Merck's Zolinza clears phase III trial in multiple myeloma

Merck & Co's Zolinza has shown promise in a phase III trial involving multiple myeloma patients, potentially opening up a lucrative new market for the drug.

Zolinza (vorinostat) has faced several issues in its development. It won approval in 2006 in the US as a treatment for cutaneous T cell lymphoma (CTCL) - a form of non-Hodgkin's lymphoma that affects the skin - but Merck (known as MSD outside the US) failed to convince regulators in Europe of its benefits in this indication. Meanwhile, phase III trials of the drug in mesothelioma were also unsuccessful, although Merck is still carrying out other studies in this indication.

CTCL is a rare disease, making Zolinza a minor drug for Merck at the moment. It didn't feature in its quarterly financial breakdown of sales by product.

Multiple myeloma is potentially a much larger market for the drug, forecast to reach $6.4bn by 2017 thanks to increasing incidences of the disease worldwide; increased use of already-marketed drugs; and an expanding array of new treatments.

In the phase III trial, Zolinza given in combination with Takeda/Millennium Pharmaceuticals' Velcade (bortezomib) in patients with progressive multiple myeloma achieved a 23 per cent reduction in the risk of disease progression compared to Velcade plus placebo.

In addition to the improvement in progression-free survival, Zolinza achieved a significant improvement in overall response rate at 56 per cent compared to 41 per cent in the comparator group, and there was a trend towards improved overall survival.

"Most patients with multiple myeloma eventually relapse or become resistant to treatment," said Meletios Dimopoulos, of the University of Athens School of Medicine in Greece, one of the principle investigators in the trial.

"We are encouraged by the results of the investigational use of Zolinza in combination therapy in this difficult-to-treat patient population."

Approval of Zolinza as a combination regimen in multiple myeloma could have a dramatic effect on sales. Along with Celgene's Revlimid (lenalidomide) and Celgene/Fujimoto Seiyaku's Thalomid/Thaled (thalidomide), Velcade is one of the standard treatments for multiple myeloma, with annual sales of around $1.5bn at present, expected to rise to around $3bn in 2015.

Meanwhile, Zolinza is in clinical trials for a range of solid tumours, including brain, oropharyngeal, ovarian, liver, prostate and lung cancers, as well as non-Hodgkin's lymphoma, acute myeloid leukaemia and acute lymphoblastic leukaemia.