Therapeutic use of immunomodulatory drugs in the treatment of multiple myeloma

Ligands for cereblon: 2017-2021 patent overview

INTRODUCTION

Cereblon (CRBN), the substrate receptor of the CRL4^CRBN E3 ubiquitin ligase has been extensively studied due to its involvement in many biological processes. It has also been identified as the target for immunomodulatory drugs (IMiDs). CRBN ligands are also important components of proteolysis-targeting chimeras (PROTACs), special bifunctional constructs capable of targeted degradation of aberrantly acting proteins using the cell's ubiquitin-proteasome machinery.

AREAS COVERED

Due to upsurge of the PROTAC technology, the patenting activity of new CRBN ligands has been on the rise in the last 5 years. The present review covers two broadly defined areas of CRBN ligand design. One covers 'thalidomide-like' molecules representing modifications of various parts of classical IMiDs. The other areas - non-thalidomide-like compounds - are compounds that are structurally distinct from the classical IMiDs. Efforts toward creating new CRBN ligands reflected in non-patent literature are briefly discussed with emphasis on the rational, crystallography-driven approaches.

EXPERT OPINION

The chemical space of CRBN ligands which is related to the classical IMiDs (thalidomide/lenalidomide/pomalidomide) is comprehensively covered by the current patent literature. The promising area of research is in the identification of non-thalidomide-like chemotypes capable of binding to CRBN. Rational, crystallography-driven approaches currently exploited in academia will significantly aid in this endeavor.

Lenalidomide increases human dendritic cell maturation in multiple myeloma patients targeting monocyte differentiation and modulating mesenchymal stromal cell inhibitory properties

The use of Lenalidomide (LEN), to reverse tumor-mediated immune suppression and amplify multiple myeloma-specific immunity is currently being explored. Particularly, LEN effects on dendritic cells (DCs) are still unclear. In this study, we investigated the potential effect of LEN on DC differentiation and activity. DCs were differentiated either from CD14⁺ cells obtained from patients with multiple myeloma or from a human monocytic cell line. LEN, at the concentration range reached in vivo, significantly increased the median intensity expression of HLA-DR, CD86 and CD209 by DCs derived from both bone marrow and peripheral myeloma monocytes and enhanced the production of Interleukin-8, C-C motif chemokine ligand (CCL) 2, CCL5 and tumor necrosis factor-α. Consistently, LEN pre-treated DCs showed an increased ability to stimulate autologous CD3⁺ cell proliferation. LEN effect on dendritic differentiation was associated with the degradation of the Cereblon-related factors Ikaros and Aiolos. Moreover, we showed that LEN also blunted mesenchymal stromal cell inhibitory effect on dendritic differentiation, inhibiting Casein Kinase-1α levels. Finally, in vitro data were confirmed in ex vivo cultures obtained from relapsed myeloma patients treated with LEN, showing a significant increase of DC differentiation from peripheral blood monocytes. In conclusion, LEN increased the expression of mature dendritic markers both directly and indirectly and enhanced DC ability to stimulate T cell proliferation and to release chemokines. This suggests a new possible mechanism by which LEN could exert its anti-myeloma activity.

Paradoxical effect of lenalidomide on cytokine/growth factor profiles in multiple myeloma

Background:

Lenalidomide is an active immunomodulatory and antiproliferative agent in multiple myeloma. However, the molecular mechanisms driving these activities are not yet fully elucidated. Therefore, we investigated the modulation of the cytokine/growth factor patterns of myeloma cells under LEN treatment.

Methods:

Lenalidomide effect on myeloma cell proliferation was investigated in a myeloma cell line collection (n=23) by ³H-thymidine incorporation. Modulation of the cytokine/growth factor patterns of myeloma cells under LEN treatment was analysed by real-time quantitative PCR.

