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.

Changes in Circulating Tumor DNA Reflect Clinical Benefit Across Multiple Studies of Patients With Non-Small-Cell Lung Cancer Treated With Immune Checkpoint Inhibitors.

PURPOSE: As immune checkpoint inhibitors (ICI) become increasingly used in frontline settings, identifying early indicators of response is needed. Recent studies suggest a role for circulating tumor DNA (ctDNA) in monitoring response to ICI, but uncertainty exists in the generalizability of these studies. Here, the role of ctDNA for monitoring response to ICI is assessed through a standardized approach by assessing clinical trial data from five independent studies. PATIENTS AND METHODS: Patient-level clinical and ctDNA data were pooled and harmonized from 200 patients across five independent clinical trials investigating the treatment of patients with non-small-cell lung cancer with programmed cell death-1 (PD-1)/programmed death ligand-1 (PD-L1)-directed monotherapy or in combination with chemotherapy. CtDNA levels were measured using different ctDNA assays across the studies. Maximum variant allele frequencies were calculated using all somatic tumor-derived variants in each unique patient sample to correlate ctDNA changes with overall survival (OS) and progression-free survival (PFS). RESULTS: We observed strong associations between reductions in ctDNA levels from on-treatment liquid biopsies with improved OS (OS; hazard ratio, 2.28; 95% CI, 1.62 to 3.20; P < .001) and PFS (PFS; hazard ratio 1.76; 95% CI, 1.31 to 2.36; P < .001). Changes in the maximum variant allele frequencies ctDNA values showed strong association across different outcomes. CONCLUSION: In this pooled analysis of five independent clinical trials, consistent and robust associations between reductions in ctDNA and outcomes were found across multiple end points assessed in patients with non-small-cell lung cancer treated with an ICI. Additional tumor types, stages, and drug classes should be included in future analyses to further validate this. CtDNA may serve as an important tool in clinical development and an early indicator of treatment benefit.

Therapeutic Intervention Using a Smad7-Based Tat Protein to Treat Radiation-Induced Oral Mucositis.

PURPOSE: Recent studies reported therapeutic effects of Smad7 on oral mucositis in mice without compromising radiation therapy-induced cancer cell killing in neighboring oral cancer. This study aims to assess whether a Smad7-based biologic can treat oral mucositis in a clinically relevant setting by establishing an oral mucositis model in dogs and analyzing molecular targets. METHODS AND MATERIALS: We created a truncated human Smad7 protein fused with the cell-penetrating Tat tag (Tat-PYC-Smad7). We used intensity modulated radiation therapy to induce oral mucositis in dogs and applied Tat-PYC-Smad7 to the oral mucosa in dose-finding studies after intensity modulated radiation therapy. Clinical outcomes were evaluated. Molecular targets were analyzed in biopsies and serum samples. RESULTS: Tat-PYC-Smad7 treatment significantly shortened the duration of grade 3 oral mucositis based on double-blinded Veterinary Radiation Therapy Oncology Group scores and histopathology evaluations. Topically applied Tat-PYC-Smad7 primarily penetrated epithelial cells and was undetectable in serum. NanoString nCounter Canine IO Panel identified that, compared to the vehicle samples, top molecular changes in Tat-PYC-Smad7 treated samples include reductions in inflammation and cell death and increases in cell growth and DNA repair. Consistently, immunostaining shows that Tat-PYC-Smad7 reduced DNA damage and neutrophil infiltration with attenuated TGF-ß and NFκB signaling. Furthermore, IL-1ß and TNF-α were lower in Tat-PYC-Smad7 treated mucosa and serum samples compared to those in vehicle controls. CONCLUSIONS: Topical Tat-PYC-Smad7 application demonstrated therapeutic effects on oral mucositis induced by intensity modulated radiation therapy in dogs. The local effects of Tat-PYC-Smad7 targeted molecules involved in oral mucositis pathogenesis as well as reduced systemic inflammatory cytokines.

