From Crypts to Cancer: A Holistic Perspective on Colorectal Carcinogenesis and Therapeutic Strategies

Colorectal cancer (CRC) represents a significant global health burden, with high incidence and mortality rates worldwide. Recent progress in research highlights the distinct clinical and molecular characteristics of colon versus rectal cancers, underscoring tumor location's importance in treatment approaches. This article provides a comprehensive review of our current understanding of CRC epidemiology, risk factors, molecular pathogenesis, and management strategies. We also present the intricate cellular architecture of colonic crypts and their roles in intestinal homeostasis. Colorectal carcinogenesis multistep processes are also described, covering the conventional adenoma-carcinoma sequence, alternative serrated pathways, and the influential Vogelstein model, which proposes sequential APC, KRAS, and TP53 alterations as drivers. The consensus molecular CRC subtypes (CMS1-CMS4) are examined, shedding light on disease heterogeneity and personalized therapy implications.

Paclitaxel and its semi-synthetic derivatives: comprehensive insights into chemical structure, mechanisms of action, and anticancer properties

Cancer is a disease that can cause abnormal cell growth and can spread throughout the body. It is among the most significant causes of death worldwide, resulting in approx. 10 million deaths annually. Many synthetic anticancer drugs are available, but they often come with side effects and can interact negatively with other medications. Additionally, many chemotherapy drugs used for cancer treatment can develop resistance and harm normal cells, leading to dose-limiting side effects. As a result, finding effective cancer treatments and developing new drugs remains a significant challenge. However, plants are a potent source of natural products with the potential for cancer treatment. These biologically active compounds may be the basis for enhanced or less toxic derivatives. Herbal medicines/phytomedicines, or plant-based drugs, are becoming more popular in treating complicated diseases like cancer due to their effectiveness and are a particularly attractive option due to their affordability, availability, and lack of serious side effects. They have broad applicability and therapeutic efficacy, which has spurred scientific research into their potential as anticancer agents. This review focuses on Paclitaxel (PTX), a plant-based drug derived from Taxus sp., and its ability to treat specific tumors. PTX and its derivatives are effective against various cancer cell lines. Researchers can use this detailed information to develop effective and affordable treatments for cancer.

Adverse events of different chemotherapy regimens in the first-line treatment of patients with advanced or metastatic urothelial cancer: A systematic review and network meta-analysis of randomized controlled trials

INTRODUCTION

The present systematic review and network meta-analysis (NMA) of randomized controlled trials (RCTs) aimed to compare the mortality rates related to adverse events (AEs) and discontinuation of treatment due to toxicity as well as all AEs of currently used chemotherapy regimens for first-line therapy of advanced or metastatic urothelial carcinoma of the bladder (UCB).

MATERIAL AND METHODS

The MEDLINE and EMBASE databases were searched for articles published between January 2000 and June 2020 according to the Preferred Reporting Items for Systematic Review and Meta-analysis extension statement for NMA. Eligible studies included RCTs comparing different first-line chemotherapy regimens for treating advanced or metastatic UCB and AEs as outcome measures. A NMA was performed to assess the mortality rates related to AEs and discontinuation of treatment due to toxicity as well as all AEs.

RESULTS

Fourteen trials comprising 2,615 patients met our eligibility criteria and formal NMAs were conducted. Results revealed that gemcitabine plus carboplatin had the lowest likelihood of mortality related to AEs (P score: 0.8079), while larotaxel plus cisplatin and paclitaxel, cisplatin plus gemcitabine had both a lower toxicity rate leading to discontinuation (P score: 0.7295 and P score: 0.7242, respectively). Compared with gemcitabine plus cisplatin (GC), most chemotherapy regimens were associated with a lower likelihood of thrombocytopenia, anemia, and cardiovascular toxicity. In contrast, most chemotherapy regimens compared with GC were associated with a higher likelihood of neutropenia, central (fatigue, neuropathy) and gastrointestinal AEs, infections, as well as renal and pulmonary toxicities.

