• AbbVie has expanded its oncology pipeline with the acquisition of Mavupharma, a privately held biotech targeting cancer through an immune pathway called STING. The companies did not disclose the terms of the transaction when announcing the deal Monday.
• Mavupharma had been nearing the start of clinical trials later this year for its lead candidate, an oral agent that it believes will have fewer side effects than the injectable STING stimulators that have so far been tested in the clinic.
• AbbVie’s record in developing cancer drugs is spotty, with clinical setbacks for Rova-T and ABT-414 in the past eight months. Immuno-oncology remains an attractive sector for biopharma companies, though, following the successes of Merck & Co.’s Keytruda and Bristol-Myers Squibb’s Opdivo.

Fresh off the biggest acquisition in its history, a $63 billion deal for Allergan, AbbVie has added a small transaction with longer-term implications.

Buying Mavupharma brings in a small-molecule immuno-oncology drug that is nearing first-in-human trials later this year. MAVU-104 is an inhibitor of ENPP1, an enzyme that turns off an immune pathway called STING, or stimulator of interferon gene complex.

STING activates immune cells that can attack tumors. Experimental STING activators are viewed as potential complements to Keytruda (pembrolizumab) and Opdivo (nivolumab), which turn off cancer’s mechanisms for escaping immune response.

Mavupharma was hoping it would be able to differentiate MAVU-104 in two ways. The first is oral delivery, because clinical-stage projects like ADU-S100 from Aduro and Novartis must be injected directly into the tumor. Even GlaxoSmithKline’s GSK3745417 requires intravenous infusion.

The second difference is that by acting upstream from STING, MAVU-104 could provide a “tunable” immune response. Direct STING activators can stimulate pro-inflammatory proteins that can cause unwanted side effects, according to Mavupharma.

AbbVie did not say what it paid for Mavuphama, although the price was almost certainly small. Mavupharma completed a $20 million Series A fundraising in late 2017 led by Frazier Healthcare Partners.

In that regard, the Mavupharma deal differs from AbbVie’s most well-known takeout of a privately held oncology company. In 2016, the Illinois-based company paid $5.8 billion for Stemcentrx and its heralded experimental drug Rova-T (rovalpituzumab tesirine). That drug failed, and AbbVie took a $4 billion impairment earlier this year on the transaction.