Neoadjuvant immunoradiotherapy results in high rate of complete pathological response and clinical to pathological downstaging in locally advanced head and neck squamous cell carcinoma

The Downstaging Concept in Treatment-Resistant Depression: Spotlight on Ketamine

Treatment-resistant depression is a pleomorphic phenomenon occurring in 30% of patients with depression. The chance to achieve remission decreases with every subsequent episode. It constitutes a significant part of the global disease burden, causes increased morbidity and mortality, and is associated with poor quality of life. It involves multiple difficult-to-treat episodes, with increasing resistance over time. The concept of staging captures the process of changes causing increasing treatment resistance and global worsening of functioning in all areas of life. Ketamine is a novel rapid-acting antidepressant with neuroplastic potential. Here, we argue that ketamine use as an add-on treatment of resistant major depressive disorder, based on its unique pharmacological properties, can reverse this process, give hope to patients, and prevent therapeutic nihilism.

Amplifying Dendritic Cell Activation by Bioinspired Nanometal Organic Frameworks for Synergistic Sonoimmunotherapy

Despite recent advancements of sonodynamic therapy (SDT) in cancer immunotherapy, challenges have yet to be surmounted to further boost its immunotherapeutic efficacy due to the low-level tumor antigens presentation of dendritic cells (DCs). Cell membrane camouflaged-nanoparticles can integrate the neoantigens of the cancer cell membrane with the multifunctionalities of synthetic nanocores. Herein, sono-responsive nanoparticles coated with DC-targeted antibody chimeric cancer cell membrane are investigated for multimodal therapy. The nanometal organic frameworks (MOFs) that respond to ultrasound are loaded successfully inside the vesicles displaying an anti-DEC205 antibody. The anti-DEC205 chimeric vesicles can directly target and activate DCs, promote tumor antigens cross-presentation, and then produce a cascade amplified T-cell immune response. Upon deep tissue-penetrating sonication, AMR-MOF@AuPt generates large amounts of reactive oxygen species that directly kill cancer cells, further initiating an anti-cancer T cell immune response. Such synergistic sono-immunotherapies effectually inhibit tumor growth and induce strong systemic and long-term immune memory against cancer recurrence and distant metastasis. The authors findings provide DCs and tumor cells of a dual active-targeting cell membrane-coated sono-immunotherapeutic nanoplatform for cancer therapy.

A phase I/Ib trial and biological correlate analysis of neoadjuvant SBRT with single-dose durvalumab in HPV-unrelated locally advanced HNSCC

Five-year survival for human papilloma virus-unrelated head and neck squamous cell carcinomas remain below 50%. We assessed the safety of administering combination hypofractionated stereotactic body radiation therapy with single-dose durvalumab (anti-PD-L1) neoadjuvantly (n = 21) ( NCT03635164 ). The primary endpoint of the study was safety, which was met. Secondary endpoints included radiographic, pathologic and objective response; locoregional control; progression-free survival; and overall survival. Among evaluable patients at an early median follow-up of 16 months (448 d or 64 weeks), overall survival was 80.1% with 95% confidence interval (95% CI) (62.0%, 100.0%), locoregional control and progression-free survival were 75.8% with 95% CI (57.5%, 99.8%), and major pathological response or complete response was 75% with 95% exact CI (51.6%, 100.0%). For patients treated with 24 Gy, 89% with 95% CI (57.1%, 100.0%) had MPR or CR. Using high-dimensional multi-omics and spatial data as well as biological correlatives, we show that responders had: (1) an increase in effector T cells; (2) a decrease in immunosuppressive cells; and (3) an increase in antigen presentation post-treatment.

