Isolation of drug delivery from drug effect: problems of optimizing drug delivery parameters

A recurring question in the treatment of malignant brain tumors has been whether treatment failure is due to inadequate delivery or ineffective drugs. To isolate these issues, we tested a paradigm in which the "therapeutic" agent was a toxin about which there could be no question of efficacy, provided it was delivered in adequate amounts; we used 10% formalin. We infused 10% formalin into 5- to 8-mm subcutaneous RG-2 and D54-MG gliomas at increasing rates until we achieved 100% tumor cell kill. In RG-2 gliomas, infusions of 10 microl/h x 7 days, and 2, 4, 6, and 8 microl/min x 2 h failed to kill tumors, although growth was delayed, while infusion rates of 12 microl/min x 60 min and 48 microl/min x 15 min produced 100% tumor kill. In D54-MG tumors, infusions of 4, 8, and 24 microl/min produced 100% tumor kill. 14C-Formalin autoradiographs showed a heterogeneous distribution after infusions of 2 microl/min x 2 h, whereas infusions of 48 microl/min x 15 min showed a homogeneous distribution within the tumor, but more than 95% of tissue radioactivity was found in tissue surrounding tumor. Drug delivery remains a major issue in brain tumor treatment: Distribution inhomogeneity, rapid efflux, and consequent treatment failures are likely due to high interstitial fluid pressure. Because the infusion rates being used in the treatment of human brain tumors are low and the tumors are larger, treatment failures can be expected on the basis of inadequate drug delivery alone, regardless of the effectiveness of the drug.     

E-selectin up-regulation allows for targeted drug delivery in prostate cancer

We have used the Eos Hu03 GeneChip array, which represents over 92% of the transcribed human genome, to measure gene expression in a panel of normal and diseased human tissues. This analysis revealed that E-selectin mRNA is selectively overexpressed in prostate cancer epithelium, a finding that correlated strongly with E-selectin protein expression as assessed by immunohistochemistry. Antibodies against E-selectin that blocked function failed to impede cancer cell growth, suggesting that overexpression of E-selectin was not essential for cell growth. However, a novel auristatin E-based antibody drug conjugate (ADC), E-selectin antibody valine-citrulline monomethyl-auristatin E, was a potent and selective agent against E-selectin-expressing cancer cell lines in vitro, with the degree of cytotoxicity varying with surface antigen density. Interestingly, sensitivity to the ADC differed among cell lines from different tissues expressing similar amounts of E-selectin and was found to correlate with sensitivity to free auristatin E. Furthermore, E-selectin-expressing tumors grown as xenografts in severe combined immunodeficient mice were responsive to treatment with E-selectin antibody valine-citrulline monomethyl-auristatin E in vivo, with more than 85% inhibition of tumor growth observed in treated mice. These findings demonstrate that an E-selectin-targeting ADC has potential as a prostate cancer therapy and validates a genomics-based paradigm for the identification of cancer-specific antigens suitable for targeted therapy.     

Marriage and ethnicity predict treatment in localized prostate carcinoma

BACKGROUND: Primary treatment for early-stage prostate carcinoma includes expectant management or, for curative intent, radical prostatectomy or radiotherapy. Treatment recommendations are generally guided by clinical factors such as Gleason grade, prostate-specific antigen level, comorbid illnesses, and patient age. Sociocultural factors may also have influences on patient and urologist treatment choices. METHODS: The authors used bivariate and multinomial logistic regression to identify medical and sociodemographic predictors of prostatectomy (compared with radiotherapy) and curative therapy (compared with expectant management) in a cohort of 27,920 non-Latino white, black, and Latino men without comorbidities in the latest linked Surveillance, Epidemiology and End Results-Medicare dataset (years 1995-1999). Predictors included tumor stage, patient age, marital status, race/ethnicity, and socioeconomic status. RESULTS: Younger age and higher tumor grade were robust predictors of curative treatment compared with expectant management and of prostatectomy compared with radiotherapy. Sociodemographic factors had an additive role in treatment choice. Marriage predicted curative treatment compared with expectant management (adjusted risk ratio [RR] = 1.28 [1.25-1.30]) and prostatectomy compared with radiotherapy (adjusted RR = 1.24 [1.20-1.28]). Although blacks and Latinos were just as likely as whites to receive curative treatment, blacks were significantly less likely, whereas Latinos were more likely, to receive prostatectomy compared with radiotherapy (adjusted RRs = 0.77 [0.72-83]) and 1.24 [1.18-1.30], respectively). CONCLUSIONS: Marriage was positively associated with curative treatment in general, and with prostatectomy specifically. Blacks received prostatectomy less often than whites, although they did not receive less curative treatment overall. Latinos received prostatectomy more often than whites. Clinicians should recognize the importance of cultural and social forces as well as biomedical factors in decisions regarding the treatment of patients with early-stage prostate carcinoma.     

