Trabectedin in soft tissue sarcomas

Extensive Studies on the Synthesis and Characterization of π-Arene Chromium Complexes and Their Performance in SNAr and Suzuki-Miyaura Cross-Coupling Reactions

We report an efficient synthesis of a series of new (η6-arene)Cr(CO)3 complexes via ligand exchange strategy under thermal conditions using chromium hexacarbonyl and readily accessible arene feedstocks. We optimized the previously reported procedures and found that the high excess of arenes usually employed is not required to access the π-arene chromium complexes in high yields. Consequently, the revised procedure simplifies the purification of chromium tricarbonyl complexes bearing arenes with high boiling points. The reaction is amenable to provide (η6-arene)Cr(CO)3 complexes decorated with various functional groups. Notably, the novel and already reported chromium complexes with missing spectroscopic characterization were fully characterized by nuclear magnetic resonance (NMR), infrared (IR) spectroscopies, and high-resolution mass spectrometry (HRMS). Besides, we report the structure of 20 chromium complexes characterized via X-ray crystallography. The potential application of these π-arene chromium complexes has also been exploited toward the selective construction of poly(hetero)aryls possessing a single chromium tricarbonyl unit through SNAr and Suzuki-Miyaura cross-coupling reactions. This work is meant to be a practical guide for the synthesis of π-arene chromium complexes and to fill the gap in their spectroscopic characterization.

Marine-Derived Anticancer Agents Targeting Apoptotic Pathways: Exploring the Depths for Novel Cancer Therapies

Extensive research has been conducted on the isolation and study of bioactive compounds derived from marine sources. Several natural products have demonstrated potential as inducers of apoptosis and are currently under investigation in clinical trials. These marine-derived compounds selectively interact with extrinsic and intrinsic apoptotic pathways using a variety of molecular mechanisms, resulting in cell shrinkage, chromatin condensation, cytoplasmic blebs, apoptotic bodies, and phagocytosis by adjacent parenchymal cells, neoplastic cells, or macrophages. Numerous marine-derived compounds are currently undergoing rigorous examination for their potential application in cancer therapy. This review examines a total of 21 marine-derived compounds, along with their synthetic derivatives, sourced from marine organisms such as sponges, corals, tunicates, mollusks, ascidians, algae, cyanobacteria, fungi, and actinobacteria. These compounds are currently undergoing preclinical and clinical trials to evaluate their potential as apoptosis inducers for the treatment of different types of cancer. This review further examined the compound's properties and mode of action, preclinical investigations, clinical trial studies on single or combination therapy, and the prospective development of marine-derived anticancer therapies.

SAINT: A Phase I/Expanded Phase II Study Using Safe Amounts of Ipilimumab, Nivolumab and Trabectedin as First-Line Treatment of Advanced Soft Tissue Sarcoma

BACKGROUND

This Phase 1/2 study is based on the hypothesis that immune checkpoint inhibitors are more effective when given earlier in the course of the disease for advanced soft tissue sarcoma.

METHODS

Phase I endpoints-maximum tolerated dose in previously treated patients; Phase II endpoints-best response, progression free survival and overall survival and incidence of adverse events in previously untreated patients; Phase I treatments-escalating doses of trabectedin (1.0, 1.2, 1.5 mg/m²) as continuous intravenous infusion over 24 h every 3 weeks, 1 mg/kg of ipilimumab given intravenously every 12 weeks, and 3 mg/kg of nivolumab given intravenously every 2 weeks; Phase II treatments-maximum tolerated dose of trabectedin and defined doses of ipilimumab and nivolumab.

RESULTS

Phase I (n = 9)-the maximum tolerated dose of trabectedin was 1.2 mg/m²; Phase II (n = 79)-6 complete responses, 14 partial responses, 49 stable disease, 25.3% best response rate, 87.3% disease control rate; median progression-free survival, 6.7 months (CI 95%: 4.4-7.9), median overall survival, 24.6 months (CI 95%: 17.0-.); Grade 3/4 therapy-related adverse events (n = 92)-increased ALT (25%), fatigue (8.7%), increased AST (8.7%), decreased neutrophil count (5.4%) and anemia (4.6%).

