Phthalimide as a versatile pharmacophore scaffold: Unlocking its diverse biological activities

Phthalimide, a pharmacophore exhibiting diverse biological activities, holds a prominent position in medicinal chemistry. In recent decades, numerous derivatives of phthalimide have been synthesized and extensively studied for their therapeutic potential across a wide range of health conditions. This comprehensive review highlights the latest developments in medicinal chemistry, specifically focusing on phthalimide-based compounds that have emerged within the last decade. These compounds showcase promising biological activities, including anti-inflammatory, anti-Alzheimer, antiepileptic, antischizophrenia, antiplatelet, anticancer, antibacterial, antifungal, antimycobacterial, antiparasitic, anthelmintic, antiviral, and antidiabetic properties. The physicochemical profiles of the phthalimide derivatives were carefully analyzed using the online platform pkCSM, revealing the remarkable versatility of this scaffold. Therefore, this review emphasizes the potential of phthalimide as a valuable scaffold for the development of novel therapeutic agents, providing avenues for the exploration and design of new compounds.

RNF126, 168 and CUL1: The Potential Utilization of Multi-Functional E3 Ubiquitin Ligases in Genome Maintenance for Cancer Therapy

Ubiquitination is a post-translational modification (PTM) that is involved in proteolysis, protein-protein interaction, and signal transduction. Accumulation of mutations and genomic instability are characteristic of cancer cells, and dysfunction of the ubiquitin pathway can contribute to abnormal cell physiology. Because mutations can be critical for cells, DNA damage repair, cell cycle regulation, and apoptosis are pathways that are in close communication to maintain genomic integrity. Uncontrolled cell proliferation due to abnormal processes is a hallmark of cancer, and mutations, changes in expression levels, and other alterations of ubiquitination factors are often involved. Here, three E3 ubiquitin ligases will be reviewed in detail. RNF126, RNF168 and CUL1 are involved in DNA damage response (DDR), DNA double-strand break (DSB) repair, cell cycle regulation, and ultimately, cancer cell proliferation control. Their involvement in multiple cellular pathways makes them an attractive candidate for cancer-targeting therapy. Functional studies of these E3 ligases have increased over the years, and their significance in cancer is well reported. There are continuous efforts to develop drugs targeting the ubiquitin pathway for anticancer therapy, which opens up the possibility for these E3 ligases to be evaluated for their potential as a target protein for anticancer therapy.

Design, synthesis, and biological evaluation of a novel series of 2-(2,6-dioxopiperidin-3-yl)isoquinoline-1,3(2H,4H)-dione derivatives as cereblon modulators

In the current study, we designed and synthesised a novel series of 2-(2,6-dioxopiperidin-3-yl)isoquinoline-1,3(2H,4H)-dione derivatives as cereblon (CRBN) modulators. The results of the CCK8 assay revealed potent antiproliferative activity for the selected compound 10a against NCI-H929 (IC₅₀=2.25 µM) and U239 (IC₅₀=5.86 µM) cell lines. Compound 10a also can inhibit the TNF-α level (IC₅₀=0.76 µM) in LPS stimulated PMBC and showed nearly no toxicity to this normal human cell line. The TR-FRET assay showed compound 10a having potent inhibitory activity against CRBN (IC₅₀=4.83 µM), and the docking study confirmed a nice fitting of 10a into the active sites of CRBN. Further biology studies revealed compound 10a can increase the apoptotic events, arrest the NCI-H929 cells at G0/G1 cell cycle, and induce the ubiquitination degradation of IKZF1 and IKZF3 proteins by CRL4^CRBN. These preliminary results suggested that compound 10a could serve as a potential antitumor drug and worthy of further investigation.

Advances in the Treatment of Relapsed and Refractory Multiple Myeloma in Patients with Renal Insufficiency: Novel Agents, Immunotherapies and Beyond

BACKGROUND

Renal insufficiency is one of the most frequent complications in multiple myeloma. The incidence of renal insufficiency in patients with multiple myeloma ranges from 20% to 50%. Renal impairment in patients with multiple myeloma results primarily from the toxic effects of monoclonal light chains on the kidneys. Dehydration, hypercalcemia, hyperuricemia, the application of nephrotoxic NSARs, antibiotics, contrast agents, etc., all play a major role in the deterioration of renal function in patients with multiple myeloma. The diagnosis and treatment of these patients use an interdisciplinary approach in consultation with hematologist-oncologists, radiologists, nephrologists and intensive care specialists. Using new drugs in the treatment of patients with refractory/relapsed multiple myeloma and renal insufficiency markedly improves progression-free survival and overall survival in these patients.

CONCLUSIONS

New drugs have helped to widen the treatment options available for patients with renal impairment and refractory/relapsed multiple myeloma, since dose adjustments are unnecessary with carfilzomib as well as with panobinostat, elotuzumab, pomalidomide or daratumumab in patients with renal impairment. Several new substances for the treatment of refractory/relapsed multiple myeloma have been approved in the meantime, including belantamab mafodotin, selinexor, melflufen, venetoclax, CAR T-cell therapy and checkpoint inhibitors. Ongoing studies are investigating their administration in patients with renal impairment.

