Comparison of three rapamycin dosing schedules in A/J Tsc2+/- mice and improved survival with angiogenesis inhibitor or asparaginase treatment in mice with subcutaneous tuberous sclerosis related tumors

<p>Abstract</p> <p>Background</p> <p>Tuberous Sclerosis Complex (TSC) is an autosomal dominant tumor disorder characterized by the growth of hamartomas in various organs including the kidney, brain, skin, lungs, and heart. Rapamycin has been shown to reduce the size of kidney angiomyolipomas associated with TSC; however, tumor regression is incomplete and kidney angiomyolipomas regrow after cessation of treatment. Mouse models of <it>TSC2 </it>related tumors are useful for evaluating new approaches to drug therapy for TSC.</p> <p>Methods</p> <p>In cohorts of <it>Tsc2</it>^+/-mice, we compared kidney cystadenoma severity in A/J and C57BL/6 mouse strains at both 9 and 12 months of age. We also investigated age related kidney tumor progression and compared three different rapamycin treatment schedules in cohorts of A/J <it>Tsc2</it>^+/-mice. In addition, we used nude mice bearing <it>Tsc2</it>^-/-subcutaneous tumors to evaluate the therapeutic utility of sunitinib, bevacizumab, vincristine, and asparaginase.</p> <p>Results</p> <p>TSC related kidney disease severity is 5-10 fold higher in A/J <it>Tsc2</it>^+/-mice compared with C57BL/6 <it>Tsc2</it>^+/-mice. Similar to kidney angiomyolipomas associated with TSC, the severity of kidney cystadenomas increases with age in A/J <it>Tsc2</it>^+/-mice. When rapamycin dosing schedules were compared in A/J <it>Tsc2</it>^+/-cohorts, we observed a 66% reduction in kidney tumor burden in mice treated daily for 4 weeks, an 82% reduction in mice treated daily for 4 weeks followed by weekly for 8 weeks, and an 81% reduction in mice treated weekly for 12 weeks. In the <it>Tsc2</it>^-/-subcutaneous tumor mouse model, vincristine is not effective, but angiogenesis inhibitors (sunitinib and bevacizumab) and asparaginase are effective as single agents. However, these drugs are not as effective as rapamycin in that they increased median survival only by 24-27%, while rapamycin increased median survival by 173%.</p> <p>Conclusions</p> <p>Our results indicate that the A/J <it>Tsc2</it>^+/-mouse model is an improved, higher through-put mouse model for future TSC preclinical studies. The rapamycin dosing comparison study indicates that the duration of rapamycin treatment is more important than dose intensity. We also found that angiogenesis inhibitors and asparaginase reduce tumor growth in a TSC2 tumor mouse model and although these drugs are not as effective as rapamycin, these drug classes may have some therapeutic potential in the treatment of TSC related tumors.</p

Rapamycin weekly maintenance dosing and the potential efficacy of combination sorafenib plus rapamycin but not atorvastatin or doxycycline in tuberous sclerosis preclinical models

BACKGROUND: Tuberous sclerosis complex (TSC) is an autosomal dominant tumor suppressor syndrome, characterized by hamartomatous growths in the brain, skin, kidneys, lungs, and heart, which lead to significant morbidity. TSC is caused by mutations in the TSC1 or TSC2 genes, whose products, hamartin and tuberin, form a tumor suppressor complex that regulates the PI3K/Akt/mTOR pathway. Early clinical trials show that TSC-related kidney tumors (angiomyolipomas) regress when treated with the mammalian target of rapamycin (mTOR) inhibitor, rapamycin (also known as sirolimus). Although side effects are tolerable, responses are incomplete, and tumor regrowth is common when rapamycin is stopped. Strategies for future clinical trials may include the investigation of longer treatment duration and combination therapy of other effective drug classes. RESULTS: Here, we examine the efficacy of a prolonged maintenance dose of rapamycin in Tsc2+/- mice with TSC-related kidney tumors. Cohorts were treated with rapamycin alone or in combination with interferon-gamma (IFN-g). The schedule of rapamycin included one month of daily doses before and after five months of weekly doses. We observed a 94.5% reduction in kidney tumor burden in Tsc2+/- mice treated (part one) daily with rapamycin (8 mg/kg) at 6 months ≤ age \u3c 7 months, (part 2) weekly with rapamycin (16 mg/kg) at 7 months ≤ age \u3c 12 months, and (part 3) daily with rapamycin (8 mg/kg) at 12 months ≤ age \u3c 13 months; but we did not observe any improvement with combination IFN-g plus rapamycin in this study. We also used a Tsc2-/- subcutaneous tumor model to evaluate other classes of drugs including sorafenib, atorvastatin, and doxycycline. These drugs were tested as single agents and in combination with rapamycin. Our results demonstrate that the combination of rapamycin and sorafenib increased survival and may decrease tumor volume as compared to rapamycin treatment alone while sorafenib as a single agent was no different than control. Atorvastatin and doxycycline, either as single agents or in combination with rapamycin, did not improve outcomes as compared with controls. CONCLUSION: Our results indicate that prolonged treatment with low doses of mTOR inhibitors may result in more complete and durable TSC-related tumor responses, and it would be reasonable to evaluate this strategy in a clinical trial. Targeting the Raf/Mek/Erk and/or VEGF pathways in combination with inhibiting the mTOR pathway may be another useful strategy for the treatment of TSC-related tumors

