Comparative Analysis of Tumor Microbiome, Molecular Profile and Immune Cell Abundance by HPV Status in Head and Neck Cancers and Their Impact on Survival

PURPOSE/OBJECTIVE(S)

Traditional clinical and molecular prognostic factors offer valuable insight into the heterogeneous natural history and treatment response of head and neck squamous cell carcinoma (HNSCC) yet fail to explain the full spectrum of observed variability. The tumor microenvironment (TME), comprising microbiome and immune cells can impact treatment response and prognosis. We analyzed The Cancer Genome Atlas (TCGA) to evaluate the association of specific microbes and genes in TME with survival and their differential expression in HPV positive (+) and HPV negative (-) HNSCC.

MATERIALS/METHODS

HNSCC RNA sequencing (RNAseq) samples from TCGA were processed through the Exogenous sequencing in Tumors and Immune Cells (ExoTIC) pipeline to identify gene expression and microbial presence. HPV status was assessed by detection of papillomaviridae family of microbes. Clinical data from TCGA was extracted to compare overall survival (OS) and control for competing variables using Cox proportional hazards regression. Difference in immune cell abundance was evaluated by Kruskal-Wallis test. All statistical analysis was performed using R.

RESULTS

A total of 498 RNAseq samples from TCGA were analyzed. Oral cavity, oropharynx, hypopharynx, and larynx tumors comprised 21.6%, 15%, 1.8%, and 22.2% of specimens, respectively. HPV was detected in 111 patients (22%), most commonly Alpha papillomavirus 9 (90.1%). Of the 5838 enriched microbes, 330 were significantly associated with OS after controlling for tumor stage, smoking, and age. Specifically, the presence of Alpha papillomavirus 9 was associated with significantly improved OS [adjusted HR = 0.60 (95% CI 0.40 - 0.89, p = 0.01)]. Microbial species found in more abundance in HPV- tumors included Citrobacter farmeri, Thermoanaerobacter kivui and Yersinia pestis which are gram negative anaerobes. Genes related to cellular transport and DNA repair were enriched while genes related to proliferation (e.g., SAGE1) were depleted in HPV+ samples. HPV- tumors had a significantly higher number of M0 (p < 0.001) and M2 macrophages (p = 0.035) while HPV+ tumors had more T regulatory cells (p < 0.001) and CD8+ T-cells (p < 0.001).

CONCLUSION

Tumor microenvironment was significantly associated with survival for HNSCC patients, with particular microbes such as Alpha papillomavirus 9 correlating with improved OS. Greater abundance of certain anaerobic microbes was seen in HPV- tumors. These findings suggest TME can be used to predict patient outcomes and potentially guide personalized treatment approaches. We found an abundance of M0 and M2 macrophages in HPV- tumors, which are considered pro-tumorigenic, while anti-tumor M1 macrophages were similar in the two groups. This may help identify mechanism of resistance to immunotherapies and tailor novel immunotherapy combinations in specific patient subgroups. With further prospective research and external validation these findings have the potential to significantly impact the way we treat HNSCC in the future.

Scalp Volumetric Modulated Arc Therapy Using 3D Milled Bolus: Dosimetry, Toxicity and Outcome

PURPOSE/OBJECTIVE(S)

Radiotherapy for scalp lesions is frequently challenging due to the competing needs for target volume coverage, sparing of numerous critical nearby OARs, and reproducible bolus setup despite the irregular and highly convex scalp geometry. Here, we evaluate the use of 3D milled bolus in treating such tumors.

MATERIALS/METHODS

A retrospective analysis of scalp patients (pts) treated between 2016-2022 using 3D milled bolus and VMAT. All pts were treated with 6 MV photon beams, IGRT via daily CBCT, and 6-degree of Freedom (6-DOF) couch tops. Pts demographics, tumor characteristics, DVHs, toxicities and outcomes were evaluated. Regional control (RC) defined as control of the disease in the rest of the scalp/neck and local control (LC) defined as disease control within the PTV.

