Practical Approaches to the Management of Dual Refractory Multiple Myeloma

The outcome of myeloma patients' dual refractory to lenalidomide and bortezomib is generally poor and represents a significant clinical challenge with a clear need for new therapeutic approaches. This has prompted the development of next-generation proteasome inhibitors and immunodulatory drugs (IMiDs), as well as new classes of drugs with novel mechanisms of action. As a result, several of these agents have received regulatory approval that have shown promising activity in the dual refractory setting including the second-generation proteasome inhibitor carfilzomib and third-generation IMiD pomalidomide. Moreover, the regulatory approval of several first-in-class drugs for myeloma such as the histone deacetylase (HDAC) inhibitor panobinostat and the anti-CD38 monoclonal antibody daratumumab has further broadened the therapeutic landscape for these patients. Collectively, these advances have provided new treatment strategies in dual refractory myeloma as well as important insights for the development of future studies with rationally designed drug combinations to target this challenging patient population.

[Pomalidomide for multiple myeloma]

Pomalidomide is a second-generation immunomodulatory drug (IMID). Its efficiency overtakes its predecessors' (thalidomide, lenalidomide), with less toxicity. It is indicated in the treatment of refractory or relapsed multiple myeloma, associated to dexamethasone. It is available in France since 2013, following the results of different studies.

Successful Intrathecal Chemotherapy Combined with Radiotherapy Followed by Pomalidomide and Low-Dose Dexamethasone Maintenance Therapy for a Primary Plasma Cell Leukemia Patient

Primary plasma cell leukemia (PPCL) is a rare aggressive variant of plasma cell disorder and frequently presents with extramedullary disease. Central nervous system (CNS) involvement with PPCL has an extremely poor prognosis. We describe a 46-year-old man with PPCL treated with a combination of lenalidomide, bortezomib, and dexamethasone as induction therapy following upfront allogeneic stem cell transplantation (allo-SCT). Despite achieving a very good partial response, the patient suffered from an isolated CNS relapse 12 months after allo-SCT. He was immediately started on concurrent intrathecal chemotherapy (IT) and cranial irradiation (RT). Subsequently, pomalidomide and low-dose dexamethasone (Pd) were given as maintenance therapy. He has been without CNS recurrence for more than 18 months. Our case suggests that concurrent IT and RT followed by Pd maintenance therapy may be an effective option to control CNS relapse of PPCL after allo-SCT.

Practical Considerations in Managing Relapsed Multiple Myeloma

Considerable advances have been made in the treatment of relapsed and relapsed/refractory multiple myeloma, with numerous novel agents and combination strategies receiving regulatory approval worldwide during the past several years. An increasing body of phase III data has clearly demonstrated increased overall response rates, improved depths of response, and more durable responses when a third novel agent is incorporated into lenalidomide-dexamethasone and bortezomib-dexamethasone platforms, in most cases with acceptable toxicity. The carfilzomib-dexamethasone doublet has also demonstrated promising activity. With this rapid progress has come many new questions. We review the data supporting the use of these novel treatment paradigms for relapsed/refractory multiple myeloma, discuss the place of autologous and allogeneic hematopoietic stem cell transplantation in this rapidly evolving treatment space, and propose strategies to best use these regimens, considering the disease, host, and previous treatment factors.

Pomalidomide mitigates neuronal loss, neuroinflammation, and behavioral impairments induced by traumatic brain injury in rat

BACKGROUND

Traumatic brain injury (TBI) is a global health concern that typically causes emotional disturbances and cognitive dysfunction. Secondary pathologies following TBI may be associated with chronic neurodegenerative disorders and an enhanced likelihood of developing dementia-like disease in later life. There are currently no approved drugs for mitigating the acute or chronic effects of TBI.

METHODS

The effects of the drug pomalidomide (Pom), an FDA-approved immunomodulatory agent, were evaluated in a rat model of moderate to severe TBI induced by controlled cortical impact. Post-TBI intravenous administration of Pom (0.5 mg/kg at 5 or 7 h and 0.1 mg/kg at 5 h) was evaluated on functional and histological measures that included motor function, fine more coordination, somatosensory function, lesion volume, cortical neurodegeneration, neuronal apoptosis, and the induction of pro-inflammatory cytokines (TNF-α, IL-1β, IL-6).

