Pediatr Blood Cancer 2010;54:476–479
`
`BRIEF REPORT
`Rapamycin (Sirolimus) in Tuberous Sclerosis Associated
`Pediatric Central Nervous System Tumors
`
`Catherine Lam, MD,1 Eric Bouffet, MD,1* Uri Tabori, MD,1 Donald Mabbott, MD,2
`1
`Michael Taylor, MD, PhD,3 and Ute Bartels, MD
`
`Tuberous sclerosis complex (TSC) is associated with hamartom-
`atous growths including subependymal giant cell astrocytomas
`(SEGAs). Since chemo-radiation therapies offer
`scant benefit,
`oncologists had traditionally been little involved in managing
`SEGAs. Recent evidence demonstrating rapamycin efficacy in adults
`
`and children with TSC-associated tumors foresee a practice change.
`We summarize our institutional experience and literature review that
`highlight potential benefits and hazards of rapamycin therapy, for
`TSC patients with SEGA, and other syndromal brain tumors. Pediatr
`Blood Cancer 2010;54:476–479. ß 2009 Wiley-Liss, Inc.
`
`Key words: mTOR; rapamycin; sirolimus; subependymal giant cell astrocytoma; tuberous sclerosis complex
`
`INTRODUCTION
`
`Tuberous sclerosis complex (TSC) is an autosomal dominant
`disorder caused by inactivating mutations in the tumor suppressor
`genes hamartin (TSC1) or tuberin (TSC2), associated with potential
`hamartomatous tumors. Approximately, 10% of TSC patients
`develop low-grade CNS lesions known as subependymal giant cell
`astrocytoma (SEGA) [1]. SEGAs are challenging tumors; slow-
`growing with often no symptoms until obstructive hydrocephalus
`develops; watchful monitoring and early surgical intervention have
`been traditional mainstays of therapy. There is sparse evidence of
`spontaneous regression or growth stabilization; radiotherapy or
`chemotherapy typically would not halt progression [2]. Up to now,
`oncologists were rarely involved in managing TSC. Recent
`evidence suggesting rapamycin efficacy in patients with TSC-
`associated tumors may predict changing practice. We present three
`pediatric patients with TSC and large SEGA treated with
`rapamycin, and discuss potential implications of these findings.
`
`CASES
`
`Case 1
`
`A 9-year-old diagnosed with nonfamilial TSC at 3 months was
`referred after a routine MRI disclosed an increasing SEGA. His
`history included stable renal angiomyolipomas and well-controlled
`complex partial seizures; he was in grade-appropriate schooling
`with educational assistance. A right-sided SEGA detected at age 2
`on routine MRI had remained small at age 4. Rapamycin was started
`after his MRI at age 9 showed tumor progression, associated with
`ventriculomegaly without symptoms. After loading with 5 mg TID,
`he started 5 mg daily, titrated to 7 mg daily while on carbamazepine
`(known to induce rapamycin metabolism), with trough levels
`between 10 and 15 ng/ml. Follow-up MRI demonstrated a 65%
`SEGA decrease 3 months after
`rapamycin initiation from
`35 24 34 mm before therapy (Fig. 1A) to 24 16 26 mm
`(Fig. 1B) with near-resolution of hydrocephalus; unchanged at 6 and
`9 months follow-up. He had intermittent oral ulcers and myalgias,
`transient hypercholesterolemia, and gingival hypertrophy that
`responded to dental brace readjustment. His facial angiofibromas
`decreased significantly on rapamycin. It was elected to stop
`rapamycin after 1 year. Unfortunately, regrowth was noted 3 months
`after rapamycin discontinuation (Fig. 1C) and rapamycin was
`ß 2009 Wiley-Liss, Inc.
`DOI 10.1002/pbc.22298
`Published online 23 October 2009 in Wiley InterScience
`(www.interscience.wiley.com)
`
`restarted. His 3-month follow-up MRI again demonstrated reduced
`SEGA size.
