[Updates in hormone-receptor-positive, human epidermal growth factor receptor 2 (HER2)-negative advanced breast cancer in 2021]. / Actualités 2021 sur le cancer du sein localement avancé ou métastatique RH+/HER2−.

Overall, 2021 was marked by the confirmation of the major interest of cell cycle inhibitors for hormone receptor (HR) positive/human epidermal growth factor receptor 2 (HER2) negative advanced breast cancers with very high overall survival data exceeding five years for hormone-sensitive disease. Studies have also confirmed the efficacy and safety of this therapeutic class in the elderly population. New cell cycle inhibitors are under development (SHR6390). New combinations are also being evaluated, notably palbociclib with SAR439859 (a new selective estrogen receptor degrader: SERD). Targeting of the Phosphoinositide 3-kinases (PI3K) pathway by taselisib, in hormone-resistant disease with a Phosphatidylinositol-4,5-Bisphosphate 3-Kinase Catalytic Subunit Alpha (PIK3CA) mutation, modestly improves progression-free survival but with a non-negligible toxicity of the treatment.

Discovery of 3,4-Dihydrobenzo[f][1,4]oxazepin-5(2H)-one Derivatives as a New Class of Selective TNIK Inhibitors and Evaluation of Their Anti-Colorectal Cancer Effects.

The Traf2- and Nck-interacting protein kinase (TNIK) is a downstream signal protein of the Wnt/ß-catenin pathway and has been thought of as a potential target for the treatment of colorectal cancer (CRC) that is often associated with dysregulation of Wnt/ß-catenin signaling pathway. Herein, we report the discovery of a series of 3,4-dihydrobenzo[f][1,4]oxazepin-5(2H)-one derivatives as a new class of TNIK inhibitors. Structure-activity relationship (SAR) analyses led to the identification of a number of potent TNIK inhibitors with compound 21k being the most active one (IC50: 0.026 ± 0.008 µM). This compound also displayed excellent selectivity for TNIK against 406 other kinases. Compound 21k could efficiently suppress CRC cell proliferation and migration in in vitro assays and exhibited considerable antitumor activity in the HCT116 xenograft mouse model. It also showed favorable pharmacokinetic properties. Overall, 21k could be a promising lead compound for drug discovery targeting TNIK and deserves further studies.

RTK-Dependent Inducible Degradation of Mutant PI3Kα Drives GDC-0077 (Inavolisib) Efficacy.

PIK3CA is one of the most frequently mutated oncogenes; the p110a protein it encodes plays a central role in tumor cell proliferation. Small-molecule inhibitors targeting the PI3K p110a catalytic subunit have entered clinical trials, with early-phase GDC-0077 studies showing antitumor activity and a manageable safety profile in patients with PIK3CA-mutant breast cancer. However, preclinical studies have shown that PI3K pathway inhibition releases negative feedback and activates receptor tyrosine kinase signaling, reengaging the pathway and attenuating drug activity. Here we discover that GDC-0077 and taselisib more potently inhibit mutant PI3K pathway signaling and cell viability through unique HER2-dependent mutant p110a degradation. Both are more effective than other PI3K inhibitors at maintaining prolonged pathway suppression. This study establishes a new strategy for identifying inhibitors that specifically target mutant tumors by selective degradation of the mutant oncoprotein and provide a strong rationale for pursuing PI3Kα degraders in patients with HER2-positive breast cancer. SIGNIFICANCE: The PI3K inhibitors GDC-0077 and taselisib have a unique mechanism of action; both inhibitors lead to degradation of mutant p110a protein. The inhibitors that have the ability to trigger specific degradation of mutant p110a without significant change in wild-type p110a protein may result in improved therapeutic index in PIK3CA-mutant tumors.See related commentary by Vanhaesebroeck et al., p. 20.This article is highlighted in the In This Issue feature, p. 1.

A novel class of oxazepine-based anti-cancer agents induces cell death in primary human CLL cells and efficiently reduces tumor growth in Eµ-TCL1 mice through the JNK/STAT4/p66Shc axis.

