Trastuzumab plus adjuvant chemotherapy for operable HER2-positive breast cancer

BACKGROUND

We present the combined results of two trials that compared adjuvant chemotherapy with or without concurrent trastuzumab in women with surgically removed HER2-positive breast cancer.

METHODS

The National Surgical Adjuvant Breast and Bowel Project trial B-31 compared doxorubicin and cyclophosphamide followed by paclitaxel every 3 weeks (group 1) with the same regimen plus 52 weeks of trastuzumab beginning with the first dose of paclitaxel (group 2). The North Central Cancer Treatment Group trial N9831 compared three regimens: doxorubicin and cyclophosphamide followed by weekly paclitaxel (group A), the same regimen followed by 52 weeks of trastuzumab after paclitaxel (group B), and the same regimen plus 52 weeks of trastuzumab initiated concomitantly with paclitaxel (group C). The studies were amended to include a joint analysis comparing groups 1 and A (the control group) with groups 2 and C (the trastuzumab group). Group B was excluded because trastuzumab was not given concurrently with paclitaxel.

RESULTS

By March 15, 2005, 394 events (recurrent, second primary cancer, or death before recurrence) had been reported, triggering the first scheduled interim analysis. Of these, 133 were in the trastuzumab group and 261 in the control group (hazard ratio, 0.48; P<0.0001). This result crossed the early stopping boundary. The absolute difference in disease-free survival between the trastuzumab group and the control group was 12 percent at three years. Trastuzumab therapy was associated with a 33 percent reduction in the risk of death (P=0.015). The three-year cumulative incidence of class III or IV congestive heart failure or death from cardiac causes in the trastuzumab group was 4.1 percent in trial B-31 and 2.9 percent in trial N9831.

CONCLUSIONS

Trastuzumab combined with paclitaxel after doxorubicin and cyclophosphamide improves outcomes among women with surgically removed HER2-positive breast cancer. (ClinicalTrials.gov numbers, NCT00004067 and NCT00005970.)

Cancer treatment by targeted drug delivery to tumor vasculature in a mouse model

In vivo selection of phage display libraries was used to isolate peptides that home specifically to tumor blood vessels. When coupled to the anticancer drug doxorubicin, two of these peptides-one containing an alphav integrin-binding Arg-Gly-Asp motif and the other an Asn-Gly-Arg motif-enhanced the efficacy of the drug against human breast cancer xenografts in nude mice and also reduced its toxicity. These results indicate that it may be possible to develop targeted chemotherapy strategies that are based on selective expression of receptors in tumor vasculature.

CHOP-like chemotherapy with or without rituximab in young patients with good-prognosis diffuse large-B-cell lymphoma: 6-year results of an open-label randomised study of the MabThera International Trial (MInT) Group

BACKGROUND

The MInT study was the first to show improved 3-year outcomes with the addition of rituximab to a CHOP (cyclophosphamide, doxorubicin, vincristine, and prednisone)-like regimen in young patients with good-prognosis diffuse large-B-cell lymphoma. Extended follow-up was needed to establish long-term effects.

METHODS

In the randomised open-label MInT study, patients from 18 countries (aged 18-60 years with none or one risk factor according to the age-adjusted International Prognostic Index [IPI], stage II-IV disease or stage I disease with bulk) were randomly assigned to receive six cycles of a CHOP-like chemotherapy with or without rituximab. Bulky and extranodal sites received additional radiotherapy. Randomisation was done centrally with a computer-based tool and was stratified by centre, bulky disease, age-adjusted IPI, and chemotherapy regimen by use of a modified minimisation algorithm that incorporated a stochastic component. Patients and investigators were not masked to treatment allocation. The primary endpoint was event-free survival. Analyses were by intention to treat. This observational study is a follow-up of the MInT trial, which was stopped in 2003, and is registered at ClinicalTrials.gov, number NCT00400907.