`
`Case 2
`
`A 13-year-old with TSC was referred after an increasing
`SEGA was noted. A twin without familial TSC, TSC was diagnosed
`at age 7 after dizziness and a falls prompted a head CT scan that
`demonstrated tubers. Renal angiomyolipomas and cardiac rhabdo-
`myomas were subsequently shown. A SEGA at the right foramen of
`Monro was noted at age 9. Routine neuroimaging at age 13 detected
`significant SEGA growth and symptom review found mild
`intermittent headaches. After a 15 mg loading dose, he started
`6 mg rapamycin daily, with maximum trough of 14 ng/ml. Head-
`aches improved within 1 month, with occasional mouth sores and
`mild transient hypercholesterolemia. Three-month follow-up MRI
`showed a 60% SEGA decrease.
`
`Case 3
`
`A 10-year-old with TSC underwent evaluation for headaches and
`MRI revealed a large SEGA in the left foramen of Monro with
`significant hydrocephalus. She had a history of developmental delay
`and well-controlled epilepsy on phenytoin. Routine neuroimaging
`at age 3 and 7 demonstrated subcentimeter SEGAs with mild
`stable ventriculomegaly. At diagnosis of her large SEGA, chronic
`papilledema was noted;
`there were no symptoms apart from
`progressive headaches and propensity for car-sickness. Rapamycin
`was started,
`titrated to 9 mg daily. Three-month follow-up
`MRI showed 50% SEGA decrease and ventriculomegaly improved.
`Initial mouth sores self-resolved; maximum trough was 8.4 ng/ml.
`Three months after
`rapamycin initiation, papilledema and
`
`——————
`1Division of Haematology/Oncology, Neuro-oncology Program, The
`2Department of
`Hospital
`for Sick Children, Toronto, Canada;
`Psychology, The Hospital
`for Sick Children, Toronto, Canada;
`3Division of Neurosurgery, The Hospital for Sick Children, Toronto,
`Canada
`
`*Correspondence to: Eric Bouffet, Division of Haematology/
`Oncology, The Hospital for Sick Children, 555 University Avenue,
`Toronto, Canada M5G 1X8. E-mail: eric.bouffet@sickkids.ca
`
`Received 21 July 2009; Accepted 25 August 2009
`
`Ex. 1099-0001
`
`

`
`CNS tumors and rapamycin
`
`477
`
`lymphangiomatosis, rapamycin resulted in significant shrinkage
`[6,7].
`Rapamycin levels for antitumor effects are currently based on
`levels used for immunosuppression, aiming for 24 hr trough levels
`between 10 and 15 ng/ml. However, antitumor activity may occur at
`lower levels, as in Case 3, where response occurred with maximum
`trough of 8.4 ng/ml. Avoidance of adverse effects and consideration
`of drug interactions require ongoing attention [2].
`
`Potential Limitations to Rapamycin Effect and/or Use
`
`Side effects include oral ulcers, acneiform rash, arthralgias, and
`diarrhea, thrombocytopenia, hyperlipidemia, and lipoproteinemia
`[2]. Side effects appear generally self-limited, but may require
`temporary dose reduction or cessation [7]. There are, however,
`sequelae of impaired wound healing and immunosuppression,
`including opportunistic infections and lymphoproliferative disease
`in transplant populations [2]. Notably, anticancer properties of
`rapamycin appear dominant to its immunosuppressant effects [4],
`and rapamycin is thought to hold a more favorable profile than other
`immunosuppressants including reduced post-transplant malignan-
`cies [13]. Continuous mTOR inactivation may also affect negative
`feedback loops involving upstream AKT/PI3K signaling; as
`activated PI3K often associates with more aggressive tumors, this
`warrants monitoring for malignant transformation with mTOR
`inhibition [14]. In vivo rapamycin resistance has been suggested
`from animal models [5]. This argues for potential need for
`combination therapies to maximize efficacy.