Case report: Patient specific combination of surgery and immunotherapy in advanced squamous cell carcinoma of the head and neck - a case series and review of literature

BACKGROUND

Prognosis of patients with recurrent or metastatic head and neck cancer is generally poor. Adjuvant immunotherapy (IT) featuring immune checkpoint inhibition (ICI) is standard of care in advanced stage head and neck squamous cell carcinoma (HNSCC) and cutaneous squamous cell carcinoma (CSCC). ICI response rates in CSCC are described as higher than in HNSCC. IT is constantly shifting into earlier disease stages which confronts the surgeon with immunotherapeutically pre-treated patients. It is therefore becoming increasingly difficult to assess which patients with symptomatic tumor disease and a lack of curative surgical option might benefit from salvage surgery.

CASE PRESENTATIONS

The following 6 cases describe therapeutic decision-making regarding ICI and (salvage) surgery in patients with advanced stage HNSCC or CSCC. Cases A and B focus on neoadjuvant ICI followed by salvage surgery. In Cases C and D salvage surgery was performed after short-term stabilization with partial response to ICI. The last two cases (Cases E and F) address the surgical approach after failure of ICI. All cases are discussed in the context of the current study landscape and with focus on individual decision-making. For better understanding, a timetable of the clinical course is given for each case.

CONCLUSIONS

ICI is rapidly expanding its frontiers into the neoadjuvant setting, frequently confronting the surgeon with heavily pretreated patients. Salvage surgery is a viable therapeutic concept despite the rise of systemic treatment options. Decision-making on surgical intervention in case of a salvage surgery remains an individual choice. For neoadjuvant ICI monitoring regarding pathological tumor response or tumor necrosis rate, we suggest correlation between the initial biopsy and the definite tumor resectate in order to increase its significance as a surrogate marker. Scheduling of neoadjuvant ICI should be further investigated, as recent studies indicate better outcomes with shorter time frames.

Immunotherapy in head and neck squamous cell carcinoma: An updated review

Squamous cell cancer of the head and neck (HNSCC) is the sixth most common cancer and is associated with significant morbidity and mortality. The tumor microenvironment for HNSCC is a complex interplay of immune cells, stromal cells, and cytokines amongst others. Immunotherapy acts as an effective antineoplastic agent by influencing this complex environment and includes immune checkpoint inhibitors (ICI). ICI have been approved in the frontline setting for recurrent and metastatic (R/M) HNSCC as well as platinum-refractory (second line) R/M HNSCC. However, recent clinical studies highlight that the response to immunotherapy varies, and different ICI, as well as different combination strategies play a crucial role in augmenting the efficacy of immunotherapy. An in-depth analysis and focused study of the immune contexture in patients with HNSCC receiving ICI remains critical. Many novel immunotherapies including CAR-T cell therapy, oncolytic virus therapy, and vaccines are underway. Ongoing trials are testing ICI in the neoadjuvant and adjuvant settings. Furthermore, identifying better biomarkers to target population that benefits from immunotherapy is of paramount importance. Pioneering the optimal combination regimen utilizing new novel immunotherapy has recently become a paradigm shift in the HNSCC treatment landscape. Herein, we summarize the clinical development with all ongoing clinical trials of immunotherapy in HNSCC.

Moving beyond the T cell synapse for combination neoadjuvant immunotherapy in head and neck cancer

Patients with HPV-unrelated head and neck squamous cell carcinoma (HPV-unrelated HNSCC) show only modest benefit from treatment with PD-1 inhibitors (PD-1i). Targeting transforming growth factor β (TGF-β) may make PD-1i more effective by inducing T cell responses. In this issue of the JCI, Redman et al. performed a clinical trial in 14 patients with HPV-unrelated HNSCC using bintrafusp alfa, a bifunctional fusion protein that blocks PD-L1 and TGF-β. Primary tumors displayed pathologic responses with 5 of 14 patients having at least a partial response. While no primary tumor or metastatic lymph node demonstrated a complete pathologic response, the findings suggest that concurrent neoadjuvant inhibition of PD-L1 and TGF-β may provide a rational strategy to improve pathologic response and clinical outcome in patients with HPV-unrelated HNSCC.

