Therapeutic and Analytical Evaluation of Ruxolitinib for Vitiligo: A Hybrid Systematic-Narrative Review

Vitiligo is an autoimmune skin disease that causes the loss of melanocytes and leads to white patches on the skin. The main cause is the activation of CD8⁺ T lymphocytes and the inflammatory cytokine IFN-γ 1. Autoreactive T lymphocytes release IFN-γ in affected skin, which is essential for disease progression in mouse models 1. IFN-γ signaling activates JAK/STAT and produces chemokines like CXCL10. This process recruits more T cells and continues the death of melanocytes 1. In fact, higher levels of CXCL10 in the skin are linked to increased disease activity 1. This finding suggests that blocking the IFN-γ-JAK pathway might stop depigmentation 1. A 2025 meta-analysis of 12 randomized controlled trials, involving 2,847 participants, showed that topical JAK inhibitors achieve 2.67 times higher T-VASI50 compared to placebo (RR 2.67, 95% CI 1.24-5.78; p<0.001). This establishes ruxolitinib as a first-line therapy 25. Traditional treatments for vitiligo include topical steroids, calcineurin inhibitors, and narrow-band UVB. These options vary in effectiveness and safety. In cases of generalized vitiligo, a comparative study of phototherapy options found that PUVA and psoralen-NB UVB usually result in better repigmentation than NB UVB alone, showing that phototherapy is a key treatment 1. Small-molecule JAK inhibitors offer targeted immune system modulation. JAK family members (JAK1-3, TYK2) play a role in cytokine receptor signaling, while JAK1 and JAK2 are specifically involved in IFN-γ signaling 13.JAK inhibitors like tofacitinib and ruxolitinib have demonstrated the ability to induce repigmentation in clinical case reports. Additionally, preclinical studies indicate that blocking STAT1/CXCL10 can eliminate vitiligo in mice 13. Therefore, JAK inhibition is a sensible treatment approach for vitiligo.

MATERIALS AND METHODS

This review search was conducted to identify relevant studies conducted on clinical efficacy of JAK inhibitors and the analytical methodology of Ruxolitinib. The primary materials for the review consists of peer- reviewed research articles and clinical trial reports from various electronic databases.

Search Strategy (Jan 2020-Mar 2026): PubMed, Scopus, Cochrane Library, Web of Science using keywords: (ruxolitinib, JAK inhibitor, vitiligo, HPLC, LC-MS, UPLC)

Total records identified: n=1,247

Inclusion Criteria:

• Phase 2-4 RCTs (n≥50 patients)
• Real-world studies (n≥50 patients)
• Systematic reviews/meta-analyses
• Validated analytical methods (ICH Q2 compliant)
• English language, 2020-2026

Exclusion Criteria:

• Case reports/series (n<10)
• Preclinical/animal studies
• Non-validated analytical methods
• Conference abstracts only

Data Extraction: Two reviewers independently extracted efficacy (F-VASI75, T-VASI50), safety (AEs, discontinuations), and analytical parameters (LOD, LOQ, linearity).

Hybrid approach: systematic synthesis of RCTs/meta-analyses + narrative review of mechanisms.

