Pilot Study of Lubiprostone as a Modulator of Gut Microbial Translocation and Systemic Immune Activation in HIV-Infected Persons With Incomplete CD4+ T-cell Recovery on Antiretroviral Therapy

Incomplete immune recovery in HIV-infected individuals is associated with impaired immune
response to antigens, opportunistic infections, cardiovascular disease and malignancies, and
increased mortality. Several studies have pointed to increased microbial translocation and
immune activation as playing a causative role in these patients with limited CD4 recovery
with antiretroviral therapy (ART). The gut mucosa of HIV-infected individuals sustains a
rapid and profound depletion of gut mucosal CD4+ T-cells as early as a few days after
infection. These changes lead to defects in mucosal immune and epithelial barrier function
that allows the translocation of gut microbial products, such as plasma LPS (endotoxin) and
bacterial 16s DNA. Plasma endotoxin and bacterial 16s DNA are elevated in HIV-infected
individuals and their levels are associated with increased levels of immune activation. ART
does not readily reverse the deficits in gut mucosal CD4+ T-cells. The epithelial barrier
composed of tight junction complexes of the GI tract is a major defense that must be
breached in order for microbial antigens and enterotoxins expressed by pathogenic bacteria
to traverse from the lumen of the intestine to the lamina propria of the GI tract. Given
recent data demonstrating increased complications and mortality in HIV-infected individuals
despite suppressed viral replication on ART, investigators have proposed that adjunctive
therapies aimed at reducing microbial translocation and/or its inflammatory consequences
could improve the long-term prognosis of HIV-infected individuals. An intervention that
decreases the level of translocated gut microbial products using modulators that act at the
mucosal tight junction barrier is a strategy that has not been studied in HIV.

LAMBCHOP is a randomized, open-label, controlled three-arm study that will test whether 4
weeks of treatment with lubiprostone, an apical lumen ClC-2 chloride channel activator
licensed for the treatment of chronic idiopathic constipation and irritable bowel syndrome
with constipation, reduces levels of translocated gut microbial products and markers of
immune activation in HIV-infected subjects on antiretroviral therapy with incomplete CD4
recovery. Lubiprostone is a potent intestinal epithelial secretagogue that has been shown to
stimulate recovery of mucosal barrier function via the restoration of tight junction protein
complexes in ex vivo studies of ischemic porcine intestine. This study will take advantage
of lubiprostone's known effect in vitro to significantly decrease E. coli and S. typhimurium
translocation in a concentration-dependent manner and in in vivo mouse studies to promote
enhanced protection against translocated pathogenic bacteria by shifting the intestinal
microbiota in order to study the role of translocated gut microbial products in driving
immune activation in HIV-infected subjects. Blood samples and stool specimens will be
collected at several time points during the study to measure markers of cellular activation,
inflammation, gut translocation, and coagulation. Safety assessments will be performed at
screening, entry, and several post-entry visits. The primary objectives of the study is to
determine whether there is a significant difference in levels of immune activation and gut
microbiome after 4 weeks of study drug in those who received lubiprostone.

Inclusion Criteria:

- HIV-1 infection, documented by any licensed rapid HIV test or HIV enzyme or
chemiluminescence immunoassay (E/CIA) test kit at any time prior to study entry and
confirmed by Western blot or a second antibody test by a method other than the
initial rapid HIV and/or E/CIA, or by HIV-1 antigen, plasma HIV-1 RNA viral load.

- On tenofovir/emtricitabine/efavirenz single tablet combination therapy for at least
72 weeks prior to study entry.

- No plans to change the antiretroviral regimen at least in the next 3 months after
study entry.

- CD4+ cell count < 350 cells/mm3 obtained within 120 days prior to study entry at any
laboratory that has a Clinical Laboratory Improvement Amendments (CLIA) certification
or its equivalent.

- All previous CD4+ cell counts should be < 350 cells/mm3 for at least 72 weeks prior
to study entry while subjects were on ART.

- Documentation of HIV-1 RNA below the limit of detection (e.g., < 50 copies/mL on
Roche Amplicor HIV-1 Monitor assay, < 75 copies/mL on the Versant HIV-1 RNA assay by
branched DNA, < 400 copies/mL on a standard Roche Amplicor assay, < 40 copies/mL on
the Abbott m2000sp/m2000rt real-time PCR test, < 48 copies/mL on the COBAS
AmpliPrep/TAQMAN HIV-1 assay) verified by at least two measurements prior to study
entry, one of which must be at least 48 weeks prior to study entry and one
measurement that was obtained between 121 days and 48 weeks prior to study entry.

