Antitumor activity of the PI3K δ-sparing inhibitor MEN1611 in PIK3CA mutated, trastuzumab-resistant HER2 + breast cancer.

PURPOSE: Dysregulation of the PI3K pathway is one of the most common events in breast cancer. Here we investigate the activity of the PI3K inhibitor MEN1611 at both molecular and phenotypic levels by dissecting and comparing its profile and efficacy in HER2 + breast cancer models with other PI3K inhibitors. METHODS: Models with different genetic backgrounds were used to investigate the pharmacological profile of MEN1611 against other PI3K inhibitors. In vitro studies evaluated cell viability, PI3K signaling, and cell death upon treatment with MEN1611. In vivo efficacy of the compound was investigated in cell line- and patient-derived xenografts models. RESULTS: Consistent with its biochemical selectivity, MEN1611 demonstrated lower cytotoxic activity in a p110δ-driven cellular model when compared to taselisib, and higher cytotoxic activity in the p110ß-driven cellular model when compared to alpelisib. Moreover, MEN1611 selectively decreased the p110α protein levels in PIK3CA mutated breast cancer cells in a concentration- and proteasome-dependent manner. In vivo, MEN1611 monotherapy showed significant and durable antitumor activity in several trastuzumab-resistant PIK3CA-mutant HER2 + PDX models. The combination of trastuzumab and MEN1611 significantly improved the efficacy compared to single agent treatment. CONCLUSIONS: The profile of MEN1611 and its antitumoral activity suggest an improved profile as compared to pan-inhibitors, which are limited by a less than ideal safety profile, and isoform selective molecules, which may potentially promote development of resistance mechanisms. The compelling antitumor activity in combination with trastuzumab in HER2 + trastuzumab-resistant, PIK3CA mutated breast cancer models is at the basis of the ongoing B-Precise clinical trial (NCT03767335).

Targeting CD205 with the antibody drug conjugate MEN1309/OBT076 is an active new therapeutic strategy in lymphoma models.

Antibody drug conjugates represent an important class of anti-cancer drugs in both solid tumors and hematological cancers. Here, we report preclinical data on the anti-tumor activity of the first-in-class antibody drug conjugate MEN1309/OBT076 targeting CD205. The study included preclinical in vitro activity screening on a large panel of cell lines, both as single agent and in combination and validation experiments on in vivo models. CD205 was first shown frequently expressed in lymphomas, leukemias and multiple myeloma by immunohistochemistry on tissue microarrays. Anti-tumor activity of MEN1309/OBT076 as single agent was then shown across 42 B-cell lymphoma cell lines with a median IC50 of 200 pM and induction of apoptosis in 25/42 (59.5%) of the cases. The activity appeared highly correlated with its target expression. After in vivo validation as the single agent, the antibody drug conjugate synergized with the BCL2 inhibitor venetoclax, and the anti-CD20 monoclonal antibody rituximab. The first-in-class antibody drug targeting CD205, MEN1309/OBT076, demonstrated strong pre-clinical anti-tumor activity in lymphoma, warranting further investigations as a single agent and in combination.

Benzofused hydroxamic acids: useful fragments for the preparation of histone deacetylase inhibitors. Part 2: 7-fluorobenzothiophenes and benzofurans.

In the search for a new class of histone deacetylase inhibitors, we prepared a series of very simple benzofused hydroxamic acids to find an anchoring fragment of minimal molecular weight: they showed very good ligand efficiencies. Following these findings, classical fragment growing work was performed to increase binding energy and selective cytotoxicity. In the second phase of the work, information from the SARs of the benzothiophene series and data available in literature, we explored the in vitro pharmacological properties of the 6-substituted-7-fluoro-benzothiophene hydroxamates and the 5-susbtituted-benzofuran hydroxamates.

Benzofused hydroxamic acids: useful fragments for the preparation of histone deacetylase inhibitors. Part 1: hit identification.

In the search for a new class of histone deacetylase inhibitors, we prepared a series of simple benzofused hydroxamic acids to find an anchoring fragment of minimal molecular weight. These initial hits, all belonging to the benzothiophene class, showed very good ligand efficiencies. Following these findings, a classical fragment growing approach was performed to increase binding affinity and cytotoxicity.

The activity of a PI3K δ-sparing inhibitor, MEN1611, in non-small cell lung cancer cells with constitutive activation of the PI3K/AKT/mTOR pathway.

