1 and that mutant viruses displaying B cell clonogenic vp17s are actively spreading.

Hematologic cancers in individuals infected by HIV.

HIV infection increases cancer risk and is linked to cancers associated to infectious agents classified as carcinogenic to humans by the International Agency for Research on Cancer. Lymphomas represent one of the most frequent malignancies among individuals infected by HIV. Diffuse large B-cell lymphoma remains a leading cancer after the introduction of combined antiretroviral therapy (cART). The incidence of other lymphomas including Burkitt lymphoma, primary effusion lymphomas, and plasmablastic lymphoma of the oral cavity remain stable, whereas the incidence of Hodgkin lymphoma and Kaposi sarcoma-associated herpesvirus (KSHV)-associated multicentric Castleman disease has increased. The heterogeneity of lymphomas in individuals infected by HIV likely depends on the complexity of involved pathogenetic mechanisms (ie, HIV-induced immunosuppression, genetic abnormalities, cytokine dysregulation, and coinfection with the gammaherpesviruses Epstein-Barr virus and KSHV) and the dysregulation of the immune responses controlling these viruses. In the modern cART era, standard treatments for HIV-associated lymphoma including stem cell transplantation in relapsed/refractory disease mirror that of the general population. The combination of cART and antineoplastic treatments has resulted in remarkable prolongation of long-term survival. However, oncolytic and immunotherapic strategies and therapies targeting specific viral oncogenes will need to be developed.

HIV-related lymphomas.

PURPOSE OF REVIEW: To summarize the recent evidence on the pathology, current standard of care and recent advances in the treatment of HIV-related lymphomas. RECENT FINDINGS: Lymphomas remain a major cause of morbidity and mortality in people living with HIV, even in the era of combination antiretroviral therapy (cART). However, treatment outcomes for these malignancies have improved in recent decades, due to full-dose chemotherapy, effective cART and supportive care. Recent advances include the identification of novel driving signaling pathways as promising molecular targets to improve lymphoma outcomes. SUMMARY: Patients with HIV-related lymphomas who receive effective cART should be treated like the general population.

Prognostic significance of neutrophil-to-lymphocyte ratio in HPV status era for oropharyngeal cancer.

AIM: To evaluate the role of baseline neutrophil-to-lymphocyte ratio (NLR) as prognostic marker in squamous cell carcinoma of the oropharynx (OPC) treated with definitive chemoradiotherapy (CRT) in the era of HPV status. PATIENTS AND METHODS: A retrospective analysis of 125 patients (pts) affected with locally advanced OPC was performed. Inclusion criteria were age >18 years, stage III or IV (TNM 7th ed.) and definitive CRT. Haematological marker for their independent role as prognostic biomarkers for progression-free survival (PFS) and overall survival (OS). Logistic models were used to assess the association with downstage in TNM 8th ed. RESULTS: Seventy-seven (61.6%) pts had HPV/p16 + related OPC. Therapeutic choice consisted in sequential and concurrent CRT. Median follow-up was 50 months. A value of NLR ≥3 was associated with poorer OS. Two-year OS was 91% and 81% in pts with NLR <3 and ≥3, respectively. CONCLUSION: A baseline NLR ≥ 3 at treatment initiation represented a negative prognostic marker for OPC treated with definitive CRT. These results are in line with literature data, and prognostic value of NLR has been confirmed restaging our cohort with new TNM staging (8th ed.). Therefore, NLR could be considered a valuable biomarker for risk stratification in pts with OPC.

KSHV-associated multicentric Castleman disease: A tangle of different entities requiring multitarget treatment strategies.

