Clustering of Tadalafil API Samples According to their Manufacturer in the Context of API Falsification Detection.

This paper reports the results of the active pharmaceutical ingredient (API) fingerprint study, organised by the General European Official Medicines Control Laboratory Network (GEON), on tadalafil. A classical market surveillance study, evaluating compliance to the European Pharmacopoeia, was combined with a fingerprint study, the latter to obtain characteristic data for the different manufacturers, allowing the network laboratories to conduct authenticity tests for future samples, as well as to detect substandard and falsified samples. In total, 46 tadalafil API samples from 13 different manufacturers were collected. For all samples fingerprint data was collected through analysis of impurities and residual solvents, mass spectrometric screening, X-ray powder diffraction and proton nuclear magnetic resonance (1H-NMR). Chemometric analysis revealed that all manufacturers could be characterised based on the impurity, residual solvent and 1H-NMR data. Future suspicious samples in the network will therefore be analysed with these techniques in order to attribute the sample to one of the manufacturers. If the sample cannot be attributed, a more profound investigation will be necessary to reveal the origin of the sample. In cases where the suspect sample is claimed to be from one of the manufacturers included in this study, analysis can be limited to the test distinguishing that manufacturer.

The purity of tattoo inks, screening substances of high concern.

BACKGROUND: Tattoos have grown in popularity in recent years with over 60 million Europeans having a tattoo nowadays. Currently, there is no harmonized legislation in Europe but from 2022 on, tattoo inks will be regulated through a REACH Amendment implementing compound-specific restrictions. METHODOLOGY: A screening method based on LC-QqQ-MS was developed and validated for screening 40 substances of high concern in tattoo inks. An additional quantification method was validated to quantify 5-nitro toluidine and 4-chloroaniline in tattoo inks with high accuracy. The method was validated according to the total error approach with an acceptance value of ±20% RESULTS: The methodology was applied to 86 samples of which 26 are violating the current Resolution ResAP (2008). 5-nitro toluidine was found in 16 samples, all of them having an unacceptable health risk, with an average concentration of 29 µg/g basic violet 10, basic red 1, 4-chloroaniline, and basic red 9 were detected 8, 7, 4, and 3, times respectively. Counterfeit products with lower quality were observed. CONCLUSION: Our results show that low-quality tattoo inks are easily available to the European consumer. In line with literature, most infringements were observed with red/brown inks which is not surprising since these colors are most often associated with adverse health effects.

GEONs API fingerprint project: Selection of analytical techniques for clustering of sildenafil citrate API samples.

Through its Active Pharmaceutical Ingredient Working Group (API-WG) the General European Official Medicines Control Laboratory (OMCL) Network (GEON), co-ordinated by the European Directorate for the Quality of Medicines & HealthCare (EDQM), regularly organises market surveillance studies for specific APIs for conformity to their monograph in the European Pharmacopoeia. During the past years some studies were combined with a fingerprint study of the APIs. The idea is to obtain a fingerprint for each manufacturer of the API under investigation, allowing the OMCL network to identify future samples as well as to detect substandard and falsified APIs. This paper reports the results of the latest fingerprint study, organised on sildenafil citrate API samples. Seventy-nine samples from 14 different manufacturers were collected throughout the Network. Fingerprint data was collected through Mid-Infrared spectroscopy, Raman spectroscopy, liquid chromatography for related substances, gas chromatography for residual solvents, X-ray diffraction and Nuclear Magnetic Resonance (NMR) spectroscopy. Chemometrics applied to the collected data showed that all manufacturers could be discriminated based on the data of only three of these tests, i.e. gas chromatography for residual solvents, X-ray diffraction and proton NMR. Suspicious API samples for sildenafil citrate will therefore be analysed in the future with the selected techniques in order to link the sample to a manufacturer or demonstrate the absence of such link. If the sample cannot be attributed to one of the manufacturers, further analysis and research on provenance and identity will be required. Of course, if the suspected sample claims to originate from one of the manufacturers included in the study, analysis can be limited to the test distinguishing this manufacturer.

European fingerprint study on omeprazole drug substances using a multi analytical approach and chemometrics as a tool for the discrimination of manufacturing sources.

