US FDA flagged issues in critical Tavneos trials, leading to Health Canada to advise doctors to halt starting the medication.
The warning issued after the FDA found data irregularities.
A medical journal has withdrawn a paper that used the trial data, saying the numbers were unreliable.
The New England Journal of Medicine has also withdrawn pivotal results from studies linked to Tavneos.
Regulators in both countries are reviewing the drug's safety and efficacy.
Amgen has still commented, leaving the issue unresolved.
The developments trigger concerns for patients as of now receiving the treatment.