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\begin{document}

\title{Integrating Irinotecan in standard chemotherapy: a novel dose density
combination for High-Risk pediatric Sarcomas}



\author[1]{Gianni Bisogno}%
\author[2]{Andrea Ferrari}%
\author[1]{Arianna Tagarelli}%
\author[1]{Silvia Sorbara}%
\author[2]{Stefano Chiaravalli}%
\author[1]{Elena Poli}%
\author[3]{Giovanni  Scarzello}%
\author[1]{Federica De Corti}%
\author[2]{Michela Casanova}%
\author[1]{Maria Carmen Affinita}%
\affil[1]{Padua University Hospital}%
\affil[2]{Fondazione IRCCS Istituto Nazionale dei Tumori}%
\affil[3]{Istituto Oncologico Veneto Istituto di Ricovero e Cura a Carattere Scientifico}%


\vspace{-1em}



  
  \date{May 25, 2024}


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\selectlanguage{english}
\begin{abstract}
BACKGROUND: Irinotecan is a drug active against pediatric sarcomas with
a toxicity profile that theoretically allows for its association with
more myelotoxic drugs. We examined the feasibility of a dose-density
strategy integrating irinotecan in standard chemotherapy regimens for
patients with high-risk sarcomas. METHODS: Between November 2013 and
January 2020, 23 patients \textless{} 21 years old with metastatic (11
children) or recurrent (12 children) sarcomas were treated with 9
IrIVA/IrVAC cycles. All newly-diagnosed patients received IrIVA
(ifosfamide 3g/m2 on days 1 and 2, vincristine 1.5 mg/m2 on day 1,
actinomycin D 1.5 mg/m2 on day 1, irinotecan 20 mg/m2 for 5 consecutive
days starting on day 8). Two relapsed patients received IrIVA and 10
IrVAC (cyclophosphamide 1.5 g/m2 on day 1 instead of ifosfamide).
Feasibility was assessed in terms of toxicity and time to complete the
treatment. RESULTS: 17 rhabdomyosarcomas, 4 Ewing sarcomas, 2
desmoplastic round cell tumors received a total of 181 cycles (range
2-10). Grade 4 neutropenia occurred in 62.4\% of the cycles. 13 patients
had febrile neutropenia. Diarrhea occurred in 14 cycles. The median time
to complete the treatment was 195 days (range 170-231), 83.4\% of cycles
were administered on time or with a delay \textless{}1 week. With a
median follow-up of 2.6 years (range 0.2-5.0), 12 patients are alive, 9
complete remissions, 3 with the disease. Conclusions: A dose density
strategy combining irinotecan with standard chemotherapy is feasible.
This approach will be investigated in the next trial coordinated by the
European pediatric Soft tissue sarcoma Study Group.%
\end{abstract}%



\sloppy


\textbf{INTRODUCTION}

Sarcomas represent a heterogeneous group of rare tumors with a variety
of histological and biological characteristics and different prognosis.
In pediatric age, rhabdomyosarcoma (RMS) is the most common histotype.
Like Ewing sarcoma (ES) and desmoplastic small round cell tumors
(DSRCT), RMS is a high-grade tumor with a strong tendency for local
invasiveness and metastatic spread. These tumors are currently treated
using a multidisciplinary approach that includes surgery, radiotherapy,
and intensive multi-agent chemotherapy. While the outcome of treatment
for patients with localized RMS and ES is generally a 70-80\% survival
rate, the outcome remains unsatisfactory for patients with distant
metastases and those who relapse (1) (2). Patients with DSRCT still
carry a poor prognosis in most cases (3) and, together with those who
have metastatic or relapsed RMS and ES, form a high-risk group for whom
new treatment approaches need to be investigated.

The use of new drugs to target specific molecular alterations is an
attractive approach for poor prognosis sarcomas. However, at this time,
the activity data of these new agents is still limited (4) (5). An
improvement in the outcome of children with high-risk sarcomas may also
be pursued by optimizing the use of already-available drugs known to be
active against this disease. The treatment of pediatric sarcomas is
currently based on administering chemotherapy cycles containing multiple
drugs every three weeks. It may be that cancer cells start growing again
during the interval between chemotherapy cycles and develop a resistance
to the drugs administered.

Reducing the time between chemotherapy cycles to intensify the treatment
has proved feasible and effective in the treatment of ES (6) and, to
some degree, for metastatic RMS (7). Higher treatment intensity can also
be achieved by increasing the dosage of drugs per unit of time,
according to the so-called dose-density approach.

Irinotecan is active against various pediatric tumors, including RMS and
other sarcomas (8). As it is relatively non-myelotoxic, we hypothesized
that it might be associated with other more myelotoxic drugs.