Liposome-based drug delivery in breast cancer treatment

Drug delivery systems can in principle provide enhanced efficacy and/or reduced toxicity for anticancer agents. Long circulating macromolecular carriers such as liposomes can exploit the 'enhanced permeability and retention' effect for preferential extravasation from tumor vessels. Liposomal anthracyclines have achieved highly efficient drug encapsulation, resulting in significant anticancer activity with reduced cardiotoxicity, and include versions with greatly prolonged circulation such as liposomal daunorubicin and pegylated liposomal doxorubicin. Pegylated liposomal doxorubucin has shown substantial efficacy in breast cancer treatment both as monotherapy and in combination with other chemotherapeutics. Additional liposome constructs are being developed for the delivery of other drugs. The next generation of delivery systems will include true molecular targeting; immunoliposomes and other ligand-directed constructs represent an integration of biological components capable of tumor recognition with delivery technologies.     

Optimization of MVCT imaging schedule in prostate cancer treatment using helical tomotherapy.]

PURPOSE: Megavoltage CT (MVCT) study on helical tomotherapy permits to verify and correct the patient setup by coregistration with the planning kVCT. This process is time-consuming and our objective is to investigate a possibility of using a smaller number of imaging studies in the case of patients with prostate cancer. PATIENTS AND METHODS: The interfraction shifts of 20 patients (about 700 MVCT studies) treated in our institution have been recorded and analyzed. A new reference position has been calculated as an average of shifts observed during different initial number of fractions imaged. RESULTS: The analysis of the reference position obtained for the set of 20 patients as a function of the number of imaging sessions has shown that MVCT studies during first four fractions are sufficient for the majority of patients. CONCLUSION: Imaging during the first four fractions can be used to determine a reference position for patients with prostate cancer treated on helical tomotherapy. A study on Planned Adaptive((R)) (TomoTherapy Inc., Madison, WI, USA) software to evaluate the clinical significance of this scenario is currently in process in our institution.     

Anti-HER2 cationic immunoemulsion as a potential targeted drug delivery system for the treatment of prostate cancer

Present management of metastatic prostate cancer, which includes hormonal therapy, chemotherapy, and radiotherapy, are frequently palliative. Taxanes, and specifically docetaxel, are being extensively investigated to improve the survival of metastatic prostate cancer patients. Although paclitaxel exhibits a wide spectrum of antitumor activity, its therapeutic application is limited, in part, due to its low water solubility that necessitates the use of Cremophor EL, which is known to induce hypersensitivity reactions. Therefore, the objective of this present study was to assess the efficiency of paclitaxel palmitate-loaded anti-HER2 immunoemulsions, a targeted drug delivery system based on cationic emulsion covalently linked to anti-HER2 monoclonal antibody (Herceptin), in a well-established in vivo pharmacologic model of metastatic prostate cancer that overexpresses the HER2 receptor. It was clearly noted that the cationic emulsion and immunoemulsion did not activate the complement compared with the commercial and paclitaxel palmitate hydroalcoholic formulations. In addition, 10 mg/kg of paclitaxel palmitate-loaded immunoemulsion once weekly over 3 weeks inhibits the tumor growth in severe combined immunodeficient mice much more than the cationic emulsion (P < 0.05) and the paclitaxel palmitate formulation (P < 0.01). The histopathologic analysis suggested a therapeutic improvement trend in favor of the immunoemulsion. However, there was no significant difference in antimetastatic activity between the emulsion and the immunoemulsion despite the affinity of the immunoemulsion towards the HER2 receptor. Although the tumor growth was not fully inhibited, the actual results are encouraging and may lead to an improved therapeutic strategy of metastatic prostate cancer treatment.     

