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Pembrolizumab as monotherapy or in combination with chemotherapy is a standard of care in patients (pts) with recurrent/metastatic (R/M) head and neck squamous cell carcinoma (HNSCC) and PD-L1 CPS ≥1. While pembrolizumab monotherapy results in low response rates, the addition of 5FU/cisplatin adds significant toxicity for pts. Rational combinations which improve outcomes while avoiding cytotoxic chemotherapy are needed. HNSCC is associated with overexpression of VEGFR, MET, and AXL, and there are preclinical data supporting the antitumor effect of inhibition of these kinases through suppressing tumor growth and angiogenesis, and promoting an immune-permissive tumor microenvironment. In a phase 2 study, pembrolizumab plus the multi-kinase inhibitor cabozantinib demonstrated encouraging clinical activity and safety in pts with R/M HNSCC (Saba et al. Nat Med 2023), suggesting that targeting kinases including VEGFR, MET, and AXL has antitumor effect in this population and may enhance responses to immune checkpoint inhibitor (ICIs). Zanzalintinib (XL092) is a novel, multi-targeted kinase inhibitor that inhibits VEGFR, MET, and the TAM kinases (TYRO3, AXL, MER). STELLAR-305 (NCT06082167) is a randomized, double-blind, phase 2/3 study that will evaluate the efficacy and safety of zanzalintinib plus pembrolizumab vs pembrolizumab plus placebo in pts with previously untreated, PD-L1-positive, R/M HNSCC. Eligible pts are aged ≥18 years and have histologically or cytologically confirmed R/M HNSCC that is incurable with local therapy and has not been treated with systemic therapy, unless completed >6 months before randomization and given as part of multimodal treatment for locally advanced disease. Pts must have a primary tumor location of the oropharynx (HPV testing required), oral cavity, hypopharynx, or larynx; pts with nasopharynx, salivary gland, or occult primary sites are excluded. Other eligibility criteria include a PD-L1 CPS ≥1; measurable disease per RECIST v1.1; and an ECOG performance status of 0–1. Prior treatment with ICIs or zanzalintinib is not allowed. Patients will be randomized 1:1 to either zanzalintinib plus pembrolizumab or placebo plus pembrolizumab. The dual primary endpoints are PFS per RECIST v1.1 by blinded independent radiology committee and overall survival. Secondary endpoints include safety, PFS per RECIST v1.1 by investigator, objective response rate, and duration of response. If minimum efficacy requirements are met in phase 2, the study will proceed to phase 3. In total, approximately 500 pts will be enrolled across phase 2 and 3. The study is ongoing with enrollment planned across sites in US, Europe, and the Asia-Pacific region. TBD TBD [ABSTRACT FROM AUTHOR]

The combination of radiotherapy and immune checkpoint inhibitors (ICIs) has been shown to exert synergistic anti-tumor effects in various tumors. In esophageal squamous cell carcinoma (ESCC), several clinical trials of radiotherapy combined with ICIs are undergoing or have been finished. However, the efficacy and action mechanisms of radiotherapy combined with ICIs is still not clear in ESCC. Our study aimed to investigate whether radiotherapy improved the anti-cancer effect of PD-L1 antibody and the effect of this combination therapy on tumor-immune microenvironment. The mouse esophageal cancer cell line mEC25 was implanted into the armpits of female C57 mice. When the tumor volume grew to 150-250 mm3, the mice were randomly divided into different groups including control group (administration of IgG antibody), radiotherapy group (12 Gy at 4 Gy per fraction), PD-L1 antibody group (200 mg/kg i.p. for three times) and combination group (fractionated radiation combined with PD-L1 antibody was delivered on day 1, day 4 and day 7, the day when fractionated radiation began was recorded as day 1).The mice were sacrificed on the 1st, 3rd and 7th day after the treatment was ended. The tumor, spleen and draining lymph nodes of the mice were collected and analyzed using flow cytometry (FCM), and the tumor volume and survival time of mice were calculated. Compared with radiotherapy or PD-L1 antibody alone, the combination therapy significantly prolonged the survival time of mice and decreased the growth rate of xenograft tumors FCM analysis showed that the combination therapy significantly increased the infiltration and cytotoxicity of effector T cells and reduced the proportion of M2 macrophages in tumor, spleen and lymph nodes. In addition, in tumor and spleen, the proportion of regulatory T cells (Tregs) decreased in the group of combination therapy. In tumor, spleen, and lymph nodes, the proportion of central memory T cell (TCM) was increased in the group of combination therapy. The anti-tumor effect of radiotherapy combined with PD-L1 antibody is superior to single treatment in the mouse model of esophageal cancer. Radiotherapy can shape tumor-immune microenvironment, allowing the infiltration of effector T cells and exclusion of immune-suppressive cells such as M2 macrophages and Tregs. [ABSTRACT FROM AUTHOR]

