Demographic and Clinical Characteristics of Persons with HIV with Viral Load:Adherence Mismatch Who Are at Risk of Future Viremia.

The potency of modern antiretroviral therapy (ART) allows for greater forgiveness to missed doses while still achieving, and maintaining, viral suppression. However, imperfect ART adherence, even if sufficient to maintain viral suppression, has been associated with adverse clinical outcomes. ART adherence can be objectively quantified using tenofovir diphosphate (TFV-DP) in dried blood spots (DBS), a biomarker of cumulative adherence that is predictive of future viremia-even among persons with HIV (PWH) with an undetectable HIV viral load (VL). Within a prospective cohort of PWH on tenofovir disoproxil fumarate-including ART, mismatch between drug concentration and HIV VL (i.e., low concentrations of TFV-DP in DBS in the setting of viral suppression with subsequent viremia at the following visit) was observed more frequently in PWH who were Black (36% vs. 15%; p = .04), had body mass index >30 kg/m2 (40% vs. 13%; p = .01), and reported <100% 3 months (68% vs. 50%; p = .005) and 30 days (56% vs. 31%; p = .001) adherence, compared with PWH without mismatch. Identifying PWH at risk for future viremia could help clinicians implement targeted timely interventions before episodes of breakthrough viremia.

Cumulative tenofovir diphosphate exposure in persons with HIV taking single- vs. multiple-tablet regimens.

BACKGROUND: We assessed cumulative antiretroviral exposure-using tenofovir diphosphate (TFV-DP) in dried blood spots (DBS)-in persons with HIV (PWH) receiving tenofovir disoproxil fumarate (TDF)-based antiretroviral therapy (ART) as single-tablet regimens (STR) or multiple-tablet regimens (MTR). METHODS: Blood for DBS was prospectively collected in PWH on TDF during 1144 person visits (n = 523). Linear mixed-effects models, adjusted for baseline characteristics, were used to compare TFV-DP in STR versus MTR. Models adjusted for ART regimen using either anchor drug class, pharmacokinetic booster status (unboosted [u/] or boosted [b/]), or a combined STR/MTR and booster categorical variable. RESULTS: In the anchor class-adjusted model, STR had 19% (95% confidence interval [CI]: 3%-37%; p = 0.02) higher TFV-DP concentrations than MTR. However, in the booster-adjusted model, STR was not significantly higher than MTR (estimate 5%, 95% CI: -9% to 21%; p = 0.48), although PWH on b/ART had 35% (95% CI: 16%-58%; p = 0.0001) higher TFV-DP than u/ART. In the STR/MTR-boosted variable model, when compared to u/MTR, b/STR, b/MTR, and u/STR had 25% (95% CI: 7%-47%; p = 0.005), 37% (95% CI: 17%-59%; p < 0.0001), and 7% (95% CI: -7% to 24%; p = 0.34) higher TFV-DP, respectively. Compared with b/MTR, b/STR had 9% (95% CI: -31% to 10%; p = 0.37) lower TFV-DP. In a sensitivity analysis of PWH with HIV viral load <20 copies/ml at all visits, b/STR and b/MTR had 34% (95% CI: 16%-55%; p < 0.0001) and 12% (95% CI: -2% to 27%; p = 0.09) higher TFV-DP, respectively, compared with u/MTR, while u/STR had 4% (95% CI: -15% to 8%; p = 0.50) lower TFV-DP. Compared with b/MTR, b/STR had 17% (95% CI: 2%-30%; p = 0.03) higher TFV-DP. CONCLUSIONS: Persons with HIV on b/TDF-based ART had higher TFV-DP than u/ART, regardless of STR or MTR use. No significant differences in TFV-DP between regimens of the same boosting status (i.e., b/STR vs. b/MTR; u/STR vs. u/MTR) were observed in the full cohort. Future research should examine the clinical utility of these findings in patient-tailored ART selection.