In this study, we explored the feasibility of a dose-density strategy
for patients with high-risk soft-tissue sarcomas that involved a novel
combination of irinotecan with a more standard regimen based on
alkylating agents. This represents a proof of concept that will be
further investigated in the next multicenter trial coordinated by the
European pediatric Soft tissue sarcoma Study Group (EpSSG).

METHOD

This study included patients with a histologically confirmed diagnosis
of RMS, ES, or DSRCT with metastasis at diagnosis or with
relapsed/refractory disease. To be eligible, patients had to be
\textgreater{}6 months and [?] 21 years old, and have: a Karnofsky
performance status of 70-100\% (for patients \textgreater{}12 years old)
or a Lansky Play Score of 70-100\% (for patients [?]12 years of age); an
adequate bone marrow function (absolute neutrophil count
[?]1000/mm\textsuperscript{3}, platelet count
[?]100,000/mm\textsuperscript{3}); adequate renal and liver function; and
no active grade \textgreater{}2 diarrhea or uncontrolled infection.

The study was approved by the local ethical committee, and informed
consent was obtained from patients or parents, as appropriate.

The diagnostic workup consisted of CT and/or MRI scans of the primary
tumor, chest CT scan, radionuclide bone scan, bone marrow aspirate, and
biopsy. 18F-fluorodeoxyglucose PET was optional.

TREATMENT

As detailed in Figure 1, the first part of the regimen investigated
consisted of IVA ( ifosfamide at a dose of 3g/m\textsuperscript{2} on
Days 1 and 2 as a 3-hour intravenous infusion (iv) (with sodium
mercaptoethanesulfonate at a dose of 3 g/m\textsuperscript{2} per day
and hyperhydration); vincristine at a dose of 1.5
mg/m\textsuperscript{2} ( maximum, 2 mg) on Day 1 given as a single
bolus dose by intravenous injection; actinomycin at a dose of 1.5
mg/m\textsuperscript{2} (maximum, 2mg) on Day 1 given as a single bolus
by intravenous injection, VAC (vincristine 1.5 mg/m\textsuperscript{2}
iv, actinomycin D 1.5 mg/m\textsuperscript{2} iv, and cyclophosphamide
1.5 mg/m\textsuperscript{2}, all on day 1) currently used respectively
by the EpSSG in Europe, and by the Children's Oncology Group (COG) in
the USA. VAC was administered to patients that received ifosfamide in
the first line. Irinotecan was started on day 8 and given for 5 days
(preferably Monday to Friday to enable its administration in the
outpatient setting), irrespective of blood cell counts, providing the
patient was in good clinical conditions. Since this was the first
attempt to include irinotecan in a dose-density multidrug combination, a
fixed, reduced dose of irinotecan was used (20
mg/m\textsuperscript{2}/day for 5 consecutive days) to gather
information and ascertain whether a subsequent formal phase I trial
would be possible. Diarrhea prophylaxis included the administration of
cefixime 8 mg/kg per os once a day for 9 consecutive days starting on
day 6.

Cycles were administered every 21 days, with neutrophils
\textgreater{}1.0 x 10\textsuperscript{9}/l and platelets to
\textgreater{}100 x 10\textsuperscript{9}/l and following resolution of
non-hematopoietic toxicity. The preventive use of colony-stimulating
factors was not allowed. Tumor response was scheduled to be assessed
after 3 and 9 cycles at the site of both the primary tumor and any
metastases, and more assessments were possible if clinically indicated.
The response was classified as: complete response (CR) = complete
disappearance of all visible disease; partial response (PR) = a tumor
volume reduction of more than two-thirds; minor response (MR) = a tumor
volume reduction of more than one-third, but less than two-thirds. A
reduction in volume of less than one-third was recorded as stable
disease (SD), while an increase in tumor size or the detection of new
lesions was classified as progression of disease (PD)

Local treatment with radiotherapy and/or surgery had to be considered
after the 4\textsuperscript{th} cycle of chemotherapy, but only general
recommendations were given because of the heterogeneity of the study
population. Resection was recommended for primary tumors with/without
metastases, if feasible. Radiotherapy also had to be considered for
primary and metastatic sites in newly-diagnosed metastatic sarcomas. If
possible, re-irradiation was recommended in relapsed patients.

\emph{Toxicity monitoring and recommendations for changes to
chemotherapy}

During chemotherapy, complete blood cell counts and blood chemistry were
obtained at the baseline, weekly, and before each cycle. Toxicity was
graded using the National Cancer Institute's Common Toxicity Criteria
(CTC), version 5.0. In the event of significant diarrhea ([?] CTC grade
III), the dose of irinotecan had to be reduced by 25\% for the
subsequent course. If there were further episodes, the dose had to be
further reduced or even omitted.

