Among patients with HIV-associated squamous cell carcinoma of the anal canal (SCCAC), the addition of cetuximab to definitive chemoradiation (CRT) reduces locoregional failure rates but is associated with grade 4 toxicity in about 25% of patients and recurrence in a 20%, according to a study published in the Journal of Clinical Oncology.1

SCCAC is associated anogenital human papillomavirus (HPV), HIV infection, and high locoregional failure fates. Cetuximab has been shown to improve the efficacy of radiotherapy in HPV-related oropharyngeal SCC. Researchers therefore evaluated whether combined modality therapy with cetuximab and definitive CRT would reduce the rates of locoregional failure in patients with HIV and stage I, II, or III anal cancer.

For the open-label, phase 2 study (ClinicalTrials.gov Identifier: NCT00324415), investigators enrolled 45 patients with stage I to III SCCAC and HIV infection. All participants received 45 to 54 Gy radiation treatment to the primary tumor and regional lymph nodes plus 8 weekly doses of concurrent cetuximab and 2 cycles of cisplatin plus fluorouracil.

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Forty-two percent (95% CI, 28-56) of patients had locoregional failure at 3 years compared with a 35% LRF rate from historical data.

In a post analysis using definitions and methods consistent with historical data, the 3-year locoregional failure rate was 20% (95% CI, 10-37).

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Seventy-two percent (95% CI, 56-84) of patients were free of progression or alive at 3 years, and 79% (95% CI, 63-89) were alive at 3 years. Twenty-six percent of patients had grade 4 adverse events; 4% of deaths were related to treatment.

Although adding cetuximab to definitive CRT may be associated with lower rates of LRF, the high rates of recurrence and grade 4 toxicity suggest the continued need for investigating more effective and less toxic therapies.

Reference

  1. Sparano JA, Lee JY, Palefsky J, et al. Cetuximab plus chemoradiotherapy for HIV-associated anal carcinoma: A phase II AIDS Malignancy Consortium trial. J Clin Oncol. 2016 Dec 12. doi: 10.1200/JCO.2016.69.1642 [Epub ahead of print]

Topics:

Anal Cancer Gastrointestinal Cancer