Malformation of incisor teeth in Grem2⁻/⁻ mice.

GREMLIN 2 (GREM2)--formerly, protein related to Dan and cerberus (PRDC)-is a potent antagonist of the bone morphogenetic proteins 2 and 4, but little else in known about its functions. We found that Grem2(-/-) mice developed small deformed mandibular and maxillary incisors, indicating that GREMLIN2 is required for normal tooth morphogenesis. Although DEXA scans suggested that bone mineral density might be increased in Grem2(-/-) mice, histology did not reveal any evident bone phenotype. Grem2(-/-) mice did not display any other notable phenotypes evaluated in a high-throughput screening process that encompassed a range of immunologic, metabolic, ophthalmic, and behavioral parameters. Our findings indicate that Grem2 can be added to the growing list of genes that affect tooth development in mice.

Nephronophthisis and retinal degeneration in tmem218-/- mice: a novel mouse model for Senior-Løken syndrome?

Mice deficient in TMEM218 (Tmem218(-/-) ) were generated as part of an effort to identify and validate pharmaceutically tractable targets for drug development through large-scale phenotypic screening of knockout mice. Routine diagnostics, expression analysis, histopathology, and electroretinogram analyses completed on Tmem218(-/-) mice identified a previously unknown role for TMEM218 in the development and function of the kidney and eye. The major observed phenotypes in Tmem218(-/-) mice were progressive cystic kidney disease and retinal degeneration. The renal lesions were characterized by diffuse renal cyst development with tubulointerstitial nephropathy and disruption of tubular basement membranes in essentially normal-sized kidneys. The retinal lesions were characterized by slow-onset loss of photoreceptors, which resulted in reduced electroretinogram responses. These renal and retinal lesions are most similar to those associated with nephronophthisis (NPHP) and retinitis pigmentosa in humans. At least 10% of NPHP cases present with extrarenal conditions, which most often include retinal degeneration. Senior-Løken syndrome is characterized by the concurrent development of autosomal recessive NPHP and retinitis pigmentosa. Since mutations in the known NPHP genes collectively account for only about 30% of NPHP cases, it is possible that TMEM218 could be involved in the development of similar ciliopathies in humans. In reviewing all other reported mouse models of NPHP, we suggest that Tmem218(-/-) mice could provide a useful model for elucidating the pathogenesis of cilia-associated disease in both the kidney and the retina, as well as in developing and testing novel therapeutic strategies for Senior-Løken syndrome.

Amelogenesis imperfecta and other biomineralization defects in Fam20a and Fam20c null mice.

The FAM20 family of secreted proteins consists of three members (FAM20A, FAM20B, and FAM20C) recently linked to developmental disorders suggesting roles for FAM20 proteins in modulating biomineralization processes. The authors report here findings in knockout mice having null mutations affecting each of the three FAM20 proteins. Both Fam20a and Fam20c null mice survived to adulthood and showed biomineralization defects. Fam20b (-/-) embryos showed severe stunting and increased mortality at E13.5, although early lethality precluded detailed investigations. Physiologic calcification or biomineralization of extracellular matrices is a normal process in the development and functioning of various tissues (eg, bones and teeth). The lesions that developed in teeth, bones, or blood vessels after functional deletion of either Fam20a or Fam20c support a significant role for their encoded proteins in modulating biomineralization processes. Severe amelogenesis imperfecta (AI) was present in both Fam20a and Fam20c null mice. In addition, Fam20a (-/-) mice developed disseminated calcifications of muscular arteries and intrapulmonary calcifications, similar to those of fetuin-A deficient mice, although they were normocalcemic and normophosphatemic, with normal dentin and bone. Fam20a gene expression was detected in ameloblasts, odontoblasts, and the parathyroid gland, with local and systemic effects suggesting both local and/or systemic effects for FAM20A. In contrast, Fam20c (-/-) mice lacked ectopic calcifications but were severely hypophosphatemic and developed notable lesions in both dentin and bone to accompany the AI. The bone and dentin lesions, plus the marked hypophosphatemia and elevated serum alkaline phosphatase and FGF23 levels, are indicative of autosomal recessive hypophosphatemic rickets/osteomalacia in Fam20c (-/-) mice.

