Polymorphisms in key bone modulator cytokines genes influence bisphosphonates therapy in postmenopausal women

PFN1 Gene Polymorphisms and the Bone Mineral Density Response to Alendronate Therapy in Postmenopausal Chinese Women with Low Bone Mass

Purpose

Alendronate is a widely used anti-osteoporotic drug. PFN1 gene is a newly identified early-onset Paget’s disease pathogenic gene. The purpose of this study is to study whether the genetic variations in this gene affect the clinical efficacy of alendronate in postmenopausal Chinese women with low bone mass.

Patients and Methods

Seven single nucleotide polymorphisms in PFN1 gene were genotyped. A total of 500 postmenopausal women with osteoporosis or osteopenia were included. All participants were treated with weekly alendronate 70 mg for 12 months. A total of 466 subjects completed the follow-up. Bone mineral density (BMD) of lumbar spine, femoral neck and total hip were measured at baseline and after treatment.

Results

After 12 months of treatment, the BMD of lumbar spine, femoral neck and total hip all increased significantly (all P < 0.001), with an average increase of 4.72 ± 5.31%, 2.08 ± 4.45%, and 2.42 ± 3.46%, respectively. At baseline, there were no significant differences in BMD at lumbar spine, femoral neck and total hip between different genotype groups (P > 0.05). We failed to identify any significant association between the genotypes or haplotypes of PFN1 and the BMD response to alendronate therapy.

Conclusion

Genetic polymorphisms of PFN1 may not be a major contributor to the therapeutic response to alendronate treatment in Chinese women with low bone mass.

Bone metabolism genes variation and response to bisphosphonate treatment in women with postmenopausal osteoporosis

Introduction

Long-term treatment is used in patients with osteoporosis, and bisphosphonates (BPs) are the most commonly prescribed medications. However, in some patients this therapy is not effective, cause different side effects and complications. Unfortunately, at least one year is needed to identify and confirm an ineffectiveness of BPs therapy on bone mineral density (BMD). Among other factors, a response to BPs therapy may also be explained by genetic factors. The aim of this study was to analyze the influence of SOST, PTH, FGF2, FDPS, GGPS1, and LRP5 gene variants on the response to treatment with aminobisphosphonates.

Materials and methods

Women with postmenopausal osteoporosis were included to this study if they used aminobisphosphonates for at least 12 months. Exclusion criteria were: persistence on BPs therapy less than 80%, bone metabolic diseases, diseases deemed to affect bone metabolism, malignant tumours, using of any medications influencing BMD. The study protocol was approved by the local ethics committee. The BMD at the lumbar spine and femoral neck were measured using dual x-ray absorptiometry (GE Lunar) before and at least 12 months after treatment with BPs. According to BMD change, patients were divided in two groups–responders and non-responders to BPs terapy. Polymorphic variants in SOST, PTH, FGF2, FDPS, GGPS1, and LRP5 genes were determined using PCR analysis with TaqMan probes (Thermo Scientific).

Results

In total, 201 women with BPs therapy were included in the study. No statistically significant differences were observed in age, age at menopause, weight, height, BMI and baseline BMD levels between responders (122 subjects) and non-responders (79 subjects).

As single markers, the SOST rs1234612 T/T (OR = 2.3; P = 0.02), PTH rs7125774 T/T (OR = 2.8, P = 0.0009), FDPS rs2297480 G/G (OR = 29.3, P = 2.2×10⁻⁷), and GGPS1 rs10925503 C/C+C/T (OR = 2.9; P = 0.003) gene variants were over-represented in non-responders group. No significant association between FGF2 rs6854081 and LRP5 rs3736228 gene variants and response to BPs treatment was observed. The carriers of T-T-G-C allelic combination (constructed from rs1234612, rs7125774, rs2297480, and rs10925503) were predisposed to negative response to BPs treatment (OR = 4.9, 95% CI 1.7–14.6, P = 0.005). The C-C-T-C combination was significantly over-represented in responders (OR = 0.1, 95% CI 0.1–0.5, P = 0.006).

Conclusions

Our findings highlight the importance of identified single gene variants and their allelic combinations for pharmacogenetics of BPs therapy of osteoporosis. Complex screening of these genetic markers could be used as a new strategy for personalized antiresorptive therapy.