Clofarabine, Cyclophosphamide and Etoposide As Single-Course Re-Induction Therapy for Children with Refractory/Multiple Relapsed Acute Lymphoblastic Leukaemia

research paper

Clofarabine, cyclophosphamide and etoposide as single-course re-induction therapy for children with refractory/multiple relapsed acute lymphoblastic leukaemia

Franco Locatelli,1 Anna M. Testi,2 Maria Summary Ester Bernardo,1 Carmelo Rizzari,3 Alice Bertaina,1 Pietro Merli,1 Andrea The safety and efﬁcacy of the combination clofarabine/cyclophosphamide/ Pession,4 Eugenia Giraldi,5 Rosanna etoposide were evaluated in children with advanced acute lymphoblastic Parasole,6 Walter Barberi2 and Marco leukaemia (ALL). The study enrolled 25 paediatric patients (median age Zecca1 12Æ5 years) with either refractory (n = 17; 68%) or multiple relapsed (n =8; 1Oncoematologia Pediatrica, Fondazione IRCCS 32%) ALL to receive clofarabine 40 mg/m2, cyclophosphamide 400 mg/m2 Policlinico San Matteo, Universita` di Pavia, and etoposide 150 mg/m2, daily for 5 consecutive days. No patient died from 2Cattedra di Ematologia, Universita` La Sapienza, treatment-related complications. The most common adverse events were 3 Roma, Clinica Pediatrica Universita` di Milano febrile neutropenia, mucositis and reversible liver toxicity; no case of liver 4 Bicocca, Monza, Clinica Pediatrica, Ospedale S. veno-occlusive disease was reported. The overall remission rate was 56%: 13 ` Orsola, Universita di Bologna, Bologna, patients (52%) achieved complete remission (CR) and one (4%) CR without 5Divisione di Pediatria, Ospedali Riuniti, platelet recovery (CRp). In seven of the 13 (54%) patients achieving CR, Bergamo, and 6Oncoematologia Pediatrica, remissions were of sufﬁcient duration to allow patients to receive allogeneic Ospedale Santobono-Pausilipon, Napoli, Italy haematopoietic stem cell transplantation. The probability of CR/CRp was greater in the 17 patients with B cell precursor ALL than in the eight with T-ALL (76% vs. 12%, respectively, P <0Æ01). The 18-month overall survival probability was 39% and 0% in patients who did or did not respond to the treatment, respectively (P <0Æ01). These data suggest that the clofarabine/ Received 21 June 2009; accepted for publication cyclophosphamide/etoposide regimen is well tolerated and can induce 5 August 2009 clinical response in a relevant proportion of children with refractory/ Correspondence: Professor Franco Locatelli, multiple relapsed ALL. Oncoematologia Pediatrica, Fondazione IRCCS Policlinico San Matteo, Universita` di Pavia, P.le Keywords: acute lymphoblastic leukaemia, childhood haematological malig- Golgi, 2, I-27100 Pavia, Italy. nancies, refractory/relapsed disease, clofarabine, combination therapy, allo- E-mail: [email protected] geneic haematopoietic stem cell transplantation.

The proportion of children with acute lymphoblastic leukae- particular, for children with isolated bone marrow (BM) mia (ALL) successfully cured with chemotherapy has progres- relapse occurring after a short duration of ﬁrst remission, and sively increased over time (Pui & Evans, 2006). It is estimated for those with T-cell ALL, the probability of 5-year leukaemia- that the use of modern combination chemotherapy results in free survival does not exceed 30%, even when they receive long-term remission in nearly 80% of children diagnosed with allogeneic haematopoietic stem cell transplantation (HSCT) ALL (Conter et al, 1997, 2000; Pession et al, 2005; Moghrabi (Henze et al, 1991; Einsiedel et al, 2005; Paganin et al, 2008). et al, 2007; Moricke et al, 2008). Despite these advances, In published studies, the most frequent cause of failure for approximately 20% of children with ALL experience leukaemia children with relapsed ALL is resistance to second-line therapy, relapse, which remains the leading cause of treatment failure or subsequent BM relapse (Henze et al, 1991; Chessells et al, (Pui & Evans, 2006). While a substantial proportion of 2003; Rizzari et al, 2004; Einsiedel et al, 2005; Paganin et al, children with relapsed ALL achieve a second remission, the 2008). In light of the very poor prognosis of these patients ﬁnal outcome of paediatric patients who experience leukaemia when treated with conventional second-line therapies, recurrence remains unsatisfactory (Henze et al, 1991; Chessells innovative treatment strategies based on the use of novel et al, 2003; Rizzari et al, 2004; Paganin et al, 2008). In anti-leukaemia agents are needed.

