10 patients with chronic genotype 1 HCV infection and mixed cryoglobulinemia will be treated with Ledipasvir/Sofosbuvir 90mg/400 mg FDC once daily for 12 weeks (naïve subjects or non-cirrhotic treatment experienced subjects) or 24 weeks (treatment experienced subjects with cirrhosis).

The researchers anticipate that approximately 20% of subjects may have cirrhosis.

The treatment of extrahepatic disease manifestations of HCV has largely paralleled that of hepatic disease. Interferon was reported to have efficacy for MC even before linkage of the syndrome to HCV in 1989, and successful combination therapy with ribavirin was found to eliminate virus and lead to the resolution of immunologic abnormalities associated with extrahepatic disease. In addition, ~75% of HCV-associated indolent asymptomatic lymphoproliferative diseases remit with successful antiviral therapy. However, in many instances, MC (notably cutaneous vasculitis) will relapse with recurrence of virus, and may occasionally persist even after clearance. In particular, side effects of Interferon alpha, including the uncovering of frank autoimmune disease, theoretically may mitigate response of extrahepatic disease to treatment. Peg-interferon increased the response rate of MC, and decreased the duration of treatment, but side effects remained problematic.

An alternative approach to the treatment of MC has been the use of immunomodulatory agents. In particular, B-cell expansion in peripheral blood and in lymphoid follicles in the liver prevalent amongst HCV-infected persons provided a rationale for the use of depletion as a therapeutic strategy. Rituximab (anti-CD20) monotherapy has been used mostly for treatment failures/intolerance or in the setting NHL, and has yielded response rates in the setting of involvement of skin (73%); MPGN (70%); joint (53%); and nerve (36%). However, this monoclonal antibody (MAb) has the potential to form immune-complexes with mixed cryoglobulin RF and cause clinical vasculitis in patients with high cryocrits, and may raise the HCV RNA level in rare patients, causing cytotoxicity. Following Rituximab with Peg-IFN plus ribavirin achieved greater than a 60% complete response (CR) in patients resistant to combination treatment alone. Other approaches include the use of Aldesleukin, an inducer of regulatory T-cell activity, MAbs targeted to specific B-cell subsets or costimulatory signal molecules (e.g. BAFF) or agents inhibiting the interaction of HCV core antigen with C1q in cryoprecipitates via the receptor for the globular domain of C1q (gC1qR).

The development of low molecular weight inhibitors of the non-structural proteins (NSPs) elaborated by HCV, in particular 5A, 5B nucleoside and non-nucleoside polymerase inhibitors, and inhibitors of 3/4A serine proteases; to selectively inhibit HCV replication has raised the prospect of "all-oral" treatment for both hepatic and extrahepatic manifestations of disease. However, the use of first generation direct-acting antiviral agents (Telaprevir® and Boceprevir® linear NS3/4A protease inhibitors) was limited by frequent escape mutants, efficacy restricted to genotype-1, need to retain protocols including PegIFN and ribavirin, potential for significant drug interactions, and serious side effects. In a trial of combination therapy including Telaprevir® for 13 patients with MC, all had significant AEs, including asthenia (92%), anemia (84%), neutropenia and bacterial infection (54%). Approval of an uridine nucleoside analogue that selectively inhibits HCV NS5B RNA-dependent RNA polymerase (Sofosbuvir) by the FDA late 2013 has led to proof-of-concept trials in which combination all-oral therapy has proven effective for both genotype 1 and other genotypes, with a number of other regimens under development. In particular, the combination of Sobosbuvir (SOF) and Ledipasvir (LDV) has been reported to have almost universal efficacy in a 12 week regimen for genotype 1, and the combination of SOF and Ribavirin (RBV) for genotypes 2-6 in a 24 week regimen. However, persistence of cryoglobulinemia even after viral clearance with the newer regimens has also raised the question of whether longer treatment regimens may be appropriate in the setting of significant extrahepatic disease. Thus, the timing is right to initiate a trial of all-oral treatment to rigorously evaluate the effect on extrahepatic disease, and to re-establish the efficacy of antiviral therapy in halting the direct and indirect role of HCV in driving autoimmune disease and lymphoproliferation. Using an interferon-sparing regimen to treat patients with HCV-related cryoglobulinemia will help answer the question as to whether immunomodulating therapy plays a role at all in eradicating cryoglobulins long-term, and whether antiviral therapy alone is adequate. If the latter, appreciable morbidity and mortality may be saved in avoiding treating these potentially sick, often cirrhotic patients, with immunomodulatory therapies.

Subjects must meet all of the following inclusion criteria to be eligible for participation in this study.

1. Willing and able to provide written informed consent

2. Male or female, age ≥18 years

3. HCV RNA ≥ 15 IU/mL at Screening

4. HCV genotype 1

5. Chronic HCV infection (≥ 6 months) documented by prior medical history or liver biopsy

6. Classification as treatment naïve or treatment experienced:

   1. Treatment naïve is defined as having never been exposed to approved or experimental HCV-specific direct-acting antiviral agents or prior treatment of HCV with interferon or ribavirin or DAAs (except for SOF-containing regimens).
   2. Treatment experienced is defined as prior treatment failure or relapse to a regimen containing interferon either with or without RBV or DAAs (except for SOF-containing regimens) that was completed at least 8 weeks prior to Baseline/Day 1.