Carbamazepine-Associated Hyponatremia

Four cases of CBZ-induced or exacerbated hyponatremia are described in middle-aged to elderly females. Two cases are remarkable in that the pretreatment sodium levels demonstrate hyponatremia. A return to prior sodium levels was observed upon the discontinuation of carbamazepine therapy. No definitive conclusions can be drawn from these case reports; however, similarities in the cases can be examined as follows: (1) all four women have medical problems, in particular two patients had pre-existing hyponatremia; (2) all four patients were using concurrent medications; (3) all four women presented psychotic. A literature review examines risk factors, pharmacological mechanism, and the time course for CBZ-induced hyponatremia

Topical rapamycin inhibits tuberous sclerosis tumor growth in a nude mouse model

<p>Abstract</p> <p>Background</p> <p>Skin manifestations of Tuberous Sclerosis Complex (TSC) cause significant morbidity. The molecular mechanism underlying TSC is understood and there is evidence that systemic treatment with rapamycin or other mTOR inhibitors may be a useful approach to targeted therapy for the kidney and brain manifestations. Here we investigate topical rapamycin in a mouse model for TSC-related tumors.</p> <p>Methods</p> <p>0.4% and 0.8% rapamycin ointments were applied to nude mice bearing subcutaneous, TSC-related tumors. Topical treatments were compared with injected rapamycin and topical vehicle. Rapamycin levels in blood and tumors were measured to assess systemic drug levels in all cohorts.</p> <p>Results</p> <p>Treatment with topical rapamycin improved survival and reduced tumor growth. Topical rapamycin treatment resulted in systemic drug levels within the known therapeutic range and was not as effective as injected rapamycin.</p> <p>Conclusion</p> <p>Topical rapamycin inhibits TSC-related tumor growth. These findings could lead to a novel treatment approach for facial angiofibromas and other TSC skin lesions.</p

Multicenter Phase 2 Trial of Sirolimus for Tuberous Sclerosis: Kidney Angiomyolipomas and Other Tumors Regress and VEGF- D Levels Decrease

Tuberous sclerosis (TSC) related tumors are characterized by constitutively activated mTOR signaling due to mutations in TSC1 or TSC2.We completed a phase 2 multicenter trial to evaluate the efficacy and tolerability of the mTOR inhibitor, sirolimus, for the treatment of kidney angiomyolipomas.36 adults with TSC or TSC/LAM were enrolled and started on daily sirolimus. The overall response rate was 44.4% (95% confidence intervals [CI] 28 to 61); 16/36 had a partial response. The remainder had stable disease (47.2%, 17/36), or were unevaluable (8.3%, 3/36). The mean decrease in kidney tumor size (sum of the longest diameters [sum LD]) was 29.9% (95% CI, 22 to 37; n = 28 at week 52). Drug related grade 1-2 toxicities that occurred with a frequency of >20% included: stomatitis, hypertriglyceridemia, hypercholesterolemia, bone marrow suppression (anemia, mild neutropenia, leucopenia), proteinuria, and joint pain. There were three drug related grade 3 events: lymphopenia, headache, weight gain. Kidney angiomyolipomas regrew when sirolimus was discontinued but responses tended to persist if treatment was continued after week 52. We observed regression of brain tumors (SEGAs) in 7/11 cases (26% mean decrease in diameter), regression of liver angiomyolipomas in 4/5 cases (32.1% mean decrease in longest diameter), subjective improvement in facial angiofibromas in 57%, and stable lung function in women with TSC/LAM (n = 15). A correlative biomarker study showed that serum VEGF-D levels are elevated at baseline, decrease with sirolimus treatment, and correlate with kidney angiomyolipoma size (Spearman correlation coefficient 0.54, p = 0.001, at baseline).Sirolimus treatment for 52 weeks induced regression of kidney angiomyolipomas, SEGAs, and liver angiomyolipomas. Serum VEGF-D may be a useful biomarker for monitoring kidney angiomyolipoma size. Future studies are needed to determine benefits and risks of longer duration treatment in adults and children with TSC.Clinicaltrials.gov NCT00126672