Survival and expansion of malignant B cells in chronic lymphocytic leukemia (CLL) are highly dependent both on intrinsic defects in the apoptotic machinery and on the interactions with cells and soluble factors in the lymphoid microenvironment. The adaptor protein p66Shc is a negative regulator of antigen receptor signaling, chemotaxis and apoptosis whose loss in CLL B cells contributes to their extended survival and poor prognosis. Hence, the identification of compounds that restore p66Shc expression and function in malignant B cells may pave the way to a new therapeutic approach for CLL. Here we show that a novel oxazepine-based compound (OBC-1) restores p66Shc expression in primary human CLL cells by promoting JNK-dependent STAT4 activation without affecting normal B cells. Moreover, we demonstrate that the potent pro-apoptotic activity of OBC-1 in human leukemic cells directly correlates with p66Shc expression levels and is abrogated when p66Shc is genetically deleted. Preclinical testing of OBC-1 and the novel analogue OBC-2 in Eµ-TCL1 tumor-bearing mice resulted in a significantly longer overall survival and a reduction of the tumor burden in the spleen and peritoneum. Interestingly, OBCs promote leukemic cell mobilization from the spleen to the blood, which correlates with upregulation of sphingosine-1-phosphate receptor expression. In summary, our work identifies OBCs as a promising class of compounds that, by boosting p66Shc expression through the activation of the JNK/STAT4 pathway, display dual therapeutic effects for CLL intervention, namely the ability to mobilize cells from secondary lymphoid organs and a potent pro-apoptotic activity against circulating leukemic cells.

Mevalonate Kinase Deficiency and Squalene Synthase Inhibitor (TAK-475): The Balance to Extinguish the Inflammation.

Mevalonate Kinase Deficiency (MKD) is a rare inborn disease belonging to the family of periodic fever syndromes. The MKD phenotype is characterized by systemic inflammation involving multiple organs, including the nervous system. Current anti-inflammatory approaches to MKD are only partially effective and do not act specifically on neural inflammation. According to the new emerging pharmacology trends, the repositioning of drugs from the indication for which they were originally intended to another one can make mechanistic-based medications easily available to treat rare diseases. According to this perspective, the squalene synthase inhibitor Lapaquistat (TAK-475), originally developed as a cholesterol-lowering drug, might find a new indication in MKD, by modulating the mevalonate cholesterol pathway, increasing the availability of anti-inflammatory isoprenoid intermediates. Using an in vitro model for MKD, we mimicked the blockade of the cholesterol pathway and evaluated the potential anti-inflammatory effect of Lapaquistat. The results obtained showed anti-inflammatory effects of Lapaquistat in association with a low blockade of the metabolic pathway, while this effect did not remain with a tighter blockade. On these bases, Lapaquistat could be configured as an effective treatment for MKD's mild forms, in which the residual enzymatic activity is only reduced and not almost completely absent as in the severe forms.

A randomized, placebo-controlled experimental medicine study of RIPK1 inhibitor GSK2982772 in patients with moderate to severe rheumatoid arthritis.

BACKGROUND: Receptor-interacting protein kinase 1 (RIPK1) is a key mediator of inflammation through cell death and proinflammatory cytokine production. This multicenter, randomized, double-blind (sponsor-unblinded), placebo-controlled, experimental medicine study evaluated the safety, pharmacokinetics (PK), and preliminary efficacy of GSK2982772, a RIPK1 inhibitor, in moderate to severe rheumatoid arthritis (RA). METHODS: Patients with moderate to severe RA who had received ≥12 weeks' stable-dose conventional synthetic disease-modifying antirheumatic drug (csDMARD) therapy were randomized (2:1) to GSK2982772 60 mg or placebo orally 2 or 3 times daily for 84 days. Safety, PK, disease activity, joint damage, and pharmacodynamic (PD) biomarkers were assessed at days 43 and 85. RESULTS: A total of 52 patients were randomized (placebo, 18; GSK2982772, 34). Adverse events (AEs) were reported in 13 (72%) in patients in the placebo group (n = 3 b.i.d; n = 10 t.i.d.) and 20 (61%) in the GSK2982772 group (n = 3 b.i.d; n = 17 t.i.d.). All treatment-related AEs were mild/moderate, except one severe case of alopecia areata at day 49 and retinal vein thrombosis at day 66 (which led to withdrawal from the study) in patients receiving GSK2982772 t.i.d. Disease Activity Score in 28 Joints-C-reactive protein (DAS28-CRP) scores, ACR20/50/70 response, and rates of low disease activity and remission were similar between placebo and GSK2982772 arms. CONCLUSIONS: These results suggest that inhibition of RIPK1 activity at the GSK2982772 exposure levels evaluated do not translate into meaningful clinical improvement of RA. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT02858492 . Registered 8 August 2016.

