Evasion of apoptosis and treatment resistance in squamous cell carcinoma of the head and neck.

Combinations of surgery, radiotherapy and chemotherapy can eradicate tumors in patients with locally advanced squamous cell carcinoma of the head and neck (LA SCCHN), but a significant proportion of tumors progress, recur, or do not respond to therapy due to treatment resistance. The prognosis for these patients is poor, thus new approaches are needed to improve outcomes. Key resistance mechanisms to chemoradiotherapy (CRT) in patients with LA SCCHN are alterations to the pathways that mediate apoptosis, a form of programmed cell death. Targeting dysregulation of apoptotic pathways represents a rational therapeutic strategy in many types of cancer, with a number of proteins, including the pro-survival B-cell lymphoma 2 family and inhibitors of apoptosis proteins (IAPs), having been identified as druggable targets. This review discusses the mechanisms by which apoptosis occurs under physiological conditions, and how this process is abnormally restrained in LA SCCHN tumor cells, with treatment strategies aimed at re-enabling apoptosis in LA SCCHN also considered. In particular, the development of, and future opportunities for, IAP inhibitors in LA SCCHN are discussed, in light of recent encouraging proof-of-concept clinical trial data.

Managing cisplatin-ineligible patients with resected, high-risk, locally advanced squamous cell carcinoma of the head and neck: Is there a standard of care?

For the past 2 decades, cisplatin-based adjuvant chemoradiotherapy (CRT) has remained the standard of care for patients with resected, locally advanced squamous cell carcinoma of the head and neck (LA SCCHN) who are at high risk of disease recurrence. However, many patients are deemed ineligible for cisplatin-based CRT because of poor performance status, advanced biological age, poor renal function, or hearing loss. Because outcomes with radiotherapy (RT) alone remain poor, patients at high risk of disease recurrence deemed ineligible to receive cisplatin are a population with a significant unmet medical need, and alternative systemic therapy options in combination with RT are urgently needed. Clinical guidelines and consensus documents have provided definitions for cisplatin ineligibility; however, areas of debate include thresholds for age and renal impairment and criteria for hearing loss. Furthermore, the proportion of patients with resected LA SCCHN who are cisplatin ineligible remains unclear. Because of a scarcity of clinical studies, treatment selection for patients with resected, high-risk LA SCCHN who are deemed ineligible to receive cisplatin is often based on clinical judgment, with few treatment options specified in international guidelines. In this review, we discuss considerations related to cisplatin ineligibility in patients with LA SCCHN, summarize the limited clinical evidence for adjuvant treatment of patients with resected high-risk disease, and highlight ongoing clinical trials that have the potential to provide new treatment options in this setting.

First-line cetuximab + platinum-based therapy for recurrent/metastatic head and neck squamous cell carcinoma: A real-world observational study-ENCORE.

BACKGROUND: ENCORE, an observational, prospective, open-label study, investigated real-world treatment practices and outcomes with cetuximab plus platinum-based therapy (PBT) in first-line (1L) recurrent and/or metastatic squamous cell carcinoma of the head and neck (R/M SCCHN). AIMS: This multinational study aimed to investigate the long-term use of cetuximab plus PBT for 1L R/M SCCHN in a clinical setting. In particular, this study aimed to explore clinical considerations such as the decision to prescribe cetuximab plus PBT in R/M SCCHN, the mode and duration of treatment, and patient outcomes. METHODS AND RESULTS: Previously untreated patients with R/M SCCHN whose planned treatment was cetuximab plus PBT were enrolled from 6 countries. Among 221 evaluable patients, planned treatments included cetuximab plus carboplatin (31.2%), cisplatin plus 5-fluorouracil (31.7%), or carboplatin plus 5-fluorouracil (23.1%); 3.2% included a taxane, and 45.2% did not include 5-fluorouracil. Cetuximab treatment was planned for a fixed duration (≤24 weeks) in 15 patients (6.8%) and until disease progression in 206 (93.2%). Median progression-free survival and overall survival were 6.5 and 10.8 months, respectively. Grade ≥3 adverse events occurred in 39.8% of patients. Serious adverse events occurred in 25.8% of patients; 5.4% were cetuximab-related. CONCLUSION: In patients with R/M SCCHN, first-line cetuximab plus PBT was feasible and modifiable in a real-world setting with similar toxicity and efficacy as in the pivotal phase III EXTREME trial. CLINICAL TRIAL REGISTRATION NUMBER: EMR 062202-566.

Inhibiting the inhibitors: Development of the IAP inhibitor xevinapant for the treatment of locally advanced squamous cell carcinoma of the head and neck.