First published online 31 August 2009 ª 2009 Blackwell Publishing Ltd, British Journal of Haematology, 147, 371–378 doi:10.1111/j.1365-2141.2009.07882.x F. Locatelli et al

Antimetabolites are some of the most effective drugs against before treatment. This study was conducted according to haematological malignancies. In particular, fludarabine and guidelines active in each institution participating in the trial cladribine are active in the treatment of relapsed acute and in accordance with the principles of the Helsinki leukaemias, although their use is associated with important Declaration. non-haematological toxicity (Estey et al, 1994; Krance et al, 2001; Gandhi et al, 2001; Plunkett & Gandhi, 2001), especially Treatment plan dose-limiting neurotoxicity (Spriggs et al, 1986; Warrell & Berman, 1986). Clofarabine (2-chloro-2¢-fluoro-2¢-deoxy-9-b- Clofarabine was administered intravenously at a dosage of d-arabinofuranosyladenine) is a second-generation purine 40 mg/m2 over 2 h daily, while cyclophosphamide was given nucleoside analogue synthesized with the aim of overcoming at a dosage of 400 mg/m2 in 1 h and etoposide was infused at the limitations, in terms of both efficacy and non-haemato- a dosage of 150 mg/m2 in 2 h. Clofarabine was administered logical toxicity, of fludarabine and cladribine, while maintaining before each dose of cyclophosphamide and etoposide. All their best qualities (Kantarjian et al, 2007). drugs were administered for 5 consecutive days. Dose Phase I and II studies aimed at addressing the safety and calculation was based on body-surface area obtained from efficacy of single-agent clofarabine have been conducted in height and actual weight. Prophylactic steroids were given to both adults and paediatric patients (Kantarjian et al, 2003; Jeha prevent cytokine release syndrome in patients with more than et al, 2004, 2006). These studies have demonstrated that 30 · 109 blast cells/l in peripheral blood at time of treatment. clofarabine is active in different subtypes of resistant/multiple No patient had active central nervous system (CNS) disease at relapsed leukaemia, leading to overall remission (OR) in about time of treatment as shown by diagnostic lumbar puncture. In 20% of paediatric patients, without inducing the typical view of this finding and of the possible, unknown interaction neurotoxicity of first-generation nucleoside analogues. In view of the triple combination with intrathecal chemotherapy, of the results obtained in these studies, clofarabine has been none of the patients received CNS prophylaxis. Responding approved as single agent for the treatment of paediatric patients were given allogeneic HSCT if a suitable donor was patients aged 1–21 years with ALL failing at least two prior immediately available or were given consolidation courses of regimens by both the Federal Drug Agency in the United States chemotherapy including multiple agents active against ALL and the European Medicinal Evaluation Agency in Europe. cells, chosen according to the treating physician’s preference. As clofarabine inhibits DNA polymerases, ribonucleotide Two out of the 25 patients were given a second course of reductase and DNA repair, there is a rationale for considering clofarabine, cyclophosphamide and etoposide as consolidation the combination of this drug with agents able to damage DNA, therapy. such as cyclophosphamide and etoposide (Yamauchi et al, 2001). Recently, Hijiya et al (2007) reported encouraging, Response criteria although preliminary data, on a phase I dose-escalating trial investigating the safety of different doses of clofarabine Response to treatment was assessed using morphological, combined with cyclophosphamide and etoposide for treatment cytogenetic and immunophenotyping analysis. Complete remis- of refractory or relapsed ALL. sion (CR) was defined as the following: absence of physical signs This report describes the results of a multicentre study of leukaemia or detectable leukaemia cells on peripheral blood carried out in paediatric patients with either multiple relapsed smears; BM with active haematopoiesis and <5% leukaemia or refractory ALL who received a single course of clofarabine cells; an absolute granulocyte count >1 · 109/l, and a platelet therapy combined with cyclophosphamide and etoposide with count >100 · 109/l; and normal cerebrospinal fluid. A CRp was the aim of re-inducing remission. defined as the presence of all the criteria required for CR with the exception of a platelet count >100 · 109/l. The OR rate was defined as the number of patients who achieved CR or CRp Patients and methods divided by the number of treated patients. Partial response (PR) was defined as 5% to 25% marrow blasts, an absolute granu- Study group locyte count >0Æ5 · 109/l, and a platelet count >25 · 109/l. The Patients aged 15 years or less at time of diagnosis and 21 years National Cancer Institute (NCI) Common Toxicity Criteria or less at the time of treatment were eligible. Patients must (version 3.0) (http://ctep.cancer.gov/protocolDevelopment/ have had a performance status £2 according to Eastern electronic_applications/docs/ctcaev3.pdf) was the basis upon Cooperative Oncology Group criteria and no active infections. which all adverse events were described and graded, based on the Other eligibility criteria included: patients serum bilirubin £2· treating physician’s assessment. upper limit of normal (ULN) for age; aspartate transaminase and alanine transaminase £5· ULN; and serum creatinine <2· Patient monitoring ULN. Disease status was assessed by history, clinical evaluation, morphological, cytogenetic and immunophenotyping History and physical examination, complete blood count, analysis. Patients’ parents gave written informed consent serum chemistry and BM aspirate were performed before

