\documentclass[10pt]{article}

\usepackage{fullpage}
\usepackage{setspace}
\usepackage{parskip}
\usepackage{titlesec}
\usepackage[section]{placeins}
\usepackage{xcolor}
\usepackage{breakcites}
\usepackage{lineno}
\usepackage{hyphenat}





\PassOptionsToPackage{hyphens}{url}
\usepackage[colorlinks = true,
            linkcolor = blue,
            urlcolor  = blue,
            citecolor = blue,
            anchorcolor = blue]{hyperref}
\usepackage{etoolbox}
\makeatletter
\patchcmd\@combinedblfloats{\box\@outputbox}{\unvbox\@outputbox}{}{%
  \errmessage{\noexpand\@combinedblfloats could not be patched}%
}%
\makeatother


\usepackage{natbib}




\renewenvironment{abstract}
  {{\bfseries\noindent{\abstractname}\par\nobreak}\footnotesize}
  {\bigskip}

\titlespacing{\section}{0pt}{*3}{*1}
\titlespacing{\subsection}{0pt}{*2}{*0.5}
\titlespacing{\subsubsection}{0pt}{*1.5}{0pt}


\usepackage{authblk}


\usepackage{graphicx}
\usepackage[space]{grffile}
\usepackage{latexsym}
\usepackage{textcomp}
\usepackage{longtable}
\usepackage{tabulary}
\usepackage{booktabs,array,multirow}
\usepackage{amsfonts,amsmath,amssymb}
\providecommand\citet{\cite}
\providecommand\citep{\cite}
\providecommand\citealt{\cite}
% You can conditionalize code for latexml or normal latex using this.
\newif\iflatexml\latexmlfalse
\providecommand{\tightlist}{\setlength{\itemsep}{0pt}\setlength{\parskip}{0pt}}%

\AtBeginDocument{\DeclareGraphicsExtensions{.pdf,.PDF,.eps,.EPS,.png,.PNG,.tif,.TIF,.jpg,.JPG,.jpeg,.JPEG}}

\usepackage[utf8]{inputenc}
\usepackage[english]{babel}



\usepackage{float}








\begin{document}

\title{Thromboembolic toxicity observed with concurrent trametinib and
lenalidomide therapy}



\author[1]{Priya Chan}%
\author[2]{Ashley Sabus}%
\author[3]{Molly Hemenway}%
\author[3]{Kathryn Chatfield}%
\author[3]{Christina  White }%
\author[3]{David Mirsky}%
\author[3]{Nicholas Foreman}%
\author[3]{Nathan Dahl}%
\affil[1]{University of Utah School of Medicine}%
\affil[2]{Children's Hospital Colorado}%
\affil[3]{University of Colorado - Anschutz Medical Campus}%


\vspace{-1em}



  
  \date{May 24, 2024}


\begingroup
\let\center\flushleft
\let\endcenter\endflushleft
\maketitle
\endgroup





\selectlanguage{english}
\begin{abstract}
The event-free survival of pediatric low-grade gliomas is poor, and
patients often require multiple treatment strategies. While MEK and RAF
inhibitors are efficacious in early-phase trials, not all patients
respond and many experience progression following completion of therapy.
Evaluating combination therapies that may enhance efficacy or prolong
disease stabilization is warranted. We report our institutional
experience using concurrent trametinib and lenalidomide in the treatment
of primary pediatric central and peripheral nervous system tumors. Two
of four patients using this combination therapy experienced severe
thromboembolic events necessitating discontinuation of therapy. This
combination requires further investigation, and we urge caution if used.%
\end{abstract}%



\sloppy


Thromboembolic toxicity observed with concurrent trametinib and
lenalidomide therapy Priya P. Chan MD\textsuperscript{1}, Ashley Sabus
PharmD, BCOP\textsuperscript{2}, Molly S. Hemenway MS,
PNP\textsuperscript{3}, Kathryn C. Chatfield MD\textsuperscript{3},
Christina J. White DO\textsuperscript{4}, David M. Mirsky
MD\textsuperscript{4}, Nicholas K. Foreman MD\textsuperscript{3}, Nathan
A. Dahl MD\textsuperscript{3}

