dacarbazine in solitary fibrous tumor: a case series ...speciﬁc pdgfrb (cat: sc 432, santa cruz...

Cancer Therapy: Clinical

Dacarbazine in Solitary Fibrous Tumor: A Case SeriesAnalysis and Preclinical Evidence vis-�a-vis Temozolomideand Antiangiogenics

S. Stacchiotti1, M. Tortoreto2, F. Bozzi3, E. Tamborini3, C. Morosi4, A. Messina4, M. Libertini1, E. Palassini1,D. Cominetti2, T. Negri3, A. Gronchi5, S. Pilotti3, N. Zaffaroni2, and P.G. Casali1

AbstractPurpose: To explore the value of triazines in solitary fibrous tumor (SFT).

Experimental Design:We retrospectively reviewed 8 cases of patients with SFT treated with dacarbazine

(1,200mg/m2 every 3weeks) as from January 2012. Then,we studied a dedifferentiated-SFT subcutaneously

xenotransplanted into severe combined immunodeficient (SCID) mice. Dacarbazine, temozolomide,

sunitinib, bevacizumab, and pazopanib were administered at their reported optimal doses for the mouse

model whenmean tumor volume (TV)was about 80mm3; each experimental groups included 6mice.Drug

activity was assessed as tumor volume inhibition percentage (TVI%). Dacarbazine was tested according to

two different schedules of administration. One hunded twenty days after treatment interruption, mouse

tumor samples were analyzed.

Results: Among the eight patients treated with dacarbazine, best response evaluation criteria in solid

tumors responses (RECIST) were three partial responses, 4 stable disease, 1 progression. Two responsive

patients had paraneoplastic hypoglycemia that disappeared after 10 days from starting dacarbazine. In the

dedifferentiated-SFT xenograft model, dacarbazine and temozolomide showed the highest antitumor

activity (about 95% TVI), confirmed pathologically. Sunitinib and pazopanib were only marginally active

(52% and 41% TVI, respectively), whereas bevacizumab caused a 78% TVI. No tumor regrowth was

observed up to 100 days from end of treatment with temozolomide and dacarbazine, whereas secondary

progression followed sunitinib, pazopanib, and bevacizumab interruption.

Conclusions:Dacarbazine as single agent has antitumor activity in SFT. Our preclinical results suggest a

cytotoxic effect of temozolomide and dacarbazine, as compared with a cytostatic role for sunitinib,

pazopanib, and bevacizumab. A phase II study on dacarbazine in advanced SFT is planned. Clin Cancer

Res; 19(18); 5192–201. �2013 AACR.

IntroductionSolitary fibrous tumor (SFT) is a rare soft-tissue sarcoma

(STS), marked by the presence of a recurrent NAB2-STAT6gene fusion, which was recently identified (1, 2). "Typical"

SFT canbe cured in themajorityof cases by complete surgicalresection, whereas they have a 10%–15% risk of metastasesin the "malignant" presentations (MSFT), or higher in thepleomorphic/dedifferentiated (DSFT) variant (1). Amedicaltreatment is required in case of locally advanced or meta-static disease.

No prospective studies on the activity of chemotherapyin SFT are available. Few retrospective series showed a lowresponse rate (RR) to standard anthracycline-based che-motherapy, ranging between 0% and 20% (3, 4). Fewresponses in patients treatedwith anthracycline plus dacar-bazineþ/� ifosfamide are also reported (5, 6). A higher RRcan be observed in histologically more aggressive DSFTcases (7).

In the last years, the activity of new targeted agents suchas sorafenib, sunitinib, bevacizumab plus temozolomide,pazopanib, insulin-like growth factor (IGF)-1R inhibitorswas described (8–15). In all cases, responses were mostlynondimensional. In particular, researchers from the Uni-versity of TexasMDAnderson Cancer Center (Houston, TX)observed 2 partial responses (PR) and 12 stable diseases

Authors'Affiliations: 1Adult SarcomaMedicalOncologyUnit, Departmentof Cancer Medicine; 2Molecular Pharmacology Unit, Department of Exper-imental Oncology and Molecular Medicine; 3Experimental MolecularPathology Unit, Department of Pathology; 4Department of Radiology; and5Department of Surgery, Fondazione IRCCS Istituto Nazionale Tumori,Milan, Italy

Note: Supplementary data for this article are available at Clinical CancerResearch Online (http://clincancerres.aacrjournals.org/).

Prior presentation: Presented at the 17th AnnualMeeting of theConnectiveSoft Tissue Oncology Society (CTOS), Prague, November 2012

Corresponding Author: Dr. S. Stacchiotti, Fondazione IRCCS IstitutoNazionale dei Tumori, via Venezian 1, Milan 20133, Italy. Phone:00390223902182; Fax: 00390223902804; E-mail:[email protected]

doi: 10.1158/1078-0432.CCR-13-0776

�2013 American Association for Cancer Research.

ClinicalCancer

Research

Clin Cancer Res; 19(18) September 15, 20135192

on February 18, 2021. © 2013 American Association for Cancer Research. clincancerres.aacrjournals.org Downloaded from

Published OnlineFirst July 25, 2013; DOI: 10.1158/1078-0432.CCR-13-0776

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(SD) by response evaluation criteria in solid tumor (RECIST;ref. 16) in 14 patients treated by temozolomide and bev-acizumab. The median progression-free survival (PFS) wasabout 10months (8). Temozolomide is an imidazotetrazinederivative of the alkylating agent dacarbazine. The drug isapproved for treatment of glioblastoma multiforme andanaplastic astrocytoma (17), but is not approved for STS,whereas the use of dacarbazine is authorized for advancedSTS cases in several European UnionMember States, includ-ed Italy.We report hereafter on the activity of dacarbazine as a

single agent in a series of 8 patients with advanced, pro-gressive SFT, whomwe treated as from January 2012. Giventhe evidence of responses, we carried out preclinical experi-ments on a human high-grade DSFT xenotransplanted intoSCID mice, exploring the activity of dacarbazine, temozo-lomide, sunitinib, pazopanib, and bevacizumab.

