Next-Generation Drugs Targeting the Cereblon Ubiquitin Ligase

Aiolos promotes CXCR3 expression on Th1 cells via positive regulation of IFN-γ/STAT1 signaling

CD4+ T helper 1 (Th1) cells coordinate adaptive immune responses to intracellular pathogens, including viruses. Key to this function is the ability of Th1 cells to migrate within secondary lymphoid tissues, as well as to sites of inflammation, which relies on signals received through the chemokine receptor CXCR3. CXCR3 expression is driven by the Th1 lineage-defining transcription factor T-bet and the cytokine-responsive STAT family members STAT1 and STAT4. Here, we identify the Ikaros zinc finger (IkZF) transcription factor Aiolos (Ikzf3) as an additional positive regulator of CXCR3 both in vitro and in vivo using a murine model of influenza virus infection. Mechanistically, we found that Aiolos-deficient CD4+ T cells exhibited decreased expression of key components of the IFN-γ/STAT1 signaling pathway, including JAK2 and STAT1. Consequently, Aiolos deficiency resulted in decreased levels of STAT1 tyrosine phosphorylation and reduced STAT1 enrichment at the Cxcr3 promoter. We further found that Aiolos and STAT1 formed a positive feedback loop via reciprocal regulation of each other downstream of IFN-γ signaling. Collectively, our study demonstrates that Aiolos promotes CXCR3 expression on Th1 cells by propagating the IFN-γ/STAT1 cytokine signaling pathway.

Efficacy and safety of pomalidomide, bortezomib, and dexamethasone combination chemotherapy for newly diagnosed multiple myeloma: POMACE Phase II Study

Bortezomib, lenalidomide, and dexamethasone induction chemotherapy (VRd), followed by autologous stem cell transplantation (ASCT), are the standard of care for patients with newly diagnosed multiple myeloma (NDMM). Pomalidomide is currently approved for relapsed-refractory multiple myeloma. This single-arm, open-label, phase 2 study was the prospective evaluation of the efficacy and safety of bortezomib, pomalidomide, and dexamethasone (VPd) induction for NDMM. We used Fleming's two-stage design for sample size calculation. We included transplant-eligible and ineligible patients aged 18-75 years in the study. The patients received four cycles of VPd induction followed by response assessment. Thirty-four patients were included in the study, of which 31 completed all four cycles of induction. The median age was 52 years (32-72). Thirty (91%) patients had multiple myeloma, and three had multiple plasmacytomas with less than 10% bone marrow involvement. Nine (27%) had ISS-I, 9 (27%) had ISS-II, and 15 (46%) had ISS-III myeloma. Three patients had high-risk cytogenetic abnormalities. After four cycles of VPd induction, ten patients (32%) achieved stringent CR, nine had CR (29%), eight (26%) had VGPR, and 4 (13%) had PR. Fifteen (48%) had a complete metabolic response (CMR) on PET-CT. Two patients developed SAEs. Anemia was the most common hematological toxicity. Peripheral neuropathy and constipation were the most common non-hematological toxicities. Patients with ≥VGPR had significantly better 12-month PFS than those with PR. Patients with ≥VGPR and CMR on PET-CT had significantly better 12-month OS. Our study showed VPd induction is safe and efficacious in NDMM. Further Phase 3 studies are necessary to establish the superiority and survival benefits.

Design, synthesis and biological evaluation of novel quinazolinone derivatives as CRBN E3 ligase modulators

CRBN E3 ligase modulators, also anteriorly called immunomodulatory drugs (IMiDs), exhibit excellent pharmacological activity by degrading cereblon (CRBN) associated multiple substrates and have become an important field for drug development. These modulators such as Thalidomide, Lenalidomide and CC-122 abduct CRBN to adhere to IKZF1/3 and other neosubstrates, and then induce the degradation of these substrates, thus retarding the further development of related diseases. Herein, we reported a series of CC-122 derivatives that inhibit the proliferation of hematological malignant tumor cell lines. Studies further confirmed that several derivatives which exhibit strong anti-proliferation effect induce the significant degradation of IKZF1/3. In addition, we found that the best compound 14 (SIAIS355035) exhibits better degradation activity and better anti-proliferation activities than CC-122, especially in diffuse large B lymphoma cell lines. Moreover, the PK properties of compound 14 are pretty promising with excellent oral bioavailability. These results clarified the SAR of CC-122 derivatives preliminarily and suggested that compound 14 has great value for further studies as an ideal novel CRBN E3 ligase modulation drug.