The Clinical Cell-Cycle Risk (CCR) Score Is Associated With Metastasis After Radiation Therapy and Provides Guidance on When to Forgo Combined Androgen Deprivation Therapy With Dose-Escalated Radiation.

PURPOSE: The clinical cell-cycle risk (CCR) score, which combines the University of California, San Francisco's Cancer of the Prostate Risk Assessment (CAPRA) and the cell cycle progression (CCP) molecular score, has been validated to be prognostic of disease progression for men with prostate cancer. This study evaluated the ability of the CCR score to prognosticate the risk of metastasis in men receiving dose-escalated radiation therapy (RT) with or without androgen deprivation therapy (ADT). METHODS AND MATERIALS: This retrospective, multi-institutional cohort study included men with localized National Comprehensive Cancer Network (NCCN) intermediate-, high-, and very high-risk prostate cancer (N = 741). Patients were treated with dose-escalated RT with or without ADT. The primary outcome was time to metastasis. RESULTS: The CCR score prognosticated metastasis with a hazard ratio (HR) per unit score of 2.22 (95% confidence interval [CI], 1.71-2.89; P < .001). The CCR score better prognosticated metastasis than NCCN risk group (CCR, P < .001; NCCN, P = .46), CAPRA score (CCR, P = .002; CAPRA, P = .59), or CCP score (CCR, P < .001; CCP, P = .59) alone. In bivariable analyses, CCR score remained highly prognostic when accounting for ADT versus no ADT (HR, 2.18; 95% CI, 1.61-2.96; P < .001), ADT duration as a continuous variable (HR, 2.11; 95% CI, 1.59-2.79; P < .001), or ADT given at or below the recommended duration for each NCCN risk group (HR, 2.19; 95% CI, 1.69-2.86; P < .001). Men with CCR scores below or above the multimodality threshold (CCR score, 2.112) had a 10-year risk of metastasis of 3.7% and 21.24%, respectively. Men with below-threshold scores receiving RT alone had a 10-year risk of metastasis of 3.7%, and for men receiving RT plus ADT, the 10-year risk of metastasis was also 3.7%. CONCLUSIONS: The CCR score accurately and precisely prognosticates metastasis and adds clinically actionable information relative to guideline-recommended therapies based on NCCN risk in men undergoing dose-escalated RT with or without ADT. For men with scores below the multimodality threshold, adding ADT may not significantly reduce their 10-year risk of metastasis.

Distinct immune microenvironment profiles of therapeutic responders emerge in combined TGFß/PD-L1 blockade-treated squamous cell carcinoma.

Transforming growth factor beta (TGFß) and programmed death-ligand 1 (PD-L1) are often overproduced in refractory squamous cell carcinoma (SCC). We examined spatial patterns of PD-L1+ cells in mouse and human SCCs and found that PD-L1 was primarily expressed on infiltrating leukocytes. Although combined TGFß and PD-L1 blockade are undergoing cancer clinical trials, there are no predictive markers for therapeutic responders. To address this, we used both a small molecule TGFß inhibitor in combination with anti-PD-L1 and a bifunctional fusion protein targeting both TGFß and PD-L1 to treat mouse SCCs and found TGFß inhibition enhanced PD-L1 blockade-induced tumor eradication in multiple tumor models. Furthermore, we identified distinct cell populations of responders and non-responders to bintrafusp alfa, with responders showing a shift toward a more immune-permissive microenvironment. The cellular and molecular signatures of responders versus non-responders to combined TGFß and PD-L1 blockade provide important insights into future personalized immunotherapy in SCC.

Combined EGFR1 and PARP1 Inhibition Enhances the Effect of Radiation in Head and Neck Squamous Cell Carcinoma Models.