Materials and MethodsPatientsFrom January to December 2012, we treated 8 patients

carrying a locally advanced/metastatic SFT at FondazioneIRCCS Istituto Nazionale Tumori, Milan, Italy (INT) withdacarbazine as single agent.Patient characteristics are listed in Table 1 (male/female:

3/5; mean age: 61 years; pretreatment with �1 medicaltreatment: 8; ECOG PS�3: 1). All patients had evidence ofprogressive disease (PD) before starting treatment, EasternCooperative Oncology Group performance status (ECOGPS)�3 and an adequate bone marrow and organ function.Histologic diagnosis was centrally reviewed in all cases.

The diagnosis was rendered according to the last WorldHealth Organization classification (1).

O6-methylguanine-DNA-methyltransferase gene methyla-tion assessment. O6-methylguanine-DNA-methyltransfer-ase (MGMT) gene methylation assessment was retrospec-tively conducted in all patients treated with dacarbazine.DNA was extracted from formalin-fixed paraffin-embed-ded selected tumor samples using the QIAmp DNA MiniKit (Qiagene) and bisulphate treated (Methylation KIT-Zymo Research). PCR amplification was conducted usingthe following primers: MGMT Met Fw: 50-cgaatatactaaaa-caacccgcg-30; MGMT Met Rev: 50-gtattttttcgggagcgaggc-30.MGMT UnMet Fw: 50-ccaaatatactaaaacaacccaca-30; MGMTUnMetRev: 50-tgtatttttttgggagtgaggt-30 (18). The analysiswasconducted twice in all cases.

Treatment. All patients provided a written informedconsent to the treatment. Patients received dacarbazine assingle agent, at the total dose of 1,200 mg/m2 per cycle,divided in 2 doses on day 1 and 2, infused intravenouslyover 60 minutes and repeated every 3 weeks, till toxicityor progression. In all cases, chemotherapy was adminis-tered together with steroids (dexamethasone) and anti-emetic (metoclopramide and ondansetron). Cycles werenot started unless the granulocyte count was >1,000/mLand platelets were >100,000/mL. If counts were not atthese levels, the treatment was postponed for a week. Ifgrades (G) 3 to 4 (defined according to the NationalCancer Institute Common Toxicity Criteria, version 3.0)thrombocytopenia, G4 neutropenia, or febrile neutrope-nia occurred, the dose of dacarbazine was reduced to1,000 and then to 800 mg/m2. Granulocyte colony stim-ulating factors (GCSF) were administered in case of grade3–4 neutropenia.

Clinical assessment. Full blood cell count and biochem-istry were assessed at baseline and before every administra-tion. Adverse events were recorded. Disease status wasassessed at baseline by awhole body computed tomographyscan (CT), aCT ormagnetic resonance imaging (MRI) of thesites of disease, and a whole body bone scan. CT/MRI wererepeated after 4 to 8 weeks of treatment then every 2 to 3months.

Response to treatment was assessed applying RECIST(16).

PFS and overall survival were estimated with Kaplan–Meyer method (19). Failure for PFS was progressive diseaseaccording to RECIST or death.

Experimental model and pharmacologic studiesA SFT sample suitable for mouse implantation was

obtained from the local recurrence of a patient previouslysurgically resected for a MSFT of the pelvis. The recurrenceoccurred 4 years after the primary tumor andwas consistentwith DSFT (Supplementary Fig. S1).

A fresh tumor specimen was collected at the time of thelocal relapse surgical resection, aseptically dissected, cutinto small fragments (3 � 3 � 3 mm) and grafted subcu-taneously into the right flankof 6 to8week-old female SCIDmice (Charles River, Calco, Como). Twenty-four hours afterinoculum, 100 mL of Matrigel Basement Matrix (BD Bio-sciences) were injected intratumorally. Mice were housed in

Translational RelevanceThis study is the first report showing that dacarbazine

as single agent has antitumor activity in patients withprogressive pretreated advanced solitary fibrous tumor(SFT). The clinical evidence is supported by preclinicalresults obtained on a human high-grade dedifferen-tiated-SFT xenotransplanted into severe combinedimmunodeficient (SCID) mice. When singly adminis-tered in the mouse model, the 2 triazene compoundsdacarbazine and temozolomide were found to have ahigh and superimposable antitumor activity and toinduce an almost complete tumor volume inhibition,which was maintained after treatment interruptionand confirmed pathologically. In contrast, the antian-giogenic agents sunitinib, pazopanib, and bevacizumabwere found to be less active, with tumor regrowth appre-ciable immediately after drug withdrawal. Clinical pro-spective studies are needed to compare dacarbazine andtemozolomide in patients with advanced SFT and tocorrelate their activity with tumor aggressiveness.

Dacarbazine in Solitary Fibrous Tumor

www.aacrjournals.org Clin Cancer Res; 19(18) September 15, 2013 5193




Tab

le1.

