Association of higher plasma vitamin D binding protein and lower free calcitriol levels with tenofovir disoproxil fumarate use and plasma and intracellular tenofovir pharmacokinetics: cause of a functional vitamin D deficiency?

Tenofovir induced Fanconi syndrome in a middle age African female from Kenya, East Africa: Case report and brief literature review

This case presentation highlights the need to routinely monitor renal function in patients on Tenofovir Disoproxil Fumarate (TDF) due to its side effect of proximal tubule dysfunction.

Abstract

This is a case presentation of a 50-year-old African female who had been on a Tenofovir based regimen for 12 years and developed Fanconi syndrome. She recovered after discontinuation of the Tenofovir Disoproxil Fumarate (TDF).

The effect of daily oral PrEP use during pregnancy on bone mineral density among adolescent girls and young women in Uganda

Introduction

Oral pre-exposure prophylaxis (PrEP) is recommended during pregnancy for at-risk cisgender women. Pregnancy is known to impede bone growth and tenofovir-based PrEP may also yield detrimental changes to bone health. Thus, we evaluated the effect of PrEP use during pregnancy on bone mineral density (BMD).

Methods

We used data from a cohort of women who were sexually active, HIV-negative, ages 16-25 years, initiating DMPA or choosing condoms for contraception and enrolled in the Kampala Women's Bone Study. Women were followed quarterly with rapid testing for HIV and pregnancy, PrEP dispensation, and adherence counseling. Those who became pregnant were counseled on PrEP use during pregnancy per national guidelines. BMD of the neck of the hip, total hip, and lumbar spine was measured using dual-energy x-ray absorptiometry at baseline and annually. We compared the mean percent change in BMD from baseline to month 24.

Results

Among 499 women enrolled in the study, 105 pregnancies occurred in 90 women. At enrollment, the median age was 20 years (IQR: 19-21) and 89% initiated PrEP. During pregnancy, 67% of women continued using PrEP and PrEP was dispensed in 64% of visits. BMD declined significantly in women using PrEP during pregnancy compared to women who were not pregnant nor used PrEP: relative BMD change was -2.26% (95% CI: -4.63 to 0.11, p = 0.06) in the femoral neck, -2.57% (95% CI: -4.48 to -0.66, p = 0.01) in total hip, -3.06% (95% CI: -5.49 to -0.63, p = 0.001) lumbar spine. There was no significant difference in BMD loss when comparing PrEP-exposed pregnant women to pregnant women who never used PrEP. Women who became pregnant were less likely to continue PrEP at subsequent study visits than women who did not become pregnant (adjOR: 0.25, 95% CI: 0.16-0.37, p < 0.001). Based on pill counts, there was a 62% reduction in the odds of high PrEP adherence during pregnancy (adjOR = 0.38, 95% CI: 0.27-0.58, p < 0.001).

Conclusion

Women who used PrEP during pregnancy experienced a similar reduction in BMD as pregnant women with no PrEP exposure, indicating that BMD loss in PrEP-using pregnant women is largely driven by pregnancy and not PrEP.

Changes in bone quality after switching from a TDF to a TAF based ART: A pilot randomized study

BACKGROUND

The impact of tenofovir disoproxil fumarate (TDF) antiretroviral (ART) regimens on bone health has been characterized mostly by bone mineral density (BMD), but recently also by bone quality (BQ). The aim of this pilot study is to assess the changes in BMD and BQ after switch from TDF to tenofovir alafenamide (TAF) ART.

METHODS

HIV individuals receiving TDF-based ART were randomized to switch to Bictegravir-TAF-Emtricitabine or to remain in the same regimen. At baseline and 24-weeks after randomization, participants underwent bone mineral density (BMD) by DXA and BQ assessment using bone microindentation, a validated technique that measures bone tissue quality expressed as bone material strength index (BMSi). A panel of plasma bone turnover biomarkers were measured by ELISA at the same time-points. Values are expressed as median [interquartile range] and non-parametric tests were used where appropriate.

RESULTS

A total of 24 HIV individuals were included in the study, 19 of which were men (80%). Median age at baseline was 43 years (IQR 38-54). Half of individuals were allocated in the TDF group while the other half changed to TAF treatment. No differences at baseline between both groups were detected in any parameter. Non-significant changes nor in lumbar or femoral BMD at week 24 was found in any regimen. In contrast, there was an increase in BMSi in the TAF arm at 24 weeks, and thus an improvement in BQ[81.6 (79-83) to 86 (80-88) (+5.1%);p=0.041], whereas the TDF arm remained stable from 82 (76-85) at baseline to 82 (73-83);p=0.812. Hence, at week 24 there were significant differences in BQ between arms (p=0.049). A reduction in bone formation markers was found at week 24 in both regimens: N-terminal propeptide of type-1 collagen decreased a 20% (-35 - -0.6); p=0.031 with TAF and -16% (-25 - -5); p=0.032 with TDF. Also a decrease in bone resorption marker C-telopeptide with TAF was detected [-10% (-19 - -5);p=0.028] but not with TDF (p=0.232), suggesting a less metabolically active bone after switching to TAF.

CONCLUSION

A bone quality improvement was found after switching from a TDF to a TAF based ART independently of BMD, suggesting that the bone health benefits of TAF may extend beyond BMD. Future research should be directed to confirm these findings and to identify the underlying mechanisms of ART related bone toxicity.

A Systematic Review and Meta-Analysis of Randomized Controlled Trials of the Effects of Vitamin D Supplementation on Children and Young Adults with HIV Infection

BACKGROUND

Children and young adults with HIV infection may exhibit vitamin D deficiency, which is harmful to bone health as well as the endocrine and immune systems.

OBJECTIVES

This study sought to investigate the effect of vitamin D supplementation on children and young adults with HIV infection.

METHODS

The PubMed, Embase, and Cochrane databases were searched. Randomized controlled trials that have evaluated the effects of vitamin D supplementation (ergocalciferol or cholecalciferol) at any dose or for any duration in children and young adults with HIV infection, aged 0-25 y, were included. A random-effects model was used, and the standardized mean difference (SMD) and 95% CI were calculated.

RESULTS

Ten trials, with 21 publications and 966 participants (mean age: 17.9 y), were included in the meta-analysis. The supplementation dose and the duration of the studies included ranged from 400 to 7000 IU/d and from 6 to 24 mo, respectively. Vitamin D supplementation was associated with a significantly higher serum 25(OH)D concentration at 12 mo (SMD: 1.14; 95% CI: 0.64, 1.65; P < 0.00001) compared with a placebo. No significant difference was observed in spine BMD (SMD: -0.09; 95% CI: -0.47, 0.3; P = 0.65) at 12 mo between these 2 groups. However, participants who received higher doses (1600-4000 IU/d) had significantly higher total BMD (SMD: 0.23; 95% CI: 0.02, 0.44; P = 0.03) and nonsignificantly higher spine BMD (SMD: 0.3; 95% CI: -0.02, 0.61; P = 0.07) at 12 mo compared with those who received standard doses (400-800 IU/d).

CONCLUSIONS

Vitamin D supplementation in children and young adults with HIV infection increases the serum 25(OH)D concentration. A relatively high daily dose of vitamin D (1600-4000 IU) improves total BMD at 12 mo and results in sufficient 25(OH)D concentrations.

Tenofovir-induced osteopenia and hyperparathyroidism: A case report and literature review

Tenofovir disoproxil fumarate is the first-line antiviral therapy for chronic viral hepatitis B, but long-term use is associated with renal failure and hypophosphatemic osteomalacia. Tenofovir disoproxil fumarate-induced osteoporosis and secondary hyperparathyroidism are less commonly reported. Herein, we describe the case of a patient with bone and multijoint pain who was initially misdiagnosed as having normocalcemic primary hyperparathyroidism associated with prolonged exposure to tenofovir disoproxil fumarate. The patient's 24-h urinary calcium and phosphorus excretion levels and serum calcium levels were at the lower end of the normal range. After reviewing these findings, the diagnosis was amended to osteoporosis and secondary hyperparathyroidism caused by tenofovir disoproxil fumarate. In this report, we describe the differences in clinical and laboratory manifestations of hyperparathyroidism induced by tenofovir disoproxil fumarate and normocalcemic primary hyperparathyroidism. We also discuss relevant pathophysiological mechanisms and propose a feasible treatment strategy.