Phase I Basket Study of Taselisib, an Isoform-Selective PI3K Inhibitor, in Patients with PIK3CA-Mutant Cancers.

PURPOSE: Somatic mutations in phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA), which encodes the p110α catalytic subunit of PI3K, are found in multiple human cancers. While recurrent mutations in PIK3CA helical, regulatory, and kinase domains lead to constitutive PI3K pathway activation, other mutations remain uncharacterized. To further evaluate their clinical actionability, we designed a basket study for patients with PIK3CA-mutant cancers with the isoform-specific PI3K inhibitor taselisib. PATIENTS AND METHODS: Patients were enrolled on the basis of local PIK3CA mutation testing into one of 11 histology-specific cohorts and treated with taselisib at 6 or 4 mg daily until progression. Tumor DNA from baseline and progression (when available) was sequenced using a next-generation sequencing panel. Exploratory analyses correlating genomic alterations with treatment outcomes were performed. RESULTS: A total of 166 patients with PIK3CA-mutant cancers were enrolled. The confirmed response rate was 9%. Activity varied by tumor type and mutant allele, with confirmed responses observed in head and neck squamous (15.4%), cervical (10%), and other cancers, plus in tumors containing helical domain mutations. Genomic analyses identified mutations potentially associated with resistance to PI3K inhibition upfront (TP53 and PTEN) and postprogression through reactivation of the PI3K pathway (PTEN, STK11, and PIK3R1). Higher rates of dose modification occurred at higher doses of taselisib, indicating a narrow therapeutic index. CONCLUSIONS: Taselisib had limited activity in the tumor types tested and is no longer in development. This genome-driven study improves understanding of the activity, limitations, and resistance mechanisms of using PI3K inhibitors as monotherapy to target PIK3CA-mutant tumors.

RIPK1: A rising star in inflammatory and neoplastic skin diseases.

Skin diseases bring great psychological and physical impacts on patients, however, a considerable number of skin diseases still lack effective treatments, such as psoriasis, systemic lupus erythematosus, melanoma and so on. Receptor-interacting serine threonine kinase 1 (RIPK1) plays an important role in cell death, especially necroptosis, associated with inflammation and tumor. As many molecules modulate the ubiquitination of RIPK1, disruption of this checkpoint can lead to skin diseases, which can be ameliorated by RIPK1 inhibitors. This review will focus on the molecular mechanism of RIPK1 activation in inflammation as well as the current knowledges on the contribution of RIPK1 in skin diseases.

Response to Inhibition of Receptor-Interacting Protein Kinase 1 (RIPK1) in Active Plaque Psoriasis: A Randomized Placebo-Controlled Study.

Receptor-interacting protein kinase 1 (RIPK1), a regulator of inflammation and cell death, is a potential therapeutic target in immune-mediated inflammatory diseases (IMIDs). The objective of this phase IIa multicenter, randomized, double-blind, placebo-controlled study was to evaluate safety, tolerability pharmacokinetics, pharmacodynamics, and preliminary efficacy of GSK2982772, a RIPK1 inhibitor, in plaque-type psoriasis. Psoriasis patients (N = 65) were randomized to 60 mg twice daily (b.i.d.) or three times daily (t.i.d.), or placebo for 84 days. Most adverse events (AEs) were mild with no severe drug-related AEs reported. Plaque Lesion Severity Sum improved with b.i.d. treatment compared with placebo; interpretation of t.i.d. treatment results was complicated by a high placebo response. Reductions in epidermal thickness and infiltration by CD3+ T cells in the epidermis and dermis were observed compared with placebo. Results support the rationale for additional studies on RIPK1 inhibition in IMIDs.

Predictive and Pharmacodynamic Biomarkers of Response to the Phosphatidylinositol 3-Kinase Inhibitor Taselisib in Breast Cancer Preclinical Models.