372 ª 2009 Blackwell Publishing Ltd, British Journal of Haematology, 147, 371–378 Clo/CTX/VP-16 for Advanced Childhood ALL starting chemotherapy. Echocardiogram was performed before probability, with the corresponding 95% conﬁdence interval treatment and at time of haematopoietic recovery. Serum levels (CI). P values < 0Æ05 were considered signiﬁcant. of C-reactive protein, procalcitonin and galactomannan were obtained at least once a week during the aplasia period. Results

Supportive therapy Patients and treatment All patients were hospitalized for treatment. In the days Between October 2006 and August 2008, 25 patients (18 males following chemotherapy and until haematopoietic recovery, 23 and seven females) were enrolled and treated in six Italian patients remained in the in-patient ward, receiving daily paediatric centres. Their characteristics are presented in physical examination, complete blood count and serum Table I. Eight children were treated for a second (n =6)or chemistry, while two patients were managed in the outpatient third (n = 2) BM relapse, while 17 patients were resistant to unit. the last course of chemotherapy. Among these latter 17 Supportive therapy was administered according to protocols patients, six proved to be resistant to two courses of active in each institution that enrolled patients into the study. chemotherapy used to treat a first BM relapse, four were All children were given acyclovir for prevention of herpes- resistant to one course of chemotherapy used to treat a first viruses infection. Prophylactic antibiotics (ciprofloxacin or BM relapse and the remaining seven were resistant to one amoxicillin conjugated with clavulanic acid) were administered course of chemotherapy used to treat a second BM relapse. In to all children. Broad spectrum antibiotics were given if a the majority of these patients, the last treatment before patient became febrile. Voriconazole was administered for clofarabine, cyclophosphamide and etoposide was adminis- preventing fungal infections in 15 patients, starting 2 d after tered according to the Associazione Italiana di Ematologia e completion of chemotherapy until neutrophil recovery, while Oncologia Pediatrica (AIEOP) REC 2003 protocol, which is the others were given fluconazole. Antifungal therapy against based on a Berlin-Frankfu¨rt-Mu¨nster backbone (Paganin et al, both yeasts and moulds was modified if there was clinical evidence of proven/probable fungal infection (diagnosed Table I. Patient characteristics (N = 25). according to criteria previously published) (Ascioglu et al, 2002). Number of patients enrolled 25 (100%) Recombinant human granulocyte-colony stimulating factor Gender: male/female 18/7 (72%/28%) (G-CSF) was not used to accelerate neutrophil recovery, except Age at diagnosis (years) 8 (1–15) WBC at diagnosis (·109/l) 30 (1Æ1–360) in one patient. First-line protocol Cyclophosphamide-induced haemorrhagic cystitis was pre- AIEOP ALL 2000 16 (64%) vented through the use of uromitexan, which was infused at AIEOP ALL 95 6 (24%) the dose of 120% of the cyclophosphamide dose. DFCI ALL 3 (12%) Immunophenotype Statistical analysis B lineage 17 (68%) T lineage 8 (32%) The study was an open-label, multicentre, nonrandomized National Cancer Institute classification at diagnosis* phase II trial. The study objective was to estimate the OR rate. Standard risk 8 (32%) The data cut-off for this study was December 31, 2008. Patients High risk 17 (32%) were censored at time of last follow-up, while death was Cytogenetic abnormalities at diagnosis t(9;22) 2 (8%) counted as an event in the calculation of overall survival (OS). t(12;21) 2 (8%) Quantitative variables were reported as median and range. Hyperdiploid karyotype 1 (4%) Patient- and disease-related variables were analysed for their Hypodiploid karyotype 1 (4%) prognostic value on probability of obtaining CR or CRp. The Age at treatment (years) 12Æ5 (range, 4–21) following variables were tested for their potential influence on Disease status at treatment the probability of obtaining response to treatment with Second relapse 6 (24%) clofarabine, cyclophosphamide and etoposide: patient gender Third relapse 2 (8%) (male versus female), immunophenotype (BCP ALL versus T Refractory disease 17 (68%) ALL), WBC at diagnosis (values above versus those below the Previous allogeneic HSCT 7 (29%) median), previous HSCT (yes versus no), patient age at AIEOP, Associazione Italiana di Ematologia e Oncologia Pediatrica; treatment (patients younger versus those older than the median DFCI, Dana Farber Cancer Institute; HSCT, Haematopoietic Stem Cell age) and disease phase at time of treatment (patients with ALL Transplantation. in second or third BM relapse versus those with resistant/ *Patients with B cell precursor ALL were classified in standard and refractory leukaemia). The probability of OS was estimated by high risk according to the criteria reported by Smith et al (1996), while the Kaplan–Meier method, and expressed as 18-month those with T-ALL were considered at high risk.

ª 2009 Blackwell Publishing Ltd, British Journal of Haematology, 147, 371–378 373 F. Locatelli et al