Effect of alternating combination chemotherapy on survival of ambulatory patients with metastatic large-cell and adenocarcinoma of the lung. A Southwest Oncology Group Study.

Using a randomized prospective trial design, chemotherapy with 5-fluorouracil, vincristine, and mitomycin C (FOMi) was compared with cyclophosphamide, doxorubicin, and cisplatin (CAP) and with FOMi alternating with CAP (FOMi/CAP) in 452 eligible patients with metastatic large-cell undifferentiated and adenocarcinoma of the lung. Objective responses were obtained in 26%, 17%, and 22% of patients treated with FOMi, CAP, and FOMi/CAP, respectively. The median survival was similar for FOMi, CAP, and FOMi/CAP therapies (20, 24, and 23 weeks, respectively), but the overall survival (log rank test), 1-year survival, and remission duration were longer for FOMi/CAP-treated patients. Survival was significantly longer for fully ambulatory FOMi/CAP-treated patients compared with either FOMi (P = .01) or CAP (P = .04). Younger patients treated with full doses of therapy responded more often than older patients receiving reduced drug doses (26% and 11%, respectively; P = .003). A prognostic factor regression analysis of all eligible patients indicates that sex, performance status, stage, and treatment assigned were important independent variables determining survival (P less than .05). Toxicity was comparable in each treatment group.

Ifosfamide in the management of gynecologic cancers.

Ifosfamide, an alkylating agent chemically similar to cyclophosphamide, has been tested both as a single agent and in combination therapy for a variety of gynecologic cancers. In celomic epithelial carcinoma of the ovary, single agent ifosfamide yields response rates ranging from 19% to 79% and, most significantly, responses in patients who are refractory to cisplatin. Use in combination with both cisplatin and carboplatin has been reported, but the relative merits of these two combinations are indeterminate at present. In carcinoma of the cervix, response rates for ifosfamide alone range from 20% to 40% in patients who have not received prior chemotherapy. Very high response rates from 67% to 86% have been reported with ifosfamide in combination with platinum compounds with or without other agents such as doxorubicin and bleomycin. No studies have yet demonstrated superiority of combination therapy. Data from the Gynecologic Oncology Group demonstrate activity for ifosfamide alone in mixed mesodermal sarcomas of the uterus. Finally, anecdotal data note responses in endometrial carcinoma and germ cell carcinomas of the ovary. Thus, it appears that ifosfamide has significant activity in a variety of gynecologic cancers and deserves further testing as a part of combination chemotherapy in at least celomic epithelial carcinomas of the ovary, cervix carcinomas, and mixed mesodermal sarcomas of the uterus.

The role of ifosfamide in gynecologic cancer.

Ifosfamide exhibits promising activity in a variety of gynecologic neoplasms. In carcinoma of the ovary, the drug shows clear-cut activity, effecting responses in patients who have proven clinically resistant to cisplatin-based combination chemotherapy. In carcinoma of the cervix, the drug also appears to be highly active, both as a single agent and in combination with other agents, such as the platinum compounds. The drug is active in uterine sarcomas and appears to be the most active agent studied to date in mixed mesodermal sarcomas of the uterus. The drug's role in combination with other agents in the treatment of all of these neoplasms is under study, but cannot be determined from currently available data on combination therapy. Its activity in other gynecologic tumors, such as endometrial carcinoma and ovarian germ cell tumors, is also indeterminate at present. Although further studies are needed, current evidence supports the contention that ifosfamide is a major new active drug in the management of gynecologic cancers.

The platinum compounds and paclitaxel in the management of carcinomas of the endometrium and uterine cervix.

