Panel Interview of ONcology practices with Emergent Experience of teclistamab in the Real world: the TecPIONEER Study.

OBJECTIVE: To understand clinicians' current teclistamab step-up dosing (SUD) model and how they envision future administration models, as well as perceived barriers and facilitators to these models in day-to-day clinical practice. METHODS: Interviews of clinicians with RW experience administering teclistamab, with a subsequent roundtable discussion to discuss interview findings. Topics of interest included managing adverse events (AE), and handling logistics of SUD and transition of care (ToC). RESULTS: 20 clinicians representing 19 practices participated. Of 14 practices administering inpatient teclistamab SUD, 12 (86%) utilized a single admission. A day 1-3-5 dosing schedule with a 7-day length of stay was planned in 10/14 (71%). The remaining 5 practices employed outpatient or hybrid SUD. SUD models depended on cellular therapy experience, patient volume, and monitoring capabilities. Clinicians desired to administer SUD outpatient for convenience and reduced healthcare resource use. 11% of practices reported using tocilizumab for cytokine release syndrome (CRS) prophylaxis, whilst it was uniformly used to treat grade 2+ CRS. Corticosteroids were the preferred treatment for neurotoxicity. Infection prophylaxis with intravenous immunoglobulin was reported by 89% of practices. Patient- and institution-level factors affected decision-making of transitioning patients back to referring sites after SUD. CONCLUSION: The results consolidated practice-based experiences and indicated diverse RW SUD models and patient management strategies in practices with familiarity with teclistamab AE management and ToC protocols. Inpatient SUD is common, with expectations that approaches will evolve toward outpatient or community-based administration. Further research is needed to investigate outcomes of different care models and AE management strategies.

Multiple myeloma is a blood cancer that forms in plasma cells. Teclistamab is a new treatment for patients with multiple myeloma who have received prior treatment but for whom their multiple myeloma has come back or stopped responding to treatment multiple times. Because teclistamab works differently than other existing multiple myeloma treatments, there is a need to understand how oncologists who have experience with teclistamab are managing their patients in order to inform best practices for use by more healthcare providers. We interviewed oncologists that treat patients with multiple myeloma to understand their experiences with teclistamab, including how they manage initial dosing (step-up dosing) processes, treat adverse events, and transition patients to outpatient or external clinics for continued care. Most practices were administering step-up dosing of teclistamab in an inpatient setting soon after teclistamab became a treatment option, with a high level of desire to move the initial dosing to an outpatient setting in the near future. Those that were already administering step-up dosing in an outpatient setting had models unique to their practice. Oncologists described numerous processes for monitoring and managing adverse events of the treatment, including treating patients with preventative medications and regularly monitoring vital signs throughout step-up dosing. Oncologists expected that their teclistamab administration processes will likely evolve over time as they gain more familiarity with the treatment, and will need to consider patient-level factors to administer step-up dosing in an outpatient setting.

Comparative Effectiveness of Teclistamab Versus Real-World Physician's Choice of Therapy in LocoMMotion and MoMMent in Triple-Class Exposed Relapsed/Refractory Multiple Myeloma.