Tenofovir-induced renal and bone toxicity: report of two cases and literature review

Tenofovir Disoproxil Fumarate (TDF) is one of the drugs in the initial first-line antiretroviral regimen for the treatment of hepatitis B and HIV infections. Despite its effectiveness and few adverse effects, it is related to renal and bone toxicity. We described two cases of HIV-positive middle-aged women who had been using TDF for two and four years (cases 1 and 2, respectively) and were admitted to the emergency room. Case 1 presented with metabolic ileum and diffuse bone pain while case 2 presented with bilateral coxo-femoral pain after a fall from standing height. Both cases had similar laboratory tests: hyperchloremic metabolic acidosis, hypophosphatemia, hypokalemia, hypouricemia and elevated plasma creatinine. In urinary exams, there was evidence of renal loss of electrolytes, justifying the serum alterations, in addition to glucosuria and proteinuria. The bone pain investigation identified bone fractures and reduced bone mineral density, together with increased levels of parathyroid hormone, alkaline phosphatase and vitamin D deficiency. These two cases illustrate the spectrum of adverse renal and bone effects associated with TDF use. TDF was discontinued and treatment was focused on correcting the electrolyte disturbances and acidosis, in addition to controlling the bone disease through vitamin D and calcium supplementation. The renal changes found in both cases characterized the Fanconi’s syndrome, and occurred due to TDF toxicity to proximal tubule cells mitochondria. Bone toxicity occurred due to direct interference of TDF in bone homeostasis, in addition to vitamin D deficiency and phosphaturia resulting from tubulopathy. During the follow-up, both cases evolved with chronic kidney disease and in one of them, the Fanconi’s syndrome did not revert. We emphasize the need to monitor markers of bone metabolism and glomerular and tubular functions in patients using TDF.

Tenofovir-diphosphate in peripheral blood mononuclear cells during low, medium and high adherence to emtricitabine/ tenofovir alafenamide vs. emtricitabine/ tenofovir disoproxil fumarate

OBJECTIVE

Tenofovir alafenamide (TAF) preferentially loads peripheral blood mononuclear cells (PBMCs), resulting in higher PBMC tenofovir-diphosphate (TFV-DP) vs. tenofovir disoproxil fumarate (TDF). No studies have yet compared TFV-DP in PBMC from lower than daily dosing between prodrugs, which has potential implications for event-driven preexposure prophylaxis and pharmacologic forgiveness.

DESIGN

Two separate randomized, directly observed therapy (DOT) crossover studies (DOT-DBS and TAF-DBS) were conducted to mimic low, medium and high adherence.

METHODS

HIV-negative adults were randomized to two 12-week DOT regimens of 33, 67 or 100% of daily dosing with emtricitabine (F)/TAF 200 mg/25 mg (TAF-DBS) or F/TDF 200 mg/300 mg (DOT-DBS), separated by a 12-week washout. PBMC steady-state concentrations (Css) of TFV-DP and FTC-TP were estimated using nonlinear mixed models and compared between F/TAF and F/TDF.

RESULTS

Thirty-five participants contributed to 33% (n = 23), 67% (n = 23) and 100% (n = 23) of daily F/TAF regimens. Forty-four contributed to 33% (n = 15), 67% (n = 16) and 100% (n = 32) of daily F/TDF regimens. PBMC TFV-DP Css were 7.3 [95% confidence interval (95% CI): 6.4-8.2], 7.1 (5.9-8.2) and 6.7- (4.4-8.9) fold higher (P < 0.0001) following F/TAF vs. F/TDF; 593 vs. 81.7, 407 vs. 57.4, and 215 vs. 32.3 fmol/106 cells, respectively. TFV-DP was 2.6 (2.1-3.1) fold higher with 33% F/TAF vs. 100% F/TDF. Estimated half-lives (95% CI) of TFV-DP in PBMC were 2.9 (1.5-5.5) days for F/TAF and 2.1 (1.5-2.9) days for F/TDF. FTC-TP was similar in both studies (P = 0.119).

CONCLUSION

F/TAF produced 6.7 to 7.3-fold higher TFV-DP in PBMC vs. F/TDF across adherence levels, supporting increased potency and pharmacologic forgiveness with F/TAF in the PBMC compartment.

Vitamin D as Modulator of Drug Concentrations: A Study on Two Italian Cohorts of People Living with HIV Administered with Efavirenz

To date, vitamin D seems to have a significant role in affecting the prevention and immunomodulation in COVID-19 disease. Nevertheless, it is important to highlight that this pro-hormone has other several activities, such as affecting drug concentrations, since it regulates the expression of cytochrome P450 (CYP) genes. Efavirenz (EFV) pharmacokinetics is influenced by CYPs, but no data are available in the literature concerning the association among vitamin D levels, seasonality (which affects vitamin D concentrations) and EFV plasma levels. For this reason, the aim of this study was to evaluate the effect of 25-hydroxy vitamin D (25(OH)D3) levels on EFV plasma concentrations in different seasons. We quantified 25(OH)D3 by using chemiluminescence immunoassay, whereas EFV plasma concentrations were quantified with the HPLC–PDA method. A total of 316 patients were enrolled in Turin and Rome. Overall, 25(OH)D3levels resulted in being inversely correlated with EFV concentrations. Some patients with EFV levels higher than 4000 ng/mL showed a deficient 25(OH)D3 concentration in Turin and Rome cohorts and together. EFV concentrations were different in patients without vitamin D supplementation, whereas, for vitamin D-administered individuals, no difference in EFV exposure was present. Concerning seasonality, EFV concentrations were associated with 25(OH)D3 deficiency only in winter and in spring, whereas a significant influence was highlighted for 25(OH)D3 stratification for deficient, insufficient and sufficient values in winter, spring and summer. A strong and inverse association between 25(OH)D3and EFV plasma concentrations was suggested. These data suggest that vitamin D is able to affect drug exposure in different seasons; thus, the achievement of the clinical outcome could be improved by also considering this pro-hormone.

Vitamin D and Calcium Supplement Attenuate Bone Loss among HIVInfected Patients Receiving Tenofovir Disoproxil Fumarate/Emtricitabine/ Efavirenz: An Open-Label, Randomized Controlled Trial

BACKGROUND

Antiretroviral therapy (ART), especially with tenofovir disoproxil fumarate (TDF), has been associated with accelerated bone turnover and leads to significant bone loss.

OBJECTIVE

We aimed to determine the effect of vitamin D2 and calcium on bone mineral density (BMD) in HIV-infected patients receiving TDF/emtricitabine (FTC)/efavirenz (EFV).

METHODS

A prospective, open-label, randomized controlled study was conducted. Eligible patients were ART naïve HIV individuals who initiated TDF/FTC/EFV. The study group received supplementation with vitamin D2 and calcium carbonate, whereas the control group was administered only ART. The primary outcome was the percentage change in total hip BMD at week 24 compared with baseline.

RESULTS

A total of 18 patients were randomized (9 in each group). The mean (standard deviation; SD) total hip BMD significantly decreased from baseline in both groups, from 0.96 (0.14) g/cm2 to 0.93 (0.13) g/cm2 in the study group (p = 0.006) and from 0.87 (0.11) g/cm2 to 0.84 (0.11) g/cm2 in the control group (p = 0.004). The mean (SD) lumbar spine BMD significantly decreased from baseline in both groups, from 1.00 (0.13) g/cm2 to 0.97 (0.13) g/cm2 (p = 0.004) in the study group and from 0.90 (0.09) g/cm3 to 0.86 (0.08) g/cm2 in the control group (p = 0.006). At week 24, the mean (SD) lumbar spine BMD was significantly greater in the study group than in the control group (p = 0.042). However, there were no significant differences in the percentage change of total hip, lumbar spine, and femoral neck BMD between both groups. No adverse events were reported. In conclusion, as early as 24 weeks after TDF initiation, a significant decline in BMD was detected.

CONCLUSION

Vitamin D2 and calcium supplements should be considered for HIV-infected patients receiving TDF/FTC/EFV in a resource-limited setting where there are limited ART options (Clinicaltrials. gov NCT0287643).

Risk Factors of Hypovitaminosis D in HIV-Infected Patients on Suppressive Antiretroviral Therapy

Low serum vitamin D levels are very common in human immunodeficiency virus (HIV)-infected patients. In our cross-sectional study, we investigated the association between 25-hydroxyvitamin D (25(OH)D) levels and serum inflammation markers [C-reactive protein (CRP), white blood cells (WBC), D-dimers, platelet count (PLT)] in 148 HIV-infected patients on combined antiretroviral therapy [28 on tenofovir alafenamide (TAF)] and 40 healthy controls. The controls were significantly older (56.6 ± 19.1 years for HIV(-) vs. 45.1 ± 11.8 years for HIV(+); p = .001) and more females were observed in this group (65% for HIV(-) vs. 16.7% for HIV(+); p = .001). The vitamin D serum level was comparable in the two studied groups (74.2 ± 35.9 nmol/L for HIV(+) vs. 78.0 ± 27.6 nnmol/L for HIV(-), p = .545). In HIV-infected group, a significant positive correlation between CD4+ cell percentage and vitamin D level was observed (r = 0.17; p = .036). Furthermore, the significant negative correlation between vitamin D level and CD8+ cell percentage, PLT, CRP, and D-dimers was seen. In univariate analysis, only TAF use and AIDS status was associated with vitamin D level deficiency. No other antiretroviral (ARV) drug nor gender or smoking had influence on vitamin D serum level. In multivariate analysis, only AIDS status and CRP level were correlated with vitamin D level (slope estimate = 11.6 and p = .032 and slope estimate = -0.83 and p = .002; respectively). In summary, we report that low vitamin D level may be associated with high CRP level in HIV-infected patients on suppressive antiretroviral therapy, especially in AIDS phase. More larger studies are required to assess our observation concerning TAF use and vitamin D level in HIV-positive patients.