Low-Level Viremia Is Associated With Cumulative Adherence to Antiretroviral Therapy in Persons With HIV.

The drivers of low-level viremia (LLV) between 20 and 200 copies/mL remain unclear. In 1042 person-visits from 497 persons with HIV on tenofovir disoproxil fumarate-containing antiretroviral therapy (ART), the association between LLV and cumulative antiretroviral adherence (quantified using tenofovir diphosphate [TFV-DP] in dried blood spots) was assessed. Lower TFV-DP levels were associated with higher odds of LLV. As TFV-DP (fmol/punch) categories decreased from >1650 to 800-1650; 800-1650 to <800; and >1650 to <800, the adjusted odds ratios for LLV vs HIV VL <20 copies/mL were 2.0 (95% CI, 1.2-3.1), 2.4 (95% CI, 1.1-5.0), and 4.6 (95% CI, 2.2-9.9), respectively. This suggests that adherence could impact LLV.

Emtricitabine triphosphate in dried blood spots predicts future viremia in persons with HIV and identifies mismatch with self-reported adherence.

OBJECTIVE: Emtricitabine triphosphate (FTC-TP) in dried blood spots (DBS), a measure of short-term antiretroviral therapy (ART) adherence, is associated with viral suppression in persons with HIV (PWH). However, its ability to predict future viremia remains unknown. DESIGN: Prospective, observational cohort (up to three visits in 48 weeks). METHODS: PWH receiving TDF/FTC-based ART had DBS and HIV viral load obtained at routine clinical visits. FTC-TP in DBS was dichotomized into quantifiable vs. below the limit of quantification (BLQ). The adjusted odds ratio (aOR) of future viremia (≥20 copies/ml at next study visit) was estimated according to FTC-TP at the current visit. To assess for possible interactions, additional models adjusted for tenofovir diphosphate (TFV-DP) in DBS and 3-day self-reported adherence. RESULTS: Data from 433 PWH (677 paired DBS/HIV viral load samples) were analyzed. The aOR [95% confidence interval (CI)] for future viremia for BLQ vs. quantifiable FTC-TP was 3.4 (1.8--6.5; P = 0.0002). This diminished after adjusting for TFV-DP [aOR 1.9 (0.9--4.1); P = 0.090]. Among PWH reporting 100% 3-day adherence, the odds of future viremia were 6.0 times higher [(1.8--20.3); P = 0.001] when FTC-TP was BLQ vs. quantifiable. Among participants (n = 75) reporting less than 100% adherence, BLQ FTC-TP in DBS was not predictive of future viremia [aOR 1.3 (0.4--4.6); P = 0.96]. CONCLUSION: Nonquantifiable FTC-TP in DBS predicts future viremia and is particularly informative in PWH reporting perfect adherence. As point-of-care adherence measures become available, mismatches between objective and subjective measures, such as FTC-TP in DBS and self-report, could help clinicians identify individuals at an increased risk of future viremia.

Higher medication complexity in persons with HIV is associated with lower tenofovir diphosphate in dried blood spots.

STUDY OBJECTIVE: To assess the association between tenofovir diphosphate (TFV-DP) in dried blood spots (DBS), a measure of cumulative tenofovir-based antiretroviral (ART) adherence, with medication regimen complexity in persons with human immunodeficiency virus (PWH). DESIGN: Prospective clinical cohort (up to three visits over 48 weeks). SETTING: Academic-based HIV clinic. PATIENTS: PWH receiving tenofovir disoproxil fumarate (TDF)-based ART. MEASUREMENTS: DBS for TFV-DP were collected at every study visit. Baseline patient-level medication regimen complexity index (pMRCI) scores were calculated and categorized into three sub-scores (disease-specific [ART], non-ART, and over-the-counter [OTC]). The pMRCI scores were evaluated to assess the association with TFV-DP in DBS <350 fmol/punch after adjusting for clinical covariates. pMRCI scores were also categorized to estimate the adjusted relative risk (aRR) of having a TFV-DP <350 fmol/punch between pMRCI quartiles. MAIN RESULTS: Data from 525 participants (1,146 person-visits) were analyzed. Baseline median (interquartile range [IQR]) pMRCI scores for participants with TFV-DP in DBS <350 vs. ≥350 fmol/punch were 4 (3, 8) vs. 4 (2, 6) for ART, 27 (12, 31) vs. 12 (5, 22) for non-ART, and 0 (0, 1) vs. 0 (0, 2) for OTC, respectively. For the non-ART scores, the aRR for having a TFV-DP in DBS <350 fmol/punch was 6.4 (95% CI: 2.0, 20.6; P=0.002) when comparing participants in the highest pMRCI quartile with those in the lowest quartile. CONCLUSIONS: Higher pMRCI for non-ART medications is associated with lower adherence as measured by TFV-DP in DBS. Future research should investigate whether reducing non-ART medication complexity improves ART adherence and exposure in PWH.