INTRODUCTION: Teclistamab is the first approved B cell maturation antigen × CD3 bispecific antibody with precision dosing for the treatment of triple-class exposed (TCE) relapsed/refractory multiple myeloma (RRMM). We compared the effectiveness of teclistamab in MajesTEC-1 versus real-world physician's choice of therapy (RWPC) in patients from the prospective, non-interventional LocoMMotion and MoMMent studies. METHODS: Patients treated with teclistamab from MajesTEC-1 (N = 165) were compared with an external control arm from LocoMMotion (N = 248) or LocoMMotion + MoMMent pooled (N = 302). Inverse probability of treatment weighting adjusted for imbalances in prognostic baseline characteristics. The relative effect of teclistamab versus RWPC for overall response rate (ORR), very good partial response or better (≥ VGPR) rate, and complete response or better (≥ CR) rate was estimated with an odds ratio using weighted logistic regression transformed into a response-rate ratio (RR) and 95% confidence interval (CI). Weighted proportional hazards regression was used to estimate hazard ratios (HRs) and 95% CIs for duration of response (DOR), progression-free survival (PFS), and overall survival (OS). RESULTS: Baseline characteristics were well balanced between treatment cohorts after reweighting. Patients treated with teclistamab had significantly improved outcomes versus RWPC in LocoMMotion: ORR (RR [95% CI], 2.44 [1.79-3.33]; p < 0.0001), ≥ VGPR (RR 5.78 [3.74-8.93]; p < 0.0001), ≥ CR (RR 113.73 [15.68-825.13]; p < 0.0001), DOR (HR 0.39 [0.24-0.64]; p = 0.0002), PFS (HR 0.48 [0.35-0.64]; p < 0.0001), and OS (HR 0.64 [0.46-0.88]; p = 0.0055). Teclistamab versus RWPC in LocoMMotion + MoMMent also had significantly improved outcomes: ORR (RR 2.41 [1.80-3.23]; p < 0.0001), ≥ VGPR (RR 5.91 [3.93-8.88]; p < 0.0001), ≥ CR (RR 132.32 [19.06-918.47]; p < 0.0001), DOR (HR 0.43 [0.26-0.71]; p = 0.0011), PFS (HR 0.49 [0.37-0.66]; p < 0.0001), and OS (HR 0.69 [0.50-0.95]; p = 0.0247). CONCLUSION: Teclistamab demonstrated significantly improved effectiveness over RWPC in LocoMMotion ± MoMMent, emphasizing its clinical benefit as a highly effective treatment for patients with TCE RRMM. TRIAL REGISTRATION: MajesTEC-1, ClinicalTrials.gov NCT03145181 (phase 1) and NCT04557098 (phase 2); LocoMMotion, ClinicalTrials.gov NCT04035226; MoMMent, ClinicalTrials.gov NCT05160584.

Teclistamab versus real-world physician's choice of therapy in triple-class exposed relapsed/refractory multiple myeloma.

Aim: We compared the effectiveness of teclistamab versus real-world physician's choice of therapy (RWPC) in triple-class exposed relapsed/refractory multiple myeloma. Materials & methods: MajesTEC-1 eligibility criteria were applied to the RWPC cohort. Baseline covariate imbalances were adjusted using inverse probability of treatment weighting. Overall survival, progression-free survival and time to next treatment were compared. Results: After inverse probability of treatment weighting, baseline characteristics were similar between cohorts (teclistamab, n = 165; RWPC, n = 364 [766 observations]). Teclistamab treated patients had numerically better overall survival (hazard ratio [HR]: 0.82 [95% CI: 0.59-1.14]; p = 0.233) and significantly greater progression-free survival (HR: 0.43 [0.33-0.56]; p < 0.0001) and time to next treatment (HR: 0.36 [0.27-0.49]; p < 0.0001) versus the RWPC cohort. Conclusion: Teclistamab offered clinical benefit over RWPC in triple-class exposed relapsed/refractory multiple myeloma.

Comparative Efficacy of Teclistamab Versus Physician's Choice of Therapy in the Long-term Follow-up of APOLLO, POLLUX, CASTOR, and EQUULEUS Clinical Trials in Patients With Triple-class Exposed Relapsed or Refractory Multiple Myeloma.

