Table 2.

Comparison of longitudinal immune response between ERT monotherapy and TLD-MTX groups¹

CRIM-positive IOPD on ERT monotherapy (n=37)
Groups	HSAT	SIT	LT
Percent	13.5% (n=5)	18.9% (n=7)	67.6% (n=25)
Median titers (Week 12)	25,600 (range: 12,800–51,200)	12,800 (range: 6,400–25,600)	400 (range: 0–6,400)
Median titers (Week 24)	25,600 (range: 6,400–204,800)	12,800 (range: 6,400–51,200)	400 (range: 0–3,200)
Median titers (Week 52)	51,200 (range: 12,800–102,400)	3,200 (range: 400–12,800)	200 (range: 0–6,400)
Median peak titers	204,800 (range: 51,200–409,600)	25,600 (range: 12,800–51,200)	800 (range: 0–12,800)
Time since ERT initiation	82 weeks (range: 24–130)	12 weeks (range: 8–24)	38 weeks (range: 8–172)
Seroconversion week	4 weeks (range: 4)	4 weeks (range: 4–8)	8 weeks (range: 4–64)
IOPD on ERT + TLD-MTX (n=14)
Groups	HSAT	SIT	LT
Percent	0	14.2% (n=2)	85.7% (n=12)2
Median titers (Week 12)	NA	IOPD13: 12,800; IOPD14: 25,600	1,600 (range: 0–12,800)
Median titers (Week 24)	NA	IOPD13: 12,800; IOPD14: 12,800	600 (range: 0–3,200)
Median titers (Week 52)	NA	IOPD13: 12,800	2503 (range: 0–800)
Median peak titers	NA	IOPD13: 51,200; IOPD14: 12,800	3,200 (range: <100–12,800)
Time since ERT initiation	NA	IOPD13: 7 weeks; IOPD14: 12 weeks	20.5 weeks (range: 4–93)
Seroconversion week	NA	IOPD13: 3 weeks; IOPD14: 8 weeks	6 weeks (range: 4–31)

HSAT, high and sustained antibody titers, SIT, sustained intermediate titers, LT, low titers, IOPD, infantile-onset Pompe disease, TLD-MTX, transient low-dose methotrexate, CRIM, cross-reactive immunological material, ERT, enzyme replacement therapy, NA, not applicable

¹All patients in ERT + TLD-MTX group and 35/37 patients in ERT monotherapy group seroconverted.

²One patient had peak titers of 12,800 twice (Week 5 and Week 12) on ERT but maintained low titers throughout, so was included in LT group.

³Patients who tested seropositive but had titers <100 were deemed to have a titer of 50.