Hypophosphataemia after ferric carboxymaltose is unrelated to symptoms, intestinal inflammation or vitamin D status

Background

Intravenous iron replacement is recommended for iron-deficient patients with inflammatory bowel disease (IBD), but may be associated with hypophosphataemia, predisposing to osteomalacia and fractures. This study aimed to evaluate the incidence and risk factors for hypophosphataemia following intravenous ferric carboxymaltose (FCM) in patients with IBD.

Methods

This prospective observational study of patients with and without IBD evaluated serum phosphate for 28 days following intravenous FCM, and assessed associations with symptoms, markers of inflammation and vitamin D status.

Results

Twenty-four patients with IBD (11 with Crohn’s disease [CD], 13 with ulcerative colitis [UC], mean age 45 years [range 19–90], 7 female), and 20 patients without IBD (mean age 56 [22–88] y, 11 female), were included. Overall, serum phosphate declined by a mean of 36% at Day 7, with a mean fall of 42% (SD 19%) at some time point over 28 days (p <  0.001). Twenty-four of 44 (55%) patients developed moderate to severe hypophosphataemia (serum phosphate < 0.6 mmol/L). No differences between patients with and without IBD were seen, but patients with CD had greater decline in phosphate than those with UC. There was no association between hypophosphataemia and symptomatic adverse events, faecal calprotectin, C-reactive protein, albumin, platelet count, 25(OH) vitamin D, or 1,25(di-OH) vitamin D. Serum phosphate < 1.05 mmol/L on Day 2 predicted susceptibility to moderate-severe hypophosphataemia (OR 7.0).

Conclusions

Hypophosphataemia following FCM is common, unrelated to symptomatic adverse events, baseline intestinal or systemic inflammation, or vitamin D status.

Fractures Related to Tenofovir: A Case/Noncase Study in the European Pharmacovigilance Database

BACKGROUND

There is no clear consensus on the relationship between tenofovir (TDF) and fracture risk because the studies published so far present contradictory findings.

STUDY QUESTION

Our objective was to detect, from the European pharmacovigilance database (EudraVigilance), a signal of fracture risk during TDF exposure in patients infected with HIV.

METHODS

Herein, we analyze all the cases of fractures suspected to be related to TDF recorded in EudraVigilance between 2001 and November 10, 2016. A case/noncase method was used to assess the association between fractures and TDF, calculating proportional reporting ratios (PRRs) and their 95% confidence intervals (CIs) as a measure of disproportionality. According to the Medical Dictionary for Regulatory Activities (MedDRA) terminology, osteoporotic fractures are included in High Level Group Term (HLGT) "Fractures" and traumatic fractures in HLGT "Bone and joint injuries," so, we selected cases included in both HLGTs. The noncases used as controls were all the remaining adverse drug reaction reports recorded in EudraVigilance during the same period.

RESULTS

There were 68,113 cases of fractures in the 4,776,472 reports recorded in EudraVigilance during the study period. TDF was involved in 181 cases. The median latency period until the appearance of fracture was 995 days. TDF was present as the only suspect drug in 140 cases. The PRR of TDF and fractures was 1.11 (95% CI, 0.96-1.28). Nevertheless, disproportionality was observed for some types of fractures: osteoporotic fractures (PRR 17.24; 95% CI, 9.90-30.01), bone fissure (PRR 16.60; 95% CI, 6.11-45.10), and pathological fracture (PRR 4.40; 95% CI, 2.77-7.00).

CONCLUSIONS

Our findings do not show a disproportionality for fractures in patients treated with TDF, although disproportionality was found for some types of fractures, mainly osteoporotic fractures.

The effect of tenofovir disoproxil fumarate on bone mineral density: a systematic review and meta-analysis

BACKGROUND

We conducted a systematic review and meta-analysis (CRD#42017070552) to quantify the impact of oral tenofovir disoproxil fumarate/emtricitabine (TDF/FTC) on bone mineral density (BMD) and the risk of osteoporosis, low bone mass and fractures, among people taking it as pre-exposure prophylaxis (PrEP), HIV treatment and HBV treatment.

METHODS

We searched MEDLINE and EMBASE for randomized controlled trials published from 1997-2018 reporting BMD, osteoporosis, low bone mass and/or fractures in treatment-naive patients taking compared with not taking TDF for 48 ±4 weeks. We pooled outcomes using DerSimonian random-effects models.

RESULTS

Our search yielded 5,178 abstracts, representing 3,865 articles, with 25 meeting the inclusion criteria. TDF was associated with greater BMD decline when taken as PrEP (lumbar spine: mean difference [MD]=-0.82%, 95% CI=-1.28, -0.37%, I²=38%; total hip: MD=-0.81%, 95% CI=-1.22, -0.40%, I²=48%) and HIV treatment (lumbar spine: MD=-1.62%, 95% CI=-2.30, -0.95%, I²=93%; total hip: MD=-1.75%, 95% CI=-2.08, -1.42%, I²=83%; femoral neck: MD=-1.26%, 95% CI=-2.15, -0.38%, I²=43%) in comparison to those not taking TDF. Eight studies reported on incident osteoporosis or low bone mass, with variable results. Pooled results from five PrEP studies showed that TDF was not associated with increased fractures compared with no PrEP (RR=1.12, 95% CI=0.752, 1.74, I²=26%).

CONCLUSIONS

TDF caused greater decreases in BMD than did comparators when used for all three indications and the magnitude of this decrease was larger for HIV treatment compared with PrEP. Fractures were not increased among PrEP patients. The clinically significant BMD decline caused by TDF and current expansion of PrEP use suggest attention to the adverse bone effects of TDF will increase in importance.

Pharmacogenetic determinants of kidney-associated urinary and serum abnormalities in antiretroviral-treated HIV-positive patients

Tenofovir disoproxyl fumarate (TDF) has been associated with renal tubular abnormalities, phosphaturia and proteinuria (retinol binding protein, RBP, loss): vitamin D (VD) and PTH affect these markers. Aim was to understand if some single nucleotide polymorphisms (SNPs) were predictors of renal abnormalities in an Italian cohort of HIV-affected patients. DNA was analyzed through real-time PCR, urinary RBP corrected by creatinine (uRBP/Cr). The majority of patients received TDF. Abnormal uRBP/Cr was more frequent in TDF recipients: eGFR <90 mL/min and TDF were predictors in the whole cohort, whereas eGFR <90 mL/min, TDF concentrations and CYP24A1-3999TT in TDF-treated patients. Phosphate levels were higher low VD level patients: age <50 years, CYP27B1 + 2838CC genotype and non-European ancestry were predictors. PTH levels were border-line higher in TDF patients: non-European ancestry, females, TDF, VD levels < 30 ng/mL and SLC28A2-124CT/TT and ABCC2-24CC were predictors. For the first time, SNPs were associated with PTH, phosphate, calcium and tubular dysfunction in HIV-infected patients.

Vitamin D3 Supplementation Increases Spine Bone Mineral Density in Adolescents and Young Adults With Human Immunodeficiency Virus Infection Being Treated With Tenofovir Disoproxil Fumarate: A Randomized, Placebo-Controlled Trial

Background

Tenofovir disoproxil fumarate (TDF) decreases bone mineral density (BMD). We hypothesized that vitamin D3 (VITD3) would increase BMD in youth receiving TDF.

Methods

This was a randomized, double-blind, placebo-controlled trial of directly observed VITD3 vs placebo every 4 weeks for 48 weeks in youth aged 16-24 years with HIV, RNA load <200 copies/mL, taking TDF-containing combination antiretroviral therapy (TDF-cART) for ≥180 days. Participants (N = 214) received a daily multivitamin containing VITD3 400 IU and calcium 162 mg, plus monthly randomized VITD3 50000 IU (n = 109) or placebo (n = 105). Outcome was change from baseline to week 48 in lumbar spine BMD (LSBMD). Data presented are median (Q1, Q3).

