Mithramycin for Children and Adults With Solid Tumors or Ewing Sarcoma

BACKGROUND:

- Mithramycin, an anti-tumor antibiotic, underwent broad clinical evaluation in solid
tumors and leukemias in the 1960s and demonstrated activity in some leukemias,
lymphomas, and solid tumors. In particular, mithramycin was found to have activity
against testicular cancers and was briefly used in the clinic for this tumor prior to
the development of the currently used treatment regimen.

- The Ewing Sarcoma Family of Tumors (ESFT) is the second most common malignant bone tumor
of childhood. There has been very little improvement in overall patient survival in past
years, particularly for patients with high risk metastatic or relapsed disease.
Therefore, there is a need for effective novel agents for the treatment of this disease.

- Multiple studies have shown that suppressing the expression of EWS-FLI1 effectively
limits the tumorigenicity of ESFT cells. Laboratory studies have shown that mithramycin
effectively suppresses the activity of EWS-FLI1 both in vitro and in vivo.

OBJECTIVES (PRIMARY):

- Phase I portion of this study is to: determine the tolerability, toxicity, and the
recommended phase II dose of mithramycin in children and adolescents with refractory
extracranial solid tumors.

- Phase II portion of this trial is to: determine the objective response rate (complete
response (CR) and partial response (PR)) of Ewing sarcoma to mithramycin in children and
adults using Response Evaluation Criteria in Solid Tumors (RECIST) criteria when
administered at 17.5 microgram/kg over 6 hours once daily for 7 days to be repeated
every 28 days until unacceptable toxicity or disease progression.

- Phase II portion of this trial to: evaluate if mithramycin inhibits NR0B1 in tumor
tissue and determine changes in gene expression signature pre-treatment and at steady
state on day +4 of treatment in patients greater than or equal to 18 years old with
Ewing sarcoma and EWS/FLI1 fusion transcript with disease amenable to percutaneous
biopsy.

ELIGIBILITY:

- Phase I Portion: children (greater than or equal to 12 months) and adolescents (less
than or equal to 17 years) with recurrent or refractory extracranial solid tumors.

- Phase II Portion in adults: adults (greater than or equal to 18 years of age at
enrollment) with recurrent or refractory measurable extracranial Ewing sarcoma and the
EWS-FLI1 fusion transcript.

- Phase II Portion in children and adolescents: Once the adult dose is deemed safe,
children

(greater than or equal to 12 months) and adolescents (less than or equal to 17 years) with
recurrent or refractory measurable

extracranial Ewing sarcoma and the EWS-FLI1 fusion transcript will begin enrollment to the
Phase II portion.

- Participants must meet safety laboratory criteria and prior therapy limitations.

DESIGN:

Phase I Portion: Mithramycin will be administered in escalating doses to children and
adolescents intravenously over 6 hours once daily for 7 days to be repeated every 28 days
until unacceptable toxicity or disease progression. The cohort at the recommended dose or
maximum tolerated dose (MTD) will be expanded up to 12 patients, and attempts will be made to
enroll 6 patients that are greater than or equal to 12 years of age and 6 patients that are <
12 years of age to gain experience with a broad age range of patients. A maximum of 18
evaluable patients will be enrolled on the phase I portion.

- Phase II Portion: Using a Simon two stage design, mithramycin will be administered
intravenously at 17.5 microgram/kg over 6 hours once daily for 7 days to be repeated
every

28 days until unacceptable toxicity or disease progression to children and adults with
Ewing sarcoma with EWS-FLI1 fusion transcript. Up to 24 evaluable patients will be
enrolled on the phase II portion.

- The Phase I and Phase II portions of the protocol will enroll patients simultaneously.

- INCLUSION CRITERIA

- Diagnosis

- Patients current disease state must be one for which there is no known curative
therapy or therapy proven to prolong survival with an acceptable quality of life.

- Phase I Portion: Measurable or evaluable refractory or recurrent extracranial solid
tumors, excluding brain tumors and cerebral metastases.

- Phase II Portion adults and children: Refractory or recurrent extracranial Ewing
sarcoma with Ewings sarcoma - friend leukemia integration 1 transcription factor
(EWS-FLI1) fusion transcript. Patients enrolled to this cohort must have measurable
disease. Presence of the transcript will be determined during histologic confirmation
of disease with a Clinical Laboratory Improvement Amendments (CLIA) approved EWS-FLI
paraffin assay in the Laboratory of Pathology Center for Cancer Research, National
Cancer Institute (CCR, NCI), unless a pathology report documenting presence of the
transcript using a CLIA approved assay is obtained from the referring institution.

- Histologic confirmation of disease in the Laboratory of Pathology, CCR, NCI, National
Institutes of Health (NIH).