Like drug products, Active Pharmaceutical Ingredients (APIs) are subject to substandard and falsification issues, which represent a threat to patient health. In order to monitor the quality of drug substances and prevent the use of non-compliant APIs, Official Medicine Control Laboratories work together in a European network developing coordinated strategies and programmes. The API working group proposed a market surveillance study on omeprazole and omeprazole magnesium with the objectives of controlling the pharmaceutical quality of samples, checking compliance with the monographs of the European Pharmacopoeia, and collecting analytical fingerprints that could be further used to differentiate manufacturing sources for future authenticity investigations. The study described in this article reports the analysis carried out by 7 European laboratories on 28 samples from 11 manufacturers with 5 analytical techniques (related substances with HPLC, residual solvents with GC-MS, near infrared spectroscopy, proton nuclear magnetic resonance spectroscopy and X-ray powder diffractometry). The large amount of resulting analytical data were centralized and treated with two chemometric methods: Principal Component Analysis and Hierarchical Clustering Analysis. Data were analyzed separately and in combination (data fusion), allowing us to conclude that NMR and XRPD were suitable to differentiate samples originating from 9 out of 11 manufacturers. Analytical fingerprints associated with chemometrics were demonstrated to be a valuable methodology to discriminate manufacturers of omeprazole and omeprazole magnesium APIs and detect future substandard and falsified APIs.

Combining attenuated total reflectance- infrared spectroscopy and chemometrics for the identification and the dosage estimation of MDMA tablets.

The principal objective of the Belgian Early Warning System on drugs (BEWSD) of the Reitox national focal point is to collect and disseminate information on the appearance of drugs circulating on the local drug market. To this end, one of the actions of BEWSD is to annually collect substances that are circulating on the Belgian summer festivals. Every year a high number of seized samples is collected and submitted to qualitative and quantitative analysis. The goal is twofold: next to the monitoring of the drug market, a surveillance on the quality of drugs is established with main focus on the evolution of MDMA dosages in ecstasy as well as the emergence of new psychoactive substances (NPS). The presented paper focusses on the characterization of ecstasy tablets, seized at summer festivals in the seasons 2016 and 2017. Samples were classically analysed with GC-MS and UV spectroscopy, representing a certain cost and time for analysis. In this paper, an approach is presented based on infrared spectroscopy to first differentiate ecstasy from other party drugs and further quantify MDMA in the tablets. To this end, a comparison was done between NIR and Mid-IR spectroscopy in combination with partial least squares-discriminant analysis (PLS-DA) and -regression (PLS). For the differentiation between MDMA positive and negative tablets, the best results were obtained by NIR and PLS-DA and resulted in a correct classification rate of 96% for an external test set. In addition, for the quantification of MDMA, the best results were also obtained with a PLS model based on NIR spectra. A RMSEP for the external test set of 3.86 was obtained and an R2 value between real and predicted values of 0.88. This means that for the dosage MDMA per tablet, when taking into account the range of masses of the tablets in our sample set, the error varies between 8 mg for low mass tablets and 27.8 mg for high mass tablets. These are acceptable values for a first estimation and give a first indication of the risk the tablet may represent. The presented approach will be of use for on-site analysis. Moreover, when applied in a laboratory environment, it will reduce the workload for the analysis of MDMA tablets and thus liberating resources.

A strategy based on fingerprinting and chemometrics for the detection of regulated plants in plant food supplements from the Belgian market: Two case studies.

The sale and consumption of plant food supplements is increasing, especially in the western world. A lot of these supplements can be bought through internet, where a lot of illegal trade is going on. Every year seized dietary supplements are send to laboratories in order to screen for the presence of chemical adulterants or illegally added active pharmaceutical ingredients, though also herbal adulteration occurs and is given less attention. In this paper a two-step approach is presented based on fingerprints recorded by both infrared spectroscopy as liquid chromatography with UV-detection for the screening of five regulated plants used in respectively dietary supplements for slimming and potency enhancement. Both types of fingerprints are combined with chemometric techniques in order to obtain classification models. A first classification model is calculated based on the infrared data and gives a first idea about the plant suspected to be present. This suspicion is then confirmed based on binary classification models calculated with the chromatographic data obtained for the suspected plant. In general, good classification models were obtained for each of the targeted plants. The approach was applied in a small market study comprising 35 dietary supplements for slimming and 34 for male potency enhancement. In total 21 samples were found to contain one of the five targeted plants.

EBMT prospective observational study on allogeneic hematopoietic stem cell transplantation in T-prolymphocytic leukemia (T-PLL).