CONCLUSION

SAINT is a safe and effective first-line treatment for advanced soft tissue sarcoma.

Trabectedin in Cancers: Mechanisms and Clinical Applications

Trabectedin, a tetrahydroisoquinoline alkaloid, is the first marine antineoplastic agent approved with special anticancer mechanisms involving DNA binding, DNA repair pathways, transcription regulation and regulation of the tumor microenvironment. It has favorable clinical applications, especially for the treatment of patients with advanced soft tissue sarcoma, who failed in anthracyclines and ifosfamide therapy or could not receive these agents. Currently, trabectedin monotherapy regimen and regimens of combined therapy with other agents are both widely used for the treatment of malignancies, including soft tissue sarcomas, ovarian cancer, breast cancer, and non-small-cell lung cancer. In this review, we summarized the basic information and some updated knowledge on trabectedin, including its molecular structure, metabolism in various cancers, pharmaceutical mechanisms, clinical applications, drug combination, and adverse reactions, along with prospections on its possibly more optimal use in cancer treatment.

Retracted Article: The synthesis and biological activity of marine alkaloid derivatives and analogues

The ocean is the origin of life, with a unique ecological environment, which has given birth to a wealth of marine organisms. The ocean is an important source of biological resources and tens of thousands of monomeric compounds have been separated from marine organisms using modern separation technology. Most of these monomeric compounds have some kind of biological activity that has attracted extensive attention from researchers. Marine alkaloids are a kind of compound that can be separated from marine organisms. They have complex and special chemical structures, but at the same time, they can show diversity in biological activities. The biological activities of marine alkaloids mainly manifest in the form of anti-tumor, anti-fungus, anti-viral, anti-malaria, and anti-osteoporosis properties. Many marine alkaloids have good medicinal prospects and can possibly be used as anti-tumor, anti-viral, and anti-fungal clinical drugs or as lead compounds. The limited amounts of marine alkaloids that can be obtained by separation, coupled with the high cytotoxicity and low selectivity of these lead compounds, has restricted the clinical research and industrial development of marine alkaloids. Marine alkaloid derivatives and analogues have been obtained via rational drug design and chemical synthesis, to make up for the shortcomings of marine alkaloids; this has become an urgent subject for research and development. This work systematically reviews the recent developments relating to marine alkaloid derivatives and analogues in the field of medical chemistry over the last 10 years (2010-2019). We divide marine alkaloid derivatives and analogues into five types from the point-of-view of biological activity and elaborated on these activities. We also briefly discuss the optimization process, chemical synthesis, biological activity evaluation, and structure-activity relationship (SAR) of each of these compounds. The abundant SAR data provides reasonable approaches for the design and development of new biologically active marine alkaloid derivatives and analogues.

Overall survival and histology-specific subgroup analyses from a phase 3, randomized controlled study of trabectedin or dacarbazine in patients with advanced liposarcoma or leiomyosarcoma

BACKGROUND

We performed a randomized phase 3 study of trabectedin versus dacarbazine in previously-treated patients with liposarcoma/leiomyosarcoma (LPS/LMS).

METHODS

Patients were randomized 2:1 to trabectedin (n = 384) or dacarbazine (n = 193) administered intravenously every 3 weeks. The primary objective was overall survival (OS). Secondary objectives were progression-free survival, objective response rate, safety, and patient-reported outcomes, all previously reported and demonstrating superior disease control with trabectedin. Results of the final OS analysis in preplanned subgroups of patients with LPS/LMS are presented.

RESULTS

At the time of the final OS analysis, 577 patients had been assigned randomly, including 423 (73%) with LMS and 154 (27%) with LPS. The median duration of treatment exposure was higher in the trabectedin arm compared with the dacarbazine arm (4 vs 2 cycles), as was the proportion of patients receiving an extended number of therapy courses (≥6 cycles: 42% vs 22%). This pattern was consistent across histological subgroups: the median number of treatment cycles (4 vs 2 for both subgroups) and proportion of patients with ≥6 treatment cycles (LMS, 43% vs 24%; LPS, 40% vs 16%). Despite improved disease control by trabectedin, no improvement in OS was observed; the final median OS for trabectedin versus dacarbazine was 13.7 versus 13.1 months (P = .49). Sensitivity analyses of OS suggest confounding by post-study anticancer therapies, which were utilized in most patients in both treatment arms (71% vs 69%, respectively).