Head and neck squamous cell carcinoma (HNSCC) is a challenging cancer with little change in five-year overall survival rate of 50-60% over the last two decades. Radiation with or without platinum-based drugs remains the standard of care despite limited benefit and high toxicity. HNSCCs often overexpress epidermal growth factor receptor (EGFR) and inhibition of EGFR signaling enhances radiation sensitivity by interfering with repair of radiation-induced DNA breaks. Poly (adenosine diphosphate-ribose) polymerase-1 (PARP1) also participates in DNA damage repair, but its inhibition provides benefit in cancers that lack DNA repair by homologous recombination (HR) such as BRCA-mutant breast cancer. HNSCCs in contrast are typically BRCA wild-type and proficient in HR repair, making it challenging to apply anti-PARP1 therapy in this model. A recently published study showed that a combination of EGFR and PARP1 inhibition induced more DNA damage and greater growth control than each single agent in HNSCC cells. This led us to hypothesize that a combination of EGFR and PARP1 inhibition would enhance the efficacy of radiation to a greater extent than each single agent, providing a rationale for paradigm-shifting combinatorial approaches to improve the standard of care in HNSCC. Here, we report a proof-of-concept study using Detroit562 HNSCC cells, which are proficient for DNA repair by both HR and non-homologous end joining (NHEJ) mechanisms. We tested the effect of adding cetuximab and/or olaparib (inhibitors of EGFR and PARP1, respectively) to radiation and compared it to that of cisplatin and radiation combination, which is the standard of care. Our results demonstrate that the combination of cetuximab and olaparib with radiation was superior to the combination of any single drug with radiation in terms of induction of unrepaired DNA damage, induction of senescence, apoptosis and clonogenic death, and tumor growth control in mouse xenografts. Combined with our recently published phase I safety data on cetuximab/olaparib/radiation triple combination, the data reported here demonstrate a potential for combining biologically-based therapies that might optimize radiosensitization in HNSCC.

PARP Inhibition Enhances Radiotherapy of SMAD4-Deficient Human Head and Neck Squamous Cell Carcinomas in Experimental Models.

PURPOSE: SMAD4 loss causes genomic instability and the initiation/progression of head and neck squamous cell carcinoma (HNSCC). Here, we study whether SMAD4 loss sensitizes HNSCCs to olaparib (PARP inhibitor) in combination with radiotherapy (RT). EXPERIMENTAL DESIGN: We analyzed HNSCC The Cancer Genome Atlas data for SMAD4 expression in association with FANC/BRCA family gene expression. Human HNSCC cell lines were screened for sensitivity to olaparib. Isogenic HNSCC cell lines were generated to restore or reduce SMAD4 expression and treated with olaparib, radiation, or the combination. HNSCC pretreatment specimens from a phase I trial investigating olaparib were analyzed. RESULTS: SMAD4 levels correlated with levels of FANC/BRCA genes in HNSCC. HNSCC cell lines with SMAD4 homozygous deletion were sensitive to olaparib. In vivo, olaparib or RT monotherapy reduced tumor volumes in SMAD4-mutant but not SMAD4-positive tumors. Olaparib with RT dual therapy sustained tumor volume reduction in SMAD4-deficient (mutant or knockdown) xenografts, which exhibited increased DNA damage and cell death compared with vehicle-treated tumors. In vitro, olaparib alone or in combination with radiation caused lower clonogenic survival, more DNA damage-associated cell death, and less proliferation in SMAD4-deficient cells than in SMAD4-positive (endogenous SMAD4 or transduced SMAD4) cells. Applicable to clinic, 5 out of 6 SMAD4-negative HNSCCs and 4 out of 8 SMAD4-positive HNSCCs responded to a standard treatment plus olaparib in a phase I clinical trial, and SMAD4 protein levels inversely correlated with DNA damage. CONCLUSIONS: SMAD4 levels are causal in determining sensitivity to PARP inhibition in combination with RT in HNSCCs.

Inhibiting Translation Elongation with SVC112 Suppresses Cancer Stem Cells and Inhibits Growth in Head and Neck Squamous Carcinoma.

