Eligibility criteria

Chemotherapy naïve patients, aged ≥ 18 years with histologically documented mCRC were enrolled; other eligibility criteria included: patients who had received prior adjuvant 5-FU-based chemotherapy were eligible if they had remained free of disease for at least 6 months after the completion of adjuvant therapy; performance status (ECOG) 0–2; at least one bidimensionally measurable lesion of ≥ 2 cm; a life expectancy of at least 3 months; adequate hematologic parameters (absolute neutrophil count ≥ 1.5 × 10⁹/L and platelets ≥ 100 × 10⁹/L); creatinine and total bilirubin ≤ 1.25 times the upper limit of normal; aspartate and alanine aminotransferases ≤ 3.0 times the upper limit of normal; absence of active infection or malnutrition (loss of more than 10% of body weight); absence of a second primary tumor other than non-melanoma skin cancer or in situ cervical carcinoma; patients receiving palliative radiotherapy had to have measurable metastatic disease outside the irradiation fields.

Patients with operable metastatic disease, clinically significant cardiovascular disease or major surgery within one month prior to study registration were excluded from the study. Other exclusion criteria included: pregnancy or lactation, regular use of aspirin (more than 325 mg per day) or other nonsteroidal anti-inflammatory agents; preexisting bleeding diatheses or coagulopathy or the need for full-dose anticoagulation; history of deep vein thrombosis within one year prior to registration; uncontrolled hypertension; pre-treatment proteinuria grade 2 or more and known central nervous system metastases. Patients with chronic diarrhea, or prior irradiation affecting more than 30% of the active bone marrow were also excluded. The study was approved by the Ethics and Scientific Committees of each participating center. All patients gave written informed consent in order to participate in the study.

Chemotherapy

Bevacizumab (Avastin^®; Roche, Bale, Suisse) was given prior to chemotherapy at a dose of 5 mg/kg every 2 weeks, as a 2-hours infusion intravenous (IV) during the first cycle, as a 1-hour IV infusion during the second cycle and as a 30 min IV infusion in the subsequent cycles; L-OHP (Eloxatin^®; Sanofi-Aventis, Collegeville, USA) was administered on day 1 at the dose of 85 mg/m² as a 2-hours IV infusion; LV was given at the dose of 200 mg/m² as a 2-hour IV infusion, followed by 5-FU 400 mg/m² as IV bolus, and then, 600 mg/m² as a 22-hour continuous IV infusion, on days 1 and 2. Routine antiemetic prophylaxis with a 5-hydroxytryptamine-3-receptor antagonist was used in both study groups. Treatment was administered every 2 weeks until disease progression or unacceptable toxicity, or until the patient declined further treatment. No maintenance therapy with Bevacizumab after chemotherapy discontinuation was planned.

Patients were assessed for toxicity before each cycle using the National Cancer Institute Common Toxicity Criteria [13]. Chemotherapy was delayed until recovery if neutrophils were less than 1.5 × 10⁹/L or platelets less than 100 × 10⁹/L or for significant persisting nonhematologic toxicity. Doses of LOHP and 5-FU were reduced by 15% in subsequent cycles in case of grade 4 neutropenia or grade 3–4 thrombocytopenia lasting for more than 3 days or in case of febrile neutropenia. No prophylactic administration of granulocyte colony-stimulating factor (G-CSF) was allowed. G-CSF was used for the treatment of febrile neutropenia. Doses of 5-FU was reduced by 15% in subsequent cycles in case of grade 2–4 diarrhea, stomatitis or dermatitis. L-OHP dose was reduced by 15% in cases of persistent (≥ 14 days) paresthesia or temporary (7 to 14 days) painful paresthesia or functional impairment. In cases of persistent (≥ 14 days) painful paresthesia or functional impairment, L-OHP was omitted in subsequent cycles until recovery. Bevacizumab was permanently discontinued in patients developing gastrointestinal perforation, wound dehiscence requiring medical intervention, serious bleeding, nephrotic syndrome, or hypertensive crisis. Temporary discontinuation of Bevacizumab administration was implemented in patients with evidence of moderate to severe proteinuria and in patients with severe hypertension that was not controlled with medical management. Doses of bevacizumab and chemotherapy were recalculated if the patient's weight changed by more than 10 percent during the study.