Results:

Lenalidomide inhibits the proliferation of two-thirds of myeloma cell lines independently of their genetic background. We demonstrated that LEN increased TNF-α and IL-8 inflammatory cytokines and insulin-like growth factor-1 (IGF-1) growth factor in both sensitive and resistant myeloma cells to LEN.

Conclusion:

Lenalidomide favours a uniform TNF-α and IL-8 inflammatory and IGF-1 secretory profile of myeloma cells, an observation that raises important questions for therapeutic approaches incorporating the agent.

New strategies in the treatment of multiple myeloma

Multiple myeloma is the second most common hematologic malignancy affecting terminally differentiated plasma cells. Although high-dose chemotherapy and autologous stem cell transplantation have improved survival in younger patients, the natural history of multiple myeloma has been changed with the availability of six new agents approved in the past 10 years (thalidomide, bortezomib, lenalidomide, liposomal doxorubicin, carfilzomib, and pomalidomide). Despite this significant improvement in the overall outcome, multiple myeloma remains incurable in the majority of patients, prompting a continued search for additional therapeutic options. Extensive molecular and genomic characterization of multiple myeloma cells in their bone marrow milieu, which affects myeloma cell growth and survival, has provided a number of novel drugable targets and pathways. Perturbation of protein catabolism at multiple levels has become an important target in multiple myeloma. Similarly, improvements in monoclonal antibody generation and vaccine development, along with identification of a number of cell surface and cellular targets, have led to the development of various strategies, including antibodies and antibody-drug conjugates that are under investigation preclinically and in early clinical studies. We propose that eventually, molecularly informed multiagent combination therapies will be required to eliminate the multiple myeloma cell clone for long-term disease control.

Trace determination of lenalidomide in plasma by non-extractive HPLC procedures with fluorescence detection after pre-column derivatization with fluorescamine

BACKGROUND

Lenalidomide (LND) is a new potent drug used for treatment of multiple myeloma. For its pharmacokinetic studies and therapeutic monitoring, a proper analytical method was required.

RESULTS

In this study, a non extractive and simple pre-column derivatization procedures have been proposed, for the for trace determination of lenalidomide (LND) in human plasma by HPLC with fluorescence detection. Plasma samples were treated with acetonitrile for protein precipitation then treated with copper acetate to form stable complexes with the biogenic amines and mask their interference with the derivatization reaction of LND. Treated plasma samples containing LND was derivatized with fluorescamine (FLC) in aqueous media at ambient temperature. Separation of the derivatized LND was performed on Hypersil BDS C18 column (250 × 4.6 mm, 5 μm particle size) using a mobile phase consisting of phosphate buffer (pH 4):methanol: tetrahydrofuran (70:10:20, v/v) at a flow rate of 1.0 mL/min. The derivatized samples were monitored at an emission wavelength of 495 nm after excitation at a wavelength of 382 nm. Under the optimum chromatographic conditions, a linear relationship with good correlation coefficient (r = 0.9997, n = 9) was found between the peak area and LND concentrations in the range of 2-100 ng/mL. The limits of detection and quantitation were 0.8 and 2.30 ng/mL, respectively. The intra- and inter-assay precisions were satisfactory and the accuracy of the method was proved. The recovery of LND from the spiked human plasma was 99.30 ± 2.88.

CONCLUSIONS

The proposed method had high throughput as the analysis involved simple sample pre-treatment procedure and a relatively short run-time (< 15 min). The results demonstrated that the method would have a great value when it is applied in the therapeutic monitoring and pharmacokinetic studies for LND.

Synthesis of hapten and preparation of specific polyclonal antibody with high affinity for lenalidomide, the potent drug for treatment of multiple myeloma

BACKGROUND

For therapeutic monitoring and pharmacokinetic studies of lenalidomide (LND), the potent drug for treatment of multiple myeloma (MM), a specific antibody was required for the development of a sensitive immunoassay system for the accurate determination of LND in plasma.