FINDINGS

The intention-to-treat population included 410 patients assigned to chemotherapy alone and 413 assigned to chemotherapy plus rituximab. After a median follow-up of 72 months (range 0·03-119), 6-year event-free survival was 55·8% (95% CI 50·4-60·9; 166 events) for patients assigned to chemotherapy alone and 74·3% (69·3-78·6; 98 events) for those assigned to chemotherapy plus rituximab (difference between groups 18·5%, 11·5-25·4, log-rank p<0·0001). Multivariable analyses showed that event-free survival was affected by treatment group, presence of bulky disease, and age-adjusted IPI and that overall survival was affected by treatment group and presence of bulky disease only. After chemotherapy and rituximab, a favourable subgroup (IPI=0, no bulk) could be defined from a less favourable subgroup (IPI=1 or bulk, or both; event-free survival 84·3% [95% CI 74·2-90·7] vs 71·0% [65·1-76·1], log-rank p=0·005). 18 (4·4%, 95% CI 2·6-6·9) second malignancies occurred in the chemotherapy-alone group and 16 (3·9%, 2·2-6·2) in the chemotherapy and rituximab group (Fisher's exact p=0·730).

INTERPRETATION

Rituximab added to six cycles of CHOP-like chemotherapy improved long-term outcomes for young patients with good-prognosis diffuse large-B-cell lymphoma. The definition of two prognostic subgroups allows a more refined therapeutic approach to these patients than does assessment by IPI alone.

FUNDING

Hoffmann-La Roche.

Evaluation of new platinum-based treatment regimens in advanced-stage ovarian cancer: a Phase III Trial of the Gynecologic Cancer Intergroup

PURPOSE

To determine if incorporation of an additional cytotoxic agent improves overall survival (OS) and progression-free survival (PFS) for women with advanced-stage epithelial ovarian carcinoma (EOC) and primary peritoneal carcinoma who receive carboplatin and paclitaxel.

PATIENTS AND METHODS

Women with stages III to IV disease were stratified by coordinating center, maximal diameter of residual tumor, and intent for interval cytoreduction and were then randomly assigned among five arms that incorporated gemcitabine, methoxypolyethylene glycosylated liposomal doxorubicin, or topotecan compared with carboplatin and paclitaxel. The primary end point was OS and was determined by pairwise comparison to the reference arm, with a 90% chance of detecting a true hazard ratio of 1.33 that limited type I error to 5% (two-tail) for the four comparisons.

RESULTS

Accrual exceeded 1,200 patients per year. An event-triggered interim analysis occurred after 272 events on the reference arm, and the study closed with 4,312 women enrolled. Arms were well balanced for demographic and prognostic factors, and 79% of patients completed eight cycles of therapy. There were no improvements in either PFS or OS associated with any experimental regimen. Survival analyses of groups defined by size of residual disease also failed to show experimental benefit in any subgroup.

CONCLUSION

Compared with standard paclitaxel and carboplatin, addition of a third cytotoxic agent provided no benefit in PFS or OS after optimal or suboptimal cytoreduction. Dual-stage, multiarm, phase III trials can efficiently evaluate multiple experimental regimens against a single reference arm. The development of new interventions beyond surgery and conventional platinum-based chemotherapy is required to additionally improve outcomes for women with advanced EOC.

Randomized phase III study of pegylated liposomal doxorubicin plus bortezomib compared with bortezomib alone in relapsed or refractory multiple myeloma: combination therapy improves time to progression

PURPOSE

This phase III international study compared the efficacy and safety of a combination of pegylated liposomal doxorubicin (PLD) plus bortezomib with bortezomib monotherapy in patients with relapsed or refractory multiple myeloma.

PATIENTS AND METHODS

Six hundred forty-six patients were randomly assigned to receive either intravenous bortezomib 1.3 mg/m(2) on days 1, 4, 8, and 11 of an every 21-days cycle, or the same bortezomib regimen with PLD 30 mg/m(2) on day 4.

RESULTS

Median time to progression was increased from 6.5 months for bortezomib to 9.3 months with the PLD + bortezomib combination (P = .000004; hazard ratio, 1.82 [monotherapy v combination therapy]; 95% CI, 1.41 to 2.35). The 15-month survival rate for PLD + bortezomib was 76% compared with 65% for bortezomib alone (P = .03). The complete plus partial response rate was 41% for bortezomib and 44% for PLD + bortezomib, a difference that was not statistically significant. Median duration of response was increased from 7.0 to 10.2 months (P = .0008) with PLD + bortezomib. Grade 3/4 adverse events were more frequent in the combination group (80% v 64%), with safety profiles consistent with the known toxicities of the two agents. An increased incidence in the combination group was seen of grade 3/4 neutropenia, thrombocytopenia, asthenia, fatigue, diarrhea, and hand-foot syndrome.

