Lasofoxifene versus fulvestrant for ER+/HER2- metastatic breast cancer with an ESR1 mutation: results from the randomized, phase II ELAINE 1 trial.

BACKGROUND: Acquired estrogen receptor alpha (ER/ESR1) mutations commonly cause endocrine resistance in ER+ metastatic breast cancer (mBC). Lasofoxifene, a novel selective ER modulator, stabilizes an antagonist conformation of wild-type and ESR1-mutated ER-ligand binding domains, and has antitumor activity in ESR1-mutated xenografts. PATIENTS AND METHODS: In this open-label, randomized, phase II, multicenter, ELAINE 1 study (NCT03781063), we randomized women with ESR1-mutated, ER+/human epidermal growth factor receptor 2 negative (HER2-) mBC that had progressed on an aromatase inhibitor (AI) plus a cyclin-dependent kinase 4/6 inhibitor (CDK4/6i) to oral lasofoxifene 5 mg daily or IM fulvestrant 500 mg (days 1, 15, and 29, and then every 4 weeks) until disease progression/toxicity. The primary endpoint was progression-free survival (PFS); secondary endpoints were safety/tolerability. RESULTS: A total of 103 patients received lasofoxifene (n = 52) or fulvestrant (n = 51). The most current efficacy analysis showed that lasofoxifene did not significantly prolong median PFS compared with fulvestrant: 24.2 weeks (∼5.6 months) versus 16.2 weeks (∼3.7 months; P = 0.138); hazard ratio 0.699 (95% confidence interval 0.434-1.125). However, PFS and other clinical endpoints numerically favored lasofoxifene: clinical benefit rate (36.5% versus 21.6%; P = 0.117), objective response rate [13.2% (including a complete response in one lasofoxifene-treated patient) versus 2.9%; P = 0.124], and 6-month (53.4% versus 37.9%) and 12-month (30.7% versus 14.1%) PFS rates. Most common treatment-emergent adverse events with lasofoxifene were nausea, fatigue, arthralgia, and hot flushes. One death occurred in the fulvestrant arm. Circulating tumor DNA ESR1 mutant allele fraction (MAF) decreased from baseline to week 8 in 82.9% of evaluable lasofoxifene-treated versus 61.5% of fulvestrant-treated patients. CONCLUSIONS: Lasofoxifene demonstrated encouraging antitumor activity versus fulvestrant and was well tolerated in patients with ESR1-mutated, endocrine-resistant mBC following progression on AI plus CDK4/6i. Consistent with target engagement, lasofoxifene reduced ESR1 MAF, and to a greater extent than fulvestrant. Lasofoxifene may be a promising targeted treatment for patients with ESR1-mutated mBC and warrants further investigation.

How iMALDI can improve clinical diagnostics.

Protein mass spectrometry (MS) is an indispensable tool to detect molecular signatures that can be associated with cellular dysregulation and disease. Despite its huge success in the life sciences, where it has led to novel insights into disease mechanisms and the identification of potential protein biomarkers, protein MS is rarely used for clinical protein assays. While conventional matrix-assisted laser desorption/ionization (MALDI) MS is not compatible with complex samples, liquid chromatography-MS (LC-MS)-based assays may be too complex and may lack the robustness and ease of automation required for routine use in the clinic. Therefore, clinical protein assays are dominated by immunohistochemistry and immunoassays which, however, often lack standardization and fully depend on antibody specificity. Immuno-MALDI (iMALDI) MS may overcome these hurdles by utilizing anti-peptide antibodies for the specific enrichment of targeted analytes and on-target detection of the captured analytes, thus combining the unique properties of MS for the unambiguous detection and quantitation of analytes with a workflow that can be fully automated. Here we discuss the requirements for clinical protein assays, the pitfalls of existing methods, how iMALDI has been successfully used to quantify endogenous peptides and proteins from clinical samples, as well as its potential as a powerful tool for companion diagnostics in the light of precision medicine.

Lung cancer care trajectory at a Canadian centre: an evaluation of how wait times affect clinical outcomes.

