MD and Eric M. Ruderman

Janus kinase inhibitors (JAKi) are a novel class of oral, targeted small-molecule inhibitors that are increasingly used to treat several different autoimmune conditions. In terms of rheumatologic indications, the FDA first approved tofacitinib (TOF) for use in moderate to severe rheumatoid arthritis (RA) unresponsive to methotrexate therapy. Eleven years later, the indications for JAKi use have expanded to include ulcerative colitis, ankylosing spondylitis, and psoriatic arthritis (PsA), among other diseases. As with any new therapeutic mechanism, there are questions as to how JAKi should be incorporated into the treatment paradigm of PsA. In this article, we briefly review the efficacy and safety data of these agents and discuss our approach to their use in PsA.

Two JAKi are currently FDA approved for the treatment of PsA: tofacitinib (TOF) and upadacitinib (UPA). Other JAKi, such as filgotinib and peficitinib, are only approved outside the United States and will not be discussed here. 

TOF was originally studied in skin psoriasis (PsO) before 2 pivotal studies demonstrated efficacy in PsA. TOF or adalimumab (ADA) were compared with placebo in patients who had failed conventional synthetic disease-modifying antirheumatic drugs (DMARD).¹ ACR20 response was superior with TOF 5 mg twice daily (BID) (50%) and 10 mg BID (61%) vs placebo (33%), and it was comparable to ADA (52%), which was used in this study as an active comparator. The overall rate of adverse events was similar with both doses of TOF when compared with ADA; however, patients taking TOF had numerically more cases of cancer, serious infection, and herpes zoster. 

Another study evaluated TOF compared with placebo in patients with PsA who had an inadequate response to tumor necrosis factor inhibitor (TNFi) therapy.² The study showed an ACR20 response of 50% in patients taking TOF 5 mg BID and 47% in patients taking 10 mg BID, compared with 24% in those taking placebo. Patients who received the 10 mg TOF dose continuously had higher rates of adverse events compared to TOF 5 mg, placebo, and patients who crossed over from placebo to TOF at either dose. In the TOF groups, there were cases of serious infection and herpes zoster, as well as 2 patients with major adverse cardiovascular events (MACE). Following review of these data, the FDA approved only the 5 mg BID dose, and later an 11-mg daily extended-release formulation that was pharmacokinetically similar.

The efficacy for UPA in PsA was shown in 2 pivotal phase 3 trials. SELECT-PsA1 compared UPA at 2 doses, 15 mg and 30 mg daily, vs placebo and vs ADA in patients with biologic DMARD (bDMARD)-naïve PsA.³ This trial demonstrated superiority of UPA in the ACR20 response at both doses (71% and 79%, respectively) compared with placebo (36%). The 15-mg dose of UPA was comparable to ADA (65%), while the 30-mg dose achieved superiority compared to ADA. Secondary outcomes including skin activity, patient-reported symptoms, and inhibition of radiographic progression were also superior in UPA compared with placebo and similar or greater with UPA compared with ADA, depending on the specific outcome.⁴ SELECT-PsA2 compared UPA 15 mg, 30 mg, and placebo in patients with prior incomplete response or intolerance to a bDMARD.⁵ At week 12 of the study, patients taking UPA 15 mg and 30 mg had an ACR20 response of 57% and 64%, respectively, compared with placebo (24%). At week 24, minimal disease activity was achieved by 25% of patients taking UPA 15 mg and 29% of patients taking UPA 30 mg, which was superior to placebo (3%). 

Both studies found a significant increase in infections, including serious infections, at the 30-mg UPA dose compared with the placebo and adalimumab groups. Cytopenia and elevated creatine kinase (CK) level also occurred more frequently in the UPA 30-mg group. Rates of cancer were low overall and comparable between the patients treated with UPA and ADA. Given the higher incidence of adverse events with the 30-mg dose and the relatively similar efficacy, the sponsor elected to submit only the lower dose to the FDA for approval.

In the last few years, concerns for safety with JAKi use grew after the publication of data from the ORAL SURVEILLANCE trial, an FDA-mandated, post-approval safety study of TOF in RA. In this trial, patients with active RA over 50 years of age and with at least 1 additional cardiovascular risk factor were randomized to TOF at 1 of 2 doses, 5 mg or 10 mg BID, or a TNFi.⁶ This trial was designed as a noninferiority study, and TOF did not meet the noninferiority threshold compared to TNFi, with hazard ratios of 1.33 and 1.48 for MACE and malignancy, respectively. The results of this trial prompted the FDA to add a black box warning to the label for all JAKi, pointing out the risk of malignancy and MACE, as well as infection, mortality, and thrombosis. 