CONCLUSION

PLD with bortezomib is superior to bortezomib monotherapy for the treatment of patients with relapsed or refractory multiple myeloma. The combination therapy is associated with a higher incidence of grade 3/4 myelosuppression, constitutional symptoms, and GI and dermatologic toxicities.

A single dose of doxorubicin-functionalized bow-tie dendrimer cures mice bearing C-26 colon carcinomas

The antitumor effect of doxorubicin (DOX) conjugated to a biodegradable dendrimer was evaluated in mice bearing C-26 colon carcinomas. An asymmetric biodegradable polyester dendrimer containing 8-10 wt % DOX was prepared. The design of the dendrimer carrier optimized blood circulation time through size and molecular architecture, drug loading through multiple attachment sites, solubility through PEGylation, and drug release through the use of pH-sensitive hydrazone linkages. In culture, dendrimer-DOX was >10 times less toxic than free DOX toward C-26 colon carcinoma cells after exposure for 72 h. Upon i.v. administration to BALB/c mice with s.c. C-26 tumors, dendrimer-DOX was eliminated from the serum with a half-life of 16 +/- 1 h, and its tumor uptake was ninefold higher than i.v. administered free DOX at 48 h. In efficacy studies performed with BALB/c mice bearing s.c. C-26 tumors, a single i.v. injection of dendrimer-DOX at 20 mg/kg DOX equivalents 8 days after tumor implantation caused complete tumor regression and 100% survival of the mice over the 60-day experiment. No cures were achieved in tumor-implanted mice treated with free DOX at its maximum tolerated dose (6 mg/kg), drug-free dendrimer, or dendrimer-DOX in which the DOX was attached by means of a stable carbamate bond. The antitumor effect of dendrimer-DOX was similar to that of an equimolar dose of liposomal DOX (Doxil). The remarkable antitumor activity of dendrimer-DOX results from the ability of the dendrimer to favorably modulate the pharmacokinetics of attached DOX.

Phase I clinical trial and pharmacokinetic evaluation of NK911, a micelle-encapsulated doxorubicin

NK911 is a novel supramolecular nanocarrier designed for the enhanced delivery of doxorubicin (DXR) and is one of the successful polymer micelle systems to exhibit an efficient accumulation in solid tumours in mice. The purpose of this study was to define the maximum-tolerated dose (MTD) and dose-limiting toxicities (DLTs) of NK911 and to evaluate its pharmacokinetic profile in man. NK911 was given intravenously to patients with solid tumours every 3 weeks using an infusion pump at a rate of 10 mg DXR equivalent min⁻¹. The starting dose was 6 mg DXR equivalent m⁻², and the dose was escalated according to the accelerated titration method. A total of 23 patients participated in this study. Neutropenia was the predominant haematological toxicity, and grade 3 or 4 neutropenia was observed at doses of 50 and 67 mg m⁻². Common nonhaematological toxicities were mild alopecia, stomatitis, and anorexia. In the dose identification part of the study, DLTs were observed at a dose of 67 mg m⁻² (grade 4 neutropenia lasting more than 5 days). Thus, this dosage level was determined to be the MTD. Infusion-related reactions were not observed in any cases. The C_5 min and area under the concentration curve parameters of NK911 exhibited dose-dependent characteristics. Among the 23 patients, a partial response was obtained in one patient with metastatic pancreatic cancer. NK911 was well tolerated and produced only moderate nausea and vomiting at myelosuppressive dosages. The recommended phase II dose was determined to be 50 mg m⁻² every 3 weeks.

Development of the polymer micelle carrier system for doxorubicin

We show the result of pre-clinical study of NK911, a polymeric micelle carrier system for doxorubicin (DOX). The NK911 micelle carrier consists of polyethyleneglycol and conjugated doxorubicin-polyaspartic acid. It has high hydrophobic inner core, and therefore can entrap the sufficient amount of DOX. NK911 has a small particle size of about 40 nm in diameter that accumulates in tumor tissue by EPR effect showing much stronger activity than the free DOX. We plan to perform a clinical trial at National Cancer Center Hospital, Japan from 2001.

