ABCB1 Single Nucleotide Polymorphisms Research Articles

Detection of Tri-allelic Single Nucleotide Polymorphisms of ABCB1 and CRP Genes by Penta-Primer Amplification Refractory Mutation System-Polymerase Chain Reaction.

Objective: The standard methods for tri-allelic single nucleotide polymorphism (SNP) genotyping require special equipment and are costly to perform. The aim of this study was to establish a fast, simple, and low-cost method to differentiate among tri-allelic SNPs in general laboratories. Methods: Based on the tetra-primer amplification refractory mutation system-polymerase chain reaction (T-ARMS-PCR) typing of bi-allelic SNPs, we developed a penta-primer amplification refractory mutation system-polymerase chain reaction (P-ARMS-PCR) method characterize tri-allelic SNPs. The two most studied tri-allelic SNPs, rs2032582 and rs3091244, were genotyped using P-ARMS-PCR in 110 volunteers, and the results were verified by direct DNA sequencing. Results: For rs2032582, there were 20 samples (18.18%) with the GG genotype, 3 (2.73%) with the AA genotype, 24 (21.82%) with the TT genotype, 43 (39.09%) with the GT genotype, 11 (10.00%) with the AG genotype, and 9 (8.18%) with the AT genotype. For rs3091244, there were 67 samples (60.91%) with the CC genotype, 1 (0.91%) with the AA genotype, 8 (7.27%) with the CT genotype, 31 (28.18%) with the CA genotype, and 3 (2.73%) with the AT genotype. The genotypic distributions of rs2032582 (p = 0.482) and rs3091244 (p = 0.492) were in Hardy-Weinberg equilibrium. The DNA sequencing results were entirely consistent with the results of P-ARMS-PCR. Conclusion: P-ARMS-PCR is an accurate, rapid, simple, and low-cost characterization method for tri-allelic SNP genotyping of rs2032582 and rs3091244.

Common ABCB1 SNP, C3435T could affect systemic exposure of dapagliflozin in healthy subject.

P-glycoprotein (P-gp) is a transporter that plays an excretory role in epithelial cells. It is encoded by ABCB1, and single nucleotide polymorphisms (SNPs) in this gene can affect systemic drug exposure. Dapagliflozin and sitagliptin, used in type 2 diabetes treatment, are P-gp substrates. Here, we aimed to investigate whether ABCB1 polymorphisms affect dapagliflozin and sitagliptin pharmacokinetics (PK) in healthy Korean subjects. The study population consisted of 100 healthy Korean subjects (94 men and 6 women) who participated in four different clinical trials and received dapagliflozin and sitagliptin doses of 10 and 100 mg, respectively. We determined ABCB1 genotypes for the C3435T, C1236T, and G2677T/A SNPs. The relationship between the genotypes and dapagliflozin PKs was examined. Dapagliflozin and sitagliptin PK parameters were not statistically significantly affected by ABCB1 SNP genotypes. However, homozygous 3435TT subjects showed higher dapagliflozin PK parameters than CT and CC subjects. In subjects with the 3435TT and those with 3435CC and 3435CT genotypes, mean Cmax, AUCinf, and AUC0-1 values of dapagliflozin were 223.06 ng/mL and 194.81 ng /mL (p = 0.2767), 673.58 ng*h/mL and 573.96 ng*h/mL (p = 0.0492), and 128.53 ng*h/mL and 104.61 ng*h/mL (p = 0.2678), respectively. In summary, dapagliflozin and sitagliptin PK parameters were not significantly different between individuals with C1236T and C2677T/A ABCB1 genetic polymorphisms. Dapagliflozin exhibited higher systemic exposure in 3435TT subjects than in CC/CT subjects.

Effect of Polymorphisms of ABCB1 and MTHFR on Methotrexate-Related Toxicities in Adults With Hematological Malignancies

Study of the association between single nucleotide polymorphisms (SNPs) of methotrexate (MTX) pathway genes and MTX-related toxicity in the treatment of hematological malignancies is popular. Here, we studied the association between SNPs of MTHFR and ABCB1 and MTX-related toxicity in 157 adult Chinese patients diagnosed with hematological malignancies. Patients were genotyped for MTHFR rs1801131, MTHFR rs1801133, and ABCB1 rs1045642 by fluorescence in situ hybridization. Patients with MTHFR rs1801133T allele had a significantly higher risk of hematopoietic toxicity compared with those with CC genotype (p=0.003). With respect to MTHFR rs1801131, patients with CC and AC genotypes had significantly lower frequency of hematopoietic toxicity than patients with AA genotype (p=0.044). In conclusion, we identified an important influence of the SNPs of ABCB1 and MTHFR on MTX-related hematopoietic toxicity in adults with hematological malignancies. To optimize high-dose (HD)-MTX therapy and reduce related hematopoietic toxicity, it is necessary to detect the SNPs of MTHFR and ABCB1 before initiating HD-MTX and deciding the optimal dose of MTX and duration of leucovorin rescue, according to genetic tests and disease type in adults with hematological malignancies.