A pilot study of neoadjuvant combination of anti-PD-1 camrelizumab and VEGFR2 inhibitor apatinib for locally advanced resectable oral squamous cell carcinoma

Novel neoadjuvant therapy regimens are warranted for oral squamous cell carcinoma (OSCC). In this phase I trial (NCT04393506), 20 patients with locally advanced resectable OSCC receive three cycles of camrelizumab (200 mg, q2w) and apatinib (250 mg, once daily) before surgery. The primary endpoints are safety and major pathological response (MPR, defined as ≤10% residual viable tumour cells). Secondary endpoints include 2-year survival rate and local recurrence rate (not reported due to inadequate follow-up). Exploratory endpoints are the relationships between PD-L1 combined positive score (CPS, defined as the number of PD-L1-stained cells divided by the total number of viable tumour cells, multiplied by 100) and other immunological and genomic biomarkers and response. Neoadjuvant treatment is well-tolerated, and the MPR rate is 40% (8/20), meeting the primary endpoint. All five patients with CPS ˃10 achieve MPR. Post-hoc analysis show 18-month locoregional recurrence and survival rates of 10.5% (95% CI: 0%–24.3%) and 95% (95% CI: 85.4%–100.0%), respectively. Patients achieving MPR show more CD4+ T-cell infiltration than those without MPR (P = 0.02), and decreased CD31 and ɑ-SMA expression levels are observed after neoadjuvant therapy. In conclusion, neoadjuvant camrelizumab and apatinib is safe and yields a promising MPR rate for OSCC.

In patients with locally advanced resectable oral squamous cell carcinoma (OSCC), the risk of recurrence and metastasis following treatment is high. Here, a phase I clinical trial reports safety and pathological response of neoadjuvant camrelizumab and apatinib in patients with locally advanced resectable OSCC.

The paradox of radiation and T cells in tumors

In this review we consider what appears to be a paradox in immunotherapies based around radiation therapy. The paradox is based on three main points. 1. That T cells are needed for radiation's efficacy; 2. That tumor-specific T cells are enriched in the field of treatment; and 3. That radiation kills T cells in the treatment field. We discuss evidence of the effect of radiation on T cells in the field given their ongoing movement in and out of tissues and the tumor, and how the movement of T cells impacts the treated primary tumor and untreated distant metastases. Given this evidence, we revisit the paradox to understand how the extraordinary efficacy of radiation and immunity in preclinical models is dependent on this radiation sensitive cell.

[Immuno-radiotherapy: A review of the rationale, recent clinical developments and future prospects]

Thanks to the success of checkpoint inhibitors, immunotherapy now plays a major role in the management of a large number of solid tumors, while the number of indications continues to grow and new combinations could, in the near future, further modify treatment standards. However, the response rates of immunotherapies as monotherapy are modest and their use is increasingly considered in combination with other cancer treatments (chemotherapy, surgery, radiotherapy or certain targeted therapies). Combinations with radiotherapy seem particularly attractive because there is a strong experimental rationale linking part of the efficacy of ionizing radiation to an induced stimulation of both of the innate and adaptive response. Many early phases and a number of large randomized combination trials have published efficacy and safety results, while important trials are still ongoing and will provide answers in the near future. This short review recalls the experimental biological rationale for immuno-radiotherapy and highlights some of the fundamental directions being explored, then presents the clinical efficacy and safety results available to date, those expected in the near future, and finally outlines the outlook in this rapidly evolving field.

