Redx Pharma PLC said it was pausing patient enrollment in an early stage clinical trial of its drug RXC004.
The U.K.-based pharmaceutical company's decision is based on the "clinically significant adverse events" observed in the first patient dosed in the phase 1/2a clinical study, which was designed to establish the safety and tolerability of the drug.
The company did not elaborate on the adverse events but said it believed they were related to the drug. It is in discussions with the U.K.'s Medicines and Healthcare products Regulatory Agency to amend the study's parameters so patients start at lower doses.
The company expects to enroll a total of 50 patients in the study.
Shares of the company dropped about 69% on the news to 4 pence each as of market close March 29, 2018.
"While we remain confident that we can address this issue, we currently estimate that this suspension will lead to a delay of several months. The board continues to believe it has sufficient resources to continue to progress RXC004 and its broader portfolio of oncology and fibrosis assets," Redx Executive Chairman Iain Ross said in a statement.
RXC004 targets the Wnt pathway in the body, which is responsible for cancer growth. It is being developed for patients with advanced tumor forms.