Seattle Genetics Inc said the U.S. Food and Drug Administration lifted a clinical hold on several early stage studies testing its experimental cancer drug.

The FDA imposed the clinical hold in December after the company reported the deaths of four people in trials testing the experimental cancer drug, vadastuximab talirine.

Seattle Genetics said the clinical hold was resolved through a comprehensive study evaluating more than 300 patients and amendments to further enhance safety.

The company said it would resume two early-stage trials and initiate a mid-stage trial of vadastuximab talirine in 2017, in patients with acute myeloid leukemia (AML), a type of blood cancer.

The drug would continue to be tested in an ongoing late-stage study in older AML patients, the company said.

AML is a type of cancer in which the bone marrow makes abnormal myeloblasts (a type of white-blood cell), red blood cells, or platelets.

Vadastuximab talirine, which has an orphan drug status from both the USFDA and European regulators for the treatment of AML, is also being tested in patients with myelodysplastic syndrome, another form of blood cancer.

Last month, Seattle Genetics entered into a development and licensing deal worth up to $2 billion with Immunomedics Inc to bolster its cancer drug pipeline.

Up to Friday's close, Seattle Genetics' shares had risen about 15 percent since the deal with Immunomedics.