Patientsch

arac

teris

tics

Patient

IDGen

der

Ageat

timeof

CT(y)

PS

Siteof

primary

tumor

Siteofrelapse

atthetimeof

chem

otherap

ywithDTIC

Diagno

sis

Ki-67

express

ion

MGMT

Priortrea

tmen

t(res

pons

ey/n)

a

Res

pons

eto

dac

arbaz

ine:

RECIST

evalua

tion

PFS

1F

741

Pleura

Loca

llyad

vanc

edMSFT

Mod

erate

Not m

ethy

lated

Sun

itinib(y);ge

mcitabine(n)

PR

7

2F

661

Perito

neum

Abdom

enMSFT

Mod

erate

Not m

ethy

lated

Sun

itinib(n);

cyclop

hosfam

ide(n)

SD

6

3M

690

Pelvis

Live

r,perito

neum

MSFT

Mod

erate

Not m

ethy

lated

Sun

itinib(y),trab

ectedin

(n)

SD

3þ

4F

690

Perito

neum

Live

rDSFT

High

Not m

ethy

lated

Dox

orub

icin

þifo

sfam

ide(n);

sunitin

ib(y);

PR

11þ

5M

591

Pleura

Loca

l,lun

gDSFT

High

Not m

ethy

lated

Dox

orub

icin(n),ifo

sfam

ide(n),

sunitin

ib(n),trab

ectedin(n)

PD

2

6M

573

Men

inge

sLo

cal,liver

DSFT

High

Not m

ethy

lated

Dox

orub

icinþifo

sfam

ide(not

evalua

ble

forresp

onse

);ge

mcitabine(n)

SD

6

7F

552

Men

inge

sLo

cal,lung

DSFT

High

Methy

lated

Dox

orub

icinþ

ifosfam

ide(n);

high

-dos

eprolon

ged

infusion

ifosfam

ide(n);

sunitin

ib(n)

PR

8þ

8F

390

Men

inge

sLo

cal,lung

DSFT

nvNot m

ethy

lated

Sun

itinib(n);trab

ectedin

(n)

SD

4þ

aY/n,y

es/no.

Stacchiotti et al.

Clin Cancer Res; 19(18) September 15, 2013 Clinical Cancer Research5194




a pathogen-free facility with food and water available adlibitum. Tumor growth was followed by biweekly measure-ment of tumor diameters with a Vernier calliper. Tumorvolume (TV) was calculated according to the formula: TV(mm3) ¼ d2 � D/2, where d and D are the shortest and thelongest diameter, respectively. After the third passage inmice, and based on growth characteristics, the tumor linewas considered established. The xenograft origin wasauthenticated through microsatellite analysis by the Amp-FISTR Identifiler PCR Amplification Kit (Applied Biosys-tems, PN4322288).Platelet-derived-growth-factor-receptor b and VEGF re-

ceptor 2 expression/activation. Platelet-derived-growth-factor-receptor b (PDGFRB) expression was assessed byimmunohistochemistry on fixedmaterial using the rabbitanti-PDGFRB antibody (Cell Signalling Technology, cat:#4564), diluted 1:100. The reaction was carried out usingthe Bench Mark Ultra automatic staining apparatus(Ventana).PDGFRB and VEGF receptor 2 (VEGFR2) activation

profile was analyzed by means of phospho-RTK arrays(ARY001, R&D Systems; ref. 14) and by immunoprecipi-tation (IP)/Western blotting (WB). For the immunopre-cipitation analysis, equal amounts (1mg) of protein lysateswere precipitated by incubation with Protein A Sepharose(Amersham Biosciences) and specific anti-PDGFRB (cat:SC 432, Santa Cruz Biotechnology, Inc.) or anti-VEGFR2(cat: #5168, Cell Signaling Technology). Western blottingwas carried out using antiphosphotyrosine antibody (05-321) to detect the activation/phosphorylation of the tworeceptors. The filters were stripped and incubated with thespecific PDGFRB (cat: SC 432, Santa Cruz Biotechnology,Inc.) and VEGFR2 (cat: #2479, Cell Signaling Technology)antibodies to evaluate the degree of expression of the tworeceptors.O6-methylguanine-DNA-methyltransferase gene methy-

lation assessment. MGMT methylation assessment wasconducted in the human tumor specimen from whichthe model was derived and in the xenograft, as describedearlier.Xenograft treatments. Treatments with the different

drugs started when xenotransplanted tumors were approx-imately 80 mm3 (early-stage tumor). Dacarbazine was alsodelivered to mice bearing late-stage tumors (approximately250mm3). Sixmice for each experimental group were used.Sunitinib (Sutent, Pfizer) and pazopanib (Votrient, GlaxoSmith-Kline) were dissolved in 0.5% carboxymethylcellu-lose anddelivered by gavage 5 days aweek for 4weeks (qd�5d/w � 4w) at the dose of 40 mg/kg and of 100 mg/kg,respectively. Bevacizumab (Avastin, Roche) was deliveredintraperitoneally twice a week for 4 weeks (q3-4d/w � 4w)at the dose of 4mg/kg. Temozolomide was delivered bygavage 3 times per week for 4 weeks (q2-3d/w � 4w) at thedose of 50 mg/kg. Dacarbazine (Sanofi-Aventis) was deliv-ered intraperitoneally using two different schedules: (i) 3times perweek for 4weeks (q2-3d/w� 4w) at the dose of 70mg/kg; (ii) every 7 days for 4 times (q7d� 4) at the dose of210 mg/kg (20, 21).