Cancer stem cells (CSC) drive growth, therapy resistance, and recurrence in head and neck squamous cell carcinoma (HNSCC). Regulation of protein translation is crucial for normal stem cells and CSCs; its inhibition could disrupt stemness properties, but translation inhibitors are limited clinically due to toxicity. SVC112 is a synthetic derivative of bouvardin, a plant-derived translation elongation inhibitor. SVC112 had greater antiproliferative effects on HNSCC cells compared with the FDA-approved translation inhibitor omacetaxine mepesuccinate (HHT). SVC112 preferentially inhibited cancer cells compared with patient-matched cancer-associated fibroblasts, whereas HHT was equally toxic to both. SVC112 reduced sphere formation by cell lines and CSCs. SVC112 alone inhibited the growth of patient-derived xenografts (PDX), and SVC112 combined with radiation resulted in tumor regression in HPV-positive and HPV-negative HNSCC PDXs. Notably, CSC depletion after SVC112 correlated with tumor response. SVC112 preferentially impeded ribosomal processing of mRNAs critical for stress response and decreased CSC-related proteins including Myc and Sox2. SVC112 increased cell-cycle progression delay and slowed DNA repair following radiation, enhancing colony and sphere formation radiation effects. In summary, these data demonstrate that SVC112 suppresses CSC-related proteins, enhances the effects of radiation, and blocks growth of HNSCC PDXs by inhibiting CSCs. SIGNIFICANCE: Inhibiting protein elongation with SVC112 reduces tumor growth in head and neck squamous cell carcinoma and increases the effects of radiation by targeting the cancer stem cell pool.

CXCL14 suppresses human papillomavirus-associated head and neck cancer through antigen-specific CD8+ T-cell responses by upregulating MHC-I expression.

Evasion of the host immune responses is critical for both persistent human papillomavirus (HPV) infection and associated cancer progression. We have previously shown that expression of the homeostatic chemokine CXCL14 is significantly downregulated by the HPV oncoprotein E7 during cancer progression. Restoration of CXCL14 expression in HPV-positive head and neck cancer (HNC) cells dramatically suppresses tumor growth and increases survival through an immune-dependent mechanism in mice. Although CXCL14 recruits natural killer (NK) and T cells to the tumor microenvironment, the mechanism by which CXCL14 mediates tumor suppression through NK and/or T cells remained undefined. Here we report that CD8+ T cells are required for CXCL14-mediated tumor suppression. Using a CD8+ T-cell receptor transgenic model, we show that the CXCL14-mediated antitumor CD8+ T-cell responses require antigen specificity. Interestingly, CXCL14 expression restores major histocompatibility complex class I (MHC-I) expression on HPV-positive HNC cells downregulated by HPV, and knockdown of MHC-I expression in HNC cells results in loss of tumor suppression even with CXCL14 expression. These results suggest that CXCL14 enacts antitumor immunity through restoration of MHC-I expression on tumor cells and promoting antigen-specific CD8+ T-cell responses to suppress HPV-positive HNC.

Radioimmunotherapy for the treatment of head and neck cancer.

Evidence to date shows that immune checkpoint inhibitors have little benefit in most patients with head and neck squamous cell carcinoma (HNSCC). Intense interest is focused on identifying and developing rational combinations of immune checkpoint inhibitors and different therapeutic interventions to enhance response rates and overcome immune checkpoint inhibitor resistance. Combining radiotherapy, a primary HNSCC treatment modality, with immunotherapy has been shown to induce potent antitumour immune responses in many cancers including HNSCC. In addition to its direct cytotoxic effect on the cancer cell, radiotherapy can shape the tumour microenvironment to affect the abundance and composition of tumour-infiltrating immune cells and therefore change responses to immune checkpoint inhibitor therapy. In this Series paper, we examine how radiotherapy can be used to its maximum therapeutic potential in the setting of immunotherapy treatment for HNSCC by focusing on published clinical and preclinical data. We rely on preclinical evidence for this disease to discuss how radiotherapy can help create and maintain an immunologically permissive environment. Our hope is that such mechanistic insights will provide a foundation for maximising the use of radioimmunotherapy in disease control, designing future trials, interpreting emerging immunotherapy data, and accelerating discovery within radioimmunotherapy interventions for HNSCC.

