Epothilone Analogues Research Articles

Total Synthesis of an Epothilone Analogue Based on the Amide-Triazole Bioisosterism.

Epothilones are 16-membered macrolides that act as microtubule-targeting agents to tackle cancer. Many synthetic analogues have been investigated for their activity, yet often based on macrolide structures. A notable exception is Ixabepilone, an azalide whose metabolic stability and pharmacokinetics are significantly improved. Exploiting the amide-triazole bioisosterism, in this work we report the synthesis of the first generation of epothilones lacking the macrolide or azalide structure, with the ester or amide linkage replaced by a triazole unit. Together with the synthesis of this new analogue, computational and biological evaluations have been performed too.

A genetically engineered epothilone analog as a novel oral microtubule inhibitor: A clinical study of utidelone capsule for advanced breast cancer.

e13115 Background: Utidelone, a genetically engineered epothilone analog, is a potential best-in-class novel microtubule stabilizing agent. Utidelone injection was approved for advanced breast cancer in China in 2021. Utidelone is not susceptible to P-glycoprotein, leading to better oral bioavailability and successful development of an oral formulation-Utidelone Capsule (UTD2). As of now, there has been no oral microtubule stabilizing agent approved in China and the United States. UTD2 may benefit patients in various aspects including effectiveness, safety, better compliance, reduced medical cost, and facilitation of combination therapy, especially with other oral anti-cancer drugs. This is the first clinical study in China to investigate the efficacy and safety of UTD2 monotherapy for treatment of advanced breast cancer. Methods: This is an ongoing open-label, multi-center study (NCT05700084) consisting of three parts: dose escalation, bioavailability and food effect, and in combination with capecitabine for treatment of metastatic breast cancer. Here we report the preliminary results from single center for part I with determination of DLT and MTD as the primary objective, and efficacy, PK profile and safety in patients with pretreated metastatic breast cancer as the secondary objectives. Eligible patients are aged 18-70 years with confirmed advanced breast cancer refractory to prior standard therapies, and have an ECOG PS of 0-1, life expectancy ≥12weeks. Patients are treated with UTD2 monotherapy, at starting dose of 50 mg/m2/d-5day for two patients, with planned escalation (3+3) to 75 mg/m2/d-5day and 75 mg/m2/d-7day, then to 85 mg/m2/d-7day or down to 70 mg/m2/d-7day in a 21-day cycle. Results: As of 25th January 2024, 5 advanced breast cancer patients were enrolled, who had received prior treatment in advanced settings. Dose escalation is ongoing, and 75mg/m2/d-7day cohort is under evaluation. Four patients were evaluated for efficacy with an outcome of 2 PR (each for 50 and 75mg/m2/d-5day dose) and 2 SD (75mg/m2/d-5day dose) with treatment durations of 2 to 8 cycles. Most treatment-emergent adverse events (TEAEs) were Grade 1/2, manageable, and included peripheral sensory neuropathy (PN), dizziness and loss of appetite. There were two patients encountered Grade 3 TEAEs including one with PN and one with diarrhea/insomnia, that recovered through dose reduction or supportive treatment. No grade 4/5 adverse events and no treatment discontinuations due to AE were reported. There have been no DLTs and the MTD is not yet reached. Conclusions: These preliminary results suggested promising efficacy with a manageable safety profile of UTD2 in pretreated metastatic breast cancer patients. This study is still actively enrolling; further data will be provided at the time of presentation. Clinical trial information: NCT05700084 .

Utidelone for heavily pretreated metastatic castration-resistant prostate cancer after failing docetaxel treatment: An open-label, single-arm, phase II trial.

