On 11 April, 2016 the US Food and Drug Administration (FDA) approved venetoclax (Venclexta) for the treatment of patients with chronic lymphocytic leukaemia (CLL) who have a chromosomal abnormality called 17p deletion and who have been treated with at least one prior therapy. Venclexta is the first FDA-approved treatment that targets the B-cell lymphoma 2 (BCL-2) protein, which supports cancer cell growth and is overexpressed in many patients with CLL.
Patients with CLL who have a 17p deletion lack a portion of the chromosome that acts to suppress cancer growth. This chromosomal abnormality occurs in approximately 10% of patients with untreated CLL and in approximately 20% of patients with relapsed CLL.
30-year long journey for clinical use
AbbVie’s BCL-2 inhibitor venetoclax, the leading small-molecule protein-protein interaction inhibitor, is the first marketed drug to directly target the ability of cancer cells to evade apoptosis. In March 2016 issue of the Nature Reviews Drug Discovery, Asher Mullard wrote: “For proof that drug discovery can be a long and tortuous process, look no further than AbbVie’s venetoclax. The drug’s target, apoptosis regulator BCL-2, was identified 30 years ago. Drug hunters started to search for small molecules that could inhibit BCL-2 over 20 years ago. And AbbVie needed three lead candidates – and two rounds of clinical trials – to finally get a drug in front of the FDA... An approval could be transformational for the treatment of chronic lymphocytic leukaemia.”
BCL-2 was discovered in 1986. The ability to evade cell death was later recognised as one of the hallmarks of cancer. Amplifications of BCL-2 and related pro-survival genes raise the apoptotic threshold, thereby helping cancer cells to survive despite the effects of anticancer therapeutics. It led to research on therapeutic potential of BCL-2 inhibitors.
FDA approval
Dr Richard Pazdur, director of the Office of Hematology and Oncology Products in the FDA’s Center for Drug Evaluation and Research said: “For certain patients with CLL who have not had favorable outcomes with other therapies, Venclexta may provide a new option for their specific condition.”
The efficacy of Venclexta was tested in a single-arm clinical trial of 106 patients with CLL who have a 17p deletion and who had received at least one prior therapy. Trial participants took Venclexta orally every day, beginning with 20 mg and increasing over a five-week period to 400 mg. Results showed that 80% of trial participants experienced a complete or partial remission.
Venclexta is indicated for daily use after detection of 17p deletion is confirmed through the use of the FDA-approved companion diagnostic Vysis CLL FISH probe kit.
The most common side effects of Venclexta include neutropenia, diarrhoea, nausea, anaemia, upper respiratory tract infection, thrombocytopaenia and fatigue. Serious complications can include pneumonia, neutropenia with fever, fever, autoimmune hemolytic anaemia, anaemia and metabolic abnormalities known as tumour lysis syndrome. Live attenuated vaccines should not be given to patients taking Venclexta.
The FDA granted the Venclexta application breakthrough therapy designation, priority review status, and accelerated approval for this indication. These are distinct programmes intended to facilitate and expedite the development and review of certain new drugs in light of their potential to benefit patients with serious or life-threatening conditions. Venclexta also received orphan drug designation, which provides incentives such as tax credits, user fee waivers and eligibility for exclusivity to assist and encourage the development of drugs for rare diseases.
Venclexta is manufactured by AbbVie Inc. of North Chicago, Illinois, and marketed by AbbVie and Genentech USA Inc. of South San Francisco, California.
The Vysis CLL FISH probe kit is manufactured by Abbott Molecular of Des Plaines, Illinois.
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