Omjjara effective for high-risk myelofibrosis… access should be expanded

Shows strength in anemia improvement… expectations also rising for platelet recovery

Survival period for intermediate/high-risk groups only 2-3 years…“Treatment options must be secured”

“High-risk myelofibrosis patients with cytopenia have a clear unmet need due to the lack of appropriate treatment options. Omjjara is an option for these patients. This is why its reimbursement coverage is necessary.”

Professor Sung-Eun Lee, Department of Hematology,  Seoul St. Mary’s Hospital

Professor Sung-Eun Lee of the Department of Hematology at Seoul St. Mary’s Hospital emphasized the unmet needs in the myelofibrosis treatment landscape and the necessity of improving access to new therapies in a recent interview with DailyPharm.

Myelofibrosis is a rare hematologic malignancy belonging to the chronic myeloproliferative neoplasm and is considered the most clinically severe condition within this group. Chronic myeloproliferative neoplasms are categorized based on the presence or absence of chromosomal abnormalities. Philadelphia chromosome–negative polycythemia vera and essential thrombocythemia generally show relatively slow progression.

However, approximately 20% of patients with these conditions may progress to myelofibrosis and secondary acute leukemia over time, at which point the prognosis deteriorates rapidly.

One of the most critical prognostic factors is hemoglobin level. Myelofibrosis is a disease where the bone marrow, the body's blood cell factory, is gradually replaced by fibrotic substances like collagen or reticulin, leading to a decline in normal hematopoietic function. As a result, blood cell production and maturation are disrupted, causing anemia.

When anemia is present, the patient's quality of life significantly declines. Reports indicate that myelofibrosis patients with anemia have a survival rate approximately 3 to 4 times lower than those without anemia. For this reason, managing anemia is a major therapeutic goal in myelofibrosis treatment.

In September last year, GSK’s Omjjara (momelotinib) received approval from the Ministry of Food and Drug Safety for the treatment of adult patients with intermediate- or high-risk myelofibrosis with anemia (including primary myelofibrosis, post–polycythemia vera myelofibrosis, and post–essential thrombocythemia myelofibrosis), thereby expanding treatment options.

Omjjara differentiates itself through a unique mechanism of action. In addition to inhibiting JAK1 and JAK2 like conventional JAK inhibitors, it also inhibits ACVR1. This novel approach normalizes iron metabolism through suppression of hepcidin overexpression, a key cause of anemia.

The introduction of Omjjara is expected to reshape myelofibrosis treatment strategies. However, as reimbursement coverage has not yet been granted, access to the drug remains limited for transfusion-dependent myelofibrosis patients in Korea.

Professor Lee stressed the need to improve access to new treatments, emphasizing that myelofibrosis is a disease where patients can maintain social and daily life while undergoing treatment, and thus should not be restricted in all aspects of life.

Q. Myelofibrosis is a relatively unknown rare blood cancer. Could you introduce the disease?

Myelofibrosis is a disease closely associated with molecular genetic abnormalities, most commonly involving JAK2, CALR, and MPL mutations. JAK2 mutations are most frequent, followed by CALR and MPL mutations. Prognosis varies depending on the mutation type. Patients with CALR mutations generally have a relatively favorable prognosis, while so-called “triple-negative” patients are known to have the poorest prognosis. However, current clinical practice does not differentiate treatment strategies based on mutation subtypes.

This disease presents with distinct symptoms and significantly impairs patients' quality of life. The course varies greatly depending on the patient's risk group and disease stage. As it is a functional disorder, there is currently no treatment that fundamentally halts disease progression. Therefore, selecting the appropriate treatment strategy based on patient status and risk assessment is critical.

Median survival for intermediate- and high-risk patients is only 2 to 3 years, whereas early-stage patients may survive for more than 7 to 8 years. However, many patients are diagnosed only after symptoms develop, meaning many patients are already in the intermediate or high-risk group at diagnosis. In particular, patients with marked cytosis or the presence of blasts tend to show rapid disease progression.

Q. How is myelofibrosis currently treated?

The only curative treatment for myelofibrosis is hematopoietic stem cell transplantation. However, myelofibrosis predominantly affects elderly patients and is often accompanied by comorbidities, resulting in poorer post-transplant outcomes compared to other acute hematologic malignancies. Therefore, transplant candidates are selected very carefully based on age, general condition, comorbidities, performance status, and donor availability.

