Tumor targeting by conjugation of DHA to paclitaxel

Targeting an anti-cancer drug to tumors should increase the Area Under the drug concentration-time Curve (AUC) in tumors while decreasing the AUC in normal cells and should therefore increase the therapeutic index of that drug. Anti-tumor drugs typically have half-lives far shorter than the cell cycle transit times of most tumor cells. Tumor targeting, with concomitant long tumor exposure times, will increase the proportion of cells that move into cycle when the drug concentration is high, which should result in more tumor cell killing. In an effort to test that hypothesis, we conjugated a natural fatty acid, docosahexaenoic acid (DHA), through an ester bond to the paclitaxel 2'-oxygen. The resulting paclitaxel fatty acid conjugate (DHA-paclitaxel) does not assemble microtubules and is non-toxic. In the M109 mouse tumor model, DHA-paclitaxel is less toxic than paclitaxel and cures 10/10 tumored animals, whereas paclitaxel cures 0/10. One explanation for the conjugate's greater therapeutic index is that the fatty acid alters the pharmacokinetics of the drug to increase its AUC in tumors and decrease its AUC in normal cells. To test that possibility, we compared the pharmacokinetics of DHA-paclitaxel with paclitaxel in CD2F1 mice bearing approximately 125 mg sc M109 tumors. The mice were injected at zero time with a bolus of either DHA-paclitaxel or paclitaxel formulated in 10% cremophor/10% ethanol/80% saline. Animals were sacrificed as a function of time out to 14 days. Tumors and plasma were frozen and stored. The concentrations of paclitaxel and DHA-paclitaxel were analyzed by LC/MS/MS. The results show that DHA targets paclitaxel to tumors: tumor AUCs are 61-fold higher for DHA-paclitaxel than for paclitaxel at equitoxic doses and eight-fold higher at equimolar doses. Likewise, at equi-toxic doses, the tumor AUCs of paclitaxel derived from i.v. DHA-paclitaxel are 6.1-fold higher than for paclitaxel derived from i.v. paclitaxel. The tumor concentration of paclitaxel derived from i.v. paclitaxel drops rapidly, so that by 16 h it has fallen to the same concentration (2.8 microM) as after an equi-toxic concentration of DHA-paclitaxel. In plasma, paclitaxel AUC after an MTD dose of DHA-paclitaxel is approximately 0.5% of DHA-paclitaxel AUC. Thus, the increase in tumor AUC and the limited plasma AUC of paclitaxel following DHA-paclitaxel administration are consistent with the increase in therapeutic index of DHA-paclitaxel relative to paclitaxel in the M109 mouse tumor model. A phase I clinical study has been completed at The Johns Hopkins Hospital to evaluate the safety of DHA-paclitaxel in patients with a variety of solid tumors. Twenty-one patients have been treated to date. The recommended phase II dose is 1100 mg/m(2), which is equivalent to 4.6 times the maximum approved paclitaxel dose on a molar basis. No alopecia or significant peripheral neuropathy, nausea, or vomiting have been observed. Asymptomatic, transient neutropenia has been the primary side effect. Eleven of 22 evaluable phase I patients transitioned from progressive to stable disease, as assessed by follow-up CT. Significant quality of life improvements have been observed. Thus, DHA-paclitaxel is well tolerated in patients and cures tumors in mice by targeting drug to tumors.

Phase I trial of pegylated liposomal doxorubicin and docetaxel in advanced breast cancer

PURPOSE

To develop a combination of pegylated liposomal doxorubicin (Doxil; Alza Pharmaceuticals, Palo Alto, CA) and docetaxel (Taxotere; Aventis Pharmaceutical, Parsipanny, NJ) that can be safely used for the treatment of advanced breast cancer.

