Impact of genetic polymorphisms of drug transporters ABCB1 and ABCG2 and regulators of xenobiotic transport and metabolism PXR and CAR on clinical efficacy of dasatinib in chronic myeloid leukemia.

Introduction: Functional single-nucleotide polymorphisms (SNPs) in genes regulating cellular uptake, elimination, and metabolism of xenobiotics may potentially influence the outcome of chronic myeloid leukemia (CML) patients treated with BCR-ABL1 tyrosine kinase inhibitors (TKI). Dasatinib, a second-generation TKI, is a substrate of the ABC-superfamily xenobiotic transporters ABCB1 (MDR1, Pg-P) and ABCG2 (BCRP). Pregnane X receptor (PXR, NR1I2) and constitutive androstane receptor (CAR, NR1I3) are involved in the control of expression of ABCB1 and ABCG2. Aim of the study: In this study, we assessed the impact of inherited variants in ABCB1, ABCG2, PXR, and CAR genes on dasatinib efficacy and toxicity in CML. Materials and methods: Sixty-one tagging SNPs in ABCB1, ABCG2, PXR, and CAR genes were analyzed by real-time quantitative PCR with specific probes in 86 CML patients who failed imatinib therapy. Results: We found the associations between SNPs rs7787082 (ABCB1, OR = 0.2; 95% CI = 0.06-0.66, p = 0.008), rs12505410 (ABCG2, OR = 3.82; 95% CI = 1.38-10.55; p = 0.010), and rs3114018 (ABCG2, OR = 0.24; 95% CI = 0.08-0.71; p = 0.010) and the probability of achieving CCyR. Furthermore, progression-free survival (PFS) was significantly influenced by SNPs rs3732357 (HR = 0.2, 95% CI = 0.26-0.70; p = 0.001), rs3732360 (HR = 0.59; 95% CI = 0.38-0.93; p = 0.020), rs11917714 (HR = 0.58; 95% CI = 0.36-0.92; p = 0.020), and rs3732359 (HR = 0.57; 95% CI = 0.36-0.91; p = 0.024) in PXR; rs2307418 (HR = 2.02; 95% CI = 1.19-3.43; p = 0.048) in CAR; and rs2235023 (HR = 2.49; 95% CI = 1.13-5.50; p = 0.011) and rs22114102 (HR = 1.90; 95% CI = 1.00-3.63; p = 0.028) in ABCB1. Moreover, overall survival (OS) was impacted by rs3842 (HR = 1.84; 95% CI = 1.01-3.33; p = 0.012) and rs2235023 (HR = 2.28; 95% CI = 1.03 = 5.02; p = 0.027) in ABCB1, rs11265571 (HR = 1.59; 95% CI = 0.82-3.08; p = 0.037) and rs2307418 (HR = 73.68; 95% CI = 4.47-1215.31; p = 0.003) in CAR, and rs3732360 (HR = 0.64; 95% CI = 0.40 = 1.04; p = 0.049) in PXR. Taking into account the influence of the tested SNPs on treatment toxicity, we found a significant relationship between allele G of polymorphism in the ABCB1 rs7787082 (OR = 4.46; 95% CI = 1.38-14.39 p = 0.012) and hematological complications assuming the codominant gene inheritance model as well as a significant correlation between the presence of minor allele (G) of SNP rs2725256 in the ABCG2 gene (OR = 4.71; 95% CI = 1.20-18.47; p = 0.026) and the occurrence of non-hematological complications assuming a recessive gene inheritance model. Conclusion: Our data suggest that inherited variants in the genes encoding for proteins involved in the transport of xenobiotics may modify the toxicity and efficacy of dasatinib therapy in CML patients.

A randomized phase III study of carfilzomib vs low-dose corticosteroids with optional cyclophosphamide in relapsed and refractory multiple myeloma (FOCUS).

