The preparation of (4H)-imidazol-4-ones and their application in the total synthesis of natural products

(4H)-Imidazol-4-ones are an important scaffold for a variety of applications, including natural products, medicine, agriculture, and other applications. Over the years, there have been a number of preparations published for the synthesis of imidazol-4-ones. This review discusses the progress made on the synthesis of imidazol-4-ones, and their application towards the total synthesis of a range of imidazol-4-one containing natural products. Emphasis is made on areas of the field that still need progress.

Anticancer applications of allosteric inhibitors of proteasome

e23066

Background: Proteasome as a hub protease of the ubiquitin proteasome pathway is an established anticancer drug target. Several drugs that inhibit proteasome are currently used to successfully treat aggressive blood cancers. These drugs are based on their competition with protein substrates of proteasome. However, efficacy of these drugs toward solid cancers is inadequate. Besides, the side effects and developing drug resistance are increasingly hampering the therapy. Therefore, there is an unmet challenge to develop new types of proteasome targeting compounds that are efficient against solid cancers and utilize other mechanisms to stop proteasome. Here we present a compound with a novel molecular mechanism, potentially bypassing limitations of the available drugs. Methods: We rationally designed and synthesized a series of small molecule “B” compounds, derivatives of a binding domain of seco-rapamycin that noncompetitively interfere with peptidase activities of proteasome. We tested effects of the compounds in vitro on purified proteasome, in cellulo with selected cancer cell lines and in a xenograft mouse model of prostate cancer. Results: We found that compound B1 binds to the catalytic core of proteasome far from the catalytic sites, destabilizes assembly of the 26S proteasome responsible for digest of polyUb substrates and allosterically inhibits its proteolytic activities. Molecularly, B1 impedes the gating mechanism responsible for substrate uptake as found with AFM. Tryptophan fluorescence indicates that B1 changes proteasome fold and the binding mode of competitive inhibitors. B1 substantially decreases viability of selected cancer cell lines and shifts their mechanical phenotype toward noncancerous status. B1 synergizes with bortezomib decreasing the IC50 5-10 fold. In a xenograft hormone resistant prostate cancer model, B1 treatment leads to shrinkage of the tumor size, decreases enumeration of aggressive, EpCAM+ CTCs and shifts the macrophage profile toward predator M1 type. Conclusions: B1 compounds constitute a new class of noncompetitive allosteric inhibitors of proteasome that could be useful to develop to treat aggressive prostate cancers alone or in synergy with competitive inhibitors.

Simultaneous hemodynamic and serological cardiotoxicity monitoring during immunotherapy with trastuzumab

BACKGROUND

Immunotherapy with trastuzumab (Herceptin), a selective HER-2(ErbB2)-antibody, is associated with a certain degree of cardiotoxicity. This study sought to evaluate the immediate hemodynamic response to trastuzumab with real-time CW-Doppler depending on the level of nt-pro-BNP (brain natriuretic peptide) as a possible marker of cardiotoxicity.

METHODS

48 patients with HER-2-positive metastatic breast cancer were continuously measured with CW-Doppler ultrasound for cardiac output (CO) and systemic vascular resistance (SVR) before, during and after drug infusion in combination with nt-pro-BNP before and 10 min after drug infusion. Depending on the nt-pro-BNP-levels <125 pg/ml (group A, n=34, 51+/-11 years) vs. nt-pro-BNP >125 pg/ml (group B, n=14, 63+/-7 years) two groups have been defined.

RESULTS

Trastuzumab therapy did not change nt-pro-BNP immediately before (44+/-29 pg/ml) vs. after the infusion (45+/-32 pg/ml, n.s.) in the low-level as in the high level nt-pro-BNP group (231+/-356 pg/ml prior and 240+/-377 pg/ml, n.s.). Cardiac output remained stable during trastuzumab infusion, however cardiac output was significantly increased following the end of the infusion stronger in the high-level nt-pro-BNP group. Systemic vascular resistance prior to the trastuzumab infusion was higher in the high-level nt-pro-BNP group with significant decrement during and after the infusion.

CONCLUSION

Combining real-time CW-Doppler ultrasound and nt-pro-BNP monitoring is feasible to monitor the immediate hemodynamic changes during and after trastuzumab infusion.

Combined NT-pro-BNP and CW-Doppler ultrasound cardiac output monitoring (USCOM) in epirubicin and liposomal doxorubicin therapy

BACKGROUND

Chemotherapy with epirubicin is approved in women with breast cancer and is associated with a certain degree of cardiotoxicity.

HYPOTHESIS

Epirubicin changes stroke volume, cardiac output and systemic vascular resistance, while liposomal doxorubicin does not.

METHODS

75 patients with HER-2-positive metastatic breast cancer were continuously measured with CW-Doppler ultrasound for stroke volume (SV), cardiac output (CO), and systemic vascular resistance (SVR) before, during and after drug infusion in combination with NT-pro-BNP before and 10 min after drug infusion.