PATIENTS AND METHODS

Forty-one patients with locally advanced (n = 10) or metastatic (n = 31) breast cancer received Doxil (30-, 40-, or 45-mg/m(2) intravenous [IV] infusion over 30 to 60 minutes), followed 1 hour later by docetaxel (60 or 75 mg/m(2) by IV infusion over 1 hour) in cohorts of three to six patients. Dose-limiting toxicity (DLT) was defined as febrile neutropenia, prolonged neutropenia, or grade 3 to 4 nonhematologic toxicity that occurred during cycle 1.

RESULTS

In conjunction with docetaxel 75 mg/m(2) every 4 weeks, the MTD of Doxil was 30 mg/m(2) and required granulocyte colony-stimulating factor (G-CSF) to prevent febrile neutropenia. Without G-CSF, the MTD was docetaxel 60 mg/m(2) and Doxil 30 mg/m(2) every 3 weeks; only 1 (7%) out of 15 patients treated at this dose level had cycle 1 DLT. Infusion reactions were common with Doxil with the recommended infusion schedule during the first cycle (55%) but were reduced with a modified schedule (7%). There was no clinically significant cardiac toxicity. Objective response occurred in eight of nine assessable patients with stage III disease and in 16 (52%) of 31 patients (95% confidence interval, 34% to 70%) with stage IV disease.

CONCLUSION

The recommended dose and schedule of this combination for further evaluation is Doxil 30 mg/m(2) and docetaxel 60 mg/m(2) given every 3 weeks without G-CSF. When used with G-CSF, it is Doxil 30 mg/m(2) and docetaxel 75 mg/m(2) every 4 weeks.

Digital Libraries and Recent Medical Informatics Research. Findings from the IMIA Yearbook of Medical Informatics 2001

The Yearbook of Medical Informatics is published annually by the International Medical Informatics Association (IMIA) and contains a selection of recent excellent papers on medical informatics research (http://www.med.uni-heidelberg.de/mi/yearbook/index.htm). The special topic of the just published Yearbook 2001 is "Digital Libraries and Medicine". Digital libraries have changed dramatically and will continue to change the way we work with medical knowledge. The selected papers present recent research and new results on digital libraries. As usual, the Yearbook 2001 also contains a variety of papers on other subjects relevant to medical informatics, such as Electronic Patient Records, Health Information Systems, Health and Clinical Management, Decision Support Systems, Education, as well as Image and Signal Processing. This paper will briefly introduce the contributions covering digital libraries and will show how medical informatics research contributes to this important topic.

Integration of clinical practice guidelines into a distributed regional electronic patient record for tumour-patients using XML: a means for standardization of the treatment processes

With the rising efforts to guarantee a high quality treatment in medicine and to reduce the costs in the health care system, Clinical Practice Guidelines (CPG) have developed into a very important reference in medicine. CPGs are especially useful for the standardization of multi-professional treatment processes like the care for patients with malignant diseases. The Tumour-Centre Heidelberg/Mannheim (Germany) leads a project to build up a regional, virtual distributed Electronic Patient Record (EPR) for patients with malignant diseases in the Rhein-Neckar-Area. Aims of the first stages of the project are the introduction of the distributed EPR to two co-operating pilot-clinics. In this context we intend to provide access for medical professionals not only to the data of the jointly treated patients, but also to relevant existing CPGs and other medical knowledge sources like Medline and Cochrane-Library. Knowledge and Patient data should be interlinked to offer patient-specific views on the CPG-information. As all professions have different information needs, this views should be presented individualized according to the demands of the users. We analysed three relevant CPGs and defined a meta-structure that will be refined to a common meta-structure for CPGs in Oncology. CPGs as well as structured patient-documents will be implemented in the Extensible Markup Language (XML), as this platform-independent technology seems to suit our needs for data exchange and presentation purposes best. The implementation process will be accompanied tightly with evaluations to gain experience for further expansions of the EPR. The vision of the project is, that by integrating CPGs in a shared distributed EPR, the way towards standardized treatment processes in a local, but multi-professional setting, and the efforts to guarantee a high quality treatment in Oncology can sufficiently be supported.

