Immunotherapy for head and neck squamous cell carcinoma: current status and perspectives

Immune checkpoint inhibitors (ICIs) have revolutionized the treatment of several solid cancers, including head and neck squamous cell carcinoma (HNSCC). First approved for second-line settings, ICIs are now used for the first-line treatment of HNSCCs, mainly in combination with standard chemotherapy. This review focuses on the results of the main phase III studies evaluating ICIs in recurrent or metastatic HNSCCs. The efficacy and indications according to the PD-L1 status, the main predictive biomarker, are discussed. The results of trials assessing ICI efficacy for locally advanced disease, including the neoadjuvant setting are also discussed. Finally, therapeutic combinations that are potential treatments for HNSCCs, including ICIs and targeted therapies such as anti-EGFR agents, are presented.

Immunologically active phenotype by gene expression profiling is associated with clinical benefit from PD-1/PD-L1 inhibitors in real-world head and neck and lung cancer patients

INTRODUCTION

Identification of tumours harbouring an overall active immune phenotype may help for selecting patients with advanced head and neck squamous cell carcinomas (HNSCC) and non-small cell lung cancer (NSCLC) who may benefit from immunotherapies. Our objective was to develop a reliable and stable scoring system to identify those immunologically active tumours.

METHODS

Using gene expression profiles of 421 HNSCC, we developed a score to identify immunologically active tumours. Validation of the 'HOT' score was done in 40 HNSCC and 992 NSCLC. Stability of the 'HOT' score was tested in paired HNSCC samples from diagnostic biopsies versus surgically resected specimens, untreated versus recurrent samples, and pre-versus post-cetuximab samples in a total of 76 patients. The association between the 'HOT' score with overall survival (OS) and progression-free survival (PFS) was tested in 184 patients with HNSCC or NSCLC treated with PD-1/PD-L1 inhibitors.

RESULTS

A 27-gene expression based 'HOT' score was correlated with: (i) PD-L1 and IDO1 expression, (ii) TCD8 infiltrate and (iii) activation of the IFN-γ pathway. The HOT score concordance when comparing diagnostic biopsies and surgically resected specimens was higher than in untreated samples versus recurrent or pre-versus post-cetuximab samples. In 102 and 82 patients with HNSCC or NSCLC treated with PD-1/PD-L1 inhibitors, the HOT score was associated with an improved OS and PFS in multivariate analysis.

CONCLUSION

The 'HOT' score is a simple and robust approach to identify real-world patients with HNSCC and NSCLC immunologically active tumours who may benefit from PD-1/PD-L1 inhibitors.

Immunotherapy for head and neck cancer: present and future

Immunotherapy has changed the treatment landscape of Head and Neck cancer (HNC). Different immune checkpoint inhibitors targeting PD-1/PD-L1 axis have been approved for different disease settings and many others, alone or in combination, are currently under investigation. Otherwise, as in other cancer types, efficacy, and resistance mechanisms, are not clearly understood. Considering the heterogeneity of the benefit reported in clinical trials, cost-efficacy analysis and the development of an effective patient selection are encouraged. Different pathways involving innate immunity, regulatory T lymphocytes and microbiome are emerging as new potential biomarkers, supported by preclinical and translational data. In this review we report current evidence on immunotherapy in HNC with updates from the main 2021 oncology events as ASCO, AACR and ESMO meetings. We focus on clinical trials results of single agent and combination immunotherapy in different clinical scenario, from (neo)adjuvant to metastatic setting, describing also novel evidence about efficacy and resistance biomarkers.

Phase II Clinical Trial of Neoadjuvant and Adjuvant Pembrolizumab in Resectable Local-Regionally Advanced Head and Neck Squamous Cell Carcinoma

PURPOSE

Patients with resected, local-regionally advanced, head and neck squamous cell carcinoma (HNSCC) have a one-year disease-free survival (DFS) rate of 65%-69% despite adjuvant (chemo)radiotherapy. Neoadjuvant PD-1 immune-checkpoint blockade (ICB) has demonstrated clinical activity, but biomarkers of response and effect on survival remain unclear.

