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High-dose (HD) cisplatin remains the standard of care with chemoradiation for locally advanced oropharyngeal cancer (OPC). Cooperative group trials mandate bolus-HD (100 mg/m2 × 1 day, every 3 weeks) cisplatin administration at the beginning of the week to optimize radiosensitization-a requirement which may be unnecessary. This analysis evaluates the impact of chemotherapy administration day of week (DOW) on outcomes. We also report our institutional experience with an alternate dosing schedule, split-HD (50 mg/m2 × 2 days, every 3 weeks). We retrospectively reviewed 435 definitive chemoradiation OPC patients from 10 December 2001 to 23 December 2014. Those receiving non-HD cisplatin regimens or induction chemotherapy were excluded. Data collected included DOW, dosing schedule (bolus-HD vs split-HD), smoking, total cumulative dose (TCD), stage, Karnofsky Performance Status, human papillomavirus status and creatinine (baseline, peak and posttreatment baseline). Local failure (LF), regional failure (RF), locoregional failure (LRF), distant metastasis (DM), any failure (AF, either LRF or DM) and overall survival (OS) were calculated from radiation therapy start. Median follow-up was 8.0 years (1.8 months-17.0 years). DOW, dosing schedule and TCD were not associated with any outcomes in univariable or multivariable regression models. There was no statistically significant difference in creatinine or association with TCD in split-HD vs bolus-HD. There was no statistically significant association between DOW and outcomes, suggesting that cisplatin could be administered any day. Split-HD had no observed differences in outcomes, renal toxicity or TCD compared to bolus-HD cisplatin. Our data suggest that there is some flexibility of when and how to give HD cisplatin compared to clinical trial mandates.

Because of the national emergency triggered by the coronavirus disease 2019 (COVID‐19) pandemic, government‐mandated public health directives have drastically changed not only social norms but also the practice of oncologic medicine. Timely head and neck cancer (HNC) treatment must be prioritized, even during emergencies. Because severe acute respiratory syndrome coronavirus 2 predominantly resides in the sinonasal/oral/oropharyngeal tracts, nonessential mucosal procedures are restricted, and HNCs are being triaged toward nonsurgical treatments when cures are comparable. Consequently, radiation utilization will likely increase during this pandemic. Even in radiation oncology, standard in‐person and endoscopic evaluations are being restrained to limit exposure risks and preserve personal protective equipment for other frontline workers. The authors have implemented telemedicine and multidisciplinary conferences to continue to offer standard‐of‐care HNC treatments during this uniquely challenging time. Because of the lack of feasibility data on telemedicine for HNC, they report their early experience at a high‐volume cancer center at the domestic epicenter of the COVID‐19 crisis., Cancer care is undeniably affected by the coronavirus disease 2019 (COVID‐19) public health emergency, but quality cancer care must persist. A high‐volume cancer center from the domestic epicenter of the COVID‐19 crisis shares its multidisciplinary approach to integrating current public health restrictions and adopting telemedicine to optimize the care of patients with head and neck cancer; it is hoped that this center's experience will provide helpful insights to oncology colleagues.

Objectives Patients with prior irradiated head and neck cancer (HNC) who are ineligible for definitive retreatment have limited local palliative options. We report the largest series of the use of the Quad Shot (QS) regimen as a last-line local palliative therapy. Materials and Methods We identified 166 patients with prior HN radiation therapy (RT) treated with QS regimen (3.7 Gy twice daily over 2 consecutive days at 4 weeks intervals per cycle, up to 4 cycles). Palliative response defined by symptom(s) relief or radiographic tumor reduction, locoregional progression free survival (LPFS), overall survival (OS) and radiation-related toxicity were assessed. Results Median age was 66 years. Median follow-up for all patients was 6.0 months and 9.7 months for living patients. Overall palliative response rate was 66% and symptoms improved in 60% of all patients. Predictors of palliative response were > 2 year interval from prior RT and 3–4 QS cycles. Median LPFS was 5.1 months with 1-year LPFS 17.7%, and median OS was 6.4 months with 1-year OS 25.3%. On multivariate analysis, proton RT, KPS > 70, presence of palliative response and 3–4 QS cycles were associated with improved LPFS and improved OS. The overall Grade 3 toxicity rate was 10.8% (n = 18). No Grade 4–5 toxicities were observed. Conclusion Palliative QS is an effective last-line local therapy with minimal toxicity in patients with previously irradiated HNC. The administration of 3–4 QS cycles predicts palliative response, improved PFS, and improved OS. KPS > 70 and proton therapy are associated with survival improvements.