Multicentric Castleman Disease (MCD) is a lymphoproliferative disorder presenting with heterogeneous pathological and clinical features. It comprises disease entities with a complex aetiology and overlapping pathogenesis. MCD can be found in association with HIV infection, plasma-cell dyscrasias, Kaposi sarcoma (KS), B-cell lymphomas including primary effusion lymphoma (PEL) and its solid variant, and Hodgkin lymphoma. In KSHV-associated MCD cases, a common association is KS and a specific variant of lymphoma referred to as "plasmablastic lymphoma," also called "large B-cell lymphoma arising in KSHV-associated MCD" lacking EBV infection. MCD is often referred to as human interleukin-6 (hIL-6) syndrome, since an overproduction of IL-6 occurs in MCD-associated diseases as well as in MCD itself. hIL-6 and a viral IL-6 (vIL-6) homolog encoded by KSHV can independently or together lead to flares of KSHV-associated MCD. Recently, a new clinical entity was proposed to describe a severe systemic infection/reactivation of KSHV: KSHV inflammatory syndrome (KICS). KICS may contribute in inducing the inflammatory symptoms seen in some patients with severe KS or PEL. The precise relationship of KICS to KSHV-associated MCD is unclear and it is possible that KICS may be prodromal symptoms to frank KSHV-associated MCD. Options for treatment of KSHV-associated MCD and related diseases include monoclonal antibodies, chemotherapy, immune modulators, virus-activated cytotoxic therapy and antiviral therapies. A comprehensive understanding of the intricacies of the HIV-KSHV coinfection will probably lead to additional advances in therapy and managements for these disorders.

The evolving scenario of non-AIDS-defining cancers: challenges and opportunities of care.

BACKGROUND: The impact of highly active antiretroviral therapies (HAART) on the risk of non-AIDS-defining cancers (NADCs) and the role of biological and clinical factors in their pathogenesis are debated issues. The purpose of this review is to examine the epidemiology, etiology, and not-yet-defined pathogenic characteristics of NADCs and discuss topics such as treatment strategies, comorbidity, and multidrug interactions. Four types of NADCs that deserve special attention are examined: anal cancer, Hodgkin lymphoma (HL), hepatocellular carcinoma, and lung cancer. METHODS: The PubMed database and the Cochrane Library were searched by focusing on NADCs and on the association among NADCs, HAART, aging, and/or chronic inflammation. All articles were reviewed to identify those reporting variables of interest. RESULTS: NADC incidence is twofold higher in patients with HIV/AIDS than in the corresponding general population, and this elevated risk persists despite the use of HAART. The mechanisms that HIV may use to promote the development of NADCs are presently unclear; immunological mechanisms, either immunodeficiency and/or immunoactivation, may play a role. CONCLUSION: Recent clinical studies have suggested that equivalent antineoplastic treatment is feasible and outcome can be similar in HIV-infected patients on HAART compared with uninfected patients for the treatment of HL and anal and lung cancers. However, patients with advanced HIV disease and/or aging-related comorbidities are likely to experience worse outcomes and have poorer tolerance of therapy compared with those with less advanced HIV disease.

Immune deficiency/dysregulation -associated lymphoproliferative disorders. Revised classification and management.

Significant advances in the field of lymphoma have resulted in two recent classification proposals, the International Consensus Classification (ICC) and the 5th edition WHO. A few entities are categorized differently in the ICC compared to the WHO. Nowhere is this more apparent than the immunodeficiency lymphoproliferative disorders. The three previous versions of the WHO classification (3rd, 4th and revised 4th editions) and the ICC focused on four clinical settings in which these lesions arise for primary categorization. In contrast the 2023 WHO 5th edition includes pathologic characteristics including morphology and viral status, in addition to clinical setting, as important information for lesion classification. In addition, the 2023 WHO recognizes a broader number of clinical scenarios in which these lesions arise, including not only traditional types of immune deficiency but also immune dysregulation. With this classification it is hoped that new treatment strategies will be developed leading to better patient outcomes.

Consumption of fruit, vegetables, and other food groups and the risk of nasopharyngeal carcinoma.

