Background/Purpose:

Fibromyalgia (FM) is a common chronic pain syndrome with symptoms that include widespread pain, fatigue, sleep disruption and cognitive impairment.  It is known that infections and other types of stressors are capable of triggering the development of FM.  We hypothesize that these stressors could be responsible for triggering a reactivation of latent herpesviruses, and that this reactivation could in turn lead to the central nervous system dysregulation seen in this condition.    The present study was designed to evaluate an anti-viral drug combination selected for activity against herpes class viruses.

Methods:

A total of 143 patients selected using the ACR 2010 FM criteria were enrolled at 12 sites in a 16-week, double-blind, placebo-controlled trial.  Patients were randomized (1:1) to receive a proprietary combination of celecoxib + famciclovir or placebo.  Outcome measures included a 24-hour recall pain numeric rating scale (NRS), Fibromyalgia Impact Questionnaire (FIQ-R), Patient Global Impression of Change (PGIC), and the PROMIS fatigue short form at baseline, and after 6, 12 and 16 weeks of study participation. 

Results:

The primary efficacy endpoint was change in pain from baseline.  Pain reduction was evaluated using the pain NRS and the 7-day recall pain item from the FIQ-R.  Change from baseline was determined using an MMRM approach with LOCF/ BOCF imputation for missing data.  A significant decrease in pain was observed for patients on treatment vs. placebo at 16 weeks by both measures.  The absolute change on the NRS was -1.9 units vs -1.1, comparing active to placebo (p=0.031).  On the FIQ-R item, the change was -2.2 vs -0.92 (p=0.001).  Key secondary endpoints included analysis of the PGIC, where a value of “1” or “2” was considered a clinical responder.  Significantly improved PGIC response rates were noted at endpoint: 33.3% for active vs 19.2% in placebo patients (p=0.031).  Total FIQR score change at the endpoint visit was -17.54 vs -7.87 (p=0.002), while changes in the 3 domains were 14.29 vs -5.44 (p=0.004) for Function, -4.29 vs -1.89 (p=0.003) for Overall Impact, and -16.77 vs -7.90 (p=0.004) for Symptoms.  In addition, improvements in fatigue were seen at endpoint on the PROMIS fatigue (-7.62 units vs -4.15; p=0.020).

The safety profile was especially encouraging.  Despite the celecoxib component, gastrointestinal and nervous system treatment emergent adverse events were reported significantly more often in the placebo treatment group (GI:  29.0% vs 42.5%; nervous system:  17.4% vs 23.3%; active to placebo), and study completion rates favored active treatment over placebo (82.6% vs. 60.8%) (largely driven by higher placebo discontinuation rates due to adverse events and lack of efficacy). 

Conclusion:

A proprietary combination of famciclovir, which we postulate is inhibiting herpesvirus replication, and celecoxib, known to inhibit both herpesvirus replication and reactivation, was efficacious in treating multiple symptoms of FM.   Given the simultaneous improvement in many domains and the surprising tolerability of this combination of drugs, we believe this combination warrants further study as a potential new therapy for fibromyalgia patients.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/a-combination-of-celecoxib-and-famciclovir-is-efficacious-in-the-treatment-of-fibromyalgia-results-of-a-phase-iia-randomized-double-blind-placebo-controlled-study/