Lower Cumulative Antiretroviral Exposure in People Living With HIV and Diabetes Mellitus.

OBJECTIVE: People living with HIV (PLWH) are living longer and developing more non-AIDS comorbidities, which negatively impact antiretroviral therapy (ART) adherence. Tenofovir diphosphate (TFV-DP) in dried blood spots (DBS) is a novel pharmacologic measure of cumulative ART adherence that is predictive of viral suppression and future viremia. However, the relationship between non-AIDS comorbidities and this adherence measure is unknown. We aimed to evaluate the association between 3 non-AIDS comorbidities (diabetes mellitus (DM), hypertension, and hyperlipidemia) and TFV-DP in DBS in PLWH. METHODS: Blood for TFV-DP in DBS and HIV viral load was prospectively collected from PLWH on tenofovir disoproxil fumarate for up to 3 times over 48 weeks. Non-AIDS comorbidities were recorded. Mixed effect multivariable linear regression models were used to estimate the changes in TFV-DP concentrations in DBS according to the presence of comorbidities and to estimate the percent differences in TFV-DP concentrations between these groups. RESULTS: A total of 1144 person-visits derived from 523 participants with available concentrations of TFV-DP in DBS were included in this analysis. In univariate analysis, no significant association between non-AIDS comorbidities (categorized as having 0, 1, 2, or 3 comorbidities) and the concentrations of TFV-DP in DBS was observed (P = 0.40). Participants who had DM had 25% lower (95% confidence interval: -36% to -12%; P < 0.001) TFV-DP in DBS than participants without DM after adjusting for age, gender, race, body mass index, estimated glomerular filtration rate, CD4 T-cell count, hematocrit, ART class, patient-level medication regimen complexity index, and 3-month self-reported adherence. CONCLUSIONS: Diabetic PLWH have lower concentrations of TFV-DP in DBS compared with those without DM. Further research is required to identify the clinical implications and biological mechanisms underlying these findings.

Income Inequality Is Associated With Low Cumulative Antiretroviral Adherence in Persons With Human Immunodeficiency Virus.

BACKGROUND: The adherence biomarker tenofovir diphosphate (TFV-DP) in dried blood spots (DBS) is associated with viral suppression and predicts future viremia. However, its association with social determinants of health (SDoH) in people with human immunodeficiency virus (PWH) remains unknown. METHODS: Dried blood spots for TFV-DP were longitudinally collected from a clinical cohort of PWH receiving tenofovir disoproxil fumarate-based therapy (up to 3 visits over 48 weeks) residing in 5 Colorado counties. To assign SDoH, zip codes at enrollment were matched with SDoH data from AIDSVu (https://aidsvu.org/). The SDoH included household income, percentage living in poverty, education level, and income inequality (quantified using Gini coefficient, where 0 and 1 represent perfect income equality and inequality, respectively). Log-transformed TFV-DP concentrations were analyzed using a mixed-effects model to estimate percentage change (95% confidence interval) in TFV-DP for every significant change in the SDoH and adjusted for relevant covariates including age, gender, race, estimated glomerular filtration rate, body mass index, hematocrit, CD4+ T-cell count, antiretroviral drug class, and 3-month self-reported adherence. RESULTS: Data from 430 PWH totaling 950 person-visits were analyzed. In an adjusted analysis, income inequality was inversely associated with TFV-DP in DBS. For every 0.1 increase in the Gini coefficient, TFV-DP concentrations decreased by 9.2% (-0.5 to -17.1; P = .039). This remained significant after adjusting for human immunodeficiency virus viral suppression, where a 0.1 increase in Gini was associated with a decrease of 8.7% (-0.3 to -17.9; P = .042) in TFV-DP. CONCLUSIONS: Higher income inequality was associated with lower cumulative antiretroviral adherence. These findings support the need for further research on how SDoH impact adherence and clinical care.