The efficacy of drug treatment was assessed in terms oftumor volume inhibition percentage (TVI%) in treatedversus control mice expressed as TVI% ¼ 100 � [(meantumor volume treated/mean tumor volume control) �100]. The toxicity of drug treatment was determined asbody weight loss and lethal toxicity. Deaths occurring intreatedmice before the death of the first controlmousewereascribed to toxic effects.

The use of patient material in xenograft and all experi-ments were approved by the Ethics Committee for AnimalExperimentation of INT, according to institutional guide-lines that are in compliancewith national and internationallaws and policies

ResultsPatients

Eight patients were treatedwith dacarbazine, all evaluablefor response. Among them, 3 are still on therapy. Mediantreatment duration was 5 (range: 2–9þ) months.

Table 1 summarizes patients characteristics.Morphologically 3 of 8 cases were classified asMSFT, 5 as

DSFT.MGMT gene methylation assessment. All patients were

evaluable for MGMT methylation. MGMT gene resultedmethylated only in one case (n.7, Table 1), whereas in theother 7 patients it was not methylated.

Toxicity. Overall treatment was well tolerated. Grade 3neutropenia was observed in 1 case and required the adm-inistration of GCSF with improvement; grade 3 thrombo-cytopenia was noted in 3 patients and required treatmentdelay. No nonhematologic G � 2 toxicity were observed.Nobody stopped his treatment for toxicity.

Response. By RECIST, the best response was partialresponse (PR) in 3/8 cases, 4/8 SD, and 1/8 PD. Responseswere confirmed at 3 months. All SD lasted more than 3months. Figure 1 shows two tumor responses to dacarba-zine. Three patients are still on treatment. Of interest, inall the 3 cases with RECIST PR, the best response wasobserved after 4 cycles or more of treatment, followinginitial tumor stabilization. RECIST PR occurred in onepatient with a MSFT and in 2 with DSFT. A symptomaticimprovement was observed in 3 of 4 cases with symptomsat baseline. In particular, in two cases with grade 3 para-neoplastic hypoglycemia requiring steroids solved andsteroids could be completely stopped after 2 weeks fromfirst dacarbazine administration. In a third patient grade 2dyspnea fully recovered in 2 weeks.

The median PFS was 7 (range 2–12) months. All patientsare alive at the time of the present analysis.

Experimental model and pharmacologic studiesComparison of human and xenograft tumor findings. As

shown in Supplementary data and Supplementary Fig. S1,at each passage the DSFT xenograft maintained a morphol-ogy comparable with the human sample. Both human andxenograft samples showed a strong expression and activa-tion of PDGFRB along with VEGFR1 activation.






MGMT gene methylation assessment. MGMT generesulted methylated both in human sample and in theDSFT xenograft.

Antitumor activity studies. In the first experiment, theantitumor activity of sunitinib, bevacizumab, and temozo-lomide, singly administered at their reported optimal doses(22,23) was tested against early-stage DSFT xenografts. Anadditional experiment was successively carried out to inves-tigate the efficacy of pazopanib against the same tumormodel. Although at a different extent, tumor growth inhi-

bition was observed during treatment with all the differentagents. The antitumor effect was maximum for temozolo-mide and less pronounced for sunitinib, pazopanib, andbevacizumab (Fig. 2, Table 2). Tumor growth was promptlyresumed following sunitinib, pazopanib, and bevacizumabwithdrawal. In the case of sunitinib, treatment reiterationwas able to stabilize tumor volume for the duration oftreatment but tumor restarted to growth after drug with-drawal (Fig. 2). Conversely, following temozolomide tre-atment, a stabilization of tumor volume was observed

A

B

C

Figure 1. Response to dacarbazine.CT scan (arterial phase aftercontrast medium). A shows amarked hepatomegaly due tomultiple liver metastases frompelvic SFT at baseline. Adimensional response to treatmentafter 2 cycles of dacarbazine withdisappearance of some lesions isshown in B. Tumor response andhepatomegaly improved further asconfirmed by the CT scan after 8cycles of therapy (C).

Figure 2. A, efficacy of oral temozolomide (50 mg/kg, q2-3d/w � 4w), intraperitoneal bevacizumab (4 mg/kg, q3-4d/w � 4w) alone and in combination, andoral sunitinib (40 mg/kg, qdx5d/w � 4w) against SFT xenotransplanted in SCID mice. The treatment duration is indicated by the gray bar. B, efficacy of oralpazopanib (100 mg/kg, qdx5d/w � 4w) against SFT xenotransplanted in SCID mice. The treatment duration is indicated by the gray bar.

Stacchiotti et al.





without any evidence of tumor regrowth until 120 day fromdrug withdrawal (Fig. 2). No therapeutic advantage wasobserved when mice were treated with temozolomide incombination with bevacizumab (Fig. 1). No sign of toxicitywas registered following treatmentwith the different agents.A remarkable and superimposable tumor growth inhibition(maximum TVI%: about 95 for both agents) was observedtreating two groups of early-stage DSFT xenografts withtemozolomide and with dacarbazine, at their reportedoptimal doses (refs. 22, 23; Fig. 3A, Table 2). No evidenceof tumor regrowthwas appreciable 100 days after the end oftreatments.

Also in late-stage tumors, the administration of 70mg/kgdacarbazine with the q2-3d/w � 4w schedule produced aremarkable tumor growth inhibition (maximum TVI%:82), followed by stabilization of tumor volume after drugwithdrawal (Fig. 3B, Table 2), without any sign of toxicity.