\textsuperscript{1}Department of Pediatrics, University of Utah, Salt
Lake City, Utah

\textsuperscript{2}Department of Pharmacy, Children's Hospital Colorado,
University of Colorado Anschutz Medical Campus, Aurora, Colorado

\textsuperscript{3}Department of Pediatrics, Children's Hospital
Colorado, University of Colorado Anschutz Medical Campus, Aurora,
Colorado

\textsuperscript{4}Department of Radiology, Children's Hospital
Colorado, University of Colorado Anschutz Medical Campus, Aurora,
Colorado

\textbf{Corresponding Author:} Priya Chan, MD 100 N Mario Capecchi
Drive, SLC, UT 84113

Phone (612) 251-6318, Fax (801) 662-4717

Priya.Chan@hsc.utah.edu

\textbf{Word count:}

Abstract: 100

Main text: 1194

\textbf{The number of Tables, Figures and Supporting Information files:}

Figures: 2

\textbf{Short running title:}

Thromboembolic toxicity with concurrent trametinib and lenalidomide

\textbf{Keywords:}

Trametinib, Lenalidomide, Thromboembolic toxicity

\textbf{Abbreviations:}\selectlanguage{english}
\begin{longtable}[]{@{}ll@{}}
\toprule
CNS & Central nervous system\tabularnewline
\midrule
\endhead
DVT & Deep vein thrombosis\tabularnewline
EFS & Event-free survival\tabularnewline
LVEF & Left ventricular ejection fraction\tabularnewline
MAPK & Mitogen-activated protein kinase\tabularnewline
MRI & Magnetic resonance imaging\tabularnewline
OS & Overall survival\tabularnewline
PD & Progressive diseases\tabularnewline
PE & Pulmonary embolism\tabularnewline
pLGG & Pediatric low-grade glioma\tabularnewline
PNS & Peripheral nervous system\tabularnewline
SD & Stable disease\tabularnewline
STR & Subtotal resection\tabularnewline
\bottomrule
\end{longtable}

\textbf{Abstract}

The event-free survival of pediatric low-grade gliomas is poor, and
patients often require multiple treatment strategies. While MEK and RAF
inhibitors are efficacious in early-phase trials, not all patients
respond and many experience progression following completion of therapy.
Evaluating combination therapies that may enhance efficacy or prolong
disease stabilization is warranted. We report our institutional
experience using concurrent trametinib and lenalidomide in the treatment
of primary pediatric central and peripheral nervous system tumors. Two
of four patients using this combination therapy experienced severe
thromboembolic events necessitating discontinuation of therapy. This
combination requires further investigation, and we urge caution if used.

\textbf{Introduction} Pediatric low-grade gliomas (pLGGs) are the most
common central nervous system (CNS) tumors in
childhood.\textsuperscript{1} Outcomes for pLGGs are generally
excellent, with a 20-year overall survival (OS) between
85-96\%.\textsuperscript{2-4} However, event-free survival (EFS) is
poor, with data from Children's Oncology Group A9952 demonstrating an
EFS of 45\% for all patients.\textsuperscript{5} Patients consequently
often require multiple treatment strategies.

Complete surgical resection is the mainstay of treatment, however, often
is not feasible due to tumor location. Carboplatin-containing
chemotherapy regimens are the standard upfront therapy for pLGGs, but
there is no consensus on treatment following
recurrence.\textsuperscript{5-10}

The hallmark of pLGGs are genetic aberrations of the mitogen-activated
protein kinase (MAPK) pathway, which lead to constitutive pathway
activation.\textsuperscript{11-14} MEK and RAF inhibitors target this
pathway and are well tolerated and efficacious in reducing tumor size
and improving EFS in phase 1 and 2 trials in patients with recurrent
pLGGs.\textsuperscript{15-19} However, not all patients respond to
monotherapy, and many experience progression after completion of
therapy.~Thus, evaluating combination therapies that may enhance
efficacy or prolong disease stabilization is warranted.