In the ORAL SURVEILLANCE trial, the increased risk of MACE and malignancy was primarily seen in the study patients with high risk for a cardiovascular event. To address the question of whether a similar risk profile exists when using JAKi to treat PsA, or whether this is a disease-specific process related to RA, a post hoc analysis of 3 PsA trials and 7 PsO trials of patients treated with TOF was conducted.⁷ The analysis found that patients with a history of atherosclerotic cardiovascular disease (ASCVD) or metabolic syndrome, or patients at high risk for ASCVD (score > 20%) had increased incidence rates of MACE compared with those with low risk scores for ASCVD. Interestingly, as in RA, increased incidence rates of malignancy were seen in patients with preexisting or at high risk for ASCVD.

While the FDA recommends JAKi use in patients who have failed or are inappropriate for treatment with a TNFi, we would consider the use of JAKi for first-line therapy in PsA on an individual basis. One advantage of JAKi is their efficacy across multiple PsA domains, including peripheral arthritis, axial disease, enthesitis, dactylitis, and skin disease (although the approved dose of TOF was not statistically effective for PsO in the pivotal trials). Based on this efficacy, we believe that patients with overlapping, multifaceted disease may benefit the most from these medications. Patient risk factors and comorbidities are a prominent consideration in our use of JAKi to ensure safety, as the risk for MACE and malignancy is informed partly by baseline cardiovascular status. In younger patients without cardiovascular risk factors, JAKi may be a strong candidate for first-line therapy, particularly in patients averse to subcutaneous or intravenous therapy. We do counsel all patients on the increased risk of infection, and we do recommend inactivated herpes zoster vaccination in previously unvaccinated patients planning to start JAKi therapy. 

On the horizon are the development of novel, oral agents targeting tyrosine kinase 2 (TYK2), which is a member of the JAK family of signaling proteins. In fact, the TYK2 inhibitor deucravacitinib was approved by the FDA in 2022 for the treatment of PsO. TYK2 inhibitors appear to have the advantage of a more selective mechanism of action, with fewer off-target effects. There were fewer adverse events in the deucravacitinib trials, which led to its prompt PsO authorization, and the FDA approval for the drug did not include the same black box warning that appears in the label for other JAKi.⁸ A phase 2 study showed early promise for the efficacy and safety of deucravacitinib in PsA.⁹ Further investigation will be needed to better understand the role of deucravacitinib and other TYK2 inhibitors being developed for the treatment of PsA. In the meantime, JAKi continue to be a prominent consideration for first-line PsA therapy in a carefully selected patient population. 

Janus kinase inhibitors (JAKi) are a novel class of oral, targeted small-molecule inhibitors that are increasingly used to treat several different autoimmune conditions. In terms of rheumatologic indications, the FDA first approved tofacitinib (TOF) for use in moderate to severe rheumatoid arthritis (RA) unresponsive to methotrexate therapy. Eleven years later, the indications for JAKi use have expanded to include ulcerative colitis, ankylosing spondylitis, and psoriatic arthritis (PsA), among other diseases. As with any new therapeutic mechanism, there are questions as to how JAKi should be incorporated into the treatment paradigm of PsA. In this article, we briefly review the efficacy and safety data of these agents and discuss our approach to their use in PsA.

Two JAKi are currently FDA approved for the treatment of PsA: tofacitinib (TOF) and upadacitinib (UPA). Other JAKi, such as filgotinib and peficitinib, are only approved outside the United States and will not be discussed here. 

TOF was originally studied in skin psoriasis (PsO) before 2 pivotal studies demonstrated efficacy in PsA. TOF or adalimumab (ADA) were compared with placebo in patients who had failed conventional synthetic disease-modifying antirheumatic drugs (DMARD).¹ ACR20 response was superior with TOF 5 mg twice daily (BID) (50%) and 10 mg BID (61%) vs placebo (33%), and it was comparable to ADA (52%), which was used in this study as an active comparator. The overall rate of adverse events was similar with both doses of TOF when compared with ADA; however, patients taking TOF had numerically more cases of cancer, serious infection, and herpes zoster. 