CONCLUSION

Results of the present study demonstrated that hematological toxicity was the most prevalent AE associated with gemcitabine-containing regimens, while central AEs and febrile neutropenia were more commonly in taxane-containing regimens. GC had the lowest rate of gastrointestinal AEs, infection disorders, and pulmonary toxicities. Cisplatin-containing regimens were associated with a higher rate of renal and cardiovascular toxicity. These differential AEs may help in the detection of the personalized therapy in addition of efficacy data.

Current Therapy for Metastatic Urothelial Carcinoma

Urothelial carcinoma (UC) is a highly lethal malignancy in the metastatic state. Platinum-based chemotherapy regimens have been the backbone treatment for patients with advanced UC in the first-line setting. However, a large subset of patients are suboptimal candidates for these combinations owing to poor renal function and/or other comorbidities. Patients who are unable to tolerate or who progress after frontline platinum chemotherapy face a poor outcome. Recent insights into UC biology and immunology are being translated into new therapies for metastatic UC (mUC) including immune checkpoint inhibitors (ICIs), erdafitinib, a FGFR inhibitor, and antibody drug conjugates (ADC) such enfortumab vedotin.

Nanostructure of Functional Larotaxel Liposomes Decorated with Guanine-Rich Quadruplex Nucleotide-Lipid Derivative for Treatment of Resistant Breast Cancer

Breast cancer is the most common malignant disease in women all over the world and its chemotherapy outcome is restricted by multidrug resistance. Here, a nanostructure by functional larotaxel liposomes decorated with guanine-rich quadruplex nucleotide-lipid derivative for treatment of resistant breast cancer is developed. The studies are performed on the resistant breast cancer cells and the cancer-bearing mice. The nucleotide-lipid derivative (DSPE-PEG₂₀₀₀ -C₆ -GT28nt) is synthesized by introducing a hydrophobic hexyl linkage between GT-28nt (containing 17 guanines and 11 thymidines) and DSPE-PEG₂₀₀₀ -NHS, and is incorporated on the functional larotaxel liposomes for specific binding with nucleolin receptor on the resistant cancer cells. The studies demonstrate that the liposomes had long circulatory effect, targeted capability, and significant anticancer efficacy in resistant cancer-bearing mice. The studies further reveal their action mechanism, consisting of blocking depolymerization of microtubules, arresting cell cycle, blocking JAK-STAT signaling pathway, and inhibiting activity of antiapoptotic proteins. In conclusion, the functional larotaxel liposomes can be used for effective treatment of drug-resistant breast cancer, and this study also offers a novel targeted nanomedicine based on nucleotide-lipid derivative.

Treatment of muscle-invasive and advanced bladder cancer in 2020

Bladder cancer accounts for nearly 170,000 deaths worldwide annually. For over 4 decades, the systemic management of muscle-invasive and advanced bladder cancer has primarily consisted of platinum-based chemotherapy. Over the past 10 years, innovations in sequencing technologies have led to rapid genomic characterization of bladder cancer, deepening our understanding of bladder cancer pathogenesis and exposing potential therapeutic vulnerabilities. On the basis of its high mutational burden, immune checkpoint inhibitors were investigated in advanced bladder cancer, revealing durable responses in a subset of patients. These agents are now approved for several indications and highlight the changing treatment landscape of advanced bladder cancer. In addition, commonly expressed molecular targets were leveraged to develop targeted therapies, such as fibroblast growth factor receptor inhibitors and antibody-drug conjugates. The molecular characterization of bladder cancer and the development of novel therapies also have stimulated investigations into optimizing treatment approaches for muscle-invasive bladder cancer. Herein, the authors review the history of muscle-invasive and advanced bladder cancer management, highlight the important molecular characteristics of bladder cancer, describe the major advances in treatment, and offer future directions for therapeutic development.