Patients' evaluation

Pre-treatment evaluation included a detailed medical history and physical examination, a complete blood cell count (CBC) with differential and platelet count, blood chemistry, urine analysis, serum levels of carcinoembryonic antigen (CEA) and computed tomography scans (CT) of the chest and abdomen. Pretreatment evaluation had to be performed within 2 weeks prior to study entry. During treatment, a CBC with differential and platelets count was performed weekly and in case of grade 3–4 neutropenia, thrombocytopenia or febrile neutropenia it was performed daily until hematologic recovery. In addition, patients were clinically assessed and blood chemistry and urine analysis were performed before each treatment cycle. Response to treatment was evaluated every 2 months (4 chemotherapy cycles) or sooner if clinically indicated. After the treatment period the patients without disease progression, were evaluated with clinical examination and CT scans every 2 months.

The Response Evaluation Criteria in Solid Tumors (RECIST) were used to assess tumour responses [14]. Complete response was defined as disappearance of all disease without the appearance of new lesions. Partial response was defined as a reduction of at least 30% in the sum of the products of the longest diameters of all measurable lesions. Disease progression was defined as an increase of at least 20% in measurable tumor or an unequivocal increase in the size of non-measurable lesions or the appearance of new lesions. After partial response, tumor measurements exceeding 20% of the maximal extent of a previously observed reduction constituted progression. Patients who did not meet the definitions of response or progression were classified as having stable disease. All objective responses were confirmed by a follow-up CT scan at least 4 weeks following documentation of the response.

Statistical Considerations

The primary end point of the study was the tumor response rate. The study followed the optimal Simon two-step design. If a minimum objective response rate exceeding 45% was observed in the first 16 patients, 35 additional patients had to be enrolled (α = 0.05, power 80%). Secondary objectives were the tolerance of the regimen as well as response duration, time to tumor progression and overall survival time. The duration of response was defined as the time from the first documentation of response to disease progression. The time to tumor progression (TTP) was determined by the interval between the initiation of treatment and the date of first documentation of disease progression or the date of death from any cause. Overall survival (OS) was defined as the time from treatment initiation to death. The follow up time was defined as the period from treatment initiation to the study's cutoff date (for alive patients). TTP and OS were estimated by the Kaplan-Meier method [15], and the confidence intervals for response rates were calculated using methods for exact binomial confidence intervals [16].

Patients' characteristics

Compliance with the treatment

Five hundred and thirty nine chemotherapy courses were administered (median, 12 courses/patient; range, 2–20). Fifty (9.3%) chemotherapy courses were delayed for a median of 7 days (range, 1–10) due to hematological (n = 21; 3.9%), non-hematologic (n = 10; 1.8%) toxicity, and for reasons unrelated to disease or treatment (n = 19; 3.6%). The median interval between cycles was 16 days (range, 14–24). Dose reduction of cytotoxic agents was required in 27 (5%) cycles because of hematologic (n = 11; 2.1%), and non-hematologic (n = 16; 2.9%) toxicity. The delivered relative dose intensity was 92% and 94% of the protocol planned doses for L-OHP and 5-FU/LV, respectively. At the time of this analysis, 49 (92.4%) patients have discontinued treatment for the following reasons: progressive disease (n = 40 patients), unacceptable neurotoxicity (n = 6 patients), death without disease progression (n = 3 patients).

Treatment efficacy

In an intention-to-treat-analysis eight (15.1%) patients achieved a documented complete response (CR) and 28 (52.8%) a partial response (PR), for an overall response rate (ORR) of 67.9% (95% C.I.: 53.8%–92%). All objective response were documented with a following CT scan at least 4 weeks later. In addition, 11 (20.8%) patients had stable disease (SD) and six (11.4%) progressive disease (PD). The median response duration was 8 months (range, 3–21.2) and the median time to initial documentation of response was 2 months (range, 2–4). The median TTP was 11 months (range, 0.6–28) (Figure 1). After a median follow-up period of 20 months (range, 0.6–38), 33 (71.7%) patients were still alive. The median overall survival time has not yet been reached (range 0.6–38.0); the probability of 1-, 2- and 3- year's survival was 79.8%, 63.8%, and 58.3 respectively.

Toxicity