RESULTS

Pom 0.5 mg/kg administration at 5 h, but not at 7 h post-TBI, significantly mitigated the TBI-induced injury volume and functional impairments, neurodegeneration, neuronal apoptosis, and cytokine mRNA and protein induction. To evaluate underlying mechanisms, the actions of Pom on neuronal survival, microglial activation, and the induction of TNF-α were assessed in mixed cortical cultures following a glutamate challenge. Pom dose-dependently ameliorated glutamate-mediated cytotoxic effects on cell viability and reduced microglial cell activation, significantly attenuating the induction of TNF-α.

CONCLUSIONS

Post-injury treatment with a single Pom dose within 5 h significantly reduced functional impairments in a well-characterized animal model of TBI. Pom decreased the injury lesion volume, augmented neuronal survival, and provided anti-inflammatory properties. These findings strongly support the further evaluation and optimization of Pom for potential use in clinical TBI.

A multicenter phase 2 study of pomalidomide plus dexamethasone in patients with relapsed and refractory multiple myeloma: the Japanese MM-011 trial

Background

The immunomodulatory agent pomalidomide in combination with low-dose dexamethasone has demonstrated efficacy and safety for the treatment of relapsed and refractory multiple myeloma (RRMM) in phase 2 and 3 trials. However, these trials enrolled very few Asian patients.

Methods

This phase 2 study investigated pomalidomide plus low-dose dexamethasone in 36 Japanese patients with RRMM after ≥2 prior therapies.

Results

Patients enrolled in the study had a relatively high disease burden (81 % Durie–Salmon stage II or III) and were heavily pretreated (median, 6.5 prior antimyeloma regimens). The overall response rate was 42 % (1 patient with complete response and 14 with partial response), with an additional 44 % (16 patients) achieving stable disease (SD). Response rates in patients aged ≤65 years and >65 years were 47 and 35 %, respectively. None of the five patients with extramedullary disease achieved a response, with three of them maintaining SD of short duration. Median progression-free survival was 10.1 months after a 7.7-month median follow-up, and the median overall survival was not reached. The most frequent grade ≥3 adverse events (AEs) were neutropenia (64 %), anemia (42 %), and thrombocytopenia (31 %). The most frequent nonhematologic grade ≥3 AEs were pneumonia and decreased appetite (8 % each). Adverse events in patients aged >65 years were similar to those in patients aged ≤65 years, except for a higher rate of grade ≥3 pneumonia.

Conclusions

Collectively, the results of this study demonstrate that pomalidomide plus low-dose dexamethasone is an effective and safe treatment for Japanese patients with RRMM, although careful attention needs to be paid to serious infections.

Trial registration: Clinicaltrials.gov NCT02011113

Oral proteasome inhibitor with strong preclinical efficacy in myeloma models

BACKGROUND

The proteasome is a validated anti-cancer target and various small-molecule inhibitors are currently in clinical development or on the market. However, adverse events and resistance associated with those proteasome inhibitors indicate the need for a new generation of drugs. Therefore, we focused on developing an oral proteasome inhibitor with improved efficacy and safety profiles.

METHOD

The in vitro inhibition of the 20S proteasome catalytic activities was determined in human multiple myeloma (MM) cellular lysates with fluorogenic peptide substrates specific for each catalytic subunit. Cell cytotoxicity was assessed with the ATP bioluminescence assay using human cell samples from tumor cell lines, MM patients or normal healthy donors. In mice bearing human MM xenografts, a single dose of LC53-0110 was administered orally, and concentration-time profiles of LC53-0110 and the 20S proteasome catalytic activities in plasma, blood, and tumor were determined. The efficacy of repeat-dose compound with regard to tumor growth inhibition in vivo was also evaluated in the same MM xenograft models.