e17036 Background: The appropriate chemotherapy for metastatic castration-resistant prostate cancer (mCRPC) that progressed after docetaxel treatment remains unmet medical needs. Utidelone (UTD1) is a genetically engineered epothilone analog with antitumor activity in taxane-resistant cancers. UTD1 was approved for advanced breast cancer in 2021. This study was designed to evaluate the safety and efficacy of UTD1 in mCRPC. Methods: In this perspective, phase II clinical trial, men with progressive mCRPC after docetaxel and abiraterone, and/or enzalutamide, and/or apalutamide received UTD1 monotherapy treatment at a total dose of 150 mg/m2 for five days intravenous, every three weeks until disease progression, or intolerable toxicity, or death. We reported the preliminary results for potential benefits in this new treatment. The primary endpoint was prostate specific antigen (PSA) response rate, defined as a 50% or greater reduction in serum PSA. The secondary endpoint included investigators-assessed objective response rate (ORR) and disease control rate (DCR) according to RECIST v1.1, radiographic progression-free survival (rPFS) according to PCWG3 criteria, overall survival (OS), and safety. The trial was registered at Chinese Clinical Trial Registry (No. ChiCTR2200061635). Results: By January 31st, 2024, twenty-five mCRPC patients with a median age of 67 years were enrolled in this study at Sun Yat-sen University Cancer Center since March 23rd, 2022. Patients received an average of 4.2 lines of prior anticancer treatments: 100% of them received docetaxel, 96.0% of them received abiraterone, and 80.0% progressed after enzalutamide, and/or apalutamide. 28.0% of patients had visceral metastases, and 88.0% patients had bone metastases. At of the cut-off date, the PSA response rate was 16.0%. The median rPFS and OS were 4.9 months and 7.1 months, respectively. One patient had a durable response for 19.2 months and had been remaining on study treatment to date. One PR and four SD were observed in ten patients with measurable lesions, resulting in an overall ORR and DCR of 10.0% and 50.0%, respectively. The most common treatment-related adverse events (TRAEs) including peripheral sensory neuropathy (76.0%), dyspepsia (72.0%), anemia (64.0%), constipation (60.0%), fatigue (64.0%), nausea (36.0%), leukocytopenia (32.0%), arthralgia (32.0%), dizziness (32.0%), vomiting (20.0%), and diarrhea (20.0%) were manageable. The 3/4 grade TRAEs included anemia (16.0%), and diarrhea (4%). No treatment-related death occurred. Conclusions: UTD1 has demonstrated promising efficacy and favorable tolerance in heavily pretreated mCRPC patients after progression on docetaxel in the preliminary analyses. Additional randomized trials are warranted for this new regimen. Clinical trial information: ChiCTR2200061635.

Efficacy and safety of utidelone for the treatment of patients with locally advanced or metastatic non-small-cell lung cancer who have failed standard second-line treatment: A phase 2 clinical trial (BG01-1801)

BackgroundChemotherapy remains the standard-of-care for many patients with locally advanced or metastatic non-small-cell lung cancer (NSCLC), but acquired resistance presents challenges. The aim of this open-label, multicenter phase 2 clinical trial was to determine the efficacy and safety of utidelone, a novel genetically engineered epothilone analog and microtubule-stabilizing agent, as a third- or later-line treatment for locally advanced or metastatic NSCLC. MethodsPatients who had failed standard second-line treatment (including platinum-containing chemotherapy or targeted therapy) received utidelone (40 mg/m2 via intravenous injection daily, day 1–5) every 21 days. The primary endpoint was the objective response rate (ORR). Secondary endpoints were the duration of response (DoR), progression-free survival (PFS), overall survival (OS), and safety. ResultsFrom March 12, 2019 to January 18, 2021, 26 pretreated patients with locally advanced or metastatic NSCLC (100% of patients had received prior platinum and 65.4% patients had received prior taxane treatment) were enrolled (80.8% of patients had adenocarcinoma). At baseline, nine (34.6%) patients had received second-line treatment, 10 (38.5%) patients had received third-line treatment, and seven (26.9%) patients had received fourth- or later-line treatment. By the data cut-off date of August 10, 2021, the median follow-up was 7.49 months (range, 1.4–26.7 months). The ORR was 15.4% (95% confidence interval [CI], 4.4%–34.9%) in the intention-to-treat (ITT) cohort (N = 26) and 19.0% (95% CI, 5.4%–41.9%) in the per-protocol (PP) cohort (N = 21). The disease control rate was 69.2% (95% CI, 48.2%–85.7%) and 81.0% (95% CI, 58.1%–94.6%) in the ITT and PP cohorts, respectively. The median DoR was 4.1 months (95% CI, 3.1–5.1 months) in the ITT cohort. The median PFS was 4.37 months (95% CI, 2.50–5.29 months) in the ITT cohort and 4.37 months (95% CI, 2.50–9.76 months) in the PP cohort. The median OS was not reached, and the 12-month OS rate was 69% (95% CI, 45.1%–84.1%). Grade 3/4 treatment-emergent adverse events occurred in 38.5% of patients, and the most common was peripheral neuropathy (23.1%, all Grade 3), which was manageable with dose modifications. ConclusionsIn this clinical trial, utidelone showed promising efficacy and had a manageable safety profile. Further clinical studies are warranted to confirm its role in NSCLC treatment. Trial registrationNo.NCT03693547; https://classic.clinicaltrials.gov.

