Pfizer announced updated safety and efficacy results surrounding its investigational compound, CP-751,871, in patients with non-small cell lung cancer (NSCLC). These results, along with supporting correlative science data, were presented at the 33rd European Society for Medical Oncology (ESMO) congress in Stockholm, Sweden.

Results from a phase-II, randomized, non-comparative study, "Addition of CP-751,871, an anti-IGF-1R antibody, to paclitaxel and carboplatin results in high activity in NSCLC, particularly in squamous subtype," (abstract 229PD) showed 54 per cent of patients with Stage III/IV treatment-naïve NSCLC receiving the combination CP-751,871 plus carboplatin and paclitaxel (n=97) experienced objective responses. The response rate was 41 percent in patients treated with carboplatin and paclitaxel alone (n=53).

In addition, 78 per cent of a subset of patients with squamous cell carcinoma (n=9) and 57 per cent of a subset of patients with adenocarcinoma (n=28) receiving 20 mg/kg of CP-751,871 plus carboplatin and paclitaxel experienced objective responses. Response rates were 46 per cent and 25 per cent, respectively, for squamous cell (n=12) and adenocarcinoma patients (n=20) receiving carboplatin and paclitaxel alone. No response advantage with CP-751,871 was seen in a subset of patients with undifferentiated tumours.

"These data contribute to our evolving understanding of the potential safety and efficacy of CP-751,871 in patients with NSCLC, a devastating disease -- an estimated 1.5 million new cases are expected worldwide this year - with limited treatment options," said study presenter Luis Paz-Ares, chief, division of Medical Oncology, Virgen del Rocio University Hospital, Seville, Spain.

Patients who received CP-751,871 20 mg/kg showed the greatest improvement in progression-free survival (PFS). PFS was defined as either the length of time before the cancer progressed or death.

Twenty of the 53 patients in the carboplatin and paclitaxel arm crossed over to receive CP-751,871. Without censoring for crossover, the median PFS in patients receiving no CP-751,871, 10 and 20 mg/kg of CP-751,871 plus carboplatin and paclitaxel were 4.3, 3.6 and 5 months respectively. The median PFS in squamous cell patients receiving 20 mg/kg of CP-751,871 plus carboplatin and paclitaxel was 5.6 months (4.3 months for patients with squamous cell cancer treated with carboplatin and paclitaxel alone).

After censoring for crossover, median PFS in patients receiving no CP-751,871, 10 and 20 mg/kg of CP-751,871 plus carboplatin and paclitaxel was, respectively, 3.5, 3.6 and 5 months.

The side effects of CP-751,871 were generally manageable. The most common Grade 3 or 4 side effects reported in this study were fatigue (10 percent), hyperglycaemia (increased blood sugar) (20 percent) and neutropenia (30 percent).

Additional study results presented by Antonio Gualberto, director and Global Clinical Leader (Oncology), Pfizer Global Research and Development, New London, CT, at the meeting expand the understanding of the relationship between IGF-1R inhibition and the activity in different populations of NSCLC patients. Results of the correlative science study, "IGF-1R markers in NSCLC patients on anti-IGF-1R therapy," (abstract 1320) conducted to investigate the molecular composition of lung tumours and its relevance to anti-IGF-1R therapy showed that members of the IGF-1R pathway appear to be expressed differentially across lung tumour histologies, which may explain the differential activity of CP-751,871 across these histologies.

"These data provide greater insight into the potential relationship between tumour histology and response to CP-751,871 observed in the clinical studies," said Dr Gualberto. "Furthermore, the results support the global phase-III clinical trial programme for CP-751,871 in NSCLC."

CP-751,871, a fully human monoclonal antibody, is a highly specific inhibitor of the IGF-1R pathway. The IGF-1R pathway is one of the key signalling pathways in cancer cells that lead to uncontrolled growth and survival of tumour cells.

Pfizer Oncology is committed to the discovery, investigation and development of treatments and currently has 22 innovative compounds in clinical development across four platforms.