Intrinsic and Extrinsic Factors Affecting Microtubule Dynamics in Normal and Cancer Cells

Microtubules (MTs), highly dynamic structures composed of α- and β-tubulin heterodimers, are involved in cell movement and intracellular traffic and are essential for cell division. Within the cell, MTs are not uniform as they can be composed of different tubulin isotypes that are post-translationally modified and interact with different microtubule-associated proteins (MAPs). These diverse intrinsic factors influence the dynamics of MTs. Extrinsic factors such as microtubule-targeting agents (MTAs) can also affect MT dynamics. MTAs can be divided into two main categories: microtubule-stabilizing agents (MSAs) and microtubule-destabilizing agents (MDAs). Thus, the MT skeleton is an important target for anticancer therapy. This review discusses factors that determine the microtubule dynamics in normal and cancer cells and describes microtubule-MTA interactions, highlighting the importance of tubulin isoform diversity and post-translational modifications in MTA responses and the consequences of such a phenomenon, including drug resistance development.

Clinical evidence for the first-line treatment of advanced urothelial carcinoma: Current paradigms and emerging treatment options

BACKGROUND

Patients with advanced urothelial carcinoma (UC) have poor outcomes, with 5-year survival rates of <5% for those with metastatic, stage IV disease. We have reviewed current treatment paradigms and emerging treatment options for these patients.

METHODS

The websites of seven national or international organizations were searched for metastatic UC treatment guidelines. Systematic literature reviews were conducted to identify evidence from randomized controlled trials (RCTs) of chemotherapy for patients with previously untreated, unresectable, stage IV UC. Searches included congress databases and articles published between 1990 and 2018. In order to align with the latest treatment paradigms in first-line advanced UC, a focused literature search was conducted to identify evidence supporting immuno-oncology (IO) agents.

RESULTS

For advanced UC, guidelines universally recommend cisplatin-based chemotherapy as first-line treatment for eligible patients and carboplatin-based regimens for those unfit to receive cisplatin. Despite the evaluation of a number of different cytotoxic regimens over the years, including triplet combinations, survival outcomes have not improved markedly with chemotherapy. Median overall survival with standard of care chemotherapy is ~13 months. Based on the results of single-arm, phase II studies, recent treatment guidelines have included atezolizumab (anti-PD-L1) and pembrolizumab (anti-PD-1) as first-line options for cisplatin-ineligible patients whose tumors express high levels of PD-L1. However, emerging evidence from RCTs of IO agents, including both cisplatin-eligible and cisplatin-ineligible patients, suggest that survival times exceeding 20 months are possible.

CONCLUSIONS

After having reached a plateau with chemotherapy, the treatment landscape for advanced UC is evolving. Survival outcomes for patients with advanced UC are improving with treatment modalities involving IO agents.

Systemic treatment for advanced urothelial cancer: an update on recent clinical trials and current treatment options

After cisplatin-based chemotherapy became the standard treatment for metastatic urothelial cancer (mUC), very little progress has been made in the treatment landscape of this condition until recently. With increased knowledge about the molecular biology of mUC and advances in the field of cancer immunobiology, there has been an explosion in the number of clinical trials for mUC, and systemic treatment of mUC is rapidly changing. Despite the availability of several novel therapeutic agents, cisplatin-based cytotoxic chemotherapy remains the standard, first-line treatment option. Immune checkpoint inhibitors (ICIs), including programmed death-1 and programmed death ligand-1 inhibitors, are preferred second-line treatment options that are also used in first-line cisplatin-ineligible settings. For patients with actionable fibroblast growth factor receptor 2 (FGFR2) or FGFR3 genomic alterations, erdafitinib can be considered after platinum-based treatment. Enfortumab vedotin, a monoclonal antibody targeting nectin-4 conjugated to monomethyl auristatin E, has been approved for patients who do not respond to both cytotoxic chemotherapy and ICIs. In this review, we address the clinical trial data that have established the current standard treatments and ongoing clinical trials of various agents with different mechanisms as well as provide a brief overview of current practice guidelines and recommendations in patients with mUC.