Systemic therapy

Our knowledge base on systemic therapy for breast cancer continues to expand, including further information regarding hormonal prevention in high-risk women, beneficial effects of tamoxifen in noninvasive disease, an update on primary systemic therapy, and optimization of adjuvant strategies, including data on adjuvant chemoendocrine regimens. The proper evaluation of high-dose strategies has been jeopardized by a serious episode of scientific misconduct. New data are also available on palliative options, bisphosphonates, antibody therapies, and novel targets. Data continue to evolve on the role and optimal schedules of taxanes in early-stage and advanced breast cancer. These and other important recent findings are discussed in this review article.

Early operable breast cancer

Early operable breast cancer is a potentially curable disease. However, a substantial number of patients are at risk for systemic recurrence and death. Breast conservation therapy (BCT) should be considered the preferred surgical option for most women with early operable breast cancer. Adjuvant systemic chemotherapy or hormonal therapy can substantially reduce, although not eliminate, the risk of recurrence and death. Neoadjuvant or primary systemic therapy (PST) in operable breast cancer slightly increases the number of women treated with breast conservation versus mastectomy. Although PST may identify women who are likely to have a better prognosis (those with a pathologic complete response), current PST strategies do not offer a survival advantage over standard adjuvant approaches. Early results of high-dose chemotherapy trials thus far have not shown any advantage over conventional dose therapy in high-risk patients with 10 or more positive lymph nodes. The role of adjuvant radiation therapy after mastectomy for all patients with high-risk early operable breast cancer is not fully defined.

Primary systemic therapy in operable breast cancer

PURPOSE

Laboratory studies suggest that primary systemic therapy (PST) could improve control of micrometastatic disease and impact on overall survival (OS). This article examines the rationale for and preclinical and clinical data of PST in operable breast cancer and the potential role of intermediate biomarkers as predictive and/or prognostic factors for response and survival.

DESIGN AND METHOD

We conducted an extensive literative review (including MEDLINE) on preclinical studies, single-arm feasibility studies, large randomized single- and multi-institutional trials, and laboratory correlate studies of PST in breast cancer.

RESULTS

Small trials in locally advanced disease showed high initial rates of response and local control. Six randomized clinical trials (RCTs) of PST for palpable, operable breast cancer have been reported since 1991 (from 204 to 1,523 patients each). These data clearly show a small but significant (less than 10%) absolute increase in the use of breast-conservation treatment (BCT) with similar rates of local control. Although one study showed better disease-free survival (DFS) and another showed better OS, most studies did not show any survival advantage of primary versus adjuvant systemic therapy. Thus far, pathologic complete response seems to be the best predictor of survival, but clinical response assessment correlates poorly with pathologic response. Pilot studies demonstrated feasibility of procuring tissue at diagnosis and after treatment for assays of potential intermediate biomarkers. Initial data suggest a potential correlation between markers of proliferation and apoptosis and in vivo chemotherapy sensitivity.

CONCLUSION

Thus far, RCTs of PST versus standard adjuvant therapy have not shown any clear benefit for DFS or OS in early breast cancer. Ongoing trials should determine if specific subsets of patients at risk would benefit from additional systemic therapy and the potential role of intermediate biomarkers in identifying such women. Although PST results in a small increase in the rate of BCT with similar rates of local control, current PST strategies should not replace standard adjuvant approaches. Rather, they represent an acceptable alternative to women with palpable, operable tumors and an excellent arena for clinical trials.