PURPOSE: The role of dietary habits in the etiology of nasopharyngeal carcinoma (NPC) has been extensively investigated in high-incidence areas, but evidence is scanty in low-incidence populations. This study aimed to investigate the relationship between NPC risk and a wide range of food groups in the Italian population. METHODS: We conducted a hospital-based case-control study in Italy on 198, histologically confirmed, NPC cases of Caucasian ethnicity, aged 18-76 years. Controls were 594 Caucasian cancer-free patients admitted to general hospitals for acute conditions. Odds ratios (ORs) and the corresponding confidence intervals (CIs) were estimated through logistic regression, adjusting for socio-demographic characteristics, tobacco smoking, alcohol drinking, and energy intake. RESULTS: Elevated vegetable consumption was inversely related to NPC risk (OR for highest vs. lower quartile = 0.51; 95 % CI 0.29-0.90). The association was particularly strong for yellow- or red-pigmented vegetables (OR = 0.31; 95 % CI 0.18-0.54), and this effect was stronger among never smokers (OR = 0.18; 95 % CI 0.06-0.55) than among ever smokers (OR = 0.37; 95 % CI 0.19-0.71). Increased NPC risk emerged for elevated eggs consumption (OR = 2.50; 95 % CI 1.44-4.32; p-trend <0.01). No significant associations emerged between NPC risk and consumption of cereals, meat, fish, dairy products, and sweets. CONCLUSIONS: The study findings show that, also in low-risk populations, vegetable consumption is a protective factor against NPC. The stronger effect for yellow- or red-pigmented vegetables is in agreement with the inverse association reported for carotenoids intake.

Alteration of G1/S transition regulators influences recurrences in head and neck squamous carcinomas.

Head-Neck Squamous Cell Carcinoma (HN-SCC) is a clinically challenging disease associated with a high mortality rate. The chemo-radiotherapy treatments that aim to preserve the organ represent the current gold standard therapy for advanced laryngeal disease, reserving surgery only for non-responsive or relapsed cases. Despite these aggressive approaches, local persistent or recurrent disease remains the primary cause of treatment failure but we still do not have known factors and/or markers able to predict the outcome of the disease and in particular the risk of local relapse. Here we address this point on a series of 54 cases of HN-SCC for whom the presence of local relapse was known. Using immunohistochemistry (IHC) analysis to evaluate protein expression and localization in the recurrence free and recurrence positive samples, we studied the expression of key cell cycle regulators including p53, p16, p27, pRB, Cyclin D1, Cyclin D3, and Stathmin. Overall by analyzing seven different cell cycle regulators we can hypothesize that the alteration of G1/S regulation represents a fundamental event in the onset/progression of HN-SCC cancers and that the associate use of Cyclin D1/p16 expression should be considered as a possible biomarker toward the identification of those patients that will probably develop a recurrent disease and thus should benefit of a more aggressive treatment.

Multiplex analysis of blood cytokines as a prognostic tool in HIV related non-Hodgkin lymphoma patients: a potential role of interleukin-7.

BACKGROUND: Recent studies suggest a powerful prognostic value for blood cytokine levels in different diseases. Non-Hodgkin lymphoma (NHL) still represents one of the main causes of death in the HIV setting, with a wide variation in outcome and survival among patients. We measured blood concentrations of 11 cytokines from HIV-NHL patients at diagnosis and correlated these with the patient outcome to evaluate the prognostic value. METHODS: Luminex technology was used to simultaneously measure serum levels of interleukin IL-2/5/6/7/8/10/13/15, INF-γ, TNF-α and VEGF. Eighty-one consecutive HIV-NHL patients, at diagnosis, were studied. Hazard Ratios (HRs) and corresponding 95% confidence intervals (CIs) of disease-free survival (DFS) and overall survival (OS) were computed according to cytokine levels. HRs were also calculated for continuous variation of IL-7. RESULTS: In the multivariate analysis, statistically significant associations to both DFS and OS were found for IL-7 serum levels ≥ 3.2 pg/mL (HR=5.55, 95%CI:2.38-12.95; HR=3.53, 95%CI:1.60-7.77, respectively), IL-8 ≥ 18 pg/mL (HR=2.69, 95%CI:1.15-6.30; HR=2.35, 95%CI:1.01-5.51, respectively) and IL-10 ≥ 13 pg/mL (HR=2.82, 95%CI: 1.19-6.71; HR=2.98, 95%CI:1.21-7.30, respectively). When the multivariate analyses were mutually adjusted for INF-γ, IL-7, IL-8, IL-10 and IL-15, serum IL-7 ≥ 3.2 pg/mL emerged as factor independently associated to increased risk of DFS (HR=3.63, 95%CI:1.47-8.93) and OS (HR=3.97, 95%CI:1.49-10.57). CONCLUSIONS: IL-7, measured at NHL diagnosis, was the only cytokine strongly and independently associated to both DFS and OS. The multiplex analysis of different blood cytokines' concentration might be useful in defining additive predictive markers in HIV-NHL management and ascertainment of their outcome.