Standard of care for patients with locally advanced squamous cell carcinoma of the head and neck (LA SCCHN) is surgery followed by chemoradiotherapy (CRT) or definitive CRT. However, approximately 50 % of patients with LA SCCHN develop disease recurrence or metastasis within 2 years of completing treatment, and the outcome for these patients is poor. Despite this, the current treatment landscape for LA SCCHN has remained relatively unchanged for more than 2 decades, and novel treatment options are urgently required. One of the key causes of disease recurrence is treatment resistance, which commonly occurs due to cancer cells' ability to evade apoptosis. Evasion of apoptosis has been in part attributed to the overexpression of inhibitor of apoptosis proteins (IAPs). IAPs, including X-linked IAP (XIAP) and cellular IAP 1 and 2 (cIAP1/2), are a class of proteins that regulate apoptosis induced by intrinsic and extrinsic apoptotic pathways. IAPs have been shown to be overexpressed in SCCHN, are associated with poor clinical outcomes, and are, therefore, a rational therapeutic target. To date, several IAP inhibitors have been investigated; however, only xevinapant, a potent, oral, small-molecule IAP inhibitor, has shown clinical proof of concept when combined with CRT. Specifically, xevinapant demonstrated superior efficacy in combination with CRT vs placebo + CRT in a randomized, double-blind, phase 2 trial in patients with unresected LA SCCHN. Here, we describe the current treatment landscape in LA SCCHN and provide the rationale for targeting IAPs and the clinical data reported for xevinapant.

Avelumab and cetuximab as a therapeutic combination: An overview of scientific rationale and current clinical trials in cancer.

Treatment outcomes have improved with the advent of immune checkpoint inhibitors and small molecule inhibitors. However, many patients do not respond with single agents. Consequently, ongoing research is focused on the use of combination therapies to increase clinical efficacy by potential synergistic effects. Here, we outline ongoing trials and review the rationale and evidence for the combination of avelumab, an anti-programmed death ligand 1 (PD-L1) immunoglobulin G1 (IgG1) monoclonal antibody (mAb), with cetuximab, an anti-epidermal growth factor receptor (EGFR) IgG1 mAb. Avelumab is approved as a monotherapy for the treatment of Merkel cell carcinoma and urothelial carcinoma, and in combination with axitinib for renal cell carcinoma; cetuximab is approved in combination with chemotherapy for the treatment of squamous cell carcinoma of the head and neck (SCCHN) and RAS wild-type metastatic colorectal cancer, and in combination with radiation therapy for SCCHN. Avelumab binds to PD-L1 expressed on tumor cells and immune regulatory cells, thus blocking its interaction with programmed death 1 and reventing T-cell suppression; cetuximab inhibits the EGFR signaling pathway, inhibiting proliferation and inducing apoptosis. Both therapies have complementary mechanisms of action and may also activate the immune system to induce innate effector function through the binding of their Fc regions to natural killer (NK) cells. Furthermore, cetuximab combined with chemotherapy has been shown to induce immunogenic cell death and leads to an increase in tumor-infiltrating CD8+ T and NK cells, which should synergize with the immunostimulatory effects of avelumab. Prospective studies will investigate this combination and inform future treatment strategies.

Treating Patients With Locally Advanced Squamous Cell Carcinoma of the Head and Neck Unsuitable to Receive Cisplatin-Based Therapy.

Concurrent chemoradiotherapy with high-dose cisplatin (100 mg/m2 every 3 weeks) is the preferred regimen with curative intent for patients with unresected locally advanced squamous cell carcinoma of the head and neck (LA SCCHN). This treatment is associated with acute and late toxicities, including myelosuppression, severe nausea/vomiting, irreversible renal failure, hearing loss, and neurotoxicity. Because of cisplatin's safety profile, treatment adherence to high-dose cisplatin can be suboptimal. Patients commonly receive less than the total cumulative target dose of 300 mg/m2 or the minimum recommended dose of 200 mg/m2, which can have a negative impact on locoregional control and survival. Alternatively, cetuximab plus radiotherapy may be most suitable for patients at high risk of non-adherence to high-dose cisplatin. We discuss the baseline characteristics dictating the unsuitability/borderline unsuitability of cisplatin and the available alternative evidence-based treatment regimens for patients with LA SCCHN. We non-systematically reviewed published phase II and III trials and retrospective analyses of high-dose cisplatin-based chemoradiation in LA SCCHN conducted between 1987 and 2018, focusing on recent key phase III studies. We defined the baseline characteristics and associated prescreening tests to determine unsuitability and borderline unsuitability for high-dose cisplatin in combination with radiotherapy in patients with LA SCCHN. Patients with any pre-existing comorbidities that may be exacerbated by high-dose cisplatin treatment can be redirected to a non-cisplatin-based option to minimize the risk of treatment non-adherence. High-dose cisplatin plus radiotherapy remains the preferred treatment for fit patients with unresected LA SCCHN; patients who are unsuitable or borderline unsuitable for high-dose cisplatin could be identified using available tests for potential comorbidities and should be offered alternative treatments, such as cetuximab plus radiotherapy.