Maxygen, Inc, a biopharmaceutical company focused on developing improved versions of protein drugs, said its phase IIa trial of MAXY-G34 for the treatment of chemotherapy-induced neutropenia showed positive progress.

Patients in the initial 10 mcg/kg MAXY-G34 cohort met the safety criterion for duration of neutropenia (less than or equal to five days of severe neutropenia). In these trial conditions, severe neutropenia typically lasts approximately seven days without G-CSF support.

No serious adverse events or immunogenicity issues were noted for the initial cohort of patients on 10 mcg/kg of MAXY-G34. Data available from multiple patients after multiple doses revealed no binding antibodies, and drug response in all patients has been sustained.

The Data Safety Monitoring Board overseeing the trial approved escalation to the second dose level of 30 mcg/kg MAXY-G34. The first cohort of patients at this level is enrolled and currently undergoing treatment.

To date, no serious adverse events or drug-related grade 3 or 4 adverse events have been reported in any patient receiving MAXY-G34. A total of 23 doses of MAXY-G34 have been delivered to patients in the 10 mcg/kg and 30 mcg/kg cohorts.

The phase IIa trial, which is being conducted at 16 centres in Eastern Europe, is the first trial of MAXY-G34 in patients. Approximately 30 patients with Stage I-IIIa breast cancer will undergo TAC (docetaxel, adriamycin and cyclophosphamide) chemotherapy followed by next-day administration of either MAXY-G34 or Neulasta. The trial is designed as a multiple ascending dose study, with planned doses at 10, 30, 60, and 100 mcg/kg of MAXY-G34 or 6mg of Neulasta. Both MAXY-G34 and Neulasta will be administered as a single subcutaneous injection once per chemotherapy cycle.

The primary objective of the phase IIa trial is to evaluate safety and efficacy of MAXY-G34 in TAC-treated breast cancer patients and to identify one or more doses of MAXY-G34 that effectively treat chemotherapy-induced neutropenia. Patient tolerability, safety, and immunogenicity will be monitored and assessed. Data will also be collected on the pharmacokinetic properties of MAXY-G34 and the mobilization of CD34+ stem cells.

MAXY-G34 is a novel pegylated granulocyte colony stimulating factor (PEG-GCSF) designed to treat chemotherapy-induced neutropenia. Preclinical and phase I studies show MAXY-G34 to have novel and potentially superior properties compared to the current PEG-GCSF therapy, Neulasta. GCSF is a natural protein that stimulates the body's bone marrow to produce neutrophils, a specific type of white blood cell that plays an important role in the defense against bacterial infections. Worldwide sales of GCSF products were approximately $4 billion in 2006.

Neutropenia is a severe decrease in neutrophil cell counts in the blood. Neutropenia is a common side effect of chemotherapeutic treatments for many forms of cancer, including breast cancer, lung cancer, lymphomas and leukaemias. Neutropenic patients are at increased risk of contracting bacterial infections, some of which can be life threatening. Further, and most importantly, neutropenic patients may receive reduced or delayed chemotherapy treatment, which can result in cancer progression.