Clinical utility of ABCB1 single nucleotide polymorphism on tacrolimus dose requirements in Egyptian liver transplant patients

BackgroundLiver transplantation (LT) is the only effective radical cure for all types of end-stage liver diseases. Major advances have been made in the field of liver transplantation due to improvements in surgical techniques and organ conservation as well as optimization of intensive care and immunosuppressive management. We aimed to assess the influence of ABCB1 gene polymorphism of liver transplant recipients on blood level and dose requirements of oral tacrolimus, in an attempt to help in designing an individualized tacrolimus regimen for Egyptian liver transplant recipient. The study included 25 liver transplant recipients and their respective 25 donors. All subjects of this study were subjected to full medical history, clinical evaluation, laboratory investigations, and ABCB1 gene polymorphism evaluation by RT-PCR. Tacrolimus concentration was evaluated for all the recipients during the first 3 months post transplantation.ResultsThe present study revealed that the presence of CC genotype was significantly correlated to the effect on tacrolimus C/D ratio and weight-adjusted tacrolimus dose during the first week of the first and 2nd months (Z = −2.108, P <0.05) but not the 3rd month post transplantation (p-value >0.05). Subjects carrying CC genotype required higher doses of tacrolimus to achieve the desired trough levels compared to subjects carrying CT and TT genotypes. The same effect was observed over the whole period of the study but the results were statistically non-significant (p-value>0.05). Recipients who received liver tissue from donors carrying CC genotype also required higher doses of tacrolimus and reached lower levels of blood tacrolimus trough levels.ConclusionThe present study revealed that ABCB1 CC genotype of both recipients and donors of liver transplantation was significantly associated with increased required tacrolimus dose early after liver transplantation reaching statistically significant level in the first week of the first and second months.

Drug Transporter ABCB1 SNP Predicts Outcome in Patients with Acute Myeloid Leukemia Treated with Gemtuzumab Ozagamicin: A Report from Children's Oncology Group AAML0531 Trial

Background: Gemtuzumab Ozogamicin (GO), is first ever approved immunotherapy for relapsed AML patients. GO is a humanized anti-CD33 antibody linked with the toxin calicheamicin gamma. Calicheamicin induces DNA damage and cell death once the linked CD33 antibody facilitates its uptake. Previous studies have shown that the drug efflux transporter PgP1, which is encoded by gene ABCB1, influences the cellular accumulation of calicheamicin. PgP1 activity in leukemic cells is also inversely correlated with GO response in patients with AML. Although GO was withdrawn from market due to lack of benefit and increase in early mortality observed in SWOG-S0106 study subsequent multiple randomized studies have shown benefit of GO with significant improvement observed in patients with favorable cytogenetic risk features. In light of these results and recent favorable voting by FDA oncology drug advisory committee based on results of ALFA-0701 trail demonstrating a favorable risk:benefit profile for GO there is increased enthusiasm among AML investigators. Given the potential comeback of GO, it is very timely to focus efforts on identifying genetic biomarkers that can improve our ability to develop personalized treatment with GO. In this study evaluate whether single nucleotide polymorphisms (SNPs) in ABCB1 gene are predictive of GO response in patients with AML.Method: Genomic DNA samples from 942 patients enrolled in the COG trial AAML0531 who gave consent for the study were genotyped for 12 SNPs in the ABCB1 gene . Since AAML0531 was designed to test the benefit of GO in a randomized manner, we analyzed the effect of ABCB1 genotypes on outcomes and risk of relapse (RR) between patients treated with or without addition of GO (GO vs. No-GO respectively).Results: The ABCB1 SNP C3435T (rs1045642) was significantly associated with outcome when analyzed by GO vs. No-GO arm. Presence of C3435T change has been previously associated with lower PgP1 expression. For AML patients in the GO arm, presence of variant allele (CT and TT genotype) was significantly associated with lower risk of relapse (RR) from the end of course 1 (GO vs. No-GO arm: RR: 30 ± 6%, n = 259 vs. 46 ± 7%, n= 235; P < 0.0001) and better 5-year event free survival (EFS) from study than for those in the No-GO arm (GO vs. No-GO arm: 55 ± 6%, n = 340 vs. 45 ± 5%, n= 337; P= 0.006). However, patients with the CC genotype showed no differences in RR (GO and No-GO arms: 45 ± 10%, n = 97 vs. 40 ± 11%, n= 91; P= 0.514) and EFS (GO and No-GO arms: 44 ± 9%, n = 128 vs. 50 ± 9%, n= 132; P= 0.425) between the GO and No-GO arms (Fig 1). Further the rs1045642 genotype was significantly associated with EFS (CC vs. CT/TT: 44 ± 9% vs. 55 ± 6%; P=0.022) and RR (CC vs. CT/TT 45 ± 10% vs. 30 ± 6%, P=0.007) for patients in the GO arm but for those in the No-GO arm no difference in outcome between the genotypes was observed (RR: P=0.278; EFS P=0.466).Conclusion: Our results show that for the nonsynonymous SNP rs1045642 (C>T) in an drug efflux transporter ABCB1, the presence of T allele is associated with better response in patients treated with GO based as compared to standard arm. Since ABCB1 is involved in efflux of calicheamicin the presence of a low expression T allele might result in higher intracellular accumulation of calicheamicin and thus better response in patients treated with GO. [Display omitted] DisclosuresLoken:Hematologics Inc: Employment, Equity Ownership. Walter:ADC Therapeutics: Research Funding; Aptevo Therapeutics: Research Funding.

ABCB1 polymorphism in clopidogrel-treated Montenegrin patients.