Another study evaluated TOF compared with placebo in patients with PsA who had an inadequate response to tumor necrosis factor inhibitor (TNFi) therapy.² The study showed an ACR20 response of 50% in patients taking TOF 5 mg BID and 47% in patients taking 10 mg BID, compared with 24% in those taking placebo. Patients who received the 10 mg TOF dose continuously had higher rates of adverse events compared to TOF 5 mg, placebo, and patients who crossed over from placebo to TOF at either dose. In the TOF groups, there were cases of serious infection and herpes zoster, as well as 2 patients with major adverse cardiovascular events (MACE). Following review of these data, the FDA approved only the 5 mg BID dose, and later an 11-mg daily extended-release formulation that was pharmacokinetically similar.

The efficacy for UPA in PsA was shown in 2 pivotal phase 3 trials. SELECT-PsA1 compared UPA at 2 doses, 15 mg and 30 mg daily, vs placebo and vs ADA in patients with biologic DMARD (bDMARD)-naïve PsA.³ This trial demonstrated superiority of UPA in the ACR20 response at both doses (71% and 79%, respectively) compared with placebo (36%). The 15-mg dose of UPA was comparable to ADA (65%), while the 30-mg dose achieved superiority compared to ADA. Secondary outcomes including skin activity, patient-reported symptoms, and inhibition of radiographic progression were also superior in UPA compared with placebo and similar or greater with UPA compared with ADA, depending on the specific outcome.⁴ SELECT-PsA2 compared UPA 15 mg, 30 mg, and placebo in patients with prior incomplete response or intolerance to a bDMARD.⁵ At week 12 of the study, patients taking UPA 15 mg and 30 mg had an ACR20 response of 57% and 64%, respectively, compared with placebo (24%). At week 24, minimal disease activity was achieved by 25% of patients taking UPA 15 mg and 29% of patients taking UPA 30 mg, which was superior to placebo (3%). 

Both studies found a significant increase in infections, including serious infections, at the 30-mg UPA dose compared with the placebo and adalimumab groups. Cytopenia and elevated creatine kinase (CK) level also occurred more frequently in the UPA 30-mg group. Rates of cancer were low overall and comparable between the patients treated with UPA and ADA. Given the higher incidence of adverse events with the 30-mg dose and the relatively similar efficacy, the sponsor elected to submit only the lower dose to the FDA for approval.

In the last few years, concerns for safety with JAKi use grew after the publication of data from the ORAL SURVEILLANCE trial, an FDA-mandated, post-approval safety study of TOF in RA. In this trial, patients with active RA over 50 years of age and with at least 1 additional cardiovascular risk factor were randomized to TOF at 1 of 2 doses, 5 mg or 10 mg BID, or a TNFi.⁶ This trial was designed as a noninferiority study, and TOF did not meet the noninferiority threshold compared to TNFi, with hazard ratios of 1.33 and 1.48 for MACE and malignancy, respectively. The results of this trial prompted the FDA to add a black box warning to the label for all JAKi, pointing out the risk of malignancy and MACE, as well as infection, mortality, and thrombosis. 

In the ORAL SURVEILLANCE trial, the increased risk of MACE and malignancy was primarily seen in the study patients with high risk for a cardiovascular event. To address the question of whether a similar risk profile exists when using JAKi to treat PsA, or whether this is a disease-specific process related to RA, a post hoc analysis of 3 PsA trials and 7 PsO trials of patients treated with TOF was conducted.⁷ The analysis found that patients with a history of atherosclerotic cardiovascular disease (ASCVD) or metabolic syndrome, or patients at high risk for ASCVD (score > 20%) had increased incidence rates of MACE compared with those with low risk scores for ASCVD. Interestingly, as in RA, increased incidence rates of malignancy were seen in patients with preexisting or at high risk for ASCVD.

