Handok 'Vonjo' for severe myelofibrosis gets conditional approval

The Central Pharmaceutical Affairs Council (CPAC), ​"Clinical benefits outweigh risks"

No treatment option was available for patients with platelet counts below 50,000/µL

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A new treatment option is available in South Korea for patients with severe myelofibrosis who previously had no therapeutic options.

The Ministry of Food and Drug Safety (MFDS) approved marketing authorization on the 13th for Handok's orphan drug 'Vonjo Cap (active ingredient: pacritinib citrate),' under the condition of post-approval submission of confirmatory Phase 3 clinical trial data.

​According to a recently disclosed meeting summary from the Central Pharmaceutical Affairs Council (CPAC), strong unmet clinical demand, centered on the need to promptly provide treatment access to high-risk rare disease patients lacking alternative therapies, played a role in Vonjo's approval.

​Handok, partners with Sweden's Sobi for exclusive domestic supply

​Vonjo is an oral JAK2/IRAK1 inhibitor originally developed by US-based CTI BioPharma. Swedish Orphan Biovitrum (Sobi), a global biopharmaceutical company focused on rare diseases, later acquired CTI BioPharma to secure commercial rights. Through its partnership with Sobi, Handok has spearheaded the regulatory filing, distribution, and supply of Vonjo in South Korea.

The MFDS also recognized the drug's innovativeness and clinical urgency, designating it as the 32nd product under the "Global Innovative products on Fast Track (GIFT)" program. The MFDS supported rapid entry into domestic clinical practice through expedited review.

​Myelofibrosis is a rare hematologic malignancy characterized by bone marrow fibrosis that impairs normal hematopoiesis, resulting in splenomegaly, anemia, fatigue, and severe constitutional symptoms. The total domestic patient population in South Korea is estimated at approximately 2,200 to 2,300 individuals.

Conventional first- and second-line treatments have widely included JAK inhibitors such as Jakavi (ruxolitinib) and Inrebic (fedratinib). However, because these agents can induce thrombocytopenia via myelosuppressive mechanisms, they have a critical limitation, as dose reduction or treatment discontinuation is required whenever platelet counts drop below 50,000/µL.  

​In the CPAC meeting summaries, experts noted, "Although patients with platelet counts below 50,000/µL account for approximately 10% of the overall patient population, their survival risk from the underlying disease itself is exceptionally high," and pointed out, "Discontinuing existing therapies causes rapid disease progression, yet there were no alternative therapies available, creating a severe treatment blind spot." Approved agents targeting anemia were also evaluated as insufficient to overcome treatment limitations in patients with severe thrombocytopenia.

​"Clinical benefits outweigh risks"… Conditional approval granted pending Phase 3 data

​Vonjo is the first therapeutic engineered to be administered without dose reduction even in severe patients with platelet counts below 50,000/µL. The US National Comprehensive Cancer Network (NCCN) guidelines also recommend pacritinib for this patient population.

​According to the CPAC meeting summaries, key endpoint data on spleen volume reduction (a reduction of 35% or greater, SVR35) was heavily discussed. Spleen volume reduction serves as a core clinical metric that not only directly improves patient quality of life (relieving abdominal distension, digestive discomfort, and pain) but is also correlated with improved overall survival.  

​Committee members noted that because the submitted efficacy data were analyzed based on a patient cohort smaller than the initially planned sample size, there were limitations in statistical and confirmatory interpretation. However, the data showed a clear trend of clinical improvement, particularly in the 200 mg BID (twice daily) cohort, and the drug was highly evaluated for offering meaningful clinical benefits to both transplant-ineligible patients and patients awaiting hematopoietic stem cell transplantation (HSCT).

​Ultimately, the CPAC members unanimously concluded that "the clinical benefits outweigh the risks, and granting conditional approval subject to the post-marketing submission of results from ongoing global and domestic confirmatory Phase 3 clinical trials (such as PACIFICA) is justified."

​Given that the drug targets a high-risk patient population, committee members requested that the Risk Management Plan (RMP) and product labeling clearly outline baseline assessments before administration and detailed adverse reaction monitoring guidelines.

​Analysis suggests that this conditional approval is opening a new opportunity for life extension for severe myelofibrosis patients in South Korea who presented with baseline cytopenias/low platelet counts from initial diagnosis or were forced to discontinue treatment due to treatment-emergent thrombocytopenia under conventional therapies.