The impact of intra-clonal heterogeneity on the treatment of multiple myeloma

Towards Stratified Medicine in Plasma Cell Myeloma

Plasma cell myeloma is a clinically heterogeneous malignancy accounting for approximately one to 2% of newly diagnosed cases of cancer worldwide. Treatment options, in addition to long-established cytotoxic drugs, include autologous stem cell transplant, immune modulators, proteasome inhibitors and monoclonal antibodies, plus further targeted therapies currently in clinical trials. Whilst treatment decisions are mostly based on a patient’s age, fitness, including the presence of co-morbidities, and tumour burden, significant scope exists for better risk stratification, sub-classification of disease, and predictors of response to specific therapies. Clinical staging, recurring acquired cytogenetic aberrations, and serum biomarkers such as β-2 microglobulin, and free light chains are in widespread use but often fail to predict the disease progression or inform treatment decision making. Recent scientific advances have provided considerable insight into the biology of myeloma. For example, gene expression profiling is already making a contribution to enhanced understanding of the biology of the disease whilst Next Generation Sequencing has revealed great genomic complexity and heterogeneity. Pathways involved in the oncogenesis, proliferation of the tumour and its resistance to apoptosis are being unravelled. Furthermore, knowledge of the tumour cell surface and its interactions with bystander cells and the bone marrow stroma enhance this understanding and provide novel targets for cell and antibody-based therapies. This review will discuss the development in understanding of the biology of the tumour cell and its environment in the bone marrow, the implementation of new therapeutic options contributing to significantly improved outcomes, and the progression towards more personalised medicine in this disorder.

The possible role of burden of therapy on the risk of myeloma extramedullary spread

Extramedullary relapse (EMR) represents a poor prognostic marker in the course of multiple myeloma (MM). We reviewed data from 329 patients, diagnosed between 2000 and 2010, without extramedullary disease at onset to explore possible risk factors for EMR. The median overall survival of our study cohort was 6.4 years. The risk of EMR was 28 % with a median time from diagnosis to first EMR of 2.2 years (0.2-9.1 years). Patients with soft tissue masses located in extra-osseous organs (EMR-S) showed the worst outcome, compared to those with tumor masses arising from adjacent bone (EMR-B) (median OS 1.6 vs 2.4 years, p = 0.006). In addition, patients with EMR-S showed a significant trend for further development of extramedullary masses in a very short time (3.7 vs 5.7 months for EMR-B, p = 0.043). Multivariate analysis failed to identify any clinically presenting features predictive for EMR. The occurrence of EMR was higher in patients with more complex treatment history, defined on the basis of longer treatment duration (≥6 vs <6 months) and on elevated number of treatment lines administered (>2 vs ≤2 lines) (HR = 4.5, p < 0.001 and HR = 9.0, p < 0.001, respectively, when one or both factors are present).In conclusion, increasing burden of treatment might be a possible risk factor for EMR. MM patients with multiple relapses should be comprehensively investigated including, when possible, a whole-body-targeted radiologic technique to accurately detect EMR. Treatment choice should take into account the very poor outcome for patients with soft tissue involvement.

Advances in understanding prognosis in myeloma

In the last two decades outcomes in multiple myeloma (myeloma) have greatly improved, due to the introduction of newer, more effective therapies. This improvement is not uniform. Response to treatment and survival remains heterogeneous, with some patients living for 1-2 years whilst others are alive and progression-free at 10 years. This variation in outcome is due to patient characteristics plus features intrinsic to the myeloma tumour. Alongside the introduction of novel therapies there has been a greater understanding of disease biology and mechanisms of resistance. This has led to an increase in the number of prognostic markers that can be used in myeloma. This is important not only for more accurate counselling of patients in terms of disease outcome, but also in paving the way for risk-adapted therapy. Both newer and traditional prognostic markers need to be used in the context of planned therapy. Indeed, the prognostic value of certain markers varies according to which therapy the patient receives. As such, these prognostic factors will require constant re-evaluation as agents with new mechanisms of action are added into the myeloma treatment algorithm. This article summarises current concepts of prognostic markers in myeloma.