PATIENTS AND METHODS

Eligible patients had resectable squamous cell carcinoma of the oral cavity, larynx, hypopharynx, or oropharynx (p16-negative) and clinical stage T3-T4 and/or two or more nodal metastases or clinical extracapsular nodal extension (ENE). Patients received neoadjuvant pembrolizumab 200 mg 1-3 weeks prior to surgery, were stratified by absence (intermediate-risk) or presence (high-risk) of positive margins and/or ENE, and received adjuvant radiotherapy (60-66 Gy) and concurrent pembrolizumab (every 3 weeks × 6 doses). Patients with high-risk HNSCC also received weekly, concurrent cisplatin (40 mg/m2). Primary outcome was one-year DFS. Secondary endpoints were one-year overall survival (OS) and pathologic response (PR). Safety was evaluated with CTCAE v5.0.

RESULTS

From February 2016 to October 2020, 92 patients enrolled. The median age was 59 years (range, 27-80), 30% were female, 86% had stage T3-T4, and 69% had ≥N2. At a median follow-up of 28 months, one-year DFS was 97% (95% CI, 71%-90%) in the intermediate-risk group and 66% (95% CI, 55%-84%) in the high-risk group. Patients with a PR had significantly improved one-year DFS relative to patients without response (93% vs. 72%, hazard ratio 0.29; 95% CI, 11%-77%). No new safety signals were identified.

CONCLUSIONS

Neoadjuvant and adjuvant pembrolizumab increased one-year DFS rate in intermediate-risk, but not high-risk, HNSCC relative to historical control. PR to neoadjuvant ICB is a promising surrogate for DFS.

Neoadjuvant PD-1/PD-L1 Inhibitors for Resectable Head and Neck Cancer: A Systematic Review and Meta-analysis

Importance

The emerging approach of neoadjuvant immunotherapy for solid cancers has set the ground for the integration of programmed cell death 1 (PD-1)/PD-1 ligand 1 (PD-L1) inhibitors into the neoadjuvant setting of head and neck squamous cell carcinoma (HNSCC) treatment.

Objective

To assess the reported efficacy and safety of neoadjuvant immunotherapy for resectable HNSCC.

Data Sources and Study Selection

Electronic databases, including PubMed (MEDLINE), Embase, the Cochrane Library, and ClinicalTrials.gov were systematically searched for published and ongoing cohort studies and randomized clinical trials that evaluate neoadjuvant immunotherapy for resectable HNSCC. The search results generated studies from 2015 to July 2021.

Data Extraction and Synthesis

Two investigators (R.M. and L.K.) independently identified and extracted articles for potential inclusion. Random and fixed models were used to achieve pooled odds ratios. All results are presented with 95% CIs. Data quality was assessed by means of the Cochrane Collaboration's risk of bias tool.

Main Outcomes and Measures

The primary outcomes were reported efficacy, evaluated by major pathological response and pathological complete response in the primary tumors and lymph nodes separately, and safety, assessed by preoperative grade 3 to 4 treatment-related adverse events and surgical delay rate.

Results

A total of 344 patients from 10 studies were included. In 8 studies, neoadjuvant immunotherapy only was administered, and the other 2 studies combined immunotherapy with neoadjuvant chemotherapy and/or radiotherapy. The overall major pathological response rate in the primary tumor sites from studies reporting on neoadjuvant immunotherapy only was 9.7% (95% CI, 3.1%-18.9%) and the pathological complete response rate was 2.9% (95% CI, 0%-9.5%). Preoperative grade 3 to 4 treatment-related adverse events were reported at a rate of 8.4% (95% CI, 0.2%-23.2%) and surgical delay at a rate of 0% (95% CI, 0%-0.9%). There was a favorable association of neoadjuvant immunotherapy with all outcome measures. The subgroup analyses did not find one specific anti-PD-1/PD-L1 agent to be superior to another, and the favorable association was demonstrated by either immunotherapy alone or in combination with anti-CTLA-4.