2008). The median BM blast percentage in the overall Response and outcome population at time of treatment was 75% (range, 40–100%). Seventeen patients were diagnosed with BCP ALL and eight Thirteen patients (52%) achieved CR and one (4%) CRp, with T-cell ALL. Two patients had Ph+ BCP ALL; both had giving an OR rate of 56%. Two patients (8%) had PR and nine been previously treated with imatinib mesylate. Seven patients patients (36%) had completely resistant disease, resulting in a had previously received an allograft; the median time elapsing failure rate of 44%. Thirteen out of the 17 patients (76%) with from HSCT to treatment with clofarabine, cyclophosphamide BCP ALL achieved CR/CRp, while one of the eight patients and etoposide was 10 months (range, 3–42). In four out of with T-ALL (12%) responded to treatment (P <0Æ01). Of the these seven patients, total body irradiation was part of the 17 patients who were refractory to their most recent prior preparative regimen, while the remaining three patients had regimen, eight (47%) achieved either CR or CRp. By contrast, been prepared for HSCT with a busulfan-based conditioning. six out of the eight patients (75%) with multiple relapsed ALL obtained CR (not statistically different from patients with refractory/resistant ALL). Both patients with Ph+ ALL Toxicity obtained CR. Neither patient gender, WBC count at diagnosis, Treatment-related toxicities are presented in Table II. No nor age at treatment influenced the probability to respond to patient died due to treatment-related complications; more- the treatment (data not shown). Notably, four out of the seven over, no discontinuation of treatment due to adverse events patients (57%) who had previously received allogeneic HSCT was reported. In addition, no patient experienced tumour responded to the treatment, as compared to 10 out of the 18 lysis, cytokine-release syndrome, skin rash, palmar-plantar patients (56%) who had not been previously transplanted. erythrodysesthesia, or hepatic veno-occlusive disease (VOD). Seven out of the 13 patients (54%) who achieved CR Hepatic dysfunction, as evidenced by grade 3 or lower subsequently proceeded to allogeneic HSCT from either a transaminitis or hyperbilirubinemia or both, occurred in 16 human leucocyte antigen (HLA)-matched sibling (n = 2), an patients. Elevation of transaminases occurred around day 5–6 unrelated donor (n = 3), or an HLA-partially matched family, (range, day 3–10) from the beginning of treatment. Hepatic donor (n = 2). In the other six patients, transplantation was function returned to baseline values within 10 d from the not performed either because patients relapsed while searching occurrence of liver toxicity in all patients. No significant for an unrelated donor (five children) or because of parents’ cardiac dysfunction and/or abnormalities developed during refusal. The median time interval between beginning of the study period. treatment on study and HSCT was 1Æ8 months (range 1Æ2–4). Haematological toxicity as evidenced by profound myelo- No case of hepatic VOD was recorded after transplantation. By suppression usually lasting longer than 20 d was observed. The contrast, none of the patients who had CRp, PR or who did not median time to neutrophil (defined as an absolute granulocyte respond to the treatment with clofarabine, cyclophosphamide count >0Æ5 · 109/l) and platelet recovery (defined as an and etoposide received an allograft due to disease progression. absolute platelet count >25 · 109/l) was 26 d (range, 18–42) Four out of the seven patients who were transplanted after and 28 d (range, 18–57), respectively. having achieved CR are currently alive (three of them disease- Almost 85% of the patients developed at least one episode of free) with a median follow-up of 8 months (range, 4–17). fever of unknown origin (FUO). Among documented infec- The probability of survival 18 months from the beginning of tions, six patients developed pneumonia and two had septi- treatment for the entire cohort of patients was 20% (95%CI, caemia. Probable fungal pneumonia was diagnosed in three 0–39%) as illustrated in Fig 1. Patients with BCP ALL had a out of the six patients who developed pneumonia. Of the 25 significantly better probability of survival in comparison to children enrolled in the study, 16 (64%) died. All deaths were those with T-ALL (33%, 95%CI, 4–62, vs. 0%, respectively, due to disease progression. P <0Æ001) (Fig 2). The 18-month Kaplan–Meier estimate of

Table II. Treatment-related toxicity (N = 25).

Kidney Heart Liver Lung CNS Infections Metabolic/laboratory Mucositis

Grade N (%) N (%) N (%) N (%) N (%) N (%) N (%) N (%)

0 20 (80) 24 (96) 9 (36) 23 (92) 24 (96) 12 (48) 13 (52) 10 (40) 1 3 (12) 1 (4) 4 (16) 1 (4) 0 (0) 5 (20) 4 (16) 3 (12) 2 2 (8) 0 (0) 6 (24) 0 (0) 0 (0) 0 (0) 6 (24) 9 (36) 3 0 (0) 0 (0) 6 (24) 1 (4) 1 (4) 8 (32) 2 (8) 3 (12) 4 0 (0) 0 (0) 0 (0) 0 (0) 0 (0) 0 (0) 0 (0) 0 (0) Total 25 (100) 25 (100) 25 (100) 25 (100) 25 (100) 25 (100) 25 (100) 25 (100)

CNS, central nervous system.

