In the phase II SOLSTICE clinical trial, they tested two treatments for chronic hepatitis D: monotherapy tobebibart every 2 weeks and combination therapy tobebibart plus elebsiran every 4 weeks.[1] Hepatitis D is an HBsAg-dependent satellite virus that rapidly leads to liver fibrosis, cirrhosis, and liver failure, with limited therapeutic options.[1] The primary endpoint at week 24 was a composite response: HDV RNA below the limit of detection or ≥2 log₁₀ IU/mL reduction from baseline and ALT normalization.[1] At week 24, 47% of patients on combination therapy and 70% on monotherapy achieved this response.[1] At week 48, HDV RNA was undetectable in 66% (21 of 32) in the combination group and 48% (16 of 33) in the monotherapy group.[1] Normalization of ALT at week 48 was achieved by 56% (18 of 32) in the combination group and 61% (20 of 33) in monotherapy.[1] A study showed antiviral activity of both approaches in patients with chronic HDV infection.[1]