Results

Participants were aged 22.0 (21.0, 23.0) years, 84% were male, and 74% were black/African American. At baseline, 62% had 25-hydroxy vitamin D (25-OHD) <20 ng/mL. Multivitamin adherence was 49% (29%, 69%), and VITD3/placebo adherence 100% (100%, 100%). Vitamin D intake was 2020 (1914, 2168) and 284 (179, 394) IU/day, and serum 25-OHD concentration was 36.9 (30.5, 42.4) and 20.6 (14.4, 25.8) ng/mL at 48 weeks in VITD3 and placebo groups, respectively (P < .001). From baseline to week 48, LSBMD increased by 1.15% (-0.75% to 2.74%) in the VITD3 group (n = 99; P < .001) and 0.09% (-1.49% to 2.61%) in the placebo group (n = 89; P = .25), without between-group difference (P = .12). VITD3 group changes occurred with baseline 25-OHD <20 ng/mL (1.17% [-.82% to 2.90%]; P = .004) and ≥20 ng/mL (0.93% [-.26% to 2.15%]; P = .033).

Conclusions

For youth taking TDF-cART, LSBMD increased through 48 weeks with VITD3 plus multivitamin, but not with placebo plus multivitamin, independent of baseline vitamin D status.

Clinical Trials Registration

NCT01751646.

Treatment of Human Immunodeficiency Virus Infection With Tenofovir Disoproxil Fumarate-Containing Antiretrovirals Maintains Low Bone Formation Rate, But Increases Osteoid Volume on Bone Histomorphometry

Bone mineral density (BMD) loss is a known complication of human immunodeficiency virus (HIV) infection and its treatment, particularly with tenofovir disoproxil fumarate (TDF)-containing antiretroviral regimens. Although renal proximal tubular dysfunction and phosphaturia is common with TDF, it is unknown whether BMD loss results from inadequate mineralization. We evaluated change in BMD by dual-energy X-ray absorptiometry (DXA) and bone histomorphometry by tetracycline double-labeled transiliac crest biopsies in young men living with HIV before (n = 20) and 12 months after (n = 16) initiating TDF/lamivudine/efavirenz. We examined relationships between calciotropic hormones, urinary phosphate excretion, pro-inflammatory and pro-resorptive cytokines, and bone remodeling-related proteins with changes in BMD and histomorphometry. Mean age was 29.6 ± 5.5 years, with mean CD4 + T cell count of 473 ± 196 cells/mm³ . At baseline, decreased bone formation rate and increased mineralization lag time were identified in 16 (80%) and 12 (60%) patients, respectively. After 12 months, we detected a 2% to 3% decrease in lumbar spine and hip BMD by DXA. By histomorphometry, we observed no change in bone volume/total volume (BV/TV) and trabecular parameters, but rather, increases in cortical thickness, osteoid volume, and osteoblast and osteoclast surfaces. We did not observe significant worsening of renal phosphate excretion or mineralization parameters. Increases in PTH correlated with decreased BMD but not histomorphometric parameters. Overall, these data suggest abnormalities in bone formation and mineralization occur with HIV infection and are evident at early stages. With TDF-containing antiretroviral therapy (ART), there is an increase in bone remodeling, reflected by increased osteoblast and osteoclast surfaces, but a persistence in mineralization defect, resulting in increased osteoid volume. © 2019 American Society for Bone and Mineral Research.

Effect of Vitamin D Supplementation on Bone Turnover Markers During HIV Pre-Exposure Prophylaxis Using Tenofovir Disoproxil Fumarate-Emtricitabine in Men Who Have Sex with Men

Pre-exposure prophylaxis (PrEP) with tenofovir disoproxil fumarate-emtricitabine (TDF-FTC) reduces bone mineral density in HIV-uninfected men who have sex with men (MSM). We hypothesized that PrEP with TDF-FTC would increase bone turnover markers (BTMs) at week 24 and that vitamin D supplementation from weeks 24 to 48 would blunt this increase. Participants were from a cohort of 398 MSM and transgender women who received daily TDF-FTC for PrEP. At week 24, a prospective intervention group initiated vitamin D3 4,000 IU daily. Concurrent controls were selected from the cohort who took ≤400 IU/day of vitamin D3 matched by age, race, and body mass index. The primary endpoint was the change in procollagen-I N-terminal propeptide (P1NP) from weeks 24 to 48. Paired t-tests were used to compare changes in BTMs between intervention and controls. Among 48 intervention-control pairs, median age was 33 years. At baseline, 68.9% of the intervention group and 77.3% of controls were vitamin D sufficient (≥20 ng/mL, p = .94). P1NP, C-telopeptide, parathyroid hormone (PTH), and 25-OH vitamin D3 did not increase significantly at week 24. P1NP fell by a mean ± SD of -27.6 ± 49.9 pg/mL from weeks 24 to 48 with vitamin D and -2.5 ± 40.2 pg/mL in controls (p = .01). There were no significant between-group differences in the weeks 24-48 change in C-telopeptide, PTH, or 25-OH vitamin D3. Vitamin D3 supplementation with 4,000 IU/day resulted in a significant reduction in the BTM P1NP compared with controls, suggesting that this intervention has potential to improve bone health during PrEP.

Continued Interest and Controversy: Vitamin D in HIV

PURPOSE OF REVIEW

Vitamin D (VitD) deficiency is highly prevalent among HIV-infected individuals. Given the overlapping risk for several chronic disease and immunomodulatory outcomes from both long-standing HIV and VitD deficiency, there is great interest in clarifying the clinical role of VitD for this population.

RECENT FINDINGS

Recent studies have expanded our knowledge regarding the epidemiology and mechanisms of VitD deficiency-associated outcomes in the setting of HIV. Clinical trials focusing on VitD supplementation have demonstrated a positive impact on bone mineral density in subgroups of HIV-infected individuals initiating ART or on suppressive ART regimens; however, significant heterogeneity exists between studies and data are less consistent with other clinical outcomes. Further research is needed to clarify uncertainly in several domains, including identifying patients at greatest risk for poor outcomes from VitD deficiency, standardizing definitions and measurement techniques, and better quantifying the benefits and risks of VitD supplementation across different demographic strata for skeletal and extra-skeletal outcomes.

A Randomized Placebo-Controlled Trial of Low- Versus Moderate-Dose Vitamin D3 Supplementation on Bone Mineral Density in Postmenopausal Women With HIV

BACKGROUND

Prevalence of osteoporosis and fracture is increased among older people with HIV. We compared the effects of low (1000 IU) vs moderate (3000 IU) vitamin D3 (VitD) supplementation on areal bone mineral density (aBMD) and volumetric bone mineral density (vBMD) in African American and Hispanic postmenopausal women with HIV on antiretroviral therapy.

METHODS

We performed a 12-month prospective, randomized, double-blind, placebo-controlled study with primary outcomes of change in aBMD by dual-energy X-ray absorptiometry (DXA) and secondary outcomes of change in vBMD by quantitative computed tomography and bone turnover markers. An intent-to-treat analysis was performed on 85 randomized subjects (43 low and 42 moderate) for primary DXA outcomes, and complete case analysis was performed for secondary outcomes.

RESULTS

Mean age was 56 ± 5 years, median CD4 count was 722 cells/mm, and 74% had HIV RNA ≤ 50 copies/mL. Serum 25-OHD was higher in the moderate than low VitD group at 6 months (33.1 ± 10.3 vs 27.8 ± 8.1 ng/mL, P = 0.03) and 12 months, but parathyroid hormone levels remained similar. Percent change in aBMD, vBMD, and bone turnover markers did not differ between low and moderate VitD groups before or after adjustment for baseline aBMD.

CONCLUSIONS

VitD supplementation at 3000 IU daily increased mean total 25-OHD levels in postmenopausal women with HIV, but we did not find evidence of an effect on BMD beyond those observed with 1000 IU daily. Future studies are necessary to determine whether VitD supplementation is beneficial in this patient population, and if so, what dose is optimal for skeletal health.

Bone mass preservation with high-dose cholecalciferol and dietary calcium in HIV patients following antiretroviral therapy. Is it possible?

OBJECTIVE

To evaluate whether treatment with 100,000 IU/month (equivalent to 3200 IU/day) of cholecalciferol and 1 g/day of dietary calcium supplementation in HIV patients following different cART regimens yields normal levels of vitamin D3 and PTH as well as whether changes in bone mineral density are clinically significant.

METHODS

Consecutive HIV patients following different cART regimens received 100,000 IU/month (equivalent to 3200 IU/day) of cholecalciferol and 1 g/day of dietary calcium supplementation. The participants underwent BMD assessment via dual energy X-ray absorptiometry of the spine and hip at baseline (T0) and after 24 months (T1). Levels of 25(OH) vitamin D3 and parathyroid hormone (PTH) were assessed at T0 and T1. Quantitative variables were assessed with a paired t-test, independent t-test or analysis of variance, as appropriate. A chi-squared analysis was used to assess the association between qualitative variables. A p-value <0.05 was considered significant. Patients were divided into three groups depending on the cART regimen.

