A single center study of 30 patient receiving Narrowband UVB phototherapy three times weekly for 12 weeks. Patients will be evaluated through week 36 to evaluate maintenance of response.

30 subjects will be treated with increasing doses of Narrowband Ultraviolet phototherapy three times weekly for 12 weeks. Patients will then be evaluated every 6 weeks through week 36 to determine maintenance of response.

Inclusion Criteria:

1. Male or female adults ≥ 18 years of age.
2. Diagnosis of chronic plaque-type psoriasis for at least 6 months
3. Moderate to Severe plaque psoriasis as defined by BSA ≥10 PASI ≥12 IGA ≥3
4. Able to give written informed consent prior to performance of any study related procedures
5. Subject is able to attend Narrowband UVB phototherapy sessions three times a week and all other protocol specified visits
6. Subject must be in general good health (except for psoriasis) as judged by the Investigator, based on medical history, physical examination.

Exclusion Criteria:

1. Forms of psoriasis other than chronic plaque-type (e.g., pustular, erythrodermic, and/or guttate psoriasis) or drug induced psoriasis
2. History of photosensitivity
3. Subject has used ustekinumab and/or anti-IL-17 biologic therapy within 24 weeks or other experimental or commercially available biologic immune modulator(s) within 12 weeks prior to the first IP dose.
4. Use of any investigational drug within 4 weeks prior to randomization, or within 5 pharmacokinetic/pharmacodynamic half lives, if known (whichever is longer).
5. Use of oral systemic medications for the treatment of psoriasis within 4 weeks (includes, but not limited to, oral corticosteroids, methotrexate, acitretin, apremilast and cyclosporine).
6. Patient used topical therapies to treat within 2 weeks of the Baseline Visit (includes, but not limited to, topical corticosteroids, vitamin D analogs, or retinoids).
7. Initiated within 3 months, planned initiation of, or changes to, concomitant medications that could affect psoriasis vulgaris (e.g. beta blockers, antimalarial drugs, lithium, ACE inhibitors ) during the trial
8. Active infections requiring antibiotics in the 2 weeks prior to Baseline
9. Patient received UVB phototherapy within 4 weeks of Baseline.
10. Patient received PUVA phototherapy within 4 weeks of Baseline.