Factors associated with tenofovir diphosphate concentrations in dried blood spots in persons living with HIV.

OBJECTIVES: To determine factors associated with interindividual variability in tenofovir diphosphate (TFV-DP) concentrations in dried blood spots (DBSs) among persons living with HIV (PLWH). METHODS: PLWH who were at least 18 years old and taking tenofovir disoproxil fumarate-containing ART were prospectively recruited and enrolled from a clinical cohort and followed longitudinally (up to three visits over 48 weeks). With log-transformed TFV-DP concentrations in DBSs as the outcome, mixed-model regression analyses were used to assess associations between self-reported 3 month ART adherence, race and other clinical covariates (gender, age, BMI, CD4+ T cell count, estimated glomerular filtration rate, haematocrit, duration on current ART and anchor drug class) on TFV-DP in DBSs. RESULTS: Five hundred and twenty-seven participants (1150 person-visits) were analysed. Adjusting for race and other clinical covariates, every 10% increase in self-reported 3 month ART adherence was associated with an average TFV-DP concentration increase in DBSs of 28% (95% CI: 24%-32%; P < 0.0001). In the same model, female participants had 20% (95% CI: 3%-40%; P = 0.02) higher TFV-DP concentrations in DBSs, compared with male participants, and every 1 kg/m2 increase in BMI was associated with a decrease in TFV-DP concentration in DBSs by 2% (95% CI: -3% to -1%; P < 0.0001). CONCLUSIONS: Individual patient characteristics were predictive of TFV-DP concentration in DBSs in PLWH receiving tenofovir disoproxil fumarate-based ART. Future research to incorporate these predictors into the interpretation of this ART adherence biomarker, and to establish whether these associations extend to PLWH taking tenofovir alafenamide-containing ART, is needed.

Short Communication: Cascade of Antiretroviral Therapy Adherence in Virologically Suppressed Persons Living with HIV.

Variable adherence to antiretroviral therapy (ART) can maintain HIV viral suppression, but our understanding of the ART adherence continuum remains limited. In a clinical cohort of adult persons living with HIV treated with a tenofovir (TFV) disoproxil fumarate/emtricitabine (TDF/FTC)-based regimen, data on 3-month self-reported adherence and dried blood spots (DBS) for TFV diphosphate (TFV-DP) and FTC triphosphate (FTC-TP) were collected. Among 521 participants in whom DBS were available upon enrollment, 333 were virologically suppressed (<20 copies/mL). Only 145 (44%) of them reported 100% 3-month adherence, and 69 (21%) had drug concentrations in the highest adherence categories (TFV-DP ≥1,850 fmol/punch and quantifiable FTC-TP). These findings demonstrate a wide range of ART adherence and drug exposure associated with viral suppression, indicating that modern regimens are pharmacologically forgiving. Additional research is needed to understand the biologic effects of variable adherence and drug exposure beyond plasma virologic suppression.

Moderately High Tenofovir Diphosphate in Dried Blood Spots Indicates Drug Resistance in Viremic Persons Living with HIV.

