[AS PER AMENDMENT 6/16/97: If a cohort has exactly two patients in the rhIL-12 arm that experience a primary toxicity endpoint, then the next cohort receives study drug at the same dose as the current cohort, but administered only once a week. If a cohort receiving study drug administered once a week has at least two subjects experience a primary toxicity endpoint, then further drug administration in Part A is stopped. Any cohort that receives study drug once a week is the last cohort in Part A; no further dose escalation is performed].