Key Points Question Is intensity-modulated proton therapy (IMPT) associated with fewer treatment-related adverse events and comparable oncologic outcomes for patients with nonmetastatic nasopharyngeal carcinoma (NPC) compared with patients treated with intensity-modulated radiation therapy (IMRT)? Findings In this cohort study of 77 patients with nonmetastatic NPC treated with curative-intent radiotherapy, IMPT treatment was associated with significantly fewer acute adverse events compared with standard-of-care IMRT, with rare late complications. Propensity score–matched analysis demonstrated equally excellent oncologic outcomes in both groups, including 100% locoregional control rate at 2 years in the IMPT group. Meaning These findings suggest that IMPT should be discussed with patients as the potential primary radiotherapy modality for nonmetastatic NPC when it is available because it was associated with less acute toxicity burden compared with IMRT, with potential oncologic benefit in locoregional control., This cohort study compares toxic effects and oncologic outcomes among patients with newly diagnosed nonmetastatic nasopharyngeal carcinoma (NPC) when treated with intensity-modulated proton therapy (IMPT) vs intensity-modulated radiation therapy (IMRT) with or without chemotherapy., Importance Patients with nonmetastatic nasopharyngeal carcinoma (NPC) are primarily treated by radiotherapy with curative intent with or without chemotherapy and often experience substantial treatment-related toxic effects even with modern radiation techniques, such as intensity-modulated radiation therapy (IMRT). Intensity-modulated proton therapy (IMPT) may improve the toxicity profile; however, there is a paucity of data given the limited availability of IMPT in regions with endemic NPC. Objective To compare toxic effects and oncologic outcomes among patients with newly diagnosed nonmetastatic NPC when treated with IMPT vs IMRT with or without chemotherapy. Design, Setting, and Participants This retrospective cohort study included 77 patients with newly diagnosed nonmetastatic NPC who received curative-intent radiotherapy with IMPT or IMRT at a tertiary academic cancer center from January 1, 2016, to December 31, 2019. Forty-eight patients with Epstein-Barr virus (EBV)–positive tumors were included in a 1:1 propensity score–matched analysis for survival outcomes. The end of the follow-up period was March 31, 2021. Exposures IMPT vs IMRT with or without chemotherapy. Main Outcomes and Measures The main outcomes were the incidence of acute and chronic treatment-related adverse events (AEs) and oncologic outcomes, including locoregional failure-free survival (LRFS), progression-free survival (PFS), and overall survival (OS). Results We identified 77 patients (25 [32.5%] women; 52 [67.5%] men; median [interquartile range] age, 48.7 [42.2-60.3] years), among whom 28 (36.4%) were treated with IMPT and 49 (63.6%) were treated with IMRT. Median (interquartile range) follow-up was 30.3 (17.9-41.5) months. On multivariable logistic regression analyses, IMPT was associated with lower likelihood of developing grade 2 or higher acute AEs compared with IMRT (odds ratio [OR], 0.15; 95% CI, 0.03-0.60; P = .01). Only 1 case (3.8%) of a chronic grade 3 or higher AE occurred in the IMPT group compared with 8 cases (16.3%) in the IMRT group (OR, 0.21; 95% CI, 0.01-1.21; P = .15). Propensity score matching generated a balanced cohort of 48 patients (24 IMPT vs 24 IMRT) and found similar PFS in the IMPT and IMRT groups (2-year PFS, 95.7% [95% CI, 87.7%-100%] vs 76.7% [95% CI, 60.7%-97.0%]; hazard ratio [HR], 0.31; 95% CI, 0.07-1.47; P = .14). No locoregional recurrence or death was observed in the IMPT group from the matched cohort. Two-year LRFS was 100% (95% CI, 100%-100%) in the IMPT group and 86.2% (95% CI, 72.8%-100%) in the IMRT group (P = .08). Three-year OS was 100% (95% CI, 100%-100%) in the IMPT group and 94.1% (95% CI, 83.6%-100%) in the IMRT group (P = .42). Smoking history was the only clinical factor significantly associated with both poor LRFS (HR, 63.37; 95% CI, 3.25-1236.13; P = .006) and poor PFS (HR, 6.33; 95% CI, 1.16-34.57; P = .03) on multivariable analyses. Conclusions and Relevance In this study, curative-intent radiotherapy with IMPT for nonmetastatic NPC was associated with significantly reduced acute toxicity burden in comparison with IMRT, with rare late complications and excellent oncologic outcomes, including 100% locoregional control at 2 years. Prospective trials are warranted to direct the optimal patient selection for IMPT as the primary radiotherapy modality for nonmetastatic NPC.