Advances in drug delivery and targeting.

This review covers a variety of techniques aimed at improving the specificity of delivery of both biologic and cytotoxic agents to tumor tissue while sparing normal tissue. The major areas reported on include further attempts to increase the ability of monoclonal antibodies, both conjugated and unconjugated, to target tumor tissue. It also examines the early clinical trials of liposomes as carriers of both biologics and cytotoxics and the potential problems of this modality. A number of studies in the area of regional drug delivery, including intraperitoneal, intravesical, intra-arterial, and intratumor, highlight the many clinical problems still to be resolved. Improved targeting of antitumor agents to sites of malignant disease appears likely over the next decade judging by the recent developments we review. Although much clinical and laboratory research will be required to achieve this goal, the likely directions appear to be established.     

Site-specific drug delivery by photochemical internalization enhances the antitumor effect of bleomycin.

PURPOSE: Photochemical internalization is under development for improving macromolecular therapy by inducing photochemical damage to endocytic vesicles. This damage leads to the release of therapeutic macromolecules entrapped in endocytic vesicles into the cytosol. The macromolecules may in this way be able to interact with therapeutic targets instead of being degraded by lysosomal hydrolases. Bleomycin is used in several standard cancer chemotherapy regimens. Its hydrophilic and relatively large chemical structure limits its ability to penetrate membrane structures, which causes the accumulation of bleomycin in endocytic vesicles. The purpose of this study was to evaluate the therapeutic potential of aluminum phthalocyanine disulfonate (AlPcS2a)-based photochemical delivery of bleomycin. EXPERIMENTAL DESIGN: Three tumors of different origin were grown s.c. in BALB/c (nu/nu) mice. The photosensitizer AlPcS2a and bleomycin were systemically administered and the tumor area was exposed to red light when the tumor volume had reached 100 mm3. The tumor volume was measured frequently after treatment and the time for the tumor volume to reach 800 to 1,000 mm3 was selected as the end point. RESULTS: The photochemical delivery of bleomycin induced a delayed tumor regrowth, and in two out of three tumor models, lead to 60% complete response, whereas no complete responses were seen after treatment with bleomycin alone. A statistical model to assess synergism was established. Combination of the photochemical treatment and bleomycin was found to induce a synergistic delay in tumor growth. CONCLUSION: AlPcS2a-based photochemical internalization of bleomycin induces a synergistic inhibition of tumor growth in three different tumor models. This treatment combination should be further considered for clinical utilization.     

Dependence of 1,2-dimethylhydrazine metabolism on its treatment schedule.

The content of cytochromes P-450 and b5 in rat liver microsomes, as well as the extent of labeling of nucleic acids and proteins of the liver and kidneys and of mucosa from different intestinal segments, was studied in rats injected daily or once a week subcutaneously with similar total doses of 1,2-dimethyl-hydrazine (SDMH) and in untreated rats. Daily SDMH administrations led to a decrease in cytochrome P-450 activity. Pretreatment of rats with unlabelled SDMH resulted in decreased labeling of DNA, RNA, proteins, and acid-soluble fractions after [3H]SDMH injection. A more pronounced effect was found after the daily treatment.     

The effect of patient position and treatment technique in conformal treatment of prostate cancer.

