Accelerated RT Plus Panitumumab Fails To Improve PFS For Head And Neck SCC

Cisplatin plus standard radiotherapy continues to be standard of care for patients with locoregionally advanced squamous cell carcinoma of the head and neck

medwireNews: Research suggests that accelerated radiotherapy (RT) with panitumumab is not superior to a standard regimen plus cisplatin for the progression-free survival (PFS) of patients with locoregionally advanced squamous cell carcinoma (SCC) of the head and neck.

The results of the Canadian Cancer Trials Group Study HN.6 mean that standard RT plus cisplatin “remains the standard of care” in this population, say Lillian Siu, from the Princess Margaret Cancer Centre in Toronto, Ontario, Canada, and co-authors in JAMA Oncology.

The phase III open-label trial included patients with SCC of the oral cavity, oropharynx, larynx or hypopharynx who had been staged as T(any), N+, M0 or T3–4, N0, M0 and had an ECOG performance status of 0 or 1.

Two-year PFS was achieved by 73% of the 160 patients who were randomly assigned to receive cisplatin 100 mg/m2 on days 1, 22 and 43 of RT, consisting of 70 Gy given in 35 fractions over 7 weeks.

And this was comparable to the 76% rate achieved by the 160 patients who were given the epidermal growth factor receptor inhibitor panitumumab at a 9 mg/kg dose over 60–90 minutes every 3 weeks, beginning a week before RT. In this trial arm, RT consisted of 70 Gy delivered in 35 fractions over 6 weeks, with a twice-daily treatment given once per for week for the first 5 weeks.

Nor did 2-year overall survival differ significantly between the cisplatin and panitumumab treatment groups, at 85% versus 88%.

Adherence to RT delivery was “high” at 98% for both treatment groups but patients given the cisplatin regimen were less likely to complete three treatment cycles than those using panitumumab (63 vs 91%) and had a higher cumulative dose, “suggesting that the overall systemic treatment dose intensity was greater” with panitumumab, the researchers note.

Safety analysis showed that the cisplatin regimen was associated with higher rates of grade 3 or more severe symptoms of ototoxicity, gastrointestinal toxicity, renal toxicity and weight loss, while panitumumab-treated patients were more likely to report symptoms of skin toxicity or mucositis.

There was no significant difference in the quality of life of the two patient groups, as measured by the changes in score between baseline and 1 year on the Functional Assessment of Cancer Therapy–Head and Neck Questionnaire.

Despite the negative trial results, the investigators believe that the HN.6 trial “provided a platform” for a detailed assessment of quality of life and swalling symptoms and function in this patient population, leaving an “invaluable source of data to characterize the impact of disease and treatment from the patient perspective”.

Noting that the findings may be attributed to choice of panitumumab versus cetuximab and the trial’s design in an era before understanding of the significance of human papillomavirus in SCC of the head and neck, they conclude: “A clinically well-annotated repository of tumor and blood-based biospecimens has been collected as part of the correlative science objective of this study, which will be germane to hypotheses-generated translational research to better elucidate the role of EGFR inhibition in this disease.”

Reference

Siu LL, Waldron JN, Chen BE, et al. Effect of standard radiotherapy with cisplatin vs accelerated radiotherapy with panitumumab in locoregionally advanced squamous head and neck carcinoma: A randomized clinical trial. JAMA Oncol; Advance online publication 8 December 2016. doi:10.1001/jamaoncol.2016.4510

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