National Cancer Institute (NCI) state of the science: Targeted radiosensitizers in colorectal cancer.

Colorectal cancer (CRC) represents a major public health problem as the second leading cause of cancer-related mortality in the United States. Of an estimated 140,000 newly diagnosed CRC cases in 2018, roughly one-third of these patients will have a primary tumor located in the distal large bowel or rectum. The current standard-of-care approach includes curative-intent surgery, often after preoperative (neoadjuvant) radiotherapy (RT), to increase rates of tumor down-staging, clinical and pathologic response, as well as improving surgical resection quality. However, despite advancements in surgical techniques, as well as sharpened precision of dosimetry offered by contemporary RT delivery platforms, the oncology community continues to face challenges related to disease relapse. Ongoing investigations are aimed at testing novel radiosensitizing agents and treatments that might exploit the systemic antitumor effects of RT using immunotherapies. If successful, these treatments may usher in a new curative paradigm for rectal cancers, such that surgical interventions may be avoided. Importantly, this disease offers an opportunity to correlate matched paired biopsies, radiographic response, and molecular mechanisms of treatment sensitivity and resistance with clinical outcomes. Herein, the authors highlight the available evidence from preclinical models and early-phase studies, with an emphasis on promising developmental therapeutics undergoing prospective validation in larger scale clinical trials. This review by the National Cancer Institute's Radiation Research Program Colorectal Cancer Working Group provides an updated, comprehensive examination of the continuously evolving state of the science regarding radiosensitizer drug development in the curative treatment of CRC.

Pancreatic Tumor Microenvironment Modulation by EphB4-ephrinB2 Inhibition and Radiation Combination.

PURPOSE: A driving factor in pancreatic ductal adenocarcinoma (PDAC) treatment resistance is the tumor microenvironment, which is highly immunosuppressive. One potent immunologic adjuvant is radiotherapy. Radiation, however, has also been shown to induce immunosuppressive factors, which can contribute to tumor progression and formation of fibrotic tumor stroma. To capitalize on the immunogenic effects of radiation and obtain a durable tumor response, radiation must be rationally combined with targeted therapies to mitigate the influx of immunosuppressive cells and fibrosis. One such target is ephrinB2, which is overexpressed in PDAC and correlates negatively with prognosis.Experimental Design: On the basis of previous studies of ephrinB2 ligand-EphB4 receptor signaling, we hypothesized that inhibition of ephrinB2-EphB4 combined with radiation can regulate the microenvironment response postradiation, leading to increased tumor control in PDAC. This hypothesis was explored using both cell lines and in vivo human and mouse tumor models. RESULTS: Our data show this treatment regimen significantly reduces regulatory T-cell, macrophage, and neutrophil infiltration and stromal fibrosis, enhances effector T-cell activation, and decreases tumor growth. Furthermore, our data show that depletion of regulatory T cells in combination with radiation reduces tumor growth and fibrosis. CONCLUSIONS: These are the first findings to suggest that in PDAC, ephrinB2-EphB4 interaction has a profibrotic, protumorigenic role, presenting a novel and promising therapeutic target.

Inhibition of EphB4-Ephrin-B2 Signaling Reprograms the Tumor Immune Microenvironment in Head and Neck Cancers.

