This is a phase 2, randomized, double-blind, parallel-group, single dose study to evaluate the safety and efficacy of 2 dose levels of REGN475 compared with placebo in patients with sciatic pain. Enrollment of approximately 50 patients in each of the 3 treatment arms is expected at up to 35 US sites, for a total enrollment of approximately 150 patients. Patients will receive 1 injection under the skin of either active or placebo REGN475, and be followed over 10 visits for 12 weeks.

Inclusion Criteria:

1. Pain present for at least 2 weeks, but not lasting for more than 16 weeks prior to the screening visit.
2. A confirmed diagnosis of sciatica at the screening visit.
3. Weight less than 120 kg

Exclusion Criteria:

1. Back surgery within 6 months prior to the screening visit
2. Neurological deficit (muscle weakness and/or reflex loss; loss of bowel or bladder function) from any cause including sciatica
3. Other conditions which may confound the interpretation of the study, such as carpal tunnel syndrome, MS, rheumatoid arthritis, spinal stenosis, etc.
4. Allergy to doxycycline or related compounds
5. Women who are pregnant or nursing