RGD-based strategies for selective delivery of therapeutics and imaging agents to the tumour vasculature

During the past decade, RGD-peptides have become a popular tool for the targeting of drugs and imaging agents to alphavbeta3-integrin expressing tumour vasculature. RGD-peptides have been introduced by recombinant means into therapeutic proteins and viruses. Chemical means have been applied to couple RGD-peptides and RGD-mimetics to liposomes, polymers, peptides, small molecule drugs and radiotracers. Some of these products show impressive results in preclinical animal models and a RGD targeted radiotracer has already successfully been tested in humans for the visualization of alphavbeta3-integrin, which demonstrates the feasibility of this approach. This review will summarize the structural requirements for RGD-peptides and RGD-mimetics as ligands for alphavbeta3. We will show how they have been introduced in the various types of constructs by chemical and recombinant techniques. The importance of multivalent RGD-constructs for high affinity binding and internalization will be highlighted. Furthermore the in vitro and in vivo efficacy of RGD-targeted therapeutics and diagnostics reported in recent years will be reviewed.

The dose threshold for nanoparticle tumour delivery

Nanoparticle delivery to solid tumours over the past ten years has stagnated at a median of 0.7% of the injected dose. Varying nanoparticle designs and strategies have yielded only minor improvements. Here we discovered a dose threshold for improving nanoparticle tumour delivery: 1 trillion nanoparticles in mice. Doses above this threshold overwhelmed Kupffer cell uptake rates, nonlinearly decreased liver clearance, prolonged circulation and increased nanoparticle tumour delivery. This enabled up to 12% tumour delivery efficiency and delivery to 93% of cells in tumours, and also improved the therapeutic efficacy of Caelyx/Doxil. This threshold was robust across different nanoparticle types, tumour models and studies across ten years of the literature. Our results have implications for human translation and highlight a simple, but powerful, principle for designing nanoparticle cancer treatments.

Randomized phase III trial of gemcitabine compared with pegylated liposomal doxorubicin in patients with platinum-resistant ovarian cancer

PURPOSE

Ovarian cancer (OC) patients experiencing progressive disease (PD) within 6 months of platinum-based therapy in the primary setting are considered platinum resistant (Pt-R). Currently, pegylated liposomal doxorubicin (PLD) is a standard of care for treatment of recurrent Pt-R disease. On the basis of promising phase II results, gemcitabine was compared with PLD for efficacy and safety in taxane-pretreated Pt-R OC patients.

PATIENTS AND METHODS

Patients (n = 195) with Pt-R OC were randomly assigned to either gemcitabine 1,000 mg/m2 (days 1 and 8; every 21 days) or PLD 50 mg/m2 (day 1; every 28 days) until PD or undue toxicity. Optional cross-over therapy was allowed at PD or at withdrawal because of toxicity. Primary end point was progression-free survival (PFS). Additional end points included tumor response, time to treatment failure, survival, and quality of life.

RESULTS

In the gemcitabine and PLD groups, median PFS was 3.6 v 3.1 months; median overall survival was 12.7 v 13.5 months; overall response rate (ORR) was 6.1% v 8.3%; and in the subset of patients with measurable disease, ORR was 9.2% v 11.7%, respectively. None of the efficacy end points showed a statistically significant difference between treatment groups. The PLD group experienced significantly more hand-foot syndrome and mucositis; the gemcitabine group experienced significantly more constipation, nausea/vomiting, fatigue, and neutropenia but not febrile neutropenia.

CONCLUSION

Although this was not designed as an equivalency study, gemcitabine and PLD seem to have a comparable therapeutic index in this population of Pt-R taxane-pretreated OC patients. Single-agent gemcitabine may be an acceptable alternative to PLD for patients with Pt-R OC.

Tumor cell-derived exosomes home to their cells of origin and can be used as Trojan horses to deliver cancer drugs