1. 1.  and Rationale for JAK Inhibition
   6. is characterized by a Th1-like autoimmune response, with lesional skin and blood of patients harboring oligoclonal, melanocyte-specific CD8+ T cells that secrete IFN-γ ¹. In addition to directly killing melanocytes, IFN-γ induces keratinocytes to produce CXCL9/CXCL10, which then amplify the recruitment of T cells to skin ¹. Accordingly, CXCL10 is increased in the serum and skin lesions of vitiligo patients which may be blocked experimentally (e.g. STAT1) to abrogate depigmentation in mouse models ¹.. Conceptual reviews ¹⁷ as well as translational work ¹ on the IFN-Γ/CXCL10 axis has posited this mechanism as a ‘fuel’ of vitiligo and suggested that IFN-Γ signalling and/or CXCL10 blockade may prevent t-cell-mediated loss of melanocytes and present a mechanistic rationale for JAK inhibitors ¹⁸. Clinical biomarker studies demonstrate that both serum levels and tissue concentrations of CXCL10 correlate with leukocytic infiltrate ¹⁸. The short disease duration and elevated inflammation in vitiligo patients and that CXCL10 levels reduce in concert with repigmentation in response to PUVA, NB-UVB or systemic steroid therapy ¹⁸. Suspension-blister sampling has revealed that lesional skin of active vitiligo has more CD8+ T-cells and higher concentrations of CXCL9 than non-lesional skin and that the infiltrating T-cell population is predominantly CXCR3+ ^1,18. With the central role for IFN-γ/JAK signalling, therapeutic inhibition of JAK appears likely to prevent or break the vicious circle of inflammation and loss of melanocyte. The retrospective reports demonstrate both oral and topical JAK inhibition can promote repigmentation. For example, two patients with vitiligo were treated off-label with JAK inhibitors (tofacitinib or ruxolitinib) and demonstrated significant repigmentation ¹³. Therefore, inhibition of JAK1/2 (by ruxolitinib) or JAK1/3 (tofacitinib) is considered rational by mechanism.
   19562827556.  Efficacy and Safety of JAK Inhibitors
                2513349669471318.  
                6042735620. : Ruxolitinib cream (1.5%) is the first FDA approved targeted therapy for non‐segmental vitiligo. TRuE‑V1/V2 phase 3 (n=674): 29.9% F-VASI75 versus 7.6% vehicle at week 52; were superior across Fitzpatrick types ²⁰.LTE extension (n=323): 50.3% of those on continuous ruxolitinib, achieved F-VASI75 at week 52 (vs 28.2% of those ‘late switched’) 43–66% of those on continuous ruxolitinib thereafter continued through week 104 across all phototypes ¹⁹. In a real-world study (n=287 NSV patients), 52.3% of the patients achieved F-VASI50 response after 6 months of ruxolitinib cream. Their DLQI score improved by 6.8 points. The NB-UVB combination was superior to monotherapy (90% facial clearance vs 67% monotherapy)²².
                257568. : No ongoing vitiligo trials of oral ruxolitinib (JAK1/2) are available. Although data are scarce, case reports indicate that systemic JAK inhibitors can be beneficial even in other extensive diseases. Oral ruxolitinib has been reported to induce repigmentation ¹⁸.
                75525023377464590.  

1. 1. 1. phase 2 study of adults with extensive non‐segmental vitiligo was conducted with upadacitinib (selective JAK1 inhibitor)⁴.At week 24 the 11 mg dose showed a significant degree of repigmentation: least‐squares mean % reduction in F-VASI: –21.3% (11mg) versus –7.6% (placebo) (p=0.0051)⁴.Total VASI (T-VASI) also improved (–10.84% vs –11.6%, p=0.0259) with 11 mg ⁴.Overall, upadacitinib may provide significant repigmentation, particularly in facial lesions. Repigmentation continued to improve through 52 weeks, without plateauing ⁴. Safety data showed a higher incidence of serious adverse events, and higher discontinuation rates in the highest dose (22 mg), as few of these were considered drug related ⁴. The most common adverse events were fatigue, headache, acne, and infections (including COVID-19)⁴. No new warning signs for thrombosis and cancer were reported yet. Phase 3 trials of upadacitinib 15 mg are ongoing.

1. 1. 144782131947286. (± Phototherapy)
      144782131947286. (JAK1/2 inhibitor) added to narrow-band UVB (NB-UVB) was efficacious. Adult patients with severe active vitiligo were given baricitinib 4 mg daily and NB-UVB twice-weekly for 36 weeks ⁵. The mean total VASI score decreased –44.8% (95% CI –58.4% to –31.3%) by week 36 versus –9.2% (–27.7% to 24.7%) in the NB-UVB-only group ⁵ (between-group P=0.02 post-hoc). In other words, baricitinib plus UVB quintupled repigmentation versus phototherapy alone. Importantly, the patients had severe refractory disease. Measures of disease activity and quality of life also improved more with baricitinib ⁵. Safety was fairly acceptable – number of AEs was similar in both groups and most were mild (sunburns, itching, viral infections)⁵. In summary, JAK inhibition added to phototherapy is effective for repigmentation ⁵.
      2759232725957398.  
      2759232725957398. a pan-JAK 1/3 inhibitor, has been used off-label to treat vitiligo both topically and systemically (oral) in both case series and small open-label studies. No large RCTs are available. In a pooled analysis of 45 vitiligo patients given JAK inhibitors (most tofacitinib or ruxolitinib with/without UVB), 57.8% had a “good” response (more than 50% repigmentation)⁸. Facial lesions were the most responsive region (70% had more than 50% repigmentation) versus only 27.3% on acral areas ⁸.In practice, tofacitinib can yield up to ~50–75% repigmentation of the lesion area, especially when combined with NB-UVB ⁸.Acneiform rash, mild infections, and elevations in lipids have been yet seen in other large indication trials ⁸.Tofacitinib has been associated with a boxed warning for infections and thromboembolism, but no such serious events have been reported yet in vitiligo studies ⁶.

