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\begin{document}

\title{Safety Analysis of High-Dose Methotrexate in Pediatric Non-Hodgkin
Lymphomas}



\author[1]{Melanie Bernhardt}%
\author[1]{Austin Brown}%
\author[2]{Austyn Grim}%
\author[3]{Michael Scheurer}%
\author[1]{Nader El-Mallawany}%
\author[1]{Nmazuo Ozuah}%
\affil[1]{Baylor College of Medicine}%
\affil[2]{Texas Children's Hospital}%
\affil[3]{Baylor College of Medicine Department of Pediatrics}%


\vspace{-1em}



  
  \date{May 24, 2024}


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\selectlanguage{english}
\begin{abstract}
High-dose methotrexate (HD-MTX) with rigorous supportive care is
essential to the treatment of pediatric non-Hodgkin lymphomas (NHL). We
describe the safety and tolerability of HD-MTX in patients with NHL
treated at our center. In our cohort of 46 patients, the majority had at
least one course of delayed clearance and/or creatinine elevation.
Additionally, more than one-third of patients experienced an episode of
grade [?]3 mucositis. Creatinine elevations and delayed clearance were
independently associated with subsequent grade [?]3 mucositis. We advocate
for greater availability of methotrexate monitoring to allow dose
escalation of this essential modality around the world.%
\end{abstract}%



\sloppy


\section*{Introduction}

{\label{introduction}}

Most children diagnosed with non-Hodgkin lymphoma (NHL) in high-income
countries are expected to achieve long-term survival; however, children
in lower income countries are diagnosed with NHL at a disproportionally
higher rate and do not experience the same chance for cure. {[}1-10{]}
This disparity is related to many factors, including late disease
detection and challenges in delivering high-intensity treatment, such as
methotrexate.{[}3{]} High-dose methotrexate (HD-MTX; 1-8
g/m\textsuperscript{2}) is an essential component of pediatric mature
B-cell and T-cell NHL treatment.{[}11{]} The use of HD-MTX in lower
income countries has been challenging due to treatment-related mortality
at doses of 1-2 g/m\textsuperscript{2}, yet even higher doses are needed
to adequately treat NHL. This discrepancy may reflect differences in
healthcare infrastructure and supportive care interventions which permit
safe administration of HD-MTX, such as real-time monitoring of
methotrexate levels.{[}3{]} Some centers have administered HD-MTX in
sub-Saharan Africa with aggressive supportive care in the absence of
methotrexate monitoring, though with significant treatment-related
toxicity and mortality.{[}1{]} The purpose of this study was to describe
the real-world clinical safety of HD-MTX in patients with NHL where
aggressive supportive care was readily available. Our overarching goal
is to provide a greater understanding of the safety of HD-MTX in NHL, to
inform potential treatment approaches in limited resource settings.

\section*{Methods}

{\label{methods}}

This retrospective chart review evaluated pediatric patients with mature
B/T-cell NHL who received intravenous HD-MTX (3
g/m\textsuperscript{2}/dose intravenously over 3 hours) from October 1,
2010 through June 30, 2020 at Texas Children's Hospital. Patients were
excluded from data analysis if they received an empiric methotrexate
dose reduction. All data were abstracted from the electronic health
record, including diagnosis, race/ethnicity, age, height and weight at
diagnosis; dose and timing of HD-MTX administration; relevant laboratory
details (i.e., serum creatinine, methotrexate levels, urine pH and
specific gravity); select supportive care interventions (i.e.,
leucovorin, hydration, alkalization, glucarpidase, concomitant
medications); tumor lysis syndrome; and vital status. Body surface area
and body mass index were calculated from extracted variables. The
primary outcome was delayed methotrexate clearance, defined by a
methotrexate level above the protocol-defined clearance threshold at
hour 48. Secondary outcomes included the time to clearance, frequency of
serum creatinine elevations (i.e., an increase [?]25\% after start of
methotrexate), and incidence of Common Terminology Criteria for Adverse
Events (version 5.0) grade [?]3 mucositis. Planned exploratory analysis
included evaluation of risk factors associated with delayed clearance of
methotrexate, serum creatinine elevations, and mucositis.

The frequency of each methotrexate-associated toxicity was summarized by
the number of methotrexate doses resulting in each toxicity and number
of patients who experienced the toxicity following any HD-MTX. Odds
ratios (ORs) and corresponding 95\% confidence intervals (CIs) for the
associations between clinical characteristics and the development of
each outcome (delayed clearance, creatinine elevations, and mucositis)
were calculated using multivariable mixed-effects logistic regression to
account for repeated measures following each methotrexate infusion
within each patient. A mixed-effects linear regression model was
constructed to evaluate associations with time to methotrexate
clearance. A step-wise selection process was used to identify a
parsimonious model including age, race/ethnicity, and other clinical
features associated (p-value\textless{}0.2) with one or more of the
outcomes in unadjusted models. All analyses were conducted using Stata
SE version 15.1 (College Station, TX) at a two-sided significance level
of 0.05. This study was approved by Institutional Review Board at Baylor
College of Medicine.

