Examining Burden of Disease and Access to Care in Adults with X-Linked Hypophosphatemia in Brazil

OBJECTIVES: X-linked hypophosphatemia (XLH) is a rare genetic disorder of phosphate wasting associated with significant disease burden. While the fully human monoclonal anti-FGF23 antibody burosumab has proven efficacy in XLH, a lack of universal access to treatment in adults across the global XLH population continues to be an important issue. The 10-year XLH disease monitoring program (DMP) examines real-world treatment patterns and disease burden in the US, Canada, and Latin America. We explore these factors at baseline in Brazilian adults with XLH to assess the local disease impact on this population.
METHODS: The XLH DMP enrolled patients with XLH in three groups: first, who previously received burosumab in a prior clinical trial; second, began burosumab commercially; and third, burosumab-naïve. Of 481 adult subjects enrolled as of Year 3 of the DMP, 50 (10.4%) are from Brazil. Demographics of adult patients from Brazil including age, sex, BMI, and baseline serum phosphorous levels were generally comparable to the overall population.
RESULTS: Key measures of XLH disease burden were examined in the burosumab-naïve Brazilian adults to assess disease impact and treatment need. The mean Timed Up and Go Test in was slower (13.0s) versus the overall population (11.1s), and 15/45 (33.3%) Brazilian versus 45/149 (30.2%) overall patients reported using an assistive mobility device. The mean WOMAC Pain and Physical Function scores (25.8, 24.7) was similar compared with the overall population (27.4, 27.5). Of retired subjects, 7/9 (77.8%) from Brazil versus 12/24 (50%) overall reported retiring early due to XLH.
CONCLUSIONS: Despite generally comparable measures of XLH disease burden, far fewer Brazilian adults received burosumab (5/50; 10%) versus the overall DMP population (332/481; 69%). This highlights the unmet need for access to adequate treatment for Brazilian adults with XLH, which likely stems from the lack of reimbursement in this country despite marketing authorization of burosumab 5 years ago.