BACKGROUND: The efficacy and safety of teclistamab in patients with RRMM who received ≥3 prior lines of therapy and were triple-class exposed (TCE) are being evaluated in the single-arm, multicohort, phase I/II MajesTEC-1 trial (NCT04557098). We evaluated the comparative effectiveness of teclistamab versus physician's choice (PC) of therapy in TCE RRMM patients. METHODS: Individual patient-level data from MajesTEC-1 patients who received teclistamab (1.5 mg/kg weekly; clinical cutoff March 16, 2022) were included. An external control arm was created from patients in long-term follow-up of 4 clinical trials of daratumumab who were treated with PC therapy after discontinuation of trial treatments. In the primary analysis, inverse probability of treatment weighting was used to adjust for imbalances in 9 baseline covariates. A fully adjusted model included 5 additional prognostic factors. Outcomes included overall response rate (ORR), very good partial response or better (≥VGPR) rate, overall survival (OS), progression-free survival (PFS), and time to next treatment (TTNT). RESULTS: After adjustment, baseline characteristics were balanced between cohorts. In the primary analysis, outcomes were significantly improved with teclistamab versus PC: ORR (OR [95% CI] 4.81 [3.04-7.72]; P < .0001); ≥VGPR rate (OR, 12.07 [6.91-22.11]; P < .0001); OS (HR, 0.54 [0.40-0.73]; P < .0001); PFS (HR, 0.59 [0.46-0.78]; P = .0001); and TTNT (HR, 0.32 [0.24-0.42]; P < .0001). Results of the fully adjusted model were consistent with the primary analysis. CONCLUSION: Teclistamab showed significantly improved effectiveness versus PC on all outcomes, highlighting its clinical benefit in patients with TCE RRMM and limited treatment options.

Caregiver survey in glioblastoma focused on cognitive dysfunction: development and results from a multicenter study.

Aim: To develop a cognitive dysfunction (CD) focused questionnaire to evaluate caregiver burden in glioblastoma. Materials & methods: The survey was developed from stakeholder consultations and a pilot study, and disseminated at eight US academic cancer centers. Caregivers self-reported caring for an adult with glioblastoma and CD. Results: The 89-item survey covered demographics, CD symptoms and caregiver burden domains. Among 185 caregivers, most were white, educated females and reported memory problems as the most common CD symptom. An exposure-effect was observed, with increase in number of CD symptoms significantly associated with greater caregiver burden. Conclusion: This questionnaire could guide caregiver interventions and be adapted for use longitudinally, in community cancer settings, and in patients with brain metastases.

Glioblastoma (GBM) is a very aggressive brain cancer. People who have GBM have trouble remembering things and are unable to do things they used to do. These changes can be very hard. Researchers are trying to better understand what it is like for people who take care of people with GBM (or caregivers). In this study, researchers created a new survey for caregivers. The survey included questions about what caregivers see happening in their loved one with GBM. Caregivers said that memory problems were common. Also, when the patient had more problems the caregiver had a harder time, too. Researchers hope to improve the survey and use it in the future for more studies.

Caregiver burden by treatment and clinical characteristics of patients with glioblastoma.

BACKGROUND: Glioblastoma is an incurable disease with a poor prognosis. For caregivers of people with glioblastoma, the burden of care can be high. Patients often present with different clinical characteristics, which may impact caregiver burden in different ways. This study aimed to evaluate associations between patient clinical characteristics and caregiver burden/quality of life (QoL). METHODS: Caregiver-patient dyads were enrolled at 7 academic cancer centers in the United States. Eligible caregiver participants were self-reported as the primary caregiver of an adult living with glioblastoma and completed a caregiver burden survey. Eligible patients were age ≥ 18 years at glioblastoma diagnosis and alive when their respective caregiver entered the study, with the presence of cognitive dysfunction confirmed by the caregiver. Data were analyzed with descriptive statistics and multivariable analyses. RESULTS: The final cohort included 167 dyads. Poor patient performance status resulted in patient difficulty with mental tasks, more caregiving tasks, and increased caregiving time. Language problems were reported in patients with left-sided lesions. Patient confusion was negatively associated with all caregiver domains: emotional health, social health, general health, ability to work, confidence in finances, and overall QoL. Better caregiver QoL was observed in patients with frontal lobe lesions versus non-frontal lobe lesions. CONCLUSION: This study reinforced that patient performance status is a critical clinical factor that significantly affects caregiver burden, caregiving tasks, and caregiver time. Additionally, patient confusion affects multiple facets of caregiver burden/QoL. These results could be used to support guided intervention for caregiver support, customized to the patient experience.

Network meta-analysis of nivolumab plus ipilimumab in the second-line setting for advanced hepatocellular carcinoma.