RESULTS

A total of 79 patients were included (40 males, 51% and 39 females, 49%), with a mean age of 46.6 (SD ±11.2) years, a baseline CD4 count of 649 cells/µl and a mean 25 hydroxycholecalciferol (25(OH) D3) value of 25 + 10 ng/ml. After 24 months, the 25(OH) D3 increased to 40 + 11 ng/ml. The initial BMDs at T0 were estimated as 0.919 (±0.27) and 0.867 (±0.14) g/cm² at the spine and hip, respectively. After 24 months, the BMD was 0.933 (±0.15) g/cm² at the spine and 0.857 (±0.14) g/cm² at the hip. Based on a BMD change exceeding 3%, a worsening was observed in 23% of patients at the spine and 27% at the hip, whereas stability or improvement was demonstrated in 77% of patients at the spine and 73% at the hip. Subgrouping patients based on antiretroviral therapy indicated that, at T1, there was a statistically significant increase in vitamin D3 concentration in all patients, while PTH concentration was not significantly reduced in patients taking tenofovir or efavirenz. BMD stability or improvement was demonstrated in 77% of patients at the spine and 73% at the hip after 24 months. The multivariate analysis confirms a decrease in vitamin D3 and an increase in PTH levels in smokers, as well higher vitamin D3 concentrations in males and lower spine BMDs in menopausal females.

CONCLUSION

The proposed protocol of cholecalciferol and dietary calcium supplementation is safe and valid for correcting vitamin D abnormalities in almost all patients as well as reducing PTH levels in a high percentage of patients; however, it is not sufficient for normalization, particularly in patients exposed to tenofovir or efavirenz. At the spine, no significant BMD change was found in any of the therapy groups. At the hip, our data confirm a modest negative effect on bone mass caused by tenofovir and efavirenz.

The impact of vitamin D supplementation on musculoskeletal health outcomes in children, adolescents, and young adults living with HIV: A systematic review

OBJECTIVE

HIV-positive children, adolescents, and young adults are at increased risk poor musculoskeletal outcomes. Increased incidence of vitamin D deficiency in youth living with HIV may further adversely affect musculoskeletal health. We investigated the impact of vitamin D supplementation on a range of musculoskeletal outcomes among individuals aged 0-25 years living with HIV.

METHODS

A systematic review was conducted using databases: PubMed/Medline, CINAHL, Web of Knowledge, and EMBASE. Interventional randomised control trials, quasi-experimental trials, and previous systematic reviews/meta-analyses were included. Outcomes included: BMD, BMC, fracture incidence, muscle strength, linear growth (height-for-age Z-score [HAZ]), and biochemical/endocrine biomarkers including bone turnover markers.

RESULTS

Of 497 records, 20 studies met inclusion criteria. Thirteen studies were conducted in North America, one in Asia, two in Europe, and four in Sub-Saharan Africa. High-dose vitamin D supplementation regimens (1,000-7,000 IU/day) were successful in achieving serum 25-hydroxyvitamin-D (25OHD) concentrations above study-defined thresholds. No improvements were observed in BMD, BMC, or in muscle power, force and strength; however, improvements in neuromuscular motor skills were demonstrated. HAZ was unaffected by low-dose (200-400 IU/day) supplementation. A single study found positive effects on HAZ with high-dose supplementation (7,000 vs 4,000IU/day).

CONCLUSIONS

Measured bone outcomes were unaffected by high-dose vitamin D supplementation, even when target 25OHD measurements were achieved. This may be due to: insufficient sample size, follow-up, intermittent dosing, non-standardised definitions of vitamin D deficiency, or heterogeneity of enrolment criteria pertaining to baseline vitamin D concentration. High-dose vitamin D may improve HAZ and neuromuscular motor skills. Adequately powered trials are needed in settings where HIV burden is greatest. PROSPERO Number: CRD42016042938.

Tenofovir disoproxil fumarate appears to disrupt the relationship of vitamin D and parathyroid hormone

BACKGROUND

Tenofovir disoproxil fumarate (TDF) increases serum parathyroid hormone (PTH) and 1,25 dihydroxy vitamin D (1,25-(OH)₂D), and decreases bone mineral density (BMD). Optimal treatment of TDF-associated BMD loss requires an understanding of the primary cause of these abnormalities.

METHODS

Secondary review of data from two studies of TDF use in youth, comparing the relationship of PTH, 25-hydroxy vitamin D (25-OHD) and 1,25-(OH)₂D in three groups with varying exposures to TDF: youth without HIV enrolled in a trial of TDF/emtricitabine (FTC) for HIV pre-exposure prophylaxis (PrEP) at baseline (no TDF exposure) and after 12 weeks of TDF (short-term TDF exposure); and youth with HIV treated with TDF-containing combination antiretroviral therapy (cART) for at least 6 months at study entry (long-term TDF exposure). Relationships were evaluated by correlation analyses.

RESULTS

Participants ranged in age from 17 to 24 years and >50% were Black/African American. In persons not treated with TDF, PTH had the physiologically appropriate negative correlation with 25-OHD (r=-0.3504, P=0.004). Correlations between PTH and 25-OHD in groups treated with TDF were weaker or absent. With longer term TDF treatment in persons with HIV, 25-OHD and 1,25-(OH)₂D had the positive correlation similar to that found in vitamin D deficiency.

CONCLUSIONS

TDF changes the relationship of 25-OHD to PTH, suggesting that in persons using TDF for PrEP or cART, a higher than usual target for serum 25-OHD concentration might be needed to reduce PTH and optimize bone health.

CLINICAL TRIALS REGISTRATION

NCT01751646 (ATN 109) and NCT01769469 (ATN 117).

Bone Health and Impact of Tenofovir Treatment in Men with Hepatitis-B Related Chronic Liver Disease

BACKGROUND

Chronic Liver Disease (CLD) has been shown to have an adverse impact on bone health. Hepatitis-B related CLD and its treatment with tenofovir may have additional effects on skeleton.

OBJECTIVE

To study the impact of HBV related CLD and its treatment with Tenofovir on bone health in Indian subjects.

METHODS

This cross sectional study included men (18-60 years) and comprised of three groups: Group-1 was treatment naïve HBV related CLD (n = 79), Group-2 those with HBV related CLD on tenofovir for at least 1 year (n = 136), Group-3 age, sex and Body Mass Index (BMI) matched healthy controls (n = 58). Bone biochemistry and Bone Mineral Density (BMD) at spine, Femoral Neck (FN) and forearm were studied. Independent t-test or ANOVA was used to compare the means of continuous variables and chi-square test for categorical variables. Multiple logistic regression was used to assess the factors causing Low Bone Mass (LBM) at FN.

RESULTS

A significantly greater proportion (P < 0.05) of patients (40%) with CLD (group 1 and group 2) had vitamin D deficiency (<20 ng/ml) in comparison with control group (22%). The mean serum C-Terminal telopeptide was significantly higher (P < 0.05) and the mean BMD was significantly lower (P < 0.05) in subjects with HBV related CLD than controls. The prevalence of LBM was higher in group 1 at the spine (31%) and forearm (18.4%) when compared to controls (8.1% and 7.8% respectively) (P < 0.05). The proportion of patients with LBM at FN was highest in group 2 (12.3%) compared to those in group 1 (8%) and group 3 (4%) (P < 0.05). Advanced age, low BMI, and high viral load (>10,000 IU/ml) emerged as significant risk factors for LBM at FN.

CONCLUSION

The impact of hepatitis-B related CLD as well as its treatment on bone health is significant. Bone health need to be periodically evaluated in these subjects especially in older men who are lean and have a higher viral load.

Bone turnover markers in HIV-infected women on tenofovir-based antiretroviral therapy

Background: Tenofovir disoproxil fumarate (TDF) antiretroviral therapy is associated with disruption of the bone turnover process.Objectives: The objective of this study was to determine the association between tenofovir (TFV) plasma concentration and various bone turnover markers and compare these markers in HIV-infected women and HIV-uninfected controls.Method: A cross-sectional sub-study included 30 HIV-infected women on TDF and 30 HIV-uninfected matched participants. Serum calcium (SrCa), serum phosphate (SrP), C-terminal telopeptide (CTx), parathyroid hormone (PTH), alkaline phosphatase (ALP), C-reactive protein (CRP), vitamin D (VitD) and bone mineral density (BMD) were measured. Plasma TFV was assayed on HPLC-MS/MS. The statistical tests applied were Mann–Whitney test, unpaired t-test, analysis of covariance, regression and correlation analysis.Results: In HIV-infected women, no correlation existed between plasma TFV concentration and CTx, PTH, ALP, SrCa, SrP, VitD or BMD (p > 0.05). After adjusting for smoking and alcohol use, ALP (p < 0.001), CTx (p = 0.027) and PTH (p = 0.050) were significantly higher in HIV-infected compared to HIV-uninfected women. Women with TFV concentration ≥ 120 ng/mL had higher PTH concentrations (p = 0.037) compared to those with ≤ 100 ng/mL. Significant correlations between SrCa and PTH and SrCa and SrP including CTx and PTH (p < 0.05) were present in HIV-uninfected women while absent in HIV-infected counterparts (p > 0.05).Conclusion: The results indicate possible increased bone turnover at higher TFV concentrations. The normal regular bone turnover processes in HIV-infected women on TDF therapy are altered. Larger studies are warranted to confirm these results.