- Screening HIV-1 RNA below the limit of detection obtained within 120 days prior to
study entry using a FDA -approved assay (e.g., < 50 copies/mL on Roche Amplicor HIV-1
Monitor assay, < 75 copies/mL on the Versant HIV-1 RNA assay by branched DNA, < 40
copies/mL on the Abbott m2000sp/m2000rt real-time PCR test, < 48 copies/mL on the
COBAS AmpliPrep/TAQMAN HIV-1 assay).

- Fasting laboratory values obtained within 45 days prior to entry as follows:

- Absolute neutrophil count (ANC) ≥ 1000/mm3

- Hemoglobin ≥ 10.0 g/dL

- Platelet count ≥ 50,000/mm3

- International normalized ratio (INR)

- Female subjects of reproductive potential (defined as girls who have reached menarche
or women who have not been post-menopausal for at least 24 consecutive months; i.e.,
those who have had menses within the preceding 24 months or have not undergone a
sterilization procedure [hysterectomy, bilateral oophorectomy, bilateral tubal
ligation, or bilateral salpingectomy]) must have a negative serum or urine β-HCG
pregnancy test with a sensitivity of at least 50 mIU/mL performed within 24 hours
prior to study entry.

If participating in sexual activity that could lead to pregnancy, the female subject must
agree to use one form of contraceptive as listed below while receiving protocol-specified
treatment and for 4 weeks after stopping the treatment.

- If the female subject is not of reproductive potential (girls who have not reached
menarche, women who have been post-menopausal for at least 24 consecutive months, or
women who have undergone surgical sterilization, e.g., hysterectomy, bilateral
oophorectomy, or bilateral tubal ligation or salpingectomy), she is eligible without
requiring the use of a contraceptive. Self report is acceptable documentation of
sterilization, other contraceptive methods, and menopause.

- Men and women age ≥ 18 and ≤ 65 years of age.

- Ability and willingness of subject or legally authorized representative to provide
informed consent.

Exclusion Criteria:

- Active diarrhea (3 or more unformed stools per day) within 28 days prior to study
entry (except if site investigator or primary care provider attributes diarrhea to
antiretroviral or azithromycin use).

- History of or active inflammatory bowel disease.

- History of significant liver disease, defined as having chronic liver disease
(including chronic alcoholic liver disease, hepatitis B or C), plus either: a)
ascites, b) encephalopathy, or c) a Child-Pugh Score of > 7.

- Receipt of antimicrobial therapy within 30 days prior to study entry.

NOTE: Antimicrobial use for prophylaxis of opportunistic infections, e.g., azithromycin or
trimethoprim-sulfamethoxazole, is allowed.

- Active infection requiring the use of antibiotics within 30 days prior to study
entry.

- Known allergy/sensitivity or any hypersensitivity to components of study drug or
their formulation.

- Serious illness requiring systemic treatment and/or hospitalization within 14 days
prior to entry.

- Use of any of the following medications for more than 3 consecutive days within the
60 days prior to study entry:

- Immunosuppressives (e.g., azathioprine, corticosteroids [physiologic replacement
doses are allowed], cyclosporine, mycophenolate, NSAIDs (nonsteroidal
anti-inflammatory drugs), sirolimus, sulfasalazine, tacrolimus)

- Immune modulators (e.g., cytokines [e.g., IL-2], granulocyte colony stimulating
factor, growth hormone, tumor necrosis factor antagonists, thalidomide)

- Antineoplastic agents

- Probiotics (defined as products that contain significant amounts of live
microorganisms and are ingested for specific health benefits, e.g., yogurt with
live and active cultures, Lactobacillus GG, Saccharomyces boulardii)

- Anticoagulants (e.g., warfarin and heparin)

- Vaccinations within 1 week prior to the pre-entry or study entry visits.

NOTE: Subjects are encouraged to get the flu vaccine prior to study pre-entry visit.

- Participation on any HIV immunotherapy/therapeutic vaccination trials within 6 months
prior to study entry.

- Active drug or alcohol use or dependence that, in the opinion of the site
investigator, would interfere with adherence to study requirements.

- Breastfeeding.