Clopidogrel is an antiplatelet drug that displays significant interindividual variability in treatment response. Its bioavailability depends on the function of P-glycoprotein (P-gp), which is coded by a highly polymorphic ABCB1 gene. Thus, the aim of this study was to investigate the effect of ABCB1 genetic polymorphism on clopidogrel efficacy and safety and to determine the frequency distribution of its most common single nucleotide polymorphisms (SNPs) in 106 Montenegrin cardiology patients. Clopidogrel efficacy and safety were followed up during 1 year after hospitalization, with the lack of efficacy and adverse drug reactions observed in 11 (10.4%) and 8 patients (7.5%), respectively. Genotyping for ABCB1 SNPs rs1128503 (1236C > T), rs2032582 (2677G > A/T), and rs1045642 (3435C > T) was performed by the real-time PCR method, and the variant alleles were detected with the frequencies of 42.9, 44.8, and 52.8%, respectively. No significant association was observed between any of the examined genotypes and clopidogrel efficacy (p = 0.253) or safety (p = 0.424). Due to small sample size, co-treatment with other drugs, and other genetic factors not taken into account, we believe the absence of correlation between ABCB1 genotypes and indicators of clopidogrel efficacy and safety in this study should be apprehended conditionally, and that larger and better-controlled studies are warranted.

Pharmacogenetics of Direct Oral Anticoagulants: A Systematic Review.

Dabigatran, rivaroxaban, apixaban, edoxaban, and betrixaban are direct oral anticoagulants (DOACs). Their inter-individual variability in pharmacodynamics and pharmacokinetics (transport and metabolism) is high, and could result from genetic polymorphisms. As recommended by the French Network of Pharmacogenetics (RNPGx), the management of some treatments in cardiovascular diseases (as antiplatelet agents, oral vitamin K antagonists, and statins) can rely on genetic testing in order to improve healthcare by reducing therapeutic resistance or toxicity. This paper is a review of association studies between single nucleotide polymorphisms (SNPs) and systemic exposure variation of DOACs. Most of the results presented here have a lot to do with some SNPs of CES1 (rs2244613, rs8192935, and rs71647871) and ABCB1 (rs1128503, rs2032582, rs1045642, and rs4148738) genes, and dabigatran, rivaroxaban, and apixaban. Regarding edoxaban and betrixaban, as well as SNPs in the CYP3A4 and CYP3A5 genes, literature is scarce, and further studies are needed.

Influence of ABCB1 gene polymorphism on concentration to dose ratio and adverse effects of tacrolimus in Pakistani liver transplant recipients.

Objective:To evaluate the possible association of ABCB1 single nucleotide polymorphism (SNPs) of the ABCB1 gene with tacrolimus dosages, concentration-to-dose ratios (CDR) and adverse effects in Pakistani liver transplant recipients.Methods:This observational study was conducted at Shifa International Hospital, Shifa Tameer-e-Millat University, Islamabad and Basic Medical Sciences Institute, Karachi from September 2016 to July 2020. Eighty-one liver transplant recipients were included. Demographics, clinical data, tacrolimus trough levels and doses were monitored. Electrochemiluminescence immunoassay (ECLIA) was used to measure tacrolimus trough levels. Transplant recipients were genotyped for three ABCB1 SNPs (rs1045642, rs2032582 and rs1128503). Acute cellular rejection (ACR), sepsis and other adverse events were monitored.Results:ABCB1 rs1045642 CC genotype showed lower tacrolimus CDR as compared to CT and TT genotype in the first week of the post-transplantation period (p=0.02). There was a significant association of polymorphisms in rs1045642, rs2032582 and rs1128503 with psychosis, sepsis and ACR respectively.Conclusion:Identification of ABCB1 rs1045642 polymorphism may shorten the time to achieve optimum levels of tacrolimus during dose titration. ABCB1 polymorphism rs1045642, rs2032582 and rs1128503 may predict adverse effects in liver transplant recipients receiving tacrolimus.

GSTP1 and ABCB1 Polymorphisms Predicting Toxicities and Clinical Management on Carboplatin and Paclitaxel-Based Chemotherapy in Ovarian Cancer.

Variation in drug disposition genes might contribute to susceptibility to toxicities and interindividual differences in clinical management on chemotherapy for epithelial ovarian cancer (EOC). This study was designed to explore the association of GST and ABCB1 genetic variation with hematologic and neurologic toxicity, changes in chemotherapy, and disease prognosis in Brazilian women with EOC. A total of 112 women with a confirmed histological diagnosis of EOC treated with carboplatin/paclitaxel were enrolled (2014–2019). The samples were analyzed by multiplex polymerase chain reaction (PCR) for the deletion of GSTM1 and GSTT1 genes. GSTP1 (c.313A>G/rs1695) and ABCB1 (c.1236C>T/rs1128503; c.3435C>T/rs1045642; c.2677G>T>A/rs2032582) single nucleotide polymorphisms (SNPs) were detected by real‐time PCR. Subjects with the GSTP1 c.313A>G had reduced risk of anemia (odds ratio (OR): 0.17, 95% confidence interval (CI): 0.04–0.69, P = 0.01, dominant model) and for thrombocytopenia (OR: 0.27, 95% CI: 0.12–0.64, P < 0.01; OR 0.18, 95% CI 0.03–0.85, P = 0.03, either dominant or recessive model), respectively. The GSTP1 c.313A>G AG genotype was associated with a lower risk of dose delay (OR: 0.35, 95% CI: 0.13–0.90, P = 0.03). The ABCB1 c.1236C>T was associated with increased risk of thrombocytopenia (OR: 0.15, 95% CI: 0.03–0.82, P = 0.03), whereas ABCB1 c.3435C>T had increased risk of grade 2 and 3 neurotoxicity (OR: 3.61, 95% CI: 1.08–121.01, P = 0.03) in recessive model (CC + CT vs. TT). This study suggests that GSTP1 c.313A>G, ABCB1 c.1236C>T, and c.3435C>T SNP detection is a potential predictor of hematological toxicity and neurotoxicity and could help predict the clinical management of women with EOC.