Microtubule-targeting agents and their impact on cancer treatment

Microtubule-targeting agents (MTAs) constitute a diverse group of chemical compounds that bind to microtubules and affect their properties and function. Disruption of microtubules induces various cellular responses often leading to cell cycle arrest or cell death, the most common effect of MTAs. MTAs have found a plethora of practical applications in weed control, as fungicides and antiparasitics, and particularly in cancer treatment. Here we summarize the current knowledge of MTAs, the mechanisms of action and their role in cancer treatment. We further outline the potential use of MTAs in anti-metastatic therapy based on inhibition of cancer cell migration and invasiveness. The two main problems associated with cancer therapy by MTAs are high systemic toxicity and development of resistance. Toxic side effects of MTAs can be, at least partly, eliminated by conjugation of the drugs with various carriers. Moreover, some of the novel MTAs overcome the resistance mediated by both multidrug resistance transporters as well as overexpression of specific β-tubulin types. In anti-metastatic therapy, MTAs should be combined with other drugs to target all modes of cancer cell invasion.

Taxanes – The Backbone of Medical Oncology

Drug development in oncology has witnessed a revolutionary growth from its humble beginning with nitrogen mustard in 1940 to immunotherapy in 1986 (Interferon alpha). The arsenal of cytotoxics is ever increasing, contributing to better survival outcomes and improved quality of life. Over the years, many cytotoxics have fallen out of favor too, due to its side effects and availability of drugs with better efficacy and toxicity profile. Taxane, a microtubule stabilizing agent extracted from the poisonous Yew tree, was discovered in 1964 and came into clinical use in 1992 with its approval for ovarian cancer. This group has grown into a cornerstone of many treatment protocols, spanning multiple tumor types. This review discusses in brief the salient features of cytotoxic agents in this drug group, its history, physico-chemical properties, mechanism of action, pharmacodynamics, and pharmacokinetics. Though the benefits of taxanes are well understood, there are unique problems associated with the use of taxanes and there is an expanding literature on taxane resistance. We briefly look at the resistance mechanisms. There have been significant efforts to circumvent the problems related to conventional taxanes, with an attempt at creating newer carrier molecules and adjunct drugs with taxanes, which is slowly gaining traction in clinical practice.

Efficacy and Safety of Chemotherapy Regimens in Advanced or Metastatic Bladder and Urothelial Carcinomas: An Updated Network Meta-Analysis

Background: Gemcitabine plus cisplatin (GC) and methotrexate, vinblastine, adriamycin, and cisplatin (MVAC) have been the first-line treatments for advanced or metastatic urothelial carcinoma (AMUC). However, their effects are unsatisfactory, and more drugs and regimens still need to be explored.

Objective: We aimed to comprehensively compare all possible regimens with GC or MVAC in randomized controlled trials (RCTs) by network meta-analysis.

Methods: We searched the PubMed, Embase, and Cochrane databases for RCTs that evaluated regimens compared to GC or MVAC on AMUC patients. The major outcomes were progression-free survival (PFS), overall survival (OS), and objective response rate (ORR). A network meta-analysis was used to assess the effectiveness and safety of the included treatment regimens, and the regimens were then clustered by the average linkage method.

