Inclusion Criteria:

- 18 years of age or older

- Histological or cytological diagnosis of neoplasm

- No effective standard therapeutic options

- ECOG performance status of 0-2

- ≥ 4 weeks post therapeutic radiation or recovered (or returned to baseline) from any
acute toxicity associated with prior cytotoxic therapy. Patients previously treated
with non-cytotoxic therapy (e.g., EGFR, VGEF, etc.) and who have recovered from or
have controlled drug-associated toxicity are allowed to enter the trial after a
period consisting of 4 half-lives of the agent.

- Negative serum pregnancy test for women of child-bearing potential within one week
prior to treatment with investigational agents (99mTc-EC20 and EC0489)and willingness
to practice contraceptive methods

- Adequate bone marrow reserve, renal and hepatic function

Exclusion Criteria:

- Concurrent malignancies

- Women who are pregnant or breast-feeding

- Evidence of symptomatic brain metastases

- Receiving concomitant anticancer therapy (excluding supportive care)

- Requires palliative radiotherapy at time of study entry

- Requires antifolate therapy for comorbid conditions

- Heart failure characterized as greater than NYHA Class I

- History of myocardial infarct

- Any of the following baseline echocardiogram findings: valvular lesions (stenosis or
insufficiency) characterized as greater than moderate, systolic ventricular
impairment characterized as greater than mild, left ventricular ejection fraction <
55%, any feature of the echocardiogram that would confound interpretation of the
serial echocardiograms required by the protocol