Illumina CEO Francis deSouza resigned on Sunday following a protracted proxy battle with activist investor Carl Icahn.

Replacing deSouza, who joined the company in 2013, is Charles Dadswell, SVP and general counsel. Dadswell will be helming Illumina in an interim capacity until a permanent replacement is named by the board of directors.

During the search, which is ongoing, deSouza will remain on in an advisory capacity until July 31.

The company thanked deSouza for his leadership and pointed to promising assets in its future.

“Illumina’s technology remains at the forefront of DNA sequencing and has continued to set the pace for the industry. We are confident Illumina can continue to execute on its goals while we conduct and complete a CEO search process,” said Stephen P. MacMillan, chair of the board of Illumina, in a statement. 

For his part, Icahn welcomed the CEO change in a tweet Sunday morning, calling it a “positive occurrence.” 

Illumina’s shares rose during the early morning trading Monday after the resignation was announced.

The abrupt exit for deSouza comes three weeks after he survived a leadership challenge spurred by a months-long feud with Icahn.

The current macroeconomic climate has positioned cash-rich life sciences companies like Illumina to become the apple of activist investors’ eyes.

To that end, $36-billion hedge fund Farallon Capital succeeded earlier this month in its proxy battle to refresh the board at oncology-focused biotech company Exelixis, electing all three of its independent candidates. 

Among the issues at play with Illumina is its $7.1 billion acquisition of cancer test developer Grail in 2021. Both the Federal Trade Commission and European Commission told Illumina to unwind the deal, charging that it was anticompetitive in nature.

In mid-March, Icahn requested the San Diego-based DNA sequencing company appoint three of his nominees to the board of directors. Shortly after that push, Icahn remarked that Illumina should bring back its former CEO Jay Flatley and further criticized the Grail purchase.

At the end of Q1, Illumina urged its shareholders to reject Icahn’s board nominees, alleging that those individuals would “threaten the progress” of its core business. Days later, Illumina challenged the FTC’s order to unwind the Grail deal.

One month later, things heated up in the public feud.

Proxy advisory firm Glass Lewis delivered Icahn a tactical victory, saying deSouza and board chairman John Thompson shouldn’t be reelected to the board of directors. Later that month, shareholders voted and Thompson was ousted while deSouza was reelected as CEO. One of Icahn’s nominees was also appointed to the board.

In addition to leaving the top spot, deSouza is also relinquishing his seat on the board.