Results: A total of 19 trials that assessed 3,363 AMUC patients were included. For PFS, paclitaxel plus GC (PGC) was significantly superior to GC (log hazard ratio (HR): −0.16; 95% confidence interval (CI): −0.32, 0.00) with a moderate level of reliability. However, there was no significant difference between PGC and MVAC (log HR: −0.03; 95% CI: −0.27, 0.20). For OS, PGC was significantly superior to GC (log HR:−0.17; 95% CI: −0.33, −0.00) with a moderate reliability level but not significantly different from MVAC (log HR: −0.10; 95% CI: −0.35, 0.15). Analysis of ORR showed that PGC was superior to MVAC (log odds ratio (OR): 0.59; 95% CI: 0.02, 1.16) with a low reliability level and GC (log OR: 0.41; 95% CI: 0.12, 0.71) with a moderate reliability level. In the cluster results, PGC and sorafenib plus GC (GCS) exhibited relative advantages in efficiency, followed by MVAC and apatorsen plus GC (GCA); however, PGC, gemcitabine plus carboplatin (GP), and MVAC had more serious side effects.

Conclusions: In our analysis, PGC was superior to MVAC and GC in only the ORR results and superior to GC in the OS and PFS results but was not significantly different from MVAC. More individualized therapies with targeted drugs need to be studied.

[Spectrometric analyses of larotaxel and larotaxel liposomes quantification by high performance liquid chromatography]

OBJECTIVE

Larotaxel is a new chemical structure drug, which has not been marketed worldwide. Accordingly, the standard identification and quantification methods for larotaxel remain unclear. The spectrometric analyses were performed for verifying weight molecular formula, molecular weight and chemical structure of larotaxel. Besides, a quantification method was developed for measuring larotaxel in the liposomes.

METHODS

The molecular formula, molecular weight and chemical structure of larotaxel were studied by using mass spectrometry (MS), infra-red (IR), nuclear magnetic resonance (NMR) and ultraviolet-visible (UV-vis) spectrometric techniques. The absorption wavelength of larotaxel was investigated by UV-vis spectrophotometry full-wavelength scanning. Besides, a quantification method was developed by high performance liquid chromatography (HPLC), and then validated by measuring the encapsulation efficacy of larotaxel liposomes.

RESULTS

The four spectral characteristics of larotaxel were revealed and the corresponding standard spectra were defined. It was confirmed that larotaxel had the structure of tricyclic diterpenoids, with the molecular formula of C45H53NO14, the molecular weight of 831.900 1, and the maximum absorption wavelength of 230 nm. The quantitative method of larotaxel was established by using HPLC with a reversed phase C18 column (5 μm, 250 mm×4.6 mm), a mobile phase of acetonitrile-water (75:25, volume/volume), and a detection wavelength of 230 nm. The validation study exhibited that the established HPLC method was stable, and had a high recovery and precision in the quantitative measurement of larotaxel in liposomes. In addition, a new kind of larotaxel liposomes was also successfully prepared. The particle size of the liposomes was about 105 nm, with an even size distribution. And the encapsulation efficiency of larotaxel in the liposomes was above 80%.

CONCLUSION

The present study offers reference standard spectra of larotaxel, including MS, IR, NMR, and UV-vis, and confirms the molecular formula, molecular weight and chemical structure of larotaxel. Besides, the study develops a rapid HPLC method for quality control of larotaxel liposomes.

Management of metastatic bladder cancer

Important advances in the understanding of the biology and mechanisms of tumor progression of urothelial carcinoma (UC) have been achieved over the past decade. The treatment landscape for advanced-stage, unresectable or metastatic UC has shifted dramatically over a short period of time, with 6 new therapeutic agents available for clinical use. The use of traditional chemotherapy and new immune checkpoints inhibitors (ICIs) directed at programmed cell-death protein 1 (PD-1) or its ligand has led to unprecedented survival benefits in selected patients with metastatic UC. Data show that anti-PD-1 ICIs are not only improving long-term clinical benefit, but also quality of life for patients in the second-line setting. In the front-line setting, regulatory agencies have restricted the indications of atezolizumab and pembrolizumab (both ICIs) to patients with PD-L1positivity with advanced UC and who are platinum-ineligible. Very recently, erdafitinib, a pan-FGFR inhibitor, has been granted accelerated approval by FDA for platinum-pretreated advanced metastatic UC with susceptible FGFR3 or FGFR2 genetic alterations. Enfortumab vedotin, an antibody-drug conjugate, have been granted breakthrough designation by the FDA for the treatment of metastatic UC. Here we review the clinical trial data that have established standard-of-care treatment for advanced-stage UC. In addition, mechanisms of resistance and biomarkers of response to platinum-based chemotherapies and immunotherapies are also discussed, along with the clinical benefits and limitations of these therapies.