Cancer is the second leading cause of death worldwide and patients are in urgent need of therapies that can effectively target cancer with minimal off-target side effects. Exosomes are extracellular nano-shuttles that facilitate intercellular communication between cells and organs. It has been established that tumor-derived exosomes contain a similar protein and lipid composition to that of the cells that secrete them, indicating that exosomes might be uniquely employed as carriers for anti-cancer therapeutics. Methods: We isolated exosomes from two cancer cell lines, then co-cultured each type of cancer cells with these two kinds of exosomes and quantified exosome. HT1080 or Hela exosomes were systemically injected to Nude mice bearing a subcutaneous HT1080 tumor to investigate their cancer-homing behavior. Moreover, cancer cell-derived exosomes were engineered to carry Doxil (a common chemotherapy drug), known as D-exo, were used to detect their target and therapeutic efficacy as anti-cancer drugs. Exosome proteome array analysis were used to reveal the mechanism underly this phenomenon. Results: Exosomes derived from cancer cells fuse preferentially with their parent cancer cells, in vitro. Systemically injected tumor-derived exosomes home to their original tumor tissues. Moreover, compared to Doxil alone, the drug-loaded exosomes showed enhanced therapeutic retention in tumor tissues and eradicated them more effectively in nude mice. Exosome proteome array analysis revealed distinct integrin expression patterns, which might shed light on the underlying mechanisms that explain the exosomal cancer-homing behavior. Conclusion: Here we demonstrate that the exosomes' ability to target the parent cancer is a phenomenon that opens up new ways to devise targeted therapies to deliver anti-tumor drugs.

Phase I dose escalation and pharmacokinetic study of pluronic polymer-bound doxorubicin (SP1049C) in patients with advanced cancer

SP1049C is a novel anticancer agent containing doxorubicin and two nonionic pluronic block copolymers. In preclinical studies, SP1049C demonstrated increased efficacy compared to doxorubicin. The objectives of this first phase I study were to determine the toxicity profile, dose-limiting toxicity, maximum tolerated dose and pharmacokinetic profile of SP1049C, and to document any antitumour activity. The starting dose was 5 mg m⁻² (doxorubicin content) as an intravenous infusion once every 3 weeks for up to six cycles. A total of 26 patients received 78 courses at seven dose levels. The dose-limiting toxicity was myelosuppression and DLT was reached at 90 mg m⁻². The maximum tolerated dose was 70 mg m⁻² and is recommended for future trials. The pharmacokinetic profile of SP1049C showed a slower clearance than has been reported for conventional doxorubicin. Evidence of antitumour activity was seen in some patients with advanced resistant solid tumours. Phase II trials with this agent are now warranted to further define its antitumour activity and safety profile.

In Vivo Biomolecule Corona around Blood-Circulating, Clinically Used and Antibody-Targeted Lipid Bilayer Nanoscale Vesicles

The adsorption of proteins and their layering onto nanoparticle surfaces has been called the "protein corona". This dynamic process of protein adsorption has been extensively studied following in vitro incubation of many different nanoparticles with plasma proteins. However, the formation of protein corona under dynamic, in vivo conditions remains largely unexplored. Extrapolation of in vitro formed protein coronas to predict the fate and possible toxicological burden from nanoparticles in vivo is of great interest. However, complete lack of such direct comparisons for clinically used nanoparticles makes the study of in vitro and in vivo formed protein coronas of great importance. Our aim was to study the in vivo protein corona formed onto intravenously injected, clinically used liposomes, based on the composition of the PEGylated liposomal formulation that constitutes the anticancer agent Doxil. The formation of in vivo protein corona was determined after the recovery of the liposomes from the blood circulation of CD-1 mice 10 min postinjection. In comparison, in vitro protein corona was formed by the incubation of liposomes in CD-1 mouse plasma. In vivo and in vitro formed protein coronas were compared in terms of morphology, composition and cellular internalization. The protein coronas on bare (non-PEGylated) and monoclonal antibody (IgG) targeted liposomes of the same lipid composition were also comparatively investigated. A network of linear fibrillary structures constituted the in vitro formed protein corona, whereas the in vivo corona had a different morphology but did not appear to coat the liposome surface entirely. Even though the total amount of protein attached on circulating liposomes correlated with that observed from in vitro incubations, the variety of molecular species in the in vivo corona were considerably wider. Both in vitro and in vivo formed protein coronas were found to significantly reduce receptor binding and cellular internalization of antibody-conjugated liposomes; however, the in vivo corona formation did not lead to complete ablation of their targeting capability.

New intra-arterial drug delivery system for the treatment of liver cancer: preclinical assessment in a rabbit model of liver cancer

BACKGROUND

In the fight against cancer, new drug delivery systems are attractive to improve drug targeting of tumors, maximize drug potency, and minimize systemic toxicity. We studied a new drug delivery system comprising microspheres, with unique properties allowing delivery of large amounts of drugs to tumors for a prolonged time, thereby decreasing plasma levels. Liver tumors, unlike nontumorous liver, draw most of their blood supply from the hepatic artery. Exploiting this property, we delivered drug-eluting microspheres/beads (DEB) loaded with doxorubicin, intra-arterially, in an animal model of liver cancer (Vx-2).