In late-stage tumors, we also evaluated the antitumoractivity of 210 mg/kg dacarbazine with the q7d � 4schedule to rule out whether a more intensive schedule

Table 2. Antitumor activity of Bevacizumab,Sunitinib, Temozolomide, Dacarbazine onDSFTxenograft

DrugDose(mg/kg) Schedule Route

MaxTVI%1

(day)

Early-stageBevacizumab 4 q3-4d/w � 4w i.p. 78 (108)Sunitinib 40 qd � 5d/w � 4w p.o. 52 (115)Pazopanib 100 qd � 5d/w � 4w p.o. 41 (60)Temozolomide 50 q2-3d/w � 4w p.o. 96 (120)Dacarbazine 70 q2-3d/w � 4w i.p. 95 (120)

Late stageDacarbazine 70 q2-3d/w � 4w i.p. 82 (105)Dacarbazine 210 q7d � 4 i.p. 89 (105)

Abbreviation: p.o., per os.1Maximum tumor volume inhibition % in treated versus con-trol mice. In parentheses, the day on which it was assessed.

Figure 3. A, efficacy of oraltemozolomide (50 mg/kg, q2-3d/w� 4w) and intraperitonealdacarbazine (70 mg/kg, q2-3d/w�4w) against SFT growing in SCIDmice. The treatment duration isindicated by the gray bar. B,efficacy of intraperitonealdacarbazine against SFTxenotransplanted in SCID miceaccording to two differentschedule: (70 mg/kg, q2-3d/w �4w) or (210 mg/kg, q7d � 4). Thetreatment duration is indicated bythe gray bar.






would have corresponded to a superior activity. In fact, inthe clinical practice dacarbazine is usually administeredevery 3 weeks, whereas temozolomide is given daily. Aslight increase in tumor growth inhibition (maximumTVI%: 89) was observed compared with the previousschedule (Fig. 3B, Table 2). However, treatment induced15% body weight loss and one toxic death.

Pathologic evaluation of drug-treated early- and late-stagexenografts. Early-stage DSFT xenografts were sacrificed120 day after the end of the treatments with sunitinib,bevacizumab, temozolomide, and dacarbazine. Mice trea-ted with pazopanib were instead sacrificed soon after theend of treatment. In line with themacroscopic features (i.e.,no evidence of tumor regrowth), post-temozolomide (Fig.4, C) and post-dacarbazine (Fig. 4, D) tumor samples sho-wed a marked cellular depletion. Conversely, no changescomparedwith baselinewere observed in the post-sunitinib(Supplementary data and Supplementary Fig. S2C), post-bevacizumab (Supplementary data and Supplementary FigSD), and post-pazopanib (Supplementary data and Sup-plementary Fig. S2E) tumor specimens. This was consistentwith the macroscopic evidence of progression in the post-sunitinib and in the post-bevacizumab xenografts. Similarlyto what observed in early-stage tumors, a marked cellulardepletion was found after dacarbazine treatment also inlate-stage xenografts, irrespectively from treatment sche-dules (data not shown).

PDGFRB and VEGFR2 expression/activation. After fivedays of treatment, sunitinib, and pazopanib induced adecrease inPDGFRBactivation, bevacizumabandpazopanibin VEGFR2 (Supplementary Fig. S3). These results are in linewith tumor growth curves shown in Fig. 2.

Contrary to what was observed in mice treated with sun-itinib andbevacizumab, the tumor regrowthwasobserved inxenografts treated with pazopanib, whereas they were stillunder treatment (Fig. 2). Therefore, we decided to evaluatePDGFRB and VEGFR2 status also at the end of treatmentwith pazopanib, for example, after four weeks of adminis-tration. Of interest, VEGFR2 was phosphorylated (Supple-mentary Fig. S3).

The unexpected VEGFR2 reactivation could represent amechanism of resistance. Additional "in vivo" studies areongoing to better understand the mechanisms underlyingresponse and resistance to antiangiogenics in SFT.

DiscussionIn this retrospective case series analysis, 8 patients with a

progressive pretreated advanced SFT (3MSFT, 5DSFT) weretreated with dacarbazine. We observed 3 PR, 4 SD (alllasting more than 3 months), and 1 PD, with a medianPFS of 7 months. Then, we studied the antitumor effect ofdacarbazine using an in vivo model of DSFT. To put this inthe context of other promising agents in SFT, we alsoanalyzed the effect of sunitinib, pazopanib, bevacizumab,and temozolomide as single agents, and bevacizumab incombination with temozolomide on the DSFT xenograft.All agentswere shown tobe active.However, temozolomideand dacarbazine were superior in terms of tumor shrinkage,time to progression after treatment interruption and path-ologic response. Overall, temozolomide and dacarbazineshowed a cytotoxic effect, whereas sunitinib, pazopanib,and bevacizumab displayed a cytostatic role. In addition,dacarbazine activity was equivalent with a more or lessfrequent administration schedule.

Figure 4. SFT xenotransplanted inSCID mice pathologic evaluationbefore and after treatment. A andB, pretreatment samples: high-grade sarcoma aspects mixed withcartilaginous (A) and osseouscomponent (B). C and D, post-temozolomide and post-dacarbazine samples: 120 daysafter the end of treatment withtemozolomide (C) and dacarbazine(D) tumor lesions were removed.The samples showed an almostcomplete response to treatment,with almost no more evidence oftumor cells (C and D).

Stacchiotti et al.





