Pomalidomide for the Treatment of Bleeding in Hereditary Hemorrhagic Telangiectasia Longitudinal Assessment Study

Inclusion Criteria: 1. A clinical diagnosis of HHT as defined by the Curacao criteria 2. Age \> 18 years 3. Platelet count ≥ 100 x 109/L prior to pomalidomide initiation 4. WBC ≥ 2.5 x 109/L prior to pomalidomide initiation 5. INR ≤ 1.4 and normal ± 2 sec activated partial thromboplastin time (aPTT) by local laboratory criteria (except for patients on a stable dose of warfarin or direct oral anticoagulants) 6. Epistaxis severity score ≥ 3 measured over the preceding month 7. A requirement for anemia, as determined by local laboratory normal ranges, and/or parenteral infusion of at least 250 mg of iron or transfusion of 1 unit of blood over the 24 weeks preceding the screening visit 8. All study participants must agree to be registered into the FDA mandated POMALYST REMS program, and be willing and able to comply with the requirements of the POMALYST REMS program 9. Females of childbearing potential (FCBP)† must adhere to the pregnancy testing schedule mandated by the POMALYST REMS program 10. Prior enrollment on PATH-HHT study (NCT03910244) * A female of childbearing potential is a sexually mature woman who: 1) has not undergone a hysterectomy or bilateral oophorectomy; or 2) has not been naturally postmenopausal for at least 24 consecutive months (i.e., has had menses at any time in the preceding 24 consecutive months). Exclusion Criteria: 1. Women currently breast feeding or pregnant 2. Renal insufficiency, serum creatinine \> 2.0 mg/dl 3. Hepatic insufficiency, bilirubin \> 2.0 (or \>4.0 in the setting of a prior clinical or genetic diagnosis of Gilbert's syndrome) or transaminases \> 3.0x normal 4. Prior treatment with thalidomide or other non-pomalidomide immunomodulatory imide drugs (IMiDs) within previous 6 months 5. Prior treatment with bevacizumab (systemic or nasal) within previous 6 weeks 6. Prior treatment with pazopanib within previous 6 weeks 7. The use of octreotide or estrogens within the previous month 8. History of prior unprovoked thromboembolism confirmed by venous ultrasound or other imaging modalities 9. Known peripheral neuropathy, confirmed by neurologic consultation 10. Known underlying hypoproliferative anemia (i.e. myelodysplasia, aplastic anemia) 11. Currently enrolled in other drug trials 12. Known hypersensitivity to thalidomide or lenalidomide 13. The development of erythema nodosum if characterized by a desquamating rash while taking thalidomide or similar drugs 14. Known SMAD-4 mutation, unless there has been a colonoscopy with normal (negative) results, or in which the patient has had no more than 5 small (in the opinion of the gastroenterologist) colonic polyps completely removed within the preceding 18 months 15. Anything that in the investigator's opinion is likely to interfere with completion of the study