Preliminary data suggest that allogeneic stem cell transplantation (allo-SCT) may be effective in T-prolymphocytic leukemia (T-PLL). The purpose of the present observational study was to assess the outcome of allo-SCT in patients aged 65 years or younger with a centrally confirmed diagnosis of T-PLL. Patients were consecutively registered with the EBMT at the time of transplantation and followed by routine EBMT monitoring but with an extended dataset. Between 2007 and 2012, 37 evaluable patients (median age 56 years) were accrued. Pre-treatment contained alemtuzumab in 95% of patients. Sixty-two percent were in complete remission (CR) at the time of allo-SCT. Conditioning contained total body irradiation with 6 Gy or more (TBI6) in 30% of patients. With a median follow-up of 50 months, the 4-year non-relapse mortality, relapse incidence, progression-free (PFS) and overall survival were 32, 38, 30 and 42%, respectively. By univariate analysis, TBI6 in the conditioning was the only significant predictor for a low relapse risk, and an interval between diagnosis and allo-SCT of more than 12 months was associated with a lower NRM. This study confirms for the first time prospectively that allo-SCT can provide long-term disease control in a sizable albeit limited proportion of patients with T-PLL.

Consumer protection provided by the European medical device and cosmetic legislation for condoms and lubricants.

Personal lubricants and lubricants used in condoms contain a number of ingredients which are also present in cosmetic products. These have to comply to the medical device regulation (745/2017) which should provide the same level of consumer protection, if not more, as foreseen in the legal framework of cosmetics (1223/2009). In the current study we developed an analytical method capable of identifying and quantifying 15 ingredients, commonly found in lubricants and cosmetics. Based upon their most important toxicological endpoint, the substances involved were grouped in three toxicological classes provoking either irritation, contact allergic dermatitis or systemic toxicity. The method was applied on 30 condoms and 54 personal lubricants present on the EU market. Their safety was assessed using the same reasoning as commonly applied for cosmetic ingredients. Higher mucosae susceptibility, the main exposed area for lubricants, was taken into account in this assessment. The results show that the majority of the products studied are safe. Nevertheless, for some products the safety could not be confirmed. The results also highlight the fact that there is no consensus for a number of ingredients, used as well in cosmetics as in medical devices. Alignment between both legislations would improve the safety of these products and further raise the general level of consumer protection.

Detection and identification of multiple adulterants in plant food supplements using attenuated total reflectance-Infrared spectroscopy.

Due to the rising popularity of dietary supplements, especially plant food supplements, and alternative herbal medicines, a whole market developed and these products became freely available through internet. Though several searches revealed that at least a part of these products, especially the ones obtained from websites disclosing their physical identity, are aldulterated with pharmaceutical compounds. This causes a threat for public health, since these compounds are not declared and therefore adverse effects will not immediately be related to the product. The more the adulterants can interfere with other medicinal treatments. Since the present active pharmaceutical ingredients are not declared on the package and the products are sold as 100% natural or herbal in nature, it is very difficult for custom personnel to discriminate between products to be confiscated or not. Therefore easy to apply analytical approaches to discriminate between adulterated and non-adulterated products are necessary. This paper presents an approach based on infrared spectroscopy combined with attenuated total reflectance (ATR) and partial least squares- discriminant analysis (PLS-DA) to easily differentiate between adulterated and non- adulterated plant food supplements and to get a first idea of the nature of the adulterant present. The performance of PLS-DA models based on Mid-IR and NIR data were compared as well as models based on the combined data. Further three preprocessing strategies were compared. The best performance was obtained for a PLS-DA model using Mid-IR data with the second derivative as preprocessing method. This model showed a correct classification rate of 98.3% for an external test set. Also eight real samples were screened using the model and for seven of these samples a correct classification was obtained. Generally it could be concluded that the obtained model and the presented approach could be used at customs to discriminate between adulterated and non-adulterated herbal food supplements and even get a first idea of the nature of the adulterant present. The more the presented approach hardly needs sample preparation.

Distinct factors determine the kinetics of disease relapse in adults transplanted for acute myeloid leukaemia.