Drug doses for younger patients had to be calculated by body surface
area, then reduced by 50\% or 33\% for children under 6 or 12 months
old, respectively.

As a general criterion for evaluating the feasibility of this new
regimen, we established that more than 70\% of cycles would have to be
administered with a delay of less than one week. We also compared the
overall duration of the treatment with a historical series of patients
with metastatic RMS treated in Italy from November 2013 to January 2020
and included in the EpSSG MTS-2008 protocol. These patients received 9
cycles of chemotherapy at 3-week intervals: 4 cycles of the IVADo
regimen (ifosfamide, vincristine, actinomycin D, and doxorubicin)
followed by 5 cycles of IVA (ifosfamide, vincristine, actinomycin D)
(9). These patients subsequently received maintenance therapy with
cyclophosphamide and vinorelbine, but this part of the treatment was not
considered for the purposes of our comparison.

RESULTS

Between November 2013 to January 2020, this study enrolled 23 patients
aged from 1.3 to 25 years

(median 10.9 years), and 15 were male. The study population included 11
newly-diagnosed metastatic sarcomas (10 RMS and 1 DSRCT) and 12 relapsed
tumors (7 RMS, 4 ES, and 1 DSRCT). All patients with metastatic disease
had important metastatic diffusion. The patients with DSRCT had
peritoneal dissemination (Table 1).

All newly-diagnosed patients received the IrIVA combination, while in
the group of relapsed patients, 2 received IrIVA and 10 IrVAC.

\emph{Toxicity}

In total, 181 cycles (range 2-10) were administered, and 173 were
evaluable for toxicity (105 IrIVA and 68 IrVAC cycles). The treatment
was stopped in two patients after 2 and 7 cycles due to tumor
progression, and in another two after 3 and 5 cycles due to the
clinician's or parents' decision. Another patient was given high-dose
chemotherapy.

No toxic deaths occurred. As expected, the most significant toxicity was
myelosuppression. Grade 4 neutropenia was observed in 108 cycles
(62.4\%) and was more frequent in patients receiving IrVAC (72\% of
cycles) than in those given IrIVA (56.1\%). Grade 3 anemia was evident
in 40 cycles (23.1\%), with 14 patients requiring blood transfusions (no
grade 4 anemia was reported). Thrombocytopenia was less severe, with
grade 4 toxicity observed in only 7 cycles (4.0\%), and 4 patients
receiving platelet transfusions (Table1S-2S-3S). There were 33 episodes
of fever during neutropenia (20.2\% of cycles) in 13 patients, and blood
cultures were positive in 4 cases, but without any signs of septic
shock. One patient had an episode of typhlitis, and one had surgery for
appendicitis.

Six patients experienced 19 episodes of grade 3 non-hematological
toxicity (Table 2); no grade 4 episodes were recorded.. Diarrhea
occurred in 14 cycles, with 3 episodes of grade 3 diarrhea in two
patients, one of them experienced two episodes during febrile
neutropenia (in one case a stool test was positive for \emph{Clostridium
difficilis} ). The dose of irinotecan was not reduced in any subsequent
cycles because the patients recovered rapidly. No meaningful difference
in toxicity emerged between patients given IrIVA or IrVAC.

Constipation and peripheral neuropathy prompted a reduction in the dose
of vincristine in 15 cycles. The irinotecan cycles were delayed for more
than one week in 7 cycles, and not administered due to fever and
neutropenia in 2 cycles. The dose of irinotecan was never reduced.
Ifosfamide was replaced with cyclophosphamide in a child suffering from
seizures. Actinomycin was withdrawn during radiotherapy in 7 cycles.

The median interval between cycles was 23 days (range 19-51), with 151
out of 181 cycles (83.4\%) administered on time or without any
significant delay (\textless{}1 week). Considering the patients who
completed the whole chemotherapy treatment (i.e., excluding the 4
patients that prematurely concluded the treatment), the median interval
between the first and ninth cycles was 195 days (range 170-231). On
comparing this outcome with the 40 patients enrolled in the MTS2008
protocol, we found that precisely the same median time - 195 days (range
169-270) -- was taken to complete 9 cycles of chemotherapy.

Nine patients had a delay of more than 30 days, mainly due to local
therapies.

