Asco-GU 2019 – Nektar gets that sinking feeling again

Last year Nektar saw an initially impressive-looking remission rate in melanoma melt away as more subjects were treated, and yesterday the story was repeated – this time in bladder cancer. At Asco 2018 the group had reported a 60% response rate in the first 10 front-line urothelial carcinoma subjects in the Pivot-02 trial treated with NKTR-214 combined with Bristol-Myers Squibb’s Opdivo. But Pivot-02’s abstract at the upcoming Asco-Genitourinary Cancers symposium, unveiled yesterday, showed that a further 13 evaluable urothelial carcinoma patients yielded just five more remissions, pushing the total rate down to 48%. There are still more patients to recruit; Evercore ISI noted that the threshold for taking the combo forward was 45%. In Pivot-02’s melanoma cohort a 64% remission rate fell to 53% as more subjects were treated (SITC 2018 – Nektar’s big reveal falls flat, November 11, 2018). NKTR-214, a CD122-biased agonist of the IL-2 pathway, represents one test of the cytokine approach to broadening remissions to checkpoint blockade, something still supported by the fact that five of the current 11 urothelial carcinoma responders were PD-L1 negative. As Nektar stock dropped 8% this morning investors were also left to mull NKTR-214’s new, virtually unpronounceable generic name: bempegaldesleukin.