1. 1. 6736462. JAK Inhibitors

Ritlecitinib (PF-06651600) a JAK3/TEC inhibitor:

In the primary 24-week phase 2b study, once daily ritlecitinib at 50 mg produced much larger mean percentage improvement in F-VASI and total VASI than placebo, indicating that it produced clinically meaningful repigmentation ¹⁵.In extension analysis, ritlecitinib 200 mg→50 mg with NB-UVB (vs. w/o) produced more repigmentation: at week 24, mean total VASI improvement was –29.4% with NB-UVB vs. –21.2% on ritlecitinib alone (LOCF analysis, P=0.043)¹⁴.Mean facial VASI improvement was –57.0% vs. –51.5% (NS) ¹⁴.The extension study confirms that NB-UVB adjunct therapy enhances the extent of repigmentation achieved with ritlecitinib monotherapy in active nonsegmental vitiligo ¹⁴.The regimen was well tolerated with no new safety signals ¹⁴.

Delgocitinib: A topical pan-JAK inhibitor with anecdotal efficacy in vitiligo and currently in early trials so it's data is limited.

Other: Ruxolitinib (oral) or Ritlecitinib were primarily in studies as above. Newer JAK inhibitors (JAKtinib, Itacitinib, etc.) can be studied.

Table 1 lists the key efficacy and safety data for these agents. Overall, JAK inhibitors enhance repigmentation of the face considerably, but more moderately the body, and are generally well tolerated. Acne, mild infections, and headache are most common adverse events ⁶ importantly, no clinically significant rates of cytopenias or thromboembolic events were observed in vitiligo studies.

Table 1. Comparison of clinical performance of JAK inhibitors in vitiligo treatment (efficacy and safety)^{2-6, 8,14}.

Table-2: Ruxolitinib Facial Repigmentation Over Time (TRuE-V Program)

Table –2 summarizes Two phase 3 RCTs (TRuE-V1/V2) followed by long-term extension demonstrate progressive and sustained facial repigmentation through 2 years with continuous ruxolitinib cream 1.5% ^19,20.

Systematic Review and Meta‐analysis Findings

In two recent systematic reviews, JAK inhibition in vitiligo has been further reinforced. Huang et al. performed a meta-analysis of five RCTs (n=1550) comparing JAK inhibitors and placebo in 2025 ⁷. We reported improved vitiligo repigmentation by JAK inhibitors, with a pooled RR for reaching 50% improvement in TVASI (TVASI50) of 2.67 (95% CI 1.24–5.78) and a RR for 75% facial repigmentation (FVASI75) of 3.97 (95% CI 2.62–6.02)⁷. Subgroup analysis indicated JAK1/2 inhibitors (ruxolitinib, baricitinib and upadacitinib) were more effective than JAK 3 inhibitors (tofacitinib, ritlecitinib)⁷.Regarding safety, JAK inhibitors and placebo had similar overall adverse event rates (treatment-emergent, serious, infections), but there were increased skin-related reactions (RR≈1.96, p<0.01)⁷.In other words, there are benefits of repigmentation, but modestly increased local skin AEs (no excess systemic toxicity in the trial population)⁷.An observational meta-analysis of case reports further contextualized patient-level outcomes. Phan et al. pooled case reports of 45 vitiligo patients treated with a JAK inhibitor (mostly tofacitinib or ruxolitinib, many were using concomitant UVB) and found 57.8% had >50% repigmentation⁸. We reported great variation in response based on treatment site: 70% of patients had good (>50%) facial repigmentation versus 27.3% on acral (hands and feet) sites ^8..Additionally, concurrent phototherapy significantly improved “good” response overall (P<0.001) and on the face (P<0.001)⁸. Based on these results, facial lesions are more likely to be easier to repigment than more distal sites, which may indicate the need for concurrent phototherapy (and perhaps combination medications) to maximize response. Overall, data indicate JAK inhibitors improve vitiligo repigmentation (particularly on the face) with a generally positive safety profile ^7,8. However, acral lesions remain a challenge, which means additional methods (phototherapy or combination medications) may be needed for later research ⁸.