Identifying targets present in the tumor microenvironment that contribute to immune evasion has become an important area of research. In this study, we identified EphB4-ephrin-B2 signaling as a regulator of both innate and adaptive components of the immune system. EphB4 belongs to receptor tyrosine kinase family that interacts with ephrin-B2 ligand at sites of cell-cell contact, resulting in bidirectional signaling. We found that EphB4-ephrin-B2 inhibition alone or in combination with radiation (RT) reduced intratumoral regulatory T cells (Tregs) and increased activation of both CD8+ and CD4+Foxp3- T cells compared with the control group in an orthotopic head and neck squamous cell carcinoma (HNSCC) model. We also compared the effect of EphB4-ephrin-B2 inhibition combined with RT with combined anti-PDL1 and RT and observed similar tumor growth suppression, particularly at early time-points. A patient-derived xenograft model showed reduction of tumor-associated M2 macrophages and favored polarization towards an antitumoral M1 phenotype following EphB4-ephrin-B2 inhibition with RT. In vitro, EphB4 signaling inhibition decreased Ki67-expressing Tregs and Treg activation compared with the control group. Overall, our study is the first to implicate the role of EphB4-ephrin-B2 in tumor immune response. Moreover, our findings suggest that EphB4-ephrin-B2 inhibition combined with RT represents a potential alternative for patients with HNSCC and could be particularly beneficial for patients who are ineligible to receive or cannot tolerate anti-PDL1 therapy. SIGNIFICANCE: These findings present EphB4-ephrin-B2 inhibition as an alternative to anti-PDL1 therapeutics that can be used in combination with radiation to induce an effective antitumor immune response in patients with HNSCC.

Statin use associated with improved overall and cancer specific survival in patients with head and neck cancer.

OBJECTIVES: Studies have shown the utility of lipid-lowering agents in improving outcomes in various cancers. We aim to explore how statins affect overall survival and cancer specific survival in head and neck cancer patients using population-based datasets. PATIENTS AND METHODS: Using the Surveillance, Epidemiology, and End Results (SEER)-Medicare linked dataset, we separated HNC patients into three groups: those with no hyperlipidemia (nH), those with hyperlipidemia and not taking a statin (HnS), and those with hyperlipidemia and taking a statin (H + S). Overall survival (OS) and cancer specific survival (CSS) were compared between the three groups based on disease subsite (oral cavity, oropharynx, and other) using Kaplan-Meier and multivariate Cox regression analysis (MVA), controlling for demographic, socioeconomic, staging, treatment, and comorbidity covariates. Using Pearson chi-square analysis, we also compared the incidence of cancer-related toxicity events. RESULTS: There were 495 nH, 567 HnS, and 530 H + S patients. H + S patients had superior OS and CSS (73.0, 81.2%) relative to nH (58.6, 69.1%) and HnS groups (61.7, 69.2%) (p < 0.01). On MVA, H + S patients showed improved OS (p < 0.01) and CSS (p = 0.04) compared to nH (HR = 1.64, 1.56) and HnS (HR = 1.40, 1.37). MVA stratified by subsite yielded similar results for oral cavity and oropharyngeal disease. Toxicity-related events did not differ significantly between the groups. CONCLUSION: HNC patients with hyperlipidemia and taking a statin demonstrated improved outcomes compared to nH and HnS patients, further supporting statins' role as a potential adjuvant anti-neoplastic agent in HNC. Further prospective studies to investigate the impact of statins on HNC outcomes are warranted.

STAT3 Modulation of Regulatory T Cells in Response to Radiation Therapy in Head and Neck Cancer.

