Phase I trial of a humanized, Fc receptor nonbinding OKT3 antibody, huOKT3gamma1(Ala-Ala) in the treatment of acute renal allograft rejection.

BACKGROUND: HuOKT3gamma1(Ala-Ala) is a genetically-engineered derivative of the parental murine OKT3 monoclonal antibody, in which the six complementarity-determining regions have been grafted within a human IgG1 mAb, and whose C(H)2 region has been altered by site-directed mutagenesis to alter FcR-binding activity, thereby eliminating T cell activation properties. This report describes the results of a phase I trial of huOKT3gamma1(Ala-Ala) treatment of acute renal allograft rejection. METHODS: Acute renal allograft rejection in kidney and kidney-pancreas transplant recipients was treated with huOKT3gamma1(Ala-Ala). huOKT3gamma1(Ala-Ala) dosing consisted of daily 5- or 10-mg doses adjusted initially to achieve target levels of 1000 ng/ml. RESULTS: A total of seven patients, five kidney transplant and two kidney-pancreas transplant recipients, were treated with the monoclonal antibody for first rejection episodes. Corticosteroids (500 mg i.v. Solumedrol) were given 2 hr before the first huOKT3gamma1(Ala-Ala) dose only. Banff classification of treated rejections were the following: grade I, 1 patient, grade IIA, 1 patient, grade IIB, 4 patients, and grade III, 1 patient. Median time from transplant to rejection was 15 days, and median follow up 12 months (range 10-17 months). HuOKT3gamma1(Ala-Ala) therapy was given for 10.1+/-2.5 days, and mean total dose was 76+/-27 mg. Rejection was reversed in five of seven patients, and recurrent rejection was observed in one patient. Serum creatinine values peaked on day 1 of huOKT3gamma1(Ala-Ala) therapy, and thereafter demonstrated a progressive decline. Rejection reversal (return of creatinine to baseline) occurred at a median of 4 days and a mean of 4.1+/-2 days. Renal allograft biopsies obtained during huOKT3gamma1(Ala-Ala) therapy provided evidence of rapid rejection reversal. Patient and graft survival were both 100%. First dose reactions were minimal, and anti-OKT3 antibodies were not detected. Elevations in serum IL-10, but not IL-2 levels were observed after the first huOKT3gamma1(Ala-Ala) dose. Marked reductions in circulating CD2+, CD4+, and CD8+ T cells were observed after the first huOKT3gamma1(Ala-Ala) dose, followed by a slow progressive return of cell counts toward pretreatment values. Pharmacokinetic analysis revealed a half-life of 142+/-32 hr. CONCLUSIONS: HuOKT3gamma1(Ala-Ala) possesses the ability to reverse vigorous rejection episodes in kidney and kidney-pancreas transplant recipients, and in comparison to murine OKT3, possesses minimal first dose reactions and does not seem to induce antibodies that bind the OKT3 idiotype. These results support the conduct of additional clinical trials with the huOKT3gamma1(Ala-Ala) antibody.

OKT3 escalating dose regimens provide effective therapy for renal allograft rejection.

