Yttrium-90 ibritumomab tiuxetan consolidation versus rituximab maintenance therapy after induction chemotherapy in patients with indolent non-Hodgkin lymphoma: a single-institution experience

Figures & data

Table 1. Patient characteristics at study entry.

Parameters	^90Y-IT consolidation	R maintenance	p value^a
	n = 27	n = 48
Patient age, years, median (range)	67 (45–86)	65.5 (43–89)	0.711
Sex, male/female	15 / 12	28 / 20	0.335
Stage at diagnosis, n (%)			0.775
I/II	7 (26)	10 (21)
III/IV	20 (74)	38 (79)
Performance status, n (%)			> 0.99
0	26 (96)	46 (96)
1	1 (4)	2 (4)
Histopathology, n (%)			0.341
Follicular, grade 1–2	13 (48)	24 (50)
Follicular, grade 3a	4 (15)	5 (10)
NMZL	7 (26)	13 (27)
LPL	0 (0)	4 (9)
SLL	2 (7)	0 (0)
Low-grade B-cell lymphoma, NOS	1 (4)	2 (4)
Bone marrow involvement, n (%)			0.465
Negative	13 (48)	18 (38)
Positive	14 (52)	30 (62)
Maximal tumor size, n (%)			0.158
0 cm	11 (41)	28 (58)
0.1 to ≤5 cm	16 (59)	20 (42)
Response to induction therapy, n (%)			0.158
CR	11 (41)	28 (58)
PR	16 (59)	20 (42)
LDH level, n (%)			> 0.99
≤Normal upper limit	24 (89)	41 (85)
> Normal upper limit	3 (11)	7 (15)
sIL2R level, n (%)			0.309
≤Normal upper limit	25 (93)	39 (81)
> Normal upper limit	2 (7)	9 (19)
Induction chemotherapy, n (%)			0.126
R-Bendamustine	7 (26)	3 (6)
R -CHOP	7 (26)	18 (38)
R-CVP	8 (31)	15 (31)
R alone	5 (19)	12 (25)

Abbreviations: 90Y-IT, yttrium 90-ibritumomab tiuxetan; R, rituximab; MCL, mantle cell lymphoma; CR, complete response; PR, partial response; CHOP, cyclophosphamide, doxorubicin, vincristine, prednisone; CVP, cyclophosphamide, vincristine, prednisone; LDH, lactate dehydrogenase; sIL-2R, soluble interleukin-2 receptor; NOS, not otherwise specified. ^aFisher's exact test.

Figure 1. Progression-free survival (A), time to next treatment (B), and overall survival (C) after post-remission treatment. Abbreviations: Yttrium-90 ibritumomab tiuxetan consolidation, red line; rituximab maintenance, dark blue line. ⁹⁰Y-IT, yttrium-90 ibritumomab tiuxetan.

Table 2. Outcomes after 90Y-ibritumomab tiuxetan consolidation and rituximab maintenance.

Parameters		^90Y-IT consolidation	R maintenance
		n = 27	n = 48	p value
Response
ORR (CR+PR)	n	26	43	0.410^a
ORR (CR+PR), %, (95% CI)		96 (81–100)	90 (77–97)
CR	n	21	34	0.179^a
CR rate, %, (95% CI)		78 (58–91)	71 (56–83)
PR	n	5	9
PR rate, %, (95% CI)		18 (6–38)	19 (9–33)
SD	n	1	0
SD rate, %, (95% CI)		4 (0–19)	0 (0–6)
PD	n	0	5
PD rate,, %, (95% CI)		0 (0–11)	10 (4–23)
Progression-free survival, 5 years, %		75.5	82.4	0.839^b
%, 95% CI		48.9–89.5	65.1–91.6
TTNT		NR	NR	0.804^b
%, 95% CI		NR-NR	NR-NR
Overall survival (5 years, %)		100	97.8	0.465^b
%, 95% CI		100–100	85.3–99.7

Abbreviations: 90Y-IT, yttrium 90-ibritumomab tiuxetan; R, rituximab; ORR, overall response rate; CI, confidence interval; CR, complete response; PR, partial response; SD, stable disease; PD, progressive disease; TTNT, time to next treatment; NR, not reached.