RESULTS

LC53-0110 is far more specific for the chymotrypsin-like proteolytic (β5) site of the 20S proteasome as compared to bortezomib, carfilzomib, or ixazomib. LC53-0110 treatment showed accumulation of ubiquitinated proteins, inhibited cell viability with a low nM range potency in various tumor cell lines, and showed potent activity on CD138(+) cells isolated from MM patients who are resistant/refractory to current FDA-approved drug treatment. When a single dose was administered orally to tumor-bearing mice, LC53-0110 showed both greater maximum and sustained tumor proteasome inhibition as compared with ixazomib in MM xenograft models. The robust pharmacodynamic responses in tumor correlated with tumor growth regression. In addition, LC53-0151, an analog of LC53-0110, in combination with pomalidomide, a third-generation immunomodulatory drug, showed synergistic inhibition of tumor growth both in vitro and in the xenograft mouse model.

CONCLUSIONS

In view of the in vitro, in vivo, and ex vivo profiles, further investigation of additional LC compounds in preclinical studies is warranted for the nomination of a clinical development candidate.

Immunomodulatory drugs in AL amyloidosis

Immunoglobulin light chain amyloidosis (AL amyloidosis) is indeed a rare plasma cell disorder, yet the most common of the systemic amyloidoses. The choice of adequate treatment modality is complicated and depends dominantly on the risk stratification of these fragile patients. Immunomodulatory drugs (IMiDs) are currently used in newly diagnosed patients as well as in salvage therapy in relapsed/refractory patients. IMiDs have a pleiotropic effect on malignant cells and the exact mechanism of their action has been described recently. Thalidomide is the most ancient representative, effective but toxic. Lenalidomide seems to be more effective, nevertheless the toxicity remains high, especially in patients with renal insufficiency. Pomalidomide is the newest IMiD used in this indication with a good balance between efficacy and tolerable toxicity and represents the most promising compound. This review is focused on the evaluation of all three representatives of IMiDs and their roles in the treatment of this malignant disorder.

A Phase 1, double-blind, 4-period crossover study to investigate the effects of pomalidomide on QT interval in healthy male subjects

PURPOSE

Pomalidomide is a distinct immunomodulatory agent approved for the treatment of relapsed and refractory multiple myeloma. QT interval was monitored in prior studies, and although there was no indication that pomalidomide could induce QT prolongation, a formal analysis was not previously conducted. Therefore, we present here the results of a study evaluating the effects of pomalidomide on QT interval corrected for heart rate (QTc) using Fridericia's formula (QTcF) and other electrocardiogram (ECG) parameters.

METHODS

Healthy male volunteers with normal or clinically acceptable laboratory tests and ECG results were randomized to receive single oral doses of placebo, pomalidomide 4 mg, pomalidomide 20 mg, and moxifloxacin 400 mg (positive control) in different sequences. Subjects were evaluated by digital ECG monitoring and underwent blood sampling and standard safety monitoring.

RESULTS

Seventy-two subjects were enrolled. In ECG evaluations performed after dosing with pomalidomide 4 mg (therapeutic dose) or 20 mg (supratherapeutic dose), the upper limit of the two-sided 90 % CI for mean change from baseline and placebo-corrected QTcF was <10 ms at all postdose time points, which is below the defined threshold of regulatory concern. In contrast, moxifloxacin induced a clear prolongation in QT interval. Changes in heart rate and other ECG parameters after pomalidomide dosing were clinically insignificant.

CONCLUSIONS

Pomalidomide given as a single oral dose of up to 20 mg was not associated with QT prolongation in healthy male subjects.

Immunomodulatory drugs act as inhibitors of DNA methyltransferases and induce PU.1 up-regulation in myeloma cells

Immunomodulatory drugs (IMiDs) such as thalidomide, lenalidomide, and pomalidomide are efficacious in the treatment of multiple myeloma and significantly prolong their survival. However, the mechanisms of such effects of IMiDs have not been fully elucidated. Recently, cereblon has been identified as a target binding protein of thalidomide. Lenalidomide-resistant myeloma cell lines often lose the expression of cereblon, suggesting that IMiDs act as an anti-myeloma agent through interacting with cereblon. Cereblon binds to damaged DNA-binding protein and functions as a ubiquitin ligase, inducing degradation of IKZF1 and IKZF3 that are essential transcription factors for B and T cell development. Degradation of both IKZF1 and IKZF3 reportedly suppresses myeloma cell growth. Here, we found that IMiDs act as inhibitors of DNA methyltransferases (DMNTs). We previously reported that PU.1, which is an ETS family transcription factor and essential for myeloid and lymphoid development, functions as a tumor suppressor in myeloma cells. PU.1 induces growth arrest and apoptosis of myeloma cell lines. In this study, we found that low-dose lenalidomide and pomalidomide up-regulate PU.1 expression through inducing demethylation of the PU.1 promoter. In addition, IMiDs inhibited DNMT1, DNMT3a, and DNMT3b activities in vitro. Furthermore, lenalidomide and pomalidomide decreased the methylation status of the whole genome in myeloma cells. Collectively, IMiDs exert demethylation activity through inhibiting DNMT1, 3a, and 3b, and up-regulating PU.1 expression, which may be one of the mechanisms of the anti-myeloma activity of IMiDs.