374 ª 2009 Blackwell Publishing Ltd, British Journal of Haematology, 147, 371–378 Clo/CTX/VP-16 for Advanced Childhood ALL

Fig 3. Overall survival from start of treatment by response to Fig 1. Overall survival from start of treatment. treatment.

donor. This combination of agents might also be considered for patients who had previously received allogeneic HSCT. The rationale for combining these three cytotoxic agents lay with the observation that cyclophosphamide induces DNA interstrand cross-links. These cross-links can be rapidly repaired by leukaemia cells, as demonstrated in chronic lymphocytic leukaemia (CLL) lymphocytes after in vitro exposure to activated cyclophosphamide (Yamauchi et al, 2001). Pre-treatment with clofarabine, leading to inhibition of both ribonucleotide reductase and DNA synthesis and repair, may significantly prevent or even impede completion of DNA strand break repair, resulting in an increase in apoptosis of leukaemia blasts. Support to this hypothesis is provided by a recent report on the combined use of clofarabine and Fig 2. Overall survival from start of treatment by immunophenotype. cyclophosphamide in adults with acute leukaemia, showing that clofarabine followed by cyclophosphamide was associated with increased DNA damage and apoptosis in both myeloid survival for patients who did or did not achieve a CR or CRp and lymphoid blasts obtained both from peripheral blood and was 39% (95%CI, 5–73%) and 0%, respectively (P <0Æ001) BM (Karp et al, 2007). Etoposide binds to topoisomerase II (Fig 3). Among the 14 patients who responded to treatment, and inhibits its function in ligating cleaved DNA molecules leukaemia recurrence was observed in six (43%) patients. The resulting in the accumulation of single- or double-strand DNA median duration of remission for the 14 patients who achieved breaks. This hampers DNA replication and transcription, and either CR or CRp, censoring patients at time of transplanta- promotes apoptotic cell death. tion, was 6 months (range, 3–8Æ5). The median survival The drug dosages chosen for this study were based on the duration of the 11 patients who did not respond to treatment preliminary data presented by Hijiya et al (2007) with some or had PR was 3 months (range, 1–7). modifications, namely a decrease in cyclophosphamide dosage and an increase in etoposide dosage. This scheme proved to be safe and tolerable, as none of the 25 patients enrolled in our Discussion study died due to treatment-related complications. The only This multicentre study showed that, for children with multiple relevant toxicity that we observed was that related to relapsed or resistant ALL, a single combination course of liver dysfunction, although this was never fatal and always clofarabine, cyclophosphamide and etoposide was associated reversible. Hepatic toxicity has been frequently reported when with acceptable organ toxicity and showed promising activity clofarabine was used as single agent, as well as in combination with an OR rate >50%. In addition, this regimen was with other drugs, including cyclophosphamide and cytarabine particularly effective in BCP ALL and induced remission of (Kantarjian et al, 2003; Jeha et al, 2004; Faderl et al, 2005; Jeha sufficient duration to allow many patients with a suitable et al, 2006; Karp et al, 2007; Faderl et al, 2008). In a phase II donor to proceed to HSCT, even from an HLA-disparate extension of the initial escalating dose, phase I study reported