Tissue and circulating PD-L2: moving from health and immune-mediated diseases to head and neck oncology.

Amongst the chief targets of immune-checkpoint inhibitors (ICIs), namely the Programmed cell death protein 1 (PD-1)/PD-Ligands (Ls) axis, most research has focused on PD-L1, while to date PD-L2 is still under-investigated. However, emerging data support PD-L2 relevant expression in malignancies of the head and neck area, mostly in head and neck squamous cell carcinoma (HNSCC) and salivary gland cancers (SGCs). In this context, ICIs have achieved highly heterogeneous outcomes, emphasizing an urgent need for the identification of predictive biomarkers. With the present review, we aimed at describing PD-L2 biological significance by focusing on its tissue expression, its binding to PD-1 and RGMb receptors, and its impact on physiological and anti-cancer immune response. Specifically, we reported PD-L2 expression rates and significant clinical correlates among different head and neck cancer histotypes. Finally, we described the biology of soluble PD-L2 form and its potential application as a prognostic and/or predictive circulating biomarker.

An Inflammatory Signature to Predict the Clinical Benefit of First-Line Cetuximab Plus Platinum-Based Chemotherapy in Recurrent/Metastatic Head and Neck Cancer.

Epidermal growth factor receptor (EGFR) pathway has been shown to play a crucial role in several inflammatory conditions and host immune-inflammation status is related to tumor prognosis. This study aims to evaluate the prognostic significance of a four-gene inflammatory signature in recurrent/metastatic (R/M) head and neck squamous cell carcinoma (HNSCC) patients treated with the EGFR inhibitor cetuximab plus chemotherapy. The inflammatory signature was assessed on 123 R/M HNSCC patients, enrolled in the multicenter trial B490 receiving first-line cetuximab plus platinum-based chemotherapy. The primary endpoint of the study was progression free survival (PFS), while secondary endpoints were overall survival (OS) and objective response rate (ORR). The patient population was subdivided into 3 groups according to the signature score groups. The four-genes-signature proved a significant prognostic value, resulting in a median PFS of 9.2 months in patients with high vs. 6.2 months for intermediate vs. 3.9 months for low values (p = 0.0016). The same findings were confirmed for OS, with median time of 18.4, 13.4, and 7.5 months for high, intermediate, and low values of the score, respectively (p = 0.0001). When ORR was considered, the signature was significantly higher in responders than in non-responders (p = 0.0092), reaching an area under the curve (AUC) of 0.65 (95% CI: 0.55-0.75). Our findings highlight the role of inflammation in the response to cetuximab and chemotherapy in R/M-HNSCC and may have translational implications for improving treatment selection.

LINE-1 hypomethylation is associated with poor outcomes in locoregionally advanced oropharyngeal cancer.