PURPOSE

The purpose of our study was to determine the pharmacokinetics and tumor-killing efficacy of DEB.

RESULTS

Our results show that plasma concentration of doxorubicin was minimal in the animals treated with DEB at all time points (0.009-0.05 micromol/L), suggesting high tumor retention of doxorubicin. This was significantly lower (70-85% decrease in plasma concentration) than control animals treated with doxorubicin intra-arterially. Within the tumor, doxorubicin concentration peaked at 3 days (413.5 nmol/g), remaining high to 7 days (116.7 nmol/g) before declining at 14 days (41.76 nmol/g), indicating continuous doxorubicin elution from beads. In control animals, peak tumor concentration of doxorubicin was 0.09 nmol/g. Tumor necrosis (approaching 100%) was greatest at 7 days, with minimal adverse local side effects reflected in liver function tests results. The plasma concentration of doxorubicinol (doxorubicin main metabolite) was minimal.

CONCLUSIONS

Our results support the concept of DEBs as an effective way to deliver drugs to tumor. This new technology may prove to be a useful weapon against liver cancer.

Doxorubicin cardiotoxicity may be caused by its metabolite, doxorubicinol

Doxorubicin (former generic name, adriamycin), a highly effective anticancer drug, produces cardiotoxicity, which limits its therapeutic potential. The mechanism of this cardiotoxicity has remained elusive. Our data suggest that this toxicity could involve doxorubicinol, the primary circulating metabolite of doxorubicin. Doxorubicinol was markedly more potent than doxorubicin at compromising both systolic and diastolic cardiac function. Similarly, doxorubicinol was much more potent than doxorubicin at inhibiting the calcium pump of sarcoplasmic reticulum [ATP phosphohydrolase (Ca2+-transporting), EC 3.6.1.38], the Na+/K+ pump of sarcolemma [ATP phosphohydrolase (Na+/K+-transporting), EC 3.6.1.37], and the F0F1 proton pump of mitochondria [ATP phosphohydrolase (H+-transporting, EC 3.6.1.34]. Our finding that this highly toxic metabolite was produced by cardiac tissue exposed to doxorubicin suggests that doxorubicinol could accumulate in the heart and contribute significantly to the chronic cumulative cardiotoxicity of doxorubicin therapy. Our observation that doxorubicin was more potent than doxorubicinol in inhibiting tumor cell growth in vitro suggests that the cardiotoxicity of doxorubicin is dissociable from its anticancer activity.

New advances in the transport of doxorubicin through the blood-brain barrier by a peptide vector-mediated strategy

Many therapeutic drugs are excluded from entering the brain, due to their lack of transport through the blood-brain barrier (BBB). To overcome this problem, we have developed a novel method in which short, naturally derived peptides (16-18 amino acids) cross the cellular membranes of the BBB with high efficiency and without compromising its integrity. The antineoplastic agent doxorubicin (dox) was coupled covalently to two peptides, D-penetratin and SynB1. The ability of dox to cross the BBB was studied using an in situ rat brain perfusion technique and also by i.v. injection in mice. In the brain perfusion studies, we first confirmed the very low brain uptake of free radiolabeled dox because of the efflux activity of P-glycoprotein at the BBB. By contrast, we have demonstrated that when dox is coupled to either the D-penetratin or SynB1 vectors, its uptake was increased by a factor of 6, suggesting that the vectorized dox bypasses P-glycoprotein. Moreover, using a capillary depletion method, we have shown that vectorization of dox led to a 20-fold increase in the amount of dox transported into brain parenchyma. Intravenous administration of vectorized dox at a dose of 2.5 mg/kg in mice led to a significant increase in brain dox concentrations during the first 30 min of postadministration, compared with free dox. Additionally, vectorization led to a significant decrease of dox concentrations in the heart. In summary, our results establish that the two peptide vectors used in this study enhance the delivery of dox across the BBB.

