The Food and Drug Adninistration ( FDA ) has granted accelerated approval for Vonjo ( Pacritinib ) capsules to treat adults who have a rare form of a bone marrow disorder known as intermediate or high-risk primary or secondary myelofibrosis and who have platelet levels below 50,000/µL.
Myelofibrosis is a rare bone marrow disorder that disrupts blood cell production. It causes extensive bone marrow scarring, which can lead to severe anemia. This scarring can also reduce the number of platelets, which increases the risk of bleeding.
The disease often causes an enlarged spleen, the organ that filters red blood cells.
Myelofibrosis can occur on its own ( primary disease ) or it can develop from another bone marrow disorder ( secondary disease ).
The effectiveness and safety of Vonjo were demonstrated in a study that included 63 patients with intermediate or high-risk primary or secondary myelofibrosis and low platelets who received Vonjo 200 mg twice daily or standard treatment.
Effectiveness was determined based upon the proportion of patients who had a 35% or greater spleen volume reduction from baseline to week 24.
Nine patients ( 29% ) in the Vonjo treatment group had a 35% or greater spleen volume reduction, compared to one patient ( 3% ) in the standard treatment group.
As a condition of the accelerated approval, an ongoing study of Vonjo must be completed to confirm that spleen volume reduction leads to clinical benefit, such as an improvement in how patients with myelofibrosis feel or function.
Patients must not use Vonjo if they are also taking certain other medicines, such as strong CYP3A4 inhibitors or inducers.
Common side effects include diarrhea, low platelet counts, nausea, anemia, and swelling in legs.
Because of the risk of major bleeding, patients with active bleeding ( blood loss that is quick and difficult to control ) should avoid taking Vonjo, and patients should stop Vonjo seven days before any planned surgery.
Patients who have bleeding while on Vonjo may need to pause or stop taking the medication, depending on the severity.
Another JAK-inhibitor ( Tofacitinib ) has increased the risk of major adverse cardiac events ( such as death, myocardial infaction and stroke ) and cancer, particularly in patients with certain risk factors, as well as thrombosis.
Infections can also occur in patients treated with Vonjo. Patients with symptoms of these conditions should be promptly evaluated and treated. Patients should delay starting Vonjo until active serious infections have resolved. ( Xagena )
Source: FDA, 2022