SFT represents an exceedingly rare disease. In addition,many cases are "typical", that is low-risk, whereas those witha higher metastatic potential are "malignant" or "dediffer-entiated/pleomorphic", thus breaking down further clinicalseries (1). No prospective studies focusing on chemotherapyare available. Responses to sunitinib (9–13), and bevacizu-mab in combination to temozolomide were reported (8),whereas no clinical nor preclinical data on temozolomideand bevacizumab as single agents are available. Thus, weretrospectively reviewed a small series of SFT patients whoreceived single-agent dacarbazine at our institute and weevaluated the role of all those agents in a xenograft model ofDSFT. Dacarbazine is a triazene compound as temozolo-mide (24) and unlike temozolomide it is approved inEurope for the medical therapy for advanced STS. This isthe reasonwhywe could not treat a second group of patientswith temozolomide. However, for the first time these datashow that dacarbazine can be a well-tolerated therapeuticoption in strongly pretreated advanced SFT patients.Our preclinical results support clinical evidence. A lim-

itation of our in vivo experiments is due to the intrinsicxenograft model characteristics, which specifically recapit-ulate the features of DSFT. In fact, SFT is a disease char-acterized by a broad spectrum of malignancy (1, 25–27)and DFST represent a particular subset among differentSFT subtypes, though it is probably more frequent thanbelieved in advanced SFT series. Thus, our preclinicalfindings need to be confirmed in so-called, less aggressive"malignant" SFT. Another limitation is due to the fact thatour data refer only to one model of DSFT. In principle, thiscan be not representative of all cases of dedifferentiatedsolitary fibrous tumor. However, due to the difficulty togenerate mouse models from such a rare and slowlygrowing sarcoma we could not implement the xenograftpanel. As matter of fact, work is in progress in our labo-ratory to establish new SFT models for future studies. Withthese limitations, in our DSFT in vivomodel, we confirmedthat sunitinib, pazopanib, bevacizumab, temozolomide,and dacarbazine as single agents are all active, though to adifferent extent. Of interest, we found that temozolomideand dacarbazine were superior in terms of tumor shrink-age, as shown by a maximum TVI of about 95% for bothagents. Furthermore, temozolomide and dacarbazine anti-tumor effects lasted even after long treatment interrup-tions (i.e., no tumor progression observed at 120 day fromtreatment completion), whereas tumor regrowth wasobserved soon after withdrawing sunitinib and bevacizu-mab. In case of pazopanib, tumor started regrowing ear-lier, when mice were still under therapy. This was con-firmed by the pathologic evaluation of xenografts obtainedwhen animals were sacrificed: 120 days after treatmentinterruption tumors treated with temozolomide and dac-arbazine showed an almost complete pathologic response,whereas tumors treated with sunitinib, bevacizumab, andpazopanib were completely viable.These data are consistent with a cytotoxic effect of temo-

zolomide and dacarbazine, compared with a cytostaticeffects of antiangiogenics. As expected, temozolomide and

dacarbazine were superimposable both in terms of tumorregression, treatment effect duration and pathologic res-ponse. Of note, dacarbazine is a prodrug that requiresenzymatic conversion to its active form, 5-(3-methyltria-zen-1yl)-imidazole-4-carboxamide (MTIC), whereas temo-zolomide is rapidlymetabolized toMTICat physiologic pH,without enzymatic involvement. This may not entail anydifference in mice, as it is expected that dacarbazine con-version occurs better in mice than in humans (28). Thus,in principle, temozolomide might be advantageous inhumans, though clinical evidence thereof is lacking. Inaddition, temozolomide could be superior to dacarbazinein case of central nervous system disease, whether for brainmetastases or meningeal primaries (which is typical of asubgroup of SFT) given its ability to enter the cerebrospinalfluid (29). As a matter of fact, we saw convincing responsesto dacarbazine in a small group of patients. A comparativestudy would be useful to confirm dacarbazine activityin a larger number of patients and to compare it withtemozolomide.

Of notice,MGMT genewas shown to bemethylated bothin theDSTF xenograft and in the human tumor fromwhichit was derived, whereas it was methylated only in one caseamong patients we treated with dacarbazine. In particularMGMT was methylated in one of the 3 cases who respon-ded to dacarbazine. On this basis, a correlation betweenthe antitumor activity of dacarbazine and MGMT statuscannot be excluded. In fact, it is known that in glioblasto-ma the presence of MGMT promoter methylation-–thatenhances the response to alkylating agents by inhibitingDNA repair—is predictive of a better response to temozo-lomide in combination with radiotherapy (17). On thecontrary, MGMT predictive role has not been definitivelyconfirmed in other tumors responsive to temozolomidesuch as melanoma (30). The correlation between MGMTgene methylation status and the response to dacarbazineand temozolomide can thus represent an interesting fieldof research in SFT.

We found that the temozolomide–bevacizumab combi-nation did not induce a better therapeutic activity thantemozolomide alone. A tentative explanation could be thatthe administration of antiangiogenic drugs may impaircytotoxic agent delivery by pruning tumor vessels and byreducing vascular permeability. Again, a comparative studyon temozolomide or dacarbazine as single agents versustheir combination with an antiangiogenic agent would beworth doing in principle.

In clinical practice, temozolomide is administered everyday, whereas dacarbazine is given every 3 weeks. For thisreason, we decided to run an additional experiment com-paring two different dacarbazine schedules: dacarbazineat a lower dose every 3 days versus dacarbazine at a higherdose every 7 days, for an overall equivalent dose. Of inter-est, no remarkable difference could be noted in activitybetween the two regimens.