Radioimmunotherapy in HPV-Associated Head and Neck Squamous Cell Carcinoma

HPV-associated head and neck squamous cell carcinoma (HNSCC) is a cancer entity with unique biological and clinical characteristics that requires more personalized treatment strategies. As the backbone of conventional therapeutics, radiation is now harnessed to synergize with immunotherapy in multiple malignancies. Accumulating preclinical and clinical data have suggested the potential of radioimmunotherapy in eliciting local and systemic anti-tumor response via direct killing of tumor cells and immunogenic cell death. However, this effect remains uncertain in HPV-associated HNSCC. Owing to its intrinsic radiosensitivity and distinct tumor microenvironment, HPV-associated HNSCC may represent a good candidate for radioimmunotherapy. In this review, we provide a detailed illustration of the biology, the genomic features, and immune landscapes of HPV-associated HNSCC that support the synergism between radiation and immune agents. The interaction between radiotherapy and immunotherapy is described. We also highlight the present evidence as well as ongoing trials using different combination strategies in the recurrent/metastatic or definitive settings. In addition, we have summarized the challenges and outlook for future trial design, with special emphasis on radiotherapy optimization and novel therapeutic options to incorporate.

Neoadjuvant immunoradiotherapy in patients with locally advanced oral cavity squamous cell carcinoma: a retrospective study

BACKGROUND

Although anti-programmed death receptor-1 (PD-1) agents have been evaluated in the neoadjuvant setting for the treatment of locally advanced head and neck cancer, including oral cavity squamous cell carcinoma (OCSCC), the overall response rate is modest. The aim of the present study was to evaluate the efficacy and safety of neoadjuvant nivolumab in combination with stereotactic body radiotherapy (SBRT) for the treatment of locally advanced OCSCC.

METHODS

OCSCC patients who underwent surgical resection within 6 months of treatment with nivolumab plus SBRT from December 2018 to February 2021 were analyzed retrospectively.

RESULTS

All 30 eligible patients enrolled in this study well tolerated the neoadjuvant treatment with no serious adverse events (AEs). Of them, 27 patients (90.0%) achieved R0 resection, and 5 patients (16.7%) experienced procedure-associated complications. The complete response (CR), partial response (PR) and stable disease (SD) were 10.0%, 46.7% and 43.3% respectively. The major pathological response (MPR), complete pathological response (pCR) and clinical to pathological downstaging rate were 60.0%, 33.3% and 83.3% respectively. During the median follow-up period of 13.5 months, 26 patients (86.7%) who underwent surgical resection remained alive. The disease-free survival (DFS) and overall survival (OS) at 24 months were 70.4% and 76.4% respectively.

CONCLUSIONS

Neoadjuvant nivolumab plus SBRT is safe and efficacious, and could be used as a potential neoadjuvant option for the treatment of patients with locally advanced OCSCC.

Neoadjuvant Chemoimmunotherapy for the Treatment of Locally Advanced Head and Neck Squamous Cell Carcinoma: A Single-Arm Phase 2 Clinical Trial

PURPOSE

This study aimed to assess the antitumor activity and safety of neoadjuvant chemotherapy combined with PD-1 inhibitor camrelizumab in patients with locally advanced head and neck squamous cell carcinoma (HNSCC).

PATIENTS AND METHODS

In this single-center, single-arm, phase 2 trial, patients with resectable stage III-IVB HNSCC received chemotherapy [albumin-bound paclitaxel 260 mg/m2 (or docetaxel 75 mg/m2) plus cisplatin 75 mg/m2] and camrelizumab 200 mg on day 1 of each 21-day cycle for three cycles, followed by surgery, and adjuvant radiotherapy. Co-primary end points were pathological complete response (pCR) rate and safety.

RESULTS

Thirty patients were enrolled and completed the neoadjuvant therapy, with an objective response rate (ORR) of 96.7% (29/30). Twenty-seven patients underwent surgery without delay, with an R0 resection rate of 92.6% (25/27). The clinical to pathological downstaging rate was 100% (27/27). The pCR rate was 37.0% [95% confidence interval (CI), 19.4%-57.6%], and the major pathological response (MPR) rate was 74.1% (95% CI, 53.7%-88.9%). The median follow-up duration was 16.1 months (range, 8.3-28.5), and the disease-free survival rate at 12 months was 95.8% (95% CI, 73.9%-99.4%). Grade 3 neoadjuvant therapy-related adverse events included rash (1; 3.3%), pruritis (1; 3.3%), and thrombocytopenia (1; 3.3%), and no grade 4 or 5 treatment-related events occurred. The most common surgical complication was delayed wound healing (5; 18.5%).