- Age

- Phase I Portion: greater than or equal to 12 months to less than or equal to 17 years

- Phase II Portion in adults initially: greater than or equal to 18 years

- Phase II Portion expanded in pediatrics after determination of phase II dose in
children will include children greater than or equal to 12 months to less than or
equal to 17 years

- Performance Score: Karnofsky (> 10-17 years old) or Lansky (less than or equal to 10
years old) greater than or equal to 50%, or Eastern Cooperative Oncology Group (ECOG)
1 or 2 (adults)

- Prior therapy

- greater than or equal to 2 weeks must have elapsed since local palliative radiation
(XRT) (small port);

- greater than or equal to 24 weeks must have elapsed since prior total body irradiation
(TBI), craniospinal XRT, or if greater than or equal to 50%

- radiation of pelvis;

- greater than or equal to 6 weeks must have elapsed since other substantial BM
radiation;

- greater than or equal to 12 weeks must have elapsed since stem cell transplant or
infusion without TBI and no active graft vs. host disease;

- greater than or equal to 3 weeks must have elapsed from last dose of myelosuppressive
chemotherapy (six

weeks for nitrosoureas);

at least 3 half-lives must have elapsed since monoclonal
antibody1;(https://members.childrensoncologygroup.org/Disc/devtherapeutics/default.asp for
listing of monoclonal antibody half-lives.)

- greater than or equal to 7 days must have elapsed from the last dose of biologic
agents.

- greater than or equal to 7 days since the completion of therapy with a growth factor

- Recovered from acute toxicities of prior therapy to less than or equal to Grade 1;
specifically

a) Hematologic and Coagulation Parameters

i. Peripheral absolute neutrophil count (ANC) greater than or equal to 1000/mcL

ii. Platelets greater than or equal to 75,000/ mcL (transfusion independent)

iii. Hemoglobin greater than or equal to 8 g/dL (packed red blood cell (PRBC) transfusions
permitted)

iv. Normal prothrombin time (PT)/partial thromboplastin time (PTT) with the exception of a
lupus anticoagulant, which is permitted, may be corrected with Vitamin K administration or
transfusion. Fibrinogen greater than or equal to the lower limit of normal.

b) Hepatic Function

i. Bilirubin (total) less than or equal to 1.5 times upper limit of normal (ULN)

ii. Alanine aminotransferase (ALT) (serum glutamic pyruvic transaminase (SGPT) less than or
equal to 3.0 times ULN

iii. Albumin > 2 g/dL

c) Renal Function

i. Creatinine clearance greater than or equal to 60 mL/min/1.73 m^2, or serum creatinine
base on age and gender as follows:

Age (years) Maximum Serum Creatinine (mg/dL)

2 to < 6 0.8 0.8

6 to < 10 1 1

10 to < 13 1.2 1.2

13 to < 16 1.5 1.4

greater than or equal to 16 1.7 1.4

- Normal calcium, magnesium and phosphorus (can be on oral supplementation

- Cardiac Function: Left ventricular ejection fraction (EF) within normal institutional
limits by Echocardiogram or multi-gated acquisition scan (MUGA)

- Ability to give informed consent. For patients < 18 years of age their legal guardian
must give informed consent. Pediatric patients will be included in age appropriate
discussion in order to obtain verbal assent.

- Female and male patients (and when relevant their partners) must be willing to
practice birth control (including abstinence) during and for two months after
treatment, if of childbearing potential during sexual contact with a female of
childbearing potential.

- A durable power of attorney (DPA) will be offered to all patients greater than or
equal to 18 years old.

- Eligibility criteria for mandatory serial tumor biopsies

- Age: greater than or equal to 18 years old

- Ewing sarcoma with EWS-FLI1 fusion transcript

- Hematologic and coagulation parameters within 2 days prior to each biopsy: Normal
PT/PTT with exception of lupus anticoagulant, platelets greater than or equal to
75,000/mcL, peripheral ANC greater than or equal to 750/mcL

- Willing to undergo biopsies, which will only be performed on tumors amenable to
percutaneous biopsy

EXCLUSION CRITERIA:

- Clinically significant systemic illness (e.g. serious active infections or significant
cardiac, pulmonary, hepatic or other organ dysfunction), that in the judgment of the
PI would compromise the patient s ability to tolerate protocol therapy or
significantly increase the risk of complications.

- Patients with a history intracranial Ewing sarcoma including cerebral metastases

- Patients with evidence of active bleeding, intratumoral hemorrhage or history of
bleeding diatheses

- Patients who are receiving anticoagulants other than prophylactic anticoagulation of
venous or arterial access devices, provided that requirements for PT, PTT and
fibrinogen are met, as described

- Investigational Drugs: Patients who are currently receiving another investigational
drug

- Patients who are concurrently receiving agents, which may increase the risk for
mithramycin related toxicities, such as hemorrhage including:

- Thrombolytic agents

- Anti-inflammatory drugs, nonsteroidal (nonsteroidal anti-inflammatory drugs (NSAIDs))
or aspirin or salicylate containing products, which may increase risk of hemorrhage

- Dextran

- Dipyridamole

- Sulfinpyrazone

- Valproic acid

- Anti-cancer Agents: Patients who are currently receiving other anti-cancer agents

- Lactating or pregnant females (due to risk to fetus or newborn, and lack of testing
for excretion in breast milk).

- Patients with history of human immunodeficiency virus (HIV), hepatitis B virus (HBV)
or hepatitis C virus (HCV) due to potentially increased risk of mithramycin toxicity
in this population.

- Hypersensitivity to plicamycin (mithramycin)

- Requirement for any of the contraindicated medications: nonsteroidal anti-inflammatory
drugs, aspirin, dextran or other iron containing solutions (due to incompatibility),
dipyridamole, sulfinpyrazone or valproic acid

- Patients who in the opinion of the investigator may not be able to comply with the
safety monitoring requirements of the study.

- Patients receiving concurrently other therapies directed at their cancer.