e14710 Background: Lung cancer affects a disproportional number of socioeconomically disadvantaged patients (pts). Responses to checkpoint inhibitor therapy (CIT) vary. Microbiome diversity may correlate with benefit from CIT. High fiber diets lead to microbiome diversity. We hypothesize that unexplained lung cancer disparities may be in part due to differences in microbiome diversity determined by unhealthy dietary patterns dictated by lower SES. Methods: Following IRB review, 25 pts with metastatic NSCLC starting CIT-based treatment were enrolled. Pre-treatment oral and fecal samples were collected. 24-hour dietary recalls were obtained. SES index was calculated based on education, employment, housing and annual income. High fiber intake was defined as > 20 g/day. Best treatment response per RECIST 1.1 was assessed. Microbial 16s rRNA were sequenced with Illumina MiSeq platform. Sequence analyses utilized QIIME 2 with DADA2 plugin. Taxonomic assignments used the Greengenes database. Microbiome composition was analyzed by calculating alpha diversity (Chao1, Shannon diversity and Simpson index), beta diversity and differential abundance of microbial compositions. Hierarchical linear model was constructed for each SES variable with and without biological covariates. Results: Pts with samples >1000 operational taxonomic unit (OTU) levels were included (N = 22) in the analysis. 50% were male, median age was 71, 36% (8/22) were of Black race and 23% (5/22) were of low SES. Median fiber intake was 11.9 grams. Males had higher alpha diversity than females (p=.038). Pts with high fiber intake had greater fecal Proteobacteria compared to low fiber intake pts (p<0.05). Bacteroides and Firmicutes fecal levels were significantly different for all pts compared to Human Microbiome Project (HMP) reported normal levels (p<0.01). Actinobacteria and Proteobacteria levels for low-fiber intake pts were also significantly elevated compared to HMP normal levels (p<0.05). There were no differences observed in microbiome when comparing SES index. However, high SES index patients had elevated fecal levels of Actinobacteria, Firmicutes and Proteobacteria and lower levels of Bacteroides compared to HMP levels. There was a trend towards higher alpha diversity of oral samples in partial responders pts compared to those with stable or progression of the disease (p=0.08). Conclusions: Pts with metastatic NSCLC exhibited different microbial composition compared to HMP normal levels. Associations between SES and microbial distribution in such pts warrant further investigation. Increased sample size is needed to better determine differences in oral microbiome in responders to immunotherapy and better evaluate the role of sex in this setting.

Introduction: Because limited data exist, we sought to evaluate timeliness of multimodal treatments in a safety net breast cancer population. Methods: Breast cancer patients treated at a safety net hospital from 2016 to 2020 were analyzed retrospectively. Time intervals were defined as primary time (PT) from diagnosis to initiation of primary intervention, secondary time (ST) from completion of primary to initiation of secondary intervention, and tertiary time (TT) from completion of secondary to initiation of tertiary intervention. Variables included primary language, insurance type, and race. Results: Of 223 patients, 99 (44.4%) primarily spoke Spanish, 29 (13.0%) were of Black race, and 184 (82.5%) had Medicaid or uninsured status. Median (IQR) age at diagnosis was 55 (4862) years. Primary intervention was surgical in 127/216 (58.8%); secondary intervention was systemic in 38/169 (22.5%); and tertiary intervention was radiation in 67/80 (83.8%). Overall, median days (IQR) for PT were 69 (53, 98), ST were 65 (42, 95), and TT were 69 (43, 88). PT was significantly longer in Black [105 (76, 142) days] patients compared to non-Hispanic White patients [68 (51, 107) days, P = 0.031)] and White Hispanic patients [65 (53,91) days, P = 0.014]. There were no significant differences in PT, ST, or TT by spoken language or insurance type. Conclusions: Black patients remain at risk due to prolonged time to intervention. Spanishspeaking status was not associated with inferior timeliness or completion of multimodal care at a safety net hospital. Identifying safety net hospital barriers to achieving benchmarks for timely completion of all phases of multimodal care warrants further attention. & COPY; 2023 Elsevier Inc. All rights reserved.

