How to Simplify the Evaluation of Newly Introduced Chemotherapeutic Interventions in Myeloma.

When the bortezomib [PS341], adriamycin and dexamethasone (PAD) regimen was first evaluated, the response rate in untreated patients was much superior to that elicited by conventional chemotherapeutic agents. We demonstrated the efficacy of PAD in relapsed or refractory patients by comparing the response rate obtained in 53 patients who received vincristine, adriamycin and dexamethasone (VAD) or equivalent regimen as induction therapy, using a comparative design in which each patient acted as their own control. Whereas 25 patients had a positive response to VAD, 37 patients had a response to PAD ≤ partial remission (PR) (p = 0.023). Using the more stringent response level of very good PR (VGPR) the results favored the PAD regimen very significantly (p = 0.006) (McNemars test). Similar results were seen using paired M-protein levels from individual patient comparisons. As the PAD regimen was subsequently adopted as the re-induction therapy in the British Society for Blood and Marrow Transplantation/United Kingdom Myeloma Forum Myeloma X (Intensive) trial, now concluded, we have retrospectively analyzed the findings from both studies. Comparison of response rates and adverse effects of patients having had previous autologous transplantation (Cohort 1) with the corresponding data from Myeloma X showed close correlation. These findings provide evidence that rapid results may be obtained in the evaluation of newly introduced, and potentially highly effective, anti-tumour agents by direct comparison to the response to the immediately preceding standard regimen, particularly in relatively resistant tumours.

Neither P-gp SNP variants, P-gp expression nor functional P-gp activity predicts MDR in a preliminary study of plasma cell myeloma.

INTRODUCTION: Multidrug resistance (MDR) mediated by P-glycoprotein (P-gp) can compromise the successful treatment of many malignancies including plasma cell myeloma (PCM). However, methods do not yet exist that can accurately determine P-gp activity in PCM patient samples. METHODS: In this study, we have utilized new advances in flow cytometric methods to determine the activity of P-gp in PCM tumor cells. Furthermore, we have used several PCR-based approaches to perform a pilot study determining the functional impact of ABCB1 SNPs in patients with PCM. RESULTS: No associations were seen between P-gp activity or expression and subgroups of PCM. Similarly, no association was seen between P-gp expression and SNPs within ABCB1 although a nonsignificant reduction in activity was demonstrated for rs1045642 (P = 0.121). CONCLUSIONS: We have described a new method for the determination of P-gp and MRP activity suitable for use in clinical studies and have optimized this method to include a gating strategy, allowing routine use on PCM bone marrow aspirate samples. This is the first patient study to consider the full impact of SNPs within ABCB1 all the way from the genome to the proteome in PCM. The methods described here could also be utilized for future studies of "stem cell like" side populations in PCM that are considered to be drug resistant. Furthermore, minor amendments to these methods will facilitate studies of P-gp, MRP, and BCRP activity in other haematological malignancies.

ABCB1 (MDR1) rs1045642 is associated with increased overall survival in plasma cell myeloma.

Multi-drug resistance (MDR) may compromise the successful management of haematological malignancies, impairing the effectiveness of chemotherapy. The P-glycoprotein (P-gp) drug efflux pump, encoded by the gene ABCB1 (MDR1), is the most widely studied component in MDR. A single nucleotide polymorphism (SNP) has been identified within ABCB1, rs1045642 (C3435T), which may alter P-gp substrate specificity and have an impact on the effectiveness of treatment, and hence overall survival (OS). We estimated the frequency of this SNP in the Northern Irish population and investigated its impact on the OS of patients with plasma cell myeloma (PCM). There was no significant difference in the frequency of rs1045642 between the PCM cohort and an age- and gender-matched control population. Findings within the PCM cohort suggest that rs1045642 genotype influences OS (p = 2 x 10(-2)). If confirmed in larger studies, these results suggest that genotyping rs1045642 may be a useful predictor of outcome in PCM and could indicate modified treatment modalities in certain individuals.

Serum TK levels in CLL identify Binet stage A patients within biologically defined prognostic subgroups most likely to undergo disease progression.

OBJECTIVE: Serum thymidine kinase (TK) levels have been shown to be correlated with survival in many malignancies, including chronic lymphocytic leukaemia (CLL). This study was designed to investigate associations between TK levels and other prognostic markers, in newly and previously diagnosed Binet stage A patients. Furthermore, the use of serum TK measurement to identify subcategories of disease within those defined by IgV(H) mutational status, gene usage and chromosomal aberrations was investigated. METHODS: Ninety-one CLL patients were enrolled. Serum TK levels were measured using a radioenzyme assay. IgV(H) mutational status and V(H) gene usage were determined using BIOMED-2 primers and protocol. Recurring chromosomal abnormalities were detected by interphase fluorescent in situ hybridisation (FISH). Flow cytometry and reverse transcriptase polymerase chain reaction (RT-PCR) determined CD38 and Zap-70 expression, respectively. RESULTS: Significantly higher serum TK levels were found in IgV(H) unmutated, compared with IgV(H) mutated, patients (P < 0.001). Elevated TK levels were also found in patients with CD38 and Zap-70 positivity (P = 0.004, P < 0.001, respectively), short lymphocyte doubling time (LDT) (P = 0.044) and poor or intermediate prognosis chromosomal aberrations (P < 0.001). CONCLUSION: A TK level of >8.5 U/L best identified patients with progressive disease. Elevated TK levels could identify patients categorised, at diagnosis, into good prognosis subgroups by the various biological markers (mutated IgV(H), good prognosis chromosomal aberrations, Zap-70(-) and CD38(-)) who subsequently showed disease progression. Additionally, patients with V(H)3-21 gene usage showed high TK levels, irrespective of mutational status, and serum TK measurement retained predictive power as disease progressed in all subcategories studied.

Tetrasomy 13 as the sole cytogenetic abnormality in acute myeloid leukemia M1 without maturation.

We report a case of acute myeloid leukemia (AML) M1 showing a 48,XY,+13,+13 karyotype. Treatment was according to the Medical Research Council AML14 trial protocol with two courses of DAT chemotherapy. Postchemotherapy bone marrow examination failed to show complete remission or cytogenetic normalization. Despite having resistant disease, the patient initially remained clinically well although requiring regular blood transfusions for anemia. However his leukocyte count gradually increased and he became symptomatic. He was treated subsequently with FLAG but died approximately 2 weeks later, 6 months after first presenting. Tetrasomy 13 as the sole cytogenetic abnormality has not been reported previously in M1 AML and has only been reported in three other AML cases, all with an immature phenotype and poor outcome.