A Placebo-controlled Study of PF-06473871 (Anti-Connective Tissue Growth Factor Antisense Oligonucleotide) in Reducing Hypertrophic Skin Scarring

BACKGROUND: Connective tissue growth factor (CTGF) is a matricellular protein that plays a key role in wound healing and scar formation. Inhibition of CTGF by a specific antisense oligonucleotide significantly reduced scarring and fibrosis in animal models. This study examined whether an antisense oligonucleotide that inhibits human CTGF expression could reduce the severity of hypertrophic scar formation in patients following surgical revision of preexisting breast scars. METHODS: This study was a 24-week multicenter, randomized, double-blind, within-subject, placebo-controlled phase 2b study evaluating the efficacy and safety of PF-06473871 in 2 regimens of either 3 or 4 intradermal injections (postsurgery weeks 2, 5, 8, and 11) of 5 mg/cm adjacent to the new surgical incision. One hundred subjects with bilateral hypertrophic scars resulting from prior breast surgery were randomized. Efficacy was determined by the Patient and Observer Scar Assessment Scale (POSAS). RESULTS: The Physician/Observer POSAS overall opinion score at (week 24) for the 4-injection regimen demonstrated a statistically significant (P = 0.022) treatment difference from placebo of 0.68, and the treatment difference for the 3-injection regimen was nonsignificant (P = 0.4). Physician evaluation of scar severity at (week 24) with the photo-guide in the 4-injection regimen had a significant reduction (point estimate of treatment difference of 0.43 favoring PF-06473871). The surgical effect was approximately 2.0 at week 24 and was nearly 3 times greater than the treatment effect. Patient evaluations using the POSAS and photo-guide were not significantly improved with either dose regimen. PF-06473871 was generally well tolerated systemically and locally. CONCLUSION: The 4-dose regimen of PF-06473871 provided statistically significant improvement, inhibiting severity of hypertrophic scar formation based on physician assessment. However, the effect of revision surgery alone is significant and may dominate the treatment effect of PF-06473871.