For patients ineligible for transplantation, the primary treatment goals are to reduce splenomegaly and alleviate systemic symptoms. In this setting, JAK-STAT pathway inhibitors such as Omjjara, ruxolitinib, and fedratinib are used, each with distinct efficacy and characteristics. Because symptoms and clinical characteristics vary among patients, drug selection is personalized for each individual patient.

Furthermore, securing a donor and improving the patient's overall condition prior to transplantation often requires a certain amount of time. During this period, drug therapy serves as a bridge to maintain the patient's condition in a stable state until transplantation.

Q. What are the unmet needs in the current myelofibrosis treatment landscape?

Historically, treatment options were limited for myelofibrosis. Ruxolitinib was effectively the only first-line therapy, followed by fedratinib. However, both drugs are difficult to use in patients with severe anemia or platelet counts below 50,000/µL.

Anemia, in particular, has a profound impact on quality of life. Transfusion-dependent patients often require one or two units of blood per month and must spend 4–5 hours at the hospital for each transfusion. As the transfusion date approaches, systemic fatigue and weakness from anemia make mobility difficult. Patients often experience a pattern where daily functioning temporarily improves immediately after a transfusion, only to deteriorate again.

When adverse reactions occur during treatment or the effect is insufficient, switching medications is necessary, but the limited alternatives have also been a major challenge in clinical practice. Consequently, patients who failed existing treatments or required additional therapy often had no options other than participating in clinical trials.

Q. Omjjara was approved in Korea last September. Could you explain the clinical evidence supporting its approval?

Unlike existing therapies, Omjjara has a mechanism of action that is favorable for anemia improvement and was therefore developed and approved specifically for myelofibrosis patients with cytopenia, an area with the greatest unmet need. Clinically, it can also be considered a treatment option for patients with severe thrombocytopenia, and improvements in anemia indicators are being observed in actual clinical practice.

The SIMPLIFY-1 trial directly compared Omjjara with ruxolitinib and demonstrated non-inferiority in key endpoints such as spleen volume reduction. It also demonstrated clinically meaningful results in anemia-related parameters, providing the basis for the subsequent MOMENTUM study, which focused on anemia improvement and reduction in transfusion dependency.

From a safety perspective, no new adverse effects of significant concern were identified compared to previous trials. While caution is required for infection management as with all JAK inhibitors, this falls within the familiar domain of healthcare providers treating hematologic malignancies and is deemed manageable in routine clinical practice.

Q. Could you share any memorable patient cases or instances where notable changes occurred after using Omjjara?

In Korea, experience with Omjjara has been accumulated through the Expanded Access Program (EAP), both as an initial treatment option or subsequent therapy after existing treatments in patients with myelofibrosis accompanied by anemia.

Omjjara has also been used as a bridging therapy maintain stable conditions in patients awaiting hematopoietic stem cell transplantation. In one case, a patient with a baseline hemoglobin level below 8 g/dL and high transfusion requirements achieved recovery to approximately 11 g/dL after starting Omjjara. Furthermore, Omjjara is also being considered as an important treatment option for elderly patients for whom transplantation is difficult and who require long-term disease management.

Q. What recommendations would you make to improve treatment access for myelofibrosis patients?

Although myelofibrosis is a rare disease with a small patient population, unmet medical needs are substantial in clinical practice. In Korea, issues affecting large populations tend to receive more attention, while the voices of patients with rare, severe diseases are often overlooked. Consequently, the rarer and intractable the disease, the harder it is to secure reimbursement for new treatments.

However, the unmet need is clear for high-risk myelofibrosis patients with cytopenia, as they lack appropriate treatment options. Furthermore, even intermediate-risk patients may experience changes in the clinical characteristics of their disease, making it crucial to secure multiple treatment options.

Omjjara has accumulated robust clinical data in these patient populations. If reimbursement coverage is granted, patients who were previously constrained by repeated transfusions may be able to continue treatment more stably and return to daily life. Since myelofibrosis is a disease that allows patients to maintain social and daily activities while undergoing treatment, improving access to treatment will help ensure that patients are not forced to limit every aspect of their lives because of the disease itself.

Currently, some patients continue Omjjara treatment through expanded access programs or at their own expense. Given the unmet needs in clinical practice, it is hoped that an environment will be established in which Omjjara can be introduced for more patients at the appropriate time.