Palopegteriparatide in Japanese adults with hypoparathyroidism: 52-week results from the phase 3 PaTHway Japan trial.

PaTHway Japan is an ongoing, phase 3, multicenter, single-arm, open-label trial comprised of a 26-week efficacy period with an extension period through week 182 designed to demonstrate the efficacy, safety, and tolerability of palopegteriparatide in Japanese individuals with hypoparathyroidism. Japanese men and women (≥18 years of age) with hypoparathyroidism of any etiology (≥26 weeks) taking stable doses of active vitamin D were enrolled across five sites in Japan. Once-daily palopegteriparatide was self-administered subcutaneously via a pre-filled pen injector. Titration of palopegteriparatide and conventional therapy was performed according to a protocol-specified algorithm. The main outcomes measures included the proportion of participants at week 26 who achieved albumin-adjusted serum calcium in the normal reference range, independence from active vitamin D, and independence from therapeutic doses of elemental calcium. Thirteen participants were enrolled. Hypoparathyroidism etiology was most commonly idiopathic, followed by postsurgical and genetic causes. After 26 weeks of treatment with palopegteriparatide, 92% (12/13) of participants achieved the primary multi-component endpoint. Of the participants who entered the extension period, 92% (11/12) met the multi-component endpoint at week 52. Adverse events were mild to moderate in severity; none led to discontinuation of palopegteriparatide treatment. These findings in Japanese adults are consistent with results of the pivotal phase 3 and phase 2 North American/European trials and demonstrate the reproducibility of the palopegteriparatide treatment benefit in diverse populations and geographies. Japan Registry of Clinical Trials ID: jRCT2051210058.