BACKGROUND: Radioresistance represents a major problem in the treatment of head and neck cancer (HNC) patients. To improve response, understanding tumor microenvironmental factors that contribute to radiation resistance is important. Regulatory T cells (Tregs) are enriched in numerous cancers and can dampen the response to radiation by creating an immune-inhibitory microenvironment. The purpose of this study was to investigate mechanisms of Treg modulation by radiation in HNC. METHODS: We utilized an orthotopic mouse model of HNC. Anti-CD25 was used for Treg depletion. Image-guided radiation was delivered to a dose of 10 Gy. Flow cytometry was used to analyze abundance and function of intratumoral immune cells. Enzyme-linked immunosorbent assay was performed to assess secreted factors. For immune-modulating therapies, anti-PD-L1, anti-CTLA-4, and STAT3 antisense oligonucleotide (ASO) were used. All statistical tests were two-sided. RESULTS: Treatment with anti-CD25 and radiation led to tumor eradication (57.1%, n = 4 of 7 mice), enhanced T-cell cytotoxicity compared with RT alone (CD4 effector T cells [Teff]: RT group mean = 5.37 [ 0.58] vs RT + αCD25 group mean =10.71 [0.67], P = .005; CD8 Teff: RT group mean = 9.98 [0.81] vs RT + αCD25 group mean =16.88 [2.49], P = .01) and induced tumor antigen-specific memory response (100.0%, n = 4 mice). In contrast, radiation alone or when combined with anti-CTLA4 did not lead to durable tumor control (0.0%, n = 7 mice). STAT3 inhibition in combination with radiation, but not as a single agent, improved tumor growth delay, decreased Tregs, myeloid-derived suppressor cells, and M2 macrophages and enhanced effector T cells and M1 macrophages. Experiments in nude mice inhibited the benefit of STAT3 ASO and radiation. CONCLUSION: We propose that STAT3 inhibition is a viable and potent therapeutic target against Tregs. Our data support the design of clinical trials integrating STAT3 ASO in the standard of care for cancer patients receiving radiation.

Validation of NRG oncology/RTOG-0129 risk groups for HPV-positive and HPV-negative oropharyngeal squamous cell cancer: Implications for risk-based therapeutic intensity trials.

BACKGROUND: Radiation Therapy Oncology Group (RTOG)-0129 recursive partitioning analysis was the basis for risk-based therapeutic intensification trials for oropharyngeal cancer (OPC). To the authors' knowledge, the question of whether RTOG-0129 overall survival (OS) estimates for low-risk, intermediate-risk, and high-risk groups are similar in other data sets or applicable to progression-free survival (PFS) is unknown. Therefore, the authors evaluated whether survival differences between RTOG-0129 risk groups persist at 5 years, are reproducible in an independent clinical trial, and are applicable to PFS, and whether toxicities differ across risk groups. METHODS: Prospective randomized clinical trials were analyzed retrospectively. RTOG-0129 evaluated standard versus accelerated fractionation radiotherapy concurrent with cisplatin. RTOG-0522 compared the combination of cisplatin and accelerated fractionation with or without cetuximab. Patients with OPC with available p16 status and tobacco history were eligible. RESULTS: There was a total of 260 patients and 287 patients, respectively, from RTOG-0129 and RTOG-0522, with median follow-ups for surviving patients of 7.9 years (range, 1.7-9.9 years) and 4.7 years (range, 0.1-7.0 years), respectively. Previous OS differences in RTOG-0129 persisted at 5 years. In RTOG-0522, the 5-year OS rates for the low-risk, intermediate-risk, and high-risk groups were 88.1%, 69.9%, and 45.1%, respectively (P for trend, <.001). The 5-year PFS rates for the same 3 groups were 72.9%, 56.1%, and 42.2%, respectively. In RTOG-0522 among a subgroup of patients considered to be at very good risk (p16-positive disease, smoking history of ≤10 pack-years, and classified with T1-T2 disease with ipsilateral lymph nodes measuring ≤6 cm or T3 disease without contralateral or >6 cm lymph nodes), the 5-year OS and PFS rates were 93.8% and 82.2%, respectively. Overall rates of acute and late toxicities were similar by risk group. CONCLUSIONS: RTOG-0129 risk groups persisted at 5 years and were reproducible in RTOG-0522. However, there was variability in the estimates. These data underscore the importance of long-term follow-up and appropriate patient selection in therapeutic deintensification trials.