The US Food and Drug Administration (FDA) has granted breakthrough therapy designation to Boehringer Ingelheim's  volasertib, a selective and potent polo-like kinase (Plk) inhibitor, for the treatment of patients with acute myeloid leukaemia (AML), a type of blood cancer.

Professor Klaus Dugi, corporate senior vice president Medicine, Boehringer Ingelheim said, "Volasertib" innovative mode of action offers a new approach and may potentially provide a new therapy option for AML patients who have a high unmet medical need." Professor further added, "We are looking forward to exploring opportunities with the FDA to expedite the final stage of the development of volasertib with the aim of making this treatment available for patients."

The Breakthrough Therapy designation pathway was launched by the US Food and Drug Administration (FDA) in 2012, and is intended for any drug that "treats a serious or life-threatening condition and preliminary clinical evidence indicates that the drug may demonstrate substantial improvement on a clinically significant endpoint(s) over available therapies."

A phase II study in patients with previously untreated AML ineligible for intensive therapy compared volasertib in combination with the established therapy of low-dose cytarabine (LDAC) versus LDAC alone. The primary endpoint for the phase II study was objective response. Objective responses were observed in 31 per cent of patients (13 of 42 patients) treated with the combination of volasertib plus LDAC compared to 13.3 per cent of the patients (6 of 45 patients) treated with LDAC alone (p = 0.0523).

Secondary endpoints included event-free survival (EFS), overall survival (OS) and safety. A trend for OS benefit (8.0 months for the volasertib combination compared to 5.2 months for LDAC alone, p = 0.0996) was observed. EFS was measured from the date of randomisation to the date of disease progression (treatment failure), relapse or death from any cause, whichever occurred first. In patients treated with the combination of volasertib plus LDAC, the median EFS was 5.6 months compared to 2.3 months in patients treated with LDAC alone (hazard ratio: 0.56; 95% CI: 0.34, .93; p=0.0237).

These encouraging results led to the initiation of the phase III study, POLO-AML-2, investigating volasertib in combination with LDAC, in patients aged 65 years and above with previously untreated AML who are ineligible for intensive remission induction therapy.

"The most common treatment approach for AML is intensive remission induction therapy; however, many older patients are ineligible for this approach which involves high doses of chemotherapy which these patients are often unable to tolerate," said Professor Dugi, and added, "These patients are in particular need of new treatments and we hope that volasertib may be able to fill this gap by providing a tolerable option that improves survival related outcomes."

Volasertib is designed to inhibit the activity of Plk. Plk1 – the best characterised of the five known human Plks – is an enzyme that regulates cell division (mitosis). This inhibition results in cell cycle arrest and ultimately cell death (apoptosis).

Leukaemia is a rare cancer of the bone marrow and blood. AML is one of the most common types of leukaemia in adults.

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