Conclusions and Relevance

In this systematic review and meta-analysis, neoadjuvant anti-PD-1/PD-L1 immunotherapy for resectable HNSCC was well tolerated and may confer therapeutic advantages implied by histopathological response. Long-term outcomes are awaited.

Multifocal regression and pathologic response predicts recurrence after neoadjuvant chemotherapy in head and neck squamous cell carcinoma

OBJECTIVES

Complete pathological response after neoadjuvant chemotherapy (NAC) in head and neck squamous cell carcinomas (HNSCC) is a good prognostic factor. Multifocal regression post-NAC in breast cancer has proven to impact locoregional control (LRC) but has not been evaluated in HNSCC. We evaluate the impact of multifocal regression and major pathologic response (MPR) on survival indices in HNSCC.

MATERIALS AND METHODS

Retrospective review of HNSCC patients receiving NAC followed by surgery with curative intent between March 2016 to March 2019 at MD Anderson Cancer Center. Tumor focality (uni- or multifocal), pathologic response and other pathologic data were collected. MPR was defined as ≤ 10% residual tumor. Overall survival (OS) and LRC were analyzed and multivariate Cox regression analysis was performed.

RESULTS

101 patients were analyzed, with 18.8% pathologic complete response, 18.8% with 1-10% viable tumor and 60.4% with > 10% viable tumor. 61 (60.4%) had unifocal disease while 19 (18.8%) had multifocal disease. Tumor focality was significantly associated with LRC but not OS, where the 3-year LRC was 82%, 69% and 52% (p = 0.015) for no viable tumor, unifocal disease and multifocal disease respectively. On multivariate analysis, multifocal disease (HR 10.43; 95 %CI 1.24-87.5) and extranodal extension (HR 4.4; 95 %CI 1.60-12.07) continued to be significant independent predictors of LRC. MPR group displayed significantly better 3-year OS (75% vs 51%, p = 0.041) and 3-year LRC (80% vs 62%, p = 0.011) than those with > 10% viable tumor.

CONCLUSION

Multifocal regression and less than MPR after NAC in HNSCC predicts for locoregional recurrence and should be routinely reported.

[Medicinal tumor treatment of oropharyngeal cancer]

BACKGROUND

The number of patients suffering from human papillomavirus (HPV)-associated oropharyngeal cancer has increased in recent decades. To date, the role of medical therapy in patients with squamous cell carcinoma of the head and neck region has only been established in the refractory or metastatic setting (r/m HNSCC).

OBJECTIVE

What are the current treatment options for patients with r/m HNSCC or r/m oropharyngeal cancer?

MATERIALS AND METHODS

A literature search was conducted on systemic treatment of oropharyngeal cancer and r/m HNSCC.

RESULTS

There is currently no standard treatment for patients with oropharyngeal cancer in refractory or metastatic stages. Since 2017, immunotherapy with checkpoint inhibitors has become increasingly important in the treatment of r/m HNSCC patients. First-line therapy was recently adapted based on the results of the KEYNOTE-48 (KN048) study. For selected patients with r/m HNSCC, there now exists a chemotherapy-free treatment option. Use of immunotherapy also in earlier stages of HNSCC can be expected in the near future.

CONCLUSION

Medical therapy of r/m HNSCC patients is in a period of great change. Treatment is increasingly based on combination therapy with checkpoint inhibitors.