Anti-HER2 antibody inetetamab plus camrelizumab and utidelone for pretreated HER2-positive metastatic breast cancer: Final results from the phase 2 ICU trial.

1042 Background: We previously reported (Yan, ASCO 2022) promising efficacy and acceptable safety of anti-HER2 antibody inetetamab in combination with camrelizumab and utidelone regimen in preliminary 20 HER2-positive metastatic breast cancer (MBC) patients who progressed after at least two lines of HER2-directed therapies with trastuzumab and TKIs. Inetetamab is a novel anti-HER2 antibody. Camrelizumab is an anti-programmed death receptor 1 [PD-1] antibody. Utidelone, a genetically engineered epothilone analogue, has shown promising efficacy in heavily pretreated MBC. Here we report the final ICU study results. Methods: In the ICU study (NCT04681287), patients received intravenous camrelizumab (200 mg once every 3 weeks), inetetamab (initial dose of 8 mg/kg, then 6 mg/kg, once every 3 weeks), and utidelone (30 mg/m2, days 1-5, every 3 weeks) until disease progression or intolerable toxicity. The primary endpoint was 3-month progression-free survival (PFS) rate according to the Response Evaluation Criteria in Solid Tumors, version 1.1. Secondary endpoints included objective response rate (ORR), PFS and safety. Simon’s two-stage design was adopted for this study. All AEs were graded according to the grading criteria in the Common Terminology Criteria for the Evaluation of Adverse Events, 5th edition. Results: From Apr 23 2021 to Sept 1 2022, a total of 46 HER2-positive MBC patients were enrolled with median age of 52 (range 43-57). As of Jan 18, 2023, the median follow-up was 11.37 months. There were 12 patients (26.09%) with ER+/PR+, 7 patients (15.22%) with ER+/PR-, one patient (2.17%) with ER-/PR+, 26 patients (56.52%) with ER-/PR-. The median number of previous systemic therapies for advanced disease was three. Previous HER2-targeted therapies included trastuzumab (46 [100%]), TKIs (46 [100%], of which pyrotinib 39 [84.78%] and lapatinib 12 [26.09%]), pertuzumab (13 [28.26%]), and margetuximab (3 [6.52%]), T-DM1 or other HER2-ADC (7 [15.22%]). The 3-month PFS rate in 46 patients was 71.84%. The confirmed ORR was 28% (13/46), include one (2.17%) patient achieved complete response. The median PFS was 5.59 months. The most common treatment-related adverse events (TRAEs) were peripheral neuropathy (40 [86.96%]), capillary proliferation (27 [58.7%]), and alopecia (17 [36.96%]). Grade ≥3 TRAEs included rash (3 [6.52%]), peripheral neuropathy (1 [2.17%]) and AST increase (1 [2.17%]). Moreover, there were no grade 4 or above TRAEs. No related treatment discontinuation or deaths occurred. Conclusions: Final efficacy and safety results were consistent with previous ICU study preliminary analyses. The ICU study showed a favorable benefit-risk profile and is an important option for Chinese patients with HER2-positive MBC after at least two lines of HER2-directed therapies with trastuzumab and TKIs. Clinical trial information: NCT04681287 .

