March, 1963
201
Notes Hydroxyurea. A New Type of Potential Antitumor Agent BARBARA STEARNS, KATHRYN A. LOSEE,A N D JACK BERXSTEIN The Squibb Institute f o r Medical Research, New Brunswick, X. J . Received October 21, 1968
Previous investigations in our laboratories with derivatives of hydroxylamine, including the cyclic hydroxamic acids, led to a number of potent antibacterial and antifungal agents.2 To continue our study of the structure-activity relationships in this series we had prepared hydroxyurea3 and related compounds. I n spite of the previous reports that hydroxyurea was ineffective in RC mouse mammary carcinoma4 and Sarcoma 180,5 me have investigated hydroxyurea in leukemia, since it had been reported to alter leukocyte formation by bone marrow in experimental animalse6 Screening results now have shown that hydroxyurea itself is effective against the standard L 1210 leukemia in mice upon intraperitoneal or oral administration and typical dose responses are given in Table I. I n addiTABLE I AKTILEUKEMICACTIOXOF HYDROXYUREA 05. L 1210" Dose in mg./kg.
Average at. change of rnicec
Average life span
70Increas? in life spand
ISTRAPERITONEAL~
25 50 100 200 100 Controls
$0 3 -0 5 -1 3 -1 1 -1 0 $2.2
10 13 24 12 16 8
7 0 3 3 2 1
32 60 76 51 100
OR 4L
39 175 -1 2 12 8 250 -0 9 14 4 56 400 -1.0 16.4 i8 600 -1.8 I5.i 70 Controls +1.4 9.2 a Groups of 10 mice were given 1,000,000 leukemic cells by intraperitoneal injection 24 hr. prior to initiation of therapy. Grouas of 10 mice were treated bv intraDeritonea1 iniection once a- day for the duration of 1ife"or 15 'days (whichever is shorter). Animals weighed on 7th day after leukemic inoculation. * An increase in life span of 25%) over control animal is significant,
'
(1) The biological d a t a reported here were obtained a t the screening laboratories of t h e Cancer Chemotherapy Sational Service Center, National Cancer Institute, National Institutes of Health. 12) E. Shaw. J. Bernstein, K. Losee, and R. A. Lott, J. Am. Chem. Sac., 72, 4362 (1950). 13) I n this paper, t h e name hydroxyurea is used t o denote the compound NHzCONHOH, m.p. 145-146O dee. T h e so-called low melting isomer (m.p. 72') of hydroxyurea has been shown t o be 0-carbamoylhydroxylaminc: hl. Davies a n d N. A. Spiers, Spectrochim. Acta, 487 (1989); H. Kofod, Acta Chem. Scand.. 13, 461 (1959); see also 0 . Exner, ref. 8. (4) 0. S. Tarnowski and C. C. Stock, Cancer Research, 18, No. 8. P a r t 2, Compound 6878. ( 5 ) C. C. Stock, D. A. Clarke, F. S. Philips, R. K. Barclay, and S. A. Myron, i b i d . , 20, No. 5 , P a r t 2. Compound 19968. (6) F. Rosenthal, L. Wislicki and L. Koller. Klin. lf'ochschr., 7 , 972 (1928).
tion, preliminary tests indicate that upon intraperitoneal administration hydroxyurea is active against a variety of other leukemias, being effective against L 1210 strains resistant to amethopterin, 2-amino-Bpurinethiol or 8-azaguanine. On the other hand, it shows only slight activity against L 5178Y-h leukemia and marginal activity against a 5-fluorouracil-resistant leukemia P 815/Fu-A. I n the preliminary screening it has not shown activity against L 1210 leukemia resistant to 6-mercaptopurine. These results are summarized in Table 11. It is also of interest that hydroxyTABLEI1 ASTILEUKEMIC ACTION O F HYDROXYUREA AT 100 See Table I for explanation of footnotes
XG./KG.h
Arerape life span
Average w t . change of miceC
7cIncreased in
ConStrain5
L L L L L L L
Treated
trols
0 -0 2 $0.6 -0.5 0 $1.6 +0.8
$1.3
1210 1210/8-AG-A 1210/Ameth-A 1210/6-MP-A 1210/6-TG-A 5178Y-A
P815/Fu-A
f2
1
$2.2 +2.2 +27 $3.8 $2.0
Treated
Controls
13.9 18.9 16.6 25.7 29.1 17.0 16.5
8.9 13.2 9.7 21.9 15.7 12 3 13.4
life span
56 43
i1 li
85 38 23
urea is active against the solid tumor, LB 82T leukemia, since at a dose of 100 mg./kg. it causes a 91% inhibition of tumor growth in mice. I n view of these results with hydroxyurea itself, a number of analogs and derivatives have been prepared. Alkyl derivatives were synthesized by the reaction of a hydroxylamine with potassium cyanate (A) or an alkyl isocyanate (B).' Acyl derivatives mere prepared by treatment of hydroxyurea with an acylating agent (C)x or by the reaction of an acyl isocyanate with a hydroxylamine (D). g A detailed description of these (A) RSHOH
(B) R'XHOH
-HCNO
RNCO
-+
(C) HJTCONHOH (D) R'CONCO
H2NCOXROH
RXHCOXR'OH
(RC0)zO
----+
H2NCOXHOCOR
RNHOH
-+
R'COXHCOSROH
syntheses and the properties of the compounds prepared, as well as the results of the antitumor screening, mill be published shortly. On the basis of the screening results hydroxyurea'O has been selected for clinical evaluation in the treatment of leukemia. (7) L. Francesooni and A. Parroozani, Qazs. Chim. Ital., 31, 11. 343 (1901). (8) 0. Exner, Collection Czech. Chem. Commun., 2 2 , 333 (1957). 19) TV. A. Lott J. Bernstein and B. Stearns, U. S. Patent 2,989,110 (1961); Chem. Abstr, 66, 7213 (1962). (10) HydreaD.