6019 Background: Our previously published proof-of-concept trial using functional imaging to select patient with human papillomavirus (HPV) oropharyngeal carcinoma (OPC) for radiation de-escalation showed promising results. Here we report the outcome of a larger validation trial using the same paradigm where select HPV+ OPC patients received a definitive dose of 30Gy concurrently with chemotherapy and were subsequently observed. Methods: The trial enrolled patients who had p16+, T0-2, N1-N2c, M0 OPC by AJCC 7th TNM. Patients were required to have resection of the primary site (negative margin not required) or core biopsy of lymph node if unknown primary. In addition to standard positron emission tomography (PET), a pre-radiation dynamic 18F-FMISO (fluoromisonidazole) PET was performed to identify hypoxia in gross nodal disease. Patients with evidence of hypoxia ( > 1.2 tumor to muscle standard uptake value on 18F-FMISO) underwent repeat18F-FMISO PET around 2 weeks into radiation. Patients without pre-radiation hypoxia or with resolution of hypoxia on 18F-FMISO PET received 30Gy with 2 cycles of concurrent chemotherapy (cisplatin 100mg/m2 or carboplatin AUC 1.25 x 4 with 5-fluorouracil 2400 mg/m2). Results: From 11/2/17-1/4/21, 158 HPV+ OPC patients consented and were enrolled on trial. Patient characteristics were as follows: male (90%); ages 36-80 years; T-stage T0(26), T1(77), T2(55); N stage N1(19), N2a(15), N2b(95), N2c(29). Of the 114 patients with pre-treatment hypoxia, 24 had persistent hypoxia and received 70Gy. 128 patients were de-escalated to 30Gy and chemotherapy (86% cisplatin). 6 patients withdrew from trial [3 decided to receive standard of care; 3 refused 18F-FMISO PET]. Acute mucositis rates were 11% grade 0, 59% grade 1, and 30% grade 2, respectively. Acute xerostomia rates were 92% grade 1 and 8% grade 2, respectively. Weight loss was infrequent and only 19% complained of grade 1 and 5% complained of grade 2 weight loss. Six patients experienced grade 3 adverse events (diarrhea (2), syncope (2), vasovagal (1), dysphagia (1)). No patients required PEG tubes. With a median follow-up is 12 months (range: 2 months to 40 months), the 1-year locoregional control, distant metastasis-free overall survival rates were 94%, 100%, and 100%, respectively. Among the 30Gy de-escalated patients, none failed in the primary site. 8 patients had recurrent nodal disease underwent successful salvage surgery of which no additional therapy was given to 4 patients. Conclusions: Major de-escalation to 30Gy using patient specific treatment response based on hypoxia resolution resulted in excellent locoregional control with significant toxicity reduction. Updated results along with detailed correlative analysis will be presented. Clinical trial information: NCT03323463.

6541 Background: Despite overexpression of EGFR in HNSCC, cetuximab monotherapy has limited benefit. Fibroblast growth factor receptor (FGFR) signaling is a known resistance mechanism to EGFR inhibition. Lenvatinib is a multi-targeted receptor tyrosine kinase inhibitor (RTKI) and has unique activity against FGFR 1,2,3, and 4. We are evaluating inhibition of EGFR and RTKs including FGFR through the combination of cetuximab and lenvatinib in patients (pts) with R/M HNSCC. Methods: In this phase I/Ib, single-institution study, pts with measurable disease per RECIST v1.1 that is incurable with surgery and radiation are eligible regardless of prior cetuximab therapy. The dose de-escalation phase included pts with HNSCC and cutaneous squamous cell carcinoma (cSCC) treated with standard cetuximab dosing and lenvatinib in 3 potential dose levels (DL): (0) 24mg, (-1) 20mg, (-2) 14mg oral daily in a standard 3+3 design. The primary objective was to determine the MTD of lenvatinib in combination with cetuximab. The expansion phase included an additional 5 pts with HNSCC treated at the MTD. Exploratory endpoints include ORR and PFS in HNSCC pts treated at the MTD. Results: 12 evaluable pts were treated on the dose de-escalation phase. There were no DLTs on DL 0; however, 3/6 pts were removed immediately following the 28-day DLT period due to toxicity that included extensive thrombotic events and athlerosclerotic disease. On DL -1, 0/6 pts (5 HNSCC/1 cSCC) had a DLT establishing lenvatinib 20mg daily as the MTD. 7 pts were enrolled onto the expansion phase; 4 are currently evaluable for response and 2 are unevaluable because of withdrawal due to a cetuximab reaction and required surgery. Of the 9 evaluable HNSCC pts treated with lenvatinib 20mg daily, 6 pts had a PR with a 67% ORR. For the 8 pts who have completed treatment, the median PFS is 3.6 months (range 1.6-10.4). Grade 3 AEs regardless of attribution included hypertension (3), oral mucositis (3) and oral cavity fistula (1). The most common AEs were acneiform rash (7), fatigue (6), and hypertension/hypothyroidism/oral mucositis (5 each). Conclusions: The MTD of lenvatinib 20mg daily with cetuximab appears to be active in R/M HSNCC with an impressive preliminary ORR, warranting further evaluation of the efficacy of this combination. Clinical trial information: NCT03524326 .