CONCLUSIONS

Neoadjuvant chemotherapy plus camrelizumab for locally advanced HNSCC showed high ORR, pCR, and MPR rates, with an acceptable safety profile. These data support further evaluation of neoadjuvant chemoimmunotherapy for the treatment of locally advanced HNSCC.

Lymphatic-preserving treatment sequencing with immune checkpoint inhibition unleashes cDC1-dependent antitumor immunity in HNSCC

Despite the promise of immune checkpoint inhibition (ICI), therapeutic responses remain limited. This raises the possibility that standard of care treatments delivered in concert may compromise the tumor response. To address this, we employ tobacco-signature head and neck squamous cell carcinoma murine models in which we map tumor-draining lymphatics and develop models for regional lymphablation with surgery or radiation. We find that lymphablation eliminates the tumor ICI response, worsening overall survival and repolarizing the tumor- and peripheral-immune compartments. Mechanistically, within tumor-draining lymphatics, we observe an upregulation of conventional type I dendritic cells and type I interferon signaling and show that both are necessary for the ICI response and lost with lymphablation. Ultimately, we provide a mechanistic understanding of how standard oncologic therapies targeting regional lymphatics impact the tumor response to immune-oncology therapy in order to define rational, lymphatic-preserving treatment sequences that mobilize systemic antitumor immunity, achieve optimal tumor responses, control regional metastatic disease, and confer durable antitumor immunity.

Preoperative immunotherapy for head and neck cancers: state of art

PURPOSE OF REVIEW

Programmed cell death 1 (PD-l)-targeting agents have been FDA-approved for treatment of recurrent/ metastatic head and neck squamous cell carcinoma (HNSCC). Clinical studies employing these agents preoperatively for HNSCC in the definitive setting are emerging and have important implications.

RECENT FINDINGS

Preclinical studies demonstrate enhanced effectiveness of preoperative PD-1 targeting compared with postoperative treatment. Nine HNSCC clinical studies evaluating preoperative treatment with PD-1-targeted pembrolizumab/nivolumab alone or in combination therapy were recently reported. These studies differed by preoperative treatment type and duration and reported no surgical delays, no unexpected surgical complications and grade 3-4 immune-related adverse events consistent with the employed immunotherapeutic agent(s). Rates of major pathologic response (MPR), reduced residual viable tumour to 10% or less, ranged from 2.9-31% across eight trials without neoadjuvant radiation therapy. Higher PD-1 ligand (PD-L1) expression, increased inflammatory gene expression and enhanced immune cell tumour infiltration in baseline biopsies were associated with pathologic tumour response (pTR) in some studies. Any degree of pTR was associated with improved survival/relapse outcomes in two studies.

SUMMARY

Emerging preoperative anti-PD-1 HNSCC clinical studies indicate that preoperative treatment does not impact surgical management. Defining predictive biomarkersand tumour pathologic response implications for patient survival are areas for further investigation.

Introducing Checkpoint Inhibitors Into the Curative Setting of Head and Neck Cancers: Lessons Learned, Future Considerations