Lenalidomide is an immunomodulatory agent with CNS penetration that
functions through anti-angiogenic, anti-inflammatory, and pro-apoptotic
effects, making it a promising candidate for the treatment of pediatric
CNS tumors. Lenalidomide is well-tolerated in ongoing phase I trials for
recurrent pediatric malignancies, with an anti-tumor effect demonstrated
in recurrent pediatric CNS tumors.\textsuperscript{20-22} Given their
distinct mechanisms of action, concurrent MEK inhibitors and
lenalidomide may present a rational combinatorial therapy. Further, both
have available safety and dosing data in pediatric patients. Here we
describe our institutional experience treating pediatric patients with a
MEK inhibitor and lenalidomide concurrently, which to our knowledge has
not been described.

\textbf{Methods}

A retrospective review of medical records of patients with primary CNS
or peripheral nervous system (PNS) malignancies treated at Children's
Hospital Colorado to identify children treated with MEK inhibitors and
lenalidomide concurrently.

\textbf{Results} We identified four pediatric patients with primary CNS
or PNS tumors treated with concurrent trametinib (0.032 mg/kg/day for
patients less than 6 years old; 0.025 mg/kg/day for patients 6 years and
older) and lenalidomide (25 mg/m\textsuperscript{2}/day on days 1-21 of
each 28-day cycle).

\emph{Case 1}

A 10-year-old boy had been diagnosed with an optic chiasm pilomyxoid
astrocytoma (WHO grade II, BRAF:KIAA1549 fusion-positive). Prior therapy
included subtotal resection (STR), carboplatin and vinblastine, focal
photon radiation to 54 Gy, and trametinib. After three months of
trametinib, he experienced progressive disease (PD) and started
lenalidomide in addition to trametinib. Adverse effects on this
combination were limited to grade 1 rash and paronychia. He achieved 15
months of stable disease (SD) on combination therapy before experiencing
PD, prompting discontinuation of this therapy.

\emph{Case 2} A 6-year-old boy had been diagnosed with an optic pathway
pilomyxoid astrocytoma (WHO grade II, BRAF:KIAA1549 fusion-positive).
Prior therapy included carboplatin and vinblastine, everolimus, and two
courses of trametinib.

At five years of age, six months into his second course of trametinib,
he experienced PD and subsequently started lenalidomide in addition to
trametinib. After three months of combination therapy, magnetic
resonance imaging (MRI) of the brain demonstrated a partial response.
Seven months into combination therapy, trametinib and lenalidomide were
held due to urgent ventriculoperitoneal shunt revision. Within 48 hours,
he experienced near-complete vision bilateral loss. MRI of the brain
demonstrated a left posterior watershed territory hypoxic-ischemic
injury (Figure 1), with stable appearance of the optic pathway mass.
Multidisciplinary stroke team evaluation did not deem the area of injury
plausibly attributable to direct surgical manipulation or
tumor-associated vascular compression. Echocardiogram was negative for
thrombus. He discontinued trametinib and lenalidomide and started
radiation therapy.

\emph{Case 3} A 11-year-old girl was diagnosed with an optic pathway
pilomyxoid astrocytoma (WHO grade II, BRAF:KIAA1549 fusion-positive).
Prior therapy included carboplatin and vincristine, vinblastine
monotherapy, carboplatin, vinblastine and cetuximab, and focal photon
radiation to 54 Gy before starting trametinib. She received 15 months of
trametinib with continued gradual PD before starting on lenalidomide.
After four months of combination therapy, MRI of the brain demonstrated
SD. However, surveillance echocardiogram identified severe biventricular
dysfunction with a left ventricular ejection fraction (LVEF) of 18\%,
fractional shortening of 9\%, and two mural thrombi in the left
ventricular apex (Figure 2); the right ventricle was also moderately
depressed. Echocardiograms performed prior to lenalidomide initiation
demonstrated normal biventricular function. Trametinib and lenalidomide
were discontinued, and she started enoxaparin and losartan. Within two
weeks, the thrombi were no longer detectable by echocardiogram, and
after two months, LVEF had recovered to 53\%.

\emph{Case 4}

A 15-year-old girl with neurofibromatosis type I received imatinib, STR,
and trametinib to manage a multiply-progressive plexiform neurofibroma
(PN).

After 26 months of trametinib with continued gradual PD, lenalidomide
was added to her therapy. She experienced SD for 12 months with no
attributable adverse effects. The combination was held in preparation
for resection of her PN. Given the safety concerns following the
thromboembolic events described above, the decision was made to restart
lenalidomide only.