The PI3K signaling pathway serves as a central node in regulating cell survival, proliferation, and metabolism. PIK3CA, the gene encoding the PI3K catalytic subunit p110-alpha, is commonly altered in breast cancer resulting in the constitutive activation of the PI3K pathway. Using an unbiased cell line screening approach, we tested the sensitivity of breast cancer cell lines to taselisib, a potent PI3K inhibitor, and correlated sensitivity with key biomarkers (PIK3CA, HER2, PTEN, and ESR1). We further assessed how taselisib modulates downstream signaling in the different genomic backgrounds that occur within breast cancer. We found that sensitivity to taselisib correlated with the presence of PIK3CA mutations, but was independent of HER2 status. We further showed that HER2-amplified/PIK3CA wild-type cell lines are not as sensitive to taselisib when compared with HER2-amplified/PIK3CA-mutant cell lines. In a PIK3CA-mutant/PTEN null background, PI3K downstream signaling rebounded in the presence of taselisib correlating with decreased sensitivity at later time points. Finally, we observed that PIK3CA mutations cooccurred with mutations in the estrogen receptor (ER; ESR1) in metastatic tumors from patients with ER+ breast cancer. However, the cooccurrence of an ESR1 mutation with a PIK3CA mutation did not affect response to taselisib in a single agent setting or in combination with fulvestrant. In summary, these data suggest that development of taselisib in breast cancer should occur in a PIK3CA-mutant setting with cotreatments determined by the specific subtypes under investigation.

RIPK1 inhibitor ameliorates colitis by directly maintaining intestinal barrier homeostasis and regulating following IECs-immuno crosstalk.

BACKGROUND: The receptor-interacting protein kinase 1 (RIPK1) has emerged as a key upstream regulator that controls the inflammatory response via its kinase-dependent and independent functions, which makes it an attractive target for developing new drugs against inflammation-related diseases. Growing evidences illustrate that RIPK1 is certainly associated with pathogenesis of multiple tissue-damage diseases. However, what are intricate regulatory codes of RIPK1 inhibitor in diseases is still obscure. METHODS: We used DSS-induced colitis model in vivo to study the therapeutic effects and the mechanisms of RIPK1 inhibitor. We next characterized the barrier function and the interaction between intestinal epithelial cells (IECs) and immunocytes both in vivo and in vitro. As a candidate in clinical study, GSK2982772 is the most well-developed drug of RIPK1 inhibitors, and we chose it as our study object. RESULTS: We demonstrated that RIPK1 inhibitor could ameliorate the intestinal barrier injury by reducing tight junctions' disruption and accompanying oxidative stress. Moreover, the release of chemokines and adhesion molecules from damaged IECs was suppressed by RIPK1 inhibitor treatment. And these protective effects were not only dependent on the suppression of necroptosis but also on the compromised activity of NF-κB. Taken together, RIPK1 inhibitor exerts suppressive function in intestinal inflammatory response possibly via protecting the intestinal epithelial barrier and maintaining the homeostasis of immune microenvironments. Eventually, the positive feedback immune response which triggered progressive epithelial cells injury could be restrained.

SWOG S1400B (NCT02785913), a Phase II Study of GDC-0032 (Taselisib) for Previously Treated PI3K-Positive Patients with Stage IV Squamous Cell Lung Cancer (Lung-MAP Sub-Study).

BACKGROUND: S1400B is a biomarker-driven Lung-MAP substudy evaluating the phosphatidylinositol 3-kinase (PI3K) inhibitor taselisib (GDC-0032) in patients with PI3K pathway-activated squamous NSCLC (sqNSCLC). METHODS: Eligible patients had tumoral phosphatidylinositol-4,5-biphosphate 3 kinase catalytic subunit alpha (PIK3CA) alterations by next-generation sequencing and disease progression after at least one line of platinum-based therapy. Patients received 4-mg taselisib orally daily. The primary analysis population (PAP) was a subset of patients having substitution mutations believed to be associated with clinical benefit of PI3K inhibitors. Primary endpoint was response by Response Evaluation Criteria in Solid Tumors version 1.1; secondary endpoints included progression-free survival, overall survival and duration of response. RESULTS: Twenty-six patients treated with taselisib comprised the full evaluable population (FEP); 21 patients comprised the PAP. Median age for patients in the FEP was 68 years (range: 53-83 years), 19 were male (73%). The study was closed for futility at interim analysis with one responder in the PAP (5% response rate, 95% confidence interval [CI]: 0%-24%). Two possibly treatment-related deaths (one respiratory failure, one cardiac arrest) were observed; one patient had grades 4 and 11 had grade 3 adverse events. Median progression-free survival and overall survival in the PAP group were 2.9 months (95% CI: 1.8-4.0 mo) and 5.9 months (95% CI: 4.2-7.8 mo), respectively. These numbers were nearly the same in the FEP. CONCLUSIONS: Study S1400B evaluating taselisib in PIK3CA-altered sqNSCLC failed to meet its primary endpoint and was closed after an interim futility analysis. The trial is unique in cataloguing the diversity of PIK3CA mutations in sqNSCLC.