[Pomalidomide for multiple myeloma]

Once characterized by a very poor outcome, multiple myeloma (MM) now has a significantly prolonged survival, with major improvements allowed by the use of "novel agents": proteasome inhibitors (first-in-class bortezomib) and immunomodulatory compounds (IMiDs; first-in-class thalidomide and lenalidomide). However, the vast majority - if not all - of patients with MM ultimately end up being refractory to all existing drugs, including these efficient novel agents. There is a clear unmet medical need in this situation, which warrants the development of the next generation of proteasome inhibitors and IMiDs, as well as new drug classes. This review focuses on pomalidomide, the next generation IMiD, recently approved by the US FDA and the EMA for patients with relapsed or refractory MM who have received at least two prior therapies, including lenalidomide and bortezomib, and have demonstrated disease progression on their last therapy.

Meeting report of the 5th Heidelberg Myeloma Workshop: current status and developments in diagnosis and therapy of multiple myeloma

PURPOSE

The 5th Heidelberg Myeloma Workshop was held on April 24 and 25, 2015, in the lecture hall of the department of internal medicine of the University Hospital of Heidelberg, Germany.

METHODS AND RESULTS

Main topics of the meeting were (1) new insights into biology of plasma cell diseases, (2) familial risk in multiple myeloma (MM), (3) diagnosis and prognostic factors in MM and early plasma cell diseases, (4) frontline therapy in transplant-eligible and (5) transplant-ineligible patients as well as (6) treatment of relapsed disease.

CONCLUSION

Better understanding of disease biology led to tremendous changes in the treatment of multiple myeloma in recent years and were reported during the meeting.

Pomalidomide and Low-Dose Dexamethasone Improves Health-Related Quality of Life and Prolongs Time to Worsening in Relapsed/Refractory Patients With Multiple Myeloma Enrolled in the MM-003 Randomized Phase III Trial

BACKGROUND

Health-related quality of life (HRQoL) is an important element for consideration in treatment decisions in patients with relapsed/refractory multiple myeloma (RRMM). The pivotal MM-003 (A Phase 3, Multicenter, Randomized, Open-Label Study to Compare the Efficacy and Safety of Pomalidomide in Combination With Low-Dose Dexamethasone vs. High-Dose Dexamethasone in Patients With Refractory Multiple Myeloma or Relapsed and Refractory Multiple Myeloma and Companion Study [NIMBUS]) randomized, open-label, multicenter, phase III trial demonstrated improved progression-free survival (PFS) and prolonged overall survival (OS) with pomalidomide (POM) plus low-dose dexamethasone (POM + LoDEX) versus high-dose dexamethasone (HiDEX) in patients with RRMM in whom lenalidomide (LEN) and bortezomib (BORT) had failed. MM-003 also investigated HRQoL as a predefined secondary end point.

PATIENTS AND METHODS

Recruited patients (n = 455) were refractory to their last treatment and had failed LEN and BORT after ≥ 2 consecutive cycles of each (alone or in combination). Eight clinically relevant and validated HRQoL domains from the European Organisation for Research and Treatment of Cancer (EORTC) QLQ-C30, EORTC QLQ-MY20, and EQ-5D questionnaires were selected for analysis. Time to symptom worsening based on minimally important differences (MIDs) was calculated.

RESULTS

Clinically meaningful improvements in HRQoL as determined by MIDs, regression analyses, and best response analyses were observed more frequently in patients receiving POM + LoDEX than in those receiving HiDEX. POM + LoDEX significantly extended median time to clinically meaningful worsening in HRQoL versus HiDEX in 4 HRQoL domains and demonstrated a trend in an additional 3 domains. Patients in the HiDEX arm experienced earlier HRQoL deterioration compared with those in the POM + LoDEX arm in each domain analyzed.