\textbf{Discussion}

Recurrent pLGGs represent a therapeutic challenge. Exhaustion of
evidence-based regimens may lead to off-study use of experimental
therapies or combinations. Multiple studies support the use of MEK
inhibitors and lenalidomide alone to treat pLGGs, but to date, there is
no clinical trial evaluating this combination\textsuperscript{15-19,21}.
We describe four patients treated with concurrent trametinib and
lenalidomide for multiply-progressive CNS or PNS tumors. Each patient
had previously tolerated monotherapy with trametinib. However, two of
four patients experienced significant thromboembolic events, requiring
termination of this combination regimen.

Thromboembolic events have not been described in case reports or
early-phase clinical trials of single-agent trametinib or lenalidomide
in pediatric patients with CNS
tumors.\textsuperscript{17,20,21,23-27}The risk for thrombosis in adults
treated with trametinib or lenalidomide monotherapy is also extremely
low.\textsuperscript{28-30}However, deep vein thrombosis (DVT) and
pulmonary embolism (PE) were observed when trametinib was combined with
the BRAF inhibitor, dabrafenib, for treatment of melanoma or non-small
cell lung cancer.\textsuperscript{31}

Similarly, immunomodulatory agents are associated with an increased risk
for myocardial infarction, stroke, DVT, and PE in adults with multiple
myeloma when used concomitantly with dexamethasone or
chemotherapy.\textsuperscript{32,34} The proposed mechanism for
hypercoagulability is poorly understood but likely involves decreases in
anticoagulant proteins and increases in platelet
aggregation.\textsuperscript{35} This may be potentiated by other
prothrombotic agents, such as high-dose dexamethasone, as well as the
direct action of immunomodulatory agents on endothelial cells previously
damaged by chemotherapy.\textsuperscript{32}

Cardiotoxicity has been associated with MEK and BRAF inhibitors and is
thought to result from interference with the MAPK pathway, which may
have a cardioprotective role.\textsuperscript{31} Disruption of vascular
endothelial growth factor signaling via downstream blockade of MEK leads
to decreased nitric oxide production, thereby contributing to
vasoconstriction, hypertension, and an imbalance between pro and
anti-thrombotic factors. Angiogenesis, cellular apoptosis, and
remodeling of myocytes may also rely on normal MAPK function.

This is the first report of trametinib used concomitantly with
lenalidomide; thus, no pharmacodynamic data is available for the
combination. Although the side effect profiles for each agent are
unique, MEK inhibitor-induced cardiotoxicity combined with the
prothrombotic properties of immunomodulatory agents may additively
contribute to the risk for thrombosis in patients treated with
trametinib and lenalidomide concurrently. Given the severe
thromboembolic events experienced by these patients treated with
concomitant trametinib and lenalidomide, this combination requires
further investigation, and we urge caution if used concurrently.

\textbf{Conflict of Interest Statement:}

The authors declare no conflicts of interest.

\textbf{References}

1. Ostrom QT, Cioffi G, Gittleman H, et al. CBTRUS Statistical Report:
Primary Brain and Other Central Nervous System Tumors Diagnosed in the
United States in 2012-2016. \emph{Neuro Oncol.} 2019;21(Suppl
5):v1-v100.

2. Bandopadhayay P, Bergthold G, London WB, et al. Long-term outcome of
4,040 children diagnosed with pediatric low-grade gliomas: an analysis
of the Surveillance Epidemiology and End Results (SEER)
database.\emph{Pediatr Blood Cancer.} 2014;61(7):1173-1179.

3. Krishnatry R, Zhukova N, Guerreiro Stucklin AS, et al. Clinical and
treatment factors determining long-term outcomes for adult survivors of
childhood low-grade glioma: A population-based study.
\emph{Cancer.}2016;122(8):1261-1269.

4. Gnekow AK, Falkenstein F, von Hornstein S, et al. Long-term follow-up
of the multicenter, multidisciplinary treatment study HIT-LGG-1996 for
low-grade glioma in children and adolescents of the German Speaking
Society of Pediatric Oncology and Hematology. \emph{Neuro
Oncol.}2012;14(10):1265-1284.

