Pacritinib Added to NCCN Recommendation for Treatment in MPNs

The novel kinase inhibitor pacritinib (Vonjo) was added to the latest National Comprehensive Cancer Network (NCCN) guidelines as a recommended treatment for patients with myeloproliferative neoplasms (MPN), according to a press release.¹

"We are grateful that the NCCN acted quickly to include (pacritinib) with a Category 2A designation in its Clinical Practice Guidelines in Oncology as a first line treatment for high-risk patients with myelofibrosis with platelet counts less than 50 x 109/L who are not candidates for transplant,” said Adam R. Craig, MD, PhD, president, and chief executive officer of CTI BioPharma, in a statement. “This therapeutic option helps address an unmet medical need for patients who previously have no other treatment options. There is no other FDA-approved first line treatment for these patients with a 2A designation within the NCCN guidelines.”

Pacritinib was approved by the FDA earlier this year for the treatment of patients with myelofibrosis and severe thrombocytopenia, defined as a platelet count less than 50x10⁹/L. In addition to this designation from the FDA, the NCCN has recommended pacritinib as a second-line treatment in low-risk and high-risk patients with myelofibrosis who have a platelet count greater than 50 x 10⁹/L who are also not candidates for transplant. According to Craig, this will allow for even more treatment options in patients with MPNs.

The JAK family of enzymes promotes normal blood cell growth in patients because JAK is central component in signal transaction pathways, meaning that there is a direct relationship between mutations in these pathways and the development of hematological cancers like MPNs. Thus, allowing pacritinib to impact the development of the disease.

“In the US, there are approximately 21,000 patients with myelofibrosis, two-thirds of which have cytopenias (thrombocytopenia or anemia), commonly resulting from the toxicity of other approved therapies,” Craig said in a press release when announcing the FDA approval of pacritinib.² “Severe thrombocytopenia, defined as a blood platelet count below 50 × 109/L, occurs in one-third of the overall myelofibrosis population, and has a particularly poor prognosis.”

Results from the phase 3 PERSIST-1 (NCT01773187), phase 3 PERSIST-2 (NCT02055781), and phase2 dose-finding PAC203 trial led to the initial approval, and now recommendation by the NCCN, for the use of pacritinib in multiple lines of therapy for patients with MPNs. These findings demonstrated that the kinase inhibitor, with specificity for inhibiting JAK2 and IRAK1 without inhibiting JAK1, was associated with better outcomes in patients in comparison to the best available therapy.

After the PERSIST-1 trial met its primary endpoint at week 24 of the study when 19% of patients on pacritinib had a spleen reduction size by 35% or more compared to 5% in the control group, 311 patients enrolled in the PERSIST-2 trial saw better results on pacritinib given twice a day.³ Eighteen percent of patients in the twice daily pacritinib arm of the trial had a spleen reduction of 35% or greater vs 3% in the best available therapy arm.⁴

The most common adverse events (AEs) observed on twice-daily pacritinib at 200 mg, seen in 20% or more of paitents, was diarrhea, thrombocytopenia, nausea, anemia and peripheral edema. Serious AEs seen in 3% or more of patients on the same regimen were anemia, thrombocytopenia, pneumonia, cardiac failure, disease progression, pyrexia, and squamous cell carcinoma of skin.

“The approval of pacritinib establishes a new standard of care for myelofibrosis patients suffering from cytopenic myelofibrosis," said John Mascarenhas, MD, associate professor, Medicine, Hematology and Medical Oncology, Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, New York, in a press release on the approval of the drug. "Myelofibrosis with severe thrombocytopenia, defined as blood platelet counts below 50 × 109/L, has been shown to result in poor survival outcomes coupled with debilitating symptoms. Limited treatment options have rendered this disease an area of urgent unmet medical need."

_References

_{1. NCCN Guidelines® Recommend VONJO™ (pacritinib) for the Treatment of Myeloproliferative Neoplasms. CTI BioPharma Corp. News release. April 14, 2022. Accessed April 14, 2022. https://prn.to/3EiDaN0}

_{2. CTI BioPharma announces FDA accelerated approval of VONJO™ (pacritinib) for the treatment of adult patients with myelofibrosis and thrombocytopenia. CTI BioPharma Corp. News release. February 28, 2022. Accessed April 14, 2022. https://bit.ly/3vsDPsO}

_{3. Mesa R, Vannuchhi A, Mead A, et al. Pacritinib versus best available therapy for the treatment of myelofibrosis irrespective of baseline cytopenias (PERSIST-1): an international, randomised, phase 3 trial. The Lan. Hem. Published: March 20, 2017. doi: https://doi.org/10.1016/S2352-3026(17)30027-3}

_{4. Mascarenhas J, Hoffman R, Talpaz M, et al. Pacritinib vs Best Available Therapy, Including Ruxolitinib, in Patients With Myelofibrosis: A Randomized Clinical Trial. JAMA Oncol. 2018;4(5):652–659. doi:10.1001/jamaoncol.2017.5818}