Trisomy 21 (T21) is the most common human chromosomal disorder, occurring in ~1/700 live births, leading to the condition known as Down syndrome (DS). Importantly, people with DS display widespread immune dysregulation and over half of adults with T21 are affected by one or more autoimmune conditions, including several immune skin conditions. The driving hypothesis for this study is that hyperactivation of interferon (IFN) signaling leads to myriad immune-driven diseases and immunological phenotypes in people with DS, and that pharmacological inhibition of IFN signaling could have multidimensional therapeutic benefits in this population.

This study utilizes Tofacitinib, an FDA-approved drug known to block IFN signaling and several accompanying inflammatory pathways, to reduce IFN signaling in DS and to measure its effects via multidimensional endpoints. Previous studies and current clinical trials indicate that Janus kinase (JAK) inhibitors, such as Tofacitinib, can block inflammatory pathways and may have beneficial effects on immune skin conditions. Further, inhibition of chronically active IFN signaling in DS with Tofacitinib may attenuate other core drivers of immune dysregulation, leading to improvements in other immune diseases and conditions common to DS that are potentially driven by inflammation, such as cognitive deficits. Investigators will test these hypotheses using a battery of immune and molecular assessments, as well as cognitive testing and quality of life measures. This clinical trial evaluates adult participants with DS during eight study visits over an approximate five month period.

Specific Aims:

1. To define the safety profile of JAK inhibition in people with DS,
2. To determine the impact of JAK inhibition on the immune dysregulation caused by trisomy 21,
3. To define the impact of JAK inhibition on immune skin conditions in DS, and
4. To characterize the impact of JAK inhibition on cognition and quality of life in DS.