First author of the 1966 report of bleomycin A and B
Hamao Umezawa
First author of the 1966 report 'New antibiotics, bleomycin A and B'. A 2015 textbook chapter says he found the anticancer activity of bleomycin in 1962 while screening culture filtrates of Streptomyces verticillus, and that the findings were published in 1966; a 2009 review says bleomycin was first reported by Umezawa and colleagues in 1966.
Sources
Umezawa H, Maeda K, Takeuchi T, Okami Y. New antibiotics, bleomycin A and B. J Antibiot (Tokyo). 1966;19(5):200-9.
Demain AL, Sanchez S. Microbial drug discovery: 80 years of progress. J Antibiot (Tokyo). 2009;62(1):5-16.
Weber GF. Drugs that Suppress Proliferation (section: DNA Damaging Drugs). In: Molecular Therapies of Cancer. Cham: Springer International Publishing; 2015. p. 113-162. doi:10.1007/978-3-319-13278-5_3.