Background: Lung cancer remains the leading cause of cancer-related death worldwide. Targeted therapies with tyrosine kinase inhibitors (TKIs) result in improvement in survival for non-small cell lung cancer (NSCLC) with activating mutations of the epidermal growth factor receptor (EGFR). Unfortunately, most patients who initially respond to EGFR-TKI ultimately develop resistance to therapy, resulting in cancer progression and relapse. Combination therapy is today a common strategy for the treatment of tumors to increase the success rate, improve the outcome and survival of patients, and avoid the selection of resistant cancer cells through the activation of compensatory pathways. In NSCLC, the phosphoinositide-3-kinase/protein kinase B (AKT)/mammalian target of rapamycin (mTOR) pathway has been heavily implicated in both tumorigenesis and the progression of disease. Objectives: In this study, we investigated the efficacy of a PI3K δ-sparing inhibitor, MEN1611, in models of NSCLC sensitive and resistant to EGFR inhibitors (erlotinib and gefitinib) with a wild-type PIK3CA gene. Methods: We performed functional, biochemical, and immunohistochemistry studies. Results: We demonstrated good efficacy of MEN1611 in NSCLC devoid of PIK3CA gene mutations but with constitutive activation of the PI3K/AKT pathway and its synergistic effect with gefitinib both in vitro and in vivo. Conclusions: Overall, this preclinical study indicates that the inhibitor could be a candidate for the treatment of NSCLC with an erlotinib/gefitinib-resistant phenotype and constitutive activation of the PI3K/AKT pathway, a phenotype mimicked by our model system.

Synthesis and biological evaluation of rebeccamycin analogues modified at the imide moiety.

Glycosylated indolocarbazoles related to the antibiotic rebeccamycin represent an important class of antitumour drugs. In the course of our structure-activity relationship studies, new rebeccamycin analogues modified at the imide moiety were synthesised. The antiproliferative activity of the compounds was evaluated on three human cancer cell lines, A2780 (ovarian cancer), H460 (lung cancer), and GLC4 (small-cell lung cancer). The in vitro cytotoxicity of compounds 2 and 4, characterised respectively by a 1,3-dioxolan and (1,3-dioxolan-4-yl)methylene groups linked to the imide moiety, was higher than the reference compound, edotecarin. The effect of compound 2 in inducing tumour regression in the A2780 xenograft model was also investigated.

Set-up of a new series of HDAC inhibitors: the 5,11-dihydrodibenzo[b,e]azepin-6-ones as privileged structures.

We report here the strategy used in our research group to find a new class of histone deacetylase (HDAC) inhibitors. A series of 5,11-dihydrodibenzo[b,e]azepine-6-ones alkylated on the amide nitrogen with an alkyl chain bearing an hydroxamic acids moiety at the end, has been designed (based upon the general motif for HDAC inhibitors), synthesized and tested. This allowed us to identify a new series of submicromolar HDAC inhibitors, which showed antiproliferative activity on HCT-116 colon carcinoma cells.

4-N-Hydroxy-4-[1-(sulfonyl)piperidin-4-yl]-butyramides as HDAC inhibitors.

A series of N-substituted 4-alkylpiperidine hydroxamic acids, corresponding to the basic structure of histone deacetylase (HDAC) inhibitors (zinc binding moiety-linker-capping group) has been previously reported by our group. Linker length and aromatic capping group connection were systematically varied to find the optimal geometric parameters. A new series of submicromolar inhibitors was thus identified, which showed antiproliferative activity on HCT-116 colon carcinoma cells. We report here the second part of the strategy used in our research group to find a new class of HDAC inhibitors, namely the SAR study for the compounds bearing a sulfonyl group on the piperidine nitrogen. In the present work, we have considered both sulfonamides and sulfonyl ureas.

Alkyl piperidine and piperazine hydroxamic acids as HDAC inhibitors.

We report here the strategy used in our research group to find a new class of histone deacetylase (HDAC) inhibitors. A series of N-substituted 4-alkylpiperazine and 4-alkylpiperidine hydroxamic acids, corresponding to the basic structure of HDAC inhibitors (zinc binding moiety-linker-capping group) has been designed, prepared, and tested for HDAC inhibition. Linker length and aromatic capping group connection were systematically varied to find the optimal geometric parameters. A new series of submicromolar inhibitors was thus identified, which showed antiproliferative activity on HCT-116 colon carcinoma cells.

