Phase I study to define the safety profile and pharmacokinetic parameters of SGN-35 in patients with relapsed/refractory CD30-positive hematologic malignancies. This is a single-arm, open-label, Phase I dose escalation study designed to define the MTD, PK, immunogenicity and anti-tumor activity of SGN-35 in patients with relapsed/refractory CD30-positive hematologic malignancies.