Regulated necrosis in kidney ischemia-reperfusion injury.

Ischemia-reperfusion injury (IRI) is the outcome of an inflammatory process that is triggered when an organ undergoes a transient reduction or cessation of blood flow, followed by re-establishment of perfusion. In the clinical setting, IRI contributes to significant acute kidney injury, patient morbidity and mortality, and adverse outcomes in transplantation. Tubular cell death by necrosis and apoptosis is a central feature of renal IRI. Recent research has challenged traditional views of cell death by identifying new pathways in which cells die in a regulated manner but with the morphologic features of necrosis. This regulated necrosis (RN) takes several forms, with necroptosis and ferroptosis being the best described. The precise mechanisms and relationships between the RN pathways in renal IRI are currently the subject of active research. The common endpoint of RN is cell membrane rupture, resulting in the release of cytosolic components with subsequent inflammation and activation of the immune system. We review the evidence and mechanisms of RN in the kidney following renal IRI, and discuss the use of small molecule inhibitors and genetically modified mice to better understand this process and guide potentially novel therapeutic interventions.

Structure-activity relationships, biological evaluation and structural studies of novel pyrrolonaphthoxazepines as antitumor agents.

Microtubule-targeting agents (MTAs) are a class of clinically successful anti-cancer drugs. The emergence of multidrug resistance to MTAs imposes the need for developing new MTAs endowed with diverse mechanistic properties. Benzoxazepines were recently identified as a novel class of MTAs. These anticancer agents were thoroughly characterized for their antitumor activity, although, their exact mechanism of action remained elusive. Combining chemical, biochemical, cellular, bioinformatics and structural efforts we developed improved pyrrolonaphthoxazepines antitumor agents and their mode of action at the molecular level was elucidated. Compound 6j, one of the most potent analogues, was confirmed by X-ray as a colchicine-site MTA. A comprehensive structural investigation was performed for a complete elucidation of the structure-activity relationships. Selected pyrrolonaphthoxazepines were evaluated for their effects on cell cycle, apoptosis and differentiation in a variety of cancer cells, including multidrug resistant cell lines. Our results define compound 6j as a potentially useful optimized hit for the development of effective compounds for treating drug-resistant tumors.

Proto-oncogenes in a eukaryotic unicellular organism play essential roles in plasmodial growth in host cells.

BACKGROUND: The eukaryotic unicellular protist Plasmodiophora brassicae is an endocellular parasite of cruciferous plants. In host cortical cells, this protist develops a unicellular structure that is termed the plasmodium. The plasmodium is actually a multinucleated cell, which subsequently splits and forms resting spores. The mechanism for the growth of this endocellular parasite in host cell is unclear. RESULTS: Here, combining de novo genome sequence and transcriptome analysis of strain ZJ-1, we identified top five significant enriched KEGG pathways of differentially expressed genes (DEGs), namely translation, cell growth and death, cell communication, cell motility and cancers. We detected 171 proto-oncogenes from the genome of P. brassicae that were implicated in cancer-related pathways, of which 46 were differential expression genes. Three predicted proto-oncogenes (Pb-Raf1, Pb-Raf2, and Pb-MYB), which showed homology to the human proto-oncogenes Raf and MYB, were specifically activated during the plasmodial growth in host cortical cells, demonstrating their involvement in the multinucleate development stage of the unicellular protist organism. Gene networks involved in the tumorigenic-related signaling transduction pathways and the activation of 12 core genes were identified. Inhibition of phosphoinositol-3-kinase relieved the clubroot symptom and significantly suppressed the development process of plasmodia. CONCLUSIONS: Proto-oncogene-related regulatory mechanisms play an important role in the plasmodial growth of P. brassicae.

IGF1R upregulation confers resistance to isoform-specific inhibitors of PI3K in PIK3CA-driven ovarian cancer.