Rapamycin levels in tumor samples after treatment with topical or IP rapamycin

Rapamycin levels in tumor homogenates from indicated treatment groups were measured 24 hours (A, C) and 48 hours (B, D) after the final dose of rapamycin. Panels C and D are enlarged versions of the boxed-in data in panels A and B respectively.<p><b>Copyright information:</b></p><p>Taken from "Topical rapamycin inhibits tuberous sclerosis tumor growth in a nude mouse model"</p><p>http://www.biomedcentral.com/1471-5945/8/1</p><p>BMC Dermatology 2008;8():1-1.</p><p>Published online 28 Jan 2008</p><p>PMCID:PMC2266897.</p><p></p

Rapamycin whole blood levels after treatment with topical and IP rapamycin

A) Whole blood rapamycin levels from tumor bearing animals from indicated treatment groups. Rapamycin levels were measured 24 hours after the final dose of rapamycin. B) Whole blood rapamycin levels were measured in cohorts of control mice with no tumors. As indicated, levels were measured 24 hours after either one or three doses of topical rapamycin. In some groups, Elizabethan collars or bandages were used to prevent ingestion of rapamycin ointment. All animals had rapamycin levels >3 ng/ml. The slightly higher levels in the Elizabethan collar group suggests that ingestion is not a major issue. The lower levels in the bandage groups suggests that the bandage polymer can affect drug absorption. C) Whole blood rapamycin levels were also measured 48 hours after the final dose in tumor bearing animals. D) In three of the control, non-tumor bearing groups, rapamycin levels were measured at 48 hours following their final treatment to compare to tumor bearing animals.<p><b>Copyright information:</b></p><p>Taken from "Topical rapamycin inhibits tuberous sclerosis tumor growth in a nude mouse model"</p><p>http://www.biomedcentral.com/1471-5945/8/1</p><p>BMC Dermatology 2008;8():1-1.</p><p>Published online 28 Jan 2008</p><p>PMCID:PMC2266897.</p><p></p

Tuberous sclerosis preclinical studies: timing of treatment, combination of a rapamycin analog (CCI-779) and interferon-gamma, and comparison of rapamycin to CCI-779-1

<p><b>Copyright information:</b></p><p>Taken from "Tuberous sclerosis preclinical studies: timing of treatment, combination of a rapamycin analog (CCI-779) and interferon-gamma, and comparison of rapamycin to CCI-779"</p><p>http://www.biomedcentral.com/1471-2210/7/14</p><p>BMC Pharmacology 2007;7():14-14.</p><p>Published online 6 Nov 2007</p><p>PMCID:PMC2213639.</p><p></p

Tuberous sclerosis preclinical studies: timing of treatment, combination of a rapamycin analog (CCI-779) and interferon-gamma, and comparison of rapamycin to CCI-779-0

<p><b>Copyright information:</b></p><p>Taken from "Tuberous sclerosis preclinical studies: timing of treatment, combination of a rapamycin analog (CCI-779) and interferon-gamma, and comparison of rapamycin to CCI-779"</p><p>http://www.biomedcentral.com/1471-2210/7/14</p><p>BMC Pharmacology 2007;7():14-14.</p><p>Published online 6 Nov 2007</p><p>PMCID:PMC2213639.</p><p></p>eived 8 mg/kg CCI-779 and 20,000 units IFN-γ by IP injection Monday through Friday for two months at the indicated ages. Severity of kidney disease was quantified both by counting the total number of cystadenomas and by scoring all the cystadenomas found. Average number of cystadenomas per kidney for indicated treatment cohort shown in bar graph (a) and table (c) format. Average cystadenoma score per kidney for indicated treatment cohort shown in bar graph (b) and table (d) format. Red error bars denote a statistically significant difference (P < 0.05) relative to untreated. "Both" in panels a-d refers to a combination of CCI-779 and IFN-γ. To illustrate the timing of kidney lesion genesis in untreated mice, graphs of average number of cystadenomas per kidney (e) and average cystadenoma score per kidney (f) are shown for cohorts of mice at different ages (3, 7 and 11 months; n = 6 mice for each age cohort). The asterisks in panels e and f indicate that the severity of kidney disease in untreated cohorts at 3 months and 11 months differs significantly from disease severity at 7 months (t-test, P ≤ 0.05)