Aims: To compare the efficacy of nivolumab 1 mg/kg + ipilimumab 3 mg/kg with regorafenib 160 mg, cabozantinib 60 mg and nivolumab 3 mg/kg monotherapy for second-line treatment of advanced hepatocellular carcinoma. Materials & methods: Indirect comparison using network meta-analysis and propensity score weighting. Results: Nivolumab 1 mg/kg + ipilimumab 3 mg/kg had significantly higher objective response rate (median 31.2% [95% credible interval: 19.6-44.5%]) than cabozantinib (4.2% [2.0-6.5%]) and regorafenib (4.8% [1.1-8.3%]), and significantly longer overall survival (cabozantinib: hazard ratio: 0.46 [95% credible interval: 0.27-0.79]; regorafenib: 0.56 [0.32-0.97]). Nivolumab 1 mg/kg + ipilimumab 3 mg/kg had significantly better objective response rate (difference 21.0% [4.5-37.5%]) and overall survival (hazard ratio: 0.58 [0.35-0.96]) than nivolumab monotherapy. Conclusion: Nivolumab 1 mg/kg + ipilimumab 3 mg/kg had a superior efficacy versus cabozantinib 60 mg, regorafenib 160 mg and nivolumab 3 mg/kg monotherapy as second-line therapy for advanced hepatocellular carcinoma.

Methane emissions from abandoned coal and oil and gas developments in New Brunswick and Nova Scotia.

Energy reserves have been exploited in the Atlantic Canadian provinces since the early 1600s, and many fossil fuel extraction sites have been abandoned over this long history of energy development. Oil, natural gas, and coal extraction sites are a source of greenhouse gas emissions, particularly for methane (CH4). In this study, we used multiple sampling methods to measure CH4 from abandoned coal mine openings in Nova Scotia and a legacy oilfield in New Brunswick. Atmospheric and shallow soil gases were sampled around legacy sites using flux rate chamber measurements (spatial and temporal) and plot-scale atmospheric gas surveys, in addition to regional gas screening surveys over larger populations of sites to confirm whether small-scale observations were reflected regionally. Only one oil and gas site (2.4 ± 3.1⋅ 102 mg m- 2 day- 1) and one abandoned coal mine opening (1.0 ± 1.1⋅ 102 mg m- 2 day- 1) were affected by soil CH4 migration, though rates of leakage were minimal and would rank as low severity on industrial scales. Plot-scale atmospheric gas screening showed super-ambient CH4 concentrations at 5 sites in total (n = 16), 2 coal adits and 3 abandoned oil and gas wells. Regional gas screening surveys suggest that 11% of legacy oil and gas sites have some emission impacts, compared with 1-2% of legacy coal sites. These frequencies are close, albeit lower than the 15% of legacy oil and gas sites and 10% of abandoned coal mine openings flagged from our aggregated small-scale observations. These sites may emit less than other developments studied to date either because more time has elapsed since extraction, or because differences in regional geology reduce the likelihood of sustained emissions. This study provides valuable information to help understand the methane emission risks associated with legacy energy sites.

Treatment patterns and economic outcomes in patients with juvenile idiopathic arthritis.

Purpose: To describe health care resource utilization (HCRU) and costs among patients with juvenile idiopathic arthritis (JIA) compared to patients without JIA and to describe treatment patterns among JIA patients who initiated biologic and non-biologic disease-modifying antirheumatic drugs (DMARDs). Patients and methods: The IBM MarketScan® Commercial Database was used to identify patients aged 2-17 years with a new JIA diagnosis (index date) and 12 months continuous enrollment pre- and post-diagnosis from 2008 to 2016. JIA patients were matched to non-JIA patients on age, gender, region, and health plan type. Patients with other rheumatic or autoimmune conditions were excluded. Receipt of a biologic and/or non-biologic was evaluated on or after the new JIA diagnosis. Results: A total of 3,815 JIA patients were matched to 11,535 non-JIA patients (mean age 10.0 [SD=4.5], 69% female). Average total costs were greater for JIA patients than non-JIA controls ($18,611 [SD=$42,104; median=$8,189] versus $2,203 [SD=$9,309; median=$649], p<0.001). Outpatient pharmacy costs were 33.6% of the total costs among JIA patients compared to 18.4% among non-JIA patients (p<0.001). The proportion of inpatient cost (11.4% versus 14.3%, p<0.001) and outpatient costs (55% versus 67.4%, p<0.001) of total costs was lower among JIA patients compared to non-JIA patients. Patients with 12 months of continuous enrollment post-treatment initiation (n=2,014) were classified as non-biologic only (n=734), biologic only (n=873), and both biologic and non-biologic (n=407) users. Among biologic and non-biologic users, 41.1% and 56.8% were persistent on their index medication for 12 months. Of patients treated with a biologic only, TNF inhibitors (TNFi) comprised 87.1% of the total treatment costs. Conclusion: JIA is associated with increased costs and utilization in every HCRU category compared to matched non-JIA patients. While JIA-related costs varied by treatment cohort, patients on biologic DMARDs had substantially higher costs than patients on non-biologic DMARDs and fewer than one-half were persistent at 12 months after biologic initiation.