6587 Background: Immune checkpoint blockade (ICB) has limited efficacy for radioiodine-refractory thyroid cancer. The high incidence of autoimmune thyroid disease and ICB-induced hypothyroidism suggests that loss of T cell tolerance to thyroid protein epitopes is common and can be activated by ICB to induce immune responses. We hypothesize that RAI can enhance presentation of thyroid protein immunogens and putative neoantigens in thyroid cancers to amplify the effectiveness of ICB. We studied the safety and efficacy of RAI plus the anti-PD-L1 agent durvalumab (durva) in recurrent/metastatic (R/M) patients (pts). Methods: Pts. had at least one RAI-avid tumor on the most recent RAI scan or one tumor on FDG PET with an SUVmax < 10. RECIST measurable disease was required. Any number of prior therapies was allowed. Pts were treated with durva 1500 mg IV every 4 weeks with recombinant human TSH (rhTSH)-stimulated RAI (100 mCi) administered in Cycle 1. Treatment beyond progression was allowed. The primary objective was to assess safety. Durva related dose limiting toxicities (DLTs) were monitored for 6 weeks after the first dose. Since no durva DLTs were observed in the first 6 pts, per protocol rules the trial accrued 11 pts total. Secondary objectives were assessing best overall response (BOR) per RECIST and progression-free survival (PFS). Results: 11 pts (7 female) were enrolled. Eight had prior drug therapy. No DLTs or > Grade 3 durva related adverse events (AEs) were observed. The most common non-laboratory AEs (regardless of attribution) were cough (7), hypertension (7), pain (6), edema (5), and fatigue/nausea/diarrhea/arthralgia/dry skin/dyspnea/edema (4 each). As of 2/6/20, 2 had partial response, 7 stable disease, and 2 progression of disease as BOR. Six pts had tumor regression. Four pts received treatment for > 6 months. Six are still on treatment. Analyses of research biopsies (bxs) (8 had pre-treatment bxs, 6 had an additional on-treatment bx) will be presented. Conclusions: Durva plus RAI is safe and well tolerated. The preliminary efficacy signal in this small cohort is promising. Understanding how RAI plus PD-L1 targeting impacts the tumor immune microenvironment may guide how RAI should be evaluated in future ICB trials. Clinical trial information: NCT03215095 .

6088 Background: ATC is a rare and aggressive cancer with very limited treatment options. The thyroid is one of the most immunogenic organs in the body and PD-L1 is commonly expressed on ATC tumor cells and PD-1 in the inflammatory cells in the ATC microenvironment. However, antibodies to PD-1 as single agents have a poor record in this disease. Methods: This study evaluated the addition of T (75 mg every 4 weeks up to 4 doses) to D (1500 mg every 4 weeks). SBRT 9Gy x 3 fractions was given within the first 2 weeks of treatment to produce an “abscopal” effect. Major inclusion criteria: Metastatic ATC; ECOG PS 0-2; No prior immunotherapy; Last anti-cancer treatment > 7 days prior to starting study. Primary objective 1-year overall survival with target of ≥ 2 out of 12 patients. Results: 12 patients were accrued. Male – 50%; Median PS 1; Median Age – 71 (49-82); Prior radiation to neck (75%); Prior chemotherapy (75%). MSI-High was noted in 2/11 subjects. BRAFV600E mutation in 3/12 subjects. There were 0 confirmed responses and only 1 subject with SD for 4 cycles or longer. Median time on treatment was 11 weeks (1-28+ weeks). MSI status did not affect treatment response. MSI-High patients were on treatment before progression for 8-14 weeks. Median overall survival was 14.5 weeks with only one person alive past 1 year. Neither the presence of a BRAF or p53 mutation appeared to affect either outcome. Conclusions: T/D with SBRT was not active in metastatic ATC. Future studies looking at other novel immunotherapy combinations in ATC should be evaluated. Biopsies done on study are being analyzed. Clinical trial information: NCT03122496.