A review of the current status of lenalidomide maintenance therapy in multiple myeloma in 2022

INTRODUCTION

Recent advances in the diagnosis and management of multiple myeloma (MM) have improved patient outcomes. This progress in our understanding of MM has resulted in continuous suppressive therapy concepts, including induction, high dose chemotherapy with autologous stem cell transplantation (ASCT), consolidation, and maintenance therapy. The foundation of maintenance therapy has been with lenalidomide. Other novel immunomodulatory drugs (IMiDs), proteasome inhibitors (PIs), and targeted monoclonal antibodies have also contributed to this evolution.

AREAS COVERED

This review summarizes the outcomes from phase II/III trials with long-term lenalidomide maintenance therapy alone or in combination with other agents in post-ASCT and non-transplant settings for newly diagnosed patients with MM. We review recent data considering a combination with newer medications and ongoing trials. We also review the optimal duration, MRD negativity rate, and safety and tolerability aspects of lenalidomide maintenance therapy. This review aims to present the current and emerging clinical evidence that supports using lenalidomide as a backbone for maintenance therapy in patients with MM.

EXPERT OPINION

There is increasing evidence to support lenalidomide as the backbone of combination therapy in the maintenance setting.

A novel Cereblon E3 ligase modulator with antitumor activity in gastrointestinal cancer

Targeted protein degradation offers new opportunities to inactivate cancer drivers and has successfully entered the clinic. Ways to induce selective protein degradation include proteolysis targeting chimera (PROTAC) technology and immunomodulatory (IMiDs) / next-generation Cereblon (CRBN) E3 ligase modulating drugs (CELMoDs). Here, we aimed to develop a MYC PROTAC based on the MYC-MAX dimerization inhibitor 10058-F4 derivative 28RH and Thalidomide, called MDEG-541. We show that a subgroup of gastrointestinal cancer cell lines and primary patient-derived organoids are MDEG-541 sensitive. Although MYC expression was regulated in a CRBN-, proteasome- and ubiquitin-dependent manner, we provide evidence that MDEG-541 induced the degradation of CRBN neosubstrates, including G1 to S phase transition 1/2 (GSPT1/2) and the Polo-like kinase 1 (PLK1). In sum, we have established a CRBN-dependent degrader of relevant cancer targets with activity in gastrointestinal cancers.

Comparison of Clinical Characteristics and Genetic Aberrations of Plasma Cell Disorders in Thailand Population

Multiple myeloma is an incurable malignancy of plasma cells resulting from impaired terminal B cell development. Almost all patients with multiple myeloma eventually have a relapse. Many studies have demonstrated the importance of the various genomic mutations that characterize multiple myeloma as a complex heterogeneous disease. In recent years, next-generation sequencing has been used to identify the genomic mutation landscape and clonal heterogeneity of multiple myeloma. This is the first study, a prospective observational study, to identify somatic mutations in plasma cell disorders in the Thai population using targeted next-generation sequencing. Twenty-seven patients with plasma cell disorders were enrolled comprising 17 cases of newly diagnosed multiple myeloma, 5 cases of relapsed/refractory multiple myeloma, and 5 cases of other plasma cell disorders. The pathogenic mutations were found in 17 of 27 patients. Seventy percent of those who had a mutation (12/17 patients) habored a single mutation, whereas the others had more than one mutation. Fifteen pathogenic mutation genes were identified: ATM, BRAF, CYLD, DIS3, DNMT3A, FBXW7, FLT3, GNA13, IRF4, KMT2A, NRAS, SAMHD1, TENT5C, TP53, and TRAF3. Most have previously been reported to be involved in the RAS/MAPK pathway, the nuclear factor kappa B pathway, the DNA-repair pathway, the CRBN pathway, tumor suppressor gene mutation, or an epigenetic mutation. However, the current study also identified mutations that had not been reported to be related to myeloma: GNA13 and FBXW7. Therefore, a deep understanding of molecular genomics would inevitably improve the clinical management of plasma cell disorder patients, and the increased knowledge would ultimately result in better outcomes for the patients.