Cost per response for abatacept versus adalimumab in patients with seropositive, erosive early rheumatoid arthritis in the US, Germany, Spain, and Canada.

BACKGROUND: Effective treatment of rheumatoid arthritis (RA) with biologic DMARDs poses a significant economic burden. The AMPLE (Abatacept versus adaliMumab comParison in bioLogic-naïvE RA subjects with background methotrexate) trial was a head-to-head, randomized study comparing abatacept with adalimumab. A post hoc analysis showed improved efficacy for abatacept in patients with versus without seropositive, erosive early RA. OBJECTIVE: The aim of the current study was to evaluate the cost per response (ACR20/50/70/90 and HAQ-DI) and patient in remission (DAS28-CRP, CDAI, and SDAI) for abatacept relative to adalimumab, in patients with seropositive, erosive early RA in the US, Germany, Spain, and Canada. METHODS: A previously published model was used to compare abatacept and adalimumab in a cohort of 1000 patients over 2 years. Clinical inputs were updated based on two subpopulations from the AMPLE trial. Cohort 1 included patients with early RA (disease duration ≤ 6 months), RF and/or ACPA seropositivity, and > 1 radiographic erosion. Cohort 2 included patients with RA in whom at least one of these criteria was absent. RESULTS: For cohort 1, all incremental costs per additional health gain (patient response or patient in remission) favoured abatacept in all countries, except for DAS28-CRP remission in Canada. Cost savings versus adalimumab were greater when more stringent response criteria were applied and also in cohort 1 patient (versus cohort 2 patients). CONCLUSION: The cost per responder and patient in remission favoured abatacept in patients with seropositive, erosive early RA across all the countries. In this patient population, the use of abatacept instead of adalimumab can lead to lower costs in the US, Germany, Spain, and Canada.

The economic burden of switching targeted disease-modifying anti-rheumatic drugs among rheumatoid arthritis patients.

AIMS: To estimate real world healthcare costs and resource utilization of rheumatoid arthritis (RA) patients associated with targeted disease modifying anti-rheumatic drugs (tDMARD) switching in general and switching to abatacept specifically. MATERIALS AND METHODS: RA patients initiating a tDMARD were identified in IMS PharMetrics Plus health insurance claims data (2010-2016), and outcomes measured included monthly healthcare costs per patient (all-cause, RA-related) and resource utilization (inpatient stays, outpatient visits, emergency department [ED] visits). Generalized linear models were used to assess (i) average monthly costs per patient associated with tDMARD switching, and (ii) among switchers only, costs of switching to abatacept vs tumor necrosis factor inhibitors (TNFi) or other non-TNFi. Negative binomial regressions were used to determine incident rate ratios of resource utilization associated with switching to abatacept. RESULTS: Among 11,856 RA patients who initiated a tDMARD, 2,708 switched tDMARDs once and 814 switched twice (to a third tDMARD). Adjusted average monthly costs were higher among patients who switched to a second tDMARD vs non-switchers (all-cause: $4,785 vs $3,491, p < .001; RA-related: $3,364 vs $2,297, p < .001). Monthly RA-related costs were higher for patients switching to a third tDMARD compared to non-switchers remaining on their second tDMARD ($3,835 vs $3,383, p < .001). Switchers to abatacept had significantly lower RA-related monthly costs vs switchers to TNFi ($3,129 vs $3,436, p = .021), and numerically lower all-cause costs ($4,444 vs $4,741, p = 0.188). Switchers to TNFi relative to abatacept had more frequent inpatient stays after switch (incidence rate ratio (IRR) = 1.85, p = .031), and numerically higher ED visits (IRR = 1.32, p = .093). Outpatient visits were less frequent for TNFi switchers (IRR = 0.83, p < .001) compared to switchers to abatacept. LIMITATIONS AND CONCLUSIONS: Switching to another tDMARD was associated with higher healthcare costs. Switching to abatacept, however, was associated with lower RA-related costs, fewer inpatient stays, but more frequent outpatient visits compared to switching to a TNFi.