BACKGROUND: Lung cancer continues to be one of the most common cancers in Canada, with approximately 28,400 new cases diagnosed each year. Although timely care can contribute substantially to quality of life for patients, it remains unclear whether it also improves patient outcomes. In this work, we used a set of quality indicators that aim to describe the quality of care in lung cancer patients. We assessed adherence with existing guidelines for timeliness of lung cancer care and concordance with existing standards of treatment, and we examined the association between timeliness of care and lung cancer survival. METHODS: Patients with lung cancer diagnosed between 2010 and 2015 were identified from the Pulmonary Division Lung Cancer Registry at our centre. RESULTS: We demonstrated that the interdisciplinary pulmonary oncology service successfully treated most of its patients within the recommended wait times. However, there is still work to be done to decrease variation in wait time. Our results demonstrate a significant association between wait time and survival, supporting the need for clinicians to optimize the patient care trajectory. INTERPRETATION: It would be helpful for Canadian clinicians treating patients with lung cancer to have wait time guidelines for all treatment modalities, together with standard definitions for all time intervals. Any reductions in wait times should be balanced against the need for thorough investigation before initiating treatment. We believe that our unique model of care leads to an acceleration of diagnostic steps. Avoiding any delay associated with referral to a medical oncologist for treatment could be an acceptable strategy with respect to reducing wait time.

Identification of performance indicators across a network of clinical cancer programs.

BACKGROUND: Cancer quality indicators have previously been described for a single tumour site or a single treatment modality, or according to distinct data sources. Our objective was to identify cancer quality indicators across all treatment modalities specific to breast, prostate, colorectal, and lung cancer. METHODS: Candidate indicators for each tumour site were extracted from the relevant literature and rated in a modified Delphi approach by multidisciplinary groups of expert clinicians from 3 clinical cancer programs. All rating rounds were conducted by e-mail, except for one that was conducted as a face-to-face expert panel meeting, thus modifying the original Delphi technique. Four high-level indicators were chosen for immediate data collection. A list of confounding variables was also constructed in a separate literature review. RESULTS: A total of 156 candidate indicators were identified for breast cancer, 68 for colorectal cancer, 40 for lung cancer, and 43 for prostate cancer. Iterative rounds of ratings led to a final list of 20 evidence- and consensus-based indicators each for colorectal and lung cancer, and 19 each for breast and prostate cancer. Approximately 30 clinicians participated in the selection of the breast, lung, and prostate indicators; approximately 50 clinicians participated in the selection of the colorectal indicators. CONCLUSIONS: The modified Delphi approach that incorporates an in-person meeting of expert clinicians is an effective and efficient method for performance indicator selection and offers the added benefit of optimal clinician engagement. The finalized indicator lists for each tumour site, together with salient confounding variables, can be directly adopted (or adapted) for deployment within a performance improvement program.

Retrospective analysis of the effect of CAPOX and mFOLFOX6 dose intensity on survival in colorectal patients in the adjuvant setting.

BACKGROUND: Despite lack of a true comparative study, the folfox (5-fluorouracil-leucovorin-oxaliplatin) and capox (capecitabine-oxaliplatin) regimens are believed to be similar in their efficacy and tolerability in the treatment of stage iii colorectal cancer. However, that belief has been disputed, because real-life data suggest that the capox regimen is more toxic, leading to more frequent reductions in the delivered dose intensity-thus raising questions about the effect of dose intensity on clinical outcomes. METHODS: A retrospective data review for two Canadian institutions, the Segal Cancer Centre and the Tom Baker Cancer Centre, considered patients diagnosed with stage iii colorectal cancer during 2006-2013. Primary endpoints were dose intensity and toxicity, with a secondary endpoint of disease-free survival. RESULTS: The study enrolled 180 eligible patients (80 at the Segal Cancer Centre, 100 at the Tom Baker Cancer Centre). Of those 180 patients, 75 received capox, and 105 received mfolfox6. In the capox group, a significant dose reduction was identified for capecitabine compared with 5-fluorouracil in mfolfox6 group (p = 0.0014). Similarly, a significant dose reduction was observed for oxaliplatin in mfolfox6 compared with oxaliplatin in capox (p = 0.0001). Compared with the patients receiving capox, those receiving mfolfox6 were twice as likely to experience a treatment delay of more than 1 cycle-length (p = 0.03855). Toxicity was more frequent in patients receiving mfolfox6 (nausea: 30% vs. 18%; diarrhea: 47% vs. 24%; peripheral sensory neuropathy: 32% vs. 3%). At a median follow-up of 40 months, preliminary data showed no difference in disease-free survival (p = 0.598). Pooled data from both institutions were also separately analyzed, and no significant differences were found. CONCLUSIONS: Our results support the use of capox despite a lack of head-to-head randomized trial data.