^aFisher's exact test, ^bLog-rank test.

Figure 2. Disease response status conversion before and after yttrium-90 ibritumomab tiuxetan consolidation (left), or rituximab maintenance (right). Abbreviations: ⁹⁰Y-IT, yttrium-90 ibritumomab tiuxetan; R maintenance, rituximab maintenance; CR, complete response; PR, partial response; SD, stable disease; PD, progressive disease.

Table 3. 5-year PFS with 90Y-ibritumomab tiuxetan consolidation versus rituximab maintenance according to subgroup.

Factors		n		5-year PFS (%, 95% CI)		p value^a
		^90Y-IT consolidation	R maintenance	^90Y-IT consolidation	R maintenance
Age:	< 65 years	12	22	88.9 (43.3–98.4)	79.7 (53.7–92.1)	0.331
	≥ 65 years	15	26	72.2 (53.9–85.4)	77.6 (66.2–95.8)	0.580
Sex:	Female	12	20	90.0 (47.3–98.5)	81.7 (55.7–93.3)	0.631
	Male	15	28	74.6 (38.4–85.9)	83.7 (57.4–94.5)	0.656
Histopathology:	Follicular lymphoma	17	29	86.5 (55.8–96.5)	75.3 (51.3–88.7)	0.322
	Others	10	19	80.0 (66.4–86.5)	94.1 (65.0–99.1)	0.606
Stage:	I/II	7	9	88.6 (21.3–91.2)	100	0.656
	III/IV	20	38	76.7 (41.2–92.4)	77.9 (57.5–89.3)	0.583
Bone marrow involvement:	Positive	14	30	91.7 (53.9–98.8)	79.3 (55.4–91.3)	0.326
	Negative	13	18	82.2 (46.3–84.4)	88.9 (62.4–97.1)	0.535
Disease status at the start	PR	16	20	84.7 (59.7–94.8)	57.7 (37.0–84.3)	0.115
of post-remission treatment:	CR	11	28	90.0 (47.3–98.5)	82.1 (57.7–93.1)	0.471

Abbreviations: PFS, progression-free survival; ⁹⁰Y-IT, yttrium 90-ibritumomab tiuxetan; R, rituximab; CI, confidence interval; PR, partial response; CR, complete response.

^aLog-rank test.

Table 4. Adverse events of 90Y-ibritumomab tiuxetan consolidation and rituximab maintenance.

	^90Y-IT consolidation (n = 27)		R maintenance (n = 48)
	Any grade	Grade 3–4	Any grade	Grade 3–4
	no. of patients (%)		no. of patients (%)
Any event	27 (100)	20 (74)	9 (19)	2 (4)
Hematologic
Neutropenia	25 (94)	22 (81)	7 (15)	2 (4)
Anemia	18 (67)	0	2 (4)	1 (2)
Thrombocytopenia	27 (100)	13 (48)	4 (8)	1 (2)
Non-hematologic
Fatigue	8 (30)	0	4 (8)	0
Infusion-related reaction	0	0	0	0
Asthma	0	0	1 (2)	0
Hypoproteinemia	7 (26)	0	8 (17)	0
Hypoalbuminemia	2 (7)	0	3 (6)	0
Increased bilirubin	0	0	1 (2)	0
Increased AST	5 (19)	0	6 (13)	0
Increased ALT	5 (19)	0	11 (23)	0
Increased ALP	7 (26)	0	5 (10)	0
Increased Cr	0	0	3 (6)	0
Hyperglycemia	3 (11)	0	4 (8)	0
Febrile neutropenia	1 (4)	1 (4)	0	0

Abbreviations: ⁹⁰Y-IT, yttrium 90-ibritumomab tiuxetan; R, rituximab; AST, aspartate aminotransferase; ALT, alanine aminotransferase; ALP, alkaline phosphatase; Cr, creatinine.