Takeshi Sainoh, Sumihisa Orita, Masayuki Miyagi, Miyako Suzuki-Narita, Yoshihiro Sakuma, Yasuhiro Oikawa, Go Kubota, Jun Sato, Yasuhiro Shiga, Kazuki Fujimoto, Yawara Eguchi, Masao Koda, Yasuchika Aoki, Tsutomu Akazawa, Takeo Furuya, Junichi Nakamura, Hiroshi Takahashi, Satoshi Maki, Masahiro Inoue, Hideyuki Kinoshita, Masaki Norimoto, Takashi Sato, Masashi Sato, Masahiro Suzuki, Keigo Enomoto, Hiromitsu Takaoka, Norichika Mizuki, Takashi Hozumi, Ryuto Tsuchiya, Geundong Kim, Takuma Otagiri, Tomohito Mukaihata, Takahisa Hishiya, Seiji Ohtori, and Kazuhide Inage
Study Design Prospective cohort study (open-label, single-arm, and non-blinded). Purpose This study aims to determine the effects of systemic administration of tocilizumab, an anti-interleukin-6 (IL-6) receptor antibody on refractory low back pain and leg symptoms. Overview of Literature IL-6 overexpression is associated with neuropathic pain pathogenesis, which is potentially followed by chronic low back pain, including leg pain and numbness. This finding suggest that inhibition of IL-6 at the site of pain or in the transmission pathway could provide novel therapeutic targets for chronic low back pain. Methods This prospective, single-arm study included 11 patients (eight men; mean age, 62.7 years) with ≥3-months’ chronic pain history due to lumbar disease. Subcutaneous TCZ injections were administered twice, at a 2-week interval. We evaluated low back pain, leg pain, and leg numbness using numeric rating scales and the Oswestry Disability Index (ODI; baseline and 6 months postinjection); serum IL-6 and tumor necrosis factor-α levels (baseline and 1 month postinjection); and clinical adverse events. Results Intractable symptoms reduced after TCZ administration. Low back pain improved for 6 months. Improvements in leg pain and numbness peaked at 4 and 1 month, respectively. Improvements in ODI were significant at 1 month and peaked at 4 months. Serum IL-6 was increased at 1 month. IL-6 responders (i.e., patients with IL-6 increases >10 pg/mL) showed particularly significant improvements in leg pain at 2 weeks, 1 month, and 2 months compared with nonresponders. We observed no apparent adverse events. Conclusions Systemic TCZ administration improved symptoms effectively for 6 months, with peak improvements at 1–4 months and no adverse events. Changing serum IL-6 levels correlated with leg pain improvements; further studies are warranted to elucidate the mechanistic connections between lumbar disorders and inflammatory cytokines.