Challenges in initiating and conducting personalized cancer therapy trials: perspectives from WINTHER, a Worldwide Innovative Network (WIN) Consortium trial.

Advances in 'omics' technology and targeted therapeutic molecules are together driving the incorporation of molecular-based diagnostics into the care of patients with cancer. There is an urgent need to assess the efficacy of therapy determined by molecular matching of patients with particular targeted therapies. WINTHER is a clinical trial that uses cutting edge genomic and transcriptomic assays to guide treatment decisions. Through the lens of this ambitious multinational trial (five countries, six sites) coordinated by the Worldwide Innovative Networking Consortium for personalized cancer therapy, we discovered key challenges in initiation and conduct of a prospective, omically driven study. To date, the time from study concept to activation has varied between 19 months at Gustave Roussy Cancer Campus in France to 30 months at the Segal Cancer Center, McGill University (Canada). It took 3+ years to be able to activate US sites due to national regulatory hurdles. Access to medications proposed by the molecular analysis remains a major challenge, since their availability through active clinical trials is highly variable over time within sites and across the network. Rules regarding the off-label use of drugs, or drugs not yet approved at all in some countries, pose a further challenge, and many biopharmaceutical companies lack a simple internal mechanism to supply the drugs even if they wish to do so. These various obstacles should be addressed to test and then implement precision medicine in cancer.

A real-life experience using panitumumab in chemo-refractory metastatic colorectal cancer patients: a retrospective analysis at the Jewish General Hospital, 2009-2012.

BACKGROUND: Panitumumab is a fully human monoclonal antibody, directed against the epidermal growth factor receptor, that was shown to be effective in third-line metastatic colorectal cancer. We performed a retrospective analysis of patients with chemo-refractory non-KRAS-mutated metastatic colorectal cancer, who received panitumumab at the Jewish General Hospital in Montreal, Canada, between 2009 and 2012. METHODS: This chart review included 44 patients (median age: 60 years; performance status: 0-3), of whom 50% had already received three lines of treatment. The primary endpoint was progression-free survival (pfs). Secondary endpoints were overall survival and safety. Tumour progression was determined by radiologic assessments performed once every 3 months per clinical guidelines or by clinical deterioration as determined by the clinician-investigator. RESULTS: In our sample, median pfs was 21.86 ± 5.23 weeks (95% confidence interval: 12.9 to 36.9 weeks) and overall survival was 35.14 ± 7.75 weeks (95% confidence interval: 25.6 to 73.4 weeks) with a median of 5 cycles of panitumumab treatment. The most frequently reported toxicities with panitumumab were skin toxicity (16.2% grade 3) and hypomagnesemia (10.8% grade 3). No infusion reactions were reported. CONCLUSIONS: Despite a small sample size from a single institution, our survival and efficacy data are encouraging and comparable to results obtained from the registration panitumumab trial. Our findings suggest that panitumumab can be effective and tolerable in a real-world setting.

Bevacizumab-based therapy for colorectal cancer: experience from a large Canadian cohort at the Jewish General Hospital between 2004 and 2009.

BACKGROUND: Before its regulatory approval in Canada, bevacizumab to treat patients with colorectal cancer (crc) was accessed through the Bevacizumab Expanded Access Trial and a special-access program at the Jewish General Hospital. We retrospectively evaluated patient outcomes in that large cohort. METHODS: All patients (n = 196) had metastatic crc, were bevacizumab-naïve, and received bevacizumab in combination with chemotherapy at the Jewish General Hospital between 2004 and 2009. We collected patient demographics and clinical characteristics; relevant medical history, disease stage and tumour pathology at diagnosis; type, duration, and line of therapy; grades 3 and 4 adverse events (aes), time to disease progression (ttp), and overall survival (os) from diagnosis. RESULTS: Median follow-up was 36.0 months. Median ttp was 8.0 months [95% confidence interval (ci): 7.0 to 9.0 months). Median os was 41.0 months (95% ci: 36.0 to 47.0 months). Of the 40 grades 3 and 4 bevacizumab-related aes experienced by 38 patients (19.4%), the most common were thrombocytopenia (n = 17), deep-vein thrombosis (n = 6), pulmonary embolism (n = 4), and hypertension (n = 3). CONCLUSIONS: In an expanded access setting, our data reflect the efficacy and safety of bevacizumab-based therapy in the controlled post-registration clinical trial setting.

