The mpn Hub website uses a third-party service provided by Google that dynamically translates web content. Translations are machine generated, so may not be an exact or complete translation, and the mpn Hub cannot guarantee the accuracy of translated content. The mpn and its employees will not be liable for any direct, indirect, or consequential damages (even if foreseeable) resulting from use of the Google Translate feature. For further support with Google Translate, visit Google Translate Help.
The MPN Hub is an independent medical education platform, sponsored by AOP Health and GSK, and supported through an educational grant from Bristol Myers Squibb. The funders are allowed no direct influence on our content. The levels of sponsorship listed are reflective of the amount of funding given. View funders.
Now you can support HCPs in making informed decisions for their patients
Your contribution helps us continuously deliver expertly curated content to HCPs worldwide. You will also have the opportunity to make a content suggestion for consideration and receive updates on the impact contributions are making to our content.
Find out moreCreate an account and access these new features:
Bookmark content to read later
Select your specific areas of interest
View mpn content recommended for you
Pegylated interferon alfa-2 (PEG-IFN) induces high response rates in many patients with polycythemia vera (PV), while some patients do not respond well. In order to identify specific genetic predictors, a new study by Jaeger and colleagues in Blood investigated specific germline diplotypes of the interferon lambda 4 (IFNL4) gene locus and their correlation with PEG-IFN treatment outcome.1
Samples from 122 patients treated with PEG-IFN in the PROUD-PV and CONTINUATION-PV trials were used for the primary analysis, while samples from 27 patients treated in the PEGINVERA trial (NCT01193699) were used to replicate results.1,2 The samples were analyzed with Affymetrix SNP 6.0 microarrays at 12, 18, 24, 30, and 36 months of follow-up. IFNL4 variants were sequenced and phased with SHAPEIT.3
Using a genome-wide association study analysis tagging single nucleotide polymorphism (SNP) and correlating allelic differences with hematologic response (HR) or molecular response (MR) in PEG-IFN-treated patients did not reveal any significant genome-wide associations. However, in a hypothesis-driven approach investigating the role of the IFNL4 gene locus variants, the authors demonstrated a significant genomic correlation between non-functional IFNL4 variants and improved MR (not HR).
The IFNL4 gene is a polymorphic pseudogene, which translates into the functional IFNL4 protein only in some humans. The gene is polymorphic in humans, and the TT allele for the variants rs368234815 and rs8099917 produces a frameshift in the coding region leading to a non-coding mRNA. Similarly, for the rs12979860 variant, a CC allele leads to lack of IFNL4 expression. In contrast, the rs117648444 variant can come with a G allele leading to the expression of an impaired IFNL4-S70 protein, while the non-G allele produces the fully functional IFNL4-P70 protein. Interestingly, non-coding IFNL4 SNPs (rs12979860, rs8099917) have previously shown to be associated with response to PEG-IFN and viral clearance during hepatitis C virus infection.
In accordance with results for hepatitis C virus treatment, the investigated PV population showed a significant genotypic association of the non-coding alleles of rs368234815 (OR, 6.10; 95% CI, 1.49–36.64; p = 0.00065), rs8099917 (OR, 4.60; 95% CI, 1.39–16.69; p = 0.0071), and rs12979860 (OR, 6.10; 95% CI, 1.49–36.64; p = 0.0065) for MR at 36 months follow-up.
Based on that finding, the authors investigated diplotypes of these variants in patients, which comprises three functional classes: no IFNL4, nonfunctional IFNL4-S70, and active IFNL4-P70. As was expected, MR (but not HR) was strongly associated with the absence of IFNL4 (89.3%) versus a completely functional IFNL4-P70 (43.3%) protein. Interestingly, the impaired IFNL4-S70 induced similar responses to no IFNL4 (Table 1).
Table 1. Influence of IFNL4 diplotypes on the molecular response in PEG-IFN treatment of PV1
CI, confidence interval; IFNL4, interferon lambda 4; n, number of patients; NR, non-responders; N (no IFNL4); OR, odds ratio; P, IFNL4-P70; R, responders; S, IFNL4-S70. |
|||||||
Variant/ |
Diploid |
n |
NR, n |
R, n |
R, % |
OR, 95% CI |
P value |
---|---|---|---|---|---|---|---|
Contribution of IFNL4-S70 and no-IFNL4 compared with IFNL4-P70 alone |
|||||||
IFNL4-P70 alone |
P/N and P/P |
26 |
15 |
11 |
42.3 |
Reference |
|
IFNL4-S70 and S70/P70 |
N/S and P/S |
15 |
3 |
12 |
80.0 |
5.23, 1.06–35.87 |
0.0254 |
no IFNL4 |
N/N |
28 |
3 |
25 |
89.3 |
10.80, 2.39–69.97 |
0.000391 |
Contribution of IFNL4-S70 compared with no-IFNL4 |
|||||||
no IFNL4 |
N/N |
28 |
3 |
25 |
89.3 |
Reference |
|
IFNL4-S70 and S70/P70 |
N/S and P/S |
15 |
3 |
12 |
80.0 |
0.49, 0.06–4.20 |
0.6474 |
These results were confirmed in 27 patients treated in the PEGINVERA trial, where a consistent trend for a better MR after PEG-IFN treatment was observed in patients lacking functional IFNL4 at 24 months follow-up (p = 0.068).
In patients with PV treated with PEG-IFN, lack of functional IFNL4 expression status confers a significantly better MR indicating deeper responses which the potential for cure. In contrast, no differences were observed for HR. These data may have implications for optimizing patient management during PEG-IFN treatment, warranting further confirmation in bigger patient cohorts.
References
Please indicate your level of agreement with the following statements:
The content was clear and easy to understand
The content addressed the learning objectives
The content was relevant to my practice
I will change my clinical practice as a result of this content