BACKGROUND AND PURPOSE: Currently, human papillomavirus (HPV) positivity represents a strong prognostic factor for both reduced risk of relapse and improved survival in patients with oropharyngeal squamous cell carcinoma (OPSCC). However, a subset of HPV-positive OPSCC patients still experience poor outcomes. Furthermore, HPV-negative OPSCC patients, who have an even higher risk of relapse, are still lacking suitable prognostic biomarkers for clinical outcome. Here, we evaluated the prognostic value of LINE-1 methylation level in OPSCC patients and further addressed the relationship between LINE-1 methylation status and p53 protein expression as well as genome-wide/gene-specific DNA methylation. RESULTS: In this study, DNA was extracted from 163 formalin-fixed paraffin-embedded tissue samples retrospectively collected from stage III-IVB OPSCC patients managed with curative intent with up-front treatment. Quantitative methylation-specific PCR revealed that LINE-1 hypomethylation was directly associated with poor prognosis (5-year overall survival-OS: 28.1% for LINE-1 methylation < 35% vs. 69.1% for ≥ 55%; p < 0.0001). When LINE-1 methylation was dichotomized as < 55% versus ≥ 55%, interaction with HPV16 emerged: compared with hypermethylated HPV16-positive patients, subjects with hypomethylated HPV16-negative OPSCC reported an adjusted higher risk of death (HR 4.83, 95% CI 2.24-10.38) and progression (HR 4.54, 95% CI 2.18-9.48). Tumor protein p53 (TP53) gene is often mutated and overexpressed in HPV-negative OPSCC. Since p53 has been reported to repress LINE-1 promoter, we then analyzed the association between p53 protein expression and LINE-1 methylation levels. Following p53 immunohistochemistry, results indicated that among HPV16-negative patients with p53 ≥ 50%, LINE-1 methylation levels declined and remained stable at approximately 43%; any HPV16-positive patient reported p53 ≥ 50%. Finally, DNA methylation analysis demonstrated that genome-wide average methylation level at cytosine-phosphate-guanine sites was significantly lower in HPV16-negative OPSCC patients who relapsed within two years. The subsequent integrative analysis of gene expression and DNA methylation identified 20 up-regulated/hypomethylated genes in relapsed patients, and most of them contained LINE-1 elements in their promoter sequences. CONCLUSIONS: Evaluation of the methylation level of LINE-1 may help in identifying the subset of OPSCC patients with bad prognosis regardless of their HPV status. Aberrant LINE-1 hypomethylation might occur along with TP53 mutations and lead to altered gene expression in OPSCC.

Multicentre study on resection margins in carcinoma of the oral cavity, oro-hypopharynx and larynx.

Objective: The prognostic significance of the resection margins is still subject of conflicting opinions. The purpose of this paper is to report the results of a study on the margins in carcinoma of the oral cavity, oro-hypopharynx and larynx. Methods: A multicentre prospective study was carried out between 2015 and 2018 with the participation of 10 Italian reference hospitals. The primary objective was to evaluate local control in patients with well-defined clinical characteristics and comprehensive histopathological information. Results: During the study period, 455 patients were enrolled; the minimum follow-up was 2 years. Previous treatment, grading and fresh specimen examination were identified as risk factors for local control in multivariate analysis. On the basis of these results, it seems possible to delineate "risk profiles" for different oncological outcomes. Discussion: The prognostic significance of the margins is reduced, and other risk factors emerge, which require diversified treatment and follow-up. Conclusions: Multidisciplinary treatment with adjuvant therapy, if indicated, reduces the prognostic importance of margins. Collaboration with a pathologist is an additional favourable prognostic factor and quality indicator.An appendix with literature review is present in the online version.

High-dose therapy and autologous peripheral blood stem cell transplantation as salvage treatment for AIDS-related lymphoma: long-term results of the Italian Cooperative Group on AIDS and Tumors (GICAT) study with analysis of prognostic factors.

After the introduction of highly active antiretroviral therapy (HAART), intensive treatment, including high-dose therapy (HDT) and peripheral blood stem cell transplantation (PBSCT), has become feasible in HIV-positive patients with Hodgkin (HL) and non-Hodgkin (NHL) lymphoma. Herein, we report the long-term results, on an intention-to-treat basis, of a prospective study on HDT and PBSCT in 50 HIV-positive HAART-responding patients with refractory/relapsed lymphoma. After debulking therapy, 2 patients had early toxic deaths, 10 had chemoresistant disease, 6 failed stem cell mobilization, 1 refused collection, and 4 progressed soon after PBSC harvest. Twenty-seven actually received transplant. Twenty-one patients are alive and disease-free after a median follow-up of 44 months (OS, 74.6%; PFS, 75.9%). Only lymphoma response significantly affected OS after transplantation. In multivariate analyses both lymphoma stage and low CD4 count negatively influenced the possibility to receive transplant. Median OS of all 50 eligible patients was 33 months (OS, 49.8%; PFS, 48.9%). Low CD4 count, marrow involvement, and poor performance status independently affected survival. PBSCT is a highly effective salvage treatment for chemosensitive AIDS-related lymphoma. It seems rational to explore its use earlier during the course of lymphoma to increase the proportion of patients who can actually receive transplant.

Immunodeficiency-associated Hodgkin lymphoma.

