Efficacy and Tolerance of Carboplatin plus Cetuximab (Simplified EXTREME Regimen) in Patients with Recurrent and/or Metastatic Head and Neck Squamous Cell Carcinoma

AIMS

The EXTREME regimen is the standard for recurrent and/or metastatic head and neck squamous cell carcinoma (HNSCC). However, many patients have a poor performance status and/or comorbidities, making them unfit for this regimen. We have treated them with carboplatin and cetuximab (simplified EXTREME regimen) since 2007. Our aim was to assess the efficacy and tolerance of this regimen in this frail population.

MATERIALS AND METHODS

A retrospective chart review of all patients treated with the simplified EXTREME regimen for recurrent and/or metastatic HNSCC in three academic hospitals between 2007 and 2017 was carried out. The primary end point was overall survival. Secondary end points were progression-free survival (PFS), overall response rate (ORR) and toxicity.

RESULTS

One hundred and three patients were included. The median age was 63 years, 40% had performance status 2-3. The median follow-up was 30.2 months. The median overall survival and PFS were 7.2 and 3.7 months, respectively. The median overall survival was 10.1 months in patients with performance status 0-1 versus 4.6 months in patients with performance status 2-3 (P = 0.01). ORR was 39%. Acute grade 3-4 haematological and non-haematological toxicity rates were 25.2% and 27.2%, respectively. Patients with grade 1 or more skin toxicity had a higher ORR (hazard ratio = 3.44; P = 0.03), a prolonged overall survival (hazard ratio = 0.37; P < 0.0001) and PFS (hazard ratio = 0.29; P < 0.0001). During treatment, 29% of patients had pain reduction, 13.5% had weight gain and 17.2% had an improvement in performance status.

CONCLUSIONS

This is the largest cohort of patients treated with simplified EXTREME for HNSCC. It was well tolerated, with a high ORR. Interestingly, skin toxicity correlated with treatment efficacy.

Evidence-Based Treatment Options in Recurrent and/or Metastatic Squamous Cell Carcinoma of the Head and Neck

The major development of the past decade in the first-line treatment of recurrent and/or metastatic squamous cell carcinoma of the head and neck (R/M SCCHN) was the introduction of cetuximab in combination with platinum plus 5-fluorouracil chemotherapy (CT), followed by maintenance cetuximab (the "EXTREME" regimen). This regimen is supported by a phase 3 randomized trial and subsequent observational studies, and it confers well-documented survival benefits, with median survival ranging between approximately 10 and 14 months, overall response rates between 36 and 44%, and disease control rates of over 80%. Furthermore, as indicated by patient-reported outcome measures, the addition of cetuximab to platinum-based CT leads to a significant reduction in pain and problems with social eating and speech. Conversely, until very recently, there has been a lack of evidence-based second-line treatment options, and the therapies that have been available have shown low response rates and poor survival outcomes. Presently, a promising new treatment option in R/M SCCHN has emerged: immune checkpoint inhibitors (ICIs), which have demonstrated favorable results in second-line clinical trials. Nivolumab and pembrolizumab are the first two ICIs that were approved by the US Food and Drug Administration. We note that the trials that showed benefit with ICIs included not only patients who previously received ≥1 platinum-based regimens for R/M SCCHN but also patients who experienced recurrence within 6 months after combined modality therapy with a platinum agent for locally advanced disease. In this review, we outline the available clinical and observational evidence for the EXTREME regimen and the initial results from clinical trials for ICIs in patients with R/M SCCHN. We propose that these treatment options can be integrated into a new continuum of care paradigm, with first-line EXTREME regimen followed by second-line ICIs. A number of ongoing clinical trials are comparing regimens with ICIs, alone and in combination with other ICIs or CT, with the EXTREME regimen for first-line treatment of R/M SCCHN. As we eagerly await the results of these trials, the EXTREME regimen remains the standard of care for the first-line treatment of R/M SCCHN.