Predicting cross-reactive immunological material (CRIM) status in Pompe disease using GAA mutations: lessons learned from 10 years of clinical laboratory testing experience.

Enzyme replacement therapy (ERT) for Pompe disease using recombinant acid alpha-glucosidase (rhGAA) has resulted in increased survival although the clinical response is variable. Cross-reactive immunological material (CRIM)-negative status has been recognized as a poor prognostic factor. CRIM-negative patients make no GAA protein and develop sustained high antibody titers to ERT that render the treatment ineffective. Antibody titers are generally low for the majority of CRIM-positive patients and there is typically a better clinical outcome. Because immunomodulation has been found to be most effective in CRIM-negative patients prior to, or shortly after, initiation of ERT, knowledge of CRIM status is important before ERT is begun. We have analyzed 243 patients with infantile Pompe disease using a Western blot method for determining CRIM status and using cultured skin fibroblasts. Sixty-one out of 243 (25.1%) patients tested from various ethnic backgrounds were found to be CRIM-negative. We then correlated the CRIM results with GAA gene mutations where available (52 CRIM-negative and 88 CRIM-positive patients). We found that, in most cases, CRIM status can be predicted from GAA mutations, potentially circumventing the need for invasive skin biopsy and time wasted in culturing cells in the future. Continued studies in this area will help to increase the power of GAA gene mutations in predicting CRIM status as well as possibly identifying CRIM-positive patients who are at risk for developing high antibody titers.

Bali DS ，Goldstein JL ，Banugaria S ，Dai J ，Mackey J ，Rehder C ，Kishnani PS ... -  《-》

A new assay for fast, reliable CRIM status determination in infantile-onset Pompe disease.

Pompe disease is caused by a deficiency of acid α-glucosidase (GAA; EC, 3.2.1.20), and the infantile-onset form is rapidly fatal if left untreated. However, recombinant human GAA (rhGAA) enzyme replacement therapy (ERT) extends survival for infantile Pompe patients. Although cross-reactive immunologic material (CRIM)-negative patients, who lack detectable endogenous GAA, mount an immune response to rhGAA that renders the therapy ineffective, timely induction of immune tolerance in these patients may improve clinical outcomes. Previously, CRIM status has been determined by Western blot analysis in cultured skin fibroblasts, a process that can take a few weeks. We present a blood-based CRIM assay that can yield results within 48 to 72 h. Results from this assay have been confirmed by GAA Western blot analysis in fibroblasts or by GAA sequencing in a small number of Pompe disease patients. Rapid classification of CRIM status will assist in identifying the most effective treatment course and minimizing treatment delays in patients with infantile-onset Pompe disease.

Wang Z ，Okamoto P ，Keutzer J 《-》

CRIM-negative infantile Pompe disease: characterization of immune responses in patients treated with ERT monotherapy.

Berrier KL ，Kazi ZB ，Prater SN ，Bali DS ，Goldstein J ，Stefanescu MC ，Rehder CW ，Botha EG ，Ellaway C ，Bhattacharya K ，Tylki-Szymanska A ，Karabul N ，Rosenberg AS ，Kishnani PS ... -  《-》

Successful immune tolerance induction to enzyme replacement therapy in CRIM-negative infantile Pompe disease.

Messinger YH ，Mendelsohn NJ ，Rhead W ，Dimmock D ，Hershkovitz E ，Champion M ，Jones SA ，Olson R ，White A ，Wells C ，Bali D ，Case LE ，Young SP ，Rosenberg AS ，Kishnani PS ... -  《-》

A Race Against Time-Changing the Natural History of CRIM Negative Infantile Pompe Disease.

We report the clinical course of the first prenatally diagnosed cross-reactive immunologic material (CRIM)-negative infantile Pompe disease (IPD) patient [homozygous for c.2560C>T (p.Arg854X) variant in the GAA gene] to undergo prophylactic immune tolerance induction (ITI) and enzyme replacement therapy (ERT) within the first 2 days of life. Both parents were found to be carriers of the c.2560C>T (p.Arg854X) variant through prenatal carrier screening. Fetal echocardiogram at 31 weeks of gestation showed left ventricular hypertrophy. An echocardiogram on the 1st day of life revealed marked biventricular hypertrophy. Physical exam was significant for macroglossia and hypotonia. A short course of Prophylactic ITI with rituximab, methotrexate, and intravenous immunoglobulin (IVIG) in conjunction with ERT at a dose of 20 mg/kg every other week was started on day 2 of life. The patient completed the ITI protocol safely and complete B-cell recovery, based on CD19 count, was noted by 3 months of age. The patient never developed anti-rhGAA IgG antibodies to ERT. Vaccinations were initiated at 9 months of age, with adequate response noted. Complete recovery of cardiac function and left ventricular mass was seen by 11 weeks of age. At 8 months of age, the patient developmentally measured at 75-90% on the Alberta Infant Motor Scale, walked at 11 months and continues to develop age-appropriately at 50 months of age based on the Early Learning Accomplishment Profile. ERT dosing was increased to 40 mg/kg every 2 weeks at 32 months of age and frequency increased to 40 mg/kg every week at 47 months of age. Patient continues to have undetectable antibody titers, most recently at age 50 months and urine Hex4 has remained normal. To our knowledge, this is the first report of successful early ERT and ITI in a prenatally diagnosed CRIM-negative IPD patient and the youngest IPD patient to receive ITI safely. With the addition of Pompe disease to the Recommended Uniform Screening Panel(RUSP) and its addition to multiple state newborn screening programs, our case highlights the benefits of early diagnosis and timely initiation of treatment in babies with Pompe disease, who represent the most severe end of the disease spectrum.

Gupta P ，Shayota BJ ，Desai AK ，Kiblawi F ，Myridakis D ，Messina J ，Tah P ，Tambini-King L ，Kishnani PS ... -  《Frontiers in Immunology》