PURPOSE: The relative value of prone versus supine positioning and axial versus nonaxial beam arrangements in the treatment of prostate cancer remains controversial. Two critical issues in comparing techniques are: 1) dose to critical normal tissues, and 2) prostate stabilization. METHODS AND MATERIALS: Ten patients underwent pretreatment CT scans in one supine and two prone positions (flat and angled). To evaluate normal tissue exposure, prostate/seminal vesicle volumes or prostate volumes were expanded 8 mm and covered by the 95% isodose surface by both 6-field axial and 4-field nonaxial techniques. A total of 280 dose-volume histograms (DVHs) were analyzed to evaluate dose to rectal wall and bladder relative to patient position and beam arrangement. A CT scan was repeated in each patient after 5 weeks of treatment. Prostate motion was assessed by comparing early to late scans by three methods: 1) center of mass shift, 2) superior pubic symphysis to anterior prostate distance, and 3) deviation of the posterior surface of the prostate. RESULTS: For prostate (P) or prostate/seminal vesicle (P/SV) treatments, prone flat was advantageous or equivalent to other positions with regard to rectal sparing. The mechanism of rectal sparing in the prone position may be related to a paradoxical retraction of the rectum against the sacrum, away from the P/SV. Although there was no clear overall preference for beam arrangement, substantial improvements in rectal sparing could be realized for individual patients. In this limited number of patients, there was no convincing evidence prostate position was stabilized by prone relative to supine position. CONCLUSIONS: Prone flat positioning was advantageous over other positions and beam arrangements in rectal sparing. This study suggests that patient position is a more critical a factor in conformal therapy than beam arrangement, and may improve the safety of dose escalation.     

Treatment of Hodgkin's disease with MOPP chemotherapy: effect of dose and schedule modification on treatment outcome.

An analysis of the therapy details of 99 patients receiving primary MOPP chemotherapy for Hodgkin's disease revealed that treatment modification was a frequent occurrence. The mean cumulative dose calculated as a percentage of the projected ideal dose was 76%. Dose modifications of individual components of the MOPP combination were, however, variable and in part reflected disease-related factors, e.g. patients with stage 4 disease received significantly less vincristine than those with less advanced disease. An initial univariate analysis of factors influencing remission showed that the remission rate was significantly lower among those patients who had (a) liver involvement and (b) drug doses less than 75% of the ideal cumulative dose. Among the individual drug dosages, modification of the vincristine dose appeared to be the most significant treatment-related factor associated with lower remission rates. In a multivariate analysis where both disease-related and treatment-related factors were taken into account drug dosage remained a significant prognostic factor. The most important factors adversely affecting initial remission were the presence of liver involvement and reduction of the drug intensity index (cumulative dose divided by cumulative time). Disease-free survival was adversely influenced mainly by the presence of B symptoms and to a lesser degree, but still significantly, by a lower cumulative vincristine dose. Total survival was, however, influenced adversely only by the presence of B symptoms. The quality of MOPP therapy appears to play a significant role in determining the outcome of Hodgkin's disease.     

Novel advances in drug delivery to brain cancer

The therapy of brain tumors has been limited by a lack of effective methods of drug delivery to the brain. Systemic administration is often associated with toxic side effects and ultimately fails to achieve therapeutic concentrations within a tumor. An attractive strategy that has gained importance in brain tumor therapy has relied on local and controlled delivery of chemotherapeutic agents by biodegradable polymers. This technique allows direct exposure of tumor cells to a therapeutic agent for a prolonged period of time and has been shown to prolong the survival of patients with malignant brain tumors. The use of polymers for local drug delivery greatly expands the spectrum of drugs available for the treatment of malignant brain tumors. This review discusses the rationale for local drug delivery, describes the development of currently available polymer-based therapeutic agents, and highlights examples of promising non-polymer based drug delivery methods for use in the treatment of malignant brain tumors.     

Circulating tumor cells predict survival benefit from treatment in metastatic castration-resistant prostate cancer

PURPOSE: A method for enumerating circulating tumor cells (CTC) has received regulatory clearance. The primary objective of this prospective study was to establish the relationship between posttreatment CTC count and overall survival (OS) in castration-resistant prostate cancer (CRPC). Secondary objectives included determining the prognostic utility of CTC measurement before initiating therapy, and the relationship of CTC to prostate-specific antigen (PSA) changes and OS at these and other time points. EXPERIMENTAL DESIGN: Blood was drawn from CRPC patients with progressive disease starting a new line of chemotherapy before treatment and monthly thereafter. Patients were stratified into predetermined Favorable or Unfavorable groups (<5 and > or =5 CTC/7.5mL). RESULTS: Two hundred thirty-one of 276 enrolled patients (84%) were evaluable. Patients with Unfavorable pretreatment CTC (57%) had shorter OS (median OS, 11.5 versus 21.7 months; Cox hazard ratio, 3.3; P < 0.0001). Unfavorable posttreatment CTC counts also predicted shorter OS at 2 to 5, 6 to 8, 9 to 12, and 13 to 20 weeks (median OS, 6.7-9.5 versus 19.6-20.7 months; Cox hazard ratio, 3.6-6.5; P < 0.0001). CTC counts predicted OS better than PSA decrement algorithms at all time points; area under the receiver operator curve for CTC was 81% to 87% and 58% to 68% for 30% PSA reduction (P = 0.0218). Prognosis for patients with (a) Unfavorable baseline CTC who converted to Favorable CTC improved (6.8 to 21.3 months); (b) Favorable baseline CTC who converted to Unfavorable worsened (>26 to 9.3 months). CONCLUSIONS: CTC are the most accurate and independent predictor of OS in CRPC. These data led to Food and Drug Administration clearance of this assay for the evaluation of CRPC.     