CONCLUSION

The final OS results demonstrated comparable survival between LPS/LMS patients receiving trabectedin or dacarbazine, which is consistent with the interim analysis results. Both LPS and LMS demonstrated improved disease control with trabectedin.

Microtubule-Targeting 7-Deazahypoxanthines Derived from Marine Alkaloid Rigidins: Exploration of the N3 and N9 Positions and Interaction with Multidrug-Resistance Proteins

Our laboratories have been investigating synthetic analogues of marine alkaloid rigidins that possess promising anticancer activities. These analogues, based on the 7-deazahypoxanthine skeleton, are available in one- or two-step synthetic sequences and exert cytotoxicity by disrupting microtubule dynamics in cancer cells. In the present work we extended the available structure-activity relationship (SAR) data to N3- and N9-substituted derivatives. Although N3 substitution results in loss of activity, the N9-substituted compounds retain nanomolar antiproliferative activities and the anti-tubulin mode of action of the original unsubstituted compounds. Furthermore, our results also demonstrate that multidrug-resistance (MDR) proteins do not confer resistance to both N9-unsubstituted and -substituted compounds. It was found that sublines overexpressing ABCG2, ABCC1, and ABCB1 proteins are as responsive to the rigidin analogues as their parental cell lines. Thus, the study reported herein provides further impetus to investigate the rigidin-inspired 7-deazahypoxanthines as promising anticancer agents.

Innovative approaches to establish and characterize primary cultures: an ex vivo 3D system and the zebrafish model

Patient-derived specimens are an invaluable resource to investigate tumor biology. However, in vivo studies on primary cultures are often limited by the small amount of material available, while conventional in vitro systems might alter the features and behavior that characterize cancer cells. We present our data obtained on primary dedifferentiated liposarcoma cells cultured in a 3D scaffold-based system and injected into a zebrafish model. Primary cells were characterized in vitro for their morphological features, sensitivity to drugs and biomarker expression, and in vivo for their engraftment and invasiveness abilities. The 3D culture showed a higher enrichment in cancer cells than the standard monolayer culture and a better preservation of liposarcoma-associated markers. We also successfully grafted primary cells into zebrafish, showing their local migratory and invasive abilities. Our work provides proof of concept of the ability of 3D cultures to maintain the original phenotype of ex vivo cells, and highlights the potential of the zebrafish model to provide a versatile in vivo system for studies with limited biological material. Such models could be used in translational research studies for biomolecular analyses, drug screenings and tumor aggressiveness assays.

Current classification, treatment options, and new perspectives in the management of adipocytic sarcomas

Sarcomas are a heterogeneous group of mesenchymal tumors arising from soft tissue or bone, with an uncertain etiology and difficult classification. Soft tissue sarcomas (STSs) account for around 1% of all adult cancers. Till date, more than 50 histologic subtypes have been identified. Adipocyte sarcoma or liposarcoma (LPS) is one of the most common STS subtypes, accounting for 15% of all sarcomas, with an incidence of 24% of all extremity STSs and 45% of all retroperitoneal STSs. The new World Health Organization classification system has divided LPS into four different subgroups: atypical lipomatous tumor/well-differentiated LPS, dedifferentiated LPS, myxoid LPS, and pleomorphic LPS. These lesions can develop at any location and exhibit different aggressive potentials reflecting their morphologic diversity and clinical behavior. Patients affected by LPS should be managed in specialized multidisciplinary cancer centers. Whereas surgical resection is the mainstay of treatment for localized disease, the benefits of adjuvant and neoadjuvant chemotherapy are still unclear. Systemic treatment, particularly chemotherapy, is still limited in metastatic disease. Despite the efforts toward a better understanding of the biology of LPS, the outcome of advanced and metastatic patients remains poor. The advent of targeted therapies may lead to an improvement of treatment options and clinical outcomes. A larger patient enrollment into translational and clinical studies will help increase the knowledge of the biological behavior of LPSs, test new drugs, and introduce new methodological studies, that is, on treatment response.

