Background:
Increasing evidence indicates that activation of stem cell gene expression is a common
mechanism by which environmental carcinogens mediate initiation and progression of thoracic
malignancies. Similar mechanisms appear to contribute to extra-thoracic malignancies that
metastasize to the chest. Utilization of pharmacologic agents, which target gene regulatory
networks mediating "stemness" may be novel strategies for treatment of these neoplasms.
Recent studies performed in the Thoracic Epigenetics
Laboratory, National Cancer Institute (NCI), demonstrate that under exposure conditions
potentially achievable in clinical settings, mithramycin diminishes stem cell gene expression
and markedly inhibits growth of lung and esophageal cancer and malignant pleural mesothelioma
(MPM) cells in vitro and in vivo. These findings add to other recent preclinical studies
demonstrating impressive anti-tumor activity of mithramycin in epithelial malignancies and
sarcomas that frequently metastasize to the thorax.
Primary Objectives:
- Phase I component: To determine pharmacokinetics, toxicities, and maximum tolerated dose
(MTD) of mithramycin administered as a continuous 24h infusion in patients with primary
thoracic malignancies or carcinomas, sarcomas or germ cell tumors metastatic to the
chest.
- Phase II component: To determine objective response rates (Complete Response (CR) +
Partial Response (PR) of mithramycin administered as 24h intravenous infusions in
patients with primary thoracic malignancies or carcinomas, sarcomas or germ cell tumors
metastatic to the chest.
Eligibility:
- Patients with measurable inoperable, histologically confirmed lung and esophageal
carcinomas, thymic neoplasms, germ cell tumors, malignant pleural mesotheliomas or chest
wall sarcomas, as well as patients with gastric, colorectal or renal cancers and
sarcomas metastatic to the thorax are eligible.
- Patients with favorable germline single nucleotide polymorphisms (SNPs) in ATP Binding
Cassette Subfamily B Member 4 (ABCB4), ATP Binding Cassette Subfamily B Member 11
(ABCB11), Ral binding protein (RALBP) or Cytochrome P450 Family 8 Subfamily B Member 1
(CYP8B1) that are associated with resistance to mithramycin-induced hepatotoxicity.
- Patients must have had or refused first-line standard therapy for their malignancies.
- Patients must be 18 years or older with an Eastern Cooperative Oncology Group (ECOG)
performance status of 0 - 2, without evidence of unstable or decompensated myocardial
disease. Patients must have adequate pulmonary reserve evidenced by forced expiratory
volume (FEV1) and diffusing capacity for carbon monoxide (DLCO) equal to or greater than
30% predicted; Oxygen saturation >= 92% on room air. ABG will be drawn if clinically
indicated.
- Patients must have a platelet count greater than or equal to 100,000, an absolute
neutrophil count (ANC) equal to or greater than 1500 without transfusion or cytokine
support, a normal prothrombin time (PT)/partial thromboplastin time (PTT), and adequate
hepatic function as evidenced by a total bilirubin of < 1.5 x upper limits of normal
(ULN) and aspartate aminotransferase (AST)/alanine aminotransferase (ALT) <= 3 X ULN.
- Serum creatinine within normal institutional limits or creatinine clearance >= 60
mL/min/1.73 m^2 for patients with creatinine levels above institutional normal.
Design:
- Single arm Phase I dose escalation to define pharmacokinetics, toxicities and maximum
tolerated dose (MTD).
- Patient cohorts will receive 24hour(h) infusions of mithramycin targeting total doses
previously administered during 7 daily six hour infusions at 30-50 mcg/kg.
- The 24h infusions will be administered every 14 days (1 cycle). Four cycles will
constitute one course of therapy.
- Pharmacokinetics and toxicity assessment to define MTD will be assessed during Cycle 1
of the first course of therapy.
- Due to uncertainties regarding potential cumulative toxicities, no intra-patient dose
escalation will be allowed.
- Once MTD has been defined, patients will be enrolled into two cohorts (primary thoracic
malignancy vs neoplasm of non-thoracic origin metastatic to the chest) to determine
clinical response rates at the MTD, using a Simon Optimal Two Stage Design for Phase II
Clinical Trials targeting an objective response rate (Response Evaluation Criteria in
Solid Tumors (RECIST) of 30%.
- Following each course of therapy, patients will undergo restaging studies. Patients
exhibiting objective response to therapy or stable disease by RECIST criteria will be
offered an additional course of therapy.
- Patients exhibiting disease progression will be removed from study.
- Biopsies of index lesions will be obtained at baseline and on Day 4 of the first cycle
of therapy for analysis of pharmacodynamic endpoints. Optional tumor biopsies may be
requested at the completion of Course 1 (4 cycles) and in patients exhibiting objective
responses.