While the FDA recommends JAKi use in patients who have failed or are inappropriate for treatment with a TNFi, we would consider the use of JAKi for first-line therapy in PsA on an individual basis. One advantage of JAKi is their efficacy across multiple PsA domains, including peripheral arthritis, axial disease, enthesitis, dactylitis, and skin disease (although the approved dose of TOF was not statistically effective for PsO in the pivotal trials). Based on this efficacy, we believe that patients with overlapping, multifaceted disease may benefit the most from these medications. Patient risk factors and comorbidities are a prominent consideration in our use of JAKi to ensure safety, as the risk for MACE and malignancy is informed partly by baseline cardiovascular status. In younger patients without cardiovascular risk factors, JAKi may be a strong candidate for first-line therapy, particularly in patients averse to subcutaneous or intravenous therapy. We do counsel all patients on the increased risk of infection, and we do recommend inactivated herpes zoster vaccination in previously unvaccinated patients planning to start JAKi therapy. 

On the horizon are the development of novel, oral agents targeting tyrosine kinase 2 (TYK2), which is a member of the JAK family of signaling proteins. In fact, the TYK2 inhibitor deucravacitinib was approved by the FDA in 2022 for the treatment of PsO. TYK2 inhibitors appear to have the advantage of a more selective mechanism of action, with fewer off-target effects. There were fewer adverse events in the deucravacitinib trials, which led to its prompt PsO authorization, and the FDA approval for the drug did not include the same black box warning that appears in the label for other JAKi.⁸ A phase 2 study showed early promise for the efficacy and safety of deucravacitinib in PsA.⁹ Further investigation will be needed to better understand the role of deucravacitinib and other TYK2 inhibitors being developed for the treatment of PsA. In the meantime, JAKi continue to be a prominent consideration for first-line PsA therapy in a carefully selected patient population. 

Janus kinase inhibitors (JAKi) are a novel class of oral, targeted small-molecule inhibitors that are increasingly used to treat several different autoimmune conditions. In terms of rheumatologic indications, the FDA first approved tofacitinib (TOF) for use in moderate to severe rheumatoid arthritis (RA) unresponsive to methotrexate therapy. Eleven years later, the indications for JAKi use have expanded to include ulcerative colitis, ankylosing spondylitis, and psoriatic arthritis (PsA), among other diseases. As with any new therapeutic mechanism, there are questions as to how JAKi should be incorporated into the treatment paradigm of PsA. In this article, we briefly review the efficacy and safety data of these agents and discuss our approach to their use in PsA.

Two JAKi are currently FDA approved for the treatment of PsA: tofacitinib (TOF) and upadacitinib (UPA). Other JAKi, such as filgotinib and peficitinib, are only approved outside the United States and will not be discussed here. 

TOF was originally studied in skin psoriasis (PsO) before 2 pivotal studies demonstrated efficacy in PsA. TOF or adalimumab (ADA) were compared with placebo in patients who had failed conventional synthetic disease-modifying antirheumatic drugs (DMARD).¹ ACR20 response was superior with TOF 5 mg twice daily (BID) (50%) and 10 mg BID (61%) vs placebo (33%), and it was comparable to ADA (52%), which was used in this study as an active comparator. The overall rate of adverse events was similar with both doses of TOF when compared with ADA; however, patients taking TOF had numerically more cases of cancer, serious infection, and herpes zoster. 

Another study evaluated TOF compared with placebo in patients with PsA who had an inadequate response to tumor necrosis factor inhibitor (TNFi) therapy.² The study showed an ACR20 response of 50% in patients taking TOF 5 mg BID and 47% in patients taking 10 mg BID, compared with 24% in those taking placebo. Patients who received the 10 mg TOF dose continuously had higher rates of adverse events compared to TOF 5 mg, placebo, and patients who crossed over from placebo to TOF at either dose. In the TOF groups, there were cases of serious infection and herpes zoster, as well as 2 patients with major adverse cardiovascular events (MACE). Following review of these data, the FDA approved only the 5 mg BID dose, and later an 11-mg daily extended-release formulation that was pharmacokinetically similar.

The efficacy for UPA in PsA was shown in 2 pivotal phase 3 trials. SELECT-PsA1 compared UPA at 2 doses, 15 mg and 30 mg daily, vs placebo and vs ADA in patients with biologic DMARD (bDMARD)-naïve PsA.³ This trial demonstrated superiority of UPA in the ACR20 response at both doses (71% and 79%, respectively) compared with placebo (36%). The 15-mg dose of UPA was comparable to ADA (65%), while the 30-mg dose achieved superiority compared to ADA. Secondary outcomes including skin activity, patient-reported symptoms, and inhibition of radiographic progression were also superior in UPA compared with placebo and similar or greater with UPA compared with ADA, depending on the specific outcome.⁴ SELECT-PsA2 compared UPA 15 mg, 30 mg, and placebo in patients with prior incomplete response or intolerance to a bDMARD.⁵ At week 12 of the study, patients taking UPA 15 mg and 30 mg had an ACR20 response of 57% and 64%, respectively, compared with placebo (24%). At week 24, minimal disease activity was achieved by 25% of patients taking UPA 15 mg and 29% of patients taking UPA 30 mg, which was superior to placebo (3%). 