Phase II trial of doxorubicin and paclitaxel plus granulocyte colony-stimulating factor in metastatic breast cancer: an Eastern Cooperative Oncology Group Study

PURPOSE

Several groups have reported that the combination of doxorubicin plus paclitaxel given as a 3-hour intravenous (IV) infusion for up to eight cycles produces a high response rate (> 80%) and complete response rate (> 20%) in metastatic breast cancer, but is also complicated by a 20% incidence of congestive heart failure (CHF). The purpose of this phase II trial was to evaluate the antineoplastic activity of the regimen in a multi-institutional setting and to reduce the incidence of cardiotoxicity by limiting treatment to a maximum of six cycles.

PATIENTS AND METHODS

Fifty-two patients with advanced breast cancer received doxorubicin (60 mg/m(2) by IV injection) followed 15 minutes later by paclitaxel (200 mg/m(2) by IV infusion over 3 hours) every 3 weeks for four to six cycles.

RESULTS

Objective responses occurred in 25 of 48 assessable patients (52%; 95% confidence interval [CI], 38% to 66%), including four complete responses (8%; 95% CI, 0% to 16%). The median cumulative doxorubicin dose given was 240 mg/m(2) (range, 132 to 360 mg/m(2)). Eleven patients (21%) were documented as having a decrease in the LVEF below normal, including three patients (6%; 95% CI, 0% to 12%) who developed CHF.

CONCLUSION

The doxorubicin/paclitaxel regimen that we used is unlikely to produce an objective response rate of more than 70% and a complete response rate of more than 20% in patients with metastatic breast cancer, and proved to be excessively cardiotoxic for use in the adjuvant setting.

Systemic therapy

New data continue to refine our knowledge of systemic therapy for breast cancer. These include the third Oxford Overview on adjuvant systemic therapy, a small advantage of anthracycline regimens over CMF (cyclophosphamide, methotrexate, and 5-fluorouracil), and renewed interest in the "classic CMF" regimen. Primary chemotherapy offers a greater chance of breast conservation (although no survival advantage), and tamoxifen also benefits women with noninvasive disease. New data are available on biphosphonates, ovarian ablation, anti-estrogens, anti-HER-2 (human epidermal growth factor receptor-2) antibody, and HER-2 expression as a predictive or prognostic factor. Early results of high-dose chemotherapy have been released, and the role of taxanes in early and advanced disease continues to expand. This article reviews these and other recent advances.

New data on adjuvant therapy for breast cancer

In the past year, the results of the third Oxford Overview and recommendations from the St. Gallen International Consensus Panel on adjuvant treatment for breast cancer were published. Reports of trials addressing the role of anthracyclines and taxanes, as well as the optimal dosing schedule for cyclophosphamide, methotrexate, and 5-fluorouracil, also appeared. Data show that primary therapy increases the rate of breast conservation but not survival rates. The initial results of trials of high-dose chemotherapy with autologous hematopoietic support have been mixed. The usefulness of sentinel node biopsy in minimizing surgical morbidity and of biologic markers in predicting response to adjuvant therapy are areas of active research.

Adjuvant systemic management of early stage carcinoma of the breast

In the last three decades, there has been a gradual, though significant change in the treatment of early stage breast cancer. For almost a century, physicians advocated an "anatomical view" of the dissemination of this disease, which justified a more radical and mutilating treatment strategy. Finally in the mid-1970s, results from large randomized trials began to show that either mastectomy or lumpectomy with radiation therapy were appropriate treatment for women with early stage disease. These results suggested that breast cancer can actually be a systemic disease ("biological view") even in early stages. This hypothesis was confirmed when large randomized clinical trials demonstrated the effectiveness of adjuvant systemic therapy in controlling micrometastatic disease in women with node-positive and node negative disease. As we approach the end of this century, most patients with early stage disease will be offered some form of adjuvant systemic therapy, before or after local treatment with surgery, with or without local radiation therapy. There has been a lot of interest on the proper sequence of the therapeutic modalities, in particular with the recent publication of larger randomized trials of primary systemic therapy. This specific topic is discussed elsewhere in this issue by Singletary.