CD38 expression and complement inhibitors affect response and resistance to daratumumab therapy in myeloma

Response to the CD38-targeting antibody daratumumab is significantly associated with CD38 expression levels on the tumor cells. Resistance to daratumumab is accompanied by increased expression of complement-inhibitory proteins.

Together for better?

In this issue of Blood, Mateos et al report that bortezomib plus melphalan and prednisone (VMP) and lenalidomide plus low-dose dexamethasone (Rd) administered in a sequential or an alternating scheme were equally active and induced comparable toxicities in elderly myeloma patients.

11C-Methionine-PET: a novel and sensitive tool for monitoring of early response to treatment in multiple myeloma

Multiple myeloma (MM) remains an essentially incurable hematologic malignancy. However, new treatment modalities and novel drugs have been introduced and thus additional tools for therapy monitoring are increasingly needed. Therefore, we evaluated the radiotracers 11C-Methionine (paraprotein-biosynthesis) and 18F-FDG (glucose-utilization) for monitoring response to anti-myeloma-therapy and outcome prediction. Influence of proteasome-inhibition on radiotracer-uptake of different MM cell-lines and patient-derived CD138+ plasma cells was analyzed and related to tumor-biology. Mice xenotransplanted with MM.1S tumors underwent MET- and FDG-μPET. Tumor-to-background ratios before and after 24 h, 8 and 15 days treatment with bortezomib were correlated to survival. Treatment reduced both MET and FDG uptake; changes in tracer-retention correlated with a switch from high to low CD138-expression. In xenotransplanted mice, MET-uptake significantly decreased by 30-79% as early as 24 h after bortezomib injection. No significant differences were detected thus early with FDG. This finding was confirmed in patient-derived MM cells. Importantly, early reduction of MET- but not FDG-uptake correlated with improved survival and reduced tumor burden in mice. Our results suggest that MET is superior to FDG in very early assessment of response to anti-myeloma-therapy. Early changes in MET-uptake have predictive potential regarding response and survival. MET-PET holds promise to individualize therapies in MM in future.

Tumor Stroma, Tumor Blood Vessels, and Antiangiogenesis Therapy

Solid tumors generally require a vascularized connective tissue stroma if they are to grow beyond minimal size. They generate that stroma in part by secreting vascular endothelial growth factor (VEGF), a potent vascular permeability and angiogenic factor. Increased vascular permeability leads to deposition of a provisional fibrin stroma, which supports tumor, connective tissue, and inflammatory cell migration and plays an active role in the formation of mature vascularized stroma. Vascular endothelial growth factor-induced tumor blood vessels are heterogeneous, of at least 6 distinct types, and develop linearly over time. They include both angiogenic (mother vessels, glomeruloid microvascular proliferations, vascular malformations, capillaries) and arteriovenogenic (feeding arteries, draining veins) blood vessels. Attacking the tumor vasculature with drugs that target VEGF or its receptors (VEGFR) has come into vogue but has been less effective than had been hope for. One reason for this is that anti-VEGF/VEGFR therapy attacks only a subset of tumor blood vessels, the earliest to form. New targets on late-forming blood vessels such as feeding arteries would be useful in helping antivascular cancer therapy fulfill its promise.

Opposite activation of the Hedgehog pathway in CD138+ plasma cells and CD138-CD19+ B cells identifies two subgroups of patients with multiple myeloma and different prognosis

Hyperactivation of the Hedgehog (Hh) pathway, which controls refueling of multiple myeloma (MM) clones, might be critical to disease recurrence. Although several studies suggest the Hh pathway is activated in CD138- immature cells, differentiated CD138+ plasma cells might also be able to self-renew by producing themselves the Hh ligands. We studied the gene expression profiles of 126 newly diagnosed MM patients analyzed in both the CD138+ plasma cell fraction and CD138-CD19+ B-cell compartment. Results demonstrated that an Hh-gene signature was able to cluster patients in two subgroups characterized by the opposite Hh pathway expression in mature plasma cells and their precursors. Strikingly, patients characterized by Hh hyperactivation in plasma cells, but not in their B cells, displayed high genomic instability and an unfavorable outcome in terms of shorter progression-free survival (hazard ratio: 1.92; 95% confidence interval: 1.19-3.07) and overall survival (hazard ratio: 2.61; 95% confidence interval: 1.26-5.38). These results suggest that the mechanisms triggered by the Hh pathway ultimately led to identify a more indolent vs a more aggressive biological and clinical subtype of MM. Therefore, patient stratification according to their molecular background might help the fine-tuning of future clinical and therapeutic studies.

