Eli Lilly and Company has reported the data from a phase III trial comparing the effects of Forteo (teriparatide [rDNA origin] injection) and risedronate on back pain in postmenopausal women with osteoporotic vertebral fractures. The study showed no difference between Forteo and risedronate on the primary endpoint of at least a 30 per cent reduction in worst back pain from baseline to six months of therapy, as assessed by a numeric rating scale in each treatment group.

However, there were statistically significant differences in favour of Forteo in some exploratory measures, including greater increases in bone mineral density (BMD) and fewer patients with new vertebral fractures. The results of the study are published in the August issue of Osteoporosis International.

“With many available options to treat osteoporosis, this study is important because it compares two established osteoporosis medicines in a direct head-to-head design,” said lead investigator Peyman Hadji, MD, department head, endocrinology, osteoporosis and reproductive medicine at Philipps-University of Marburg.

At six months, more than half of patients in both treatment groups reported a 30 per cent or greater reduction in worst back pain ( Forteo — 59.2 per cent, risedronate — 57.4 per cent; p=0.64). (A 30 per cent or greater reduction is considered a clinically meaningful change.) There were no statistically significant differences between treatments in the secondary and exploratory endpoints of at least a 30 per cent reduction in worst or average back pain at six, 12 or 18 months; quality of life; disability; days of bed rest; days of disability; and amount of concomitant analgesics used. Significantly fewer patients treated with Forteo experienced a worsening of average back pain between six and 18 months (23.6 per cent vs. 30.6 per cent of risedronate-treated patients; p=0.04). Significantly fewer patients treated with Forteo had one or more new vertebral fractures at 18 months (4.4 per cent vs. 9.4 per cent of risedronate-treated patients; p=0.01). Among patients with new vertebral fractures, those treated with Forteo had overall less severe new fractures compared to those who received risedronate, as measured by spine radiograph (p=0.04). There was no significant difference between treatment groups in the number of patients with new non-vertebral fractures.

Additional findings included: patients treated with Forteo had a greater average increase in BMD at the lumbar spine (+7.80 +/- 0.5 per cent vs. +2.63 +/- 0.5 per cent in risedronate-treated patients; p < 0.001) and at the femoral neck (+2.11 +/- 0.4 percent vs. +0.77 +/- 0.4 percent, respectively; p=0.02) at 18 months and patients in the Forteo group had significantly less height loss compared to the risedronate group at 18 months (0.44 centimeters vs. 0.70 centimeters; p < 0.05).

“The study provides additional information regarding the use of Forteo in patients who are considered at high risk for osteoporotic fractures,” said Bruce Mitlak, MD, Distinguished Medical Fellow, Bone Muscle and Joint Platform, Eli Lilly and Company. "The results may help guide healthcare professionals in treating severe osteoporosis."

In the study, the overall safety profile was consistent with the known Forteo safety profile seen in this patient population. The overall incidence of serious adverse events, treatment-emergent adverse events and adverse events leading to discontinuation were similar between the FORTEO and risedronate treatment groups. There were nine deaths in the study (four in the Forteo group and five in the risedronate group), but none of the deaths were considered related to treatment.

Forteo is used in both men and postmenopausal women with osteoporosis who are at high risk for having broken bones (fractures). Forteo is used in both men and women with osteoporosis due to use of glucocorticoid medicines, such as prednisone, for several months, who are at high risk for having broken bones (fractures). Forteo can be used by people who have had a fracture related to osteoporosis, or who have several risk factors for fracture, or who cannot use other osteoporosis treatments.

During the drug testing process, the medicine in Forteo caused some rats to develop osteosarcoma, which, in humans, is a serious but rare bone cancer. Osteosarcoma has been reported rarely in people who took FORTEO, and it is unknown if people who take Forteo have a higher chance of getting the disease. Before patients take Forteo, patients should tell their healthcare provider if they have Paget's disease of bone, are a child or young adult whose bones are still growing or have had radiation therapy.

"The Effect of Teriparatide Compared with Risedronate on Reduction of Back Pain in Postmenopausal Women with Osteoporotic Vertebral Fractures" was a phase III, prospective, randomized, double-blind, double-dummy, active-controlled, 18-month trial involving 710 postmenopausal women with at least one moderate or severe vertebral fracture thought to be the cause of back pain. The primary objective was to compare the efficacy of Forteo (20 micrograms/day) and risedronate (35 milligrams/week) based on the proportion of women who reported a 30 percent or greater reduction in worst back pain severity, as assessed by an 11-point numeric rating scale (0=no pain; 10=severe pain), from baseline to six months of therapy. Pre-specified secondary and exploratory outcomes included assessments of average and worst back pain at additional time points, the mean change in disability as assessed by the Roland Disability Questionnaire, the mean change in quality of life as assessed by Quality of Life Questionnaire of the European Foundation for Osteoporosis (QUALEFFO), change in BMD, incidence of fractures, and safety.

During the drug testing process, the medicine in Forteo caused some rats to develop a bone cancer called osteosarcoma. In people, osteosarcoma is a serious but rare cancer. Osteosarcoma has been reported rarely in people who took Forteo. It is not known if people who take Forteo have a higher chance of getting osteosarcoma. Before you take Forteo, you should tell your healthcare provider if you have Paget's disease of bone, are a child or young adult whose bones are still growing, or have had radiation therapy.