The emergence of immunotherapy, in the form of immune checkpoint inhibitors, has irrevocably altered the paradigm of cancer treatment over the past decade. Multiple characteristics of the immune landscape in head and neck squamous cell carcinoma suggest a strong rationale for the use of immunotherapies in this disease. Data from studies with both single-agent immunotherapies and chemotherapy and immunotherapy combinations in patients with incurable, relapsed disease have confirmed the potential for immune checkpoint inhibitors to be translated into settings in which patients with head and neck squamous cell carcinoma are treated with curative intent. Indeed, a number of single-arm and randomized studies, including trials of immunotherapy with surgery, chemotherapy, or radiotherapy, have already been completed or are ongoing. In this review, we present promising data from studies in which immunotherapy has been used in conjunction with curative-intent surgery, both as neoadjuvant/induction treatment and as an adjuvant approach. In addition, we discuss the fact that immune checkpoint inhibitor therapy is, once again, allowing oncologists to revisit the potential role of neoadjuvant chemotherapy as part of definitive treatment regimens for patients with locally advanced head and neck squamous cell carcinoma. Finally, we address the increasing interest in exploiting synergistic interactions between radiotherapy and immunotherapy in the context of radical radiotherapy and chemoradiotherapy regimens. As a consequence of these new areas of research, we are optimistic that the next decade may see immunotherapy embedded within recommended standard-of-care curative regimens for patients with locally advanced head and neck squamous cell carcinoma.

Perioperative Outcomes of Minimally Invasive Esophagectomy After Neoadjuvant Immunotherapy for Patients With Locally Advanced Esophageal Squamous Cell Carcinoma

Background

Immunotherapy has become a pillar of advanced solid tumors treatment. Patients are more likely to benefit from neoadjuvant immunotherapy compared with traditional neoadjuvant therapy. However, the safety and efficacy of neoadjuvant immunotherapy for the treatment of locally advanced, surgically resectable Esophageal squamous cell carcinoma (ESCC) remain unknown.

Method

ESCC patients who received neoadjuvant treatment following minimally invasive esophagogastrostomy were enrolled from June 2020 to September 2021. The characteristics of neoadjuvant treatment and surgery were investigated to determine the safety and efficacy of the neoadjuvant combination of chemotherapy and immunotherapy (NCI).

Results

A total of 149 patients were included in the study. Patient ratio was 40:109 between NCI and neoadjuvant chemotherapy plus radiotherapy (NCR) groups. No significant difference was found in terms of pathological characteristics, including ypN stage, ypTNM stage, differentiation, lymphovascular invasion, perineural invasion, pathological complete regression and tumor regression score, and these parameters were not correlated with NCI or NCR (all p>0.05). Regarding to the operation, the NCI group had less blood loss (49.25 ± 13.47 vs. 57.02 ± 47.26, p<0.001), and shorter operation time (247.75 ± 28.28 vs. 285.83 ± 52.43, p<0.001) than the NCR group. Additionally, the NCI group demonstrated a lower rate of overall perioperative complications (p=0.003) and grade >2 perioperative complications (p=0.042) than the NCR group.

Conclusion

Overall, the findings reported here indicate NCI could result in better outcome and less complications to locally advanced ESCC patients compared with NCR therapy. As a novel therapeutic option, the efficacy and safety of NCI appears to be feasible and safe, while long-term survival data is still needed.

Neoadjuvant Immunotherapy Strategies in HPV-Related Head-and-Neck Cancer

Purpose of review

Herein, we review current evidence and future directions of neoadjuvant immunotherapy in HPV-related head and neck squamous cell carcinoma (HNSCC) by describing published data and ongoing clinical trials.

Recent findings

Although HNSCCs have shown response to immune checkpoint inhibitors in recurrent/metastatic disease, a limited number of patients benefit from this treatment. There is an expanding interest in clarifying the clinical benefit of immunotherapy in earlier stage disease setting including at initial presentation. Neoadjuvant immunotherapy for HPV-related HNSCCs represents a rational approach, as these cancers bear strong viral antigens.

Summary

The majority of patients with HPV-related HNSCC have good prognosis and treatment de-intensification strategies are under evaluation to decrease toxicity and maintain efficacy. On the other hand, a subset of patients with HPV-related HNSCC have a poorer prognosis and additional treatment options are need to improve outcome. Multiple clinical trials are ongoing to evaluate whether neoadjuvant immunotherapy will achieve these goals.

