Agneta Swedin

Fusion of the BCR and the fibroblast growth factor receptor-1 (FGFR1) genes as a result of t(8;22)(p11;q11) in a myeloproliferative disorder: The first fusion gene involving BCR but not ABL

Constitutive activation of tyrosine kinases as a consequence of chromosomal translocations, forming fusion genes, plays an important role in the development of hematologic malignancies, in particular, myeloproliferative syndromes (MPSs). In this respect, the t(9;22)(q34;q11) that results in the BCR/ABL fusion gene in chronic myeloid leukemia is one of the best‐studied examples. The fibroblast growth factor receptor 1 (FGFR1) gene at 8p11 encodes a transmembrane receptor tyrosine kinase and is similarly activated by chromosomal translocations, in which three alternative genes—ZNF198 at 13q12, CEP110 at 9q34, and FOP at 6q27—become fused to the tyrosine kinase domain of FGFR1. These 8p11‐translocations are associated with characteristic morphologic and clinical features, referred to as “8p11 MPS.” In this study, we report the isolation and characterization of a novel fusion gene in a hematologic malignancy with a t(8;22)(p11;q11) and features suggestive of 8p11 MPS. We show that the breakpoints in the t(8;22) occur within introns 4 and 8 of the BCR and FGFR1 genes, respectively. On the mRNA level, the t(8;22) results in the fusion of BCR exons 1–4 in‐frame with the tyrosine kinase domain of FGFR1 as well as in the expression of a reciprocal FGFR1/BCR chimeric transcript. By analogy with data obtained from previously characterized fusion genes involving FGFR1 and BCR/ABL, it is likely that the oligomerization domain contributed by BCR is critical and that its dimerizing properties lead to aberrant FGFR1 signaling and neoplastic transformation.

Fusion gene-mediated truncation of RUNX1 as a potential mechanism underlying disease progression in the 8p11 myeloproliferative syndrome.

The 8p11 myeloproliferative syndrome (EMS) is a chronic myeloproliferative disorder molecularly characterized by fusion of various 5′ partner genes to the 3′ part of the fibroblast growth factor receptor 1 (FGFR1) gene at 8p, resulting in constitutive activation of the tyrosine kinase activity contained within FGFR1. EMS is associated with a high risk of transformation to acute myeloid leukemia (AML), but the mechanisms underlying the disease progression are unknown. In the present study, we have investigated a case of EMS harboring a t(8;22)(p11;q11)/BCR‐FGFR1 rearrangement as well as a t(9;21)(q34;q22) at the time of AML transformation. FISH and RT‐PCR analyses revealed that the t(9;21) leads to a fusion gene consisting of the 5′ part of RUNX1 (exons 1–4) fused to repetitive sequences of a gene with unknown function on chromosome 9, adding 70 amino acids to RUNX1 exon 4. The t(9;21) hence results in a truncation of RUNX1. No point mutations were found in the other RUNX1 allele. The most likely functional outcome of the rearrangement was haploinsufficiency of RUNX1, which thus may be one mechanism by which EMS transforms to AML.

Thalidomide and dexamethasone vs. bortezomib and dexamethasone for melphalan refractory myeloma: a randomized study

Objectives:  Thalidomide and bortezomib have been frequently used for second‐line therapy in patients with myeloma relapsing after or refractory to initial melphalan‐based treatment, but no randomized trials have been published comparing these two treatment alternatives.

Improved survival in myeloma patients: starting to close in on the gap between elderly patients and a matched normal population

The outcome for multiple myeloma patients has improved since the introduction of bortezomib, thalidomide and lenalidomide. However, studies comparing new and conventional treatment include selected patient groups. We investigated consecutive patients (n = 1638) diagnosed in a defined period and compared survival with a gender‐ and age‐matched cohort Swedish population (n = 9 340 682). Median overall survival for non‐high‐dose treated patients was 2·8 years. The use of bortezomib, thalidomide or lenalidomide in first line therapy predicted a significantly longer overall survival (median 4·9 years) compared to conventional treatment (2·3 years). Among non‐high‐dose treated patients receiving at least 2 lines with bortezomib, thalidomide or lenalidomide, 69% and 63% have survived at 3 and 5 years as compared to 48% and 22% with conventional drugs and 88% and 79% in the matched cohort populations, respectively. The median overall survival in high‐dose treated patients was 6·9 years. Of these patients, 84% survived at 3 years and 70% at 5 years as compared to 98% and 95% in the matched cohort population. Overall survival in the best non‐high‐dose treated outcome group is closing the gap with the matched cohort. Upfront use of new drugs is clearly better than waiting until later lines of treatment.

