Background/Purpose: Apremilast (APR), a small molecule inhibitor of phospodiesterase 4 (PDE-4), was recently approved for treating PsA patients in the US. To date, there are no studies directly comparing APR to the current standard of care, MTX. This analysis compared the cost per responder for APR versus MTX and adalimumab (ADA) (a TNF inhibitor) from a US perspective.

Methods: A systematic literature review was performed to extract response rates from clinical trials of approved biologics, MTX, and APR. The selected clinical trials were required to be in the MTX-naïve PsA population and have a placebo arm. A subanalysis of the ADEPT trial, a phase 3 trial comparing ADA with placebo, was conducted among patients who did not receive MTX in the 3 month baseline period. Using Bayesian methods, a network meta-analysis was conducted to indirectly compare the efficacy outcomes between approved therapies for PsA at week 16. Based on the response outcomes relative to placebo, the number needed to treat (NNT) was calculated using the inverse of absolute risk reduction. Cost of treatment was defined as the cost of drug (wholesale acquisition cost) required to treat patients for 16 weeks per labelled dose and cost for placebo was assumed to be zero. The incremental cost per responder was calculated by multiplying the cost of treatment and NNT for each of the therapies.

Results: The MIPA¹ trial for MTX, PALACE 4² for APR and the ADEPT subpopulation for ADA were the only clinical trials that met inclusion criteria. ACR20 was the common clinical outcome among the trials and was reported at week 16 for both ADA in ADEPT and APR in PALACE4, while week 24 results were reported for MTX in MIPA.  In the absence of week 16 efficacy data for MTX, efficacy at week 24 was assumed to be similar at week 16 for this analysis, conservatively. Upon analysis, the NNTs for MTX, APR and ADA were 8.31, 6.69 and 2.63, respectively, and the 16 weeks drug costs were $436, $6,844 and $10,010, respectively. The cost per ACR20 responder was $3,622 for MTX, $45,808 for APR and $26,316 for ADA.

Conclusion: Among MTX-naïve PsA patients, ADA had the lowest NNT compared with MTX and APR at week 16. Compared with MTX and ADA, APR had the highest cost per responder estimates among MTX-naïve PsA patients at week 16.

Reference:

1.       Kingsley GH, Kowalczyk A, Taylor H, et al. A randomized placebo-controlled trial of methotrexate in psoriatic arthritis. Rheumatology. 2012;51:1368-77.

2.       Wells AF, et al. Apremilast in the treatment of DMARD-naïve psoriatic arthritis patients: results of a phase 3 randomized, controlled trial (PALACE 4). Presented at ACR 2013.

**At the upper limit there is no incremental benefit