Serum microRNA expression patterns that predict early treatment failure in prostate cancer patients

We aimed to identify microRNA (miRNA) expression patterns in the serum of prostate cancer (CaP) patients that predict the risk of early treatment failure following radical prostatectomy (RP). Microarray and Q-RT-PCR analyses identified 43 miRNAs as differentiating disease stages within 14 prostate cell lines and reflectedpublically available patient data. 34 of these miRNA were detectable in the serum of CaP patients. Association with time to biochemical progression was examined in a cohort of CaP patients following RP. A greater than two-fold increase in hazard of biochemical progression associated with altered expression of miR-103, miR-125b and miR-222 (p <.0008) in the serum of CaP patients. Prediction models based on penalized regression analyses showed that the levels of the miRNAs and PSA together were better at detecting false positives than models without miRNAs, for similar level of sensitivity. Analyses of publically available data revealed significant and reciprocal relationships between changes in CpG methylation and miRNA expression patterns suggesting a role for CpG methylation to regulate miRNA. Exploratory validation supported roles for miR-222 and miR-125b to predict progression risk in CaP. The current study established that expression patterns of serum-detectable miRNAs taken at the time of RP are prognostic for men who are at risk of experiencing subsequent early biochemical progression. These non-invasive approaches could be used to augment treatment decisions.     

Computational modeling and experimental evaluation of a novel prodrug for targeting the extracellular space of prostate tumors

We are developing a noninvasive approach for targeting imaging and therapeutic radionuclides to prostate cancer. Our method, Enzyme-Mediated Cancer Imaging and Therapy (EMCIT), aims to use enzyme-dependent, site-specific, in vivo precipitation of a radioactive molecule within the extracellular space of solid tumors. Advanced methods for data mining of the literature, protein databases, and knowledge bases (IT.Omics LSGraph and Ingenuity Systems) identified prostatic acid phosphatase (PAP) as an enzyme overexpressed in prostate cancer and secreted in the extracellular space. Using AutoDock 3.0 software, the prodrug ammonium 2-(2'-phosphoryloxyphenyl)-6-iodo-4-(3H)-quinazolinone (IQ(2-P)) was docked in silico into the X-ray structure of PAP. The data indicate that IQ(2-P) docked into the PAP active site with a calculated inhibition constant (K(i)) more favorable than that of the PAP inhibitor alpha-benzylaminobenzylphosphonic acid. When (125)IQ(2-P), the radioiodinated form of the water-soluble prodrug, was incubated with PAP, rapid hydrolysis of the compound was observed as exemplified by formation of the water-insoluble 2-(2'-hydroxyphenyl)-6-[(125)I]iodo-4-(3H)-quinazolinone ((125)IQ(2-OH)). Similarly, the incubation of IQ(2-P) with human LNCaP, PC-3, and 22Rv1 prostate tumor cells resulted in the formation of large fluorescent IQ(2-OH) crystals. No hydrolysis was seen in the presence of normal human cells. Autoradiography of tumor cells incubated with (125)IQ(2-P) showed accumulation of radioactive grains ((125)IQ(2-OH)) around the cells. We anticipate that the EMCIT approach will enable the active in vivo entrapment of radioimaging and radiotherapeutic compounds within the extracellular spaces of primary prostate tumors and their metastases.     

Immunologic approaches to the treatment of prostate cancer.