Impact of combinations of single-nucleotide polymorphisms of anthracycline transporter genes upon the efficacy and toxicity of induction chemotherapy in acute myeloid leukemia

Anthracycline uptake could be affected by influx and efflux transporters in acute myeloid leukemia (AML). Combinations of single-nucleotide polymorphisms (SNPs) of wild-type genotype of influx transporters (SLC22A16, SLCO1B1) and homozygous variant genotypes of ABC polymorphisms (ABCB1, ABCC1, ABCC2, ABCG2) were evaluated in 225 adult de novo AML patients. No differences in complete remission were reported, but higher induction death was observed with combinations of SLCO1B1 rs4149056 and ABCB1 (triple variant haplotype, rs1128503), previously associated with ABCB1 and SLCO1B1 SNPs. Several combinations of SLCO1B1 and SLC22A16 with ABCB1 SNPs were associated with higher toxicities, including nephrotoxicity and hepatotoxicity, neutropenia, previously related to ABCB1, and a novel correlation with mucositis. Combination of SLC22A16 rs714368 and ABCG2 rs2231142 was related to cardiac toxicity, reproducing previous correlations with ABCG2. This study shows the impact of transporter polymorphisms in AML chemotherapy safety. Further prospective studies with larger populations are needed to validate these associations.

Impact of CYP2C19, CYP3A4, ABCB1, and FMO3 genotypes on plasma voriconazole in Thai patients with invasive fungal infections.

Voriconazole is the first‐line antifungal choice in the treatment of invasive fungal infections (IFIs). Single nucleotide polymorphisms (SNPs) in drug‐metabolizing and transporter genes may affect voriconazole pharmacokinetics. This study aimed to determine the frequency of the CYP2C19 rs4244285, rs4986893, rs72552267, and rs12248560, CYP3A4 rs4646437, ABCB1 rs1045642, and FMO3 rs2266782 alleles and determine the association between these genetic variants and voriconazole concentrations in Thai patients with invasive fungal infections. The study comprised 177 Thai patients with IFIs in whom seven SNPs in CYP2C19, CYP3A4, ABCB1, and FMO3 were genotyped using TaqMan real‐time polymerase chain reaction (RT‐PCR) 5´ nuclease assays, and voriconazole plasma concentrations were measured by high‐performance liquid chromatography‐tandem mass spectrometry (LC‐MS/MS). Of the 177 patients included, 31 were <12 years and 146 were ≥12 years. The CYP2C19 allele frequencies were 0.29 for *2, 0.060 for *3, 0.003 for *6, and 0.008 for *17. The allele frequency of CYP3A4 (rs4646437) was 0.26, ABCB1 (rs1045642) was 0.36, and FMO3 (rs2266782) was 0.16. The median voriconazole dose/weight was significantly lower in patients aged ≥12 years when compared to the patients aged <12 years (P < .001). Patients aged <12 years with CYP2C19*1/*2 exhibited significantly higher median voriconazole plasma concentrations than those with the CYP2C19*1/*1 (P = .038). However, there were no significant differences in median voriconazole plasma concentrations among the CYP2C19 genotypes in the patients aged ≥12 years. There was a lack of association observed among the CYP3A4, ABCB1, and FMO3 genotypes on the plasma voriconazole concentrations in both groups of patients. Our findings indicate that voriconazole plasma concentrations are affected by the CYP2C19*2 allele in patients aged <12 years but not in patients aged ≥12 years.

379P Impact of MGMT and ABCB1 single nucleotide polymorphisms on temozolomide-induced thrombocytopenia in newly diagnosed glioblastoma

Chemo-induced thrombocytopenia is a limiting adverse event in glioblastoma patients receiving temozolomide (TMZ). Constitutional single nucleotide polymorphisms (SNP) of genes involved in the pharmacodynamics and pharmacokinetics of TMZ were described to be associated with increased risk of TMZ-induced myelotoxicity in retrospective cohorts. We prospectively investigate the risk of thrombocytopenia (<100G/L) regarding MGMT rs2308327 and ABCB1 rs1045642. A total of 100 newly-diagnosed glioblastoma patients, receiving standard treatment (concomitant TMZ and radiotherapy [RT] followed by TMZ maintenance phase), were included in the study. Loss of function allelic variants rs2308327 of the MGMT gene; and rs1045642 of the ABCB1 gene were characterized using Taqman® PCR. Using univariate and multivariate logistic regression we investigated the association between SNPs and TMZ-induced thrombocytopenia occurrence along first-line treatment schedule and overall survival. This study is ancillary to the ongoing prospective phase 2 GLIOPLAK trial (NCT02617745). Overall, 23/100 patients experienced TMZ-induced thrombocytopenia: 11 patients during the RT-TMZ phase and 12 other patients during the TMZ maintenance phase. Among them, 7 patients experienced severe thrombocytopenia <50 G/l. Observed allele frequencies were in accordance with those reported for Caucasians (11% for MGMT rs2308327 and 47.5% for ABCB1 rs1045642). Harboring rs2308327 or rs1045642 was not associated with TMZ-induced thrombocytopenia: odds ratio (OR) 1.1 [CI 95% 0.3-3.2, p=0.56] and OR 1.01 [0.49-2.09, p=0.55] respectively. Severe thrombocytopenia (<50 G/L, n=7 patients) were not associated with any of the two SNPs. Wild-type versus heterozygous or homozygous SNP did not influence overall survival, log-rank test p=0.19 and p=0.34 respectively. Occurrence of thrombocytopenia <100 G/l induced an underexposure to TMZ in maintenance phase: median 3 cycles vs 5 in the no thrombocytopenia group. rs2308327 and rs1045642 were not associated with TMZ-related thrombocytopenia in a prospective population of glioblastoma.