Antitumor activity of delimotecan against human metastatic melanoma: pharmacokinetics and molecular determinants.

Delimotecan (MEN 4901/T-0128) is a new cytotoxic prodrug constituted by a camptothecin analog (T-2513) bound to carboxymethyl dextran through a triglycine linker. A significant antitumor activity of delimotecan against human metastatic melanoma xenograft model Me15392 is reported. Dacarbazine, the drug approved for the treatment of metastatic melanoma, was ineffective in this melanoma model. Pharmacokinetic studies, together with the expression analysis of mRNA for enzymes involved in delimotecan metabolism, showed that T-2513 and other cytotoxic metabolites of delimotecan (SN 38 and T-0055) are generated in greater quantities in the tumor tissue than in toxicity target tissues, such as liver, thus accounting for the antitumoral activity. Moreover, we demonstrated that human metastatic melanoma cells are able to phagocytose delimotecan and cleave it to release the cytotoxic moieties T-2513 in the tumoral environment. Further flow cytometric analysis showed a higher recruitment of macrophages in xenografted human metastatic melanoma, when compared with other human tumors. Thus, the antitumoral activity of delimotecan exerted on metastatic melanoma is due to several factors: (i) the ability of melanoma cells to phagocytose and metabolise delimotecan; (ii) the accumulation of delimotecan in tumoral mass; (iii) the recruitment of macrophage cells to the melanoma nodule and (iv) the expression in melanoma cells of a pattern of enzymes that converts delimotecan into cytotoxic metabolites. Based on these results, delimotecan might be exploited as a new anticancer agent for the therapy of metastatic melanoma because of its high efficacy and good selectivity, and therefore clinical trials for this indication are warranted.

MEN1309/OBT076, a First-In-Class Antibody-Drug Conjugate Targeting CD205 in Solid Tumors.

CD205 is a type I transmembrane glycoprotein and is a member of the C-type lectin receptor family. Analysis by mass spectrometry revealed that CD205 was robustly expressed and highly prevalent in a variety of solid malignancies from different histotypes. IHC confirmed the increased expression of CD205 in pancreatic, bladder, and triple-negative breast cancer (TNBC) compared with that in the corresponding normal tissues. Using immunofluorescence microscopy, rapid internalization of the CD205 antigen was observed. These results supported the development of MEN1309/OBT076, a fully humanized CD205-targeting mAb conjugated to DM4, a potent maytansinoid derivate, via a cleavable N-succinimidyl-4-(2-pyridyldithio) butanoate linker. MEN1309/OBT076 was characterized in vitro for target binding affinity, mechanism of action, and cytotoxic activity against a panel of cancer cell lines. MEN1309/OBT076 displayed selective and potent cytotoxic effects against tumor cells exhibiting strong and low to moderate CD205 expression. In vivo, MEN1309/OBT076 showed potent antitumor activity resulting in durable responses and complete tumor regressions in many TNBC, pancreatic, and bladder cancer cell line-derived and patient-derived xenograft models, independent of antigen expression levels. Finally, the pharmacokinetics and pharmacodynamic profile of MEN1309/OBT076 was characterized in pancreatic tumor-bearing mice, demonstrating that the serum level of antibody-drug conjugate (ADC) achieved through dosing was consistent with the kinetics of its antitumor activity. Overall, our data demonstrate that MEN1309/OBT076 is a novel and selective ADC with potent activity against CD205-positive tumors. These data supported the clinical development of MEN1309/OBT076, and further evaluation of this ADC is currently ongoing in the first-in-human SHUTTLE clinical trial.

Normal-weight obese syndrome: early inflammation?