This randomized, phase III, open-label, multicenter study compared carfilzomib monotherapy against low-dose corticosteroids and optional cyclophosphamide in relapsed and refractory multiple myeloma (RRMM). Relapsed and refractory multiple myeloma patients were randomized (1:1) to receive carfilzomib (10-min intravenous infusion; 20 mg/m2 on days 1 and 2 of cycle 1; 27 mg/m2 thereafter) or a control regimen of low-dose corticosteroids (84 mg of dexamethasone or equivalent corticosteroid) with optional cyclophosphamide (1400 mg) for 28-day cycles. The primary endpoint was overall survival (OS). Three-hundred and fifteen patients were randomized to carfilzomib (n=157) or control (n=158). Both groups had a median of five prior regimens. In the control group, 95% of patients received cyclophosphamide. Median OS was 10.2 (95% confidence interval (CI) 8.4-14.4) vs 10.0 months (95% CI 7.7-12.0) with carfilzomib vs control (hazard ratio=0.975; 95% CI 0.760-1.249; P=0.4172). Progression-free survival was similar between groups; overall response rate was higher with carfilzomib (19.1 vs 11.4%). The most common grade ⩾3 adverse events were anemia (25.5 vs 30.7%), thrombocytopenia (24.2 vs 22.2%) and neutropenia (7.6 vs 12.4%) with carfilzomib vs control. Median OS for single-agent carfilzomib was similar to that for an active doublet control regimen in heavily pretreated RRMM patients.

Imatinib-associated neutropenia may not be overcome by filgrastim treatment in patients with blastic phase of chronic myeloid leukaemia.

Imatinib mesylate is a very effective treatment in patients with Philadelphia (Ph)-positive chronic myeloid leukaemia (CML). However, in patients with advanced phase CML, it is still unclear whether, in the presence of myelosuppression, therapy with imatinib should be continued. It has been reported that intermittent filgrastim treatment may overcome imatinib-associated neutropenia and allow improved delivery of imatinib. Such combined sequential treatment is theoretically attractive as it may lead to better disease response. Here, we report a patient with blastic phase CML who developed severe and prolonged myelosuppression during imatinib treatment. Despite cessation of imatinib and 2 months of filgrastim therapy neither recurrence of Ph-positive or Ph-negative cells occurred. We conclude that filgrastim treatment may not always reverse imatinib-associated neutropenia therefore the decision of continued imatinib therapy in patients with advanced CML should be taken with caution.

Second malignancies and Richter's syndrome in patients with chronic lymphocytic leukaemia treated with cladribine.

The increased frequency of second malignancies in chronic lymphocytic leukaemia (CLL) is well known. Moreover, antineoplastic therapy additionally increases the risk of secondary cancers. In this study, we analysed whether treatment with cladribine (2-chlorodeoxyadenosine, 2-CdA) during the course of CLL had an impact on the subsequent occurrence of either secondary solid tumours or Richter's syndrome. There were 1487 eligible patients, 251 treated with 2-CdA alone, 913 treated with alkylating agents (AA)-based regimens alone and 323 treated with both 2-CdA and AA. Median time from the start of CLL treatment to the diagnosis of secondary malignancy was 1.9 years (0.5-5.1 years) for the 2-CdA group, 1.8 years (0.3-7.9 years) for the AA group and 3.9 years (0.3-8.4 years) for the 2-CdA+AA group. A total of 68 malignancies were reported in 65 patients. Ten events were non-melanotic skin cancers and were excluded from the analysis, leaving 58 events in 58 patients. In the group of patients treated with 2-CdA alone, there were 15 (6.0%) cases, in the group of patients treated with AA alone there were 26 (2.8%) cases, and in the group treated with 2-CdA+AA there were 17 (5.3%) cases of secondary malignancies. The differences between the frequency of secondary malignancies in the 2-CdA and 2-CdA+AA versus AA alone groups were not significant (P=0.05 and P=0.06, respectively). Only lung cancers occurred significantly more frequently in the 2-CdA (2.8%) and 2-CdA+AA (2.2%) treated groups compared with the AA patients (0.3%) (P<0.001 and P<0.01, respectively). In conclusion, 2-CdA in CLL patients does not seem to increase the risk of secondary malignancies except for lung cancers. However, further studies are necessary to establish the real risk of lung cancer in CLL patients treated with 2-CdA.