BACKGROUND: Tenofovir diphosphate (TFV-DP) in dried blood spots (DBS) is a strong predictor of viral suppression in persons living with HIV (PLWH). Its association with antiretroviral therapy (ART) resistance remains unknown. METHODS: Blood was collected in PLWH receiving TDF-containing ART enrolled in a 48-week study. Tenofovir diphosphate/emtricitabine triphosphate (FTC-TP) were quantified from the same sample as HIV viral load (VL) in PLWH who developed resistance within ≤12 months. RESULTS: The study enrolled 807 participants, of whom 10 had new resistance-conferring mutations. Among these, median (interquartile range) TFV-DP and HIV VL were 956 (407-1510) fmol/punch and 9840 (513-68,200) copies/mL, respectively. Five had quantifiable FTC-TP in DBS. Based on previously published data, a TFV-DP concentration of 956 fmol/punch would have an adjusted odds of virologic suppression of 32.8 versus TFV-DP <350 fmol/punch, making viremia of ∼10,000 copies/mL an unexpected outcome. CONCLUSION: Moderately high TFV-DP in DBS (700-1249 fmol/punch) in PLWH with high viremia suggest that antiretroviral drug resistance might be present.

Predictive Value of Tenofovir Diphosphate in Dried Blood Spots for Future Viremia in Persons Living With HIV.

BACKGROUND: Tenofovir diphosphate (TFV-DP) in dried blood spots (DBS) is associated with viral suppression in persons living with HIV (PLWH) taking tenofovir disoproxil fumarate (TDF). However, its value as a predictor of future viremia remained unknown. METHODS: Blood for plasma viral load (VL) and TFV-DP in DBS were collected (up to 3 visits within 48 weeks) in PLWH on TDF. TFV-DP cut points were selected using logistic prediction models maximizing the area under the receiver operation characteristic curve, and estimated adjusted odds ratio (aOR) of future viremia (≥20 copies/mL) were compared to the highest TFV-DP category. RESULTS: Among all 451 participants in the analysis, aOR of future viremia for participants with TFV-DP <800 and 800 to <1650 fmol/punch were 4.7 (95% CI, 2.6-8.7; P < .0001) and 2.1 (95% CI, 1.3-3.3; P = .002) versus ≥1650 fmol/punch, respectively. These remained significant for participants who were virologically suppressed at the time of the study visit (4.2; 95% CI, 1.5-12.0; P = .007 and 2.2; 95% CI, 1.2-4.0; P = .01). CONCLUSIONS: TFV-DP in DBS predicts future viremia in PLWH on TDF, even in those who are virologically suppressed. This highlights the utility of this biomarker to inform about adherence beyond VL. Clinical Trials Registration. NCT02012621.

Engagement in Mental Health Care is Associated with Higher Cumulative Drug Exposure and Adherence to Antiretroviral Therapy.

Mental health (MH) disorders are more prevalent among persons living with HIV compared to the general population, and may contribute to suboptimal adherence to antiretroviral therapy (ART). Tenofovir-diphosphate (TFV-DP), the phosphorylated anabolite of tenofovir (TFV), is a biomarker with a 17-day half-life in red blood cells. TFV-DP can be measured in dried blood spots (DBS) using liquid chromatography/tandem mass spectrometry (LC-MS/MS) to assess adherence and cumulative drug exposure to tenofovir disoproxil fumarate (TDF)-based ART. From a larger clinical cohort (N = 807), TFV-DP concentrations and a paired HIV viral load were available from 521 participants at their enrollment visit. We used multivariable linear regression to evaluate the association between TFV-DP in DBS and engagement in MH care. After adjusting for clinical covariates, participants with MH disorders who were engaged in MH care had 40% higher TFV-DP compared to participants with MH disorders who were not engaged in MH care (p < 0.001), and similar TFV-DP to participants without MH disorders (p = 0.219). Further research is needed to identify the mechanism(s) for these findings, with the goal of optimizing engagement and retention in MH care strategies to improve ART adherence and clinical outcomes in PLWH with MH disorders.