ª 2009 Blackwell Publishing Ltd, British Journal of Haematology, 147, 371–378 375 F. Locatelli et al by Hijiya et al (2007), four out of the eight enrolled patients with T-ALL responded, one with a CR and one with a CRp, given the same combination of drugs, but at slightly different suggesting that further exploration of clofarabine in T-ALL is dosages (i.e. clofarabine 40 mg/m2 per day, cyclophosphamide warranted. It remains to be tested whether relapsed T-ALL 440 mg/m2 per day and etoposide 100 mg/m2 per day, for 5 patients may derive better benefit from alternative experimen- consecutive days), developed severe, life-threatening hepato- tal treatment strategies based on the use of other novel anti- toxicity (three veno-occlusive disease, one hyperbilirubinemia) leukaemia agents such as nelarabine or forodesine (Beesley (Hijiya et al, 2008). In view of these findings, that study was et al, 2007; DeAngelo et al, 2007; Larson, 2007). amended to exclude patients with prior HSCT, viral hepatitis The response achieved with clofarabine was of sufficient and/or cirrhosis, or elevated conjugated bilirubin levels (Hijiya duration to allow many patients with a suitable donor to et al, 2008). There is no obvious explanation for the signifi- proceed to allogeneic HSCT. It is noteworthy that we did not cantly better tolerability of the treatment in our population. It observe any apparent increase in transplantation-related organ is possible that the different dosages of drugs, the prolonged toxicity in the seven patients who were transplanted after hospitalization of our patients and the aggressive policy of having reached CR with the triple combination, including two prophylaxis that we adopted against infections may have patients with a history of prior transplantation at study contributed to the absence of severe, life-threatening toxicity in enrolment. our cohort. Nevertheless, we recommend careful and frequent The current study represents a further step in the develop- monitoring of liver function, as well as avoidance of concom- ment of treatment based on clofarabine in childhood ALL, itant administration for prevention of infection of drugs employing the drug in combination with other cytotoxic known to have potential liver toxicity or pharmacological agents for which a strong pharmacological rationale of interactions, such as voriconazole. combined use exists. In view of its good safety profile and of Infections were a common event observed in this study as the promising results obtained in this population, further would be expected in this heavily pre-treated population with investigation of this regimen is warranted in patients experi- profound and long-standing immune- and myelo-suppression. encing first leukaemia relapse and at very high risk of treatment Indeed, in our patients, 26 d was the median time required to failure (i.e. those belonging to S3/S4 groups of BFM classi- reach neutrophil recovery after treatment. This duration of fication, currently treated with combinations of multiple