Genomic alterations (GA) in PIK3CA leads to the hyper-activation of the phosphatidylinositol-4, 5-bisphosphate 3-kinase (PI3K) pathway in more than 20% of ovarian cancer (OC) patients. Therefore, PI3K therapies are under clinical evaluation for this subset of patients. Evidently, in clinical trials testing the efficacy of isoform-specific inhibitors of PI3K (PI3Ki), patients having a stable disease eventually relapse, as tumors become resistant to treatment. Hence, there is an urgent clinical need to develop new therapeutic combinations to improve the efficacy of PI3Ki in PIK3CA-driven OC patients. Here we identified the molecular mechanism that limits the efficacy of the beta-sparing PI3Ki, Taselisib (GDC0032), in PIK3CA-mutated OC cell lines (IGROV1 and OAW42) that acquired resistance to GDC0032. By comparing the molecular profile of GDC0032-sensitve and -resistant OC cell lines, we found that AKT/mTOR inhibition is required for GDC0032 efficacy. In resistant cells, the sustained activation of AKT/mTOR was regulated by the upregulation of the insulin growth factor 1 receptor (IGF1R). Knockdown of IGF1R re-sensitized cells to GDC0032 in vitro, and the combination of AEW541, an IGF1R inhibitor, with GDC0032 exhibited potent anti-tumor activity in vitro and in vivo. We further demonstrated that IGF1R regulates tumor cell proliferation in IGROV1 cells, whereas in OAW42, it determines autophagy as well. Overall, our findings suggest that the dual inhibition of PI3K and IGF1R may be considered as a new therapeutic strategy in PIK3CA-driven OC.

Combined inhibition of MEK and PI3K pathways overcomes acquired resistance to EGFR-TKIs in non-small cell lung cancer.

Compensatory activation of the signal transduction pathways is one of the major obstacles for the targeted therapy of non-small cell lung cancer (NSCLC). Herein, we present the therapeutic strategy of combined targeted therapy against the MEK and phosphoinositide-3 kinase (PI3K) pathways for acquired resistance to epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) in NSCLC. We investigated the efficacy of combined trametinib plus taselisib therapy using experimentally established EGFR-TKI-resistant NSCLC cell lines. The results showed that the feedback loop between MEK/ERK and PI3K/AKT pathways had developed in several resistant cell lines, which caused the resistance to single-agent treatment with either inhibitor alone. Meanwhile, the combined therapy successfully regulated the compensatory activation of the key intracellular signals and synergistically inhibited the cell growth of those cells in vitro and in vivo. The resistance mechanisms for which the dual kinase inhibitor therapy proved effective included (MET) mesenchymal-epithelial transition factor amplification, induction of epithelial-to-mesenchymal transition (EMT) and EGFR T790M mutation. In further analysis, the combination therapy induced the phosphorylation of p38 MAPK signaling, leading to the activation of apoptosis cascade. Additionally, long-term treatment with the combination therapy induced the conversion from EMT to mesenchymal-to-epithelial transition in the resistant cell line harboring EMT features, restoring the sensitivity to EGFR-TKI. In conclusion, our results indicate that the combined therapy using MEK and PI3K inhibitors is a potent therapeutic strategy for NSCLC with the acquired resistance to EGFR-TKIs.

Phase I study of taselisib in Japanese patients with advanced solid tumors or hormone receptor-positive advanced breast cancer.

Taselisib is a potent and selective phosphatidylinositide 3-kinase (PI3K) inhibitor. The present article reports the first study of taselisib administration in Japanese patients. The aim of this 2-stage, phase I, multicenter, open-label, dose-escalation study was to evaluate the safety, pharmacokinetics, and preliminary efficacy of taselisib as monotherapy in Japanese patients with advanced solid tumors (stage 1), and as part of combination therapy in Japanese patients with hormone receptor (HR)-positive locally advanced or recurrent breast cancer (stage 2). In stage 1, oral taselisib tablets 2, 4, and 6 mg/d were given in 28-day cycles. In stage 2, successive cohorts of patients received oral taselisib tablets (2 or 4 mg/d) with i.m. fulvestrant 500 mg. Nine and 6 patients were enrolled in stage 1 and stage 2, respectively. Taselisib was well tolerated. No dose-limiting toxicities were experienced in any cohort of patients and no deaths were observed. The most common treatment-related adverse events in stage 1 and stage 2, respectively, were rash (55.6%, 66.7%), diarrhea (44.4%, 66.7%), and stomatitis (44.4%, 66.7%). Taselisib was rapidly absorbed after dosage; its half-life was 12.9-32.0 hours in stage 1 and 16.1-26.5 hours in stage 2. Two patients achieved partial response (PR), 5 patients had stable disease (SD) and 2 patients had progressive disease (PD) in stage 1, and 1 patient had PR and 3 patients had SD in stage 2. All patients with PR were positive for PIK3CA gene mutations. These preliminary data suggest that taselisib may be effective in patients with PIK3CA-mutated solid tumors or HR-positive advanced breast cancer.

