Study of STX-100 in Renal Transplant Patients With Interstitial Fibrosis and Tubular Atrophy (IF/TA)

Inclusion Criteria: * Consenting adult patients, 18 (or the legal age of consent) to 65 years old, male or female. * eGFR ≥ 25 ml/min (Cockcroft-Gault formula). * Six to 60 months post renal transplant at the initiation of screening. * Qualifying renal biopsy obtained within 8 weeks prior to randomization with histologic evidence of ≥ Grade 2 IF/TA (Banff score) without morphologic evidence of a treatable etiology (e.g., BK virus nephropathy, chronic obstruction). * Adequate bone marrow and liver function * Weight between 40-110 kg. * Female patients must be surgically sterile, postmenopausal (minimum 1 year without menses and verified by follicular-stimulating hormone \[FSH\] levels), or agree to use contraception from the time of signing the informed consent form through 16 weeks following the last injection of study medication. Male patients must also agree to use birth control for either themselves or their partner, as appropriate, from the time of signing the informed consent form through 16 weeks following the last injection of study medication. Exclusion Criteria: * Recipient of a multi-organ transplant. * History of T-cell mediated rejection (TCMR) within 3 months prior to randomization. * Patients who are receiving high dose corticosteroids at the time of screening. * Histologic evidence of acute TCMR (≥ Banff Grade 1A) on a qualifying renal biopsy for this study. Patients with 'borderline' changes (Banff criteria) on a qualifying renal biopsy are eligible for thi…