Trabectedin for Soft Tissue Sarcoma: Current Status and Future Perspectives

Trabectedin (ET743, Yondelis^®, manufactured by Baxter Oncology GmbH, Halle/Westfalen, Germany, for Janssen Products, LP, Horsham, PA), derived from the marine ascidian, Ecteinascidia turbinata, is a natural alkaloid with multiple complex mechanisms of action. On 23 October 2015, 15 years after the results of the first Phase 1 clinical trial using trabectedin for chemotherapy-resistant solid malignancies was reported, and 8 years after its approval in Europe, the United States Food and Drug Administration (USFDA) finally approved trabectedin for the treatment of unresectable or metastatic liposarcoma or leiomyosarcoma that has failed a prior anthracycline-containing regimen. Approval was based on the results of a pivotal Phase 3 trial involving a 2:1 randomization of 518 patients (who were further stratified by soft tissue sarcoma subtype), in which a significant improvement in progression-free survival was reported in the trabectedin-treated group vs. the dacarbazine-treated group (p < 0.001). In this trial, the most common adverse reactions were nausea, fatigue, vomiting, constipation, anorexia, diarrhea, peripheral edema, dyspnea, and headache, while the most serious were neutropenic sepsis, rhabdomyolysis, cardiomyopathy, hepatotoxicity, and extravasation leading to tissue necrosis. The most common grade 3–4 adverse events were laboratory abnormalities of myelosuppression in both arms and transient transaminitis in the trabectedin arm. In a recent Phase 2 trial, trabectedin had a similar outcome as doxorubicin when given as a single agent in the first-line setting. Studies are also being conducted to expand the use of trabectedin not only as a first-line cancer drug, but also for a number of other clinical indications, for example, in the case of mesenchymal chondrosarcoma, for which trabectedin has been reported to be exceptionally active. The possibility of combining trabectedin with targeted therapies, immune checkpoint inhibitors or virotherapy would also be an interesting concept. In short, trabectedin is an old new drug with proven potential to impact the lives of patients with soft tissue sarcoma and other solid malignancies.

Funding: Sarcoma Oncology Center, Santa Monica, CA 90405.

Recent advances in isolation, synthesis, and evaluation of bioactivities of bispyrroloquinone alkaloids of marine origin

The ocean continues to provide a plethora of unique scaffolds capable of remarkable biological applications. A large number of pyrroloiminoquinone alkaloids, including discorhabdins, epinardins, batzellines, makaluvamines, and veiutamine, have been isolated from various marine organisms. A class of pyrroloiminoquinone-related alkaloids, known as bispyrroloquinones, is the focus of this review article. This family of marine alkaloids, which contain an aryl substituted bispyrroloquinone ring system, includes three subclasses of alkaloids namely, wakayin, tsitsikammamines A-B, and zyzzyanones A-D. Both wakayin and the tsitsikammamines contain a tetracyclic fused bispyrroloiminoquinone ring system, while zyzzyanones contain a fused tricyclic bispyrroloquinone ring system. The unique chemical structures of these marine natural products and their diverse biological properties, including antifungal and antimicrobial activity, as well as the potent, albeit generally nonspecific and universal cytotoxicities, have attracted great interest of synthetic chemists over the past three decades. Tsitsikammamines, wakayin, and several of their analogs show inhibition of topoisomerases. One additional possible mechanism of anticancer activity of tsitsikammamines analogs that has been discovered recently is through the inhibition of indoleamine 2, 3-dioxygenase, an enzyme involved in tumoral immune resistance. This review discusses the isolation, synthesis, and evaluation of bioactivities of bispyrroloquinone alkaloids and their analogs.

Novel Microtubule-Targeting 7-Deazahypoxanthines Derived from Marine Alkaloid Rigidins with Potent in Vitro and in Vivo Anticancer Activities

Docking studies of tubulin-targeting C2-substituted 7-deazahypoxanthine analogues of marine alkaloid rigidins led to the design and synthesis of compounds containing linear C2-substituents. The C2-alkynyl analogue was found to have double- to single-digit nanomolar antiproliferative IC50 values and showed statistically significant tumor size reduction in a colon cancer mouse model at nontoxic concentrations. These results provide impetus and further guidance for the development of these rigidin analogues as anticancer agents.