Shares in Mirati plummet after disappointing Phase II trial

Shares in the California-based biotech Mirati Therapuetics plummeted on Monday after the company released disappointing results from their Phase II study of the experimental drug sitravatinib, for use in combination with Bristol-Myers Squibb’s Opdivo for treatment of patients with non-small-cell lung cancer (NSCLC) patients with documented progression on prior immune checkpoint inhibitor therapy.

Stock prices fell from $40 to $30 a share on Monday morning after it was revealed that just nine of 56 patients had a confirmed partial or complete response. Mirati stocks are currently trading at around $34 a share.

On top of the nine patients with confirmed partial or complete responses, two patients had unconfirmed partial or complete responses, while five others had unconfirmed responses "that will not be confirmed".

However it was noted that 18 of the 56 patients evaluated demonstrated tumour reductions greater than 30%.

Dr Ticiana Leal, Assistant Professor of Medicine, Thoracic Oncology Program Leader at the University of Wisconsin commented: "To date, the combination of sitravatinib and nivolumab has demonstrated a significant number of durable responses in patients with advanced NSCLC who experienced disease progression following prior checkpoint inhibitor therapy, which is one of the most challenging clinical scenarios that we currently face for this patient population. The results of the study are encouraging as it continues to show a clinical benefit for these patients and has a favourable safety profile."