Emtricitabine triphosphate in dried blood spots is a predictor of viral suppression in HIV infection and reflects short-term adherence to antiretroviral therapy.

BACKGROUND: Emtricitabine triphosphate (FTC-TP), the phosphorylated anabolite of emtricitabine, can be quantified in dried blood spots (DBS). We evaluated FTC-TP in DBS as a predictor of viral suppression and evaluated self-reported adherence as a predictor of FTC-TP. METHODS: Persons living with HIV (PLWH) on an FTC-containing regimen were prospectively recruited. A DBS and HIV viral load were obtained during routine clinical visits. Self-reported adherence for 3 days, 30 days and 3 months was captured. Generalized estimating equations were used to estimate the adjusted odds ratio (aOR) of viral suppression for quantifiable FTC-TP versus below the limit of quantification (BLQ). The utility of self-reported adherence to predict quantifiable FTC-TP was assessed by calculating the area under receiver operating characteristic (ROC) curve. RESULTS: One thousand one hundred and fifty-four person-visits from 514 participants who had DBS assayed for FTC-TP were included in the analysis. After adjusting for age, gender, race, BMI, ART class, ART duration, estimated glomerular filtration rate and CD4+ T cell count, the aOR (95% CI) for viral suppression for quantifiable FTC-TP versus BLQ was 7.2 (4.3-12.0; P < 0.0001). After further adjusting for tenofovir diphosphate, the aOR was 2.1 (1.2-4.0; P < 0.015). The area under the ROC curve for 3 day self-reported adherence was 0.82 (95% CI 0.75-0.88) compared with 0.70 (95% CI 0.62-0.77, P = 0.004) and 0.79 (95% CI 0.71-0.86, P = 0.32) for 3 month and 30 day self-reported adherence, respectively. CONCLUSIONS: In PLWH, FTC-TP from DBS is a strong predictor of viral suppression, even after adjusting for tenofovir diphosphate, and was best predicted by 3 day self-reported adherence.

Tenofovir Diphosphate in Dried Blood Spots Is Strongly Associated With Viral Suppression in Individuals With Human Immunodeficiency Virus Infections.

BACKGROUND: Although tenofovir diphosphate (TFV-DP) in dried blood spots (DBS) is a predictor of adherence and pre-exposure prophylaxis efficacy, its utility in human immunodeficiency virus (HIV) treatment remains unknown. METHODS: DBS for TFV-DP were collected up to 3 times over 48 weeks in persons living with HIV (PLWH) who were receiving TFV disoproxil fumarate (TDF)-based therapy. Log-transformed baseline TFV-DP was compared using t-tests or analyses of variance; generalized estimating equations were used to estimate the adjusted odds ratio (aOR) of viral suppression (<20 copies/mL) based on the TFV-DP concentration at the study visit. RESULTS: We analyzed 1199 DBS from 532 participants (76 female; 101 Black, 101 Hispanic). Among the virologically-suppressed participants at baseline (n = 347), TFV-DP was lower in Blacks (geometric mean 1453, 95% confidence interval [CI] 1291-1635) vs Whites (1793, 95% CI 1678-1916; P = .002) and Hispanics (1760, 95% CI 1563-1982; P = .025); in non-boosted (1610, 95% CI 1505-1723) vs. boosted (1888, 95% CI 1749-2037; P = .002) regimens; and in non-nucleoside reverse transcription inhibitor-based (1563, 95% CI 1432-1707) vs. boosted protease inhibitor-based (1890, 95% CI 1704-2095; P = .006) and multiclass-based (1927, 95% CI 1650-2252; P = .022) regimens. The aOR of virologic suppression, after adjusting for age, gender, race, body mass index, estimated glomerular filtration rate, CD4+ T-cell count, antiretroviral drug class and duration of therapy, was 73.5 (95% CI 25.7-210.5; P < .0001) for a TFV-DP concentration ≥1850 fmol/punch compared to <350 fmol/punch. CONCLUSIONS: TFV-DP in DBS is strongly associated with virologic suppression in PLWH on TDF-based therapy and is associated with certain participant characteristics. Further research is required to evaluate this drug adherence and exposure measure in clinical practice. CLINICAL TRIALS REGISTRATION: NCT02012621.