`
`Indications for Rapamycin in Other CNS Tumors
`
`Increased mTOR pathway activity has been demonstrated in
`tumors in the setting of neurofibromatosis type-1 (NF1). Increased
`ribosomal S6 activity was shown in mutant Nf1 mouse optic gliomas
`and human NF1-associated pilocytic astrocytomas, with abnormal
`astrocytes’ increased growth arrested upon mTOR inhibition [15].
`Rapamycin is currently assessed in NF1-associated plexiform
`neurofibromas in children (http://www.cancer.gov/CLINICAL-
`TRIALS. Accessed July 1, 2009).
`Most rapamycin trials in CNS tumors have involved high-grade
`glioma (HGG) patients. A phase I study of neoadjuvant rapamycin
`in recurrent PTEN-deficient glioblastoma patients found reduced
`tumor proliferation in 7 of 14 patients [14]. Other adult studies
`have combined rapamycin with molecularly targeted agents such
`as EGFR inhibitors [16] or erlotinib (http://www.cancer.gov/
`CLINICALTRIALS. Accessed July 1, 2009).
`
`Other mTOR Inhibitors
`
`in other small-
`Rapamycin results have triggered interest
`molecule therapies in oncology,
`including derivative mTOR
`1
`inhibitors, everolimus (RAD001; Certican
`) and temsirolimus
`(CCI-779; ToriselTM). These analogs inhibit mTORC2 and thereby
`impair AKT signaling and cell survival [17].
`A phase I pediatric study of everolimus has demonstrated
`acceptable safety [17]. A phase III study on SEGAs in TSC is
`pending (Protocol IDs CRAD001M2301, NCT00789828), as is a
`phase II pediatric chemotherapy-resistant low-grade glioma study.
`Adult CNS tumor trials underway include: phase I/II chemo-
`radiation trial in new glioblastoma; and phase II trials in recurrent
`
`Fig. 1. A: Baseline pre-rapamycin (axial T1 MRI); B: Response after
`3 months of rapamycin (axial T1 MRI); C: Regrowth after stopping
`rapamycin for 3 months (axial T1 MRI).
`
`headaches had resolved, and adenoma sebaceum lesions had
`significantly improved.
`
`DISCUSSION
`
`mTOR and TSC
`
`Mammalian target of rapamycin (mTOR) is an evolutionarily
`conserved cytoplasmic serine/threonine kinase involved in cell
`growth and metabolism [3]. Survival and growth promotion through
`mTOR signaling is mediated by the mTOR complex (mTORC),
`which phosphorylates and upregulates ribosomal S6 kinases,
`inducing cell growth and protein translation, and downregulates
`4E binding proteins which inhibit protein translation [1]. TSC1/
`TSC2 regulate mTOR activity by inhibiting Rheb, a key mTOR
`activator through the AKT pathway. Upon recognizing inactivating
`TSC1/TSC2 mutations that led to constitutive mTOR activity and
`tumorigenesis, thereby resulting in TSC [2], many postulated that
`mTOR inhibitors would be ideal contributors to TSC therapy.
`1
`Rapamycin (sirolimus; Rapamune
`) was initially identified as an
`antimicrobial agent, but became best established as transplant
`immunosuppressive therapy [4]. Rapamycin can complex with
`FK506 binding protein-12 (FKBP12) and inhibit mTOR’s phos-
`phorylation activity, leading to cell size reduction or apoptosis [5].
`Rapamycin also inhibits tumor angiogenesis [4]. Rapamycin has
`thus been a study target in multiple tumors,
`including TSC-
`associated ones, and in diverse disorders, from coronary artery
`disease to various common cancers [3–5].