Endometrial carcinoma and squamous cell carcinoma of the cervix are common invasive neoplasms of the female genital tract. Early diagnosis of a majority of patients has resulted in high cure rates for both diseases. In the last two decades, a growing number of active systemic drugs have been identified. Cisplatin has been extensively studied in both neoplasms and has clear activity (20% response rate in endometrial carcinoma and 23% response rate in squamous cell carcinoma of the cervix). Recently, paclitaxel (Taxol; Bristol-Myers Squibb Company, Princeton, NJ) has been shown to be clearly active in both (35% response rate in endometrial carcinoma and 17% response rate in squamous cell carcinoma of the cervix). The apparent clinical non-cross-resistance between paclitaxel and cisplatin in other neoplasms like ovarian carcinoma makes combinations including these two agents of great interest. In endometrial carcinoma, a phase I trial of cisplatin plus doxorubicin plus escalating paclitaxel doses is being performed by the Gynecologic Oncology Group (GOG). Based on the outcome of this study, a future randomized trial will compare the current standard, doxorubicin plus cisplatin, with either a combination of cisplatin, doxorubicin, and paclitaxel or a two-drug regimen of paclitaxel plus cisplatin. In squamous cell carcinoma of the cervix, a logical approach to the incorporation of paclitaxel into front-line therapy for advanced or recurrent disease is a phase III trial of the best regimen from GOG protocol 110 (cisplatin with or without either ifosfamide or dibromodulcitol) versus the same drugs plus paclitaxel. In addition, the GOG is conducting a phase I trial of paclitaxel given concomitantly with radiation in the hope that the resulting regimen will be an arm of a future randomized study in patients with locoregionally advanced disease (stages IIB through IVA). The ultimate role of paclitaxel in the management of patients with these two neoplasms awaits the results of these efforts.

Carcinoma of the uterine cervix: current status and future directions.

Based on rigorous interpretation of current evidence, systemic therapy has two roles in the management of carcinoma of the uterine cervix. In patients with advanced or recurrent disease, single-agent chemotherapy constitutes the treatment of choice. The most extensively studied agents are the platinum compounds. Either cisplatin or carboplatin represents a reasonable choice for first-line treatment. There appears to be no significant influence of either dose or schedule on patient benefit. Other agents with clear-cut activity include ifosfamide, dibromodulcitol, and doxorubicin. At this time, there is no scientific basis for the use of combination chemotherapy in advanced or recurrent carcinoma of the cervix. In patients with locoregionally advanced disease (stages IIIB or IVA), radiation plus either hydroxyurea or a combination of cisplatin plus 5-fluorouracil offers an advantage over radiation alone in terms of progression-free interval and survival. In patients with more limited disease, there is no defined role for systemic therapy at the present time. Three goals constitute the focus for current investigational efforts: (1) continued efforts to identify additional highly active drugs are needed; (2) the development of effective combination chemotherapy depends on the use of logically designed combinations of active drugs in well-designed phase III trials with single-agent therapy as the control; and (3) phase III trials seeking more effective combinations of systemic therapy with surgery and/or radiotherapy should continue for not only locoregionally advanced disease but also for more limited carcinoma of the cervix.

Ovarian carcinoma: the role of chemotherapy.

Maximum surgical effort will yield improved survival and response to subsequent therapy in patients with minimal residual disease (less than 2 cm diameter of any remaining nodule). Systemic therapy is the mainstay of later management. Studies have focused on single-agent v combination chemotherapy, optimal combination, dose intensity, and route of administration. In advanced disease, studies of the Gynecologic Oncology Group (GOG) demonstrate the superiority of cisplatin based combination chemotherapy over a single alkylating agent in regard to overall response, clinical complete response, response duration, and survival. Subsequent GOG and other studies suggest that a two-drug combination of cisplatin and cyclophosphamide is therapeutically equivalent to more toxic three- and four-drug combinations. Whether continued escalation of drug dose intensity beyond usual clinical schedules yields incremental gain in benefit remains under study. Administration of drug, particularly cisplatin, via the intraperitoneal (IP) route produces objective responses in patients who have progressed after prior cisplatin based therapy. Whether IP therapy is superior to IV therapy as first-line treatment is under investigation. In limited disease, patients can be assigned to low- and high-risk groups based on careful surgical staging. Patients with low-risk limited disease have a 5-year disease-free survival exceeding 95% with no adjuvant therapy. Those with high-risk disease, even with IP chromic phosphate or systemic melphalan, have a relapse rate of 20% or more after a similar period. The potential role of cisplatin based combination therapy in such patients is under study. Future improvement in results depends on current investigations of noninvasive methods for diagnosis and evaluation, better definition of the value of greater dose intensity and alternate route of administration, the value of methods for choosing appropriate drugs, the development of new agents, and methods to overcome drug resistance.

