Doxycycline for the Treatment of Cutaneous T-Cell Lymphoma

Inclusion Criteria: * Voluntarily signed and dated Institutional Review Board approved informed consent form in accordance with regulatory and institutional guidelines. Written informed consent must be obtained prior to performing any study-related procedure. * Be 18 years of age or older at time of enrollment. * Measurable disease in at least one target lesion in the skin or able to be assessed by radiographic examination with FDG-PET fluorodeoxyglucose possitron emission tomography (FDG-PET) scan or computarized tomography (CT) scan, or peripheral blood showing involvement of lymphoma. * The subject has resolution of all clinically significant toxic effects of prior cancer therapy to Grade ≤1 by the National Cancer Institute Common Terminology Criteria for Adverse Events, version 4.0 (NCI-CTCAE, v.4.0) excluding the specification below. * Adequate organ function: * Absolute Neutrophil Count (ANC) \> 500 cells/mL and platelet count \> 50,000 cells/mL unless felt to be secondary to lymphoma at which any count is permissible. * Adequate renal function as determined by creatinine \< 1.5x upper limit normal (ULN) or estimated creatinine clearance of ≥ 60ml/min * Adequate hepatic function as determined by total bilirubin \< 1.5x ULN (unless known Gilbert syndrome), Alanine transaminase (ALT) and Aspartate transaminase (AST) \< 2.5x ULN * Confirmed diagnosis of CTCL. * Karnofsky Performance Status ≥ 60% * Women of childbearing potential (WOCBP) must have a negative pregnancy test within 7 days of receiving study medication and monthly while on receiving doxycycline * WOCBP must agree to use effective contraception, defined as, oral contraceptives, double barrier method (condom plus spermicide or diaphragm plus spermicide) or practice true abstinence from sexual intercourse (periodic abstinence, e.g., calendar ovulation, symptothermal, post-ovulation methods and withdrawal are not acceptable methods of contraception) during the study and for 3 months after the last dose. WOCBP includes any female who has experienced menarche and who has not undergone successful surgical sterilization or is not postmenopausal (defined as amenorrhea ≥ 12 consecutive months without an alternative medical cause). * Male subjects and their female partners of child bearing potential must be willing to use an appropriate method of contraception defined as, oral contraceptives, double barrier method (condom plus spermicide or diaphragm plus spermicide) or practice true abstinence from sexual intercourse (periodic abstinence, e.g., calendar, ovulation, symptothermal, post-ovulation methods and withdrawal are not acceptable methods of contraception) during the study and for 3 months after the last dose. Exclusion Criteria: * Known sensitivity or allergy to tetracyclines * Lack of measurable disease * Karnofsky Performance Status \<60% * Inadequate organ function as measured by not fulfilling above criteria * Subject is pregnant or breast-feeding.