Analytical Techniques for Quantification of Ruxolitinib

Precise ruxolitinib measurement is required for pharmacokinetic monitoring, stability studies, and formulation quality control. Several chromatographic methods have been validated (Table 3).

Reversed-phase HPLC–UV: Di Michele et al. (2020) have developed an achiral RP-HPLC method ⁹ with a Robusta C18 column (250 x 4.6 mm, 5 μm) and water/acetonitrile (70:30, v/v) mobile phase containing 0.1% formic acid ⁹. Under these conditions, ruxolitinib eluted at about 8.1 min. The developed methodology showed high linearity (0.006–0.17 mg/mL), precision and excellent accuracy (recovery) with an LOQ~0.002 mg/mL (2.0 µg/mL) and LOD ~0.000007 mg/mL (7 ng/mL). The accuracy (recovery) was between 96 and 106% at all tested concentrations ⁹.

RP-HPLC: The authors have reported a validated RP-HPLC method for determining ruxolitinib in commercial tablet formulations and active pharmaceutical ingredients besides pure ruxolitinib. The method uses an ODS Phenomenex column with a methanol: water (70:30, v/v; pH3.5) mobile phase composition and UV detection at 236 nm ¹⁷. The method being linear over the 20–120 µg/mL concentration range (r²≈0.9999), and having an accuracy of over 99% with LOD and LOQ values in the sub-µg/mL range, has been used for regular quality control of tablet formulation ¹⁷.

UPLC–UV: A stability-indicating UPLC method was performed by using a Phenomenex C8 column (250x4.6 mm, 5 μm) with ternary mobile phase (pH 6.2 glacial acetic acid: methanol: acetonitrile 40:30:30, v/v/v) at 65 °C and 1.0 mL/min ¹⁰.

Ruxolitinib eluted in about 3.4 min ¹⁰. The assay was linear from 50 to 150 μg/mL (r2=0.9998)¹⁰.

The LOD 2.06 μg/mL and LOQ 6.26 μg/mL values showed that the method is highly sensitive¹⁰.The method validation parameters (precision CV<2.9%, recovery 98–102%) fulfilled ICH Q2(R1) criteria ¹⁰.

LOD 2.06 μg/mL and LOQ 6.26 μg/mL for high sensitivity ¹⁰. Method validation for above parameters satisfied ICH Q2(R1) criterion (precision CV<2.9%from, recovery 98–102%) ^9,10. UPLC method is rapid, (RT~3–4 min), suitable for standard stability and quality control studies.

LC– MS/MS:  We developed a bioanalytical UHPLC–MS/MS method for ruxolitinib in human plasma (therapeutic drug monitoring study). Separation was carried out on a Thermo Hypersil GOLD C18 column (50×2.1 mm, 3.0 μm) using a gradient of 0.1% formic acid in water (A) and 0.1% formic acid in methanol (B) ¹¹. Flow rate was 0.4 mL/min and run time 3 min; ruxolitinib eluted in ~1.42 min ¹¹. Detection was done in positive ESI-MS/MS mode, monitoring the 307.1→186.1 m/z transition. The calibration curve was linear in the range 10–2000 ng/mL (r²>0.99); LLOQ was 10 ng/mL. Intra- and inter-run precision/accuracy satisfied FDA bioanalytical guidelines (±15%)¹¹. Ultra-high sensitivity of the LC-MS/MS method developed here for ruxolitinib was suitable for pharmacokinetic studies ¹¹. Recent advances in bioanalytical methods using LC-MS/MS techniques have been using to analyze ruxolitinib simultaneously in skin biopsy matrix and human plasma. The developed methods show high recovery and negligible matrix effects. This is relevant for determining the distribution of ruxolitinib in skin and plasma ^14,15.

High-resolution LC–MS (HRMS) methods have also been applied to ruxolitinib.  LC–QTOF-MS to study ruxolitinib degradation products in stress conditions ¹². The HRMS method was not intended for quantification but only for structure elucidation to ensure the drug stability ¹².

Table 3. Representative analytical methods for quantification of ruxolitinib (column, mobile phase, retention time, linearity, LOD, LOQ) ^9-11.

The validated parameters that were used in the quantification of ruxolitinib in various matrices are compiled in Table 4. The table shows the shift from traditional UV detection methods used in routine quality control to high sensitivity mass spectrometry used in the monitoring of complex biological samples.

Table-4 Analytical Technical Profile