Chemotherapy in ovarian carcinoma: present role and future prospects.

Epithelial carcinoma of the ovary is characterized by presentation at an advanced stage, spread primarily by an intraperitoneal (IP) route, and relative sensitivity to chemotherapy. An initial surgical approach is essential to proper staging of the disease process and to aggressive cytoreduction, which in turn improves response to chemotherapy and survival. The use of chemotherapy is the mainstay of definitive therapy after completion of the initial surgery. A large number of drugs have activity against the disease, with the most important single category of agents being the platinum compounds. Studies by the Gynecologic Oncology Group (GOG) document the superiority of cisplatin-based combination chemotherapy over single alkylating agents and combinations that do not include cisplatin. The current regimen of choice is a two-drug combination of cisplatin plus cyclophosphamide. Efforts to improve results further focus on enhancing dose intensity of the drug combination through either escalating intravenous (IV) doses or administering cisplatin via an IP route. Also offering an opportunity for further improvement of therapeutic results are three drugs identified as having activity in patients no longer candidates for cisplatin: carboplatin, ifosfamide, and taxol. Biologic agents, such as alpha-interferon, also have potential roles in future combination therapy. The management of patients with limited (stage I or II) disease is based on studies of the GOG and the Ovarian Cancer Study Group, which indicate that this population can be divided by prognostic factors into a group at low risk for recurrence and a group at high risk. Those at low risk require only surgery, whereas those at high risk should receive either IP radioactive chromic phosphate or systemic chemotherapy following surgery. The future prospects for additional improvement of results in all patients appear bright on the basis not only of studies of dose intensity and IP therapy but also of efforts directed at overcoming multidrug resistance and at devising noninvasive means of assessing disease status.

The role of paclitaxel in the management of coelomic epithelial carcinoma of the ovary: a review with emphasis on the Gynecologic Oncology Group experience.

Coelomic epithelial carcinoma of the ovary, the most common cause of death from cancer of the female genital tract in the United States, presents most commonly as advanced (stage III or IV) disease. Management consists of aggressive surgical cytoreduction followed by combination chemotherapy, until recently, a platinum compound plus an alkylating agent. The recent identification of the activity of paclitaxel (Taxol; Bristol-Myers Squibb Company, Princeton, NJ) offers the potential to improve further the management of patients with advanced disease. That this agent might enhance current front-line therapy is supported by its unique mechanism of action and by the significant numbers of responses reported in patients clinically resistant to the platinum compounds: more than 20% of these patients responded to paclitaxel as salvage therapy in four different phase II trials. These observations led to a phase I Gynecologic Oncology Group trial that showed that paclitaxel 135 mg/m2 over 24 hours followed by cisplatin 75 mg/m2 could be given every 3 weeks. This group then compared six cycles of the identified regimen with six cycles of standard cisplatin/cyclophosphamide chemotherapy given every 3 weeks in a phase III trial in 388 previously untreated patients with large-volume (residual nodules > 1 cm after surgery) disease. The results show the superiority of the paclitaxel/cisplatin regimen: overall response rate 77% versus 62%, clinical complete response 54% versus 33%, frequency of achieving a grossly disease-free state at second-look laparotomy 40% versus 22%, progression-free survival 18 versus 13 months, and overall survival 38 versus 24 months. Thus, paclitaxel/cisplatin is the new standard of care for patients with advanced ovarian carcinoma. Current phase III studies explore further the role of paclitaxel in front-line therapy: the relative merits of single-agent versus combination chemotherapy, the role of interval surgical cytoreduction combined with paclitaxel/cisplatin, the value of carboplatin-based versus cisplatin-based combinations with paclitaxel, the significance of the paclitaxel infusion length (3 v 24 v 96 hours), and the value of more dose-intense combinations.

Concurrent chemotherapy and radiotherapy for limited small-cell carcinoma of the lung: a Southwest Oncology Group Study.