Anti-HER2 antibody inetetamab plus camrelizumab and utidelone for pretreated HER2-positive advanced breast cancer: A single-arm, multicenter, phase 2 study.

e13030 Background: Treatment options for patients with HER2-positive breast cancer after progression on two or more lines of HER2-directed therapies are scarce. Inetetamab, a novel anti-HER2 antibody, exhibits the same binding affinity to HER2 antigen and antibody-dependent cell-mediated cytotoxicity as trastuzumab. Previous studies have demonstrated the treatment potential of PD-1 inhibitor combined with HER2-targeted therapy in HER2-positive gastric or gastroesophageal junction cancer. Utidelone, a genetically engineered epothilone analogue, has shown promising efficacy in heavily pretreated metastatic breast cancer. This study aimed to investigated inetetamab plus camrelizumab (anti-PD-1 antibody) and utidelone in patients with HER2-positive recurrent or metastatic breast cancer who had progressed after at least two lines of HER2-directed therapies with trastuzumab and tyrosine kinase inhibitors (TKIs). Methods: In this phase 2 study (NCT04681287), patients received intravenous camrelizumab (200 mg once every 3 weeks), inetetamab (8 mg/kg loading dose then 6 mg/kg, day 1), and utidelone (30 mg/m2, days 1-5) until disease progression or intolerable toxicity. The primary endpoint was 3-month progression-free survival (PFS) rate according to the Response Evaluation Criteria In Solid Tumors, version 1.1. Secondary endpoints included objective response rate (ORR), PFS, overall survival, and safety. Simon’s two-stage design was adopted for this study. Results: Between April 2021 and January 2022, a total of 27 patients were enrolled. As of January 2022, 20 patients could be analyzed. The median number of previous systemic therapies for advanced disease was three. Previous HER2-targeted therapies included trastuzumab (20 [100%]), pyrotinib (17 [85%]), lapatinib (7 [35%]), pertuzumab (3 [15%]), and margetuximab (2 [10%]). The first stage required 10 patients, and 8 of them were free from progression at 3 months. The study proceeded to the second stage for another 31 patients, and the accrual is ongoing. The 3-month PFS rate in 20 patients was 75%. The ORR was 30% (6/20); one (5%) patient achieved complete response. The most common treatment-related adverse events (TRAEs) were peripheral neuropathy (19 [98%]), capillary proliferation (19 [98%]), alopecia (18 [90%]), and fatigue (7 [35%]). Grade ≥3 TRAEs included peripheral neuropathy (2 [10%]) and rash (1 [5%]). No treatment-related treatment discontinuation or deaths occurred. Conclusions: Inetetamab plus camrelizumab and utidelone showed promising efficacy and acceptable safety profile in patients with HER2-positive advanced breast cancer after progression on at least two lines of HER2-directed therapies with trastuzumab and TKIs. Clinical trial information: NCT04681287.

31P Efficacy and safety of utidelone in treatment-refractory advanced non-small cell lung cancer

Chemotherapy remains the standard-of-care for most patients with advanced NSCLC. Utidelone, a genetically engineered epothilone analogue, demonstrated marked and durable antitumor activity in patients with metastatic breast cancer. Here, we reported the efficacy and safety of utidelone for advanced NSCLC refractory to second-line treatment. This was an open label, multicenter, phase II study (NCT03693547). Eligible criteria included age 18-70, ECOG performance status of 0-1, failure of previous standard second-line treatment (including platinum-containing chemotherapy with or without targeted therapy). All patients received the recommended dose of utidelone (40mg/m2/d intravenously on d1-d5, 21d per cycle). The primary endpoint was objective response rate (ORR). Safety was analyzed in all patients who received at least one dose of study treatment. From April 22, 2019 to January 22, 2021, 26 patients were enrolled, with a median age of 55.3 (range 39-68) years. 61.5% of patients had an ECOG PS of 1, 80.8% had adenocarcinoma, and 65% were pre-treated with taxol. At baseline, pre-treatment in the second-line, third-line, and fourth-line or over were present in 34.6%, 38.5%, and 26.9%, respectively. Efficacy was evaluated in full analysis set (FAS) (n=26) and per protocol set (PPS) (n=21) with an ORR of 15.4% (95% CI 4.4, 34.9) and 19.0% (95% CI 5.4, 41.9), respectively. DCR were 69.2% (95% CI 48.2, 85.7) and 81.0% (95% CI 58.1, 94.6) in FAS and PPS, respectively. The median PFS was 4.37 (95% CI 2.50 5.29) months in FAS and 4.37 (95% CI 2.50, 9.76) months in PPS. OS was not reached but 12 month-OS rate was 69.0% (95% CI 45.1%, 84.1%) in FAS and 71.0% (95% CI 42.7%, 87.1%) in PPS. 26 (100%) patients had at least one adverse event (AE), 2 (7.7%) experienced discontinuation of utidelone and 8 (30.8%) had a dose reduction. Common grade 3-4 AEs were peripheral neuropathy (19.2%, all were grade 3), lymphopenia (7.7%), elevated glutamyltransferase (7.7%), and hyponatremia (7.7%). Notably, low incidences of liver and renal toxicities, and very limited gastrointestinal toxic effect were observed. These findings demonstrate that utidelone may be an effective treatment option for advanced NSCLC refractory to second-line treatment.