BACKGROUND: Disease recurrence remains the major cause of death in adults with acute myeloid leukaemia (AML) treated using either intensive chemotherapy (IC) or allogenic stem cell transplantation (allo-SCT). AIMS: The timely delivery of maintenance drug or cellular therapies represent emerging strategies with the potential to reduce relapse after both treatment modalities, but whilst the determinants of overall relapse risk have been extensively characterized the factors determining the timing of disease recurrence have not been characterized. MATERIALS AND METHODS: We have therefore examined, using a series of sequential landmark analyses, relapse kinetics in a cohort of 2028 patients who received an allo-SCT for AML in CR1 and separately 570 patients treated with IC alone. RESULTS: In the first 3 months after allo-SCT, the factors associated with an increased risk of relapse included the presence of the FLT3-ITD (P < 0.001), patient age (P = 0.012), time interval from CR1 to transplant (P < 0.001) and donor type (P = 0.03). Relapse from 3 to 6 months was associated with a higher white cell count at diagnosis (P = 0.001), adverse-risk cytogenetics (P < 0.001), presence of FLT3-ITD mutation (P < 0.001) and time interval to achieve first complete remission (P = 0.013). Later relapse was associated with adverse cytogenetics, mutated NPM1, absence of chronic graft-versus-host disease (GVHD) and the use of in vivo T-cell depletion. In patients treated with IC alone, the factors associated with relapse in the first 3 months were adverse-risk cytogenetics (P < 0.001) and FLT3-ITD status (P = 0.001). The factors predicting later relapse were the time interval from diagnosis to CR1 (P = 0.22) and time interval from CR1 to IC (P = 0.012). DISCUSSION AND CONCLUSION: Taken together, these data provide novel insights into the biology of disease recurrence after both allo-SCT and IC and have the potential to inform the design of novel maintenance strategies in both clinical settings.

Reduced-intensity versus reduced-toxicity myeloablative fludarabine/busulfan-based conditioning regimens for allografted non-Hodgkin lymphoma adult patients: a retrospective study on behalf of the Société Francophone de Greffe de Moelle et de Thérapie Cellulaire.

BACKGROUND: Fludarabine/busulfan-based conditioning regimens are widely used to perform allogeneic stem-cell transplantation (allo-SCT) in high-risk non-Hodgkin lymphoma (NHL) patients. The impact of the dose intensity of busulfan on outcomes has not been reported yet. PATIENTS AND METHODS: This was a retrospective with the aim to compare the outcomes of NHL patients who received before allo-SCT a fludarabine/busulfan conditioning regimen, either of reduced intensity (FB2, 2 days of busulfan at 4 mg/kg/day oral or 3.2 mg/kg/day i.v.) (n = 277) or at a myeloablative reduced-toxicity dose (FB3/FB4, 3 or 4 days of busulfan at 4 mg/kg/day oral or 3.2 mg/kg/day i.v.) (n = 101). RESULTS: In univariate analysis, the 2-year overall survival (FB2 66.5% versus 60.3%, P = 0.33), lymphoma-free survival (FB2 57.9% versus 49.8%, P = 0.26), and non-relapse mortality (FB2 19% versus 21.1%, P = 0.91) were similar between both groups. Cumulative incidence of grade III-IV acute graft versus host disease (GVHD) (FB2 11.2% versus 18%, P = 0.08), extensive chronic GVHD (FB2: 17.3% versus 10.7%, P = 0.18) and 2-year GVHD free-relapse free survival (FB2: 44.4% versus 42.8%, P = 0.38) were also comparable. In multivariate analysis there was a trend for a worse outcome using FB3/FB4 regimens (overall survival: HR 1.47, 95% CI: 0.96-2.24, P = 0.08; lymphoma-free survival: HR: 1.43, 95% CI: 0.99-2.06, P = 0.05; relapse incidence: HR 1.54; 95% CI: 0.96-2.48, P = 0.07). These results were confirmed using a propensity score-matching strategy. CONCLUSION: We conclude that reduced toxicity myeloablative conditioning with fludarabine/busulfan does not improve the outcomes compared with reduced-intensity conditioning in adults receiving allo-SCT for NHL.

Detection of regulated herbs and plants in plant food supplements and traditional medicines using infrared spectroscopy.