Distribution of CYP2C19, ABCB1 and PON1 polymorphisms in Chinese Han, Hui, Uygur and Kazak patients with coronary atherosclerotic heart disease.

CYP2C19, ABCB1 and PON1 polymorphisms involve in the metabolism and absorption of clopidogrel, which may be associated with interethnic variability of clopidogrel response. In our study, we evaluated the prevalence of CYP2C19, ABCB1 and PON1 single nucleotide polymorphisms (SNP) in patients with coronary atherosclerotic heart disease (CHD) of Chinese Han, Hui, Uygur and Kazak ethnic groups. Five SNPs were detected [CYP2C19 ∗2 (rs4244285), CYP2C19 ∗3 (rs4986893), CYP2C19 ∗17 (rs12248560), ABCB1 (rs1045642) and PON1 (rs662)]. The analysis was performed in 1,337 patients with CHD, including 831 Han, 85 Hui, 352 Uygur and 69 Kazak. The results revealed the differential distribution of the five SNPs. Frequencies of CYP2C19 no function variants in Uygur and Kazak were lower than those in Han and Hui groups (P<.05). CYP2C19 variants with increased function were more common in Uygur (13.6%) and Kazak (10.9%) groups (P<.05). Compared with Han and Hui groups, distribution of ABCB1 allele T was more prevalent in Uygur and Kazak groups (53.8% and 50.7%, respectively, P<.05). PON1 allele A frequencies of 55.7% and 58.7% in Uygur and Kazak showed higher prevalence than in the Han (38.4%) and Hui (43.5%) groups (P<.05). In conclusion, CYP2C19 *2 and *3 alleles are prevalent in Chinese Han and Hui groups, whereas CYP2C19 *17, ABCB1 T and PON1 A variants are relatively frequent in Chinese Uygur and Kazak ethnic groups. Our findings may provide a theoretical basis for the explanation of ethnic differences in determining clinical therapy strategies and predicting adverse effects.

ABCB1 and ERCC1 gene polymorphisms are associated with nephro- and hepatotoxicity to carboplatin/paclitaxel-based chemotherapy in patients with gynecologic cancers.

Paclitaxel/carboplatin combination is the standard chemotherapeutic protocol for gynecologic cancers, but severe toxicities may compromise treatment. There is great inter-individual variability regarding the incidence and severity of toxicities, which may be due to single-nucleotide polymorphisms (SNPs) affecting drug disposition or cellular sensitivity. Here we investigate the impact of selected SNPs in ERCC1, ABCB1, CYP2C8, and CYP3A5 genes on the incidence of severe toxicities, including nephro- and hepatotoxicity. A cohort of 507 gynecological cancer patients receiving paclitaxel/carboplatin was recruited at the Brazilian National Cancer Institute (INCA-Brazil). Clinical data were obtained during routine consultations or from electronic medical records. Toxicities were graded according to the Common Terminology Criteria for Adverse Events (CTCAE 5.0). Genotyping was performed using real-time PCR. ABCB1 c.1236C>T was associated with moderate-to-severe (grades 2-4) nephrotoxicity (ORadjusted 2.40; 95% CI 1.39-4.15), even after adjustment for age (≥ 65) and diabetes. The risk association between ABCB1 c.1236C>T and moderate-to-severe nephrotoxicity following paclitaxel/carboplatin chemotherapy was also present among non-diabetic patients (ORadjusted 2.16; 95% CI 1.22-3.82). ERCC1 c.118C>T was the only individual variable associated with an increased risk for moderate-to-severe (grades 2-4) hepatotoxicity (OR 3.71; 95% CI 1.08-12.77), severe nausea (OR 4.18; 95% CI 1.59-10.95), and severe myalgia (OR 1.95; 95% CI 1.12-3.40). ABCB1 c.1236C>T and ERCC1 c.118C>T might serve as potential biomarkers for the risk of moderate-to-severe toxicities to carboplatin/paclitaxel chemotherapy of gynecological cancers.