Myeloma Is Not a Single Disease

Treatment of plasma cell disorders has dramatically improved during the past decade as a result of the availability of new biology-based drugs, such as proteasome inhibitors and immunomodulatory agents. With increased attention to disease biology, however, it has become clear that there are many different subsets of patients with myeloma with different biologic drivers as well as different patient-based characteristics that can influence treatment. Obtaining initial genetics or genomics information can provide some of the information needed to define therapy after initial induction, and careful performance status assessment can help to define patient-specific characteristics that are important when determining the intensity of therapy. Careful assessment of both can help to optimize therapy type and duration for all patients and to improve long-term outcomes.

Panel sequencing for clinically oriented variant screening and copy number detection in 142 untreated multiple myeloma patients

We employed a customized Multiple Myeloma (MM)-specific Mutation Panel (M³P) to screen a homogenous cohort of 142 untreated MM patients for relevant mutations in a selection of disease-specific genes. M³Pv2.0 includes 77 genes selected for being either actionable targets, potentially related to drug–response or part of known key pathways in MM biology. We identified mutations in potentially actionable genes in 49% of patients and provided prognostic evidence of STAT3 mutations. This panel may serve as a practical alternative to more comprehensive sequencing approaches, providing genomic information in a timely and cost-effective manner, thus allowing clinically oriented variant screening in MM.

Engineering Multi-Walled Carbon Nanotube Therapeutic Bionanofluids to Selectively Target Papillary Thyroid Cancer Cells

BACKGROUND

The incidence of papillary thyroid carcinoma (PTC) has risen steadily over the past few decades as well as the recurrence rates. It has been proposed that targeted ablative physical therapy could be a therapeutic modality in thyroid cancer. Targeted bio-affinity functionalized multi-walled carbon nanotubes (BioNanofluid) act locally, to efficiently convert external light energy to heat thereby specifically killing cancer cells. This may represent a promising new cancer therapeutic modality, advancing beyond conventional laser ablation and other nanoparticle approaches.

METHODS

Thyroid Stimulating Hormone Receptor (TSHR) was selected as a target for PTC cells, due to its wide expression. Either TSHR antibodies or Thyrogen or purified TSH (Thyrotropin) were chemically conjugated to our functionalized Bionanofluid. A diode laser system (532 nm) was used to illuminate a PTC cell line for set exposure times. Cell death was assessed using Trypan Blue staining.

RESULTS

TSHR-targeted BioNanofluids were capable of selectively ablating BCPAP, a TSHR-positive PTC cell line, while not TSHR-null NSC-34 cells. We determined that a 2:1 BCPAP cell:α-TSHR-BioNanofluid conjugate ratio and a 30 second laser exposure killed approximately 60% of the BCPAP cells, while 65% and >70% of cells were ablated using Thyrotropin- and Thyrogen-BioNanofluid conjugates, respectively. Furthermore, minimal non-targeted killing was observed using selective controls.

CONCLUSION

A BioNanofluid platform offering a potential therapeutic path for papillary thyroid cancer has been investigated, with our in vitro results suggesting the development of a potent and rapid method of selective cancer cell killing. Therefore, BioNanofluid treatment emphasizes the need for new technology to treat patients with local recurrence and metastatic disease who are currently undergoing either re-operative neck explorations, repeated administration of radioactive iodine and as a last resort external beam radiation or chemotherapy, with fewer side effects and improved quality of life.

Is it possible to cure myeloma without allogeneic transplantation?

During the last decades, a better understanding of the biology of multiple myeloma (MM) has led to the application of novel treatment strategies for MM patients. The new anti-myeloma regimens produce higher incidence of durable and of better quality responses and they improve overall survival, challenging the dogma of incurable disease, outside the context of allogeneic transplantation. This review presents all these strategies that aim to cure MM, including continuous treatment i.e. induction, consolidation and maintenance, treatment of asymptomatic MM and monitoring minimal residual disease using modern techniques, such as multi-parameter flow cytometry, molecular assays and advanced imaging.

