Genetic Toxicology - Mammalian Cell Mutagenicity

Study Information
Study Attribute	Value
CEBS Accession Number:	002-01933-0006-0000-4
Chemical Name:	Cytarabine hydrochloride
CASRN:	69-74-9
NTP Study Type:	Genetic Toxicology - Mammalian Cell Mutagenicity
NTP Study ID:	105521
Study Result:	Positive

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Table Instructions and Notes:
Studies are indicated to be "Nontoxic" when the observed reductions in relative total growth did not indicate that the maximum tolerated dose was achieved.

Nonactivation Trial: 1 Experiment Call: Positive
		Conc. ug/mL	Cloning Efficiency	Relative Total Growth	Mutant Colonies	Mutant Frequency	Avg Mutant Frequency
Vehicle Control	Fischer Medium	0	88	84	68	26	31
			90	104	79	29
			80	108	89	37
			70	103	68	32
Test Chemical	Cytarabine hydrochloride	5	61	10	908	500	493*
			49	10	708	487	493*
		10	53	10	777	487	529*
			49	9	846	572	529*
		20	42	7	601	473	438*
			55	9	669	403	438*
		40	16	2	403	857	766*
			21	3	425	675	766*
		80	11	1	321	944
			7r	1	258	1259
Positive Control	Methyl Methane Sulfonate	15	35	27	188	181	186*
Positive Control			33	23	187	191	186*

Nonactivation Trial: 2 Experiment Call: Positive
		Conc. ug/mL	Cloning Efficiency	Relative Total Growth	Mutant Colonies	Mutant Frequency	Avg Mutant Frequency
Vehicle Control	Fischer Medium	0	66	92	66	34	32
			69	113	84	41
			67	106	57	28
			64	90	50	26
Test Chemical	Cytarabine hydrochloride	5	38	9	948	828	796*
			42	9	951	764	796*
		10	38	5	795	691	799*
			38	6	1042	906	799*
		20	27	3	441	538	547*
			27	4	450	556	547*
		40	10	1	190	633	626*
			20	2	377	618	626*
		60	14	1	926	2286	2412*
			11	1	812	2537	2412*
		80

Positive Control	Methyl Methane Sulfonate	15	32	27	88	91	120*
Positive Control			35	22	156	149	120*

Nonactivation Trial: 3 Experiment Call: Positive
		Conc. ug/mL	Cloning Efficiency	Relative Total Growth	Mutant Colonies	Mutant Frequency	Avg Mutant Frequency
Vehicle Control	Fischer Medium	0	52	85	56	36	36
			54	100	55	34
			53	108	47	30
			52	108	72	46
Test Chemical	Cytarabine hydrochloride	0.16	50	103	52	35	41
			47	105	66	47	41
		0.31	67	101	66	33	40
			59	80	85	48	40
		0.63	56	75	90	54	53
			61	85	94	52	53
		1.25	53	65	196	124	130*
			57	62	231	136	130*
		2.5	38	20	468	412	410*
			44	21	532	408	410*
		5	39	9	841	728	718*
			40	9	838	707	718*
Positive Control	Methyl Methane Sulfonate	15	12	12	113	323	304*
Positive Control			13	14	108	284	304*

Nonactivation Trial: 4 Experiment Call: Positive
		Conc. ug/mL	Cloning Efficiency	Relative Total Growth	Mutant Colonies	Mutant Frequency	Avg Mutant Frequency
Vehicle Control	Fischer Medium	0	84	92	133	53	48
			86	108	120	47
			88	93	132	50
			94	106	117	42
Test Chemical	Cytarabine hydrochloride	0.31	80	85	138	58	60
			101	86	189	63	60
		0.63	108	76	224	69	67
			102	66	198	65	67
		1.25	86	59	453	176	186*
			91	55	536	197	186*
		2.5	54	17	769	473	423*
			61	18	677	373	423*
		5	39	2	1125	966	1003*
			41	3	1269	1040	1003*
Positive Control	Methyl Methane Sulfonate	15	29	18	384	439	444*
Positive Control			33	24	437	448	444*

Nonactivation Trial: 5 Experiment Call:
		Conc. ug/mL	Cloning Efficiency	Relative Total Growth	Mutant Colonies	Mutant Frequency	Avg Mutant Frequency
Vehicle Control	Fischer Medium	0	106	109	42	13	20
			77	106	64	28
			83	103	35	14
			71	82	55	26
Test Chemical	Cytarabine hydrochloride	0.125	56	84	49	29	26
			87	85	58	22	26
		0.25	83	63	66	27	40*
			82	63	133	54	40*
		0.5	57	47	263	155	143*
			69	45	272	131	143*
		1	52	17	467	301	335*
			48	13	528	369	335*
		2	43	6	751	589	590*
			45#	6	798	591	590*
		4	30	2	440	492	480*
			32#	2	442	468	480*
Positive Control	Methyl Methane Sulfonate	15	22	19	147	223	196*
Positive Control			40	26	200	169	196*

Nonactivation Trial: 6 Experiment Call:
		Conc. ug/mL	Cloning Efficiency	Relative Total Growth	Mutant Colonies	Mutant Frequency	Avg Mutant Frequency
Vehicle Control	Fischer Medium	0	55	98	48	29	23
			66	106	43	22
			63	97	44	23
			55#	98	30	18
Test Chemical	Cytarabine hydrochloride	0.0125	88#	128	41	16	17
			92#	131	52	19	17
		0.025	78	118	56	24	19
			92	150	40	14	19
		0.05	69	115	50	24	19
			67#	110	28	14	19
		0.1	91	103	49	18	17
			107#	117	54	17	17
		0.2	77	113	52	22	24
			75	103	58	26	24
		0.4	100	93	122	41	42*
			94	92	121	43	42*
Positive Control	Methyl Methane Sulfonate	15	36	26	136	125	137*
Positive Control			30	24	136	149	137*

Footnotes:
Asterisks(*) indicate significant responses.
r = rejected value due to quality control criteria
# = reduced sample size because of the loss of one culture dish due to contamination