Abstract P5-06-30: Identification of novel single nucleotide polymorphisms located in MAP3K1 and ABCB1 genes as markers for poor overall survival in early-stage hormone receptor-positive breast cancer using next-generation sequencing

Abstract Background: We previously revealed that single nucleotide polymorphisms (SNPs) of CYP19A1, MAP3K1 rs889312, and ABCB1 rs2032582 were associated with overall survival (OS) in early-stage hormone receptor (HR)-positive breast cancer patients. Previous studies also showed that FGFR2 rs1219468 and TOX3 rs8051542 influenced OS in early-stage breast cancer patients. In this study, we assessed whether undiscovered SNPs of CYP19A1, MAP3K1, ABCB1, FGFR2, and TOX3 are associated with clinical outcome of patients with early-stage HR-positive breast cancer. Patients and Methods: We used next-generation sequencing (NGS) methods to explore unidentified SNPs of CYP19A1, MAP3K1, ABCB1, FGFR2, and TOX3 in 80 patients who had HR+, T1 to T2, and N0 to N1 breast cancer and had matched clinicopathological features and clinical outcomes (experimental cohort). The mapping selected SNPs identified from NGS were located in different chromosomes, such as chromosome 5 (MAP3K), 7 (ABCB1), 10 (FGFR2), 15 (CYP19A1), and 16 (TOX3), were analyzed. The multivariate-adjusted hazard ratio (aHR) of OS associated with the individual genotypes of the experimental cohort was assessed after adjusting for age, tumor size, tumor grade, HER2 status, menopausal status, and chemotherapy using Cox regression analyses. We further correlated identified significant novel SNPs with disease-free survival (DFS) and OS in 195 patients with HR-positive, T1-T2, and N0-1 breast cancer (validation cohort) using stepwise selection multiple Cox model analyses. Results: Through target region re-sequencing, we identified 69 novel SNPs, including 18 CYP19A1 SNPs, 16 MAP3K SNPs, 18 ABCB1 SNPs, 12 FGFR2 SNPs, and 5 TOX3 SNPs in the experimental cohort (n = 80). After multivariate-adjusted analyzing, FGFR2 rs2981460(C/C) (p = 0.0115), and MAP3K1 rs3822625 (A/A) (p = 0.0475), rs702689 (G/G) (p = 0.0312), rs832567 (C/C) (p = 0.0312), and rs9687226 (C/C) (p = 0.0475), and ABCB1 rs2032582 (T/T+T/C) (p = 0.0061) were significantly associated with the poorer OS of the experimental cohort. In a validated cohort (n =195) (Table 1), we found that MAP3K1 rs702689 (G/G) was significantly associated with poorer DFS (aHR = 2.3; 95% confidence interval [CI] = 1.1 to 5.1; p = 0.03) and OS (aHR = 4.9; 95% CI = 1.3 to 18.7; p = 0.02). In addition, MAP3K1 rs832567 (C/C) was significantly associated with poorer DFS (aHR = 2.5; 95% CI = 1.1 to 5.5; p = 0.02) and OS (aHR = 5.4; 95% CI = 1.4 to 21.6; p = 0.02). In premenopausal women of validation cohort (n = 108), ABCB1 rs2032582 (T/T+T/C) was significantly associated with a poor OS (aHR = 62.3; 95% CI = 2.0 to 1911.7; p = 0.02). Conclusions: Our results indicate that 3 novel SNPs, MAP3K1 rs702689, MAP3K1 rs832567, and ABCB1 rs2032582, may affect the prognosis of early-stage HR-positive breast cancer. Further validation of these SNPs in a large series of patients with early-stage HR-positive breast cancer who received adjuvant endocrine therapy alone is warranted. Table 1. The Associations of Hormone Receptor-Positive Breast Cancer Patients with Various Genotypes in multiple Cox model (validation cohort)Disease-free survivalOverall survivalGenotypeaHR (95%CI)PaHR (95%CI)PTotal (n = 195)FGFR2_ rs2981460 (C/C vs.C/T+T/T)0.4 (0.1-1.8)0.220.6 (0.1-5.4)0.68MAP3K1_ rs3822625 (A/A vs. G/A+GG)2.0 (0.7-5.3)0.192.7 (0.6-12.9)0.20MAP3K1_ rs702689 (G/G vs. A/A+A/G)2.3 (1.1-5.1)0.034.9 (1.3-18.7)0.02MAP3K1_rs832567 (C/C vs. A/A+A/C)2.5 (1.1-5.5)0.025.4 (1.4-21.6)0.02MAP3K1_rs9687226 (C/C vs. T/T+T/C)2.0 (0.7-5.3)0.192.7 (0.6-12.9)0.20Premenopausal (n=108)ABCB1_rs2032582 (T/T+T/C vs. C/C)2.0 (0.8-5.0)0.1562.3 (2.0-1911.7)0.02aHR: adjusted by age, estrogen receptor and progesterone receptor status, number of lymph nodes, menopausal status, adjuvant chemotherapy, lymphovascular invasion, and tumor size. Citation Format: Sung-Hsin Kuo, Shi-Yi Yang, Po-Han Lin, Chen-Hsin Chen, Hsin-Chou Yang, Chih-Yuan Hsu, Chiun-Sheng Huang. Identification of novel single nucleotide polymorphisms located in MAP3K1 and ABCB1 genes as markers for poor overall survival in early-stage hormone receptor-positive breast cancer using next-generation sequencing [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P5-06-30.

