Evaluation of clinical trials done for orphan drugs versus nonorphan drugs in infectious diseasesan eleven year analysis [2010-2020].

Background: The 1983 US Orphan Drug Act provided impetus for the development of new therapies for rare diseases. Several studies focused on the number of orphan designations over time. However, very few focused on clinical trials that lead to their approval, particularly for infectious diseases.

Materials and methods: All new drug approvals (orphan and non-orphan) by the US Food and Drug Administration (FDA) from January 2010 to December 31, 2020, were identified and details of approvals were taken from the US-FDA labels and summary reports for each drug. The pivotal trials for each were characterized based on their design. We tested the association of the type of drug approval with respect to the characteristics of trial using Chi-square test and generated crude odds ratios with 95% confidence intervals.

Results: From the total 1122 drugs approved, 84 were for infectious diseases, of which 18 were orphan drugs and 66 were nonorphan. A total of 35 pivotal trials supported 18 orphan drug approvals, while 115 pivotal trials supported 66 nonorphan drugs. The median number of participants enrolled/trial for orphan drugs was 89, while for nonorphan drugs, it was 452 (P < 0.0001). Blinding was done for 13/35 (37%) orphan drugs versus 69/115 (60%) nonorphan drugs (P = 0.029); randomization was done for 15/35 (42%) orphan drugs versus 100/115 (87%) nonorphan drugs (P < 0.0001) and 20/35 (57%) of the orphan drugs got approval in phase II versus 8/115 (6%) of nonorphan drugs (P < 0.00001).

Conclusion: A significant number of orphan drugs get approval based on early phase, nonrandomized, and unblinded with a smaller sample size as compared to nonorphan drugs.