Synthesis of a New 10,11-Didehydro Analog of Epothilone D

Synthesis of a New 10,11-Didehydro Analog of Epothilone D

Ganglioside Monosialic Acid Alleviates Peripheral Neuropathy Induced by Utidelone Plus Capecitabine in Metastatic Breast Cancer From a Phase III Clinical Trial.

PurposeThis study aimed to assess the efficacy of utidelone, a novel genetically engineered epothilone analog, combined with capecitabine in our center and, furthermore, to identify whether ganglioside monosialic acid (GM1) improved chemotherapy-induced peripheral neurotoxicity (CIPN).MethodsFifty-five eligible female patients with metastatic breast cancer were enrolled in our single-center phase III BG01-1323L trial. Utidelone combined with capecitabine-induced peripheral neuropathy was analyzed, and susceptible genes were detected in a germline panel by next-generation sequencing (NGS).ResultsIn our single-center study, median progression-free survival and overall survival (OS) improved in the utidelone plus capecitabine group (mPFS: 238 vs. 189 days, P = 0.263; OS: 20.9 vs. 12.9 months, P = 0.326). The median time to severe CIPN reported was 29 days in grade 1, 49 days in grade 2, and 103 days in grade 3. Greatly longer improvement time was indicated in grade 1 (77 vs. 20 days in grade 2, 13 days in grade 3). In the combined group, 19 patients with G2 or G3 CIPN were assigned to the GM1 group and 9 patients to the control group. After intervention, the GM1 group was reported to demonstrate a statistically lower incidence of grade 3 CIPN [GM1 group: 1 of 19 (5.3%); control group: 4 of 9 (44.4%), P = 0.026]. However, there were no statistically significant differences in germline single nucleotide polymorphism (SNP) between grade 3 and grade 1 CIPN cohorts.ConclusionGanglioside monosialic acid potentially decreases severe utidelone plus capecitabine-induced peripheral neuropathy in metastatic breast cancer, and further investigation is needed to validate the manageable efficacy of GM1 in CIPN.Clinical Trial RegistrationClinicalTrials.gov, identifier NCT02253459.

Abstract P2-15-10: Utidelone plus capecitabine versus capecitabine for heavily pretreated metastatic breast cancer and CIPN: Analysis of a single centre cohort