Optimizing Treatment De-Escalation in Head and Neck Cancer: Current and Future Perspectives

Treatment of locoregionally advanced head and neck squamous cell carcinoma involves a multidisciplinary approach that combines surgery, radiotherapy, and systemic therapy. These curative strategies are associated with significant acute and long-term toxicities. With the emergence of human papillomavirus (HPV) as an etiologic factor associated primarily with oropharyngeal squamous cell carcinoma, higher cure rates juxtaposed with substantial treatment-related morbidity and mortality has led to interest in de-escalated therapeutic strategies, with the goal of optimizing oncologic outcomes while reducing treatment-related toxicity. Currently explored strategies include replacing, reducing, or omitting cytotoxic chemotherapy; reducing dose or volume of radiotherapy; and incorporation of less-invasive surgical approaches. Potential biomarkers to select patients for treatment de-escalation include clinical risk stratification, adjuvant de-escalation based on pathologic features, response to induction therapy, and molecular markers. The optimal patient selection and de-escalation strategy is critically important in the evolving treatment of locoregional head and neck cancer. Recently, two large phase III trials, RTOG 1016 and De-ESCALaTE, failed to de-escalate treatment in HPV-associated head and neck cancer by demonstrating inferior outcomes by replacing cisplatin with cetuximab in combination with radiation. This serves as a cautionary tale in the future design of de-escalation trials in this patient population, which will need to leverage toxicity and efficacy endpoints. Our review summarizes completed and ongoing de-escalation trials in head and neck cancer, with particular emphasis on biomarkers for patient selection and clinical trial design. IMPLICATIONS FOR PRACTICE: The toxicity associated with standard multimodality treatment for head and neck cancer underscores the need to seek less-intensive therapies with a reduced long-term symptom burden through de-escalated treatment paradigms that minimize toxicity while maintaining oncologic control in appropriately selected patients. Controversy regarding the optimal de-escalation strategy and criteria for patient selection for de-escalated therapy has led to multiple parallel strategies undergoing clinical investigation. Well-designed trials that optimize multimodal strategies are needed. Given the absence of positive randomized trials testing de-escalated therapy to date, practicing oncologists should exercise caution and administer established standard-of-care therapy outside the context of a clinical trial.

Novel Strategies to Effectively De-escalate Curative-Intent Therapy for Patients With HPV-Associated Oropharyngeal Cancer: Current and Future Directions

The treatment of patients with HPV-associated oropharyngeal cancer (HPV-OPC) is rapidly evolving and challenging the standard of care of definitive radiotherapy with concurrent cisplatin. There are numerous promising de-escalation strategies under investigation, including deintensified definitive chemoradiotherapy, transoral surgery followed by de-escalated adjuvant therapy, and induction chemotherapy followed by de-escalated locoregional therapy. Definitive radiotherapy alone or with cetuximab is not recommended for curative-intent treatment of patients with locally advanced HPV-OPC. The results of ongoing phase III studies are awaited to help answer key questions and address ongoing controversies to transform the treatment of patients with HPV-OPC. Strategies for de-escalation under investigation include the incorporation of immunotherapy and the use of novel biomarkers for patient selection for de-escalation.

Prevalence of PD-L1 expression in head and neck squamous precancerous lesions: a systematic review and meta-analysis

BACKGROUND

Studies concerning programmed death-ligand 1 (PD-L1) expression in precancerous lesions of head and neck (HN) region have shown variable results.

METHODS

We systematically reviewed the published evidence on PD-L1 expression in HN precancerous lesions.

RESULTS

Of 1058 original articles, 14 were included in systematic review and 9 in meta-analysis. The pooled estimate of PD-L1 expression was 48.25% (confidence interval [CI] 21.07-75.98, I² 98%, tau2 0.18). PD-L1 expression appeared to be more frequent in precancerous lesions than in normal mucosa (risk ratio [RR] 1.65, CI 0.65-4.03, I² 91%, tau2 0.82) and less frequent than in invasive squamous cell carcinoma (RR 0.68, CI 0.43-1.08, I² 91%, tau2 0.22).

CONCLUSIONS

PD-L1 expression could reflect a point of balance between host immune response and cancer escape ability. High heterogeneity and moderate quality suggest that further studies with larger sample size and more rigorous case selection will allow more precise assessment of PD-L1 expression in HN precancerous lesions.