The treatment of anal squamous cell carcinoma (SCC) with definitive radiotherapy (RT)/chemoradiotherapy (CRT) has a high likelihood of success; nevertheless, treatment resistance and recurrence rates cannot be ignored. Therefore, we aimed to identify the relationship between immunohistochemical (IHC) evaluation, treatment response, and prognosis. This retrospective study included 42 patients with anal SCC treated with definitive RT/CRT at a single institution between 2006 and 2020. Detection of high-risk HPV-DNA and IHC analysis of p16, p53, and PD-L1 expression was performed from diagnostic formalin-fixed, paraffin-embedded (FFPE) biopsies. Positive staining was accepted as >5% in tumor cells for p16 and p53 expression in addition to ≥1% combined positive score (CPS) [(PD-L1 positive tumor, lymphocyte, macrophage count/total viable cell count) x100] for PD-L1 expression. Thirty patients (71.4%) had a complete response to definitive RT/CRT. Recurrence was observed in 16 (38.1%) patients, with 3 (7.1%) having locoregional recurrence (LRR), 6 (14.3%) having distant metastases (DM), and 7 (16.7%) having both LRR and DM. Twenty-four (57.1%) patients were alive. Thirty (71.4%) patients were HPV+, while 12 (28.6%) were HPV-. There was a significant correlation between HPV+ and p16+ status (p<0.001). HPV- status was associated with the male gender (p = 0.001). HPV- and p16- status were significantly associated with a lack of complete response to definitive RT/CRT (p<0.001, p<0.001, respectively). Furthermore, there was a significant relationship between lack of complete response and increased recurrence (p = 0.016) and distant metastases (p = 0.015). Ten of the 16 patients with recurrence were p53+; a significant correlation was found between recurrence and p53+ status (p = 0.006). Similarly, p53+ status was associated with increased LRR (p = 0.014). PD-L1 CPS ≥ 1% was found in 31 (73.8%) patients. PD-L1 positivity was significantly correlated with HPV+ (p = 0.026) and p16+ (p = 0.013) status. All 10 (23.8%) patients with LRR were PD-L1+; PD-L1 CPS ≥ 1% was associated with poor local control (p = 0.031). In univariate analysis, age [<65] (p = 0.049), complete response (p = 0.015), and HPV+ status (p = 0.010) were related to increased 5-year (y) overall survival (OS); complete response (p = 0.001), HPV+ status (p = 0.025) and p53- status (p = 0.010) were associated with increased 5-y disease-free survival (DFS). In multivariate analysis, age [<65] (p = 0.010) and HPV+ status (p = 0.002) were significant prognostic factors for 5-y OS, whereas complete response (p = 0.007) and p53- status (p = 0.038) were significant prognostic factors for 5-y DFS. Patients with HPV- status and/or poor prognostic biomarkers should be identified at diagnosis. Thus, better outcomes can be achieved with different treatment options, such as combining immunotherapy and standard CRT. [ABSTRACT FROM AUTHOR]

Immunotherapy with checkpoint inhibitors (ICI) improved survival in HNSCC. Response rates to ICIs remain low, in part due to lack of effective predictors of response to guide patients' selection. PD-L1, as the only biomarker used in prospective research of ICI in HNSCC has generated inconsistent results. Developments in Precision Oncology in HNSCC brings the prospect for new biomarkers. Tumor mutational burden (TMB) is under investigation in many solid tumors and this study assessed the significance and potential role of TMB and PD-L1 in the immunotherapy of HNSCC. This single institution retrospective review includes HNSCC patients (pts) with tumor tissue evaluated for PD-L1 (IHC 22C3 pharmDx kit) and TMB by FoundationOne. PD-L1 was reported as TPS score (prior to 2018) or CPS score (thereafter). TMB and PD-L1 were analyzed for individual association with demographics, disease characteristics and survival, and with progression free survival (PFS) and response to ICI. Pts tested for TMB (mut/Mb) were grouped as TMB(1-5) and TMB(6+) and pts tested for PD-L1 were grouped as PD-L1(0), PD-L1(1-19) and PD-L1(20+). 139 pts were included, 128 pts had TMB, 95 pts had PD-L1 and 92 pts had both results. TMB(6+) was associated with smoking (p=0.03) and with tumor location, with laryngeal cancer pts having higher TMB (p<0.01) and oropharyngeal cancer pts having lower TMB (p p<0.01). PD-L1 was higher in African Americans (p=0.04), in never smokers (p=0.04) and never drinkers (p=0.01), and in pts with earlier cancer stage (p=0.03) and lower tumor stage (p p<0.01). There was no correlation of TMB or PD-L1 with HPV status. TMB(6+) was associated with improved survival in univariate analysis (p=0.02) and in Cox proportional hazards regression model adjusted for age, tobacco, tumor site, nodal stage, previous chemo/radiotherapy and PD-L1 level (p<0.01). No correlation was found between PD-L1 level and prognosis. There was no correlation between TMB and PD-L1 level. Treatment efficacy with ICI was evaluated in 51 pts, of whom 40 pts had TMB and 36 pts had PD-L1 results. There was significant association of continuous TMB score with PFS (p=0.013) and with response to ICI (mean TMB=11.2 in responders and 4.9 in non-responders; p=0.01). Similarly, in categorical analysis, PFS was 538 days in TMB(6+) and 261 days in TMB(1-5) (p=0.04). There was no association between response to ICI or PFS and PD-L1 analyzed as categorical (p=0.89 and p=0.62) or continuous variable (p=0.99 and p=0.66). Inadequate PD-L1 results in this study could be explained by inconsistence in methods. The association of TMB with prognosis and response to ICI in this study warrants further investigations, and prompts a methodology harmonization effort and advancement of TMB in future prospective studies. The recent availability of circulating TMB makes it a further attractive biomarker. [ABSTRACT FROM AUTHOR]