Some of the views expressed in the following notes on newly approved products should be regarded as preliminary, as there may have been limited published data at the time of publication, and little experience in Australia of their safety or efficacy. However, the Editorial Executive Committee believes that comments made in good faith at an early stage may still be of value. Before new drugs are prescribed, the Committee believes it is important that more detailed information is obtained from the manufacturer's approved product information, a drug information centre or some other appropriate source.

Stemgen (Amgen Australia)
vials containing 1.875 mg as powder for reconstitution
Approved indication: stem cell transplant
Australian Medicines Handbook Section 14.2

Some cancer treatments require the patient to have an autologous stem cell transplant after chemotherapy. The cells for transplant are collected before treatment. Granulocyte colony stimulating factor (G-CSF) is often used to increase the number of circulating haemopoietic precursor cells available for collection. Ancestim has been developed for use with G-CSF to further increase the number of cells which can be harvested for transplant. It is a recombinant form of human stem cell factor, the protein which normally stimulates stem cell production.

Ancestim and G-CSF have been compared with G-CSF alone in 205 women with breast cancer. The objective was to collect a target number (5 x 10⁶/kg)of CD34⁺ cells. Treatment continued until the target was reached or aphoresis had been carried out five times. The proportion of the patients given the combination who reached the target was 63% compared with only 47%of the patients given G-CSF alone. Fewer collections were needed in the combination group; a median of four aphoresis procedures was required.

Everyone prescribed ancestim must be given a bronchodilator and H₁ and H₂ antagonists before each subcutaneous injection. There is a risk that ancestim will stimulate mast cells and cause allergic reactions. Nearly all patients will experience an injection site reaction. Other common adverse effects include respiratory symptoms, paraesthesia and rashes.

The stimulant effect of ancestim may promote the growth of tumour cells. Particular caution is needed if the drug is considered for use in patients with myeloidmalignancies, melanomas, or small cell lung cancers.

While ancestim has achieved its targets for efficacy, there is little information on its benefits for the patients. Although the patients may be spared additional aphoresis, it is unknown if adding ancestim to G-CSF will ultimately improve end-points such as survival.