Abstract CT227: MC1273: Phase II evaluation of aggressive dose de-escalation for adjuvant chemoradiation in HPV associated oropharynx cancer

Abstract

Abstract Background: Traditional adjuvant therapy for oropharyngeal squamous cell carcinoma (OPSCC) consists of 60-66 Gy of radiation therapy (XRT) given in 2 Gy daily fractions along with high dose cisplatin if the patient has high risk factors. Despite the excellent cure rates for HPV+ OPSCC, one in three patients treated with conventional treatment will develop grade >3 long-term sequelae from therapy. There is intense interest in de-intensifying adjuvant therapy for this patient population in order to maximize quality of life while maintaining excellent historical rates of disease control. Methods: MC1273 is a phase II non-randomized trial open at Mayo Clinic Rochester testing a novel course of aggressive therapy de-escalation following surgery for HPV+ OPSCC. The primary endpoint is local/regional control at 2 years while secondary endpoints include toxicity and quality of life (QOL). The eligibility criteria include all patients with p16-positive OPSCC with less than a ten pack-year smoking history who have had a complete surgical resection. Exclusion criteria include positive surgical margins, prior history of malignancy, and history of connective tissue disorders. Patients are divided into two prospective cohorts depending upon risk factors found at surgery. Patients with intermediate risk disease (≥T3, ≥N2, lymphovascular invasion, or perineural invasion) are enrolled in MC1273A while patients with extracapsular extension (ECE) are enrolled in MC1273B. Patients on MC1273A receive 30 Gy of radiation delivered in 1.5 Gy twice-daily fractions over the course of two weeks along with weekly docetaxel (15 mg/m2) given on day 1 and day 8. Patients on MC1273B receive a similar treatment regimen but also have the nodal level with positive ECE concurrently boosted to 36 Gy in 1.8 Gy twice-daily fractions. In addition to standard of care follow-up, patients receive a swallowing assessment with speech therapy immediately before XRT, one month post-XRT, and one year post-XRT. Patients also have QOL assessment consisting of the XeQOLS, Eq-5D, FACT H&N (Vers 4) and Dermatology Life Quality Index assessed at pre-XRT and 3, 12, and 24 months post-XRT. Results: Each cohort of MC1273 is powered to detect a 10% local/regional failure rate with 85% confidence. Each cohort will accrue 35 evaluable patients and 5 additional patients to account for ineligibilities and violations (40 patients total per cohort.) MC1273A began accrual in September 2013. The first five patients were monitored for grade ≥4 acute toxicities before proceeding to open accrual. MC1273B began accrual in May 2014 and has also proceeded to open accrual. Accrual will also begin in Mayo Clinic Scottsdale in the first quarter of 2015. Conclusions: MC1273 is meeting its accrual targets and should finish accrual by 2016. We anticipate that preliminary results for toxicity will be available by 2017 and local/regional data will be available by 2018. Citation Format: Daniel J. Ma, Katharine A. Price, Eric J. Moore, Joaquin J. Garcia, Scott H. Okuno, Daniel L. Price, Jeff A. Sloan, Nathan R. Foster, Robert L. Foote. MC1273: Phase II evaluation of aggressive dose de-escalation for adjuvant chemoradiation in HPV associated oropharynx cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr CT227. doi:10.1158/1538-7445.AM2015-CT227