BACKGROUND: In obese subjects, the adipose mass represents an important source of proinflammatory cytokines. We have identified a new syndrome-the normal-weight obese (NWO) syndrome-in women with normal weight and body mass index but whose fat mass is >30% of their total body weight and whose risk of developing obesity-related diseases is likely increased. OBJECTIVE: The aim of the present study was to verify the hypothesis that NWO women are characterized by early inflammation, related to body fat mass, and that their plasma proinflammatory cytokine concentrations are greater than those of nonobese women. DESIGN: Twenty NWO, 20 preobese-obese, and 20 healthy (nonobese), age-matched white Italian women were studied. Anthropometric variables and plasma concentrations of proinflammatory cytokines and cardiovascular disease (CVD) risk factors were measured and compared between groups. RESULTS: Plasma values and body-composition measures were significantly different between the preobese-obese and nonobese women. No significant differences in body weight, laboratory values, or CVD risk factors were found between the NWO and nonobese groups. Compared with concentrations in the NWO women, plasma concentrations of interleukin (IL)-1alpha, IL-1beta, IL-6, IL-8, and TNF-alpha were significantly lower in the nonobese group and were significantly greater in the preobese-obese group. IL-6 and TNF-alpha concentrations were related to fat mass distribution in the NWO women. CONCLUSIONS: The proinflammatory cytokines could be regarded as significant prognostic indicators of the risk of obesity, CVD, and the metabolic syndrome in NWO women.

Sabarubicin (MEN10755)-induced apoptosis is independent from mtDNA in A2780 human ovarian tumor cells.

BACKGROUND: The role of mitochondrial DNA (mtDNA) in anthracycline-induced apoptosis is controversial. Sabarubicin accumulates in the mitochondria of A2780 human ovarian tumor cells. The effects of this new anthracycline on the structure and the functionality of mtDNA, as well as on the apoptosis of mtDNA-depleted cells have been investigated. MATERIALS AND METHODS: Sabarubicin-induced mtDNA cleavage was detected by Southern blotting and mitochondrial mRNA expression was analyzed by real-time PCR. Apoptosis was studied in mtDNA-depleted (theta0) and parental (theta+) A2780 cells detecting nuclear DNA fragmentation using ELISA and cytofluorimetrically using Annexin V/PI staining. Mitochondrial membrane potential was studied using the cyanine dye JC-1. RESULTS: Sabarubicin induced mtDNA cleavage in the A2780 cells, but this damage did not affect mitochondrial mRNA expression. Apoptosis was induced by sabarubicin in theta0 as well as in theta+ cells. CONCLUSION: The results showed that mtDNA did not influence anthracycline-induced apoptosis in A2780 cells.

Involvement of nitric oxide in both central and peripheral haemodynamic effect of D/L-nebivolol and its enantiomers in rats.

The cardiovascular profile of the racemate D/L-nebivolol and its enantiomers administered by intravenous (i.v.) or by intracerebroventricular (i.c.v.) route was investigated in anaesthetized normotensive rats. D/L-Nebivolol (0.1-0.5 mg/kg) induced a dose-related reduction in blood pressure when administered by i.c.v. route. These hypotensive effects were more marked as compared to those achieved by peripheral administration of D/L-nebivolol (0.1-1 mg/kg i.v.). Both enantiomers contributed to the hypotensive effect of D/L-nebivolol by i.c.v. route, while the effects of the drug on blood pressure by i.v. route were due to the d-enantiomer. The bradycardic effect of the racemic form given i.v. was dose-related and, at the highest dose (1 mg/kg), was more pronounced as compared to i.c.v. route. D-Nebivolol was responsible for chronotropic effects by both the i.v. and i.c.v. route, although by i.c.v. route L-nebivolol also induced a reduction in heart rate. The nitric oxide synthase inhibitor N(omega)-nitro-L-arginine methyl ester (L-NAME) administered at 5 mg/kg i.v. bolus + 0.1 mg/kg/min infusion or at 2.5 mg/kg i.c.v. counteracted the effects of D/L-nebivolol (either 1 mg/kg i.v. or 0.5 mg/kg i.c.v.) on blood pressure, while it did not inhibit the cardiovascular changes induced by isoprenaline (300 ng/kg i.v.) or calcitonin gene-related peptide (CGRP; 400 ng/kg i.v.). In addition, i.c.v. effects of D/L-nebivolol on blood pressure and heart rate were not affected by pre-treatment with atropine (2 mg/kg i.v.). The present findings demonstrate that D/L-nebivolol produced haemodynamic changes following both peripheral and central administration; these latter findings are mainly due to its L-enantiomer and these effects involve the L-arginine/nitric oxide pathway.

MicroRNA-130b promotes tumor development and is associated with poor prognosis in colorectal cancer.