   The subject's medical records must include sufficient detail of prior virologic failure to allow for categorization of prior response, as either:

   1. Non-Responder: Subject did not achieve undetectable HCV RNA levels while on treatment, or
   2. Relapse/Breakthrough: Subject achieved undetectable HCV RNA levels during treatment or within 4 weeks of the end of treatment but did not achieve SVR.

7. Cirrhosis determination (approximately 20% of subjects may have cirrhosis) a. Cirrhosis is defined as any one of the following:

   i) Any previous liver biopsy showing cirrhosis (e.g., Metavir score = 4 or Ishak score ≥5) ii) FibroMeter® score >0.442 or an AST:platelet ratio index (APRI) >2 during Screening iii) Fibroscan with a result of >12.5 kPa at any time prior to or during screening.

   b. Absence of cirrhosis is defined as any one of the following: i) Liver biopsy within 2 years of Screening showing absence of cirrhosis ii) FibroMeter® score <0.442 or APRI ≤ 1 performed during Screening iii) Fibroscan with a result of ≤12.5 kPa within 6 months of Baseline/Day 1 Fibroscan results will supersede FibroMeter® /APRI; liver biopsy results will supersede Fibrotest® /APRI or Fibroscan results and be considered definitive.

8. Liver imaging (ultrasound, CT scan or MRI) within 6 months of screening is required in patients with cirrhosis to exclude hepatocellular carcinoma (HCC)

9. Presence of MC vasculitis (please see criteria on the note below).

10. Null or partial response to previous therapies for MC, including corticosteroids, cytotoxic agents (cyclophosphamide, azathioprine), hydroxychloroquine, methotrexate, mono- or combination therapy with IFNα/PEG-IFN and ribavirin, and/or CD20 depletion with Rituximab. a. Patients can be on ongoing treatment with one of the drugs described above at inclusion unless there is significant DDI.

11. Subjects has the following laboratory parameters at screening:

    1. ALT <10 x the upper limit of normal (ULN)
    2. AST <10 x ULN
    3. Adequate bone marrow function as indicated hematologic parameters listed below and/or bone marrow cellularity >60-70% average for age.

    i. WBC >1500 /uL ii.Platelets > 50,000/uL

    d) Direct bilirubin >2 x ULN e) INR >1.5 x ULN unless subject has known hemophilia or is stable on an anticoagulant regimen affecting INR

12. Females of childbearing potential must have a negative serum pregnancy test at Screening and a negative urine pregnancy test on Baseline/Day 1 prior to treatment.

13. Male subjects and female subjects of childbearing potential who engage in heterosexual intercourse must agree to use protocol specified method(s) of contraception.

14. Lactating females must agree to discontinue nursing before the study drug is administered.

15. Subject must be of generally good health, with the exception of chronic HCV infection, as determined by the Investigator.

16. Subject must be able to comply with the dosing instructions for study drug administration and able to complete the study schedule of assessments.

Note: Definition of Mixed Cryoglobulinemia (patients must meet one of the five overlapping syndromes listed below and the presence of cold-precipitable immune complexes in blood on two different occasions.

• Clinical evidence of cryoglobulinemia, overlapping syndromes:

  1. Cutaneous vasculitis (Raynaud's phenomenon, purpura, skin ulcers, livedo, acrocyanosis)

  2. Glomerulonephritis (hypertension, hematuria, nephrotic syndrome)

  3. Arthropathy (arthralgias, arthritis)

  4. Neuropathy (peripheral and/or central nervous system, distal sensorimotor, mononeuritis multiplex)

  5. Sicca syndrome (xerostomia, xerophthalmia)

     Other factors that will be assessed / recorded in patients with MC will be:

  1. Associated laboratory abnormalities including:

• Positive HCV serology (recombinant immunoblot assay), viral nucleic acid quantitation diagnostic for HCV infection, and reflex genotyping.

• Evidence of glomerulonephritis, including an active urinary sediment, hypoalbuminemia (albumin <3gm/dL) and/or significant proteinuria (>300mg/day).

• Abnormal nerve conduction testing. 2. Pathologic evidence of cryoglobulinemia including:

• Leukocytoclastic vasculitis.

• Membranoproliferative glomerulonephritis.

• Vasculopathy and/or mononuclear cell infiltrates on sural nerve biopsy.

• Lip biopsy suggestive for Sjogren's syndrome. 3. Laboratory evidence of cryoglobulinemia including:

• Characterization of cryoprecipitable material in serum by immunofixation, cryocrit, and/or quantitation of protein.

• Associated immunological abnormalities, such as depressed levels of complement, elevated titers of rheumatoid factor, abnormal immunoglobulin quantitations, and serum immunofixation carried out on serum and/or isolated cryoglobulins.

  4. Laboratory evidence of B-cell clonality, including:

• IgMk determined by immunofixation of serum and/or cryoglobulin, and kappa excess >2.65:1 on Free Light Chain (FLC) assay

up to 24 weeks after treatment