• The proportion of subjects who acheive a score of clear (0) on the PGA of LMB at week 2. [ Time Frame: 2 weeks ] [ Designated as safety issue: No ]
  

• The proportion of subjects who acheive a score of clear (0) or almost clear (1) on the PGA og LMB at weeks 4 and 6. [ Time Frame: Four and six weeks. ] [ Designated as safety issue: No ]
  
• The incidence of adverse events caused by calcipotriene/betamethasone (Taclonex) at weeks 2, 4 and 6. [ Time Frame: Weeks 2, 4 and 6 ] [ Designated as safety issue: Yes ]
  

Drug: Calcipotriene/betamethasone
One application to affected areas, once a day for two weeks. The PI may choose to extend treatment until Week 4 if necessary.

LMB (localized mild breakthrough)is one of two psoriasis adverse events commonly seen in efalizumab treated patients. It is generally papular in nature and does not involve existing lesions. Clinical experience suggests that LMB may not have a clinical impact in patients responding to efalizumab and therefore may be treated without interrupting efalizumab therapy. To relieve discomfort topical therapy may be indicated until the symptoms are resolved.

This is a single arm, open label study. Fifteen patients who are receiving efalizumab before entrance into this study and who develop LMB wil be enrolled. Topical calcipotriene/betamethasone (Taclonex) will be applied to the areas (except face, axillae or groin) once a day for two weeks. The PI may choose to continue two more weeks if needed for a total of four weeks of therapy. All patients will continue with efalizumab without dose modification for the duration of the study. Patients will return for follow up visits at weeks 2, 4 and 6. Topical desonide may be used for LMB involvement of the face, groin or axillae.

Inclusion Criteria:

• Ability to provide written, informed consent and comply with study assessments for the full duration of the study.
• Age 18 years or older.
• Moderate to severe plaque psoriasis being treated with efalizumab.
• Develop LMB during efalizumab treatment.
• PGA of LMB at least mild (2) excluding face, axillae and groin.

Exclusion Criteria:

• Patients with known hypersensitivity to efalizumab, calcipotriene/betamethasone or any of its components.
• Pregnant or lactating women.
• Known or suspected disorders of calcium metabolism.
• Erythrodermic, exfoliative and/or pustular psoriasis.
• Concomitant use of topical thaerapy, phototherapy or immunosuppressive agents.
• LMB (in areas other than face, axillae or groin) constitutes more than 30% of total body surface area.
• Patients with generalized inflammatory flare which is defined as widespread worsening of psoriasis characterized by erythematous and and edematous lesions within exisiting plaques.
• Any other condition the investigator believes would pose a significant hazard to the subject if the investigational therapy were initiated.