Modification of the association between paroxetine serum concentration and SERT-occupancy by ABCB1 (P-glycoprotein) polymorphisms in major depressive disorder

Selective serotonin reuptake inhibitors (SSRIs) exert substantial variability in effectiveness in patients with major depressive disorder (MDD), with up to 50-60% not achieving adequate response. Elucidating pharmacokinetic factors that explain this variability is important to increase treatment effectiveness. To examine potential modification of the relationship between paroxetine serum concentration (PSC) and serotonin transporter (SERT)-occupancy by single nucleotide polymorphisms (SNPs) of the ABCB1 gene, coding for the P-glycoprotein (P-gp) pump, in MDD patients. To investigate the relationship between ABCB1 SNPs and clinical response. Patients had MDD and received paroxetine 20 mg/day. We measured PSC after 6 weeks. We quantified SERT-occupancy with SPECT imaging (n = 38) and measured 17-item Hamilton Depression Rating Scale (HDRS17)-scores at baseline and after 6 weeks (n = 81). We genotyped ABCB1 at rs1045642 [3435C>T], rs1128503 [1236C>T], rs2032582 [2677G>T/A] and rs2235040 [2505G>A]. For our primary aim, we modeled mean SERT-occupancy in an Emax nonlinear regression model with PSC and assessed whether the model improved by genetic subgrouping. For our secondary aim, we used multivariate linear regression analysis. The rs1128503 and rs2032582 SNPs modified the relationship between PSC and SERT-occupancy in both our intention-to-treat and sensitivity analyses at the carriership level. However, we could not detect significant differences in clinical response between any of the genetic subgroups. Pharmacokinetic influences of the ABCB1 rs1128503 and rs2032582 represent a potentially relevant pharmacogenetic mechanism to consider when evaluating paroxetine efficacy. Future studies are needed to support the role of ABCB1 genotyping for individualizing SSRI pharmacotherapy.

ABCB1 and DRD3 polymorphism as a response predicting biomarker and tool for pharmacogenetically guided clozapine dosing in Asian Indian treatment resistant schizophrenia patients.

To investigate association of two single nucleotide polymorphisms (SNPs) ABCB1(rs1045462) and DRD3(rs6280) with clozapine response and the dose in treatment resistant schizophrenia (TRS) patients. 200 TRS patients were enrolled in the study during their follow up visit post clozapine initiation. SNP assessment was performed for DRD3 (rs6280) and ABCB1(rs1045462) by sequencing. Blood sample for genotyping was collected with disease and treatment related variables recording on case record form. Patients were classified as responders or nonresponders based upon Andreasen criteria and Positive and Negative Syndrome Scale (PANSS). Mean clozapine dose, the genotype frequency distribution of ABCB1, DRD3 SNPs were significantly different in clozapine responder and non-responder study population (p < 0.05). CT genotype of ABCB1 and AG genotype of DRD3 were observed to be more prevalent in the responder group. TT genotype of ABCB1 and AG genotype of DRD3 were prevalent in the nonresponder group. Clozapine dosing equations for responder and nonresponder TRS populations were developed through logistic regression analysis. 27% variability in clozapine dose was explained by possible combinations of ABCB1 and DRD3 SNP analysis. Differential ABCB1(rs1045462) and DRD3(rs6280) genotype frequencies among the clozapine responders and non-responders explained clear feasibility of response predictor potential along with clozapine dose variability association. Pharmacogenetically guided clozapine dosing is possible if more SNPs are considered together with ABCB1(rs1045462) and DRD3(rs6280) in TRS patients.

ABCB1 Polymorphisms in High-Dose and Low-Dose Dependent Patients Under Methadone Maintenance Treatment in an Iranian Population

Background: Drug abuse is a major problem in Iran with a huge social burden. Methadone maintenance treatment (MMT) is offered as a harm reduction program to decrease the consequences of opioid drug dependence. Single nucleotide polymorphisms (SNPs) in the ABCB1 gene, encoding P-glycoprotein, have shown associations with drug uptake in the central nervous system (CNS). Objectives: We aimed to identify the frequency of ABCB1 SNPs and haplotypes in Iranian opioid-dependent patients and the link between ABCB1 haplotypes and P-glycoprotein function. Methods: We randomly selected 400 patients undergoing methadone treatment from the MMT clinics in Shahroud, Iran. Of these, 320 people qualified for the study were sorted according to their dose requirement. Individuals with a dose of greater than 100 mg/day and less than 60 mg/day were selected and divided into two groups. Blood samples were taken from 83 high-dose dependent (HDD) and 86 low-dose dependent (LDD) individuals. DNA was extracted and ABCB1 SNPs at the C1236T, C3435T, A61G, G1199A, and G2677T loci were detected using polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP). The haplotypes were obtained by the use of SNP analyzer version 2.0 software. Results: No significant differences were observed in allele and genotype frequencies of the SNPs between HDD and LDD groups. Eleven unique haplotypes were obtained, of which only the TTAGG haplotype showed a significant difference between the two populations (P = 0.030557, χ2 = 4.678). Linkage disequilibrium was observed at 1199, 1236, and 3435 loci. There were no significant differences in methadone dose requirement between different haplotypes or genotypes. Conclusions: Here, for the first time, we reported the frequency of ABCB1 SNPs in opioid-dependent people in Iran. Regarding the results, it seems that the use of these SNPs is not beneficial to predict and optimize the amount of drug requirement in Iranian society. However, further genotyping studies are required to decipher the impact of genetic variability on methadone dependence.

