Primary Myelofibrosis Medical Services in China

Primary Myelofibrosis (PMF) is a rare, chronic Philadelphia chromosome-negative myeloproliferative neoplasm characterized by clonal proliferation of abnormal hematopoietic stem cells, progressive bone marrow fibrosis, extramedullary hematopoiesis (especially in the spleen and liver), and cytopenias. Unlike secondary myelofibrosis—which arises from other underlying conditions such as polycythemia vera or essential thrombocythemia—PMF originates de novo, with hallmark driver mutations in JAK2 (≈50–60%), CALR (≈25–35%), or MPL (≈5–10%). These mutations constitutively activate the JAK-STAT signaling pathway, leading to dysregulated cytokine production, aberrant megakaryocyte differentiation, and release of fibrogenic growth factors (e.g., TGF-β, PDGF) that stimulate reticulin and collagen deposition by bone marrow stromal cells. Over time, this fibrotic remodeling impairs normal hematopoiesis, resulting in anemia, thrombocytopenia, leukoerythroblastic peripheral blood smear, splenomegaly, and constitutional symptoms including fatigue, night sweats, weight loss, fever, and early satiety. Epidemiologically, PMF affects approximately 0.5–1.5 per 100,000 individuals annually, with median age at diagnosis around 65 years; it is slightly more common in males and shows no strong ethnic predilection. Risk factors include advancing age, presence of high-risk somatic mutations (e.g., ASXL1, SRSF2, IDH1/2, U2AF1), unfavorable karyotype (e.g., complex or monosomal abnormalities), severe anemia (hemoglobin <10 g/dL), leukocytosis >25 × 10⁹/L, circulating blasts ≥1%, and transfusion dependence. Quality of life is profoundly impacted: patients frequently experience debilitating fatigue, pain from massive splenomegaly, pruritus, cachexia, and anxiety related to disease progression and risk of transformation to acute myeloid leukemia (AML)—which occurs in 10–20% of cases over 10 years. Symptom burden correlates poorly with traditional lab parameters, underscoring the importance of patient-reported outcomes in clinical assessment. Management focuses on risk-adapted strategies: low-risk patients may require only observation or supportive care (e.g., erythropoiesis-stimulating agents, transfusions, hydroxyurea for splenomegaly control), while intermediate- and high-risk patients benefit from JAK inhibitors (ruxolitinib, fedratinib, pacritinib) to alleviate symptoms and reduce splenomegaly. Allogeneic hematopoietic stem cell transplantation remains the only potentially curative option—but is limited to fit patients under age 70 with suitable donors due to significant morbidity and mortality. Ongoing research explores combination therapies, novel antifibrotic agents, and immunomodulatory approaches to modify disease biology.

Primary myelofibrosis (PMF) is a rare, clonal myeloproliferative neoplasm characterized by bone marrow fibrosis, extramedullary hematopoiesis (predominantly in the spleen and liver), progressive cytopenias, constitutional symptoms, and risk of leukemic transformation. Management is individualized based on disease risk stratification (e.g., DIPSS-plus: Dynamic International Prognostic Scoring System–plus), symptom burden, age, comorbidities, and transplant eligibility. Treatment goals include alleviating symptoms, correcting cytopenias, reducing splenomegaly, delaying disease progression, and improving overall survival—particularly through allogeneic hematopoietic stem cell transplantation (allo-HSCT) in eligible patients.

Conservative treatment forms the cornerstone for low- and intermediate-1–risk patients without significant symptoms or cytopenias. This includes regular clinical and laboratory monitoring (CBC, peripheral blood smear, LDH, uric acid, serum ferritin, and periodic bone marrow biopsy with cytogenetics and molecular profiling—including JAK2 V617F, CALR, and MPL mutations). Supportive care is essential: red blood cell transfusions for symptomatic anemia (with iron chelation therapy if ferritin exceeds 1,000 ng/mL after ≥30 units); platelet transfusions for severe thrombocytopenia with bleeding; and prophylactic anticoagulation in high-risk thrombotic settings (e.g., prior thrombosis, JAK2-mutated disease, or immobilization). Nutritional support, fatigue management, and psychosocial counseling are integral to maintaining quality of life. Splenic radiation may be considered for palliation of painful splenomegaly when pharmacologic options fail or are contraindicated, though effects are transient and carry risks of cytopenias and secondary malignancy.