Benefits, issues, and recommendations for personalized medicine in oncology in Canada.

The burden of cancer for Canadian citizens and society is large. New technologies have the potential to increase the use of genetic information in clinical decision-making, furthering prevention, surveillance, and safer, more effective drug therapies for cancer patients. Personalized medicine can have different meanings to different people. The context for personalized medicine in the present paper is genetic testing, which offers the promise of refining treatment decisions for those diagnosed with chronic and life-threatening illnesses. Personalized medicine and genetic characterization of tumours can also give direction to the development of novel drugs. Genetic testing will increasingly become an essential part of clinical decision-making. In Canada, provinces are responsible for health care, and most have unique policies and programs in place to address cancer control. The result is inconsistency in access to and delivery of therapies and other interventions, beyond the differences expected because of demographic factors and clinical education. Inconsistencies arising from differences in resources, policy, and application of evidence-informed personalized cancer medicine exacerbate patient access to appropriate testing and quality care. Geographic variations in cancer incidence and mortality rates in Canada-with the Atlantic provinces and Quebec having higher rates, and British Columbia having the lowest rates-are well documented. Our purpose here is to provide an understanding of current and future applications of personalized medicine in oncology, to highlight the benefits of personalized medicine for patients, and to describe issues and opportunities for improvement in the coordination of personalized medicine in Canada. Efficient and more rapid adoption of personalized medicine in oncology in Canada could help overcome those issues and improve cancer prevention and care. That task might benefit from the creation of a National Genetics Advisory Panel that would review research and provide recommendations on tests for funding or reimbursement, guidelines, service delivery models, laboratory quality assurance, education, and communication. More has to be known about the current state of personalized cancer medicine in Canada, and strategies have to be developed to inform and improve understanding and appropriate coordination and delivery. Our hope is that the perspectives emphasized in this paper will stimulate discussion and further research to create a more informed response.

Quality of life during the course of cancer treatment in older newly diagnosed patients. Results of a prospective pilot study.

BACKGROUND: The aim of this prospective study was to report the quality of life (QoL) of older cancer patients during the first year after diagnosis and factors influencing QoL. PATIENTS AND METHODS: Newly diagnosed patients aged ≥65 years were recruited for a pilot prospective cohort study at the Jewish General Hospital, Montreal, Canada. Participants were interviewed at baseline, and at 1.5, 3, 4.5, 6, and 12 months. QoL was assessed at each interview using the European Organization for the Research and Treatment of Cancer Quality of Life Core Questionnaire with 30 items. Logistic regression was conducted to determine which sociodemographic, health, and functional status characteristics were associated with decline in global health status/QoL between baseline and 12-month follow-up. RESULTS: There were 112 participants at baseline (response rate 72%), median age of 74.1, and 70% were women. Between baseline and 12-month follow-up (n=78), 18 participants (23.1%) declined ≥10 points in global health status/QoL, while 34 participants (43.6%) remained stable and 23 participants (33.3%) improved ≥10 points. None of the sociodemographic, health, and functional status variables were associated with decline in logistic regression analyses. CONCLUSION: Almost 25% of older adults experienced clinically relevant decline in their QoL. Further research is needed on which factors influence decline in QoL in older adults.

Anthracycline cardiotoxicity in the elderly cancer patient: a SIOG expert position paper.

