Accelerated Modulated Fractionation (SIB-IMRT) for Head and Neck District

Radiobiological rationale Overexpression of EGFR has been found to be involved into two different mechanisms of response to ionizing radiations: the former is related to the increased cell proliferation rate, the latter leading to lower radiosensitivity.

1. Increasing of cell proliferation rate From an analysis of the already reported evidences, we quantified the effect of a higher cell proliferation rate due to overexpression of EGFR. These findings were reported in patients affected with squamous carcinoma of head and neck district and evaluated for EGFR status. In those patients, local recurrence was compared in patients with different length of treatment but at the same fractionation. Consequently, the real doubling time in the subgroups with high and low EGFR expression was extrapolated . From these extrapolated values, equivalent doses of each day of non-delivered treatment have been calculated for patients who received accelerated schedule. Furthermore, doses were reported in relation to the different primary sites (oropharynx, larynx, oral cavity, hypopharynx).

Modification of doubling time (TD) of neoplastic cell population in patients with Low and High EGFR expression.
2. Reduction of radiosensitivity Unfortunately, how radiosensitizing drugs can modify radiosensitivity cannot be evaluated retrospectively. Actually, the efficacy is evaluated on the basis of an overall effect of the treatment but radiosensitivity changes day by day in radiation and pharmacological concurrent treatment. However, these changing in radiosensitivity can be analysed in pre-clinical setting. In many reports, a progressively higher radiosensitivity has been shown in cellular survival curves by increasing EGFR inhibitor concentration. Nevertheless, the concentrations of EGFR inhibitor do not correspond to in vivo concentration during radiotherapy delivery. Fortunately, this data is obtainable from Cetuximab pharmacokinetic curve. Therefore, cell survival curves corresponding to drug concentration were obtained by performing a graphic interpolation. From these curves, daily radiosensitivity parameters were found.

Subsequently, daily doses with respect to daily radiosensitivity were identified by radiobiological calculation model. This fractionation, designed on Cetuximab pharmacokinetics, have been calculated to be equivalent to curative treatment (70Gy given with conventional schedule).

At the same time, lower cutaneous toxicity is expected with this "modulated" schedule due to the possibly increased cellular repair. Pharmacokinetics data of Cetuximab we found on the population: Vmax 4.38mg/h (15.4%), Km 74g/ml, central compartment volume Vl 2.83 l (18.6%), peripheral compartment volume 2.43 l (56.4%) and intercompartmental clearance 0.103 l/h (97.2%). Those parameters remain unmodified also during prolonged therapies. Administrated doses have been found to be adequate to cell wall receptors saturation.

A definition of overexpression of EGFR is still lacking. Different cut-offs have been proposed to distinguish patients with "high expression" from patients with "low expression" of EGFR. In a recent study the adoption of accelerated fractionation showed an advantage for those patients with an expression of EGFR>50%. Thus, we adopted this cut-off in our study.

• Cetuximab plus Radiotherapy (Drug), also known as Radiotherapy, IMRT: Standard dose of a curative radiotherapy treatment is 70Gy given with conventional fractionation (2G daily) in an overall length of 7 weeks. In this study, the fractionation has been modified accordingly Cetuximab pharmacokinetics. Cetuximab will be administered with standard schedule: charge dose of 400mg/mq a week before the beginning of concurrent treatment, then weekly doses of 250mg/mq intravenous for 7 administration. This schedule to obtain the same biological efficacy on tumour with lower toxicity on healthy tissues.

Primary outcomes

• Number of patients who experienced acute toxicity with Grade 3 or Grade 4 adverse events according to Scala CTCAE v4.0 toxicity criteria and scale Radiation Therapy Oncology Group/European Organisation for Research and Treatment of Cancer (RTOG / EORTC) [up to 7 days during RT treatment]: During radiotherapy, patients will be assessed weekly for acute toxicity using validated international scales.acute toxicity will be assessed with CTCAE V 4.03 (Common Terminology Criteria of Adverse Events Version 4.03) scale. Furthermore pain (NRS pain scale) nutritional assessment (weight in kilograms ) will be performed.

Secondary outcomes

• Number of patients who experienced late toxicity with Grade 3 or Grade 4 adverse events according to Scala CTCAE v4.0 toxicity criteria and scale RTOG / EORTC [up to 6-8 weeks after treatment completion and then up to 2 years]: Patients will be assessed weekly for late toxicity using validated international scales.acute toxicity will be assessed with CTCAE V 4.03 (Common Terminology Criteria of Adverse Events Version 4.03) scale.
• Number of patients who experienced local or distance recurrence of disease assessed through clinical and radiological controls [up to 6-8 weeks after treatment completion and then up to 2 years]: Clinical assessment will be performed through: 1. Otolaryngology examination and laryngoscopy Radiological assessment will be performed through: 2. Facial skeleton and neck MRI with and without contrast or CT with and without contrast if MRI is unfeasible.

Sex: All, ages: 18 Years to 90 Years

Inclusion Criteria:

* Patients with histological proof of locally advanced squamous carcinoma of oropharynx, larynx, hypopharynx (stage III and Iva)
* Overexpression of EGFR (>50%)
* Patients previously considered non-eligible for curative radio-chemotherapy for clinical reasons.
* Performance Status (ECOG) ≤ 2
* Age ≥ 18 years
* Possibility of correct administration of treatment
* Written informed consent

Exclusion Criteria:

* Distant metastases
* Oral cavity or rhinopharynx neoplasm
* Need of cutaneous bolus
* Previous treatments on head and neck district
* Collagenopathies or other severe systemic disease
* Severe cardiopathies or myocardial infarction in the previous 12 months, serious hepatopathies or other diseases with heavy impact on general conditions.
* Psychiatric disorders or other conditions preventing from expressing informed consent.

• Roberto Orecchia, Prof, Study director, European Institute of Oncology