Linezolid Dosing Strategies in Drug-Resistant TB

A Phase II, Prospective, Randomized, Multicenter Trial to Evaluate the Efficacy and Safety/Tolerability of Two Linezolid Dosing Strategies in Combination With a Short Course Regimen for the Treatment of Drug-Resistant Pulmonary Tuberculosis

The purpose of the study was to evaluate the efficacy (how well the medicines work) and tolerability (whether participants stop treatment because of side effects from a drug) of an anti-TB treatment regimen that compared two doses of linezolid (LZD), combined with bedaquiline (BDQ), delamanid (DLM), and clofazimine (CFZ). This study also measured the level of LZD and BDQ in the participants' blood.

When the study was designed, there was currently no "standard of care" or single standardized treatment regimen recommended for everyone with drug resistant-tuberculosis (DR-TB). Current DR-TB treatments were not well tolerated and often had side effects. There was a need to identify drugs with enough anti-TB activity (treatment against TB) and good safety profiles that could improve outcomes in the treatment of DR-TB.

The main purpose of this study was to evaluate the efficacy and tolerability of a new shorter course anti-TB treatment regimen that compared two dosing strategies of linezolid (LZD), combined with bedaquiline (BDQ), delamanid (DLM), and clofazimine (CFZ). As a secondary aim, the study assessed the safety (the level and type of side effects from a drug or treatment) of the combination of these drugs.

Everyone in the study took BDQ, DLM, and CFZ once a day for the entire treatment period. The difference between the two treatment groups in the study was in how participants took the fourth drug: LZD. Participants in group A took one dose of LZD once a day for the entire treatment period. Participants in group B took a higher dose of LZD once a day for 4 weeks and then took that higher dose of LZD just three times a week for the rest of the treatment period.

Inclusion Criteria:

1. Newly diagnosed pulmonary drug-resistant tuberculosis (DR-TB), with resistance to at least rifampicin or rifampin (which is a drug used in the therapy of tuberculosis) confirmed from a sputum specimen collected within 60 days prior to entry.

2. HIV-1 infection status documented as either absent or present.

3. For participants living with HIV, either currently on an antiretroviral therapy (ART) regimen or willing and able to start ART within 30 days after entry.

4. Efavirenz or etravirine (drugs used to treat HIV) must be discontinued prior to a participant's starting anti-TB medications. For participants on efavirenz or etravirine, they must be willing and able to discontinue these at least 7 days prior to initiating study TB medications.

5. For participants living with HIV, CD4+ cell (a type of white blood cell) count greater than or equal to 50 cells/mm3 obtained within 60 days prior to study entry.

6. For females of reproductive potential, negative serum or urine pregnancy test.

7. Females of reproductive potential who are participating in sexual activity that could lead to pregnancy must agree to use two of the following forms of birth control while receiving TB study medications and for 30 days after stopping study medications:

   • Male or female condoms
   • Diaphragm or cervical cap (with spermicide, if available)
   • Intrauterine device (IUD) or intrauterine system (IUS)
   • Hormone-based birth control (e.g., oral contraceptives, Depo-Provera, NuvaRing, implants)

8. Appropriate laboratory values as determined by the study doctor obtained within 14 days prior to entry.

9. Karnofsky performance score (an assessment tool for functional impairment) greater than or equal to 50 within 30 days prior to entry.

10. Ability and willingness of candidate and/or legal guardian/representative to provide informed consent and meet requirements for the study.

11. Chest X-ray obtained within 30 days prior to entry.

Exclusion Criteria:

1. Documentation of clinically significant (as judged by the study doctor) active infections (including HIV-related opportunistic infections) other than TB and HIV requiring treatment within 30 days prior to entry.
2. Evidence of clinically significant (as judged by the study doctor) metabolic, gastrointestinal, cardiovascular, musculoskeletal, ophthalmological, pulmonary, neurological, psychiatric, endocrine diseases, malignancy, or other abnormalities (other than the indication being studied) that would interfere with study medications or procedures.
3. Inability to take oral medications.
4. Suspected or documented TB involving the central nervous system, clinically significant renal TB or TB pericarditis, or current extrapulmonary TB involving other organ systems that might interfere with study medications or procedures, as judged by the study doctor.
5. Prior treatment with one or more of the study drugs at any time in the past for an episode of DR-TB that is not the qualifying episode or treatment for more than 7 cumulative days with one or more of the study drugs within 30 days prior to entry for the qualifying episode of DR-TB.
6. History of allergy or hypersensitivity to any of the study drugs or medications in the same class as the study drugs.
7. Known or suspected current alcohol and/or drug abuse that is, in the opinion of the study doctor, sufficient to compromise the safety and/or cooperation of the participant.
8. Receipt of any investigational drugs within 60 days prior to entry.
9. Known history of prolonged QT syndrome (heart rhythm condition that can potentially cause fast, chaotic heartbeats) or current prolonged QT interval on screening electrocardiogram (a medical test that detects cardiac (heart) abnormalities).
10. Known history of clinically significant cardiac arrhythmia (a condition in which the heart beats with an irregular or abnormal rhythm) requiring medication or clinically significant electrocardiogram (ECG) abnormality, in the opinion of the study doctor, within 60 days prior to entry.
11. Pregnancy or current breastfeeding, or intent to become pregnant and/or breastfeed while on study treatment.
12. Current use of monoamine oxidase inhibitors (type of medication used to treat depression) or use within 30 days prior to entry.
13. Current use of serotonergic agents including SSRI/SNRI antidepressants or prior use within 30 days prior to entry.
14. Known history of optic neuropathy (damage to the optic nerve in your eye) of any grade as diagnosed by an ophthalmologist.
15. Current peripheral neuropathy (when nerves are damaged or destroyed and can't send messages from the brain and spinal cord to the muscles, skin and other parts of the body) with severe paresthesias ("pins and needles") and/or mild weakness or worse (Grade ≥2.).
16. Weight less than 35 kg (77 lbs).
17. Currently taking other prohibited medications.