Gilead's CEO is leaving by the end of the year, and the biotech giant still hasn't picked a replacement. Wall Street has a few ideas.

Screenshot via CNBC

Gilead CEO John Milligan

• Gilead CEO John Milligan said in July that he'll step down by the end of the year.
• Four months later, the biotech company still hasn't announced his replacement.
• According to RBC Capital Markets analyst Brian Abrahams, here's who could replace Milligan.

It's been four months since Gilead Sciences CEO John Milligan said he'd be stepping down from the role at the end of the year.

And so far, it's not clear who will pick up the torch after he departs. Gilead is known for its HIV and hepatitis C medications, and in 2017 it acquired drugmaker Kite Pharma, launching it into a cutting-edge area of cancer medicine.

Read more: Here's why Gilead broke its dealmaking hiatus and splurged $12 billion on a cancer treatment

With 2019 fast approaching, RBC Capital Markets biotech analyst Brian Abrahams posited a list of likely candidates for the job.

"Our sense from speaking with investors is that a CEO with a strong history of successful business development would be particularly well received," Abrahams wrote in a note Tuesday.

A spokeswoman for Gilead said there's no update on the search

Here are the likely candidates:

• Jennifer Teubert, Johnson & Johnson's executive vice president and worldwide chairman for pharmaceuticals. Teubert has experience in HIV, infections diseases, cancer, and immunology - all areas of focus for Gilead.
• Pascal Soriot, CEO of AstraZeneca. The Sunday Times reported in November that the pharma giant has begun succession planning for Soriot.
• Emma Walmsley, CEO of GlaxoSmithKline. Walmsley has only been in the role for a little over a year, but Abrahams notes that she, GSK Pharmaceuticals President Luke Miels, or chief strategy officer David Redfern would make good replacements as Gilead CEO because of their experience in HIV.
• Daniel O'Day, CEO of Roche Pharmaceuticals. At the helm of Roche, O'Day has been involved in deals like the $1.9 billion acquisition of Flatiron Health and the $2.4 billion bid for Foundation Medicine.
• Ian Smith, executive vice president and chief operating officer of Vertex Pharmaceuticals. Smith's been at Vertex since 2001.
• Paul Clancy, chief financial officer of Alexion Pharmaceuticals. Clancy stepped into the role in July 2017 after serving as Biogen's CFO for a decade.
• Gilead could also turn to executives with scientific background like Hal Barron, who joined GSK in 2017 as chief scientific officer, long-time Regeneron CSO George Yancopoulos, or Lawrence Blatt, who was formerly the global head of infectious disease and vaccines at J&J.

Gilead could also count on some former executives to step back into the CEO role.

• Bob Hugin, former Celgene CEO. Hugin recently lost a bid for US senator.
• Jeremy Levin, CEO of Ovid Therapeutics. Levin had a short stint as CEO of Teva Pharmaceuticals between 2012 and 2013.
• David Hung, former CEO of Medivation. Hung left the company after Pfizer acquired the cancer drugmaker for $14 billion acquisition. Hung served as CEO of biotech Axovant for 10 months before stepping down in February.
• Chris Viehbacher, former CEO of Sanofi. Viehbacher currently serves as a managing partner at Gurnet Point Capital, a venture fund based in Cambridge, Massachusetts.

Gilead could also choose to promote internally. Should that happen, Abrahams wrote, Laura Hamill, the company's newly hired executive vice president of worldwide commercial operations, could be a good fit.

See also:

• The first female big pharma CEO had the perfect response to a question about women in leadership
• Regeneron's coming late to a group of drugs that's already worth billions - here's why the company thinks it can still compete
• We spoke to the CEO of Roche Pharmaceuticals about how the pharma giant became a deal machine in 2018