Introduction: Hodgkin lymphoma (HL) can occur in different host conditions, i.e. in the general population and immunocompromised individuals, either during HIV infection or solid organ/hematopoietic transplantation and immunosuppressive drug treatment.Areas covered: Areas covered include multidimensional characteristics of tumor cells and cellular composition of tumor microenvironment of HL. Current conventional treatments and new treatment strategies for HL in immunosuppressed patients, especially in persons living with HIV (PLWH), are also discussed.PubMed and MEDLINE were used for database searches to identify articles in English published from 1989 to 2020.Expert opinion: For people with post-transplant HL or for those with HIV/AIDS-associated HL, standard treatments mirror those in the general population. In the last decade, the combination of cART with anti-neoplastic treatments, alongside with current anti-rejection therapies, has increased long-term survival of people with HL and acquired immune deficiencies. High-dose chemotherapy and autologous stem cell transplantation have been favorably proven as salvage therapy in PLWH with relapsed and refractory HL. Immune checkpoint inhibitors emerged as an area of clinical investigation for relapsed and refractory HL in the general population. Pembrolizumab, an anti-programmed cell death protein 1 (PD-1) drug, resulted safe in PLWH indicating that PD-1 ligand assessment should be advisable in HIV-associated HL.

A pre-operative prognostic score for the selection of patients for salvage surgery after recurrent head and neck squamous cell carcinomas.

Salvage surgery in recurrent head and neck squamous cell carcinoma has a poor outcome, both in terms of survival and quality of life. Therefore, the identification of pre-operative prognostic factors to improve the selection of patients who could benefit the most from salvage surgery is clinically relevant. The present study is a single-center retrospective analysis of 164 patients treated with salvage surgery after recurrence of head and neck cancer. Progression free survival and overall survival were calculated through Kaplan-Meier method. Hazard risk (HR) and corresponding confidence intervals (CI) were estimated through Cox proportional hazard model, adjusting for potential confounders. Significant predictors were combined into a prognostic score, attributing one point to each factor. Progression-free survival and overall survival were respectively 50.3% and 56.5% at 2 years, and 36.6% and 44.2% at 5 years. Four pre-operative factors were independently associated with poor prognosis: age > 70 years (HR = 2.18; 95% CI 1.27-3.73), initial stage IV (HR = 2.37; 95% CI 1.18-4.76), disease free interval < 12 months (HR = 1.72; 95% CI 1.01-2.94), and loco-regional recurrence (HR = 2.22; 95% CI 1.22-4.04). No post operative factor was associated with oncologic outcomes. Patients with 3-4 unfavorable factors showed a 5-year overall survival of 0.0% compared to 65.7% in those with 0-1 unfavorable factors (HR = 5.61; 95% CI 2.89-10.92). Despite the low number of patients, 3-4 unfavorable factors were associated to worse prognosis in all sub-sites. In conclusion, age > 70 years, initial stage IV, disease-free interval < 12 months, and loco-regional recurrence are strong independent pre-operative predictors of poor outcome in patients undergoing salvage surgery. Patients with two or more of these factors should be informed about the low success rate after salvage surgery and alternative treatments should be considered.

Cetuximab in locally advanced head and neck squamous cell carcinoma: Biological mechanisms involved in efficacy, toxicity and resistance.

Since its introduction, the use of cetuximab in the treatment of head and neck squamous cell carcinoma (HNSCC) has experienced an evolution. Currently, cetuximab associated with radiotherapy is limited to the treatment of patients affected by a locally advanced malignancy and unfit for cisplatin. However, reliable biomarkers of cetuximab efficacy in this cancer setting are still lacking. This review focuses on the mechanisms of action of cetuximab, highlighting, in particular, the consequences of the binding to EGFR, and the pathways involved in the development of adverse events or acquired resistance. Indeed, adverse events, such as skin rash, have been associated with cetuximab efficacy in HNSCC several times. Acquired resistance is associated with microenvironment plasticity, which is, in turn, characterized by an increased immune infiltrate. The better definition of patients eligible for this kind of therapy could improve HNSCC management, possibly proposing a combined treatment with radiotherapy, cetuximab and immune checkpoint inhibitors as recently investigated.