Abstract Objective In BG01-1323L trial, Utidelone, a novel genetically engineered epothilone analogue, plus capecitabine showed improved progression-free survival and overall survival in heavily pretreated metastatic breast cancer prior to anthracycline and taxane. Chemotherapy-induced peripheral neurotoxicity (CIPN) is the most common dose-limiting toxicity of utidelone plus capecitabine. The most samples were provided and CIPN related germline mutations were analyzed in our single centre. Recent study indicated ganglioside-monosialic acid (GM1) could decrease the incidence and severity of taxane-induced peripheral neuropathy. The aims of this study were to assess the efficacy of utidelone plus capecitabine in our centre and predictive role of mutations for CIPN, further to identify whether GM1 or Trivitamin B (IIIvB) improved CIPN. Methods Fifty-four eligible female patients with metastatic breast cancer refractory to anthracycline and taxane were enrolled in our single centre in Phase 3 BG01-1323L trial. We randomly assigned to 39 cases in utidelone plus capecitabine and 16 cases in capecitabine alone until disease progression or unacceptable toxicity occurred. Progression-free survival and overall survival were assessed in our centre with the Kaplan-Meier product-limit method and Safety including neurotoxicity was both assessed in all participants and in our single centre. SNP were detected in germline panel including ABCB1, CDA, CYP19A1, CYP 2D6, DPYD, ERCC1, GSTP1, NQO1, TP53, TYMS and UGT1A1 and 363-genes panel was detected by NGS only in our centre. Results In our single centre, median progression-free survival in the utidelone plus capecitabine group was 139 days compared with 137 days in the capecitabine alone group, p=0.642. Median overall survival improved in combined therapy (626 days vs 409 days, p=0.026). Peripheral neuropathy was the most common grade 3 adverse event in the utidelone plus capecitabine group. Compared with the ITT group, more grade1/2 CIPN (87.2% [34/39] in our centre vs 59% [89/270] in ITT) but less grade 3 (12.8% [5/39] in our centre vs 22% [92/270] in ITT) occurred in our single centre cohort. The potential reason for this difference of CIPN G3 was the palliative treatment target CIPN with GM1 or IIIvB in our single centre. Our analysis revealed that median time and duration of UIPN G3 was 10.29 weeks and 3.12 weeks in ITT and 15.67 weeks and 0.86 weeks in our single centre. Treatment with GM1 or IIIvB was associated with delay the median of CIPN G3 (10.29 weeks vs. 15.67 weeks) and reduction of the duration time (3.12 weeks vs. 0.86 weeks) in our centre compared to the ITT cohort. A tendency to extend the time of CIPN I/II was observed between GM1 and IIIvB groups (Grade I: 95.13 days vs 87.57 days, Grade II: 69.09 days vs 48.51 days). No associated germline SNP was found in Grade 3 CIPN and AXIN2, ATM and SMARCA4 mutation was associated with increased incidence CIPN by 363-gene panel. Conclusion Utidelone plus capecitabine was more efficacious compared with capecitabine alone for progression-free survival with mild toxicity except for CIPN, less grade 3 CIPN was assessed in our single centre with GM1 and IIIvB, further investigation need to validate manageable efficacy of GM1 or IIIvB in CIPN in patients with utidelone plus capecitabine, as an effective option for patients with metastatic breast cancer. Citation Format: Junnnan Xu, Tao Sun. Utidelone plus capecitabine versus capecitabine for heavily pretreated metastatic breast cancer and CIPN: Analysis of a single centre cohort [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P2-15-10.

Synthesis, Microtubule-Binding Affinity, and Antiproliferative Activity of New Epothilone Analogs and of an EGFR-Targeted Epothilone-Peptide Conjugate.

A new simplified, epoxide-free epothilone analog was prepared incorporating an N-(2-hydroxyethyl)-benzimidazole side chain, which binds to microtubules with high affinity and inhibits cancer cell growth in vitro with nM potency. Building on this scaffold, a disulfide-linked conjugate with the purported EGFR-binding (EGFR, epidermal growth factor receptor) peptide GE11 was then prepared. The conjugate retained significant microtubule-binding affinity, in spite of the size of the peptide attached to the benzimidazole side chain. The antiproliferative activity of the conjugate was significantly lower than for the parent scaffold and, surprisingly, was independent of the EGFR expression status of cells. Our data indicate that the disulfide-based conjugation with the GE11 peptide is not a viable approach for effective tumor-targeting of highly potent epothilones and probably not for other cytotoxics.

Synthesis & antitumor activity of epothilones B and D and their analogs.

Epothilone is a newly developed antitumor drug; its antitumor principle is to stop the cell cycle by binding to tubulin in tumor cells, promoting tubulin polymerization, inhibiting depolymerization of microtubules, and ultimately inducing apoptosis. There are many analogs of epothilone, such as epothilone B, epothilone D, ixabepilone, sagopilone, 21-amino-epothilone B and KOS-1584. Herein, the synthesis and antitumor activity of epothilones B and D were summed up. The antitumor activity of epothilone analogs was also compared. Synthesis of epothilone and its analogs is more complex, and choosing the proper synthetic method is very important. Moreover, these compounds have obvious antitumor effect. The epothilone and its analogs will continue to play an important role in the future treatment of tumors.

Phase III multicenter, randomized study of utidelone plus capecitabine versus capecitabine alone for heavily pretreated, anthracycline- and taxane-refractory metastatic breast cancer.

1003Background: Utidelone, a genetically engineered epothilone analog, showed excellent efficacy in phase II and III trials in terms of PFS as a primary end point and ORR as a secondary end point. ...

