A new-generation lung cancer drug has shown an impressive ability to prevent disease progression when administered as a first-line treatment in patients with advanced disease, investigators reported at the 35th Congress of the European Society for Medical Oncology (ESMO).

Preliminary results from an ongoing Phase-II trial of the drug PF299804 (PF-299) showed that close to 85% of patients whose cancers harbor mutated forms of the EGFR gene have remained progression-free for at least nine months, reported Dr Tony Mok from the Chinese University of Hong Kong.

While some existing drugs reversibly inhibit the cancer-linked receptor HER-1 (also known as EGFR), PF-299 is a 'pan-HER' inhibitor, which irreversibly inhibits several members of the HER family, including EGFR, HER-2 and HER-4.

"We know that PF-299 is a different compound than drugs such as erlotinib and gefitinib, targeting multiple receptors on the HER pathway," Dr Mok said. "We also know from preclinical work that PF-299 inhibits signaling in both wild-type and mutant EGFR, including forms of NSCLC that are resistant to EGFR inhibitors such as erlotinib and gefitinib."

The current trial includes patients with advanced non-small cell lung cancer and no prior systemic treatment for their disease. All were either non-smokers or light smokers, or were known to have EGFR mutations.

So far, 74 of 80 planned patients have enrolled. Of the 41 with known EGFR status, 27 had activating mutations.

Each patient was administered either 30mg or 45mg of PF-299 once daily, and were assessed every 28 days. After 9 months of treatment, 57.1% of patients overall, and 84.7% of those patients with EGFR mutations, remained progression-free, Dr Mok reported. The expected median progression-free survival with standard-of-care chemotherapy in this patient population is approximately six months.

"Even though these data are preliminary and patients are still being followed, the percentage of patients with EGFR mutations who are progression-free at six months is particularly promising, with 85% of patients remaining progression-free by nine months," Dr Mok said.

"We are excited by these encouraging early results, as they support our hypothesis that these next generation agents targeting multiple receptors on the HER pathway may offer an advantage," he said.

Dr Mok noted that in another study recently presented, PF299 was reported to be better than erlotinib in a randomized head-to-head Phase-II study in patients with advanced NSCLC who had progressed on at least one prior chemotherapy regimen.

"Our new results, even though preliminary, also suggest that PF-299 could offer an improvement over currently available options as a first-line treatment in both Asian and non-Asian patients with advanced NSCLC selected for likelihood of an EGFR activating mutation."

""The results of this trial are encouraging, particularly because 85% of EGFR-mutated patients treated with PF-299 as first-line remained progression-free at 9 months," commented Dr Enriqueta Felip, from Vall d'Hebron Hospital in Barcelona, Spain.

Source: ESMO