Racial differences in calculated bioavailable vitamin D with vitamin D/calcium supplementation

OBJECTIVES

Some studies suggest that bioavailable 25-dihydroxyvitamin D [25-(OH)D] is more accurate than total 25-(OH)D as an assessment of vitamin D (VitD) status in black individuals. We hypothesized that increases in bioavailable 25-(OH)D would correlate better with improvement in bone outcomes among black HIV-infected adults.

DESIGN

This is a secondary analysis of AIDS Clinical Trials Group A5280, a randomized, double-blind study of VitD3 and calcium supplementation in HIV-infected participants initiating antiretroviral therapy.

METHODS

Effect of VitD/calcium on total and calculated bioavailable 25-(OH)D, parathyroid hormone, bone turnover markers, and bone mineral density in black and nonblack participants were evaluated at 48 weeks. Wilcoxon signed-rank tests and Wilcoxon rank sum tests assessed within and between-race differences.

RESULTS

Of 165 participants enrolled, 129 (40 black and 89 nonblack) had complete data. At baseline, black participants had lower total 25-(OH)D [median (Q1,Q3) 22.6 (15.8, 26.9) vs. 31.1 (23.1, 38.8) ng/ml, P < 0.001] but higher bioavailable 25-(OH)D [2.9 (1.5, 5.2) vs. 2.0 (1.5, 3.0) ng/ml, P = 0.022] than nonblack participants. After 48 weeks of VitD/calcium supplementation, bioavailable 25-(OH)D increased more in black than nonblack participants, but there were no between-race differences change in bone turnover markers or bone mineral density. The associations between increases in 25-(OH)D levels and change in bone outcomes appeared similar for both total and bioavailable 25-(OH)D.

CONCLUSION

Baseline and change in bioavailable 25-(OH)D were higher among black adults initiating antiretroviral therapy with VitD/calcium; however, associations between 25-(OH)D and bone outcomes appeared similar for total and bioavailable 25-(OH)D. The assessment of total 25-(OH)D may be sufficient for evaluation of VitD status in black HIV-infected individuals.

TRIAL REGISTRATION NUMBER

NCT01403051.

Tenofovir and bone health

PURPOSE OF REVIEW

With continued improvements to the antiviral efficacy and tolerability of antiretroviral therapy, long-term safety of antiretroviral therapy has become paramount. Low bone mineral density and fragility fractures are more common in HIV-infected individuals than in the general population. The aims of this review are to describe potential mechanisms underlying the adverse effects of tenofovir on bone, clinical studies of tenofovir disoproxil fumarate (TDF) and bone, and more recent bone data on tenofovir alafenamide.

RECENT FINDING

Several studies have demonstrated an approximately 1-3% greater bone mineral density loss with TDF compared with other agents. Recent studies with tenofovir alafenamide have shown improved bone (and renal) safety with similar virologic efficacy when compared to TDF.

SUMMARY

Given these findings, TDF-containing regimens may be gradually replaced with non-TDF containing regimens for the treatment of HIV infection, especially in those at higher risk for fragility fracture.

Decline in Bone Mass With Tenofovir Disoproxil Fumarate/Emtricitabine Is Associated With Hormonal Changes in the Absence of Renal Impairment When Used by HIV-Uninfected Adolescent Boys and Young Men for HIV Preexposure Prophylaxis

BACKGROUND

We aimed to define the relative importance of renal and endocrine changes in tenofovir disoproxil fumarate (TDF)-related bone toxicity.

METHODS

In a study of daily TDF/emtricitabine (FTC) preexposure prophylaxis (PrEP) in human immunodeficiency virus (HIV)-uninfected young men who have sex with men, we measured changes from baseline in blood and urine markers of the parathyroid hormone (PTH)-vitamin D-fibroblast growth factor 23 (FGF23) axis, creatinine, and renal tubular reabsorption of phosphate (TRP). We explored the relationship of those variables to changes in bone mineral density (BMD). Tenofovir-diphosphate (TFV-DP) in red blood cells was used to categorize participants into high and low drug exposure groups.

RESULTS

There were 101 participants, median age 20 years (range 15 to 22). Compared with low drug exposure, high-exposure participants showed increase from baseline in PTH and decline in FGF23 by study week 4, with no differences in creatinine, phosphate, or TRP. At 48 weeks, the median (interquartile range) percent decline in total hip BMD was greater in those with high- compared to low- exposure (-1.59 [2.77] vs +1.54 [3.34] %, respectively; P = .001); in high-exposure participants, this correlated with week 4 TFV-DP (inversely; r = -0.60, P = .002) and FGF23 (directly; r = 0.42; P = .039) but not other variables.

CONCLUSIONS

These findings support the short-term renal safety of TDF/FTC PrEP in HIV-seronegative young men and suggest that endocrine disruption (PTH-FGF23) is a primary contributor to TDF-associated BMD decline in this age group.

CLINICAL TRIALS REGISTRATION

NCT01769469.

Serum FGF23 levels may not be associated with serum phosphate and 1,25-dihydroxyvitamin D levels in patients with Fanconi syndrome-induced hypophosphatemia

Fibroblast growth factor 23 (FGF23) is regulated by sustained phosphate supplementation and restriction. However, few studies have investigated FGF23 levels in patients with Fanconi syndrome. Therefore, we evaluated intact and C-terminal FGF23 and FGF23-associated parameters in four patients with Fanconi syndrome. Serum intact and C-terminal FGF23 levels were extremely low. Although serum phosphate and 1,25-dihydroxyvitamin D levels improved to or above the normal range within 1 year of treatment with oral phosphate and calcitriol, serum FGF23 levels remained low. Serum FGF23 levels in patients with Fanconi syndrome might be regulated by novel factors other than serum phosphate and 1,25-dihydroxyvitamin D levels.

Longitudinal increase in vitamin D binding protein levels after initiation of tenofovir/lamivudine/efavirenz among individuals with HIV

OBJECTIVE

To examine longitudinal change in vitamin D binding protein (DBP) levels during the first year after initiation of tenofovir disoproxil fumarate (TDF)/lamivudine/efavirenz and compare these findings with concurrent changes in markers of skeletal metabolism.

DESIGN

Secondary analysis of plasma samples collected from an ongoing multicenter clinical trial.

METHODS

Plasma samples collected at 0, 24, and 48 weeks after initiation of TDF + lamivudine + efavirenz from 134 adult participants enrolled in a multicenter randomized trial were analyzed. Data regarding sociodemographic and clinical characteristics were obtained as part of the parent study. Laboratory analyses included plasma DBP, intact parathyroid hormone, total 25-hydroxy vitamin D, phosphorus, the bone resorption marker collagen type 1 cross-linked C-telopeptide, and the bone formation marker total procollagen type 1 N-terminal propeptide. Repeated measures analysis of variance was used to measure changes in biomarkers over time.

RESULTS

Our sample included 108 men and 26 women (mean age 33.6 ± 9.6 years). Median levels of DBP increased significantly from baseline to 48 weeks [154 (91.8-257.4) versus 198.3 (119.6-351.9) μg/ml, P < 0.001]. A concurrent rise in intact parathyroid hormone levels was observed over the same period [32.3 (24.4-40.9) versus 45.2 (35.1-60.4) pg/ml, P < 0.001]; however, 25-hydroxy vitamin D and phosphorus levels remained stable. Bone resorption and formation markers rapidly increased from 0 to 24 weeks, followed by a slight decline or plateau, but remained significantly elevated at 48 weeks (P < 0.001).

CONCLUSION

Our study provides longitudinal data supporting a potential role for DBP in bone loss associated with TDF-based therapy. Further research to elucidate the mechanistic pathways and clinical impact of these findings is warranted.

Once-daily maraviroc versus tenofovir/emtricitabine each combined with darunavir/ritonavir for initial HIV-1 treatment

Objective:

The aim of this study was to evaluate the efficacy of maraviroc along with darunavir/ritonavir, all once daily, for the treatment of antiretroviral-naive HIV-1 infected individuals.

Design:

MODERN was a multicentre, double-blind, noninferiority, phase III study in HIV-1 infected, antiretroviral-naive adults with plasma HIV-1 RNA at least 1000 copies/ml and no evidence of reduced susceptibility to study drugs.

Methods:

At screening, participants were randomized 1 : 1 to undergo either genotypic or phenotypic tropism testing. Participants with CCR5-tropic HIV-1 were randomized 1 : 1 to receive maraviroc 150 mg once daily or tenofovir/emtricitabine once daily each with darunavir/ritonavir once daily for 96 weeks. The primary endpoint was the proportion of participants with HIV-1 RNA less than 50 copies/ml (Food and Drug Administration snapshot algorithm) at Week 48. A substudy evaluated bone mineral density, body fat distribution and serum bone turnover markers.