Pharmacotherapy targets both disease biology and symptom control. Ruxolitinib—a first-generation JAK1/JAK2 inhibitor—is FDA- and NMPA-approved for intermediate- or high-risk PMF and has demonstrated durable reductions in spleen volume (≥35% in ~40% of patients at 24 weeks), improvement in constitutional symptoms (e.g., night sweats, weight loss, pruritus), and potential survival benefit versus best available therapy. Fedratinib and pacritinib are alternative JAK inhibitors approved for ruxolitinib-intolerant or thrombocytopenic patients (platelet count <50 × 10⁹/L), respectively. Novel agents under investigation include momelotinib (JAK1/2 and ACVR1 inhibitor, approved for anemia-associated PMF), navitoclax (BCL-2/BCL-xL inhibitor in combination with ruxolitinib), and pelabresib (a BET inhibitor showing synergistic activity in phase III trials). Immunomodulatory agents (e.g., thalidomide ± prednisone or lenalidomide ± prednisone) may improve anemia in select patients but carry significant toxicity (neuropathy, venous thromboembolism, myelosuppression). Hydroxyurea remains useful for controlling marked leukocytosis or thrombocytosis but lacks impact on fibrosis or survival. Interferon-alpha (pegylated formulations preferred) may induce molecular responses in early-stage disease but is limited by tolerability.

Surgical treatment is largely restricted to splenectomy in highly selected cases—typically for massive, symptomatic splenomegaly refractory to medical therapy, severe cytopenias due to hypersplenism, or portal hypertension complications. Preoperative optimization includes vaccination (pneumococcal, meningococcal, Haemophilus influenzae type B), platelet transfusion support, and bridging anticoagulation. Laparoscopic approaches are increasingly utilized in experienced centers to reduce morbidity. However, splenectomy carries substantial perioperative risks: bleeding (especially with platelet dysfunction), infection (overwhelming post-splenectomy infection), thrombosis (splanchnic vein thrombosis in up to 20%), and accelerated disease progression. It is generally avoided in high-risk patients or those with marked leukocytosis (>25 × 10⁹/L) or circulating blasts >1%. Allo-HSCT remains the only potentially curative modality and is recommended for fit patients ≤70 years with intermediate-2 or high-risk DIPSS-plus scores. Reduced-intensity conditioning regimens have expanded eligibility, with 5-year overall survival rates of 40–60% and progression-free survival of 35–50%. Outcomes depend heavily on donor match, disease burden pre-transplant, and center expertise.

China offers distinct advantages in PMF management. First, rapid access to novel therapeutics: ruxolitinib received NMPA approval in 2017 and is widely available through national reimbursement programs, significantly lowering out-of-pocket costs. Second, China hosts several world-class transplant centers (e.g., Peking University People’s Hospital, Institute of Hematology & Blood Diseases Hospital in Tianjin) performing >1,000 allo-HSCTs annually for myeloid malignancies, with robust infrastructure for HLA typing, graft-versus-host disease (GVHD) prophylaxis (including post-transplant cyclophosphamide), and supportive care. Third, integration of traditional Chinese medicine (TCM) as adjunctive therapy—under rigorous hematologic supervision—has shown promise in ameliorating fatigue, improving appetite, and stabilizing hemoglobin in observational studies, though randomized data remain limited. Fourth, centralized biobanking and genomic profiling initiatives (e.g., China Kadoorie Biobank, Shanghai Blood Center’s MPN registry) facilitate real-world evidence generation and clinical trial enrollment. Finally, multidisciplinary ‘MPN clinics’—staffed by hematologists, transplant physicians, radiologists, pathologists, and palliative care specialists—are increasingly standard in tier-3 hospitals, ensuring coordinated, guideline-concordant care.

Recovery and long-term management emphasize patient empowerment and proactive surveillance. Patients should maintain a symptom diary tracking fatigue, night sweats, abdominal discomfort, bleeding episodes, and medication side effects. Regular follow-up every 3–6 months includes CBC, comprehensive metabolic panel, LDH, and physical exam with spleen measurement. Annual bone marrow evaluation is advised for patients with worsening cytopenias, rising blast percentage, or new cytogenetic abnormalities. Lifestyle modifications include avoiding NSAIDs (due to bleeding risk), using sun protection (JAK inhibitors increase non-melanoma skin cancer risk), engaging in moderate aerobic activity to combat fatigue, and adhering strictly to vaccination schedules (including annual influenza and COVID-19 boosters). Genetic counseling is recommended for first-degree relatives given the low but measurable familial clustering. Psychosocial support—including peer networks facilitated by organizations like the China Myeloproliferative Neoplasm Alliance—is vital for coping with chronic illness uncertainty. Ultimately, optimal PMF care requires balancing disease-modifying interventions with personalized supportive strategies, continuous risk reassessment, and shared decision-making grounded in evolving evidence.