MicroRNA-130b (miR-130b) is involved in several biologic processes; its role in colorectal tumorigenesis has not been addressed so far. Herein, we demonstrate that miR-130b up-regulation exhibits clinical relevance as it is linked to advanced colorectal cancers (CRCs), poor patients' prognosis, and molecular features of enhanced epithelial-mesenchymal transition (EMT) and angiogenesis. miR-130b high-expressing cells develop large, dedifferentiated, and vascularized tumors in mouse xenografts, features that are reverted by intratumor injection of a specific antisense RNA. In contrast, injection of the corresponding mimic in mouse xenografts from miR-130b low-expressing cells increases tumor growth and angiogenic potential while reduces the epithelial hallmarks. These biologic effects are reproduced in human CRC cell lines. We identify peroxisome proliferator-activated receptor γ (PPARγ) as an miR-130b direct target in CRC in vitro and in vivo. Notably, the effects of PPARγ gain- and loss-of-function phenocopy those due to miR-130b down-regulation or up-regulation, respectively, underscoring their biologic relevance. Furthermore, we provide mechanistic evidences that most of the miR-130b-dependent effects are due to PPARγ suppression that in turn deregulates PTEN, E-cadherin, Snail, and vascular endothelial growth factor, key mediators of cell proliferation, EMT, and angiogenesis. Since higher levels of miR-130b are found in advanced tumor stages (III-IV), we propose a novel role of the miR-130b-PPARγ axis in fostering the progression toward more invasive CRCs. Detection of onco-miR-130b and its association with PPARγ may be useful as a prognostic biomarker. Its targeting in vivo should be evaluated as a novel effective therapeutic tool against CRC.

SAHA/Vorinostat induces the expression of the CD137 receptor/ligand system and enhances apoptosis mediated by soluble CD137 receptor in a human breast cancer cell line.

HDAC inhibitors (HDACis) represent a class of anticancer agents including suberoylanilide hydroxamic acid (SAHA, Vorinostat), which has shown a strong antitumor effect, both in vitro and in vivo. Induction of apoptotic genes is an important pathway of SAHA cytotoxic mechanism of action and it has been largely described that SAHA induces sensitization of cell death receptor-resistant breast cancer cells to apoptosis. In this study, we investigated the activation of some apoptotic genes which could be responsible for the in vivo antitumor potency of SAHA in a model of human breast cancer. We found that the apoptotic gene pattern induced by SAHA in the MDA-MB-231 cell line involves the upregulation of some molecules belonging to the TNF superfamily. In particular, we demonstrated that the upregulation of the CD137 receptor/ligand system correlates with a synergistic cytotoxic effect when MDA-MB-231 cells are treated with the combination of SAHA and soluble CD137 receptor. To our knowledge, this is the first study to indicate that this member of the TNF superfamily, CD137, is modulated by SAHA treatment in breast cancer cells, suggesting that the combination of SAHA with this TNF-related receptor could be a new therapeutic approach for the treatment of tumors.

Combined antihypertensive and cardioprotective effects of nebivolol and hydrochlorothiazide in spontaneous hypertensive rats.

The antihypertensive and cardioprotective effects of the combination of nebivolol (NEB) and hydrochlorothiazide (HCTZ) in spontaneously hypertensive rats (SHR) were investigated. SHR and age-matched Wistar-Kyoto normotensive rats were randomly assigned to one of six groups: SHR treated with NEB (1 mg/kg/day, intragastric); SHR treated with HCTZ (5 mg/kg/day, intragastric); SHR treated with NEB plus HCTZ (1 + 2.5 mg/kg/day); SHR treated with NEB plus HCTZ (1 + 5 mg/kg/day), along with a SHR and a WKY control group. The effects of NEB and HCTZ on clinical chemistry parameters and on cardiac function and structure were evaluated. NEB and HCTZ in combination had synergistic antihypertensive effects and significantly reduced heart rate and blood pressure compared with monotherapy with either agent. These effects were independent of water intake, urine output and electrolyte excretion. NEB plus HCTZ was associated with reduced oxidative stress in terms of glutathione availability, lower angiotensin I levels as index of plasma renin activity and reduced clearance of urinary sodium compared with HCTZ alone. Cardiac morphometric data and antioxidant parameters indicate that NEB may influence cardiac structure by reducing hypertrophy and by enhancing the availability of endothelial nitric oxide - a unique characteristic of NEB. The authors suggest that a combination of NEB and HCTZ for the treatment of hypertension may be useful for the synergistic characteristics of both drugs.