`
`Indications for Rapamycin in TSC
`
`Early clinical studies support rapamycin efficacy in TSC tumors
`of the CNS, kidneys, and lungs [3,6,7]. Our cases, together with
`cases summarized (Table I), suggest dramatic response of TSC-
`associated CNS tumors to rapamycin, pointing to a potentially
`alternative to surgery [2,8]. As in other tumors, SEGA tissue showed
`that biallelic TSC1/TSC2 loss results in mTOR activation [9]. In
`addition, rapamycin showed promising efficacy in preventing
`seizures, and prolonging survival along with potentially improving
`learning/behavioral deficits in mouse TSC models [10,11]. Other
`rodent models’ studies have,
`in contrast, suggested memory
`impairment [12]. Unfortunately, our patients did not undergo
`serial neuropsychologic testing during treatment. Potential neuro-
`psychologic consequences require further delineation, although
`there are no definitive clinical concerns in human trials to date
`[7]. Rapamycin’s activity outside the CNS has also been suggested.
`In adult, TSC-associated renal angiomyolipomas and sporadic
`
`Pediatr Blood Cancer DOI 10.1002/pbc
`
`Ex. 1099-0002
`
`

`
`[8]
`Koenigetal.
`
`Symptomsimproved;decreasedsizeat2.5months
`
`None
`
`0.2mg/kg/day;11–13ng/ml
`
`Intermittentheadaches,
`
`21;F;bilateralSEGA;TSC
`
`Adultcases(>18years)
`
`5.67.3mm,(0.25cm3)(L)
`4.39.5mm,(0.61cm3)(R)
`
`6.610.3mm,(1cm3)(L)
`13.210.7mm,(1.6cm3)(R)
`
`Franzetal.[2]
`
`4monthsafterstopping;decreased4monthsafterresumingandat
`
`5months(asymptomatic,mildsideeffects);sizere-increased
`Symptomsresolved;decreasedsizeat2.5/5months;stoppedat
`
`20months
`
`5mm(L)
`7.5mm(R)
`
`8mm(L)
`11mm(R)
`
`(self-resolved)
`elevation
`resumed;cholesterol
`notrecurrentwhen
`formrashat5months:
`
`Aphthousulcers,acnei
`
`F,female;L,left;M,male;mo,month;R,right;wk,week.
`
`6mg;7.7ng/ml
`
`Headaches,withtumor
`
`21;F;bilateralSEGA;TSC
`
`ventriculo-megaly
`growthandmild
`
`(TSC2:10bpdeletion)
`
`growth
`imbalance,withtumor
`blurredvision,and
`
`478
`
`Lam et al.
`
`Franzetal.[2]
`
`Symptomsimproved;decreasedsizeat5monthsMRI;remained
`
`Elevatedcholesterol(no
`
`seizure-free
`
`required)
`therapychange
`
`andlamotrigine
`
`concurrentphenobarbital
`2–7mg;10.9ng/ml;
`
`growth
`movements,withtumor
`nystagmoideye
`
`Progressiveheadache,
`
`References
`
`Sizeatlastfollow-up
`
`Sizepre-rapamycin
`
`Adverseeffects
`
`therapy
`
`Indicationforrapamycin
`
`Response/durationoffollow-up
`
`dailydose/trough/concurrent
`
`Startingdailydose/target
`
`mutation)
`epilepsy;TSC(TSC2:point
`hemorrhage);complexpartial
`resectedat9monthswith
`15;F;SEGA(contralateral
`Pediatriccases(0–18years)
`
`genotype
`diagnosis/underlyingcondition/
`Age(years)/sex(M/F)/tumor
`
`TABLEI.CaseReportsofRapamycininCNSTumors
`
`Pediatr Blood Cancer DOI 10.1002/pbc
`
`Franzetal.[2]
`
`Decreasedsize(solidandcystic)at2.5monthsMRI
`
`Mildacneiformrash,oral
`
`3–6mg;10.4ng/ml
`
`weanedvigabatrin
`
`concurrenttopiramateand
`Titratedto4mg;10.2ng/ml;
`
`drocephalus
`16months,withhy
`hypothalamicmassover
`
`partialepilepsy;TSC
`biopsy);infantilespasmand
`astrocytoma(endoscopic