Ixabepilone in modern therapy of resistant breast cancer

Ixabepilone is an epothilone analog, active as a cytotoxic agent due to its ability to stabilize microtubules of tumor cells. Currently ixabepiloneis approved for treatment of metastatic breast cancer in patients previously treated with taxanes and anthracyclines. In this article we analyzed existing data about its efficacy in preoperative and adjuvant treatment settings as well as in systemic therapy of metastatic breast cancer. We discussed a role of ixabepilone in contemporary treatment of this disease.

Synthesis of a chiral block for С 1 –С 5 fragment of epothilones

Synthesis was developed of a new chiral block for epothilone analogs from R-(‒)-pantolactone.

From Natural Products to Designer Drugs: Development and Molecular Mechanisms Action of Novel Anti-Microtubule Breast Cancer Therapeutics.

Microtubule-targeted drugs (MTDs) have been on the forefront of breast cancer chemotherapy. Classic MTDs, such as paclitaxel and their semisynthetic derivatives, have achieved considerable success in the clinical management of breast neoplasms. In order to improve the specificity and to reduce undesirable, dose-limiting toxicities of these drugs, a plethora of novel compounds are being synthesized and investigated in laboratories worldwide. Due to their crucial roles during cell division, and to the fact that the suppression of their innate 'dynamic instability' can arrest cell cycle progression, microtubules formed an attractive target for cancer chemotherapy. Kadcyla (ado-trastuzumab emtansine), Halaven (eribulin mesylate), and Ixempra (Ixabepilone) are three relatively-novel, microtubule-targeting antibreast cancer drugs. Kadcyla was developed by conjugating a very potent derivative of the natural product maytansine to trastuzumab, a HER2-targeted monoclonal antibody. Kadcyla is a double-edged weapon, that is, it prevents receptor dimerization to inhibit cell proliferation, and then it enters inside the target tumour cell by receptor-mediated endocytosis and ensures death of the cell. Halaven (eribulin mesylate), created by simplifying the structure of the marine sponge-derived molecule Halichondrin B, works primarily by suppressing the growth rates of microtubules and thereby inducing cell cycle arrest and cell death. Ixabepilone, the semisynthetic analogue of epothilone B, suppresses the shortening rates of dynamic microtubules resulting in cell cycle inhibition and cell death. In order to improve the efficacy and reduce drug-induced side effects, novel therapeutic strategies, including liposome-mediated drug delivery, are being investigated.

The Application of REDOR NMR to Understand the Conformation of Epothilone B.

The structural information of small therapeutic compounds complexed in biological matrices is important for drug developments. However, structural studies on ligands bound to such a large and dynamic system as microtubules are still challenging. This article reports an application of the solid-state NMR technique to investigating the bioactive conformation of epothilone B, a microtubule stabilizing agent, whose analog ixabepilone was approved by the U.S. Food and Drug Administration (FDA) as an anticancer drug. First, an analog of epothilone B was designed and successfully synthesized with deuterium and fluorine labels while keeping the high potency of the drug; Second, a lyophilization protocol was developed to enhance the low sensitivity of solid-state NMR; Third, molecular dynamics information of microtubule-bound epothilone B was revealed by high-resolution NMR spectra in comparison to the non-bound epothilone B; Last, information for the macrolide conformation of microtubule-bound epothilone B was obtained from rotational-echo double-resonance (REDOR) NMR data, suggesting the X-ray crystal structure of the ligand in the P450epoK complex as a possible candidate for the conformation. Our results are important as the first demonstration of using REDOR for studying epothilones.

Synthesis and Evaluation of a Linkable Functional Group-Equipped Analogue of the Epothilones.

An approach to the validation of a linker strategy for the epothilone family of microtubule-stabilizing agents is reported. An analogue of epothilone B in which the C(6) methyl group has been replaced with a 4-azidobutyl group has been prepared by total chemical synthesis, and amides derived from the azido group have been shown to retain the activity of the parent compound. These results set the stage for an evaluation of the potential of the epothilones to serve as the drug component of antibody-drug conjugates and other selective tumor cell-targeting conjugates.