RESULTS

A total of 23 pts were identified. Median age 74 (46-85), ECOG performance status was 0-1 in 20 pts (87%) and 92% were males. The histopathologies were squamous cell carcinoma (SCC) (61%), angiosarcoma (AS) (35%) and melanoma (4%). 35% of pts were treated with definitive intent to gross disease; the remaining 65% were treated post-operatively, 22% with microscopically positive margins and 43% with negative margins. 21% had perineural invasion (PNI), and none had lymphovascular invasion (LVI). 78% had T3/T4 and 13% had N+ disease. Median radiation dose was 66 Gy (60-69.96Gy). 44% received concurrent systemic therapy (Paclitaxel 22%, Cemiplimab 12%, Temozolomide 5%, Nivolumab 5%). In 40% of pts, the whole scalp was treated; in the remaining 60%, the median ratio of PTV volume to scalp volume was 35% (25-90%). 22% of pts (n = 5) had neck irradiation for prophylactic (3pts)/ neck lymph node involvement (2 pts). The median brain Dmax was 65 Gy (52.5-71.9), median brain mean dose was 15.4Gy (1.4-38.4), median eye Dmax was 10.9Gy (0.23-49), median cochlea mean was 8.4Gy (0.1-20.4), median lacrimal gland mean dose was 6.8Gy (0.11-38), median hippocampus Dmin was 5.9Gy (0.1-14.9) and Dmax was 10Gy (0.3-23). Most common acute side effects were grade 1-2 fatigue (100%), grade 1-2 pain (78%), grade 1 dysgeusia (22%), grade 1-2 dermatitis (74%). The only grade > = 3 adverse event was grade 3 dermatitis in 26%. Regarding long-term side effects, one pt had grade 2 osteoradionecrosis and other one developed grade 2 skin ulcer. 17% developed grade 1 memory impairment. 17% had grade 1 eye dryness. None developed brain radionecrosis. At a median follow-up was 14.4 months (1-73.5), the 1-yr LC was 96%. The 1-yr RC was 75% overall, 100% in angiosarcoma vs 62% in SCC (p = 0.18). Of the 4 regional recurrences, 1 pt had marginal recurrence along V1, 2 had neck nodal recurrence, and 1 had recurrence elsewhere in the scalp. 1-yr DMFS was 62% overall. 1-yr OS was 78% overall, 100% for AS vs 64% for SCC (P = 0.097).

CONCLUSION

VMAT planning with 3D milled bolus permits technically sound radiotherapy for scalp targets with an acceptable toxicity profile and relatively favorable clinical outcomes. This approach warrants further evaluation in a larger prospective study.

Brachial Plexus Tolerance to Standard Fractionation Re-Irradiation: The Ohio State University Experience

PURPOSE/OBJECTIVE(S)

Factors contributing to brachial plexopathy (BPP) in the re-irradiation setting need further assessment. Preliminary work revealed that higher the doses and the use of concurrent cisplatin were associated with higher risk of BPP. Here, we expand our cohort and increase our follow-up duration, given the late nature of BPP development.

MATERIALS/METHODS

Sixty-two BP sites with 41 patients (pts), treated between 2015 and 2020 for recurrent H&N cancer, were assessed. Contours and plans were reviewed via a prospective multidisciplinary chart rounds prior to treatment delivery and re-verified by two authors prior to this analysis. Kaplan-Meier and logistic regression were used to test the correlation between variables and outcomes. ROC was used to evaluate the cutoff values. Common terminology criteria of adverse events were used to define BPP.

RESULTS

The median age of pts was 63 (29-78) and 65% were males. Median prescription dose was 70 Gy (60-70) for the 1st course and 66 Gy (44-70) for the 2nd course. 13% received intraoperative radiotherapy (IORT) during salvage treatment ranging from 10-15 Gy. 30% of pts in the 1st course and 80% in the 2nd course of pts had surgery. Concurrent chemotherapy was delivered to 71% of pts in the 1st course (Cisplatin 34%, Cetuximab 22%, Carboplatin +/- Paclitaxel 15%) and 76% in the 2nd course (Carboplatin/Paclitaxel 41%, Cisplatin 19%, Cetuximab 12%, Nivolumab 4%). The median interval between courses was 26.5 months (8-221). The median cumulative Dmax (0.03cc) and mean dose to the BP were 96.5 Gy (51-144) and 61.5 Gy (15-110), respectively. The median V60, V70, V80, V90, and V100 were 3.6cc (0.03-10.4), 2.4cc (0-9.9), 1.3cc (0-9.3), 0.6cc (0-8.4), and 0.0015cc (0-7.2), respectively. The median follow-up after the completion of the 2nd RT course was 19 months (1.4-71.5). The 1-yr incidence of BPP was 17%, with a median time to onset of 8.9 months (1-16.6). Factors associated with development of BPP were cumulative Dmax > 100 Gy (HR 1.06, [CI 1.014-1.1], p = 0.009), cumulative mean dose >70 Gy (HR 1.05, [CI 1.01-1.09], p = 0.03), V80 > 1.6cc (HR 1.2. [CI 0.99- 1.52], p = 0.06), V90 > 1cc (HR 1.3, [CI 1.013-1.58], p = 0.038), V100 > 0.3cc (HR 1.33, [1.044-1.69], p = 0.021) and the usage of concurrent cisplatin during the 2nd course (HR 8.9, [CI 2.36-33.75], p = 0.001). Other factors including gender, age, surgery, treatment interval between the two courses, IORT, V60, and V70 were not associated with increased risk of BPP. The incidence of grade 1, grade 2, and grade 3 BPP were 9.6%, 3% and 2.4%, respectively. The 1-yr OS was 70% and LC was 60%.