PB1722 IMPACT OF CD33 AND ABCB1 SINGLE NUCLEOTIDE POLYMORPHISMS IN PATIENTS WITH ACUTE MYELOID LEUKEMIA AND HIGH‐RISK MYELODYSPLASTIC SYNDROMES TREATED WITH DECITABINE PLUS GEMTUZUMAB OZOGAMICIN

Background:Single nucleotide polymorphisms (SNPs) of CD33 are predictive for relapse risk in children with acute myeloid leukemia (AML) receiving gemtuzumab ozogamicin (GO)‐containing regimens. However, the impact of CD33 SNPs on response to GO is controversial in adults. To our knowledge, no study has evaluated whether SNPs of CD33 or ABCB1, a protein that mediates GO resistance in pre‐clinical studies, predict for outcomes in patients (pts) with AML or high‐risk myelodysplastic syndromes (MDS) receiving low‐intensity therapy in combination with GO.Aims:To evaluate the impact of CD33 expression and of CD33 and ABCB1 SNPs on response, risk of relapse, and survival in pts with AML or high‐risk MDS or myelofibrosis treated in a prospective clinical trial with decitabine plus GO.Methods:Pts received decitabine 20 mg/m2 daily x 5 days plus GO 3 mg/m2 on day 5, followed by up to 5 consolidation cycles of decitabine plus GO, then decitabine alone (Daver et al. Leukemia 2016;30[2]:268‐73). Genotyping of the following SNPs was performed and correlated with clinical outcomes: ABCB1 rs1128503, ABCB1 rs1045642, CD33 rs2455069, CD33 rs35112940, CD33 rs12459419, CD33 rs1803254, CD33 rs61736475, and CD33 rs201074739. An aggregate “6 CD33 SNP score” was determined based on genotypes of the 6 CD33 SNPs, as previously described (Lamba J et al. ASH 2017, abstract 3826).Results:113 pts were treated with decitabine plus GO, 104 of whom underwent CD33 and ABCB1 SNP genotyping. Baseline characteristics of the population is shown in Table 1. For the entire cohort, 36 pts (32%) achieved any response (ORR, i.e. CR + CRi + MLFS), 16 of whom (14%) achieved CR. ORR was 47% and 18%, and CR rate was 23% and 7% for the frontline and relapsed/refractory cohorts, respectively. With a median follow‐up of 107 months, median RFS and OS were 4.8 and 10.0 months in the frontline, and 3.0 and 6.6 months in the relapsed/refractory cohorts, respectively. For the whole cohort, CD33 median fluorescence intensity (MFI) was not significantly associated with ORR, but was associated with CR (OR 1.02; P = 0.02). No individual CD33 or ABCB1 SNP was predictive for ORR or CR; however, among pts with 6 CD33 SNP score ≥0, there was a trend towards higher CR rate (21% vs. 8%, OR 3.08; P = 0.07), but not with ORR (P = 0.94). Neither CD33 MFI nor any individual genotype or the 6 CD33 SNP score were significantly associated with cumulative incidence of relapse (CIR), relapse‐free survival (RFS) or overall survival (OS). In the subgroup of pts with AML (n=91), CD33 MFI was not significantly associated with ORR, but was associated with CR (OR 1.02; P = 0.02). The GG genotype of CD33 rs1803254 (n=67) was associated with lower CIR and better RFS than the CC/CG genotypes (n=15) in the AML cohort (median RFS 5.1 versus 2.5 months, P = 0.02), although this was driven by only 3 pts with the CC/CG genotypes who responded and included in RFS analysis; there was no association with OS. No other SNP, nor the 6 CD33 SNP score, was significantly associated with CR, ORR, CIR, RFS or OS in any subgroup analyses.Summary/Conclusion:In this poor‐risk cohort of pts with MDS or AML treated with decitabine plus GO, neither CD33 MFI nor ABCB1 or CD33 SNPs were meaningfully predictive for outcomes; however, this cohort was heterogeneous and the overall efficacy of this regimen was low, which may have obscured any potential predictive value of these SNPs. Evaluation of these SNPs in pts treated with more effective low intensity regimens (e.g. hypomethylating agent plus venetoclax) in combination with GO is warranted.image

Association of drug-related polymorphisms with palbociclib-related neutropenia: Pharmacogenetic analysis of PALOMA-2/-3 (P2/3).

1060 Background: The most common PAL treatment related adverse event is neutropenia. ABCB1 and ERCC1 variants are associated with increased chemotherapy drug exposure and CYP3A7*1C may be associated with reduced exposure. Pharmacogenetic analyses of these variants in patients (pts) from P2/3 may reveal associations between single nucleotide polymorphisms (SNPs) and early occurrence of grade 3/4 (G3/4) neutropenia. Methods: ABCB1 (rs1045642, rs1128503), ERCC1 (rs3212986, rs11615), and CYP3A7*1C (rs45446698) variants were analyzed in germline DNA from pts with HR+/HER2– advanced breast cancer from P2 (n=584) and P3 (n=442) by TaqMan assay. Association between variants and incidence of G3/4 low absolute neutrophil count (ANC) at Cycle 1 Day 15 (C1D15) was assessed with the exact Cochran-Armitage trend test. Odds ratios (OR) and 95% confidence intervals (CI) were estimated by logistic regression. Results: In total, 652 PAL-treated pts had SNP, race, and C1D15 ANC data. Minor allele frequencies (MAF), incidence rates, and relative risk of G3/4 C1D15 ANC for ABCB1 and ERCC1 variants are given in the Table. CYP3A7*1C was only found in non-Asians (MAF 6%). Conclusions: This is the first comprehensive assessment of pharmacogenetic data from P2/3. ABCB1 and ERCC1 SNP allele frequencies differ between Asians and non-Asians. Despite combining P2/3 data, we lacked power to detect moderate associations; further investigation of these SNPs with G3/4 C1D15 ANC is warranted. Pfizer Clinical trial information: NCT01740427, NCT01942135. [Table: see text]