Thalidomide and dexamethasone vs. bortezomib and dexamethasone for melphalan refractory myeloma

Objectives:  Thalidomide and bortezomib have been frequently used for second‐line therapy in patients with myeloma relapsing after or refractory to initial melphalan‐based treatment, but no randomized trials have been published comparing these two treatment alternatives.

Clinical utility of immunoglobulin heavy chain gene rearrangement identification for tumour cell detection in multiple myeloma

In an attempt to define the clinical utility of immunoglobulin heavy chain (IgH) gene rearrangement identification for tumour cell detection in multiple myeloma, we investigated 36 consecutive newly diagnosed patients intended for high‐dose chemotherapy in a study protocol. After identification of the IgH rearrangement, an allele specific oligonucleotide (ASO) was constructed and used in a semiquantative PCR for minimal residual disease (MRD) evaluation. The myeloma‐specific IgH gene rearrangement could be identified and an ASO primer constructed in 24 (67%) of the patients. All of these patients underwent transplantation; 22 were autologous, of whom three had PCR‐negative stem cell harvests, and two were allogeneic. 10 patients achieved a clinical complete response (CR) and five were PCR negative in sequential bone marrow analyses. In patients not achieving CR, PCR negativity was occasionally found, but in general the PCR results reflected the clinical status of the patients. No consistent relationship between the bone marrow MRD status and the clinical course was found, and early relapses occurred also in PCR‐negative patients.

Pharmacogenetic study of the impact of ABCB1 single-nucleotide polymorphisms on lenalidomide treatment outcomes in patients with multiple myeloma: results from a phase IV observational study and subsequent phase II clinical trial

PurposeDespite therapeutic advances, patients with multiple myeloma (MM) continue to experience disease relapse and treatment resistance. The gene ABCB1 encodes the drug transporter P-glycoprotein, which confers resistance through drug extrusion across the cell membrane. Lenalidomide (Len) is excreted mainly via the kidneys, and, given the expression of P-gp in the renal tubuli, single-nucleotide polymorphisms (SNPs) in the ABCB1 gene may influence Len plasma concentrations and, subsequently, the outcome of treatment. We, therefore, investigated the influence of ABCB1 genetic variants on Len treatment outcomes and adverse events (AEs).MethodsNinety patients with relapsed or refractory MM, who received the second-line Len plus dexamethasone in the Rev II trial, were genotyped for the ABCB1 SNPs 1199G>A (Ser400Asn, rs2229109), 1236C>T (silent, rs1128503), 2677G>T/A (Ala893Ser, rs2032582), and 3435C>T (silent, rs1045642) using pyrosequencing, and correlations to response parameters, outcomes, and AEs were investigated.ResultsNo significant associations were found between genotype and either best response rates or hematological AEs, and 1236C>T, 2677G>T or 3435C>T genotypes had no impact on survival. There was a trend towards increased time to progression (TTP) in patients carrying the 1199A variant, and a significant difference in TTP between genotypes in patients with standard-risk cytogenetics.ConclusionsOur findings show a limited influence of ABCB1 genotype on lenalidomide treatment efficacy and safety. The results suggest that 1199G>A may be a marker of TTP following Len treatment in standard-risk patients; however, larger studies are needed to validate and clarify the relationship.

Lenalidomide versus lenalidomide + dexamethasone prolonged treatment after second-line lenalidomide + dexamethasone induction in multiple myeloma

Lenalidomide (Len) plus dexamethasone (Dex) is approved for the treatment of relapsed or refractory multiple myeloma (RRMM). It is possible that single‐agent Len may be effective as prolonged treatment regimen in RRMM once patients demonstrate an initial response to Len+Dex induction. Patients with RRMM who responded to first‐line Len+Dex in an observational study (NCT01430546) received up to 24 cycles of either Len (25 mg/day) or Len+Dex (25 mg/day and 40 mg/week) as prolonged treatment in a subsequent phase 2 clinical trial (NCT01450215). In the observational study (N = 133), median time to response was 1.7 (range 0.6–9.6) months. A complete response to all treatments received in both studies was observed in 11% of patients; very good partial response and partial response rates were 31% and 38%, respectively. Corresponding response rates in the subgroup of patients who did not enter the phase 2 trial (n = 71) were 3%, 18%, and 39%, respectively. Rates of disease progression at 2 years in the phase 2 trial were 47% versus 31% for Len versus Len+Dex (P = 0.14). After 36 months median follow‐up in surviving patients, median time to progression was not reached with Len+Dex and was 24.9 months (95% confidence interval 12.5–not calculable, P < 0.001) with Len. Three‐year OS among the total observational study population was 61% (95% CI, 52–69%). The corresponding rate among patients who entered the phase 2 clinical trial was 73% (95% CI, 60–83%) and was significantly lower among those patients who achieved ≥PR but did not proceed into the phase 2 trial (55%; P = 0.01). In the phase 2 trial, OS was 73% in both treatment arms (P = 0.70). Neutropenia and thrombocytopenia were more common with prolonged (phase 2 trial) versus short‐term (observational study) Len administration but remained manageable. Prolonged treatment with Len with or without Dex provides sustained, clinically relevant responses and demonstrates an acceptable safety profile.