Genomics and precision surgery for head and neck squamous cell carcinoma

The identification of the biological determinants that shape the response of tumors to medical therapies offers perspectives for better patient stratification and therapeutic targeting. Here, we discuss how genomics could help to improve the surgical treatment of head and neck squamous cell carcinoma (HNSCC). We examine the potential use of genomic analyses for: i) refining and standardizing the indications for surgery, ii) the choice of surgical procedure, and iii) the follow-up of patients with resected tumors. We highlight the studies that used genomics to explore the contribution of tumor biology to the outcome of surgery. We discuss the important developments that are challenging current surgical practice in HNSCC, such as neoadjuvant immunotherapy and the analysis of circulating DNA. Genomic analyses provide practical tools that could help improve the pathological diagnosis and staging of HNSCC, and increase the appreciation of the importance of tumor biology in the outcome of surgery. Identification of biomarkers will likely contribute to a move toward precision surgery of HNSCC, i.e. the personalization of surgical practice based on tumor biology.

The neoadjuvant paradigm reinvigorated: a review of pre-surgical immunotherapy in HNSCC

Background

There remains up to a 50% recurrence rate in advanced p16- head and neck squamous cell carcinoma with current standard of care treatment. In an attempt to improve survival, multiple trials administering induction or neoadjuvant chemotherapy have been conducted but none demonstrated improved overall survival. The established efficacy of immune checkpoint inhibitors in the recurrent and metastatic setting has produced widespread interest in their neoadjuvant use.

Purpose

To survey the landscape of active neoadjuvant immunotherapy trials in head and neck squamous cell carcinoma and summarize and synthesize currently available outcomes from these trials.

Conclusions

Neoadjuvant immunotherapy has proven safe and well tolerated in head and neck squamous cell carcinoma with encouraging efficacy results, including relatively high rates of pathologic response. Ongoing studies offer an opportunity to study immune responses in vivo. PD-L1 positivity, high tumor mutational burden and infiltration of NK cells, CD8, CD26 and Tim3 positive lymphocytes at time of surgery have been correlated with pathologic responses. We await updated reports of disease free survival and overall survival data and results of ongoing phase III studies utilizing neoadjuvant immunotherapy to determine if this treatment paradigm will have a place in the standard of care treatment in head and neck squamous cell carcinoma.

Immunotherapy for head and neck cancer: Recent advances and future directions

Three randomized phase III trials have now conclusively proven that exposure to a PD-1 inhibitor prolongs survival in recurrent/metastatic (R/M) HNSCC, and it is clear that such agents should be used in the management of all patients who do not have contraindications to their use. Two of these phase III randomized trials showed that the anti-PD1 antibodies nivolumab and pembrolizumab were superior to investigators' choice chemotherapy in second-line platinum-refractory R/M HNSCC. Recently, a third phase III randomized trial, KEYNOTE-048, showed that pembrolizumab with chemotherapy was superior to the EXTREME regimen (cis- or carboplatin, 5-fluorouracil (5-FU) and cetuximab) in all patients, and pembrolizumab monotherapy was superior in patients whose tumors express PD-L1 in first-line R/M HNSCC. Pembrolizumab is now approved as monotherapy in PD-L1 expressing disease (combined positive score ≥1) or in combination with chemotherapy for all patients with R/M HNSCC. Thus, PD-L1 biomarker testing will be routinely used in R/M HNSCC, and this employs a scoring system that incorporates immune cell staining, referred to as the combined positive score (CPS). Additionally, for the 85% of patients with PD-L1 CPS ≥1, clinical judgment will guide the choice of pembrolizumab monotherapy or pembrolizumab plus chemotherapy, until more detailed clinical data are forthcoming to better inform this decision. In this article we discuss the clinical trials leading to these therapeutic advances and we will review initial results from clinical trials in previously untreated, locally advanced disease, and those using novel combinations of checkpoint inhibitors, co-stimulatory agonists, and therapeutic vaccines.