Switch From rhPTH1-84 to TransCon PTH With Individual Dose Adjustment in Adult Hypoparathyroidism-4-Week Results

Replacement therapy with recombinant human PTH (rhPTH1-84) represents a causal treatment for patients with chronic hypoparathyroidism (HypoPT). Recently, palopegteriparatide (TransCon PTH), a novel long-acting drug with slow release of PTH1-34, was approved by the European Medicines Agency and Food and Drug Administration for treatment of HypoPT. To date, no data exist on the treatment switch from rhPTH1-84 to TransCon PTH.

We retrospectively analyzed clinical data from 40 patients with chronic HypoPT during the switch from rhPTH1-84 to TransCon PTH. Independent of the last prior rhPTH1-84 dose, all patients were started on 18 µg of TransCon PTH as recommended by the manufacturer. TransCon PTH dose adjustments, changes in additional medication, and adverse events were documented during the treatment switch.

Within the first month after the treatment switch, 80% (n = 32) of patients needed individual adjustment of their TransCon PTH dose to achieve normocalcemia. Dose reduction (to 9-15 µg) was necessary in 38% (n = 15) and an increase (to 21-27 µg) in 43% (n = 17) of patients. Adjustments occurred predominantly (in 62% cases) according to serum calcium levels, partly dependent on symptoms. The prior applied rhPTH1-84 dose correlated significantly with the adjusted TransCon PTH dose (r = 0.4; P = .01). The treatment change was associated with moderate or mild adverse events in 24/40 patients.

We hereby report the first clinical data on switching treatment from rhPTH1-84 to 18 µg TransCon PTH independent of the prior rhPTH1-84 dose. Our data support discrete adaptation of the starting dose depending on the prior rhPTH1-84 dosage.