Hospital Resource Utilization and Costs Associated With Warfarin Versus Apixaban Treatment Among Patients Hospitalized for Venous Thromboembolism in the United States.

A real-world US database analysis was conducted to evaluate the hospital resource utilization and costs of patients hospitalized for venous thromboembolism (VTE) treated with warfarin versus apixaban. Additionally, 1-month readmissions were evaluated. Of 28 612 patients with VTE identified from the Premier Hospital database (August 2014-May 2016), 91% (N = 26 088) received warfarin and 9% (N = 2524) received apixaban. Outcomes were assessed after controlling for key patient/hospital characteristics. For index hospitalizations, the average length of stay (LOS) was longer (3.8 vs 3.1 days, P < .001; difference: 0.7 days) and mean hospitalization cost higher (US$3224 vs US$2,740, P < .001; difference: US$484) for warfarin versus apixaban-treated patients. During the 1-month follow-up period, warfarin treatment was associated with a greater risk of all-cause readmission (odds ratio [OR]: 1.27; 95% confidence interval [CI]: 1.09-1.48, P = .003), major bleeding (MB)-related readmission (OR: 2.10; 95% CI: 1.03-4.27, P = .04), and any bleeding-related readmission (OR: 1.67; 95% CI: 1.09-2.56, P = .02) versus apixaban. The results of this real-world analysis show that compared to warfarin, apixaban treatment was associated with shorter index hospital stays, lower index hospitalization costs, and reduced risk of MB-related readmissions among hospitalized patients with VTE.

Biliary stenting versus surgical bypass for palliation of periampullary malignancy.

BACKGROUND: Patients with periampullary cancers may not be suitable for curative resection due to locally advanced disease, metastases, or poor health. Biliary stenting and surgical bypass are utilized for symptom control, but the true benefit of one technique over the other is not clear. METHODS: A retrospective analysis of case records was undertaken of patients with periampullary (pancreatic head/uncinate process, distal bile duct, and ampulla of Vater and surrounding duodenum) malignancy treated between June 2004 and June 2010 in a tertiary center by palliative biliary stenting or palliative surgical bypass. RESULTS: Of the 69 patients included in the analysis, combined biliary and gastric bypass was performed on 28, while 41 underwent biliary stent (metallic, n = 39) insertion. Patients undergoing stenting were significantly older and less likely to be offered chemotherapy than those from the surgical bypass group. Overall, there were significantly more complications in the stent insertion group (85 %) than the surgical bypass group (36 %) (p = 0.003). The stent group required significantly more subsequent procedures than the surgical bypass group. Metal stent obstruction occurred in 16 of 39 (41 %) patients, with a median stent patency of 224 days. The overall median survival of patients in this study was 7 months with no significant difference between the groups (p = 0.992). The presence of metastases at presentation was the only independent factor associated with decreased survival. CONCLUSION: There was no survival difference between stenting vs. surgical bypass for palliation of periampullary cancer. There was, however, a high rate of stent occlusion and need for repeat procedures in patients treated by metal stenting, suggesting that stenting may be best suited to patients predicted as having the shortest survival.

Selective holographic detection of glucose using tertiary amines.