BACKGROUND: Comorbidities and risk factors likely to complicate treatment are common in elderly cancer patients. Anthracyclines remain the cornerstone of first-line therapy for non-Hodgkin's lymphoma (NHL) and metastatic and early breast cancer but can cause congestive heart failure. Elderly patients are at increased risk of this event and measures to reduce it should be considered. METHODS: A committee of experts in breast cancer and NHL met under the auspices of the International Society for Geriatric Oncology to review the literature and make recommendations, based on level of evidence, for the assessment, treatment and monitoring of elderly patients requiring anthracyclines. RESULTS AND RECOMMENDATIONS: Use of anthracycline-based chemotherapy illustrates many of the dilemmas facing elderly cancer patients. Age in itself should not prevent access to potentially curative treatment or treatment that prolongs life or improves its quality. The risk of cardiotoxicity with conventional anthracyclines is increased by the following factors: an existing or history of heart failure or cardiac dysfunction; hypertension, diabetes and coronary artery disease; older age (independent of comorbidities and performance status); prior treatment with anthracyclines; higher cumulative dose of anthracyclines and short infusion duration. The fact that cumulative and irreversible cardiotoxicity is likely to be greater in this population than among younger patients calls for effective pretreatment screening for risk factors, rigorous monitoring of cardiac function and early intervention. Use of liposomal anthracycline formulations, prolonging the infusion time for conventional anthracyclines and cardioprotective measures should be considered. However, when treatment is being given with curative intent, care should be taken to ensure reduced cardiotoxicity is not achieved at the expense of efficacy.

A network approach to developing immuno-oncology combinations in Canada.

Immune checkpoint inhibitors have revolutionized care for many cancer indications, with considerable effort now being focused on increasing the rate, depth, and duration of patient response. One strategy is to combine immune strategies (for example, ctla-4 and PD-1/L1-directed agents) to harness additive or synergistic efficacy while minimizing toxicity. Despite encouraging results with such combinations in multiple tumour types, numerous clinical challenges remain, including a lack of biomarkers that reliably predict outcome, the emergence of therapeutic resistance, and optimal management of immune-related toxicities. Furthermore, the selection of ideal combinations from the myriad of immune, systemic, and locoregional therapies has yet to be determined. A longitudinal network-based approach could offer advantages in addressing those critical questions, including long-term follow-up of patients beyond individual trials. The molecular cancer registry Personalize My Treatment, managed by the Networks of Centres of Excellence nonprofit organization Exactis Innovation, is uniquely positioned to accelerate Canadian immuno-oncology (io) research efforts throughout its national network of cancer sites. To gain deeper insight into how a pan-Canadian network could advance research in io combinations, Exactis invited preeminent clinical and scientific advisors from across Canada to a roundtable event in November 2017. The present white paper captures the expert advice provided: leverage longitudinal patient data collection; facilitate network collaboration and assay harmonization; synergize with existing initiatives, networks, and biobanks; and develop an io combination trial based on Canadian discoveries.

The McGill University department of oncology: structure depicts the shape of evolving knowledge.

The McGill University Department of Oncology has changed and expanded since its inception in 1990, responding to the move to interdisciplinary clinical care, teaching, and research. Although the traditional Divisions have been maintained to correspond to University and Royal College interfaces, the department has steadily been generating a variety of cross-departmental and interdisciplinary programs in which new insights into clinical care and biology are being generated. In research areas ranging from psychosocial and fundamental to translational and clinical therapeutics, interdisciplinarity and an emphasis on clinician-scientists are critical features.

Developing a model of a patient-group pathway to accessing cancer clinical trials in Canada.

Background: Colorectal Cancer Canada, in partnership with a Scientific Advisory Committee, is developing a Canadian Patient Group Pathway to Accessing Cancer Clinical Trials ("Pathway"). A central element of the Pathway is presented here-namely, a set of recommendations and tools aimed at each stakeholder group. Methods: A summary of the peer-reviewed and grey literature informed discussions at a meeting, held in June 2017, in which a cross-section of stakeholders reached consensus on the potential roles of patient groups in the cancer clinical trials process, barriers to accessing cancer clinical trials, best practice models for patient-group integration, and a process for developing the Pathway. Canadian recommendations and tools were subsequently developed by a small working group and reviewed by the Scientific Advisory Committee. Results: The major output of the consensus conference was agreement that the Clinical Trials Transformation Initiative (ctti) model, successfully applied in the United States, could be adapted to create a Canadian Pathway. Two main differences between the Canadian and American cancer clinical research environments were highlighted: the effects of global decision-making and systems of regulatory and funding approvals. The working group modified the ctti model to incorporate those aspects and to reflect Canadian stakeholder organizations and how they currently interact with patient groups. Conclusions: Developing and implementing a Canadian Pathway that incorporates the concepts of multi-stakeholder collaboration and the inclusion of patient groups as equal partners is expected to generate significant benefits for all stakeholders. The next steps to bring forward a proposed Pathway will involve engaging the broader cancer research community. Clinical trial sponsors will be encouraged to adopt a Charter recognizing the importance of including patient groups, and to support the training of patient groups through an independent body to ensure quality research partners. Integration of patient groups into the process of developing "real world" evidence will be advanced by a further consensus meeting being organized by Colorectal Cancer Canada for 6-7 November 2018.