Dose-response relationships for anti-CD3 monoclonal antibody (mAb) therapy remain undefined, particularly with respect to higher dose ranges. The clinical efficacy and safety of an OKT3 dosing regimen that incorporates higher doses (escalating dose regimens) was examined in a pilot trial. Patients undergoing acute rejection were treated with a 7-d course of OKT3 in which the daily OKT3 dose was escalated during treatment course (daily doses 5, 5, 5, 5, 10, 15, 25 mg). The total amount of OKT3 given was equal to a standard 14-d course (70 mg). A total of 10 primary cadaveric renal transplant recipients were treated, and data analyzed from a median follow up of 5 months (range 3-13 months). Pre-OKT3 immunosuppressive therapy consisted of ATGAM induction therapy (n = 8), and corticosteroid rejection therapy (n = 6, 18.6 +/- 11.4 mg/kg). Median time of first rejection was 32 d (12-48 d) and median time to OKT3 was 33 d (range 15-42 d). Pre-OKT3 histology (by Banff criteria) included: mild ACR (n = 6), moderate ACR (n = 2), AVR (n = 1), ACR and acute transplant glomerulopathy (n = 1). Rejection reversal rate with escalating dose OKT3 was 100%, and each patient experienced a rapid reversal of rejection (i.e. reversal within 14 d initiation of OKT3 therapy). Six recurrent rejection episodes were diagnosed in 5 patients with a median time to recurrent rejection of 30 d following cessation of OKT3 therapy. All recurrent rejection episodes were successfully treated (FK 506 n = 4, corticosteroids n = 1, and OKT3 n = 1). CMV disease was limited to a single episode of CMV viremia in one patient. PTLD was observed in one patient who had coexisting vascular rejection at the time of PTLD diagnosis. Short- and long-term graft function is excellent (pre-rejection baseline creatinine 1.8 +/- 0.4 mg/dl, current creatinine 1.75 +/- 0.4 mg/dl). Monitoring of OKT3 serum levels revealed that patients maintained therapeutic serum levels for an average of 4 d following the last OKT3 dose. Circulating CD3+ and CD5+ cells were maintained below baseline levels for at least 10 d following the last OKT3 dose. Anti-OKT3 antibody formation occurred in 22% of patients, however, anti-idiotypic responses were of low titer. Adverse reactions experienced during dose escalation were minimal compared to first dose reactions, and consisted primarily of mild headaches and arthralgias in a minority of patients. OKT3 EDR, by obviating monitoring and administration costs, are cost effective [OKT3 EDR $8088, OKT3 SDR (10 d) $9684, OKT3 SDR (14 d) $13,224]. In conclusion, escalating dose regimens of OKT3: 1) provide rejection reversal rates similar to standard dose regimens, 2) provide high OKT3 serum levels and reliable CD3+ cell depletion, 3) induce minimal adverse reactions during dose escalation, and 4) may decrease costs by obviating the need for monitoring peripheral blood T cells and by decreasing administration costs and outpatient visits.

Clinical and cytogenetic responses to granulocyte-macrophage colony-stimulating factor in therapy-related myelodysplasia.

We treated 10 patients with a therapy-related myelodysplastic syndrome with escalating doses of granulocyte-macrophage colony-stimulating factor (GM-CSF; sargramostim) in a phase II trial and used sequential cytogenetic analyses to determine whether there was stimulation of nonclonal hematopoiesis. The GM-CSF was administered by continuous intravenous infusion over 2 hours daily for 14 days, followed by a 14-day rest period. The initial starting dose was 60 micrograms/m2/d. The GM-CSF dose was escalated within individual patients to 125 micrograms/m2, 250 micrograms/m2, and then 500 micrograms/m2/d until the peripheral blood neutrophil count at least doubled and exceeded 1,000/microL. GM-CSF treatment then continued in monthly maintenance cycles. During 57 treatment courses, the neutrophil count increased in 52 but only doubled and exceeded 1,000/microL in 21. Mild eosinophilia was stimulated in five patients, but only two had greater than 1,000 eosinophils/microL. In only three patients was any stimulation of platelet or red blood cell production observed, and thus, little change in transfusion requirements occurred. The bone marrow karyotypes from individual patients either remained completely abnormal or became increasingly abnormal over the course of treatment. We found no evidence that GM-CSF preferentially stimulated normal marrow stem cells to proliferate or had the ability to eradicate the cytogenetically abnormal clone by inducing terminal differentiation. Although the effect on granulopoiesis was transient and dependent on continued GM-CSF treatment, the increase in the neutrophil count was clinically important in some patients, allowing more effective control of ongoing infections.

Pituitary adenoma in McCune-Albright syndrome: MR demonstration.

The magnetic resonance (MR) demonstration of a pituitary adenoma associated with McCune-Albright syndrome is presented. A useful role for routine MR imaging of the sella turcica in all cases of clinically suspected McCune-Albright syndrome is suggested. This is especially important in patients with leontiasis ossea secondary to polyostotic fibrous dysplasia involving the craniofacial bones and skull base.