Using dacarbazine, we could observe dimensional re-sponses in some patients, and tumor disease stabilizationin others, both in MSFT and in DSFT. Responses were






prolonged and corresponded to a significant improvementin symptomatic cases. In particular, we could note the rapidresolution of a hypoglycemic crisis in 2 patients with abaseline paraneoplastic grade 3–4 hypoglicemia requiringsteroids. As expected, dacarbazine was very well tolerated.

We had already published a retrospective study on theactivity of sunitinib in a series of 30 patients with advanc-ed SFT. After sunitinib, we observed 2 RECIST PR and 16SD, with a median PFS of 6 months and a greater efficacyof sunitinib in MSFT compared with DSFT (12). With thelimitation of an external comparison among small retro-spective series, it can be noted that the RR by RECISTwas greater among patients treated with dacarbazine, forexample, 3 of 8 cases, compared with what obtained withsunitinib. This suggests that dacarbazine could be moreeffective in achieving a tumor shrinkage compared withsunitinib, at least in more aggressive cases. Interestingly,most patients treated in this series received sunitinibbefore dacarbazine (Table 1): responses to dacarbazinewere observed in patients who progressed under sunitiniband vice versa.

In conclusion, our results confirm that temozolomideand dacarbazine can be active as single agents in SFT. Aprospective phase II study on dacarbazine in advancedSFT is due to start. Among others, subjects to be eluci-dated could include a comparison between dacarbazineand temozolomide, the correlation of their antitumoractivity with tumor aggressiveness (i.e., with whether the

SFT is malignant or dedifferentiated), the value ofMGMTgene methylation.

Disclosure of Potential Conflicts of InterestS. Stacchiotti has commercial research grant from Pfizer and Glaxo Smith

Kline. P.G. Casali is a consultant/advisory board member in Pfizer. Nopotential conflicts of interest were disclosed by the other authors.

Authors' ContributionsConception and design: S. Stacchiotti, T. Negri, N. Zaffaroni, P.G. CasaliDevelopment of methodology: S. Stacchiotti, E. Tamborini, S. PilottiAcquisitionofdata (provided animals, acquired andmanagedpatients,provided facilities, etc.): S. Stacchiotti, M. Tortoreto, F. Bozzi, A. Messina,M. Libertini, E. Palassini, D. Cominetti, A. GronchiAnalysis and interpretation of data (e.g., statistical analysis, biosta-tistics, computational analysis): S. Stacchiotti, M. Tortoreto, F. Bozzi, E.Tamborini, A. Messina, D. Cominetti, A. Gronchi, N. Zaffaroni, P.G. CasaliWriting, review, and/or revision of the manuscript: S. Stacchiotti, E.Tamborini, C. Morosi, T. Negri, A. Gronchi, S. Pilotti, N. Zaffaroni, P.G.CasaliAdministrative, technical, or material support (i.e., reporting or orga-nizing data, constructing databases): S. Stacchiotti, C. Morosi, M.LibertiniStudy supervision: S. Stacchiotti

Grant SupportThis work was supported by grant from Associazione Italiana per la

Ricerca sul Cancro (AIRC): IG 10300.The costs of publication of this article were defrayed in part by the

payment of page charges. This article must therefore be hereby markedadvertisement in accordance with 18 U.S.C. Section 1734 solely to indicatethis fact.

Received March 22, 2013; revised June 30, 2013; accepted July 9, 2013;published OnlineFirst July 25, 2013.

References1. Fletcher CDM, et al., editors. World Health Organization (WHO) clas-

sification of tumours of soft tissue and bone. Pathology and Genetics.Lyon: IARC Press; 2013.

2. Robinson DR,Wu YM, Kalyana-SundaramS, Cao X, Lonigro RJ, SungYS, et al. Identification of recurrent NAB2-STAT6 gene fusions insolitary fibrous tumor by integrative sequencing. Nat Genet 2013;45:180–5.

3. Chamberlain MC, Glantz MJ. Sequential salvage chemotherapy forrecurrent intracranial hemangiopericytoma. Neurosurgery 2008;63:720–6.

4. Galanis E, Buckner JC, Scheithauer BW, Kimmel DW, Schomberg PJ,Piepgras DG. Management of recurrent meningeal hemangiopericy-toma. Cancer 1998;82:1915–20.

5. Ferigo N, Cottalorda J, Allard D, Gentil-Perret A, Fessy M, Berger C,et al. Successful treatment via chemotherapy and surgical resection ofa femoral hemangiopericytoma with pulmonary metastasis. J PediatrHematol Oncol 2006;28:237–40.

6. Beadle GF, Hillcoat BLJ. Treatment of advanced malignant heman-giopericytoma with combination adriamycin and DTIC: a report of fourcases. Surg Oncol 1983;22:167–70.

7. Stacchiotti S, Libertini M, Negri T, Palassini E, Gronchi A, Fatigoni S,et al. Response to chemotherapy of solitary fibrous tumor: a retro-spective study. Eur J Cancer 2013; 49:2376–83.

8. Park MS, Patel SR, Ludwig JA, Trent JC, Conrad CA, Lazar AJ, et al.Activity of temozolomide and bevacizumab in the treatment of locallyadvanced, recurrent, and metastatic hemangiopericytoma and malig-nant solitary fibrous tumor. Cancer. 2011;117:4939–47.

9. Mulamalla K, Truskinovsky AM, Dudek AZ. Rare case of hemangio-pericytoma responds to sunitinib. Transl Res 2008;151:129–33.

10. George S, Merriam P, Maki RG, Van den Abbeele AD, Yap JT, AkhurstT, et al. Multicenter phase II trial of sunitinib in the treatment of non-

gastrointestinal stromal tumor sarcomas. J Clin Oncol 2009;27:3154–60.