The presence of several organ-specific molecules that could serve as immunogens or targets of an immune attack, the nonessential nature of the prostate gland, the substantial failure rate after treatment of the primary tumor, and the lack of effective chemotherapy for metastatic disease make prostate cancer an ideal candidate for immunotherapy. This report reviews the current status of two novel approaches to the treatment of prostate cancer. The first is an effort to induce antitumor immunity by enriching the cytokine environment within the primary cancer by intraprostatic injection of Leukocyte Interleukin (Cel-Sci Corp, Vienna, VA), a mixture of natural cytokines that includes interleukin-1 beta (IL-1beta), IL-2, granulocyte-macrophage colony-stimulating factor (GM-CSF), interferon gamma (IFN-gamma), and tumor necrosis factor alpha (TNF-alpha). The second approach uses OncoVax-P (Jenner Biotherapies, Inc, San Ramon, CA), a vaccine consisting of liposome-encapsulated recombinant prostate-specific antigen (PSA) and lipid A. When administered as an emulsion or in association with bacillus Calmette-Guérin (BCG)/cyclophosphamide or GM-CSF with or without IL-2/cyclophosphamide, immunologic tolerance is broken as evidenced by the generation of humoral and cellular immunity. Both of these approaches have been shown to be feasible and safe, and are now being tested in patients with less advanced disease to determine if manipulation of the immune system can favorably influence clinical outcome.     

Risk profiles to predict PSA relapse-free survival for patients undergoing permanent prostate brachytherapy.

PURPOSE: Combined risk profiles are helpful in assessing the likelihood of prostate-specific antigen relapse-free survival (PSA-RFS) for patients with localized prostate cancer. This retrospective analysis reports the 5-year biochemical outcome of a large cohort of patients according to prognostic factors and risk profiles for patients undergoing ultrasound-guided transperineal interstitial permanent prostate brachytherapy (TIPPB). PATIENTS AND METHODS: Seven hundred seventeen consecutive patients with clinically localized prostate cancer treated between June 1992 and November 1997 underwent TIPPB. Palladium-103 (103Pd) (n = 539) or iodine-125 (125I) (n = 178) sources were utilized to a prescribed dose of 120 Gy and 144 Gy, respectively. One hundred eleven patients received combined external-beam irradiation (41.4 or 45 Gy) and TIPPB (103Pd, 90 Gy, and 125I, 108 Gy). One hundred twelve patients received androgen ablation therapy in advance of TIPPB. Patients were grouped into risk profiles based on pretreatment factors that consisted of PSA < or = 10 and Gleason score < or = 6. Patients meeting both criteria were classified as favorable (n = 334). Those not fulfilling one criteria were classified as intermediate risk (n = 261), and those not fulfilling two criteria were classified as unfavorable risk (n = 261). PSA-RFS was calculated based on the American Society of Therapeutic Radiology and Oncology consensus conference definition of PSA failure. The median follow-up was 41 months (range, 14-82 months). RESULTS: The actuarial PSA-RFS survival at 5 years was 82%. Multivariate Cox regression analysis identified PSA and Gleason score as highly significant factors predicting for biochemical outcome. Hazard risk ratios using a nadir definition of the PSA as < or = 1.0 ng/mL and < or = 0.5 ng/mL were each significant predictors of outcome with the 0.5 ng/mL nadir level only slightly better (risk ratio for nadir < or = 1.0 = 2.78; risk ratio for nadir < or = 0.5 = 3.57). Favorable-risk patients had a 5-year actuarial PSA-RFS of 93%, whereas intermediate-risk and unfavorable-risk groups had 5-year PSA-RFSs of 77% and 62%, respectively. Four hundred ninety-three patients underwent brachytherapy without external-beam irradiation or androgen ablation. From this group, the 5-year PSA-RFSs for the favorable-risk, intermediate-risk, and unfavorable-risk patients were 92%, 74%, and 55%, respectively. DISCUSSION: This retrospective study examining TIPPB demonstrated excellent 5-year actuarial PSA-RFS rates. The assignment of risk profiles based on the results of multivariate analysis of prognostic factors identifies the expected PSA-RFS for patients undergoing TIPPB.