Evolution of randomized controlled trials and surrogacy of progression-free survival in advanced/metastatic urothelial cancer

BACKGROUND

Clinical trials in advanced/metastatic urothelial cancer have been difficult to perform. We review the current characteristics of randomized controlled trials (RCTs) and evaluate whether PFS could be a potential surrogate endpoint for overall survival (OS) in advanced/metastatic urothelial cancer.

METHODS

We identified trials by a systematic review of Medline, Embase, and the Cochrane Central Register of Controlled Trials from inception to April 2017. We included RCTs of patients with locally advanced/metastatic urothelial cancer that involved systemic therapy as an intervention, and those with reported hazards ratios (HRs) and corresponding 95% confidence intervals (CIs) for both OS and PFS, or provided Kaplan-Meier curves from which HRs and 95% CI could be calculated. The correlation coefficient between log of HRs for OS and PFS was calculated using linear regression weighted by sample size.

RESULTS

Forty eight trials that enrolled 7019 patients were included in the review and 24 RCTs were included in the surrogacy analysis. 27(56.3%) of identified 48 RCTs were phase II trials, and the median sample size was 107(range, 30-626) for all RCTs. The correlation coefficient between log HR for PFS and log HR for OS was 0.79 (95% CI, 0.58-0.91). The correlation coefficient increased to 0.87 (95% CI, 0.72-0.94) after excluding the only trial with immune checkpoint inhibitor. Multiple sensitivity analyses did not change the results..aph."/> CONCLUSIONS: PFS is strongly correlated with OS in trials of advanced/metastatic urothelial cancer assessing the treatment benefit of new drugs And PFS warrants further exploration as a surrogate endpoint in clinical trial datasets.

The Search for Anticancer Agents from Tropical Plants

Many of the clinically used anticancer agents in Western medicine are derived from secondary metabolites found in terrestrial microbes, marine organisms, and higher plants, with additional compounds of this type being currently in clinical trials. If plants are taken specifically, it is generally agreed that the prospects of encountering enhanced small organic-molecule chemical diversity are better if tropical rather than temperate species are investigated in drug discovery efforts. Plant collection in tropical source countries requires considerable preparation and organization to conduct in a responsible manner that abides by the provisions of the 1992 Rio Convention of Biological Diversity and the 2010 Nagoya Protocol on Access to Genetic Resources. Correct taxonomic identifications and enhanced procedures for processing and documenting plant samples when collected in often difficult terrain are required. Phytochemical aspects of the work involve solvent fractionation, known compound dereplication, preliminary in vitro testing, and prioritization, leading to "activity-guided fractionation", compound structure determination, and analog development. Further evaluation of lead compounds requires solubility, formulation, preliminary pharmacokinetics, and in vivo testing in suitable models. Covering the work of the authors carried out in two sequential multidisciplinary, multi-institutional research projects, examples of very promising compounds discovered from plants acquired from Africa, Southeast Asia, the Americas, and the Caribbean region, and with potential anticancer activity will be mentioned. These include plant secondary metabolites of the diphyllin lignan, cyclopenta[b]benzofuran, triterpenoid, and tropane alkaloid types.

Screen Failure Rates in Contemporary Randomized Clinical Phase II/III Therapeutic Trials in Genitourinary Malignancies

BACKGROUND

Screen failures, defined as individuals who undergo screening but are not enrolled in a clinical trial, incur significant costs without contributing valuable data to the study. Despite these costs, there are few published data about the rate or reasons for screen failures in advanced genitourinary cancer clinical trials.