The identification of a specific toxic or regulated plant in herbal preparations or plant food supplements is a real challenge, since they are often powdered, mixed with other herbal or synthetic powders and compressed into tablets or capsules. The classical identification approaches based on micro- and macroscopy are therefore not possible anymore. In this paper infrared spectroscopy, combined with attenuated total reflectance was evaluated for the screening of plant based preparations for nine specific plants (five regulated and four common plants for herbal supplements). IR and NIR spectra were recorded for a series of self-made triturations of the targeted plants. After pretreatment of the spectral data chemometric classification techniques were applied to both data sets (IR and NIR) separately and the combination of both. The results show that the screening of herbal preparations or plant food supplements for specific plants, using infrared spectroscopy, is feasible. The best model was obtained with the Mid-IR data, using SIMCA as modelling technique. During validation of the model, using an external test set, 21 of 25 were correctly classified and six of the nine targeted plants showed no misclassifications for the selected test set. For the other three a success rate of 50% was obtained. Mid-IR combined with SIMCA can therefore be applied as a first step in the screening of unknown samples, before applying more sophisticated fingerprint approaches or identification tests described in several national and international pharmacopoeia. As a proof of concept five real suspicious samples were successfully screened for the targeted regulated plants.

The use of Stationary Phase Optimized Selectivity Liquid Chromatography for the development of herbal fingerprints to detect targeted plants in plant food supplements.

The consumption of plant food supplements is increasing steadily and more and more, these products are bought through internet. Often the products sold through internet are not registered or declared with a national authority, meaning that no or minimal quality control is performed and that they could contain herbs or plants that are regulated. Stationary Phase Optimized Selectivity Liquid Chromatography (SOS-LC) was evaluated for the development of specific fingerprints, to be used for the detection of targeted plants in plant food supplements. Three commonly used plants in plant food supplements and two regulated plants were used to develop fingerprints with SOS-LC. It was shown that for all plants specific fingerprints could be obtained, allowing the detection of these targeted plants in triturations with different herbal matrices as well as in real samples of suspicious supplements seized by the authorities. For three of the five plants a more specific fingerprint was obtained, compared to the ones developed on traditional columns described in literature. It could therefore be concluded that the combination of segments of different types of stationary phases, as used in SOS-LC, has the potential of becoming a valuable tool in the quality control and the identification of crude herbal or plant material and in the detection of regulated plants in plant food supplements or other herbal preparations.

Chemometrics and chromatographic fingerprints to classify plant food supplements according to the content of regulated plants.

Plant food supplements are gaining popularity, resulting in a broader spectrum of available products and an increased consumption. Next to the problem of adulteration of these products with synthetic drugs the presence of regulated or toxic plants is an important issue, especially when the products are purchased from irregular sources. This paper focusses on this problem by using specific chromatographic fingerprints for five targeted plants and chemometric classification techniques in order to extract the important information from the fingerprints and determine the presence of the targeted plants in plant food supplements in an objective way. Two approaches were followed: (1) a multiclass model, (2) 2-class model for each of the targeted plants separately. For both approaches good classification models were obtained, especially when using SIMCA and PLS-DA. For each model, misclassification rates for the external test set of maximum one sample could be obtained. The models were applied to five real samples resulting in the identification of the correct plants, confirmed by mass spectrometry. Therefore chromatographic fingerprinting combined with chemometric modelling can be considered interesting to make a more objective decision on whether a regulated plant is present in a plant food supplement or not, especially when no mass spectrometry equipment is available. The results suggest also that the use of a battery of 2-class models to screen for several plants is the approach to be preferred.

Paecilomyces variotii Fungemia in a Patient with Lymphoma Needing Liver Transplant.

Paecilomyces sp. are emerging pathogens in immunocompromised patients. We report here a case of Paecilomyces variotii fungemia, cured with amphotericin and anidulafungin, illustrating difficulties of early diagnosis and therapeutic choice in such rare fungal infection.

Chromatographic fingerprinting as a strategy to identify regulated plants in illegal herbal supplements.

Erectile dysfunction (ED) is a sexual disorder characterized by the inability to achieve or maintain a sufficiently rigid erection. Despite the availability of non-invasive oral treatment options, many patients turn to herbal alternatives. Furthermore, herbal supplements are increasingly gaining popularity in industrialized countries and, as a consequence, quality control is a highly important issue. Unfortunately, this is not a simple task since plants are often crushed and mixed with other plants, which complicates their identification by usage of classical approaches such as microscopy. The aim of this study was to explore the potential use of chromatographic fingerprinting to identify plants present in herbal preparations intended for the treatment of ED. To achieve this goal, a HPLC-PDA and a HPLC-MS method were developed, using a full factorial experimental design in order to acquire characteristic fingerprints of three plants which are potentially beneficial for treating ED: Epimedium spp., Pausinystalia yohimbe and Tribulus terrestris. The full factorial design demonstrated that for all three plant references a C8 column (250mm×4.6mm; 5µm particle size) is best suited; methanol and an ammonium formate buffer (pH 3) were found to be the best constituents for the mobile phase. The suitability of this strategy was demonstrated by analysing several self-made triturations in three different botanical matrices, which mimic the influential effects that could be expected when analysing herbal supplements. To conclude, this study demonstrates that chromatographic fingerprinting could provide a useful means to identify plants in a complex herbal mixture.

