OncoGel is a novel depot formulation of paclitaxel designed for intralesional injection with a sustained paclitaxel delivery over approximately 6 weeks from a single administration. This phase 1 study was designed to characterize the toxicity, pharmacokinetics and preliminary antitumor activity associated with OncoGel administered directly into solid tumors. OncoGel was injected into 18 superficially accessible advanced solid cancerous lesions among 16 adult patients for whom no curative therapy was available. Four dose cohorts were evaluated, ranging from 0.06 to 2.0 mg paclitaxel/cm3 tumor volume. OncoGel injections were generally well tolerated. There was one report of grade 3 injection site pain for a patient in the 0.25 mg paclitaxel/cm3 tumor volume dose cohort. Other adverse events considered related to the study drug included mild to moderate local responses to the injection itself. Systemic levels of paclitaxel were detectable only in 3.3% of the samples analyzed (range: 0.53-0.71 ng/ml). For the 14 patients evaluable for disease progression, stable disease was noted among six patients and progressive disease among eight patients. Although the maximum tolerated dose was not identified, the planned maximum dose was administered in the study. OncoGel delivered intralesionally at doses up to 2.0 mg paclitaxel/cm3 tumor volume was well tolerated and paclitaxel remained localized at the injection site, confirming design principles to minimize systemic exposure. Therefore, localized paclitaxel administration using OncoGel merits continued clinical development.