`
`Progressivelyenlarged
`
`3;F;low-gradepilocytic
`
`growthover9months
`
`Solidandcystictumor
`
`TSC(TSC2:pointmutation)
`
`mildcognitiveimpairment;
`child,off-anticonvulsants;
`spasmsandseizuresas
`14.5;M;SEGAinfantile
`
`amitriptyline
`
`quetiapine,and
`
`sodium,clonidine,
`
`concurrentdivalproex
`2–5mg;9.6ng/ml;
`
`withtumorgrowth
`mentalstatuschange,
`
`Intermittentheadacheand
`
`andbehavioralproblems;TS
`5.5;M;SEGAseizures;sleep
`
`584238mm
`
`665043mm
`
`Franzetal.[2]
`
`withspeechandrehabilitativetherapy
`
`6months;remainedseizure-freetaperedoffvigabatrin;progressed
`ventriculomegalywithdecreasedlesionandfurthernecrosisat5/
`Decreasedventriculomegalywithlesionnecrosisat5-week;resolved
`
`8.113.7mm,(1.7cm3)
`
`13.723.4mm,(3.6cm3)
`
`related)
`(?hydro-cephalus
`irritability
`changerequired)initial
`terol-emia(notherapy
`
`Transienthyper-choles
`
`(resolvedovertime)
`hypercholesterolemia
`ulcers,andtransient
`
`7.39.9mm,(0.41cm3)
`
`10.212.7mm,(1.1cm3)
`
`Franzetal.[2]
`
`Unchangedsleep/behavior;decreasedsizeat3monthsMRI;seizures
`
`None
`
`wellcontrolled
`
`1813mm,(2.4cm3)
`
`2320mm,(6cm3)
`
`Ex. 1099-0003
`
`

`
`glioblastoma and refractory low-grade glioma (http://www.cancer.-
`gov/CLINICALTRIALS. Accessed July 1, 2009).
`Temsirolimus’ use in CNS tumors has included an open-label
`trial of 65 adults with recurrent glioblastoma multiforme, showing
`prolonged time to progression; response correlated with S6 kinase
`activation, suggesting a response mechanism resembling that in
`TSC [18]. A parallel adult phase II trial in 43 recurrent glioblastoma
`multiforme patients found good tolerance but no longer-term
`efficacy [19]. Other trials combining temsirolimus with sorafenib or
`bevacizumab in recurrent HGG are ongoing (http://www.cancer.-
`gov/CLINICALTRIALS. Accessed July 1, 2009).
`
`FUTURE DIRECTIONS
`
`mTOR inhibitors have sparked a potential re-thinking of the
`management of TSC patients. Studies need to confirm rapamycin’s
`efficacy in SEGAs, and its impact on outcomes including neuro-
`psychologic function. Currently,
`it
`is unclear whether mTor
`inhibitors are able to obviate or defer the need for surgical resection
`of symptomatic SEGAs. Studies are required to explore optimal
`therapy duration and management upon discontinuing therapy,
`given reports, including Case 1 above, that suggest re-growth of
`SEGAs upon rapamycin discontinuation. mTOR inhibitors may
`also serve as initial treatment to facilitate surgery for unresectable
`SEGAs.
`
`CONCLUSION
`
`Rapamycin offers significant promise in treating SEGAs and
`other TSC-associated tumors. Results from these three children with
`TSC treated with rapamycin further support rapamycin’s role in
`potentially leading a changing standard of care in TSC. Further
`prospective, longer-term clinical investigations are warranted. Still,
`it is perhaps well time that pediatric neuro-oncologists assume more
`active roles in the multidisciplinary care for TSC patients.
`
`REFERENCES
`
`1. Curatolo P, Bombardieri R, Jozwiak S. Tuberous sclerosis. Lancet
`2008;372:657–668.