\emph{Outcome}

After the initial three cycles, CR was evident in 3 patients, PR in 15,
and MR in 1. SD was evident in the 2 children with RMS and PD in 2
patients with Ewing sarcoma. Considering the CR and PR alone, the
response rate was 88.2\% (15/17) in cases of RMS. PR was evident in 2/4
patients with relapsed ES and 1/2 patients with DSRCT. The response
rates were 84.6\% (11/13) and 70\% (7/10) for patients treated with
IrIVA and IrVAC, respectively.

With a median follow-up of 2.6 years (range 0.2 -5.0), 12 patients were
still alive at the time of writing, 9 in CR (3 metastatic at diagnosis
and 6 with the relapsing disease) and 3 were alive with disease.

DISCUSSION

In this study, we evaluated the feasibility of a dose density approach
using a chemotherapy combination that aimed to include irinotecan in the
chemotherapy regimens currently used to treat patients with sarcoma, and
especially RMS.

The IVA regimen is now considered the standard chemotherapy in European
trials for non-metastatic RMS. In North America, cyclophosphamide is
used instead of ifosfamide in the VAC regimen. The most significant
toxicity of these two combinations is myelotoxicity in the 2-3 weeks
following their administration. Irinotecan is a drug active against RMS
and, when administered with a continuous schedule (i.e., over 5 days for
1 week), its worst side effect is diarrhea, while myelotoxicity is low.

The IrIVA or IrVAC regimens are, therefore, rational combinations of the
standard IVA/VAC scheme with irinotecan because the activity of the
drugs and their different toxicity profiles theoretically allow an
increase of the chemotherapy intensity without increasing the risk of
toxicity.

This was confirmed in our study. Most of the patients were able to
complete their treatment within a reasonable time. Although IrIVA/IrVAC
are intensive combinations, toxicity was not significantly worse than in
patients treated with IVA in the RMS2005 protocol, where grade 3-4
infections were reported in 57\% of patients, and renal and
gastrointestinal toxicity in 2\% and 8\%, respectively (10). It should
be noted that 47.8\% of the patients in our present study had a relapsed
tumor, so they had already received previous treatments, meaning that a
more significant toxicity might have been expected.

There is limited experience of the dose-density approach against
pediatric sarcoma. An attempt to reduce the interval between cycles
proved feasible, and possibly beneficial, in patients with metastatic
RMS included in the COG protocol ARST0431study was based on the concept
of dose-compression: the cycles of chemotherapy were administered with
an interval of 14 days instead of the 21 as it is used in the standard
treatment. The results showed a possible improvement for patients with
embryonal RMS, but not for those with high-risk features (Oberlin score
\textgreater{}1) (7). More promising results were achieved in localized
ES by adopting the same chemotherapy-intensifying approach and reducing
the interval between cycles to 2 weeks. A randomized study reported a
significantly better outcome in patients treated with chemotherapy
administered after shorter intervals than in those given the same
chemotherapy according to the standard interval (6). New combinations
are under study using the same approach (11).

In our high-risk population, 52\% of patients were alive in CR at the
time of writing, although some have only a short follow-up. This result,
and the limited toxicity reported, indicate that the IrIVA or IrVAC
combinations deserve further testing, possibly in a more homogenous
group of patients with less unfavorable features-as already done for ES
patients (6) (11).

A limitation of our study is that we tested only one dose of irinotecan
(20 mg/m\textsuperscript{2}/day for 5 days). The recommended dose of
irinotecan, when it is used alone or with vincristine, is 50
mg/m\textsuperscript{2} for 5 days. Therefore a proper phase I study is
needed to establish the maximum tolerated dose of irinotecan within this
novel regime.

In conclusion, our study demonstrates that it is feasible to include
irinotecan in the standard chemotherapy regimens used to treat sarcoma,
and its use in this setting deserves further investigation. This will be
one of the goals of the next EpSSG study.

\textbf{Conflict of interest statement}

The authors have no conflicts of interest to disclose.

\textbf{Acknowledgments}

We would like to thank Angela Scagnellato and Beatrice Coppadoro for
their help with data management and analysis.

This work was supported by the Fondazione Lucia Valentini Terrani ONLUS

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Pediatr Blood Cancer.~2016 Mar;63(3):493-8







\section*{Table and figure legends}

{\label{table-and-figure-legends}}

Table 1 -- Patients' characteristics

Table 2: Non-hematological toxicity

Figure 1. The IrIVA regimen

\section*{Supporting Information}

{\label{supporting-information}}

Table 1S: Hematologic toxicity -Whole population (173 cycles)

Table 2S: Hematologic toxicity -Patients treated with IrIVA (Total
number of cycles : 105)

Table3S: Hematologic toxicity -Patients treated with IrVAC(Total number
of cycles: 68)

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\end{center}
\end{figure}

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