RESULTS

Epirubicin infusion increased stroke volume significantly in low-level NT-pro-BNP (62+/-23 ml vs. 74+/-29 ml, p=0.004) and high-level NT-pro-BNP (48+/-5 ml vs. 64+/-20 ml, p=0.131), while liposomal doxorubicin infusion increased stroke volume significantly in low-level NT-pro-BNP (54+/-16 ml vs. 67+/-22 ml, p=0.001) and high-level NT-pro-BNP (65+/-22 ml vs. 82+/-27 ml, p=0.001). Cardiac output was significantly increased in epirubicin (p=0.004) by 20% (NT-pro-BNP<125 pg/ml) and not significantly 38% (NT-pro-BNP>125 pg/ml; p=0.144), while in liposomal doxorubicin cardiac output was significantly increased by 23% (NT-pro-BNP<125 pg/ml; p=0.023) and 33% (NT-pro-BNP>125 pg/ml; p=0.001). In liposomal doxorubicin cardiac index was significantly increased by 26% (NT-pro-BNP<125 pg/ml; p=0.021) and 33% (NT-pro-BNP>125 pg/ml; p=0.0001). SVR was significantly reduced during and after epirubicin therapy.

CONCLUSION

Using the CW-Doppler USCOM a different hemodynamic response to epirubicin vs. liposomal doxorubicin is evident. Epirubicin leads to a significant upregulation of stroke volume and cardiac output, which is even more pronounced in the high-level NT-pro-BNP group, while liposomal doxorubicin does not change immediate hemodynamics. No deterioration of cardiac function using the real-time CW-Doppler ultrasound USCOM or an increase in NT-pro-BNP levels was evident during epirubicin or liposomal doxorubicin therapy.

["Good advice is precious." The second opinion from the point of view of an interdisciplinary cancer therapy center]

BACKGROUND AND OBJECTIVE

The setting up of an interdisciplinary tumor treatment center together with a "tumor board" has resulted in early specialty-bridging assessment and therapeutic decisions of cancers, some of them complex, in hospitalized patients with visceral tumors. It was the aim of this study to compare the use and value of the decisions of the tumor board ("second opinion") with those of the original assessment made elsewhere after primary surgical treatment.

PATIENTS AND METHODS

Information on the tumor board's database, recorded explicitly as "external comments" or "second opinion" were accessed. The data were then classified according to organs or organ systems and further divided into those cases in which the primary tumor had not been treated, those with tumor recurrence and those with metastases or recurrence of metastases.

RESULTS

8298 cases were evaluated during a five-year period. There were 373 "second opinions" (4.5%), most of the referrals relating to tumors of the upper gastrointestinal tract, corresponding to the focus of our institution. Previously untreated primary tumors amounted to 53.6% of cases, local recurrences in 14.7% and initial evidence of metastases of a visceral tumor in 9.9%. In 21.7% progression of a known metastasizing tumor was the main reason for requesting a second opinion. The second opinion agreed with the external decision for surgery alone in 16.4% of all enquiries. Minor modifications of the external therapeutic decisions were recommended in 5.9% of referred cases, while in 47.2% major changes were recommended. 28,7% of enquiries could not be evaluated because essential data were not available.

CONCLUSIONS

Requests for a second opinion in the treatment of visceral tumors are still rare in Germany. Good and current findings are requisites for giving a reliable second opinion. In fewer than a fifth of cases was there agreement with regard to a primarily surgical intervention. The concept of multimodal forms of treatment are usually given priority, which underlines the need for establishing interdisciplinary advisory panels.

[Lung function, gas exchange and regulation of ventilation in patients with portocaval encephalopathy (author's transl)]

In 17 patients, breathing room air and pure oxygen, with histologically proven cirrhosis of the liver and portocaval encephalopathy grade I, static and dynamic lung volumes, closing capacity and arterial blood gases were determined. Furthermore, CO2, response curves were provided and mouth occlusion pressure measurements were carried out. The residual volume was found to be increased (130 +/- 8% of predicted) which resulted in decreased vital capacity (79 +/- 2% of predicted) with total lung capacity being normal (94 +/- 2% of predicted). Closing capacity was increased to 134 +/- 5% of the predicted value. Gas exchange for oxygen was impaired (AaDO2 = 262 +/- 30% of predicted). Arterial PO2, however, was within normal range PaO2 = 84 +/- 3.6 mm Hg) due to hyperventilation (PaCO2 = 28.1 +/- 0.8 mm Hg). Hypoxic ventilatory stimulation could be excluded because inspiration of pure oxygen caused no change of PaCO2 (PaCO2 = 27.3 + 0.7 mm Hg and PaO2 = 465 + 16.9 mm Hg with FIO2 = 1.0). The slope of the CO2 response curves was normal, the mouth occlusion pressures, however, were higher than the predicted value: up to PaCO2 of 55 mm Hg. The slope of these curves being smaller than predicted. The results show that in patients with portocaval encephalopathy the lung function is disturbed due to premature airway closure with consequently decreased regional ventilation: perfusion ratios and that regulation of ventilation is impaired by a loss of sensitivity for CO2 with high basal output of the respiratory centers not related to CO2.