Cladribine combined with cyclophosphamide and mitoxantrone as front-line therapy in chronic lymphocytic leukemia.

The objective of the study was to determine the effectiveness and the toxicity of a combined chemotherapy consisting of cladribine (2-CdA), mitoxantrone and cyclophosphamide (CMC regimen) in the treatment of previously untreated B cell chronic lymphocytic leukemia (B-CLL). From August 1998 to December 2000 2-CdA was administered at a dosage of 0.12 mg/kg for 3 (CMC3) or 5 (CMC5) consecutive days, mitoxantrone at 10 mg/m2 on day 1 and cyclophosphamide at 650 mg/m2 on day 1 to 62 patients with advanced or progressive B-CLL. The cycles were repeated at 4 week intervals or longer if severe myelosuppression occurred. Twenty patients received CMC5 and 42 patients CMC3. Within the analyzed group an overall response (OR) rate (CR+PR) of 64.5% (95% CI: 52.7-76.3%) was reported, including 29.0% CR. There was no difference in the CR rate between the patients treated with CMC5 (30%) and CMC3 (28.6%) (P = 0.9), nor in the OR rate (55.0% and 69.0%, respectively, P = 0.3). Residual disease was identified in seven out of 18 (38.9%) patients who were in CR, including two treated with CMC5 and five treated with CMC3 protocols. CMC-induced grade III or IV thrombocytopenia occurred in 12 (19.4%) of patients, including four (20%) CMC5-treated and eight (19%) CMC3-treated patients (P= 0.8). Neutropenia grade III or IV was observed in seven (35%) and 11 (26.2%) patients, respectively (P = 0.8). Severe infections, including pneumonia and sepsis, occurred more frequently after CMC5 (11 patients, 55.0%) than CMC3 (10 patients, 28.6%) (P = 0.03) Fourteen patients died, including six treated with CMC5 and eight treated with CMC3 (30% and 19%, respectively). Infections were the cause of death in nine patients, including four in the CMC5 group and five in the CMC3 group. In conclusion, our results indicate that the CMC programme is an active combined regimen in previously untreated B-CLL patients; its efficiency seems to be similar to that observed earlier in B-CLL patients treated with 2-CdA as a single agent. However, toxicity, especially after CMC5 administration, is significant. Therefore, we recommend the CMC3 but not the CMC5 programme for further evaluation.

Immunogenicity of influenza vaccine in patients with hemato-oncological disorders.

The aim of this study was to measure the production of antihemagglutinin and antineuraminidase antibodies in patients with proliferative diseases of the hematopoietic or lymphatic system, immunized with influenza vaccine in the epidemic season 1995/96. Twenty patients between 22 and 84 years volunteered for vaccination and were vaccinated subcutaneously with a single dose of split trivalent influenza vaccine ("Fluarix", SmithKline Beecham) in autumn 1995 at the outpatients clinic, General Hospital, Torun, Poland, where they were being treated with anti-cancer chemotherapy. The vaccine consisted of a 0.5 ml dose containing 15 microg hemagglutinin (HA) of each of the following strains: A/Singapore/6/86 (H1N1), A/Johannesburg/33/94 (H3N2) and B/Beijing/184/93. Neuraminidase activity amounted to 17.24x10(-3) U/ml. Antibody production was determined in sera collected before vaccination, 10 days and 28 days after vaccination by the hemagglutinin inhibition test (HI) and neuraminidase inhibition test (NI). Mean fold increase values after vaccination were statistically significant in patients undergoing cytostatic treatment. After 28 days mean fold increase of antihemagglutinin antibodies ranged from 7.9 to 25.2, while in the case of antineuraminidase antibodies these values were between 12.4 and 14.3. It is notable that no adverse reactions were observed after immunization and none of the patients was infected with influenza virus, in spite of the fact that there was a local epidemic in the Torun region when the study was carried out. The results presented in this paper confirm the beneficial effect of influenza vaccination in high-risk groups of patients with proliferative diseases of the hematopoietic and lymphatic systems.