N-Adamantyl Phthalimidine: A New Thalidomide-like Drug That Lacks Cereblon Binding and Mitigates Neuronal and Synaptic Loss, Neuroinflammation, and Behavioral Deficits in Traumatic Brain Injury and LPS Challenge

Neuroinflammation contributes to delayed secondary cell death following traumatic brain injury (TBI), has the potential to chronically exacerbate the initial insult, and represents a therapeutic target that has largely failed to translate into human efficacy. Thalidomide-like drugs have effectively mitigated neuroinflammation across cellular and animal models of TBI and neurodegeneration but are complicated by adverse actions in humans. We hence developed N-adamantyl phthalimidine (NAP) as a new thalidomide-like drug to mitigate inflammation without binding to cereblon, a key target associated with the antiproliferative, antiangiogenic, and teratogenic actions seen in this drug class. We utilized a phenotypic drug discovery approach that employed multiple cellular and animal models and ultimately examined immunohistochemical, biochemical, and behavioral measures following controlled cortical impact (CCI) TBI in mice. NAP mitigated LPS-induced inflammation across cellular and rodent models and reduced oligomeric α-synuclein and amyloid-β mediated inflammation. Following CCI TBI, NAP mitigated neuronal and synaptic loss, neuroinflammation, and behavioral deficits, and is unencumbered by cereblon binding, a key protein underpinning the teratogenic and adverse actions of thalidomide-like drugs in humans. In summary, NAP represents a new class of thalidomide-like drugs with anti-inflammatory actions for promising efficacy in the treatment of TBI and potentially longer-term neurodegenerative disorders.

A Cell-Based Target Engagement Assay for the Identification of Cereblon E3 Ubiquitin Ligase Ligands and Their Application in HDAC6 Degraders

Proteolysis-targeting chimeras (PROTACs) is a paradigm shift for small-molecule drug discovery. However, limited E3 ubiquitin ligase ligands with cellular activity are available. In vitro binding assays involve the expression and purification of a large amount of proteins and they often yield ligands that are inactive in cell-based assays due to poor cell permeability, stability, and other reasons. Herein, we report the development of a practical and efficient cell-based target engagement assay to evaluate the binding affinity of a small library of cereblon ligands to its E3 ligase in cells. Selected cell-permeable E3 ligase ligands derived from this assay are then used to construct HDAC6 degraders with cellular protein degradation activity. Because the assay does not involve any genetic engineering, it is relatively easy to transfer from one cell type to a different one.

Antitumor effect of lenalidomide in malignant glioma cell lines

Glioblastoma is a malignant brain tumor exhibiting highly aggressive proliferation and invasion capacities. Despite treatment by aggressive surgical resection and adjuvant therapy including temozolomide and radiation therapy, patient prognosis remains poor. Lenalidomide, a derivative of thalidomide, is known to be an immunomodulatory agent that has been used to treat hematopoietic malignancies. There are numerous studies revealing an antitumor effect of lenalidomide in hematopoietic cells, but not in glioma cells. The present study aimed to demonstrate the antitumor effect of lenalidomide on malignant glioma cell lines. The growth inhibition of malignant glioma cells (A-172, AM-38, T98G, U-138MG, U-251MG, and YH-13) by lenalidomide was assessed using a Coulter counter. The mechanism of the antitumor effect of lenalidomide was examined employing a fluorescence-activated cell sorter, western blot analysis, and quantitative real-time reverse transcriptional polymerase chain reaction (RT-qPCR) in malignant glioma cell lines (A-172, AM-38). The results revealed that the number of malignant glioma cells was decreased in a concentration-dependent manner by lenalidomide. DNA flow cytometric analysis demonstrated an increase in the ratio of cells at the G₀/G₁ phase following lenalidomide treatment. Western blot analysis and RT-qPCR revealed that p53 activation and the expression of p21 were increased in glioma cells treated with lenalidomide. Western blot analysis revealed that cleavage of PARP did not occur; however, increased expression of Bax protein, cleavage of caspase-9 and cleavage of caspase-3 were confirmed. Analysis by FACS also supported the conclusion that little apoptosis induction occurred following lenalidomide treatment of malignant glioma cell lines. In conclusion, lenalidomide exerts an antitumor effect on glioma cells due to alterations in cell cycle distribution.