Stress, social support, and sense of coherence

In the Salutogenic Model, Aaron Antonovsky suggested that a sense of coherence (SOC) is the key determinant in the maintenance of health. He theorized that individuals with a strong SOC have the ability to (a) define life events as less stressful (comprehensibility), (b) mobilize resources to deal with encountered stressors (manageability), and (c) possess the motivation, desire, and commitment to cope (meaningfulness). To determine the effects of SOC on health outcomes, a greater understanding of the development and maintenance of SOC is necessary. Data from the 1994 Canadian National Population Health Survey were analyzed to investigate the effects of stress, social support, and recent traumatic life events on SOC. As predicted, stress and recent traumatic events were found to be inversely related to SOC, and social support was positively related. Traumatic events encountered in childhood were stronger predictors of SOC than traumatic life events experienced in adulthood.

Phase II study of ifosfamide, carboplatin, and oral etoposide chemotherapy for extensive-disease small-cell lung cancer: an Eastern Cooperative Oncology Group pilot study

PURPOSE

A phase II study of ifosfamide, carboplatin, and prolonged oral administration of etoposide (ICE) in patients with untreated extensive-disease (ED) small-cell lung cancer (SCLC) was conducted to assess toxicities, response, and median survival.

PATIENTS AND METHODS

Between July 1990 and August 1992, 35 patients were treated. ICE doses were ifosfamide 5 g/m2 by 24-hour continuous intravenous (CIV) infusion with mesna on day 1, carboplatin 300 mg/m2 intravenously (IV) on day 1, and etoposide 50 mg/m2 orally on days 1 to 21 every 4 weeks for up to six to eight cycles (schedule I). Because of severe hematologic toxicity in the first 18 patients, the last 17 patients received ifosfamide 3.75 mg/m2 IV on day 1, carboplatin 300 mg/m2 IV on day 1, and etoposide 50 mg orally on days 1 to 14 (schedule II).

RESULTS

Nine of 18 patients (50%) on schedule I had 13 episodes of severe hematologic toxicity (one death), and only two (11%) received full doses on cycle 2. However, with schedule II, only four of 17 patients (24%) developed severe hematologic toxicity, and eight (47%) received full doses on cycle 2. Objective responses were observed in 29 of 35 patients (83%) (schedule 1, 16 of 18 patients [89%]; schedule II, 13 of 17 patients [76%]). There were eight (23%) complete responses (CRs) and 21 (60%) partial responses (PRs). The median survival duration was 8.3 months, and 1- and 2-year survival rates were 37% and 14%, respectively.

CONCLUSION

ICE with oral etoposide has comparable activity with other regimens in ED SCLC. However, the 2-year survival rate may be higher and ICE with the lower doses of schedule II could be given safely with acceptable toxicity. Further studies of ICE compared with standard two-drug regimens are warranted.

The p53-dependent G1 cell cycle checkpoint pathway and ataxia-telangiectasia

The p53 protein is a critical participant in a signal transduction pathway which mediates a G1 cell cycle arrest and apoptotic cell death in mammalian cells after ionizing irradiation. Cells from patients with the cancer-prone, radiation-sensitive disorder, ataxia-telangiectasia (AT), exhibit suboptimal (delayed and/or defective) induction of p53 protein after ionizing radiation with some dependence on dose. Other protein products which participate in this signal transduction pathway, including p21WAF1/CIP1, Gadd45, and Mdm2, are also suboptimally induced in AT cells after ionizing radiation. Induction of p53 is also abnormal in AT cells following treatment with methylmethanesulfonate and bleomycin but appears relatively normal following treatment with UV-C irradiation or the topoisomerase inhibitors, etoposide and camptothecin. These results demonstrate a specific defect in this p53-dependent signal transduction pathway in AT cells. Potential models for this observed specificity of the AT defect as measured by p53 induction include problems with responses to: (a) single-strand, but not double-strand, DNA breaks; or (b) chemically, but not enzymatically, generated DNA ends.