Light Chain Escape in 3 Cases: Evidence of Intraclonal Heterogeneity in Multiple Myeloma from a Single Institution in Poland

We report three cases of light chain escape (LCE) at a single institution in Poland, including an interesting case of biclonal monoclonal gammopathy of undetermined significance (MGUS) that satisfied the criteria for progression to light chain multiple myeloma (LCMM) with a rapid rise in serum free light chain (FLC) levels, following steroidal treatment for simultaneous temporal artery inflammation and polymyalgia rheumatica (PMR). In the three cases discussed, progression of the disease by light chain escape was associated with rapid and severe renal impairment, highlighting the necessity for prompt detection of such free light chain-only producing clones in order to prevent the possible development of irreversible end-organ damage. Interestingly, monitoring of these three patients by serum free light chain assay (sFLC) and retrospective heavy/light chain analysis (HLC) detected this clonal evolution prior to clinical relapse and suggests that these assays represent important additional tools for more accurate monitoring of multiple myeloma patients.

Centrosome amplification and clonal evolution in multiple myeloma: Short review

Multiple myeloma (MM) is composed of an array of multiple clones, each potentially associated with different clinical behavior. Previous studies focused on clinical implication of centrosome amplification (CA) in MM show contradictory results. It seems that the role of CA as well as CA formation in MM differ from other malignancies. This has brought about a question about the role of CA positive clone which is--is it going to be a more aggressive clone evolutionally arising under pressure of negative conditions or can CA serve as a marker of cell abnormality and lead to cell death and further elimination of this damaged subpopulation? This current review is devoted to the discussion of the existence of MM subclones with centrosome amplification (CA), its evolutionary behaviour within intraclonal heterogeneity as well as its potential impact on the disease progression and MM treatment.

First-in-Human Experience of CXCR4-Directed Endoradiotherapy with 177Lu- and 90Y-Labeled Pentixather in Advanced-Stage Multiple Myeloma with Extensive Intra- and Extramedullary Disease

Chemokine receptor 4 (CXCR4) is a key factor for tumor growth and metastasis in several types of human cancer. Based on promising experiences with a radiolabeled CXCR4 ligand ((68)Ga-pentixafor) for diagnostic receptor targeting, (177)Lu- and (90)Y-pentixather were recently developed as endoradiotherapeutic vectors. Here, we summarize the first-in-human experience in 3 heavily pretreated patients with intramedullary and extensive extramedullary manifestations of multiple myeloma undergoing CXCR4-directed endoradiotherapy.

METHODS

CXCR4 target expression was demonstrated by baseline (68)Ga-pentixafor PET. Each treatment was approved by the clinical ethics committee. Pretherapeutic (177)Lu-pentixather dosimetry was performed before (177)Lu-pentixather or (90)Y-pentixather treatment. Subsequently, patients underwent additional chemotherapy and autologous stem cell transplantation for bone marrow rescue.

RESULTS

A remarkable therapeutic effect was visualized in 2 patients, who showed a significant reduction in (18)F-FDG uptake.

CONCLUSION

CXCR4-targeted radiotherapy with pentixather appears to be a promising novel treatment option in combination with cytotoxic chemotherapy and autologous stem cell transplantation, especially for patients with advanced multiple myeloma.

Flow cytometry in immunoglobulin light chain amyloidosis: Short review

Flow cytometry (FCM) has found its application in clinical diagnosis and evaluation of monoclonal gammopathies (MG). Although, research has been mainly focused on multiple myeloma (MM), nowadays FCM becomes to be potential tool in the field of AL amyloidosis. Clonal plasma cells identification and specific phenotype profile detection is important for diagnosis, monitoring and prognosis of AL amyloidosis. Therefore, FCM could be a perspective method for study not only MM but also AL amyloidosis. This review provides an overview and possibilities of FCM application in AL amyloidosis.