11. Domont J, Massard C, Lassau N, Armand JP, Le Cesne A, Soria JC.Hemangiopericytoma and antiangiogenic therapy: clinical benefit ofantiangiogenic therapy (sorafenib and sunitinib) in relapsed malignanthaemangioperyctoma/solitary fibrous tumour. InvestNewDrugs2010;28:199–202.

12. Stacchiotti S, Negri T, Libertini M, Palassini E, Marrari A, De Troia B,et al. Sunitinib in solitary fibrous tumor. Ann Oncol 2012;23:3171–9.

13. Sleijfer S, Ray-Coquard I, Papai Z, Le Cesne A, Scurr M, Sch€offski P,et al. Pazopanib, a multikinase angiogenesis inhibitor, in patients withrelapsed or refractory advanced soft tissue sarcoma: a phase II studyfrom the European organisation for research and treatment of cancer-soft tissue and bone sarcoma group (EORTC study 62043). J ClinOncol 2009;27:3126–32.

14. Stacchiotti S, Negri T, Palassini E, Conca E, Gronchi A, Morosi C, et al.Sunitinib malate and figitumumab in solitary fibrous tumor: patternsand molecular bases of tumor response. Mol Cancer Ther 2010;9:1286–97.

15. Quek R, Wang Q, Morgan JA, Shapiro GI, Butrynski JE, Ramaiya N,et al. Combination mTOR and IGF-1R inhibition: phase I trial of ever-olimus and figitumumab inpatientswith advanced sarcomas andothersolid tumors. Clin Cancer Res 2011;17:871–9.

16. Therasse P, Arbuck SG, Eisenhauer EA, Wanders J, Kaplan RS,Rubinstein L, et al. New guidelines to evaluate the response totreatment in solid tumors. European Organization for Research andTreatment of Cancer Institute of the United States, National CancerInstitute of Canada. J Natl Cancer Inst 2000;92:205–6.

17. Thomas RP, Recht L, Nagpal S. Advances in the management ofglioblastoma: the role of temozolomide and MGMT testing. ClinPharmacol 2013;5:1–9.

Stacchiotti et al.





18. Herman JG, Graff JR,Myohanen S, Nelkin BD, Baylin SB.Methylation-specific PCR: a novel PCR assay for methlation status of CpG islands.Prc Natl Acad Sci U S A 1996;93:9821–6.

19. Kaplan WE, Meier P. Nonparametric estimation from incompleteobservations. J Am Stat Assoc 1958;53:457–81.

20. Najar HM, Dutz JP. Topical CpG enhances the response of murinemalignant melanoma to dacarbazine. J Invest Dermatol 2008;128:2204–10.

21. Engesæter B, Engebraaten O, Flørenes VA, Mælandsmo GM. Dacar-bazine and the agonistic TRAIL receptor-2 antibody lexatumumabinduce synergistic anticancer effects in melanoma. PLoSONE 2012;7:e45492.

22. Cassinelli G, Zuco V, Petrangolini G, De Cesare M, Tortoreto M, LanziC, et al. The curative efficacy of namitecan (ST1968) in preclinicalmodels of pediatric sarcoma is associatedwith antiangiogenic effects.Biochem Pharmacol 2012;84:163–71.

23. Kitange GJ, Mladek AC, Carlson BL, Schroeder MA, Pokorny JL, CenL, et al. Inhibition of histone deacetylation potentiates the evolutionof acquired temozolomide resistance linked to MGMT upregulationin glioblastoma xenografts. Clin Cancer Res 2012;18:4070–9.

24. Stevens MF, Newlands ES. From triazines and triazenes to temozo-lomide. Eur J Cancer 1993;29:1045–7.

25. Mosquera JM, Fletcher CDM. Expanding the spectrum of malignantprogression solitary fibrous tumor – a study of 8 cases with a discreteanaplastic component – is this dedifferentiated SFT?AmJSurg Pathol2009;33:1314–21.

26. Magro G, Emmanuele C, LopesM, Vallone G, Greco P. Solitary fibroustumour of the kidney with sarcomatous overgrowth. Case report andreview of the literature. APMIS 2008;116:1020–5.

27. Collini P, Negri T, Barisella M, Stacchiotti S, Palassini E, Pastorino U,et al. High-grade sarcomatous overgrowth in solitary fibrous tumor:a clinico-pathological study of 10 cases. Am J Surg Path 2012;36:1202–15.

28. Samulitis BK, Dorr RT, Chow HH. Interaction of dacarbazine andimexon, in vitro and in vivo, in humanA375melanoma cells. AnticancerRes 2011;31:2781–5.

29. Ostermann S, Csajka C, Buclin T, Leyvraz S, Lejeune F, Decosterd LA,et al. Plasma and cerebrospinal fluid population pharmacokinetics oftemozolomide in malignant glioma patients. Clin Cancer Res 2004;10:3728–36.

30. Hassel JC, Sucker A, Edler L, Kurzen H, Moll I, Stresemann C, et al.Methylation correlates with tolerance of temozolomide treatmentin melanoma but not with clinical outcome. Br J Cancer 2010;103:820–6.






2013;19:5192-5201. Published OnlineFirst July 25, 2013.Clin Cancer Res S. Stacchiotti, M. Tortoreto, F. Bozzi, et al. Preclinical Evidence vis-à-vis Temozolomide and AntiangiogenicsDacarbazine in Solitary Fibrous Tumor: A Case Series Analysis and

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