HPV-associated oropharyngeal cancer: epidemiology, molecular biology and clinical management

Human papillomavirus (HPV)-positive (HPV⁺) oropharyngeal squamous cell carcinoma (OPSCC) has one of the most rapidly increasing incidences of any cancer in high-income countries. The most recent (8th) edition of the UICC/AJCC staging system separates HPV⁺ OPSCC from its HPV-negative (HPV⁻) counterpart to account for the improved prognosis seen in the former. Indeed, owing to its improved prognosis and greater prevalence in younger individuals, numerous ongoing trials are examining the potential for treatment de-intensification as a means to improve quality of life while maintaining acceptable survival outcomes. In addition, owing to the distinct biology of HPV⁺ OPSCCs, targeted therapies and immunotherapies have become an area of particular interest. Importantly, OPSCC is often detected at an advanced stage owing to a lack of symptoms in the early stages; therefore, a need exists to identify and validate possible diagnostic biomarkers to aid in earlier detection. In this Review, we provide a summary of the epidemiology, molecular biology and clinical management of HPV⁺ OPSCC in an effort to highlight important advances in the field. Ultimately, a need exists for improved understanding of the molecular basis and clinical course of this disease to guide efforts towards early detection and precision care, and to improve patient outcomes.

The incidence of human papillomavirus (HPV)-positive oropharyngeal squamous cell carcinoma (OPSCC) is increasing rapidly in most developed countries. In this Review, the authors provide an overview of the epidemiology, molecular biology and treatment of HPV-positive OPSCC, including discussions of the role of treatment de-escalation and emerging novel therapies.

The incidence of human papillomavirus-associated oropharyngeal cancer (HPV⁺ OPSCC) is expected to continue to rise over the coming decades until the benefits of gender-neutral prophylactic HPV vaccination begin to become manifest.

The incidence of HPV⁺ OPSCC appears to be highest in high-income countries, although more epidemiological data are needed from low- and middle-income countries, in which HPV vaccination coverage remains low.

The substantially better prognosis of patients with HPV⁺ OPSCC compared to those with HPV^– OPSCC has been recognized in the American Joint Committee on Cancer TNM8 staging guidelines, which recommend stratification by HPV status to improve staging.

The molecular biology and genomic features of HPV⁺ OPSCC are similar to those of other HPV-associated malignancies, with HPV oncogenes (E6 and E7) acting as key drivers of pathogenesis.

Treatment de-intensification is being pursued in clinical trials, although identifying the ~15% of patients with HPV⁺ OPSCC who have recurrent disease, and who therefore require more intensive treatment, remains a key challenge.

Prospective Clinical Investigation of the Efficacy of Combination Radiation Therapy With Immune Checkpoint Inhibition

Immune checkpoint inhibitors (ICIs) lead to durable responses in a subset of patients with cancer, but most patients do not respond to ICI, prompting interest in combining immunotherapy with other therapeutic regimens. Preclinical evidence supports the potential for therapeutic synergy between immunotherapy and radiation therapy through modulation of the tumor microenvironment and antitumor immune responses. Local therapy also has the potential to overcome localized sites of relative immune suppression and resistance. Prospective clinical trials have been initiated to test these hypotheses in the clinic as well as to investigate the toxicities and adverse events associated with combination immunotherapy and radiation therapy. In this review, we discuss the emerging results from prospective clinical trials of combination immunotherapy and radiation therapy, the safety and efficacy of their combination, concordance with preclinical and retrospective data, and some of the remaining open questions to be addressed by future clinical trials.