6079 Background: Cis is the gold standard radiosensitizer for CRT to treat head and neck cancer. Prospective trials have required that cis be administered early in the week (Mon/Tues) to optimize radiosensitization without evidence to support this practice. This retrospective analysis considers the impact of cis day of week (DOW) administration and other variables on OPSCC pt outcomes. Methods: We reviewed OPSCC cases treated with primary CRT at our center. Pts treated with non-cis or induction chemotherapy were excluded. Data collected includes age, DOW (Mon/Tues vs Wed/Thurs/Fri), smoking status, total dose (TD) of cis (≤200mg/m2 vs > 200mg/m2), single dose (SiD) [100mg/m2 x1 day] vs split dose (SpD) [50mg/m2 x2 days] administration, T stage (0-2b vs 2c-3), N stage (0-2b vs 2c-3), overall survival (OS) (from start of RT), local/regional/distant failure, KPS and HPV/p16 status. Univariate Cox proportional hazards regression was used to analyze OS and multivariate Cox proportional hazard model investigated the relationships between OS and cis dosing variables while controlling for other factors. Results: 745 pts with OPSCC were treated with CRT from 7/31/2001-2/7/2014. 459 used cis based regimens and were included. Median age at start of RT was 55. 311 pts (67.8%) received SpD, 124 (27%) received SiD, 8 (1.7%) received weekly cis and 16 (3.5) received mixed cycles. 269 (58.6%) received ≤200mg/m2. 232 (50.5%) were HPV/p16 positive, 40 (8.7%) were negative and 187 (40.7%) were unknown. Median f/u was 7.9yrs (1.8m -18.9yrs). There were 92 (20%) deaths, and 75 (16.4%) recurrences (local/regional and distant) with 44 (9.6%) competing events. In univariate analysis, age, N stage, T stage, KPS and HPV/p16 status were significantly associated with OS, while DOW, TD, and SiD/SpD were not. In multivariate analysis (MVA), none of the associations between cis dosing and OS were significant (although MVA was limited by low number of events and total variables included). Conclusions: This retrospective analysis suggests that the DOW cis is given has no impact upon CRT outcomes for OPSCC pts. SpD cis represents an alternative administration approach.

6084 Background: R/M ACC is a malignant neoplasm most commonly of salivary gland origin with no standard treatment. The impact of combined PD-1/CTLA-4 checkpoint blockade in R/M ACC is unknown. Methods: In a two-stage minimax phase II trial, pts with progressive R/M ACC (non-salivary primaries allowed) were enrolled and treated with nivolumab 3 mg/kg every 2 weeks plus ipilimumab 1 mg/kg every 6 weeks (1 cycle = 6 weeks). Imaging, using RECIST v1.1 response assessment, was scheduled to be performed approximately every 12 weeks. The primary endpoint was overall response rate (ORR = complete response [CR]+partial response [PR]) per RECIST v1.1. To detect a difference between an unacceptable ORR of 5% and a desirable ORR of 20% (one-sided type I error of 10%, power of 90%), at least 1 in the first 18 pts required an observed response. At least 4 responses of 32 total pts were needed to meet the primary endpoint. Treatment beyond progression of disease (PD) was allowed at the discretion of the investigator. A second cohort of pts with non-ACC salivary cancer is still accruing for separate analysis. Results: From 6/12/2017-6/20/2018, 32 pts were enrolled and evaluable for the primary endpoint. There was 1 confirmed PR in the first 18 pts, therefore enrollment of the second stage continued. ORR was 6% (2/32). One additional pt had an unconfirmed PR (-31% regression before CNS PD). For best overall response, there were 2 PRs, 15 SD, and 11 PD. Four pts never reached a first disease assessment: 3 due to death from clinical PD and 1 was removed for toxicity. Six pts discontinued the trial for toxicities (Grade 4 (G4) neutropenia/sepsis and G3 adrenal insufficiency (1), G2 hypophysitis (2), G3 arthritis > 7 days (1), G3 colitis (1), and G3 hepatitis/G4 creatinine kinase (CK) elevation (1)). The 2 confirmed PRs consisted of -73.1% and -58.4% regressions, with a duration of therapy of 18.4 and 7.8 months, respectively (treatment ongoing for both). Conclusions: The study did not meet its primary endpoint, though the responses observed were dramatic. Paired biopsy and peripheral blood samples will be analyzed to elucidate insights into mechanisms of response and resistance to dual checkpoint blockade. Clinical trial information: NCT03172624.