Introducing tertiary amine monomers into holographic sensors containing phenylboronic acids gives greatly improved selectivity for glucose.

Crosslinking of phenylboronic acid receptors as a means of glucose selective holographic detection.

A holographic sensor for the detection of glucose has been developed that is based on a hydrogel film containing phenylboronic acid receptors. Changes to the replay wavelength of the hologram were used to characterise the swelling and de-swelling behaviour of the hydrogel matrix upon receptor-ligand binding. The effect of introducing a fixed positive charge into the polymer matrix by modification of the hydrogel with a quaternary amine group (3-acrylamidopropyl)trimethylammonium chloride (ATMA), was investigated for a range of sugars and the alpha-hydroxy acid, lactate, at physiological pH. The quaternary amine-modified hydrogel matrix was found to contract in the presence of glucose, whereas, it was minimally responsive to other saccharides. The selectivity of the sensor for glucose compared to lactate was also significantly improved compared to the unmodified film. A crosslinking mechanism is proposed to explain the enhanced selectivity to glucose.

Holographic glucose sensors.

A novel holographic sensor system capable of detecting dynamic changes in glucose concentration has been developed. The hologram is recorded within a bio-compatible hydrogel matrix containing phenylboronic acid derivatives. On binding glucose, the colour of the hologram red-shifts to longer wavelengths as the hydrogel expands and this colour change is used to quantify glucose concentration. However, phenylboronic acids are non-selective and bind a wide variety of cis-diols. In blood, glucose is the only sugar found free at high concentration, whilst other sugars are typically found as part of glycoproteins and macromolecular structures. Although glycoproteins have been shown to have no effect on the sensor, phenylboronic acids can bind lactate much more readily than glucose. We have designed two polymer hydrogel systems to increase the selectivity of the sensor for glucose over lactate. The first involved the use of high concentrations of 3-acrylamidophenylboronic acid (3-APB) whilst the second system utilised 2-acrylamido-5-fluorophenylboronic acid (5-F-2-MAPB). Both systems displayed an increased selectivity to glucose over lactate at physiological pH and ionic strength and could be deployed as selective holographic sensors for glucose detection in physiological fluids.

Metabolite-sensitive holographic biosensors.

A new type of biosensor that combines the inexpensiveness and mass-produceability of reflection holograms with the selectivity and specificity of enzymes is described. pH-sensitive holographic sensors were fabricated from ionizable monomers incorporated into thin, polymeric, hydrogel films which were transformed into volume holograms using a diffusion method coupled with holographic recording, using a frequency-doubled Nd:YAG laser (532 nm). These holograms were used as transducer systems to monitor the pH changes associated with specific enzymatic reactions to construct prototype urea- and penicillin-sensitive biosensors. The diffraction wavelength (color) of the holographic biosensors was used to characterize their shrinkage and swelling behavior as a function of analyte concentration. The potential of these sensors for the measurement of the clinically and industrially important metabolites urea and penicillin G is demonstrated.

pH-sensitive holographic sensors.

Holographic sensors for monitoring H+ (pH) have been fabricated from ionizable monomers incorporated into thin, polymeric, hydrogel films which were transformed into volume holograms using a diffusion method coupled with holographic recording, using a frequency doubled Nd:YAG laser (532 nm). Unlike other optical pH sensors, it is possible to tailor the operational replay wavelength of the holographic sensor by careful control of the exposure conditions. The holographic diffraction wavelength (color) of the holograms was used to characterize their shrinkage and swelling behavior as a function of pH in various media. The effects of hydrogel composition, ionic strength, temperature, and factors influencing reversibility and response time are evaluated. Optimized holographic pH sensors show milli-pH resolution. The pH-sensing range of the holograms can be controlled through variation of the nature of the ionizable co-monomer used in polymer film construction; a series of holographic sensors displaying visually perceptible, fully reversible color changes over different pH ranges are demonstrated. A poly(hydroxyethyl methacrylate-co-methacrylic acid) holographic sensor was shown to be able to quantify the change in H+ concentrations in real time in a sample of milk undergoing homolactic fermentation in the presence of Lactobacillus casei.