Clustering and diagnostic modelling of slimming aids based on chromatographic and mass spectrometric fingerprints.

Herbal medicines and food supplements intended as slimming aids are increasingly gaining popularity worldwide, especially for treating obesity. In this study, an ultra-performance liquid chromatography coupled to photodiode array detection (UPLC-PDA) and an ultra-performance liquid chromatography mass spectrometry (UPLC-MS) method were developed to analyze 92 slimming aids (confiscated by customs), aimed at acquiring highly informative fingerprints. Three types of fingerprints were acquired (PDA, Total Ion Chromatograms (TIC), and MS fingerprints) which were used in the chemometric data analysis. Both unsupervised (i.e., Hierarchical Cluster Analysis (HCA)) and supervised techniques (i.e., Classification and Regression Tree (CART) and Partial Least Squares - Discriminant Analysis (PLS-DA)) were applied. The aim was to perform an in-depth study of the samples, thereby exploring potential patterns present in the data. HCA was able to generate a clustering which was mainly defined by chemical compounds detected in the samples, i.e., sibutramine, phenolphthalein and amfepramone. PLS-DA generated the best diagnostic models for both PDA and TIC fingerprints, characterized by correct classification rates of external validation of 85% and 80%, respectively. For the MS fingerprints, the best model was obtained by CART (65% correct classification rate of external validation). Despite a lower correct classification rate, exploration of the concerned misclassifications revealed that the MS fingerprints proved to be superior since even very low concentrations of sibutramine could be detected. This study shows that reliable chemometric models can be obtained, based on the presence of prohibited chemical substances, which allow high-throughput data analysis of such samples. Moreover, they generate a prime notion of potential threat to a patient's health posed by these kinds of slimming aids. Copyright © 2016 John Wiley & Sons, Ltd.

Chemometrics and the identification of counterfeit medicines-A review.

This review article provides readers with a number of actual case studies dealing with verifying the authenticity of selected medicines supported by different chemometric approaches. In particular, a general data processing workflow is discussed with the major emphasis on the most frequently selected instrumental techniques to characterize drug samples and the chemometric methods being used to explore and/or model the analytical data. However, further discussion is limited to a situation in which the collected data describes two groups of drug samples - authentic ones and counterfeits.

Exposure to hypomethylating agent, 5-azacytidine, may improve iCasp9 suicide gene therapy for treating GvHD in allografts.

Anti-tumor cellular immunotherapies that implement a suicide gene system can limit potential undesirable effects. In a haplo-identical bone marrow transplant clinical trial, over 90% of iCaspase-9-expressing cells were eradicated after AP1903 exposure, and signs of graft-versus-host disease disappeared. Nevertheless, low numbers of genetically modified T cells survived this treatment. We studied genetically modified cell lines (GMCL) that carried a dual iCaspase-9/ΔCD19 DNA construct (ΔCD19=truncated CD19). With AP1903 exposure, a low percentage of cells (1.47±0.67%; n=5 replications) persisted in vitro. Repeated exposures to increasing AP1903 doses generated low (GMCLLR) and high AP1903-responders (GMCLHR), which expressed different levels of surface ΔCD19 and intracellular iCaspase-9. Compared with GMCLHR, GMCLLR exhibited higher methylation of 5'-long-terminal repeat (LTR) promoters, both in the number of sequences with at least one methylated CpG (16 vs 51.5%, respectively) and in the number of CpG islands (1.2 vs 8.9%, respectively). Four days of 5-azacytidine exposure reduced methylation and increased ΔCD19 and iCaspase-9 expression. Interestingly, LTR demethylation restored GMCLLR sensitivity to AP1903 by 24.3-fold (1.8 vs 43.8%) without affecting GMCLHR. We showed that 5'-LTR-methylation inhibited transgene expression and caused AP1903 hypo-responsiveness. Treating with a hypomethylating agent restored AP1903 sensitivity. This approach can be applied in further clinical trials to improve iCaspase-9 response if low response is detected.