Rusfertide: Research & Studies

Research Overview#

Rusfertide (PTG-300) has been evaluated in a structured clinical development program for polycythemia vera, progressing from phase 1 healthy volunteer studies through the phase 2 REVIVE trial (published in NEJM) to the ongoing phase 3 VERIFY trial. The evidence demonstrates consistent efficacy in controlling erythrocytosis through a novel mechanism-based approach targeting iron metabolism.

The evidence level is classified as moderate based on positive phase 2 results published in a top-tier journal with a confirmatory phase 3 trial reporting positive topline results, though the phase 3 data have not yet been published in full peer-reviewed form.

REVIVE Trial (Phase 2)#

Kremyanskaya et al., NEJM 2024 (PMID 38381675)#

The REVIVE trial was an international, phase 2, two-part study conducted at 16 centers in the United States and India. It enrolled 70 adults with polycythemia vera who required phlebotomy (with or without cytoreductive therapy) to maintain hematocrit below 45%.

Part 1 (Dose-Finding, 28 weeks):

• Open-label, dose-finding period
• Starting dose: 20 mg SC weekly, titrated to maintain hematocrit <45%
• Mean final weekly dose: 41.3 mg

Key Part 1 results:

• Estimated mean phlebotomies per year decreased from 8.7 before treatment to 0.6 during Part 1
• Mean maximum hematocrit decreased from 50.0% to 44.5%
• Improvement in symptom scores on the MPN-SAF for fatigue and pruritus

Part 2 (Randomized Withdrawal, 12 weeks):

• 59 patients randomized 1:1 to rusfertide (n=30) or placebo (n=29)
• Primary endpoint: composite response (hematocrit control, absence of phlebotomy, completion of trial regimen)

Key Part 2 results:

• Response rate: 60% rusfertide vs 17% placebo (P=0.002)
• Hematocrit control maintained in rusfertide group; lost in placebo group

Safety in REVIVE#

• Grade 3 adverse events: 13% of patients
• No grade 4 or 5 adverse events
• Injection site reactions: most common adverse event, grade 1-2 severity
• No serious adverse events attributed to rusfertide

VERIFY Trial (Phase 3)#

The VERIFY trial (NCT05210790) is a randomized, double-blind, placebo-controlled phase 3 study evaluating rusfertide in phlebotomy-dependent PV patients.

Topline Results (2025)#

• Primary endpoint met: 77% clinical response with rusfertide vs 33% placebo during weeks 20-32 (P<0.0001)
• All 4 key secondary endpoints met with statistical significance:
  • Hematocrit control
  • Patient-reported outcomes (PROMIS Fatigue SF-8a)
  • MPN symptom assessment (MFSAF TSS-74)
• Safety: Well tolerated; most adverse events were grade 1-2 injection site reactions; no new safety signals; all serious adverse events deemed unrelated to rusfertide

Two-Year Follow-Up Data#

Extended follow-up from the REVIVE study presented at ASH demonstrated:

• Durable hematocrit control over 2 years of continued treatment
• Sustained reduction in phlebotomy requirements
• Injection site reactions decreased from week 32 to 52, suggesting improvement over time
• No new safety concerns with extended use

Evidence Quality Assessment#

Key Research Gaps#

1. Long-term outcomes: Effect on thrombotic event rates and overall survival in PV, which require longer follow-up than currently available.

2. Comparative trials: No head-to-head comparison with ruxolitinib or other cytoreductive agents for hematocrit control.

3. Combination optimization: Optimal integration with hydroxyurea, ruxolitinib, or interferon in multimodal PV management.

4. Other iron-excess conditions: Early-stage investigation in hereditary hemochromatosis and beta-thalassemia could expand the therapeutic scope.

5. Biomarkers for response: Whether baseline iron parameters, JAK2 allele burden, or other markers predict response to rusfertide.

Related Reading#

• Rusfertide overview and research guide
• Rusfertide dosing protocols
• Rusfertide molecular structure