CHICAGO — Hiroyuki Okuzawa holds an enviable position. The veteran Daiichi Sankyo executive took over as the Japanese drugmaker’s new CEO two months ago and inherited a company whose cancer medicines have, over the past half-decade, won it three of the pharmaceutical industry’s largest licensing deals.

One of those medicines, the antibody-drug conjugate Enhertu, again took the spotlight at the American Society of Clinical Oncology’s annual meeting here, showing potential to become part of standard therapy for the frontline treatment of advanced breast cancer. It did the same in 2022 and 2024.

Okuzawa can point to Enhertu and four other antibody-drug conjugates Daiichi Sankyo’s developing with AstraZeneca and Merck & Co. as proof of the strength of its research laboratories. By 2030, the company plans to have these five “ADCs” approved across more than 30 tumor types, which would allow it to treat nearly 400,000 cancer patients each year.

“We’d like to become one of the most important players in oncology,” said Okuzawa, noting aspirations to crack the top 10 companies by cancer drug sales. “Our senior leaders are now talking about not only top 10, but maybe top 5. We’re very much confident in our ADCs.”

But, current success notwithstanding, the task ahead of Okuzawa is among the most difficult in corporate management. Daiichi Sankyo has one hit drug platform; he must figure out what comes next.

“In the coming five years, our growth will be driven by these five programs,” he said in an interview at ASCO. “But at the same time, we would like to establish the next growth driver.” Identifying that driver will be a big part of the company’s next five-year plan, which it will launch for the fiscal year beginning next April.

Daiichi Sankyo’s current ADCs are built around a technology known as DXd that the company’s scientists have fine-tuned since inventing it 15 years ago. It is the backbone for Enhertu, as well as the recently approved breast cancer medicine Datroway and three other ADCs that remain experimental.

ADCs like these contain three main components: a targeting antibody, a cancer-killing toxin and a linking molecule that can tightly hold onto the drug’s payload while it’s transiting through the body, but then release it upon arriving at the tumor. The concept is simple, but the details make the difference in balancing efficacy with safety.

Both AstraZeneca and Merck are convinced Daiichi Sankyo has struck the right balance. The former company gave Daiichi Sankyo $1.35 billion in 2019 to license rights to what became Enhertu and then one year later paid another $1 billion upfront for the drug the two companies now sell as Datroway. Then, in 2023, Merck bought rights to the three experimental ADCs for $5.5 billion in payments spread over two years.

Daiichi Sankyo’s next big thing might end up being more ADCs. Okuzawa highlighted two as particularly promising. The first, dubbed DS-3939, combines an antibody licensed from Glycotope with the DXd backbone. It could be an opportunity for Daiichi Sankyo to take on independently, said Okuzawa. The other, DS-9606, uses a new payload technology Daiichi Sankyo hopes will yield other medicines in much the same way DXd has.

Yet Okuzawa, who has been at Daiichi Sankyo since 1986 and previously held several senior leadership positions, noted that the company’s research may take it in new directions, too. “There are a lot of opportunities in the ADC space. On the other hand, [our scientists] are also pursuing discovery research outside of ADCs,” he said. “We have rich ideas for new modalities.”

In the meantime, Daiichi Sankyo needs to execute on the partnerships it already has in place with AstraZeneca and Merck. Combined, those deals promise up to $27 billion in conditional fees due upon Daiichi Sankyo’s medicines reaching certain regulatory and sales milestones. While some of those payments have already been made, the bulk remains unrealized.