Objectives: To identify predictors of overall survival (OS) in oropharyngeal squamous cell carcinoma (OPSCC) patients who achieved complete response (CR). Methods: We performed a retrospective study of OPSCC patients who achieved CR from a single academic medical center. Associations between OS, AJCC 8th edition staging system, definitive treatment choice, smoking history, and p16 status were assessed. Results: p16+ status was associated with favorable prognosis for CR (p < 0.001) but not non-CR (p = 0.67) patients. For early stage, p16+ OPSCC patients who achieved CR, surgery + adjuvant radiation (RT) treatment was more durable compared to concurrent chemoradiation (CRT), particularly in smokers. Conclusions: Curative intent treatment choice and smoking history has an impact on the long-term OS of the CR p16+ OPSCC cohort. Prospective studies to define the optimal multi-modality treatment option to manage p16+ OPSCC patients is needed.

Abstract Background The incidence of p16+ oropharyngeal squamous cell carcinoma (OPSCC) has been increasing. The notion that p16+ OPSCC has a propensity for atypical and disseminating metastasis has gained traction. We compared treatment failure patterns in p16+ and p16− OPSCC and evaluated survival impact. Methods Retrospective analysis of patients with recurrent/metastatic OPSCC disease between 1/2009 and 12/2019. Results Thirty‐eight p16+ and 36 p16− patients were identified. Three distinct failure patterns (distant vs. locoregional, atypical vs. typical, and disseminating vs. non‐disseminating) were studied. No significant differences were found between p16+ and p16− patients. Multivariate analysis showed p16 status was an independent prognostic biomarker; p16+ patients have a favorable overall survival compared to p16− patients (HR 0.34, 95% CI 0.16–0.77; P = .005). Conclusions We challenge the view that p16+ OPSCC exhibits a distinctive treatment failure pattern and showed that p16 status impacts patient survival independent of disease progression.

In head and neck squamous cell carcinoma (HNSCC), anti-PD-1 inhibitors are approved for recurrent/metastatic (R/M) disease and anticipated to expand to other indications. The impact of p16 status and anatomical site on overall survival (OS) in immunotherapy-treated HNSCC patients remains unresolved. We performed a retrospective analysis of R/M HNSCC patients receiving anti-PD-1 immunotherapy at our academic medical center with an extensive community satellite network. Fifty-three R/M HNSCC patients were treated with anti-PD-1 immunotherapy and had a median OS of 6 months. Anatomical site was associated with distinct OS; oropharynx and larynx patients have superior OS compared to oral cavity patients. Analysis of the OPSCC subset showed p16+ status as a favorable, independent prognostic biomarker (HR 7.67 (1.23–47.8); p = 0.029). Further studies to assess the link between anatomical site, p16 status, and anti-PD-1 treatment outcomes in large cohorts of R/M HNSCC patients managed in real-world clinical practices and clinical trials should be prioritized.

PURPOSE: Human papilloma virus-positive (HPV+) oropharyngeal squamous cell carcinoma (OPSCC), diagnosed with p16 immunohistochemistry, is associated with favorable prognosis; however, this connection was established using European American (EA)-skewed populations. The impact of p16/human papillomavirus status on outcomes in African American (AA) OPSCC patients remains to be settled. In this study, we determine the association between cancer disparity and p16 status in an OPSCC cohort controlling for time to treatment initiation (TTI), a surrogate for medical care access. MATERIALS AND METHODS: We analyzed data from all patients diagnosed with OPSCC (N = 440) between 2010 and 2017, who received treatment at our academic medical center. Associations between age, disease stage, sex, p16 status, race, TTI, and overall survival (OS) were investigated. RESULTS: TTI was similar between AA and EA OPSCC patients in our p16+ (P = .291) or p16- (P = .715) cohorts. Among p16+ OPSCC patients, the median OS was > 8.65 years for EA patients compared with 5.038 years (95% CI, 2.019 to 5.30; P = .003, log-rank) for AA patients. For p16- patients, the median OS was 5.74 years (95% CI, 3.32 to 6.99) for EA patients and 1.85 years (95% CI, 0.978 to 4.50; P = .03, log-rank) for AA patients. Multivariate Cox regression analysis showed that race was an independent prognostic biomarker and the most impactful co-variate for OS (hazard ratio, 0.40; 95% CI, 0.00 to 0.69; P = .001). CONCLUSION: Our work showed that AAs with p16+ OPSCC have surprisingly poor clinical outcomes and are thus poor candidates for treatment de-escalation regimens. Caution should be exercised when extending clinical guidelines based on EA-majority studies to non-EA populations.