Design, synthesis and biological evaluation of thioether-containing lenalidomide and pomalidomide derivatives with anti-multiple myeloma activity

Lenalidomide and its analogs are well-known for treating multiple myeloma. In this work, designed sulfide-modified lenalidomide and pomalidomide were synthesized and evaluated. The anti-proliferative activity against MM.1S cell line of 3ak (IC₅₀ = 79 nM) was similar to lenalidomide (IC₅₀ = 81 nM). Compared to benzylic thioether substituted lenalidomide 3a, the half-live (T_1/2) of 4-F-phenyl-thioether analogs 3ak in human liver microsomes was promoted from 3 min to 416.7 min. The corresponding metabolic factor of 3ak was increased from 2.8% to 79.5%, which was slightly lower than lenalidomide (91.5%). Moreover, the IKZF1 degradation of 3y and 3ak was well related with corresponding IC₅₀ values, which suggested the IKZF1 degradation efficiency is correlated to the responses of MM1. S cells. Furthermore, the oral administration of compounds 3y and 3ak at dosages of 60 mg/kg could delay tumor growth in female CB-17 SCID mice. This research helped to prompt the stability of thioether lenalidomide analogs, which paved the way for developing better molecules for treating multiple myeloma.

Baicalein Inhibits Proliferation of Myeloma U266 Cells by Downregulating IKZF1 and IKZF3

BACKGROUND Baicalein can suppress the growth of multiple tumors, including multiple myeloma (MM), but the exact mechanisms remains elusive. Here, we investigated the exact mechanisms of the anti-myeloma activity of baicalein. MATERIAL AND METHODS Proliferation and rates of apoptosis of myeloma U266 cells exposed to baicalein were detected. Microarray, polymerase chain reaction (PCR) assay, and Western blot analysis were applied to evaluate the mRNA and protein levels of associated molecules. Survival analysis of IKZF1 and IKZF3 was conducted as well. RESULTS Baicalein suppressed the growth and stimulated apoptosis of myeloma U266 cells in a dose- and time-dependent way. Baicalein increased mRNA level of CRBN, and further studies suggested that baicalein downregulated IKZF1 and IKZF3 on a post-transcriptional level. Although the differences did not reach statistical significance, IKZF1 and IKZF3 were associated with poor overall survival. CONCLUSIONS Our results suggest that baicalein suppresses the growth and promotes apoptosis of myeloma U266 cells through downregulating IKZF1 and IKZF3. Baicalein increased the expression of CRBN, which might exert a reversion effect on resistance of IMiDs. MM patients in IKZF1 and IKZF3 low-expression groups had better overall survival than those in IKZF1 and IKZF3 high-expression groups. Thus, the present results indicate that baicalein might be a therapeutic choice for targeting IKZF1 and IKZF3.

Effect of pomalidomide on relapsed/refractory multiple myeloma: a systematic review and meta-analysis

In this work, we aim to further analyze the effect of pomalidomide for relapsed and/or refractory multiple myeloma (RRMM). A systematic literature search of PubMed, MEDLINE and EMBASE was conducted on September 20, 2016. Pooled effect size (ES) with corresponding 95% confidence intervals (CIs) were calculated using random-effects model. STATA software (version 12.0; Stata Corporation; College Station, TX, USA) was employed to do all statistical analyses. A total of 8 studies were included for analysis. The combined results demonstrated that the pooled proportion of overall response rate (ORR) was 0.35 (95% CI 0.27 to 0.43, P=0.000), and the pooled proportion of complete response rate (CRR) was 0.02 (95% CI 0.01 to 0.03, P=0.541). Pomalidomide was generally well tolerated by patients reported in the studies. Further studies would be required to conduct more prospective randomized controlled trials (RCTs) with larger samples to assess the proper place of pomalidomide as single agent or combined with other agents for RRMM.

A Novel Green Synthesis of Thalidomide and Analogs

Thalidomide and its derivatives are currently under investigation for their antiangiogenic, immunomodulative, and anticancer properties. Current methods used to synthesize these compounds involve multiple steps and extensive workup procedures. Described herein is an efficient microwave irradiation green synthesis method that allows preparation of thalidomide and its analogs in a one-pot multicomponent synthesis system. The multicomponent synthesis system developed involves an array of cyclic anhydrides, glutamic acid, and ammonium chloride in the presence of catalytic amounts of 4-N,N-dimethylaminopyridine (DMAP) to produce thalidomide and structurally related compounds within minutes in good isolated yields.

Association between complete response and outcomes in transplant-eligible myeloma patients in the era of novel agents

OBJECTIVES

Achieving complete response (CR) has been linked to improved progression-free (PFS) and overall (OS) survival in myeloma. A meta-analysis was conducted to investigate whether this holds true in the era of novel agents (bortezomib, lenalidomide, thalidomide).

METHODS

A total of 24 studies in newly diagnosed patients undergoing autologous stem cell transplantation (ASCT) that reported associations between responses and long-term outcomes (PFS/OS rates post-ASCT by response, or hazard ratios with 95% confidence intervals from Cox models) were identified and analyzed.

RESULTS

Achievement of CR vs. <CR post-ASCT reduced risk of progression/death by 38% [risk ratio (RR): 0.62, P < 0.0001]; risk of death was 41% lower (RR: 0.59, P < 0.0001). Subgroup meta-analyses showed significant PFS risk reduction with CR post-ASCT with novel (RR: 0.32, P < 0.006) and non-novel (RR: 0.72, P < 0.0001) agents, and corresponding OS risk reduction with novel (RR: 0.33, P = 0.0013) and non-novel (RR: 0.64, P < 0.0001) agents. Risk reduction was greater with novel vs. non-novel agents (PFS: P = 0.047; OS: P = 0.058).

CONCLUSIONS

Achieving CR during first-line therapy remains important in the novel-agent era; magnitude of association between achieving CR and outcomes appears higher for CR obtained using novel vs. non-novel agents.

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.