Design, Synthesis, and Biological Evaluation of Icaritin Derivatives as Novel Putative DEPTOR Inhibitors for Multiple Myeloma Treatment

Research strategies of small molecules as chemotherapeutics to overcome multiple myeloma resistance

Multiple myeloma (MM), a cancer of plasma cells, is the second most common hematological malignancy which is characterized by aberrant plasma cells infiltration in the bone marrow and complex heterogeneous cytogenetic abnormalities. Over the past two decades, novel treatment strategies such as proteasome inhibitors, immunomodulators, and monoclonal antibodies have significantly improved the relative survival rate of MM patients. However, the development of drug resistance results in the majority of MM patients suffering from relapse, limited treatment options and uncontrolled disease progression after relapse. There are urgent needs to develop and explore novel MM treatment strategies to overcome drug resistance and improve efficacy. Here, we review the recent small molecule therapeutic strategies for MM, and introduce potential new targets and corresponding modulators in detail. In addition, this paper also summarizes the progress of multi-target inhibitor therapy and protein degradation technology in the treatment of MM.

Synthesis and cytotoxic evaluation of glycosyl derivatives of icaritin

A series of glycosyl alkyl/triazol-linked icaritin derivatives have been designed and synthesised. The target glycosyl derivatives were evaluated for their anticancer activity against three human cancer cell lines. The results of preliminary anticancer tests in vitro revealed that mannose derivatives 10a-10c (100 μM) with different aliphatic chain lengths exhibited increased cytotoxicity against HepG2 and SK-OV-3 cells compared with the parent compound icaritin. The data indicated that the kind of glycosyl groups and linkers affected the anticancer potency significantly. The ADME analysis of derivatives 10a-10c was also performed.

Is It Still Possible to Think about HSP70 as a Therapeutic Target in Onco-Hematological Diseases?

The search for molecules to be targeted that are involved in apoptosis resistance/increased survival and pathogenesis of onco-hematological malignancies is ongoing since these diseases are still not completely understood. Over the years, a good candidate has been identified in the Heat Shock Protein of 70kDa (HSP70), a molecule defined as “the most cytoprotective protein ever been described”. HSP70 is induced in response to a wide variety of physiological and environmental insults, allowing cells to survive lethal conditions. This molecular chaperone has been detected and studied in almost all the onco-hematological diseases and is also correlated to poor prognosis and resistance to therapy. In this review, we give an overview of the discoveries that have led us to consider HSP70 as a therapeutic target for mono- or combination-therapies in acute and chronic leukemias, multiple myeloma and different types of lymphomas. In this excursus, we will also consider HSP70 partners, such as its transcription factor HSF1 or its co-chaperones whose druggability could indirectly affect HSP70. Finally, we will try to answer the question asked in the title of this review considering that, despite the effort made by research in this field, HSP70 inhibitors never reached the clinic.

Discovery of Novel Phosphoinositide-3-Kinase α Inhibitors with High Selectivity, Excellent Bioavailability, and Long-Acting Efficacy for Gastric Cancer

Phosphoinositide-3-kinase (PI3K) overexpressed in many tumors is a promising target for cancer therapy. However, due to toxicity from the ubiquitous expression of PI3K in many tissues, the development of PI3K inhibitors with high selectivity and low toxicity has become an urgent need for tumor treatment. Herein, based on the HipHop, we designed and synthesized a series of 6-(4,6-dimorpholino-1,3,5-triazin-2-yl)benzo[d]oxazol-2-amine derivatives as potent, selective, and long-acting PI3Kα inhibitors. Compound 27 was determined with potent PI3Kα inhibitory activity (IC₅₀ = 4.4 nM), which exhibited excellent selectivity for homologous PI3K enzymes and a 370 kinome panel. Meanwhile, 27 featured favorable stability (T_1/2 > 10 h) and high bioavailability (130%). Importantly, compound 27 exerted great antigastric cancer activity in vivo when combined with taxol. Collectively, these characteristics suggested 27 to be a promising PI3K agent for cancer treatment.

Longitudinal preclinical evaluation of the novel radioligand [11C]CHDI-626 for PET imaging of mutant huntingtin aggregates in Huntington's disease

Purpose

As several therapies aimed at lowering mutant huntingtin (mHTT) brain levels in Huntington’s disease (HD) are currently being investigated, noninvasive positron emission tomography (PET) imaging of mHTT could be utilized to directly evaluate therapeutic efficacy and monitor disease progression. Here we characterized and longitudinally assessed the novel radioligand [¹¹C]CHDI-626 for mHTT PET imaging in the zQ175DN mouse model of HD.

Methods

After evaluating radiometabolites and radioligand kinetics, we conducted longitudinal dynamic PET imaging at 3, 6, 9, and 13 months of age (M) in wild-type (WT, n = 17) and heterozygous (HET, n = 23) zQ175DN mice. Statistical analysis was performed to evaluate temporal and genotypic differences. Cross-sectional cohorts at each longitudinal time point were included for post-mortem [³H]CHDI-626 autoradiography.

Results

Despite fast metabolism and kinetics, the radioligand was suitable for PET imaging of mHTT. Longitudinal quantification could discriminate between genotypes already at premanifest stage (3 M), showing an age-associated increase in signal in HET mice in parallel with mHTT aggregate load progression, as supported by the post-mortem [³H]CHDI-626 autoradiography.

Conclusion

With clinical evaluation underway, [¹¹C]CHDI-626 PET imaging appears to be a suitable preclinical candidate marker to monitor natural HD progression and for the evaluation of mHTT-lowering therapies.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00259-021-05578-8.