Both studies found a significant increase in infections, including serious infections, at the 30-mg UPA dose compared with the placebo and adalimumab groups. Cytopenia and elevated creatine kinase (CK) level also occurred more frequently in the UPA 30-mg group. Rates of cancer were low overall and comparable between the patients treated with UPA and ADA. Given the higher incidence of adverse events with the 30-mg dose and the relatively similar efficacy, the sponsor elected to submit only the lower dose to the FDA for approval.

In the last few years, concerns for safety with JAKi use grew after the publication of data from the ORAL SURVEILLANCE trial, an FDA-mandated, post-approval safety study of TOF in RA. In this trial, patients with active RA over 50 years of age and with at least 1 additional cardiovascular risk factor were randomized to TOF at 1 of 2 doses, 5 mg or 10 mg BID, or a TNFi.⁶ This trial was designed as a noninferiority study, and TOF did not meet the noninferiority threshold compared to TNFi, with hazard ratios of 1.33 and 1.48 for MACE and malignancy, respectively. The results of this trial prompted the FDA to add a black box warning to the label for all JAKi, pointing out the risk of malignancy and MACE, as well as infection, mortality, and thrombosis. 

In the ORAL SURVEILLANCE trial, the increased risk of MACE and malignancy was primarily seen in the study patients with high risk for a cardiovascular event. To address the question of whether a similar risk profile exists when using JAKi to treat PsA, or whether this is a disease-specific process related to RA, a post hoc analysis of 3 PsA trials and 7 PsO trials of patients treated with TOF was conducted.⁷ The analysis found that patients with a history of atherosclerotic cardiovascular disease (ASCVD) or metabolic syndrome, or patients at high risk for ASCVD (score > 20%) had increased incidence rates of MACE compared with those with low risk scores for ASCVD. Interestingly, as in RA, increased incidence rates of malignancy were seen in patients with preexisting or at high risk for ASCVD.

While the FDA recommends JAKi use in patients who have failed or are inappropriate for treatment with a TNFi, we would consider the use of JAKi for first-line therapy in PsA on an individual basis. One advantage of JAKi is their efficacy across multiple PsA domains, including peripheral arthritis, axial disease, enthesitis, dactylitis, and skin disease (although the approved dose of TOF was not statistically effective for PsO in the pivotal trials). Based on this efficacy, we believe that patients with overlapping, multifaceted disease may benefit the most from these medications. Patient risk factors and comorbidities are a prominent consideration in our use of JAKi to ensure safety, as the risk for MACE and malignancy is informed partly by baseline cardiovascular status. In younger patients without cardiovascular risk factors, JAKi may be a strong candidate for first-line therapy, particularly in patients averse to subcutaneous or intravenous therapy. We do counsel all patients on the increased risk of infection, and we do recommend inactivated herpes zoster vaccination in previously unvaccinated patients planning to start JAKi therapy. 

On the horizon are the development of novel, oral agents targeting tyrosine kinase 2 (TYK2), which is a member of the JAK family of signaling proteins. In fact, the TYK2 inhibitor deucravacitinib was approved by the FDA in 2022 for the treatment of PsO. TYK2 inhibitors appear to have the advantage of a more selective mechanism of action, with fewer off-target effects. There were fewer adverse events in the deucravacitinib trials, which led to its prompt PsO authorization, and the FDA approval for the drug did not include the same black box warning that appears in the label for other JAKi.⁸ A phase 2 study showed early promise for the efficacy and safety of deucravacitinib in PsA.⁹ Further investigation will be needed to better understand the role of deucravacitinib and other TYK2 inhibitors being developed for the treatment of PsA. In the meantime, JAKi continue to be a prominent consideration for first-line PsA therapy in a carefully selected patient population.