neutropenia, together with the lympholytic effect displayed by agents including high-dose methotrexate, high-dose cytara- the triple combination of cytotoxic drugs, may have facilitated bine, dexametazone, vincristine, l-asparaginase, fludarabine) the occurrence of infections, especially those of fungal origin. (Einsiedel et al, 2005; Paganin et al, 2008) as well as for Despite the relevant incidence of infectious complications, no children with ALL in first CR and high level of minimal patient died, again possibly thanks to the hospitalization of the residual disease, with the aim of decreasing tumour burden children, and the active monitoring for infections and before transplantation. intensive prophylaxis against bacterial and fungal infections. The combination of clofarabine, cyclophosphamide and Acknowledgements etoposide in this population of patients with advanced childhood ALL was associated with an OR rate of 56%. Of This work was partially supported by grants from AIRC particular interest is the observation that almost half the (Associazione Italiana Ricerca sul Cancro), CNR (Consiglio patients who achieved either CR or CRp were refractory to Nazionale delle Ricerche), MIUR (Ministero dell’Istruzione, their most recent prior regimens. Children with BCP ALL had Universita` e della Ricerca), European Union (FP6 program a greater chance of benefiting from the treatment than those ALLOSTEM) and Fondazione IRCCS Policlinico San Matteo with T-ALL. There is no immediate explanation for the to F.L. association of response to this regimen with the immune phenotype of blast cells. In particular, there was no difference Disclaimers in terms of patients resistant/refractory to the last course of chemotherapy between our children with either BCP- or The authors do not have any potential conflict of interest to T-ALL (data not shown). It is well known that patients with disclose. BM relapse of T-ALL have a dismal prognosis, irrespective of the time elapsing between diagnosis and leukaemia References relapse (Einsiedel et al, 2005; Paganin et al, 2008). It is also possible to speculate that T-ALL blasts are less sensitive to Ascioglu, S., Rex, J.H., de Pauw, B., Bennett, J.E., Bille, J., Crokaert, F., clofarabine-based triple therapy than those belonging to Denning, D.W., Donnelly, J.P., Edwards, J.E., Erjavec, Z., Fiere, D., B-lineage differentiation. In this regard, a recent in vitro study Lortholary, O., Maertens, J., Meis, J.F., Patterson, T.F., Ritter, J., reported that clofarabine appeared to be marginally more Selleslag, D., Shah, P.M., Stevens, D.A. & Walsh, T.J. (2002) Defining opportunistic invasive fungal infections in immunocompromised effective in B-lineage ALL than in T-ALL (Beesley et al, 2007). patients with cancer and hematopoietic stem cell transplants: an It must be also mentioned that in the phase II study of single international consensus. Clinical Infectious Diseases, 34, 7–14. agent clofarabine by Jeha et al (2006), two out of five patients

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