Hookipa halts spending on cytomegalovirus vaccine after seeing phase 2 data

Hookipa Pharma’s hopes of partnering its cytomegalovirus (CMV) vaccine HB-101 have taken a hit, with final phase 2 data showing that giving two doses of the prophylactic prospect was no better at reducing viral infection than placebo in kidney transplant patients.

The Austrian biotech began pulling back from the program late in 2021. At that time, the assessment of interim data from the phase 2 trial and emerging evidence on cancer candidate HB-200 led Hookipa to prioritize its oncology programs and seek partners for HB-101. Sixteen months later, the biotech has final data from the phase 2 CMV vaccine trial—but is yet to find a partner willing to take the program forward.

Hookipa lacks the data to make a clear, compelling case to potential partners, admitting that the “small numbers and lower-than-expected incidence of CMV disease limit conclusion regarding efficacy” in the clinical trial.

Here’s what we know. Investigators administered at least one dose of HB-101 or placebo to 80 people, well down on the 150 participants Hookipa aimed to enroll before the pandemic disrupted the study. In the placebo-controlled, CMV-negative part of the trial, 52 participants received at least two doses. Two doses had no effect on the incidence of CMV infection, syndrome or disease, or the use of antivirals. 

Early data from the trial previously led Hookipa to outline (PDF) plans for dose-finding for a three-dose schedule but only a small number of subjects received that many doses in the phase 2. The proportion of people who developed CMV viremia and needed post-transplant antivirals was lower in the three-dose HB-101 arm than the placebo group, 22.2% versus 37.5%, but the analysis only featured 17 patients.

Faced with the data, Hookipa has decided against continuing to invest in HB-101. The decision continues a pivot away from infectious diseases that has been underway for years. Hookipa still has hepatitis B assets in development in partnership with Gilead but its pipeline is now dominated by immuno-oncology programs. Phase 2 Keytruda combination data on HB-200 are due in the second quarter of 2023.