Repositioning of Tak-475 In Mevalonate Kinase Disease: Translating Theory Into Practice.

BACKGROUND: Mevalonate Kinase Deficiency (MKD, OMIM #610377) is a rare autosomal recessive metabolic and inflammatory disease. In MKD, defective function of the enzyme mevalonate kinase, due to a mutation in the MVK gene, leads to the shortage of mevalonate- derived intermediates, which results in unbalanced prenylation of proteins and altered metabolism of sterols. These defects lead to a complex multisystem inflammatory and metabolic syndrome. OBJECTIVE: Although biologic therapies aimed at blocking the inflammatory cytokine interleukin- 1 can significantly reduce inflammation, they cannot completely control the clinical symptoms that affect the nervous system. For this reason, MKD can still be considered an orphan drug disease. The availability of MKD models reproducing the MKD-systematic inflammation, is crucial to improve the knowledge on its pathogenesis, which is still unknown. New therapies are also required in order to improve pateints' conditions and their quality of life. METHODS: MKD-cellular models can be obtained by biochemical inhibition of mevalonatederived isoprenoids. Of note, these cells present an exaggerated response to inflammatory stimuli that can be reduced by treatment with zaragozic acid, an inhibitor of squalene synthase, thus increasing the availability of isoprenoids intermediates upstream the enzymatic block. RESULTS: A similar action might be obtained by lapaquistat acetate (TAK-475, Takeda), a drug that underwent extensive clinical trials as a cholesterol lowering agent 10 years ago, with a good safety profile. CONCLUSIONS: Here we describe the preclinical evidence supporting the possible repositioning of TAK-475 from its originally intended use to the treatment of MKD and discuss its potential to modulate the mevalonate pathway in inflammatory diseases.

Eleclazine exhibits enhanced selectivity for long QT syndrome type 3-associated late Na+ current.

BACKGROUND: Eleclazine (GS-6615) is a sodium channel blocker designed to improve the selectivity for cardiac late Na+ current (INa) over peak INa. OBJECTIVES: The goals of this study were to investigate the inhibition of late INa by eleclazine using a sample of long QT syndrome type 3 (LQT3) and overlap LQT3/Brugada syndrome mutant channels; to compare the apparent binding rates for eleclazine with those for other class 1 antiarrhythmic agents; and to investigate the binding site. METHODS: Wild-type human cardiac voltage-gated sodium channel (hNaV1.5) and 21 previously reported variants were studied using patch clamp recordings from a heterologous expression system. RESULTS: Eleclazine inhibited anemone toxin II-enhanced late INa from wild-type hNaV1.5 with a drug concentration that causes 50% block of 0.62 ± 0.12 µM (84-fold selectivity over peak INa). The drug concentration that causes 50% block of eleclazine to inhibit the enhanced late INa from LQT3 mutant channels ranged from 0.33 to 1.7 µM. At predicted therapeutic concentrations, eleclazine and ranolazine inhibited peak INa to a similar degree as assessed with 4 overlap LQT3/Brugada syndrome mutations. Eleclazine was found to interact with hNaV1.5 significantly faster than ranolazine and 6 other class 1 antiarrhythmic agents. Engineered mutations (F1760A/Y1767A) located within the local anesthetic binding site decreased the inhibition of late INa and peak INa by eleclazine. CONCLUSION: At predicted therapeutic concentrations, eleclazine elicits potent inhibition of late INa across a cohort of NaV1.5 mutant channels. These properties are consistent with a class 1b antiarrhythmic agent that associates with unusually rapid binding/unbinding rates.