CONCLUSION

POM + LoDEX offer good clinical outcomes that lead to improved and prolonged HRQoL compared with HiDEX in patients with RRMM and end-stage disease.

Long-term disease control by pomalidomide-/dexamethasone-based therapy in a patient with advanced multiple myeloma: a case report and review of the literature

Background

Therapy for multiple myeloma (MM) has substantially improved in the era of immunomodulatory drugs and bortezomib. However, the prognosis of patients with progressive disease despite treatment with these ‘novel agents’ remains poor. Recently, pomalidomide was approved in this setting, but a median progression-free survival of <4 months still leaves room for improvement. Pomalidomide-based combination therapies are currently under investigation, but data on long-term treatment are lacking.

Case Report

We present the case of a 68-year-old woman with refractory MM who received pomalidomide in combination with various drugs including anthracyclines, alkylators and proteasome inhibitors. Initially, major hematological toxicities and infectious complications including a hepatitis B virus reactivation were encountered. With careful dose adjustments and selection of combination partners, pomalidomide treatment was maintained for over 4 years and led to a sustained partial remission. In particular, the well-tolerated regimen of bortezomib, cyclophosphamide and dexamethasone together with pomalidomide was administered for >30 cycles.

Conclusion

This case illustrates the value of an individualized approach to myeloma care given an increasing availability of ‘novel agents’. Tailored treatment using these drugs as a backbone is essential to achieve long-lasting responses and minimize side effects.

Cereblon binding molecules in multiple myeloma

Immunomodulation is an established treatment strategy in multiple myeloma with thalidomide and its derivatives lenalidomide and pomalidomide as its FDA approved representatives. Just recently the method of action of these cereblon binding molecules was deciphered and results from large phase 3 trials confirmed the backbone function of this drug family in various combination therapies. This review details the to-date knowledge concerning mechanism of IMiD action, clinical applications and plausible escape mechanisms in which cells may become resistant/refractory to cereblon binding molecule based treatment.

The European medicines agency review of pomalidomide in combination with low-dose dexamethasone for the treatment of adult patients with multiple myeloma: summary of the scientific assessment of the committee for medicinal products for human use

On August 5, 2013, a marketing authorization valid throughout the European Union (EU) was issued for pomalidomide in combination with dexamethasone for the treatment of adult patients with relapsed and refractory multiple myeloma (MM) who have received at least two prior treatment regimens, including both lenalidomide and bortezomib, and have demonstrated disease progression on the last therapy. Pomalidomide is an immunomodulating agent. The recommended starting dose of pomalidomide is 4 mg once daily taken on days 1-21 of repeated 28-day cycles. The main evidence of efficacy for pomalidomide in MM was based on a phase III multicenter, randomized, open-label study (CC-4047-MM-003) in which pomalidomide plus low-dose dexamethasone therapy (POM+LoDEX) was compared with high-dose dexamethasone alone (HiDEX) in previously treated adult patients with relapsed and refractory multiple myeloma who had received at least two prior treatment regimens, including both lenalidomide and bortezomib, and had demonstrated disease progression on the last therapy. For the intent-to-treat population, median progression-free survival based on International Myeloma Working Group criteria was 15.7 weeks (95% confidence interval [CI]: 13.0-20.1) in the POM+LoDEX group versus 8.0 weeks (95% CI: 7.0-9.0) in the HiDEX group (log-rank p value <.001). Overall survival (secondary endpoint) was also different in the two treatment groups (hazard ratio 0.53 [95% CI: 0.37-0.74]). The most commonly reported adverse reactions to pomalidomide in clinical studies were anemia (45.7%), neutropenia (45.3%) and thrombocytopenia (27%), fatigue (28.3%), pyrexia (21%), peripheral edema (13%), and infections including pneumonia (10.7%). Peripheral neuropathy adverse reactions were reported in 12.3% of patients, and venous embolic or thrombotic (VTE) adverse reactions were reported in 3.3% of patients. Pomalidomide is expected to be teratogenic. This paper summarizes the scientific review of the application leading to approval in the EU. The detailed scientific assessment report and product information, including the summary of product characteristics, are available on the EMA website (http://www.ema.europa.eu).