`2. Franz DN, Leonard J, Tudor C, et al. Rapamycin causes regression
`of astrocytomas in tuberous sclerosis complex. Ann Neurol 2006;
`59:490–498.
`3. Paul E, Thiele E. Efficacy of sirolimus in treating tuberous sclerosis
`and lymphangioleiomyomatosis. N Engl J Med 2008;358:190–
`192.
`
`CNS tumors and rapamycin
`
`479
`
`4. Law BK. Rapamycin: An anti-cancer immunosuppressant? Crit
`Rev Oncol Hematol 2005;56:47–60.
`5. Kenerson H, Dundon TA, Yeung RS. Effects of rapamycin in the
`Eker rat model of tuberous sclerosis complex. Pediatr Res 2005;
`57:67–75.
`6. Bissler JJ, McCormack FX, Young LR, et al. Sirolimus for
`angiomyolipoma in tuberous sclerosis complex or lymphangio-
`leiomyomatosis. N Engl J Med 2008;358:140–151.
`7. Davies DM, Johnson SR, Tattersfield AE, et al. Sirolimus therapy in
`tuberous sclerosis or sporadic lymphangioleiomyomatosis. N Engl
`J Med 2008;358:200–203.
`8. Koenig MK, Butler IJ, Northrup H. Regression of subependymal
`giant cell astrocytoma with rapamycin in tuberous sclerosis
`complex. J Child Neurol 2008;23:1238–1239.
`9. Chan JA, Zhang H, Roberts PS, et al. Pathogenesis of tuberous
`sclerosis subependymal giant cell astrocytomas: Biallelic inacti-
`vation of TSC1 or TSC2 leads to mTOR activation. J Neuropathol
`Exp Neurol 2004;63:1236–1242.
`10. Ehninger D, Han S, Shilyansky C, et al. Reversal of learning deficits
`in a Tsc2þ/ mouse model of tuberous sclerosis. Nat Med 2008;
`14:843–848.
`11. Zeng LH, Xu L, Gutmann DH, et al. Rapamycin prevents epilepsy
`in a mouse model of tuberous sclerosis complex. Ann Neurol
`2008;63:444–453.
`12. Tischmeyer W, Schicknick H, Kraus M, et al. Rapamycin-sensitive
`signalling in long-term consolidation of auditory cortex-dependent
`memory. Eur J Neurosci 2003;18:942–950.
`13. Monaco AP. The role of mTOR inhibitors in the management of
`posttransplant malignancy. Transplantation 2009;87:157–163.
`14. Cloughesy TF, Yoshimoto K, Nghiemphu P, et al. Antitumor
`activity of rapamycin in a Phase I trial for patients with recurrent
`PTEN-deficient glioblastoma. PLoS Med 2008;5:e8.
`15. Dasgupta B, Yi Y, Chen DY, et al. Proteomic analysis reveals
`hyperactivation of the mammalian target of rapamycin pathway in
`neurofibromatosis 1-associated human and mouse brain tumors.
`Cancer Res 2005;65:2755–2760.
`16. Doherty L, Gigas DC, Kesari S, et al. Pilot study of the combination
`of EGFR and mTOR inhibitors in recurrent malignant gliomas.
`Neurology 2006;67:156–158.
`17. Fouladi M, Laningham F, Wu J, et al. Phase I study of everolimus in
`pediatric patients with refractory solid tumors. J Clin Oncol 2007;
`25:4806–4812.
`18. Galanis E, Buckner JC, Maurer MJ, et al. Phase II trial of
`temsirolimus (CCI-779) in recurrent glioblastoma multiforme: A
`North Central Cancer Treatment Group Study. J Clin Oncol 2005;
`23:5294–5304.
`19. Chang SM, Wen P, Cloughesy T, et al. Phase II study of CCI-779 in
`patients with recurrent glioblastoma multiforme. Invest New Drugs
`2005;23:357–361.
`
`Pediatr Blood Cancer DOI 10.1002/pbc
`
`Ex. 1099-0004