Utidelone plus capecitabine versus capecitabine alone for heavily pretreated metastatic breast cancer refractory to anthracyclines and taxanes: a multicentre, open-label, superiority, phase 3, randomised controlled trial

Utidelone, a genetically engineered epothilone analogue, has shown promise as a potential treatment for breast cancer in phase 1 and 2 trials. The aim of this phase 3 trial was to compare the efficacy and safety of utidelone plus capecitabine versus capecitabine alone in patients with metastatic breast cancer. We did a multicentre, open-label, superiority, phase 3, randomised controlled trial in 26 hospitals in China. Eligible participants were female patients with metastatic breast cancer refractory to anthracycline and taxane chemotherapy regimens. We randomly assigned participants (2:1) using computer based randomisation and block sizes of 6 to a 21-day cycle of either utidelone (30 mg/m2 intravenously once per day on days 1-5) plus capecitabine (1000 mg/m2 orally twice per day on days 1-14), or capecitabine alone (1250 mg/m2 orally twice per day on days 1-14), until disease progression or unacceptable toxicity occurred. Patients, physicians, and assessors were not masked to treatment allocation; however, an independent radiology review committee used to additionally assess response was masked to allocation. The primary endpoint was centrally assessed (by an independent radiology review committee) progression-free survival, and analysed using the Kaplan-Meier product-limit method in the intention-to-treat population. Safety was assessed in all participants who received at least one dose of study drug. Follow-up is ongoing. This study is registered at ClinicalTrials.gov, number NCT02253459. Between Aug 8, 2014, and Dec 14, 2015, we enrolled and randomly assigned 270 patients to treatment with utidelone plus capecitabine, and 135 to capecitabine alone. Median follow-up for progression-free survival was 6·77 months (IQR 3·81-10·32) for the utidelone plus capecitabine group and 4·55 months (2·55-9·39) for the capecitabine alone group. Median progression-free survival by central review in the utidelone plus capecitabine group was 8·44 months (95% CI 7·95-9·92) compared with 4·27 months (3·22-5·68) in the capecitabine alone group; hazard ratio 0·46, 95% CI 0·36-0·59; p<0·0001. Peripheral neuropathy was the most common grade 3 adverse event in the utidelone plus capecitabine group (58 [22%] of 267 patients vs 1 [<1%] of 130 patients in the capecitabine alone group). Palmar-plantar erythrodysaesthesia was the most prominent grade 3 adverse event in the capacitabine alone group (in 10 [8%] of 130 patients) and was the next most frequent grade 3 event in the utidelone plus capecitabine group (in 18 [7%] of 267 patients). 16 serious adverse events were reported in the combination therapy group (diarrhoea was the most common, in three [1%] patients) and 14 serious adverse events were reported in the monotherapy group (the most common were diarrhoea, increased blood bilirubin, and anaemia, in two [2%] patients for each event). 155 patients died (99 in the combination therapy arm, 56 in the monotherapy arm). All deaths were related to disease progression except for one in each group (attributed to pericardial effusion in the combination therapy group and dyspnoea in the monotherapy group) that were considered possibly or probably treatment-related. Despite disease progression with previous chemotherapies, utidelone plus capecitabine was more efficacious compared with capecitabine alone for the outcome of progression-free survival, with mild toxicity except for peripheral sensory neuropathy, which was manageable. The findings from this study support the use of utidelone plus capecitabine as an effective option for patients with metastatic breast cancer. Beijing Biostar Technologies, Beijing, China.

NEW ADVANCES IN THE TREATMENT OF BREAST CANCER: THE ROLE EPOTHILONES

The review considers information about the efficacy and safety of Ixabepilone as a monotherapy and as a component of combination therapy for advanced breast cancer. Successful treatment of metastatic breast cancer is often confounded by resistance to chemotherapy, in particular anthracyclines and taxanes. The limited number of effective treatment options for patients with more aggressive biological subtypes, such as triple-negative metastatic breast cancer, is especially important. A therapy clinically proven to be effective in this subtype would be of great value. Ixabepilone, a novel synthetic lactam analog of epothilone B, demonstrated better clinical outcomes in metastatic disease, particularly in triple-negative breast cancer and “intensivelytreated” variant. Most recently, studies have shown the activity of ixabepilone in the neoadjuvant setting, suggesting a role for this drug in primary disease.