Maintenance therapy in ovarian cancer: Molecular basis and therapeutic approach.

Ovarian cancer has the highest mortality rate among gynaecological tumours despite the fact that the majority of patients with advanced disease achieve complete remission after first-line surgery and chemotherapy. Unfortunately, disease recurrence occurs in the majority of patients and second-line treatments are not curative. Clearly, the persistence of dormant and drug-resistant cells after front-line treatments results in the inability to cure the disease. The identification of cancer-initiating cells or cancer stem cells as key players in the development of recurrence has opened up a novel field of research aimed at identifying additional innovative therapeutic approaches. Strategies of maintenance therapy to extend the survival of patients have been studied, but to date no overall survival benefit has been detected. Currently, numerous clinical trials have just been completed or are ongoing involving patients achieving a complete clinical response after first-line chemotherapy in order to evaluate the efficacy of different therapeutic approaches in terms of disease-free survival and overall survival. At the 2010 ASCO meeting, the first positive results of a phase III clinical trial in this setting were presented: bevacizumab (15 mg/kg i.v. every 21 days) added to first-line chemotherapy and continued for an additional 15 cycles was found to prolong progression-free survival of 3.8 months in comparison to 6 cycles of chemotherapy alone or only 6 cycles of chemotherapy plus bevacizumab. In addition, positive results were announced for a second phase III trial testing bevacizumab in the same setting, but at half dose. The final assessment of the overall clinical benefit and the approval of bevacizumab in maintenance therapy by regulatory agencies is expected to be positive, as are the final results of abagovomab phase III trial MIMOSA, another antibody-based therapy tested as a maintenance treatment for advanced ovarian cancer patients. Encouraging preliminary results confirming the safety profile and the immunogenic activity of abagovomab were presented at the last ASCO meeting. The final results are expected to be released in the first half of 2011.

Induction of a less aggressive phenotype in human colon carcinoma HCT116 cells by chronic exposure to HDAC inhibitor SAHA.

Histone deacetylase inhibitors (HDACis) are anticancer molecules that epigenetically modulate cell functions. Chronic exposure of HCT116 colon cancer cells to SAHA has been investigated for a better understanding of resistance mechanisms but, surprisingly, a less aggressive tumor phenotype both in vitro and in vivo was obtained after exposure to increasing concentrations of SAHA. Indeed, HCT116/SAHA cells when injected into nude mice showed a reduced engraftment and growth with respect to HCT116 cells. This difference was not observed inoculating the cells into NOD/SCID mice that, differently from nude mice, lack NK activity, thus suggesting the involvement of the native immune response in impairment of HCT116/SAHA cell growth. In agreement with this result, a growing induction of NKG2D ligand expression, MICA and MICB, that are molecular mediators of NK cell killing, was confirmed in HCT116/SAHA chronically exposed to SAHA. A reduced clonogenic efficiency was also observed in HCT116/SAHA with respect to HCT116 cells. Interestingly, even after chronic exposure to SAHA, HCT116/SAHA cells developed only a moderate resistance to SAHA both in vitro and in vivo and they acquired a collateral sensitivity to anthracyclines. These results are of note and probably rely on the fact that, having simultaneously many different targets, HDACis would require many different mutations to display high resistance index. Moreover, to understand the molecular basis of HCT116/SAHA cell phenotype a gene expression profile of cancer genes was evaluated in HCT116 incubated with SAHA for 24 h and in HCT116/SAHA cells to identify selectively regulated genes.

Antiproliferative and differentiating activities of a novel series of histone deacetylase inhibitors.

Histone deacetylases are promising molecular targets for the development of antitumor agents. A novel series of histone deacetylase inhibitors of the hydroxamic acid type were synthesized for structure-activity studies. Thirteen tricyclic dibenzo-diazepine, -oxazepine, and -thiazepine analogues were studied and shown to induce variable degrees of histone H3/H4 and tubulin acetylation in a cellular model of myeloid leukemia sensitive to all-trans retinoic acid (ATRA). Multiparametric correlations between acetylation of the three substrates, tumor cell growth inhibition, and ATRA-dependent cytodifferentiation were performed, providing information on the chemical functionalities governing these activities. For two analogues, antitumor activity in the animal was demonstrated.