CancerConnect News: Jakafi® (ruxolitinib) was initially reported to help patients with polycythemia vera (PV) maintain hematocrit control more effectively than the best available therapy at the 56th American Hematology Society Annual Meeting in 2014.1,2 Now with a full 4 years of follow-up from this trial the benefit of Jakafi® continues to be confirmed. Results recently presented at the 59th American Society of Hematology (ASH) Annual Meeting 2017 in Atlanta, Georgia demonstrate that the effectiveness and safety of Jakafi used to treat PV patients who were resistant to or intolerant of hydroxyurea (HU) continue beyond 4 years of treatment and are consistent with the results initially reported.3
Polycythemia vera is a slow-growing type of blood cancer that belongs to a group of blood disorders called myeloproliferative neoplasms (MPN). In these disorders, the bone marrow cells that produce blood cells develop and function abnormally. In PV the bone marrow makes too many blood cells, particularly red blood cells. These excess cells thicken the blood and can cause complications, such as a risk of blood clots or bleeding. Without treatment, PV can be life threatening and can eventually progress to more serious blood cancers, such as myelofibrosis or acute leukemia. Effective treatment, however, can significantly decrease risks and complications.
The goal of treatment for PV is to reduce the thickness of the blood and prevent bleeding and clotting. Jakafi has proven effective in the treatment of PV, including in patients with intolerance or resistance to HU the most common first-line treatment for patients with high-risk PV. Jakafi works by inhibiting proteins that may play a role in the development of MPNs by causing the body to make the wrong number of blood cells (JAK1/JAK2 proteins).
The RESPONSE trial compared outcomes between Jakafi and best available therapy (BAT) in patients with PV who can’t tolerate Hydrea or are resistant to it. In the primary analysis of RESPONSE Jakafi more effectively improved clinical signs of disease (hematocrit control and at least a 35% reduction in spleen size) and symptoms in patients with PV. After eights months of study, patients on best available therapy who had not reached desired disease control were allowed to switch to treatment with Jakafi.4
At the week 208 analysis 37% of patients originally treated with Jakafi were still receiving therapy and no patients treated with best available therapy BAT remained on their treatment. Importantly 98 patients initially treated with BAT were allowed to “cross over” and receive Jakafi after week 32. Overall 38% of these patients responded to and remain on Jakafi.
This analysis of findings from the RESPONSE trial indicates that Jakafi more effectively helps patients with PV maintain long-term hematocrit control than best available therapy. As more study data is released, Jakafi appears increasingly promising in the treatment of PV. With this 30 months of additional follow-up, the four-year RESPONSE data further reinforces Jakafi as a standard long-term treatment for patients with PV.
About Jakafi® (ruxolitinib)
Jakafi is a first-in-class JAK1/JAK2 inhibitor approved by the U.S. Food and Drug Administration for treatment of people with polycythemia vera (PV) who have had an inadequate response to or are intolerant of hydroxyurea.
Jakafi is also indicated for treatment of people with intermediate or high-risk myelofibrosis (MF), including primary MF, post–polycythemia vera MF, and post–essential thrombocythemia MF.
 Verstovse S, Kiladjian J-J, Mesa R, et al. Ruxolitinib. Efficacy By Hematocrit Control in Patients with Polycythemia Vera: An Analysis of the RESPONSE Trial. Program and Abstracts of 56th American Hematological Society Annual Meeting and Exposition; December 6–9, 2014; San Francisco, California. Abstract 3201.
 Study of Efficacy and Safety in Polycythemia Vera Subjects Who Are Resistant to or Intolerant of Hydroxyurea: JAK Inhibitor INC424 (INCB018424) Tablets Versus Best Available Care: (The RESPONSE Trial) ((RESPONSE)). ClinicalTrials.gov website. Available at: http://clinicaltrials.gov/ct2/show/NCT01243944. Accessed December 6, 2014.
3. Kiladjian J, Verstovsek S, Griesshammer M, et al. Results From The 208-Week (4-year) Follow-Up Of RESPONSE Trial, A Phase 3 Study Comparing Ruxolitinib (Rux) With Best Available Therapy (BAT) For The Treatment Of Polycythemia Vera (PV). Abstract #322. 59th American Society of Hematology (ASH) Annual Meeting 2017, Atlanta, Georgia, USA.
4. Vannucchi AM, Kiladjian JJ, Griesshammer M, et al. Ruxolitinib versus standard therapy for the treatment of polycythemia vera. N Engl J Med. 2015;372(5):426-435.
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