Humanized Mice as a Valuable Pre-Clinical Model for Cancer Immunotherapy Research

Immunotherapy with checkpoint inhibitors opened new horizons in cancer treatment. Clinical trials for novel immunotherapies or unexplored combination regimens either need years of development or are simply impossible to perform like is the case in cancer patients with limited life expectancy. Thus, the need for preclinical models that rapidly and safely allow for a better understanding of underlying mechanisms, drug kinetics and toxicity leading to the selection of the best regimen to be translated into the clinic, is of high importance. Humanized mice that can bear both human immune system and human tumors, are increasingly used in recent preclinical immunotherapy studies and represent a remarkably unprecedented tool in this field. In this review, we describe, summarize, and discuss the recent advances of humanized mouse models used for cancer immunotherapy research and the challenges faced during their establishment. We also highlight the lack of preclinical studies using this model for radiotherapy-based research and argue that it can be a great asset to understand and answer many open questions around radiation therapy such as its presumed associated "abscopal effect".

Kickstarting Immunity in Cold Tumours: Localised Tumour Therapy Combinations With Immune Checkpoint Blockade

Cancer patients with low or absent pre-existing anti-tumour immunity ("cold" tumours) respond poorly to treatment with immune checkpoint inhibitors (ICPI). In order to render these patients susceptible to ICPI, initiation of de novo tumour-targeted immune responses is required. This involves triggering of inflammatory signalling, innate immune activation including recruitment and stimulation of dendritic cells (DCs), and ultimately priming of tumour-specific T cells. The ability of tumour localised therapies to trigger these pathways and act as in situ tumour vaccines is being increasingly explored, with the aspiration of developing combination strategies with ICPI that could generate long-lasting responses. In this effort, it is crucial to consider how therapy-induced changes in the tumour microenvironment (TME) act both as immune stimulants but also, in some cases, exacerbate immune resistance mechanisms. Increasingly refined immune monitoring in pre-clinical studies and analysis of on-treatment biopsies from clinical trials have provided insight into therapy-induced biomarkers of response, as well as actionable targets for optimal synergy between localised therapies and ICB. Here, we review studies on the immunomodulatory effects of novel and experimental localised therapies, as well as the re-evaluation of established therapies, such as radiotherapy, as immune adjuvants with a focus on ICPI combinations.

The Abscopal Effect: A Review of Pre-Clinical and Clinical Advances

Radiotherapy has been used for more than a hundred years to cure or locally control tumors. Regression of tumors outside of the irradiated field was occasionally observed and is known as the abscopal effect. However, the occurrence of systemic anti-tumor effects was deemed too rare and unpredictable to be a therapeutic goal. Recent studies suggest that immunotherapy and radiation in combination may enhance the abscopal response. Increasing numbers of cases are being reported since the routine implementation of immune checkpoint inhibitors, showing that combined radiotherapy with immunotherapy has a synergistic effect on both local and distant (i.e., unirradiated) tumors. In this review, we summarize pre-clinical and clinical reports, with a specific focus on the mechanisms behind the immunostimulatory effects of radiation and how this is enhanced by immunotherapy.

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.

Immunotherapy for Head and Neck Cancer: A Paradigm Shift From Induction Chemotherapy to Neoadjuvant Immunotherapy

Neoadjuvant immunotherapy has the potential to enhance clinical outcomes by increasing anti-tumor immune responses in the presence of abundant tumor-derived antigen in an immune microenvironment that has not been exposed to previous therapy. The current mainstay of advanced head and neck squamous cell carcinoma (HNSCC) treatment remains surgery and radiotherapy with/without conventional chemotherapy. Despite this multi-modality treatment, advanced human papillomavirus (HPV)-negative HNSCC shows poor prognosis. Treatment intensification with neoadjuvant (induction) chemotherapies with platinum drugs are insufficient to significantly prolong overall survival. Although only 15-20% of patients benefit, immunotherapies have been approved and widely used for recurrent and metastatic HNSCC. These successes have led to checkpoint blockade therapies being testing in earlier treatment settings. Recent clinical trials of neoadjuvant immunotherapy show promising results and this methodology has the potential to change the treatment algorithm of HNSCC. This overview examines the treatment history of neoadjuvant approaches for HNSCC, and especially focuses on the recent topics of neoadjuvant immunotherapy for HNSCC.