This pilot study in limited-stage small-cell carcinoma of the lung using concurrent cisplatin (Platinol) and etoposide (VePesid) chemotherapy with radiotherapy has yielded a high complete response rate in 23 of 40 patients evaluable for response. Five of these responders have survived greater than 2 years off all therapy with a stable, high performance status. Median survival of all patients is 18 months. Toxicity has been acceptable, the most common being neutropenia. Radiation toxicities include 17 of 40 patients experiencing mild to moderate esophagitis, with one severe toxicity; and three of 40 patients developing mild to moderate radiation pneumonitis. The high complete remission observed with this program and the long tumor-free interval seen off maintenance therapy deserve further exploration. Toxicities appear only moderately greater than with other programs currently utilized.

Nutrition, cancer, and aging: an annotated review. II. Cancer cachexia and aging.

The interactions of cancer and malnutrition are discussed with the focus on aging. To establish whether the elderly are more likely to develop cancer cachexia and its complications, this review encompasses the pathogenesis of malnutrition in cancer; the age-related alterations of appetite, gastrointestinal function, energy expenditure, and protein turnover; the diagnosis of malnutrition; and the effectiveness of nutritional support in the elderly. Although metabolic and physiologic changes induced by cancer and age appear synergistic in causing cachexia, more frequent complications of malnutrition have not been observed in the geriatric cancer patients. This may be due to only a small proportion of the elderly with cancer being enrolled in clinical studies or to a reduced cachexia-inducing ability of tumors in these patients. A limited number of studies indicate nutritional replenishment is obtainable in malnourished elderly by hyperalimentation. As restoration of the lean body mass may be slower in older patients, early institution of nutritional support is recommended in malnourished elderly or elderly at risk for malnutrition during neoplastic treatment.

Nutrition, cancer, and aging: an annotated review. I. Diet, carcinogenesis, and aging.

The interrelationships of diet and carcinogenesis are discussed with the focus on aging. To establish whether the elderly are more susceptible to dietary carcinogens and whether dietary prevention of cancer is a reasonable goal for this population, the mechanisms of chemical carcinogenesis, the age-related metabolic and physiologic changes, and the current cancer preventive dietary strategies are reviewed. Vulnerability to dietary carcinogens results from a combination of factors that may increase or decrease the occurrence of cancer in the elderly, and it is, therefore, a very individualized feature, unpredictable when based solely on a subject's age. Dietary prevention of cancer may be effective in advanced age, and the dietary guidelines of the National Academy of Sciences should be implemented in this population.

Ocular albinism and hypopigmentation defects in Slc24a5-/- mice.

As part of a high-throughput mutagenesis and phenotyping process designed to discover novel drug targets, we generated and characterized mice with a targeted mutation in Slc24a5, a gene encoding a putative cation exchanger. Upon macroscopic examination, Slc24a5-/- mice were viable, fertile, and indistinguishable by coat color from their heterozygous and wild-type litter mates. Ophthalmoscopic examination revealed diffuse retinal hypopigmentation, and a histologic examination of the eye confirmed the presence of moderate-to-marked hypopigmentation of the retinal pigmented epithelium (RPE), ciliary body, and iris pigment epithelium (IPE). Hypopigmentation was most severe in the anterior layer cells of the IPE, where melanosomes were smaller, paler, and more indistinct than those of the anterior stroma and posterior IPE. The pigment granules of the posterior IPE appeared to be nearly as dark as those in stromal melanocytes; however, both cell layers were thinner and paler than corresponding layers in wild-type mice. Ultrastructural analysis of the RPE, IPE, and ciliary body pigmented cells confirmed that mutation of Slc24a5 results in marked hypopigmentation of melanosomes in optic cup-derived pigmented neuroepithelium in the eyes. Milder reductions in melanosome size and pigmentation were noted in neural crest-derived melanocytes. The severe hypopigmentation of neuroepithelium-derived cells in the eyes resulted in a novel form of ocular albinism in Slc24a5-/- mice. Our findings suggest that SLC24A5 may be a candidate gene for some forms of ocular albinism and for the BEY1/EYCL2 locus previously associated with central brown eye color in humans.