Design and characterization of 3-Azidothalidomide as a selective hydrogen sulfide probe

Hydrogen sulfide (H2S) has been recently recognized as an important signaling molecule in biological systems. Herein, we report the development of a fluorescence turn-on probe based on the structure of pomalidomide, a FDA approved drug for the treatment of multiple myeloma. Various characterizations demonstrated high selectivity and sensitivity of this probe towards H2S. Furthermore, the application of this probe to detect H2S in living cells was confirmed by flow cytometry and fluorescence imaging studies.

Phase II study of pomalidomide in combination with prednisone in patients with myelofibrosis and significant anemia

We evaluated pomalidomide with prednisone for myelofibrosis (MF) with significant anemia (hemoglobin < 10 g/dL). Patients (n = 29; 18 RBC-transfusion dependent) received 0.5mg pomalidomide daily in continuous 28-day cycles with prednisone given for the first 3 cycles only. Six (21%) patients responded (median response duration 11.4 months), including four who achieved RBC-transfusion-independence per the Delphi criteria and two who achieved clinical improvement (in platelets and spleen, respectively) per the International Working Group for Myelofibrosis Research and Treatment criteria. Grade 3 toxicity occurred in 1 patient (fatigue). Pomalidomide with prednisone is safe therapy with modest activity in patients with MF and anemia. ClinicalTrials.gov Identifier: NCT00946270.

Preclinical and clinical results with pomalidomide in the treatment of relapsed/refractory multiple myeloma

Despite the evolution of effective frontline treatment strategies, many patients with myeloma inevitably relapse. Treatment can be complicated by the interplay of disease-, treatment-, and patient-related factors. Unfortunately, many patients eventually develop disease that is refractory to lenalidomide and bortezomib and have few treatment options. Pomalidomide is a distinct IMiD agent recently approved in the US and Europe. We review the pomalidomide mechanism of action, summarizing its direct antimyeloma, immunomodulatory, and stromal-support inhibitory activities. We also detail its clinical development, including establishment of the approved dose/schedule, phase 2 and 3 trials in relapsed and refractory patients, and novel pomalidomide-based combinations.

A sensitive and robust HPLC assay with fluorescence detection for the quantification of pomalidomide in human plasma for pharmacokinetic analyses

Pomalidomide is a second generation IMiD (immunomodulatory agent) that has recently been granted approval by the Food and Drug Administration for treatment of relapsed multiple myeloma after prior treatment with two antimyeloma agents, including lenalidomide and bortezomib. A simple and robust HPLC assay with fluorescence detection for pomalidomide over the range of 1-500ng/mL has been developed for application to pharmacokinetic studies in ongoing clinical trials in various other malignancies. A liquid-liquid extraction from human plasma alone or pre-stabilized with 0.1% HCl was performed, using propyl paraben as the internal standard. From plasma either pre-stabilized with 0.1% HCl or not, the assay was shown to be selective, sensitive, accurate, precise, and have minimal matrix effects (<20%). Pomalidomide was stable in plasma through 4 freeze-thaw cycles (<12% change), in plasma at room temperature for up to 2h for samples not pre-stabilized with 0.1% HCl and up to 8h in samples pre-stabilized with 0.1% HCl, 24h post-preparation at 4°C (<2% change), and showed excellent extraction recovery (∼90%). This is the first reported description of the freeze/thaw and plasma stability of pomalidomide in plasma either pre-stabilized with 0.1% HCl or not. The information presented in this manuscript is important when performing pharmacokinetic analyses. The method was used to analyze clinical pharmacokinetics samples obtained after a 5mg oral dose of pomalidomide. This relatively simple HPLC-FL assay allows a broader range of laboratories to measure pomalidomide for application to clinical pharmacokinetics.