RESULTS

In this study, a hapten of LND (N-glutaryl-LND) was synthesized by introducing the glutaryl moiety, as a spacer, into the primary aromatic amine site of the LND molecular structure. The structure of the hapten (G-LND) was confirmed by mass, 1H-NMR, and 13C spectrometric techniques. G-LND was coupled to each of bovine serum albumin (BSA) and keyhole limpet hemocyanin (KLH) proteins by ethyl-3-(3-dimethylaminopropyl) carbodiimide as a coupling reagent. LND-KLH conjugate was used as an immunogen. Four female 2-3 months old New Zealand white rabbits were immunized with an emulsion of LND-KLH with Freund`s adjuvant. The immune response of the rabbits was monitored by direct enzyme-linked immunosorbent assay (ELISA) using LND-BSA immobilized onto microwell plates as a solid phase. The rabbit that showed the highest antibody titer and affinity to LND was scarified and its sera were collected. The IgG fraction was isolated and purified by affinity chromatography on protein A column. The specificity of the purified antibody for LND was evaluated by indirect competitive ELISA using dexamethasone as a competitor as it is used with LND in a combination therapy.

CONCLUSIONS

The high affinity of the antibody (IC50 = 10 ng/mL) will be useful in the development of an immunoassay system for the determination of plasma LND concentrations. Current research is going to optimize the assay conditions and validate the procedures for the routine application in clinical laboratories.

Preclinical activity of P276-00, a novel small-molecule cyclin-dependent kinase inhibitor in the therapy of multiple myeloma

Cyclin D dysregulation and overexpression is noted in the majority of multiple myeloma (MM) patients, suggesting its critical role in MM pathogenesis. Here, we sought to identify the effects of targeting cyclin D in MM. We first confirmed cyclin D mRNA overexpression in 42 of 64 (65%) patient plasma cells. Silencing cyclin D1 resulted in >50% apoptotic cell death suggesting its validity as a potential therapeutic target. We next evaluated P276-00, a clinical-grade small-molecule cyclin-dependent kinase inhibitor as a way to target the cyclins. P276-00 resulted in dose-dependent cytotoxicity in MM cells. Cell-cycle analysis confirmed either growth arrest or caspase-dependent apoptosis; this was preceded by inhibition of Rb-1 phosphorylation with associated downregulation of a range of cyclins suggesting a regulatory role of P276-00 in cell-cycle progression through broad activity. Proliferative stimuli such as interleukin-6, insulin-like growth factor-1 and bone-marrow stromal cell adherence induced cyclins; P276-00 overcame these growth, survival and drug resistance signals. Because the cyclins are substrates of proteasome degradation, combination studies with bortezomib resulted in synergism. Finally, in vivo efficacy of P276-00 was confirmed in an MM xenograft model. These studies form the basis of an ongoing phase I study in the treatment of relapsed/refractory MM.

Lenalidomide: a new therapy for multiple myeloma

The last decade has seen rapid evolution in the management of multiple myeloma. Cytogenetic, molecular, and proteomic techniques have led to a better understanding of the pathophysiology and prognostic markers of this heterogeneous malignancy. New immunomodulatory drugs, such as lenalidomide, which interrupt myeloma growth and survival pathways have entered into clinical usage. Combined with dexamethasone, oral lenalidomide has proved to be highly effective in patients whose disease has become resistant to conventional therapy. Currently, several clinical trials are ongoing in order to define the optimal use of this new agent and its combinations across the spectrum of patients with myeloma. Whether the ultimate outcome of future research will be a single-treatment solution for all patients, or whether treatments will become better-tailored to the individual (based on prognostic markers and pre-existing co-morbidities) has yet to be determined.

Advances in Anti-Inflammatory Therapeutics: 20-21 November 2006, London, UK

This meeting highlighted early discovery to early clinical development of anti-inflammatory drugs. New compounds included kinase inhibitors, receptor modulators and an extended use for an existing drug, lenalidomide, in a further indication. Risk mitigation strategies to improve the likelihood of clinical success was a dominant feature of the meeting.