5. Ater JL, Zhou T, Holmes E, et al. Randomized study of two
chemotherapy regimens for treatment of low-grade glioma in young
children: a report from the Children's Oncology Group. \emph{J Clin
Oncol.} 2012;30(21):2641-2647.

6. Aquino VM, Fort DW, Kamen BA. Carboplatin for the treatment of
children with newly diagnosed optic chiasm gliomas: a phase II
study.\emph{J Neurooncol.} 1999;41(3):255-259.

7. Packer RJ, Ater J, Allen J, et al. Carboplatin and vincristine
chemotherapy for children with newly diagnosed progressive low-grade
gliomas. \emph{J Neurosurg.} 1997;86(5):747-754.

8. Packer RJ, Lange B, Ater J, et al. Carboplatin and vincristine for
recurrent and newly diagnosed low-grade gliomas of childhood. \emph{J
Clin Oncol.} 1993;11(5):850-856.

9. Ronghe M, Hargrave D, Bartels U, et al. Vincristine and carboplatin
chemotherapy for unresectable and/or recurrent low-grade astrocytoma of
the brainstem. \emph{Pediatr Blood Cancer.} 2010;55(3):471-477.

10. Nellan A, Wright E, Campbell K, et al. Retrospective analysis of
combination carboplatin and vinblastine for pediatric low-grade
glioma.\emph{J Neurooncol.} 2020;148(3):569-575.

11. Chen YH, Gutmann DH. The molecular and cell biology of pediatric
low-grade gliomas. \emph{Oncogene.} 2014;33(16):2019-2026.

12. Dougherty MJ, Santi M, Brose MS, et al. Activating mutations in BRAF
characterize a spectrum of pediatric low-grade gliomas. \emph{Neuro
Oncol.} 2010;12(7):621-630.

13. Zhang J, Wu G, Miller CP, et al. Whole-genome sequencing identifies
genetic alterations in pediatric low-grade gliomas. \emph{Nat
Genet.}2013;45(6):602-612.

14. Ryall S, Zapotocky M, Fukuoka K, et al. Integrated Molecular and
Clinical Analysis of 1,000 Pediatric Low-Grade Gliomas. \emph{Cancer
Cell.} 2020;37(4):569-583.e565.

15. Banerjee A, Jakacki RI, Onar-Thomas A, et al. A phase I trial of the
MEK inhibitor selumetinib (AZD6244) in pediatric patients with recurrent
or refractory low-grade glioma: a Pediatric Brain Tumor Consortium
(PBTC) study. \emph{Neuro Oncol.} 2017;19(8):1135-1144.

16. Fangusaro J, Onar-Thomas A, Young Poussaint T, et al. Selumetinib in
paediatric patients with BRAF-aberrant or neurofibromatosis type
1-associated recurrent, refractory, or progressive low-grade glioma: a
multicentre, phase 2 trial. \emph{Lancet Oncol.} 2019;20(7):1011-1022.

17. Perreault S, Larouche V, Tabori U, et al. A phase 2 study of
trametinib for patients with pediatric glioma or plexiform neurofibroma
with refractory tumor and activation of the MAPK/ERK pathway:
TRAM-01.\emph{BMC Cancer.} 2019;19(1):1250.

18. Kieran MW, Hargrave DR, Cohen KJ, et al. Phase 1 study of dabrafenib
in pediatric patients (pts) with relapsed or refractory BRAF V600E high-
and low-grade gliomas (HGG, LGG), Langerhans cell histiocytosis (LCH),
and other solid tumors (OST). \emph{Journal of Clinical
Oncology.}2015;33(15\_suppl):10004-10004.

19. Kieran MW, Bouffet E, Broniscer A, et al. Efficacy and safety
results from a phase I/IIa study of dabrafenib in pediatric patients
with BRAF V600--mutant relapsed refractory low-grade
glioma.\emph{Journal of Clinical Oncology.}
2018;36(15\_suppl):10506-10506.

20. Berg SL, Cairo MS, Russell H, et al. Safety, pharmacokinetics, and
immunomodulatory effects of lenalidomide in children and adolescents
with relapsed/refractory solid tumors or myelodysplastic syndrome: a
Children's Oncology Group Phase I Consortium report. \emph{J Clin
Oncol.} 2011;29(3):316-323.