Pomalidomide for patients with multiple myeloma

Multiple myeloma is a malignancy of plasma cells in the bone marrow. Currently, multiple myeloma is not considered curable, but it is treatable with different strategies that can combine chemotherapy with autologous hematopoietic stem cell transplantation. Pomalidomide is an orally active thalidomide analogue that has a pleiotropic mechanism of action involving oncolytic, antiangiogenic, immunomodulatory and anti-inflammatory activities. Pomalidomide is extensively metabolized, mainly by the cytochrome P450 3A4 and 1A2 pathways. The safety and efficacy of pomalidomide combined with dexamethasone has been demonstrated in a phase III trial for the treatment of multiple myeloma patients, relapsed/resistant to bortezomib and lenalidomide. Adverse events that were mainly related to myelosuppression, were manageable. Pomalidomide has orphan drug status both in the U.S. and Europe for multiple myeloma. It was approved by the U.S. Food and Drug Administration as Pomalyst® for the treatment of multiple myeloma last February, and recently approved in Europe in August.

Sensitive liquid chromatography/mass spectrometry methods for quantification of pomalidomide in mouse plasma and brain tissue

Pomalidomide was recently approved by the United States Food and Drug Administration for the treatment of patients with relapsed or refractory multiple myeloma who have received at least two prior therapies. As pomalidomide is increasingly evaluated in other diseases and animal disease models, this paper presents development and validation of a sensitive liquid chromatography tandem mass spectrometry assay for quantification of pomalidomide in mouse plasma and brain tissue to fill a gap in published preclinical pharmacokinetic and analytical data with this agent. After acetonitrile protein precipitation, pomalidomide and internal standard, hesperitin, were separated with reverse phase chromatography on a C-18 column with a gradient mobile phase of water and acetonitrile with 0.1% fomic acid. Positive atmospheric pressure chemical ionization mass spectrometry with selected reaction monitoring mode was applied to achieve 0.3-3000nM (0.082-819.73ng/mL) linear range in mouse plasma and 0.6-6000pmol/g in brain tissue. The within- and between-batch accuracy and precision were less than 15% for both plasma and brain tissue. The method was applied to measure pomalidomide concentrations in plasma and brain tissue in a pilot mouse pharmacokinetic study with an intravenous dose of 0.5mg/kg. This assay can be applied for thorough characterization of pomalidomide pharmacokinetics and tissue distribution in mice.

Modest activity of pomalidomide in patients with myelofibrosis and significant anemia

We evaluated single agent pomalidomide for myelofibrosis-associated anemia. First, 21 patients received pomalidomide 3.0mg/day on 21-day-on/7-day-off schedule. Due to poor tolerance the study was quickly suspended. Second, 29 patients received pomalidomide 0.5mg/day continuously. Three patients (10%) experienced clinical improvement in hemoglobin per International-Working-Group criteria (median time to response 1.6 months; median response duration 6.7 months). Ten patients were RBC-transfusion-dependent per Delphi criteria; 2 (20%) achieved RBC-transfusion-independence (time to response 0.9 months in both; response duration of 8.3 and 15 months). One grade 3/4 toxicity (neutropenia) occurred. Pomalidomide at low dose is well tolerated but has modest clinical activity in myelofibrosis.

Immunomodulation as a therapeutic strategy in the treatment of multiple myeloma

Growth and survival of multiple myeloma (MM) cells depend on intrinsic, cell-autonomous parameters, such as the genetic lesions harboured by the MM cells, as well as extracellular, cell-non-autonomous factors, including the interaction between MM cells and bone-marrow stromal cells and the suppression of the host's anticancer immune responses. Thalidomide and the immunomodulatory agents lenalidomide and pomalidomide have pleiotropic effects on MM cells and their microenvironment, including promotion of direct mechanisms of MM-cell apoptosis, as well as indirect mechanisms mediated by perturbation of cell adhesion, modulation of cytokine production, and inhibition of tumor-associated angiogenesis. The immunomodulatory properties of these agents are mediated by effects on T-cell proliferation and function, stimulation of natural killer cells, and inhibition of regulatory T cells. Thalidomide and lenalidomide have established roles in the treatment of patients with newly diagnosed MM and those with relapsed/refractory disease. Pomalidomide is currently being evaluated in clinical trials, and preliminary clinical data suggest that it is active in patients with MM that is refractory to lenalidomide and bortezomib treatment. This article provides an overview of the current and potential future roles of immunomodulation in the management of MM, and how improved anticancer immune responses may improve treatment outcomes.