In vivo and in vitro mechanisms of drug resistance in a rat mammary carcinoma model.

Many in vitro tumor models have been examined to help understand the precise mechanisms responsible for drug resistance. The importance of these results in vivo remains uncertain. MatB 13762 is a rat mammary adenocarcinoma cell line that can be grown both in vitro and as a solid tumor in Fischer 344 rats, thus permitting the examination of tumor cell drug resistance under both conditions. Two cell lines have been selected in vitro for resistance to Adriamycin (AdrR) and melphalan (MlnR), respectively. Each subline has the following features: AdrR, increased mdr-1 messenger RNA, a high level of cross-resistance to vincristine and atypical low level resistance to melphalan and 1,3-bis(2-chloroethyl)-1-nitrosourea, decreased cellular glutathione content, and increased expression of Yc and Yp glutathione S-transferase isozymes; MlnR, low level drug resistance to melphalan and cross-resistance to 1,3-bis(2-chloroethyl)-1-nitrosourea, Adriamycin, and vincristine; increased cellular concentration of glutathione; elevated glutathione S-transferase activity; and greatly increased messenger RNA specific to the Yc and Yp glutathione-S-transferase subunits. Most of the biochemical and molecular features described above are present but significantly less prominent in tumors grown in vivo. This model provides the opportunity to examine the magnitude of expression and the clinical significance of in vitro resistance in an in vivo model.

Eradication of hepatic metastases of carcinoma H-59 by combination chemoimmunotherapy with liposomal muramyl tripeptide, 5-fluorouracil, and leucovorin.

We have investigated the effect of a combined chemoimmunotherapy protocol with liposomal muramyl tripeptide phosphatidylethanolamine (MTP-PE), 5-fluorouracil (5-FU), and 5-formyltetrahydrofolate (leucovorin) on the growth of hepatic metastases using carcinoma H-59, a liver-homing subline of the Lewis lung carcinoma (P. Brodt, Cancer Res., 46: 2442-2448, 1986). C57BL/6 mice inoculated with the tumor cells via the intrasplenic route received three i.v. injections of liposomal MTP-PE, the first of which was administered 3 days prior to tumor cell inoculation. Chemotherapy with 5-FU and leucovorin at the maximal tolerated doses (30 mg/kg per injection) was initiated immediately after tumor inoculation and continued on alternate days for a total of 4 injections. The incidence of liver metastases in animals which received the combined therapy was compared to that in animals treated with chemotherapy or immunotherapy alone. We found that while the number of liver metastases was reduced in all of the treatment groups as compared to control untreated or placebo-treated animals, the combined effect of 5-FU leucovorin and liposomal MTP-PE was significantly better than that of chemotherapy or immunotherapy alone. This was reflected in a reduced incidence (70% as compared to 100% in all other groups) and in a significant reduction in the number and size of the liver nodules. Our results suggest that the efficacy of 5-FU and leucovorin in the treatment of hepatic metastases could be significantly augmented by the addition of the liposome-encapsulated immunoadjuvant MTP-PE.

Transforming growth factor beta 1 promotes spontaneous transformation of cultured rat liver epithelial cells.

