Refined iRRF6 Model for Myelofibrosis Risk Stratification
- A new model, called the intermediate-1 Risk Response 6 (iRR6), has been developed to more accurately identify myelofibrosis (MF) patients at intermediate-1 risk who may benefit from adjustments...
- The original RR6 model was effective in identifying patients likely to have poor long-term outcomes, but it wasn't as useful for lower-risk patients.
- Researchers developed the iRR6 model by adding three new prognostic variables to the existing RR6 framework:
New iRR6 Model Improves Risk Stratification in Myelofibrosis Patients Treated with Ruxolitinib
A new model, called the intermediate-1 Risk Response 6 (iRR6), has been developed to more accurately identify myelofibrosis (MF) patients at intermediate-1 risk who may benefit from adjustments to their ruxolitinib treatment. This model is a subanalysis of the large RUX-MF study and builds upon the previously established “response to ruxolitinib after six months (RR6)” score.
The Problem with the Existing Model:
The original RR6 model was effective in identifying patients likely to have poor long-term outcomes, but it wasn’t as useful for lower-risk patients. Specifically, in a study of 428 intermediate-1 patients, the RR6 model didn’t effectively differentiate between intermediate and low-risk groups (5-year overall survival (OS) of 74.4% vs.72.0%, P* = .24). Only the high-risk group within this cohort showed substantially poorer 5-year OS (57.4%, *P < .01).
The iRR6 Solution:
Researchers developed the iRR6 model by adding three new prognostic variables to the existing RR6 framework:
* Ruxolitinib Underdosing: Receiving a dose of ruxolitinib that is too low relative to the patient’s platelet count at one or more time points (HR, 3.91; P* < .001).
* Insufficient Spleen Reduction: Failing to achieve at least a 50% reduction in palpable spleen size at 6 months (HR, 1.45; *P = .02).
* Red Blood Cell Transfusion Requirement: Needing red blood cell transfusions consistently throughout treatment (HR,1.85; P* = .01).
iRR6 Scoring & Risk Categories:
Patients are scored based on these variables, falling into one of three risk categories:
* Low-Risk (Score 0): 5-year OS of 84.8% (20.3% of patients)
* Intermediate-risk (Score 1-2): 5-year OS of 76.4% (45.8% of patients)
* High-Risk (Score >2): 5-year OS of 56.6% (33.9% of patients) (P* < .0001)
Validation & Clinical Implications:
The iRR6 model was validated in an external cohort of 95 intermediate-1 risk patients at Moffitt Cancer Center, with similar results:
* Low-Risk: 83.3% 5-year OS
* Intermediate-Risk: 71.7% 5-year OS
* High-Risk: 54.5% 5-year OS (*P* =.01)
This new model is significant because it can help identify intermediate-1 risk patients who are unlikely to benefit from long-term ruxolitinib treatment and may be candidates for option therapies, including possibly allogeneic stem cell transplantation – a treatment often not considered for this risk group. The iRR6 provides a more precise tool for tailoring treatment strategies in MF patients.