Results:

Seven hundred and ninety-seven participants were dosed (maraviroc, n = 396; tenofovir/emtricitabine, n = 401). The Data Monitoring Committee recommended early study termination due to inferior efficacy in the maraviroc group. At Week 48, the proportion of participants with HIV-1 RNA less than 50 copies/ml was 77.3% for maraviroc and 86.8% for tenofovir/emtricitabine [difference of −9.54% (95% confidence interval: −14.83 to −4.24)]. More maraviroc participants discontinued for lack of efficacy, which was not associated with non-R5 tropism or resistance. Discontinuations for adverse events, Category C events, Grade 3/4 adverse events and laboratory abnormalities were similar between groups.

Conclusion:

A once-daily nucleos(t)ide-sparing two-drug regimen of maraviroc and darunavir/ritonavir was inferior to a three-drug regimen of tenofovir/emtricitabine and darunavir/ritonavir in antiretroviral-naive adults.

Associations between vitamin D metabolites, antiretroviral therapy and bone mineral density in people with HIV

RATIONALE

To see if vitamin D and antiretroviral therapy are associated with bone mineral density (BMD) in people with HIV.

RESULT

Lower hip BMD was associated with tenofovir (an antiretroviral medicine) in those with 25(OH)D ≥50 nmol/L.

SIGNIFICANCE

The relationship between antiretroviral therapy and hip BMD differs depending on vitamin D status.

INTRODUCTION

People with HIV have an increased risk of low BMD and fractures. Antiretroviral therapy contributes to this increased risk. The aim of this study was to evaluate associations between vitamin D metabolites and antiretroviral therapy on BMD.

METHODS

The simplification of antiretroviral therapy with tenofovir-emtricitabine or abacavir-lamivudine trial (STEAL) was an open-label, prospective randomised non-inferiority study that compared simplification of current nucleoside reverse transcriptase inhibitors (NRTIs) to fixed-dose combination tenofovir-emtricitabine (TDF-FTC) or abacavir-lamivudine. Serum 25(OH)D and 1,25(OH)2D were measured in 160 individuals (90 receiving TDF-FTC, 70 receiving other NRTIs) at baseline from this study. Multivariable linear regression models were constructed to evaluate the covariates of 1,25(OH)2D and BMD.

RESULTS

Protease inhibitor use (p = 0.02) and higher body mass index (BMI) (p = 0.002) were associated with lower 1,25(OH)2D levels in those with 25(OH)D <50 nmol/L. However, TDF-FTC use (p = 0.01) was associated with higher 1,25(OH)2D levels, but only in those with 25(OH)D ≥50 nmol/L. White ethnicity (p = 0.02) and lower BMI (p < 0.001) in those with 25(OH)D <50 nmol/L and with TDF-FTC use (p = 0.008) in those with 25(OH)D ≥50 nmol/L were associated with lower hip BMD. TDF-FTC use, higher serum calcium and serum βCTX, winter, and lower bone-specific alkaline phosphatase (BALP) and BMI were associated with lower lumbar spine BMD.

CONCLUSION

TDF-FTC use (versus non-TDF-FTC use) was associated with lower hip BMD, and this difference was more pronounced in those with 25(OH)D ≥50 nmol/L. Serum 25(OH)D <50 nmol/L was associated with lower hip BMD in all participants. Therefore, the associations between antiretroviral therapy and hip BMD differ depending on vitamin D status.

Validation and Application of a Liquid Chromatography-Tandem Mass Spectrometry Method To Determine the Concentrations of Sofosbuvir Anabolites in Cells

Sofosbuvir (SOF) is a highly efficacious and well-tolerated uridine nucleotide analog that inhibits the hepatitis C virus (HCV) NS5B polymerase enzyme. SOF is administered as a prodrug, which undergoes intracellular phosphorylation by host enzymes to a monophosphate, diphosphate, and finally a pharmacologically active triphosphate. In order to fully understand the clinical pharmacology of SOF, there is a great need to determine the intracellular phosphate concentrations of the drug. We describe the validation and utilization of a method to characterize SOF's disposition into various in vivo cell types, including hepatocytes, peripheral blood mononuclear cells (PBMC), and red blood cells (RBC). Standard bioanalytical validation criteria were applied to lysed cellular matrices, with a validated linear range of 50 to 50,000 fmol/sample for each phosphate moiety. The assay was utilized to collect the first data demonstrating concentrations of phosphorylated anabolites formed in PBMC, hepatocytes, and RBC in vivo during SOF therapy. Median concentrations in PBMC were 220 (range, 51.5 to 846), 70.2 (range, 25.8 to 275), and 859 (range, 54.5 to 6,756) fmol/10(6) cells in the monophosphate, diphosphate, and triphosphate fractions, respectively. In contrast, RBC triphosphate concentrations were much lower than those of PBMC, as the median concentration was 2.91 (range, 1.14 to 10.4) fmol/10(6) cells. The PBMC triphosphate half-life was estimated at 26 h using noncompartmental approaches, while nonlinear mixed-effect modeling was used to estimate a 69 h half-life for this moiety in RBC. The validated method and the data it generates provide novel insight into the cellular disposition of SOF and its phosphorylated anabolites in vivo.

Fibroblast growth factor 23: associations with antiretroviral therapy in patients co-infected with HIV and hepatitis C

OBJECTIVES

Fibroblast growth factor 23 (FGF23) has been associated with cardiovascular mortality. We estimate associations between the level of plasma FGF23 and exposure to abacavir (ABC) and to other components of antiretroviral therapy in patients co-infected with HIV and hepatitis C.

METHODS

Both intact and c-terminal FGF23 were measured in plasma using commercial assays for a sub-cohort of 295 patients selected at random from the 1150 patients enrolled in the Canadian Co-infection Cohort. The multiplicative effects of antiretroviral drug exposures and covariates on median FGF23 were then estimated using a hierarchical Bayesian model.

RESULTS

The median level of intact FGF23 was independent of either past or recent exposure to abacavir, with multiplicative ratios of 1.00 and 1.07, 95% credible intervals 0.90-1.12 and 0.94-1.23, respectively. Median intact FGF23 tended to increase with past use of both nonnucleoside reverse-transcriptase inhibitors and protease inhibitors, but tended to decrease with recent use of either tenofovir, efavirenz or lopinavir. There were no obvious associations between the median level of c-terminal FGF23 and individual drugs or drug classes. Age, female gender, smoking and the aspartate aminotransferase to platelet ratio index were all associated with a higher median c-terminal FGF23 but not with a higher median intact FGF23.

CONCLUSIONS

The level of FGF23 in plasma was independent of exposure to ABC. Lower levels of intact FGF23 with recent use of tenofovir, efavirenz or lopinavir may reflect their adverse effects on bone and vitamin D metabolism relative to other drugs in their respective drug classes.

Vitamin D and Calcium Attenuate Bone Loss With Antiretroviral Therapy Initiation: A Randomized Trial

BACKGROUND

Antiretroviral therapy initiation for HIV-1 infection is associated with 2% to 6% loss of bone mineral density (BMD).

OBJECTIVE

To evaluate the effect of vitamin D3 plus calcium supplementation on bone loss associated with antiretroviral therapy initiation.

DESIGN

48-week prospective, randomized, double-blind, placebo-controlled study. (ClinicalTrials.gov: NCT01403051).

SETTING

39 AIDS Clinical Trials Group units.

PATIENTS

Adults with antiretroviral therapy-naive HIV.

MEASUREMENTS

BMD by dual-energy x-ray absorptiometry, 25-hydroxyvitamin D levels, and other laboratory assessments.

RESULTS

165 eligible patients were randomly assigned (79 received vitamin D3 plus calcium and 86 received placebo). The study groups were well-balanced at baseline: 90% were men, 33% were non-Hispanic black, and the median CD4 count was 0.341 × 109 cells/L. At 48 weeks, the percentage of decline in total hip BMD was smaller in the vitamin D3 plus calcium group than in the placebo group: Medians were -1.36% (interquartile range [IQR], -3.43% to 0.50%) and -3.22% (IQR, -5.56% to -0.88%), respectively (P = 0.004). Similar results were seen at the lumbar spine. At 48 weeks, 90% of patients achieved HIV-1 RNA levels less than 50 copies/mL. Levels of 25-hydroxyvitamin D3 increased with vitamin D3 plus calcium but not with placebo: Median change was 61.2 nmol/L (IQR, 36.4 to 94.3) versus 1.7 nmol/L (IQR, -13.2 to 10.7) (P < 0.001). Overall, 103 patients (62%) reported 1 or more adverse event, with similar distribution between groups; no cases of hypercalcemia and 1 case of nephrolithiasis were reported in the placebo group.

LIMITATION

No international sites were included, and follow-up was only 48 weeks.