Longitudinal analysis of 25 sequential sample-pairs using a custom multiple myeloma mutation sequencing panel (M(3)P)

Recent advances in genomic sequencing technologies now allow results from deep next-generation sequencing to be obtained within clinically meaningful timeframes, making this an attractive approach to better guide personalized treatment strategies. No multiple myeloma-specific gene panel has been established so far; we therefore designed a 47-gene-targeting gene panel, containing 39 genes known to be mutated in ≥3 % of multiple myeloma cases and eight genes in pathways therapeutically targeted in multiple myeloma (MM). We performed targeted sequencing on tumor/germline DNA of 25 MM patients in which we also had a sequential sample post treatment. Mutation analysis revealed KRAS as the most commonly mutated gene (36 % in each time point), followed by NRAS (20 and 16 %), TP53 (16 and 16 %), DIS3 (16 and 16 %), FAM46C (12 and 16 %), and SP140 (12 and 12 %). We successfully tracked clonal evolution and identified mutation acquisition and/or loss in FAM46C, FAT1, KRAS, NRAS, SPEN, PRDM1, NEB, and TP53 as well as two mutations in XBP1, a gene associated with bortezomib resistance. Thus, we present the first longitudinal analysis of a MM-specific targeted sequencing gene panel that can be used for individual tumor characterization and for tracking clonal evolution over time.

Impact of early use of lenalidomide and low-dose dexamethasone on clinical outcomes in patients with relapsed/refractory multiple myeloma

We retrospectively investigated the prognostic factor of lenalidomide plus low-dose dexamethasone (Rd) in Japanese patients with refractory or relapsed multiple myeloma (RRMM) registered in the Kansai Myeloma Forum from January 2006 to December 2013. A total of 140 patients were analyzed. The median age was 66 years. The overall response rate was 68.6 %, including 33.1 % with a better than very good partial response. At 13.0 months median follow-up, the median overall survival (OS) and progression-free survival (PFS) were 34.2 and 17.0 months, respectively. In univariate analyses, patients with one or two prior therapies had significantly longer OS (41.2 vs. 21.5 months; P = 0.002) and PFS (29.0 vs. 13.0 months; P = 0.006) than patients treated with three or more prior therapies. Prior use of thalidomide was associated with significantly shorter PFS (19.0 vs. 16.0 months; P = 0.045). The prior use of bortezomib or high-dose therapy with stem cell transplantation, and the International Staging System had no impact on long-term outcome. Multivariate analysis showed that only the number of prior therapies was a significant predictor of both OS and PFS. Our findings suggest that greater benefit may occur when Rd therapy is used at the first or second relapse in RRMM.

Next-generation sequencing in multiple myeloma: insights into the molecular heterogeneity of the disease

SUMMARY 

Multiple myeloma (MM) is a still incurable malignant proliferation of clonal bone marrow plasma cells that is characterized by its variable clinical course, biology and molecular and genetic configuration. Given its relatively high incidence among hematological malignancies, a number of studies have taken advantage of large MM cohorts and used global gene, miRNA expression and genome-wide DNA profiling, and – more recently – next-generation sequencing (NGS) technology to investigate the genomic alterations underlying its bioclinical heterogeneity. Although still limited, NGS studies of MM have undoubtedly allowed a finer characterization of the molecular structure underlying the disease by further highlighting its heterogeneity and revealing novel molecular alterations. Herein, we present the main acquisitions on MM knowledge reached by the application of NGS.

Clonal heterogeneity of lymphoid malignancies correlates with poor prognosis

Clonal heterogeneity in lymphoid malignancies has been recently reported in adult T-cell lymphoma/leukemia, peripheral T-cell lymphoma, not otherwise specified, and mantle cell lymphoma. Our analysis was extended to other types of lymphoma including marginal zone lymphoma, follicular lymphoma and diffuse large B-cell lymphoma. To determine the presence of clonal heterogeneity, 332 cases were examined using array comparative genomic hybridization analysis. Results showed that incidence of clonal heterogeneity varied from 25% to 69% among different types of lymphoma. Survival analysis revealed that mantle cell lymphoma and diffuse large B-cell lymphoma with clonal heterogeneity showed significantly poorer prognosis, and that clonal heterogeneity was confirmed as an independent predictor of poor prognosis for both types of lymphoma. Interestingly, 8q24.1 (MYC) gain, 9p21.3 (CDKN2A/2B) loss and 17p13 (TP53, ATP1B2, SAT2, SHBG) loss were recurrent genomic lesions among various types of lymphoma with clonal heterogeneity, suggesting at least in part that alterations of these genes may play a role in clonal heterogeneity.