Abstract 5030: The impact ofABCB1single nucleotide polymorphisms on the outcome in lenalidomide treated multiple myeloma patients

Introduction: Multiple myeloma (MM) is an incurable plasma cell malignancy with high mortality rate. Treatment outcomes have improved since the introduction of new drugs such as the IMiD lenalidomide, but relapse rates and resistance is still a problem. The gene ABCB1 encodes the drug transporter p-glycoprotein (p-gp) which confers resistance through extrusion of drugs over the cell membrane. Lenalidomide is subject to limited metabolism and excreted mainly via the kidneys. In vitro studies have shown lenalidomide to be an ABCB1 substrate, and single nucleotide polymorphisms (SNPs) affecting gene expression, transporter function and/or activity may affect drug distribution and the subsequent outcome and risk of adverse events. However, in vivo studies of the effect of ABCB1 on lenalidomide pharmacokinetics are contradictory. Our aim was to investigate the influence of ABCB1 SNPs on lenalidomide treatment outcome and adverse events (AE). Materials & Methods: In the observational part of two connected studies, 133 Lenalidomide naive patients at 1st relapse/refractory MM were treated with lenalidomide and dexamethasone for up to 9 cycles of 4 weeks. In the prospective 2nd part, 62 patients that had achieved at least partial response according to IMWG-criteria followed by at least two additional treatment cycles were randomized to either lenalidomide/dexamethasone or lenalidomide as a single drug. 90 patients (of which 47 was further randomized to the 2nd part) had samples available for genotyping of the ABCB1 SNPs 1199G>A (Ser400Asn, rs2229109), 1236C>T (rs1128503), 2677G>T/A (Ala893Ser, rs2032582) and 3435C>T (rs1045642) using Pyrosequencing. Correlations to overall survival, time to progression (TTP), response parameters and AE were investigated, and a p-value of 0.05 was considered significant. Results: No significant correlations to hematological AE or response rates were found, and no impact on survival for 1236C>T, 2677G>T/A or 3435C>T, neither in the whole population nor in patients randomized to the 2nd part. The results were similar also when risk (according to FISH) was considered. There was a trend towards improved TTP for patients carrying the 1199A variant; mean TTP 3.2 years (95%CI 2.3-4.1) vs 2.2 years (95%CI 1.8-2.6) for G/A and G/G, respectively (p=0.076). This trend was confirmed in the multivariable cox regression analysis; HR=0.280 (95%CI 0.74-1.054), p=0.06. The difference in TTP was significant in the non-high risk subgroup; mean TTP 4.3 years (95%CI 3.7-4.9) vs 2.3 years (95%CI 1.8-2.8), p=0.034, for G/A and G/G, respectively. Conclusion: No evidence was found for a large impact of 1236C>T, 2677G>T/A or 3435C>T on lenalidomide treatment outcome or risk of hematological AE. 1199G>A may be a potential marker of TTP in non-high risk MM but further studies in a larger cohort is needed to clarify the relationship and whether this is due to altered drug transport or efflux independent mechanisms. Citation Format: Ingrid Jakobsen Falk, Johan Lund, Henrik Green, Astrid Gruber, Evren Alici, Birgitta Lauri, Cecilie Blimark, Ulf-Henrik Mellqvist, Agneta Swedin, Karin Forsberg, Conny Carlsson, Mats Hardling, Lucia Ahlberg, Hareth Nahi, Kourosh Lotfi. The impact of ABCB1 single nucleotide polymorphisms on the outcome in lenalidomide treated multiple myeloma patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5030. doi:10.1158/1538-7445.AM2017-5030