SITC 2020 – second chances for Merck & Co and Oncosec

When the Society of the Immunotherapy of Cancer meeting gets under way next week, in virtual format, of course, it could provide an opportunity to show that Rig1 activation and the delivery of plasmid-based IL-12 are, after all, viable oncology approaches.

Both MK-4621, a Rig1 agonist Merck & Co got through its $115m takeover of Rigontec, and Tavo, Oncosec’s electroporation-delivered IL-12 gene therapy, have disappointed, but they feature among a handful of the meeting’s clinical late-breaking presentations, whose titles have just been announced. Intriguingly, a second Rig1 asset, Curevac’s CV8102, is also among the late-breakers.

CV8102 is an RNA therapeutic that additionally activates TLR7/8, and featured at this year’s Asco conference, showing an underwhelming 9% remission rate as monotherapy in cutaneous melanoma. Of the two patients who responded one was PD-L1 naive, while the other was checkpoint refractory.

The SITC late-breaker should detail its combination with PD-1 blockade, and might involve other cancer types too. CV8102 and MK-4621 are the only Rig1 activators in clinical trials for cancer, according to EvaluatePharma; Spring Bank’s inarigivir is in phase II for hepatitis B.

In an earlier study, presented at Esmo 2018, Merck’s MK-4621 also disappointed, though in fairness it might have been too early for it to have yielded meaningful efficacy data. Like for the already announced SITC abstracts, the contents of the late-breakers will not be unveiled formally until just before the meeting (SITC 2020 – embargo snafu triggers the first movers, October 15, 2020).

The Keynote-695 study of Oncosec’s Tavo, meanwhile, looks specifically at checkpoint-refractory melanoma, but has already disappointed not once but twice.

Oncosec, in common with numerous oncology combo players, is hoping to turn “cold” tumours immunogenic and thus make them amenable to checkpoint blockade. The group calls Keynote-695 a registration-enabled phase IIb study, but despite promise in an early trial it looks like time is running out for Tavo.

Another company aiming to overcome tumour resistance is ENB Therapeutics, and it too is looking at a Keytruda combo.

Among other SITC late-breakers, presentations on Bristol Myers Squibb’s urelumab and Merus/Incyte’s MCLA-145 will be of interest to those following the anti-CD137 approach, where Pfizer’s utomilumab has extensively been studied in various combinations. Little has been disclosed about MCLA-145, the subject of a 2016 tie-up, and its SITC presentation is likely preclinical.

The first preclinical data will also be revealed on Five Prime’s FPA157, which the company says is engineered to eliminate tumour-infiltrating T regulatory cells. Tregs are one mechanism behind tumour resistance, and have attracted deal-making, most recently between Gilead and Jounce over JTX-1811; like FPA157 this is an antibody against CCR8.