21. Warren KE, Goldman S, Pollack IF, et al. Phase I trial of
lenalidomide in pediatric patients with recurrent, refractory, or
progressive primary CNS tumors: Pediatric Brain Tumor Consortium study
PBTC-018. \emph{J Clin Oncol.} 2011;29(3):324-329.

22. Warren K, Vezina G, Springer L, et al. EPCT-16. LENALIDOMIDE
ACTIVITY IN PILOCYTIC ASTROCYTOMA AND OPTIC PATHWAY GLIOMAS: REPORT ON
CHILDREN'S ONCOLOGY GROUP ACNS1022.
\emph{Neuro-Oncology.}2021;23(Supplement\_1):i50-i50.

23. Paul MR, Pehlivan KC, Milburn M, Yeh-Nayre L, Elster J, Crawford JR.
Trametinib-based Treatment of Pediatric CNS Tumors: A Single
Institutional Experience. \emph{J Pediatr Hematol
Oncol.}2020;42(8):e730-e737.

24. Selt F, van Tilburg CM, Bison B, et al. Response to trametinib
treatment in progressive pediatric low-grade glioma patients. \emph{J
Neurooncol.} 2020;149(3):499-510.

25. Kondyli M, Larouche V, Saint-Martin C, et al. Trametinib for
progressive pediatric low-grade gliomas. \emph{J
Neurooncol.}2018;140(2):435-444.

26. Manoharan N, Choi J, Chordas C, et al. Trametinib for the treatment
of recurrent/progressive pediatric low-grade glioma. \emph{J
Neurooncol.} 2020;149(2):253-262.

27. Hipp SJ, Goldman S, Kaushal A, et al. A phase I trial of
lenalidomide and radiotherapy in children with diffuse intrinsic pontine
gliomas or high-grade gliomas. \emph{J Neurooncol.} 2020;149(3):437-445.

28. Flaherty KT, Robert C, Hersey P, et al. Improved survival with MEK
inhibition in BRAF-mutated melanoma. \emph{N Engl J
Med.}2012;367(2):107-114.

29. Blumenschein GR, Jr., Smit EF, Planchard D, et al. A randomized
phase II study of the MEK1/MEK2 inhibitor trametinib (GSK1120212)
compared with docetaxel in KRAS-mutant advanced non-small-cell lung
cancer (NSCLC)+. \emph{Ann Oncol.} 2015;26(5):894-901.

30. Rajkumar SV. Thalidomide therapy and deep venous thrombosis in
multiple myeloma. \emph{Mayo Clin Proc.} 2005;80(12):1549-1551.

31. Mincu RI, Mahabadi AA, Michel L, et al. Cardiovascular Adverse
Events Associated With BRAF and MEK Inhibitors: A Systematic Review and
Meta-analysis. \emph{JAMA Netw Open.} 2019;2(8):e198890.

\textbf{Figures}

Figure 1:

A) Axial T2-weighted MRI demonstrates a solid and cystic optic pathway
mass (black asterisk) in a 3-year-old boy

B) Axial diffusion-weighted MRI reveals restricted diffusion of the left
posterior quadrant (white arrowheads) consistent with acute ischemia

C) 3D time-of-flight MR angiographic image at that time was normal

Figure 2: A) Apical 4-chamber view of echocardiogram demonstrates two
apical, mural thrombi (white arrows); LA: left atrium, LV: left
ventricle, RA: right atrium, RV: right ventricle

B) Parasternal short-axis view of echocardiogram demonstrates normal LV
dimension with a small to moderate pericardial effusion (white dashed
outline); RA: right atrium, RV: right ventricle\selectlanguage{english}
\begin{figure}[H]
\begin{center}
\includegraphics[width=0.70\columnwidth]{figures/Figure-1/Figure-1}

\end{center}
\end{figure}\selectlanguage{english}
\begin{figure}[H]
\begin{center}
\includegraphics[width=0.70\columnwidth]{figures/Figure-2/Figure-2}

\end{center}
\end{figure}

\selectlanguage{english}
\FloatBarrier
\end{document}