MATERIALS AND METHODS

We reviewed 50 phase II and III trials in advanced genitourinary cancers conducted between 1999 and 2016.

RESULTS

Of the 50 trials, only 48% (24 of 50) published screen failure rates: 68% (13 of 19) of those in prostate cancer, 33% (6 of 18) in kidney cancer, and 58% (5 of 13) in bladder cancer. Among the phase III trials in prostate cancer, the mean screen failure rate was 26% (range, 12%-45%). The main reason for screen failure was reported as ineligibility. Among the phase III trials in kidney cancer, the mean screen failure rate was 25% (range, 21%-29%), with the most frequent reasons being ineligibility and patient refusal. Among the phase II/III trials in bladder cancer, the mean screen failure rate was 19% (range, 4%-28%), with the main reasons being ineligibility and patient refusal.

CONCLUSION

Contemporary trials in genitourinary cancer reported screen failure rates of approximately 20% to 30%. Many trials did not report on the numbers of, and reasons for, screen failures. Greater standardization of definitions, methods, and reporting are needed to better understand and decrease screen failure rates in genitourinary cancer clinical trials.

Early investigational tubulin inhibitors as novel cancer therapeutics

INTRODUCTION

Microtubules represent one of the most logical and strategic molecular targets amongst the current targets for chemotherapy, alongside DNA. In the past decade, tubulin inhibitors as cancer therapeutics have been an area of focus due to the improved understanding and biological relevance of microtubules in cellular functions. Fueled by the objective of developing novel chemotherapeutics and with the aim of establishing the benefits of tubulin inhibition, several clinical trials have been conducted with others ongoing.

AREA COVERED

At present, the antitubulin development pipeline contains an armful of agents under clinical investigation. This review focuses on novel tubulin inhibitors as cancer therapeutics. The article covers the agents which have completed the phase II studies along with the agents demonstrating promising results in phase I studies.

EXPERT OPINION

Countless clinical trials evaluating the efficacy, safety and pharmacokinetics of novel tubulin inhibitors highlights the scientific efforts being paid to establish their candidature as cancer therapeutics. Colchicine binding site inhibitors as vascular disrupting agents (VDAs) and new taxanes appear to be the most likely agents for future clinical interest. Numerous agents have demonstrated clinical benefits in terms of efficacy and survival in phase I and II studies. However conclusive benefits can only be ascertained on the basis of phase III studies.

Taxane anticancer agents: a patent perspective

INTRODUCTION

Paclitaxel and docetaxel were two epoch-making anticancer drugs and have been successfully used in chemotherapy for a variety of cancer types. In the year 2010, a new taxane, cabazitaxel, was approved by FDA for use in combination with prednisone for the treatment of metastatic hormone-refractory prostate cancer. Albumin-bound paclitaxel (nab™-paclitaxel; abraxane) nanodroplet formulation was another notable invention (FDA approval 2005 for refractory, metastatic, or relapsed breast cancer). Abraxane in combination with gemcitabine for the treatment of pancreatic cancer was approved by FDA in 2013. Accordingly, there have been a huge number of patent applications dealing with taxane anticancer agents in the last 5 years. Thus, it is a good time to review the progress in this area and find the next wave for new developments.

AREA COVERED

This review covers the patent literature from the year 2010 to early 2015 on various aspects of taxane-based chemotherapies and drug developments.

EXPERT OPINION

Three FDA-approved taxane anticancer drugs will continue to expand their therapeutic applications, especially through drug combinations and new formulations. Inspired by the success of abraxane, new nano-formulations are emerging. Highly potent new-generation taxanes will play a key role in the development of efficacious tumor-targeted drug delivery systems.

The Impact of Adding Taxanes to Gemcitabine and Platinum Chemotherapy for the First-Line Therapy of Advanced or Metastatic Urothelial Cancer: A Systematic Review and Meta-analysis

CONTEXT

Gemcitabine/platinum chemotherapy is the most widely used first-line regimen for metastatic urothelial carcinoma, and the potential improvement of adding taxanes needs to be clarified.