Emtricitabine-Triphosphate in Dried Blood Spots as a Marker of Recent Dosing.

New objective measures of antiretroviral adherence are needed. We determined if emtricitabine triphosphate (FTC-TP) in dried blood spots (DBS) can be used as a marker of recent dosing with tenofovir disoproxil fumarate-emtricitabine (TDF-FTC). The half-life of FTC-TP was estimated in DBS samples obtained from an intensive pharmacokinetic (PK) study of coformulated TDF-FTC in HIV-negative and HIV-infected participants. The concordance of quantifiable FTC-TP in DBS with tenofovir (TFV)/FTC in plasma was evaluated by utilizing paired plasma-DBS samples from participants enrolled in 2 large preexposure prophylaxis (PrEP) open-label trials. The time to FTC-TP nondetectability after TDF-FTC dosing was evaluated utilizing DBS from HIV-negative participants enrolled in a directly observed therapy study of variable adherence to TDF-FTC. The mean (95% confidence interval [CI]) terminal half-life of FTC-TP in the PK study was 35 (23 to 47) h. A total of 143/163 (88%) samples obtained 0 to 48 h post-TDF-FTC dose had quantifiable FTC-TP in DBS, compared with 2/93 (2%) and 0/87 (0%) obtained >48 and >96 h postdose. In 746 paired plasma-DBS samples from 445 participants enrolled in PrEP trials, when both TFV/FTC in plasma were below the limit of quantification, FTC-TP was as well in 98.9% of the samples, and when either TFV or FTC in plasma was quantifiable, FTC-TP was as well in 90.5% of the samples. The half-life of FTC-TP in DBS is short relative to that of TFV-diphosphate (TFV-DP), making it a surrogate for TFV-FTC detection in plasma. FTC-TP can be quantified in DBS simultaneously with TFV-DP, which quantifies cumulative adherence to TDF-FTC. (The clinical trials discussed in this article have been registered at ClinicalTrials.gov under identifiers NCT01040091, NCT02022657, NCT00458393, NCT01772823, and NCT02012621.).

Pancreatic cancer organotypics: High throughput, preclinical models for pharmacological agent evaluation.

Pancreatic cancer carries a terrible prognosis, as the fourth most common cause of cancer death in the Western world. There is clearly a need for new therapies to treat this disease. One of the reasons no effective treatment has been developed in the past decade may in part, be explained by the diverse influences exerted by the tumour microenvironment. The tumour stroma cross-talk in pancreatic cancer can influence chemotherapy delivery and response rate. Thus, appropriate preclinical in vitro models which can bridge simple 2D in vitro cell based assays and complex in vivo models are required to understand the biology of pancreatic cancer. Here we discuss the evolution of 3D organotypic models, which recapitulare the morphological and functional features of pancreatic ductal adenocarcinoma (PDAC). Organotypic cultures are a valid high throughput preclinical in vitro model that maybe a useful tool to help establish new therapies for PDAC. A huge advantage of the organotypic model system is that any component of the model can be easily modulated in a short time-frame. This allows new therapies that can target the cancer, the stromal compartment or both to be tested in a model that mirrors the in vivo situation. A major challenge for the future is to expand the cellular composition of the organotypic model to further develop a system that mimics the PDAC environment more precisely. We discuss how this challenge is being met to increase our understanding of this terrible disease and develop novel therapies that can improve the prognosis for patients.

Molecular biology of pancreatic ductal adenocarcinoma.