Doxorubicin-conjugated biodegradable polymeric micelles having acid-cleavable linkages

Doxorubicin was chemically conjugated to the terminal end of a di-block copolymer composed of poly(L-lactic acid) (PLLA) and methoxy-poly(ethylene glycol) (mPEG) via two acid-cleavable linkages. A hydrazone bond and a cis-acotinyl bond were formed between doxorubicin and the terminal group of PLLA segment in the block copolymer. Doxorubicin-conjugated PLLA-mPEG di-block copolymers self-assembled to form micelles in aqueous solution. The doxorubicin-conjugated micelles were about 89.1 nm in diameter and their critical micelle concentration was 1.3 microg/ml. These values were comparable with those of unconjugated micelles. In an acidic condition, the conjugated doxorubicin in the hydrazone linkage was readily cleaved, releasing doxorubicin in an intact structure. Doxorubicin-conjugated PLLA-mPEG micelles were more potent in cell cytotoxicity than free doxorubicin, suggesting that they were more easily taken up within cells with concomitant rapid release of cleaved doxorubicin into the cytoplasm from acidic endosomes.

Evidence of a specific complex between adriamycin and negatively-charged phospholipids

Membrane-model systems (monolayers, small unilamellar vesicles) were used to study the interaction between adriamycin (ADM) and phospholipids. Adsorption of 3H-labeled adriamycin on different phospholipid monolayers demonstrated the specificity of adriamycin for negatively-charged phospholipids (cardiolipin, phosphatidylserine, phosphatidic acid). The stoichiometry has been found to be approx. 2 mol (1.8) adriamycin per mol cardiolipin and approx. 1 mol (0.75) adriamycin per mol phosphatidylserine and phosphatidic acid. No adsorption was detected with neutral lipids. Surface-potential measurements confirm the formation of a complex stabilized by electrostatic interactions without penetration of the drug into the lipid lipophilic phase. Some adriamycin derivatives were used to discriminate between the ionized hydrophilic and hydrophobic contributions in the complex formation. The absorption spectrum of adriamycin in the presence of cardiolipin resembles the behavior of the ADM-DNA complex. Moreover, the association constants of the two complexes are very similar (cardiolipin-ADM, 1.6 . 10(6) . M-1; ADM-DNA, 2.4 . 10(6) . M-1). To explain the high affinity of cardiolipin for adriamycin, we proposed that two essential interactions are responsible for the complex stabilization: an electrostatic interaction between the protonated amino groups of the sugar residues and the ionized phosphate residues, and an interaction between adjacent anthraquinone chromophores. These data strongly suggest competitive behavior between a membrane site and the target. Consequently, it must be assumed that the lipidic components of the cell membrane structure may be an important determinant in the behavior of adriamycin. This observation should be kept in mind in the building of new derivatives.

Spin-trapping and direct electron spin resonance investigations of the redox metabolism of quinone anticancer drugs

The superoxide free radical has been spin trapped in microsomal incubations containing adriamycin, daunorubicin, and mitomycin C. The time sequence of the appearance of the spin-trapped superoxide and the semiquinone radical metabolite of these quinone-containing anticancer drugs indicates that air oxidation of the semiquinone is responsible for the superoxide formation. Superoxide dismutase prevents the formation of the superoxide spin adducts. Microsomal incubations containing anthracyclines intercalated in DNA produce much less superoxide than incubations free of DNA. The first unambiguous ESR evidence for the semiquinone metabolite of mitomycin C in a biological system is also presented.

Probing the cysteine-34 position of endogenous serum albumin with thiol-binding doxorubicin derivatives. Improved efficacy of an acid-sensitive doxorubicin derivative with specific albumin-binding properties compared to that of the parent compound

We have recently proposed a macromolecular prodrug strategy for improved cancer chemotherapy based on two features (Kratz, F.; et al. J. Med. Chem 2000, 43, 1253-1256.): (a) rapid and selective binding of thiol-reactive prodrugs to the cysteine-34 position of endogenous albumin after intravenous administration and (b) release of the albumin-bound drug in the acidic environment at the tumor site due to the incorporation of an acid-sensitive bond between the drug and the carrier. To investigate this therapeutic strategy in greater depth, four (maleinimidoalkanoyl)hydrazone derivatives of doxorubicin were synthesized differing in the length of the aliphatic spacer (1, -(CH(2))(2)-; 2, -(CH(2))(3)-; 3, -(CH(2))(5)-; 4, -(CH(2))(7)-). The albumin-binding doxorubicin prodrugs, especially the (6-maleimidocaproyl)hydrazone derivative of doxorubicin (3), are rapidly and selectively bound to the cysteine-34 position of endogenous albumin. 3 was distinctly superior to the parent compound doxorubicin in three animal tumor models (RENCA, MDA-MB 435, and MCF-7) with respect to antitumor efficacy and toxicity.