CONCLUSION

At a median follow up of 19 months, the 1-yr incidence of grade 2 and 3 BPP was approximately 5%. Cisplatin during the 2nd course, cumulative metrics of Dmax 100 Gy, mean 70 Gy, V80 1.6cc, V90 1cc and V100 0.3cc were associated with development of BPP. Prospective study, longer follow up, and higher numbers are warranted. To our knowledge, this represents the largest cohort and longest follow up yet reported for BPP in the re-irradiation setting.

Toxicity and Outcomes of Definitive Local Therapy in Elderly Patients with HPV-Associated Oropharyngeal Cancer

PURPOSE/OBJECTIVE(S)

The incidence of human papillomavirus (HPV) associated oropharyngeal squamous cell carcinoma (HPV-OPSCC) has increased in elderly patients. It is unclear if survival outcomes in elderly patients are similar to those seen in younger patients with HPV-OPSCC. In this study we evaluated disease outcomes and toxicity in an elderly HPV-OPSCC population treated with curative-intent treatment of radiotherapy with or without chemotherapy.

MATERIALS/METHODS

We performed a retrospective study of elderly patients (≥70 years old) with HPV-OPSCC treated between 2011-2021 with radiation therapy (RT) with or without chemotherapy. Time to event analysis for overall survival (OS), local control, and progression free survival (PFS) were estimated using the Kaplan-Meier method. Univariate and multivariate Cox regression models were used to estimate the hazard ratio associated with the covariates.

RESULTS

We identified 77 elderly HPV-OPSCC patients, of which 60 (78%) were treated with concurrent chemotherapy. Twenty (26%) received concurrent Carboplatin and Taxol, 16 (21%) received Cetuximab, 14 (18%) received Cisplatin,7 (9%) received Carboplatin alone, and 2 (2%) received immunotherapy (Pembrolizumab or Nivolumab). The majority of patients received a radiation dose of 69.96 Gy or 70 Gy (89%). Forty-seven patients (61%) were stage I, 11 (14%) were stage II, 16 (21%) were Stage III, and 3 (4%) had stage IV disease. 50 patients (64%) were former smokers, 27 (35%) were nonsmokers and 1 (1%) is a current smoker. 37 patients (48%) had a ≥10 pack year smoking history. The 5-year OS, LC, and PFS for the entire cohort was 61%, 94%, and 58%, respectively. On univariate analysis, ECOG performance status (HR 0.22, [CI 0.06-0.78], p = 0.019) and Charlson Comorbidity Index (CCI) (HR 1.33, [CI 1.06-1.69], p = 0.014) were significant predictors of OS. On multivariate analysis, only CCI (HR 1.34, [CI 1.02-1.77], p = 0.035) was a significant predictor of OS. The rate of long-term feeding tube dependency was 9%. Late toxicities include osteoradionecrosis in 4 patients (5%), aspiration in 3 patients (4%), and esophageal stricture in 2 patients (3%).

CONCLUSION

Elderly HPV-OPSCC patients treated with definitive intent radiotherapy with or without chemotherapy have favorable disease outcomes with low rates of late toxicity. The Charlson-Comorbidity Index can identify a subset of patients who may have a prolonged OS, and therefore may benefit from more aggressive treatment.