PURPOSE OF REVIEW: Recent advances in sequencing technology have led to a deeper and more comprehensive understanding of the molecular biology of pancreatic ductal adenocarcinoma. This timely review seeks to summarize these recent advances which will provide a foundation for future studies in the field. RECENT FINDINGS: Stereotypical genetic alterations have been identified and confirmed. However, additional alterations have highlighted the importance and complexity of a number of intracellular signaling pathways that present unique opportunities for therapeutic targeting. SUMMARY: A genetic signature of pancreatic ductal adenocarcinoma has been identified. This recent and important work is currently in the process of being applied in many clinical applications from early diagnostics to customized therapeutic regimens for this disease. A fundamental understanding of these findings will thus be of utmost importance for future research in the field and in the clinical care of patients with this lethal disease.

The ins and outs of fibroblast growth factor receptor signalling.

FGFR (fibroblast growth factor receptor) signalling plays critical roles in embryogensis, adult physiology, tissue repair and many pathologies. Of particular interest over recent years, it has been implicated in a wide range of cancers, and concerted efforts are underway to target different aspects of FGFR signalling networks. A major focus has been identifying the canonical downstream signalling pathways in cancer cells, and these are now relatively well understood. In the present review, we focus on two distinct but emerging hot topics in FGF biology: its role in stromal cross-talk during cancer progression and the potential roles of FGFR signalling in the nucleus. These neglected areas are proving to be of great interest clinically and are intimately linked, at least in pancreatic cancer. The importance of the stroma in cancer is well accepted, both as a conduit/barrier for treatment and as a target in its own right. Nuclear receptors are less acknowledged as targets, largely due to historical scepticism as to their existence or importance. However, increasing evidence from across the receptor tyrosine kinase field is now strong enough to make the study of nuclear growth factor receptors a major area of interest.

Nuclear translocation of FGFR1 and FGF2 in pancreatic stellate cells facilitates pancreatic cancer cell invasion.

Pancreatic cancer is characterised by desmoplasia, driven by activated pancreatic stellate cells (PSCs). Over-expression of FGFs and their receptors is a feature of pancreatic cancer and correlates with poor prognosis, but whether their expression impacts on PSCs is unclear. At the invasive front of human pancreatic cancer, FGF2 and FGFR1 localise to the nucleus in activated PSCs but not cancer cells. In vitro, inhibiting FGFR1 and FGF2 in PSCs, using RNAi or chemical inhibition, resulted in significantly reduced cell proliferation, which was not seen in cancer cells. In physiomimetic organotypic co-cultures, FGFR inhibition prevented PSC as well as cancer cell invasion. FGFR inhibition resulted in cytoplasmic localisation of FGFR1 and FGF2, in contrast to vehicle-treated conditions where PSCs with nuclear FGFR1 and FGF2 led cancer cells to invade the underlying extra-cellular matrix. Strikingly, abrogation of nuclear FGFR1 and FGF2 in PSCs abolished cancer cell invasion. These findings suggest a novel therapeutic approach, where preventing nuclear FGF/FGFR mediated proliferation and invasion in PSCs leads to disruption of the tumour microenvironment, preventing pancreatic cancer cell invasion.

Fibroblast growth factor family as a potential target in the treatment of hepatocellular carcinoma.

Hepatocellular cancer (HCC) is currently the third leading cause of cancer death worldwide. The prognosis of patients diagnosed with late-stage disease is dismal due to high resistance to conventional systemic therapies. The introduction of sorafenib, despite its limited efficacy, as the standard systemic therapy for advanced HCC has paved a way for targeted molecular therapies for HCC. Fibroblast growth factor (FGF) signaling plays an important role in the developing embryo and the adult. The FGF signaling pathway is often hijacked by cancer cells, including HCC. Several alterations in FGF signaling correlate with poor outcome in HCC patients, suggesting that this family of signaling molecules plays an important role in the development of HCC. Multikinase inhibitors targeting FGF signaling are currently under investigation in clinical trials. This review discusses the current understanding of the biological and clinical implications of aberrant FGF signaling in the prognosis, diagnosis, and treatment of HCC.