\section*{Results}

{\label{results}}

\emph{Patient population}

During the study period, 196 HD-MTX doses were administered to 46 unique
patients. Overall, patients included in the analysis were 39\%
non-Latino White, 33\% Latino, and 24\% non-Latino Black (Table 1). The
mean age of the cohort was 10.5 years at diagnosis, and a majority
patients were male (n=34; 74\%). The most common oncologic diagnosis was
anaplastic large cell lymphoma (ALCL; n=25, 54\%), followed by 21
patients (46\%) with mature B-NHL, and one patient with peripheral
T-cell lymphoma, NOS. The median number of HD-MTX doses per patient was
4 (range: 1 to 6). All patients were treated on or according to one of
the following protocols: ALCL99, ANHL12P1, ANHL01P1, and ANHL1131.{[}8,
10, 12, 13{]} All patients received protocol-defined supportive care as
previously described,{[}8, 10, 12, 13{]} including intravenous hydration
with alkalinized intravenous fluids, urine pH and output goals,
scheduled leucovorin rescue, serum creatinine trending, and methotrexate
serum level monitoring at hours 24, 48 and at least every 24 hours until
methotrexate level \textless{}0.1 or 0.15 \selectlanguage{greek}μ\selectlanguage{english}M/L (per protocol).
Supportive care interventions for methotrexate clearance were adjusted
to achieve therapeutic goals per institutional practice or clinical
trial protocol. Patients were counseled on good oral care and given a
salt and soda mouthwash for mucositis prevention. Forty-one patients
were alive at the time of data extraction (89\%). No patient died due to
methotrexate-related toxicity.

\emph{Toxicities}

Methotrexate cleared on time in 76.5\% of doses (Table 2). The 46 doses
which resulted in delayed clearance occurred in 26 patients (56.5\%). Of
these, methotrexate cleared by hour 72 in 26 doses, with 20 doses
clearing beyond hour 72 (range: 84 to 256 hours). Grade [?]3 mucositis
occurred following 25 doses of HD-MTX (13\% of all doses administered)
in 18 patients (39.1\%). Serum creatinine elevations occurred during 48
HD-MTX doses (24\%) in 27 patients (58.7\%). Creatinine elevations were
transient and returned to baseline in all patients, due to early
recognition and appropriate increases in hydration. Creatinine
elevations were significantly associated (p\textless{}0.001) with an
increased likelihood of delayed clearance (OR=4.44, 95\% CI: 1.82-10.84)
after accounting for clinical factors. Additionally, creatinine
elevations (OR=4.36, 95\% CI: 1.44-13.25) and delayed clearance
(OR=6.24, 95\% CI: 2.17-17.95) were independently associated with
subsequent grade [?]3 mucositis. No patient required glucarpidase for
methotrexate toxicity or delayed clearance. There was no observed
association between race/ethnicity and time to clearance, serum
creatinine elevations, or mucositis. There was an observed association
(p\textless{}0.05) of self-reported Latino ethnicity and shorter time to
clearance, as well as a potentially increased time to clearance in
patients receiving R-CYM cycles in ANHL01P1 and ANHL1131, and an
increased risk of serum creatinine elevations observed during
methotrexate in patients receiving courses of R-COPADM in ANHL01P1 and
ANHL1131.

\section*{Discussion}

{\label{discussion}}

We describe the clinical safety of HD-MTX in a cohort of children and
adolescents with NHL treated with routine clinical care at a large
tertiary center. We found that about a quarter of HD-MTX doses resulted
in delayed clearance, though overall more than half of all patients
experienced this during treatment. Similarly, about a quarter of all
doses were associated with methotrexate-related serum creatinine
elevations, again impacting more than half of all patients. Although
18\% of doses were complicated by grade [?]3 mucositis, this impacted
nearly 40\% of patients in our cohort. Importantly, creatinine
elevations and delayed clearance were independently associated with
subsequent grade [?]3 mucositis, signifying the importance of early
recognition and intervention in patients receiving HD-MTX. Our data are
limited by the retrospective, single-center study design and relatively
small sample size. In our practice, we can rapidly respond to
methotrexate levels and serum creatinine elevations by adjusting
intravenous fluids and/or modifying leucovorin rescue, potentially
preventing therapeutic morbidity and mortality, though this takes
considerable resources (staffing, laboratory capability, and clinical
expertise). We strongly advocate for expanded access to methotrexate
therapeutic monitoring globally, such that children in limited resource
settings, who are most prominently impacted by NHL are given equitable
access to this essential modality.

\textbf{Conflict of Interest statement:}

This research was funded in part by the National Cancer Institute
(Austin L. Brown: K07CA218362; M. Brooke Bernhardt and Michael E.
Scheurer: U54CA254569) and St. Baldrick's Foundation (Nmazuo Ozuah: SBIF
International Scholar). Dr. Bernhardt has received research support and
has served on an advisory board for BTG International, both unrelated to
this work. All other authors have nothing to disclose.

\section*{References}

{\label{references}}

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2. Smith, M.A., et al., \emph{Declining childhood and adolescent cancer
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11. Reiter, A., et al., \emph{Improved treatment results in childhood
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12. Wrobel, G., et al., \emph{Safety assessment of intensive induction
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\textbf{Hosted file}

\verb`MTX NHL Table 1.docx`  available at \url{https://authorea.com/users/464487/articles/559338-safety-analysis-of-high-dose-methotrexate-in-pediatric-non-hodgkin-lymphomas}

\textbf{Hosted file}

\verb`MTX NHL Table 2.docx`  available at \url{https://authorea.com/users/464487/articles/559338-safety-analysis-of-high-dose-methotrexate-in-pediatric-non-hodgkin-lymphomas}

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