CONCLUSION

Vitamin D3 plus calcium supplementation mitigates the BMD loss seen with initiation of efavirenz/emtricitabine/tenofovir disoproxil fumarate.

Less Bone Loss With Maraviroc- Versus Tenofovir-Containing Antiretroviral Therapy in the AIDS Clinical Trials Group A5303 Study

BACKGROUND

There is a need to prevent or minimize bone loss associated with antiretroviral treatment (ART) initiation. We compared maraviroc (MVC)- to tenofovir disoproxil fumarate (TDF)-containing ART.

METHODS

This was a double-blind, placebo-controlled trial. ART-naive subjects with human immunodeficiency virus type 1 RNA load (viral load [VL]) >1000 copies/mL and R5 tropism were randomized to MVC 150 mg or TDF 300 mg once daily (1:1), stratified by VL <100 000 or ≥100 000 copies/mL and age <30 or ≥30 years. All subjects received darunavir 800 mg, ritonavir 100 mg, and emtricitabine 200 mg daily. Dual-energy X-ray absorptiometry scanning was done at baseline and week 48. The primary endpoint was percentage change in total hip bone mineral density (BMD) from baseline to week 48 in the as-treated population.

RESULTS

We enrolled 262 subjects. A total of 259 subjects (130 MVC, 129 TDF) contributed to the analyses (91% male; median age, 33 years; 45% white, 30% black, 22% Hispanic). Baseline median VL was 4.5 log10 copies/mL and CD4 count was 390 cells/µL. The decline in hip BMD (n = 115 for MVC, n = 109 for TDF) at week 48 was less with MVC (median [Q1, Q3] of -1.51% [-2.93%, -0.11%] vs -2.40% [-4.30%, -1.32%] for TDF (P < .001). Lumbar spine BMD decline was also less with MVC (median -0.88% vs -2.35%; P < .001). Similar proportions of subjects in both arms achieved VL ≤50 copies/mL in as-treated and ITT analyses.

CONCLUSIONS

MVC was associated with less bone loss at the hip and lumbar spine compared with TDF. MVC may be an option to attenuate ART-associated bone loss.

CLINICAL TRIALS REGISTRATION

NCT01400412.

Antiretroviral therapy: current drugs

The rapid advances in drug discovery and the development of antiretroviral therapy is unprecedented in the history of modern medicine. The administration of chronic combination antiretroviral therapy targeting different stages of the human immunodeficiency virus' replicative life cycle allows for durable and maximal suppression of plasma viremia. This suppression has resulted in dramatic improvement of patient survival. This article reviews the history of antiretroviral drug development and discusses the clinical pharmacology, efficacy, and toxicities of the antiretroviral agents most commonly used in clinical practice to date.

Increased bone resorption during tenofovir plus lopinavir/ritonavir therapy in Chinese individuals with HIV

We sought to evaluate the effects of antiretroviral therapy on skeletal metabolism in Chinese individuals with human immunodeficiency virus. Patients switched to tenofovir/lamivudine + lopinavir/ritonavir after treatment failure had an increase in bone resorption marker levels by nearly 60%, which is greater than the magnitude previously described in non-Chinese populations.

INTRODUCTION

Few studies have evaluated the effects of antiretroviral therapy on skeletal metabolism in Asian populations infected with human immunodeficiency virus (HIV).

METHODS

We performed a secondary analysis of bone turnover markers (BTM) at baseline and 2 years in stored plasma samples collected from 2/2009 to 1/2013 as part of a multi-center trial. Two groups were compared: (1) treatment-naïve patients initiated on zidovudine (AZT)/lamivudine (3TC) plus nevirapine (NVP) and (2) patients who failed first-line therapy and were switched to tenofovir (TDF)/3TC plus lopinavir/ritonavir (LPVr). Tests included the bone resorption marker, C-terminal cross-linking telopeptide of type-1 collagen (CTX), and the bone formation marker procollagen type 1 N-terminal propeptide (P1NP).

RESULTS

In the TDF/3TC + LPVr group, samples were available from 59 patients at baseline and 56 patients at 2 years. Of these, 36 patients had samples available from both time points. In the AZT/3TC + NVP group, plasma samples were analyzed from 82 participants at baseline and of those, 61 had samples at 2 years. Median change over 2 years was greater in the TDF/3TC + LPVr group for both CTX (+0.24 ng/mL, interquartile ranges (IQR) 0.10-0.43 vs. +0.09 ng/mL, IQR -0.03 to 0.18, p = 0.001) and P1NP (+25.5 ng/mL, IQR 2.4-51.3 vs. +7.11 ng/mL, IQR -4.3 to 21.6, p = 0.012). Differences remained after adjusting for potential confounders in the multivariable analysis.

CONCLUSIONS

Switching to TDF/3TC + LPVr after treatment failure resulted in greater increases in BTMs than initiation with AZT/3TC + NVP in Chinese patients with HIV. Following this change, bone resorption marker levels increased by nearly 60 %, which is greater than the 25-35% increase from baseline described previously in non-Chinese populations. Further studies are warranted to elucidate these findings.

Bone alterations associated with HIV

HIV infection and initiation of antiretroviral therapy (ART) have been consistently associated with decreased bone mineral density (BMD), with growing evidence linking HIV to an increased risk of fracture. This is especially concerning with the expanding number of older persons living with HIV. Interestingly, recent data suggest that HIV-infected children and youth fail to achieve peak BMD, possibly increasing their lifetime risk of fracture. Elucidating the causes of the bone changes in HIV-positive persons is challenging because of the multifactorial nature of bone disease in HIV, including contribution of the virus, immunosuppression, ART toxicity, and traditional osteoporosis risk factors, such as age, lower weight, tobacco, and alcohol use. Thus, practitioners must recognize the risk of low BMD and fractures and appropriately screen patients for osteoporosis if risk factors exist. If fractures do occur or elevated fracture risk is detected through screening, treatment with bisphosphonate medications appears safe and effective in the HIV+population.

Vitamin D Binding Protein Impact on 25-Hydroxyvitamin D Levels under Different Physiologic and Pathologic Conditions

There is a high prevalence of vitamin D deficiency worldwide, but how to define vitamin D deficiency is controversial. Currently, the plasma concentration of total 25-hydroxyvitamin D [25(OH)D] is considered an indicator of vitamin D status. The free hormone hypothesis states that protein-bound hormones are inactive while unbound hormones are free to exert biological activity. The majority of circulating 25(OH)D and 1,25(OH)2D is tightly bound to vitamin D binding protein (DBP), 10-15% is bound to albumin, and less than 1% of circulating vitamin D exists in an unbound form. While DBP is relatively stable in most healthy populations, a recent study showed that there are gene polymorphisms associated with race and ethnicity that could alter DBP levels and binding affinity. Furthermore, in some clinical situations, total vitamin D levels are altered and knowing whether DBP is also altered may have treatment implications. The aim of this review is to assess DBP concentration in different physiological and pathophysiological conditions. We suggest that DBP should be considered in the interpretation of 25(OH)D levels.

Vitamin D3 supplementation increases fibroblast growth factor-23 in HIV-infected youths treated with tenofovir disoproxil fumarate

BACKGROUND

Tenofovir (TDF) is associated with phosphaturia and elevated 1,25 dihydroxy vitamin D (1,25-OH(2)D). Fibroblast growth factor 23 (FGF23) causes phosphaturia and increases in response to elevated 1,25-OH(2)D. Vitamin D-binding protein (VDBP) binds to 1,25-OH(2)D, decreasing its biological activity, and is elevated in individuals with higher plasma tenofovir concentrations. We compared FGF23 and VDBP before and after vitamin D3 (VITD) supplementation in youths treated with combination antiretroviral therapy (cART) containing or not containing TDF.

METHODS

A randomized controlled trial in HIV-positive youths aged 18-25 years enrolled participants based on cART treatment with TDF (TDF; n=118) or without TDF (no-TDF; n=85), and randomized within those groups to VITD (50,000 IU every 4 weeks) or placebo (PL). We measured FGF23 and VDBP and calculated free 1,25-OH(2)D at baseline and week 12, and compared changes by TDF treatment and VITD randomized group.

RESULTS

At baseline, serum FGF23 concentration showed a quadratic relationship with 1,25-OH(2)D most pronounced in the TDF group. At week 12, total and free 1,25-OH(2)D increased in the VITD but not PL groups, independent of TDF use. FGF23 increased in the TDF group receiving VITD, but there was no FGF23 change in the no-TDF group receiving VITD or the PL groups. The adjusted mean change in FGF23 from baseline to week 12 was 7.7 pg/ml in the TDF/VITD group, compared with -1.7 (no-TDF/VITD, P=0.010), -1.3 (TDF/PL, P=0.006) and 1.1 (no-TDF/PL, P=0.035).

CONCLUSIONS

These results suggest that TDF-containing cART may alter the FGF23 response to vitamin D supplementation in HIV-infected youths. Clinical trials number: NCT00490412.