OBJECTIVE

To study the survival impact of taxane plus gemcitabine/platinum compared with gemcitabine/platinum alone as upfront therapy.

EVIDENCE ACQUISITION

Literature was searched for studies including gemcitabine/platinum ± taxanes (paclitaxel or docetaxel only). We pooled trial level data including the median, proportions, and confidence intervals on response-rate, progression-free survival, overall survival (OS), and side effects. Univariable and multivariable regression models evaluated the prognostic role of addition of taxanes after adjusting for platinum type, performance status 2, and the presence of visceral metastases. Data were weighted by the logarithm of the trial sample size.

EVIDENCE SYNTHESIS

Thirty-five arms of trials including 2,365 patients were selected (seven with taxanes [n=617], and 28 arms without taxanes [n=1,748]). Median OS was univariably significantly different (p=0.019) between trials with and without taxanes. Across trials, the median 'median OS' amongst trials containing taxanes was 15.5 mo, compared with 12.5 mo in trials which did not. Multivariably, visceral disease and performance status were significantly associated with OS, and the addition of taxanes trended toward significantly better OS (p=0.056) and increase in grade ≥ 3 neurotoxicity (p=0.051), regardless of specific platinum agent used.

CONCLUSIONS

In this meta-analysis, adding taxanes to gemcitabine and platinum showed a trend for improved OS and higher grade ≥ 3 neurotoxicity. Improvements in patient selection and the evaluation of a more potent and tolerable tubulin inhibitor in combination with gemcitabine/platinum in a well-powered trial are the critical next steps.

PATIENT SUMMARY

In this report, a trend for improved overall survival and worse neurotoxicity was observed for adding a taxane to first-line gemcitabine/platinum chemotherapy for metastatic urothelial carcinoma. More effective taxanes should be investigated further in urothelial carcinoma in combination with gemcitabine/platinum.

Drug-Resistant Urothelial Cancer Cell Lines Display Diverse Sensitivity Profiles to Potential Second-Line Therapeutics

Combination chemotherapy with gemcitabine and cisplatin in patients with metastatic urothelial cancer of the bladder frequently results in the development of acquired drug resistance. Availability of cell culture models with acquired resistance could help to identify candidate treatments for an efficient second-line therapy. Six cisplatin- and six gemcitabine-resistant cell lines were established. Cell viability assays were performed to evaluate the sensitivity to 16 different chemotherapeutic substances. The activity of the drug transporter ATP-binding cassette transporter, subfamily B, member 1 (ABCB1, a critical mediator of multidrug resistance in cancer) was evaluated using fluorescent ABCB1 substrates. For functional assessment, cells overexpressing ABCB1 were generated by transduction with a lentiviral vector encoding for ABCB1, while zosuquidar was used for selective inhibition. In this study, 8 of 12 gemcitabine- or cisplatin-resistant cell lines were cross-resistant to carboplatin, 5 to pemetrexed, 4 to methotrexate, 3 to oxaliplatin, 5-fluorouracil, and paclitaxel, and 2 to cabazitaxel, larotaxel, docetaxel, topotecan, doxorubicin, and mitomycin c, and 1 of 12 cell lines was cross-resistant to vinflunine and vinblastine. In one cell line with acquired resistance to gemcitabine (TCC-SUP^rGEMCI²⁰), cross-resistance seemed to be mediated by ABCB1 expression. Our model identified the vinca alkaloids vinblastine and vinflunine, in Europe an already approved second-line therapeutic for metastatic bladder cancer, as the most effective compounds in urothelial cancer cells with acquired resistance to gemcitabine or cisplatin. These results demonstrate that this in vitro model can reproduce clinically relevant results and may be suitable to identify novel substances for the treatment of metastatic bladder cancer.