The neoplastic transformation of cultured rat liver epithelial cells by various means has consistently been associated with the development of resistance to the mito-inhibitory effect of transforming growth factor beta (TGF-beta), suggesting that such phenotype plays a mechanistic role during the transformation of these cells. We have studied the induction of the "TGF-beta-resistant" phenotype in a clonal strain of early passage WB-F344 normal cultured rat liver epithelial cells, the proliferation of which was markedly inhibited by TGF-beta. The control WB cells in continuous culture slowly developed TGF-beta resistance. However, when the same cells were exposed to step-wise increases of TGF-beta concentration in their culture medium, the development of TGF-beta resistance was accelerated. Cells which had been grown in medium containing 1 ng/ml TGF-beta developed colony-forming capacity in soft agar containing epidermal growth factor. Cells which were grown in media containing 5 and 10 ng/ml TGF-beta demonstrated a low level of colony-forming efficiency in soft agar medium without added epidermal growth factor and tumorigenicity in isogeneic rats. These TGF-beta-resistant cells also exhibited progressively increasing levels of expression of the c-fos and and myc mRNA, and increased resistance to the cytotoxicity of Adriamycin and melphalan. The latter phenomenon was accompanied by an increase in the mdr-1 mRNA expression, cellular glutathione level, and glutathione S-transferase activity. The results suggest that chronic exposure to high concentration of TGF-beta promotes the spontaneous neoplastic transformation of cultured rat liver epithelial cells, and that this process may represent one of the mechanisms of cellular adaptation for induction of the multidrug-resistant phenotype during the carcinogenesis of epithelial cells.

Phenotypic expression in spontaneously transformed cultured rat liver epithelial cells.

Five clonal cell strains of an early-passage normal rat liver epithelial cell line were transformed spontaneously using the protocol of "selective culture" condition. Twelve cell lines were established from the tumors produced after injecting these transformed cells into 1-day-old syngeneic rats. The phenotypic expressions of these spontaneously transformed tumor cell lines were studied and compared to those of cell lines obtained from tumors produced by rat liver epithelial cells transformed by N-methyl-N'-nitro-N-nitrosoguanidine. Like the chemically induced tumor cells, spontaneously transformed tumor cells exhibited phenotypic heterogeneity in the expression of isoenzymes, proto-oncogenes, growth factors and their receptors, and cellular responses to the effect of growth factors. However, unlike the chemically induced tumor cells, these spontaneously induced tumor cells did not express the "resistant phenotypes" characteristic of chemically induced or promoted tumors. Although all the spontaneously induced tumor cell lines expressed variable amounts of transforming growth factor-alpha mRNA, it was not functionally coordinated with the expression of its receptor, the epidermal growth factor receptor. Thus, spontaneously transformed rat liver epithelial cells demonstrate both similarity and diversity in their phenotypic expression when compared to their chemically induced counterpart. This model of spontaneous transformation of cultured rat liver epithelial cells may be useful for the mechanistic study of non-chemically induced carcinogenesis.

Efficacy and toxicity of ifosfamide stereoisomers in an in vivo rat mammary carcinoma model.

Ifosfamide (IFF) is a nitrogen mustard with significant activity against a number of tumors. Since it is a chiral molecule, it has been suggested that enantioselective metabolism could result in different efficacy and toxicity profiles for (R)- and (S)-ifosfamide. Both experimental animal and clinical data suggest that N-dechloroethyl metabolites of (S)-IFF are more significantly associated with neurological toxicity, which may limit therapeutic use of IFF. We have used purified ifosfamide enantiomers to examine the pharmacokinetics; spectrum of toxicity including lethality, weight loss, and myelosuppression; and antitumor effects of the mixture compared to each of the purified enantiomers. In the MatB mammary carcinoma grown in female Fischer rats we demonstrated that the antitumor efficacy appears to be the same for (R)-IFF and (S)-IFF, while the (R)-IFF has greater myelotoxicity. Pharmacokinetic analysis of plasma concentration-time confirms that the (R)-IFF is metabolized to a greater extent than (S)-IFF via the activation pathway. These data suggest that purified (R)-IFF may be an effective way to delivery active cytotoxic drug while limiting the generation of neurotoxic metabolites.

Selenium-induced cytotoxicity of human leukemia cells: interaction with reduced glutathione.

Selenium exists in a number of forms with differing valence states, some of which have shown antitumor activity. We studied the tumoricidal activity of four currently available selenium forms against a human leukemia cell line and exploited the differences among them to investigate the mechanism of antitumor action. Only selenocystine and sodium selenite showed antitumor activity, and these were also the only compounds which demonstrated significant redox chemistry, including depletion of cellular glutathione, stimulation of glutathione reductase, and stimulation of oxygen consumption. The interaction of these two compounds with glutathione suggests an intriguing potential role for them in cancer therapy.