Systematic Review and Individual Patient Data Meta-analysis of Randomized Trials Comparing a Single Immediate Instillation of Chemotherapy After Transurethral Resection with Transurethral Resection Alone in Patients with Stage pTa-pT1 Urothelial Carcinoma of the Bladder: Which Patients Benefit from the Instillation?

CONTEXT

The European Association of Urology non-muscle-invasive bladder cancer (NMIBC) guidelines recommend that all low- and intermediate-risk patients receive a single immediate instillation of chemotherapy after transurethral resection of the bladder (TURB), but its use remains controversial.

OBJECTIVE

To identify which NMIBC patients benefit from a single immediate instillation.

EVIDENCE ACQUISITION

A systematic review and individual patient data (IPD) meta-analysis of randomized trials comparing the efficacy of a single instillation after TURB with TURB alone in NMIBC patients was carried out.

EVIDENCE SYNTHESIS

A total of 13 eligible studies were identified. IPD were obtained for 11 studies randomizing 2278 eligible patients, 1161 to TURB and 1117 to a single instillation of epirubicin, mitomycin C, pirarubicin, or thiotepa. A total of 1128 recurrences, 108 progressions, and 460 deaths (59 due to bladder cancer [BCa]) occurred. A single instillation reduced the risk of recurrence by 35% (hazard ratio [HR]: 0.65; 95% confidence interval [CI], 0.58-0.74; p<0.001) and the 5-yr recurrence rate from 58.8% to 44.8%. The instillation did not reduce recurrences in patients with a prior recurrence rate of more than one recurrence per year or in patients with an European Organization for Research and Treatment of Cancer (EORTC) recurrence score ≥5. The instillation did not prolong either the time to progression or death from BCa, but it resulted in an increase in the overall risk of death (HR: 1.26; 95% CI, 1.05-1.51; p=0.015; 5-yr death rates 12.0% vs 11.2%), with the difference appearing in patients with an EORTC recurrence score ≥5.

CONCLUSIONS

A single immediate instillation reduced the risk of recurrence, except in patients with a prior recurrence rate of more than one recurrence per year or an EORTC recurrence score ≥5. It does not prolong either time to progression or death from BCa. The instillation may be associated with an increase in the risk of death in patients at high risk of recurrence in whom the instillation is not effective or recommended.

PATIENT SUMMARY

A single instillation of chemotherapy immediately after resection reduces the risk of recurrence in non-muscle-invasive bladder cancer; however, it should not be given to patients at high risk of recurrence due to its lack of efficacy in this subgroup.

Gemcitabine, vinorelbine, and pegylated liposomal doxorubicin (GVD), a salvage regimen in relapsed Hodgkin's lymphoma: CALGB 59804

BACKGROUND

Because of high single-agent activity and modest toxicity, we hypothesized the combination of gemcitabine (G), vinorelbine (V), and pegylated liposomal doxorubicin (D) would be an effective salvage therapy for Hodgkin's lymphoma (HL).

PATIENTS AND METHODS

A total of 91 patients participated. GVD was administered on days 1 and 8 every 21 days at doses of G 1000 mg/m(2), V 20 mg/m(2), and D 15 mg/m(2) for transplant-naive patients, and G 800 mg/m(2), V 15 mg/m(2), and D 10 mg/m(2) for post-transplant patients.

RESULTS

The dose-limiting toxicity was mucositis for the transplant-naive patients and febrile neutropenia for post-transplant patients. The overall response rate (RR) for all patients was 70% [95% confidence interval (CI) 59.8, 79.7], with 19% complete remissions. The 4-year event-free and overall survival rates in transplant-naive patients treated with GVD followed by autologous transplant were 52% (95% CI 0.34, 0.68) and 70% (95% CI 0.49, 0.84), and in the patients in whom prior transplant failed, these were 10% (95% CI 0.03, 0.22) and 34% (95% CI 0.17, 0.52), respectively.

CONCLUSIONS

GVD is a well-tolerated, active regimen for relapsed HL with results similar to those reported for more toxic regimens. High RRs in patients in whom prior transplant failed confirms this regimen's activity even in heavily pretreated patients.