SAN DIEGO, June 5, 2015 /PRNewswire/ — Halozyme Therapeutics, Inc. (NASDAQ: HALO), an oncology biotech company, today announced its chief financial officer David Ramsay will retire this summer, and named biotech veteran Laurie Stelzer as his successor. Stelzer will assume CFO duties on June 15 and will work with Ramsay through a transition period. “Since last…