British journal of cancer
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British journal of cancer · Dec 1995
Plasma clearance of an antibody--enzyme conjugate in ADEPT by monoclonal anti-enzyme: its effect on prodrug activation in vivo.
The effect of anti-enzyme antibody clearance on prodrug turnover in antibody-directed enzyme prodrug therapy (ADEPT) has been studied. Mice bearing LS174T xenografts were given localising carboxypeptidase G2 (CPG)2 conjugate (AEC) and 19 h later galactosylated anti-CPG2 antibody (SB43-GAL). In regimen I prodrug was injected 5 h after SB43-GAL as previously described. ⋯ Residual prodrug in tumour was unaffected by SB43-GAL, showing the advantage of galactosylation in minimising inactivation of CPG2 in tumour. By contrast, residual prodrug in blood persisted for longer when SB43-GAL was used. Circulatory clearance of enzyme with SB43-GAL allows prodrug to be administered expediently with reduced toxicity and with the prospect of increasing the dosage.
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British journal of cancer · Nov 1995
Anti-tumour effects of an antibody-carboxypeptidase G2 conjugate in combination with phenol mustard prodrugs.
ADEPT is an antibody-based targeting strategy for the treatment of cancer. We have developed two new prodrugs, 4-[N,N-bis(2-chloroethyl)amino]-phenoxycarbonyl-L- glutamic acid (PGP) and (S)-2-[N-[4-[N,N-bis(2-chloroethyl)amino]- phenoxycarbonyl]amino]-4-(5-tetrazoyl)butyric acid (PTP), which are cleaved by the bacterial enzyme CPG2 to release the 4-[N,N-bis(2-chloroethyl)amino] phenol drug. In vitro, both prodrugs are approximately 100- to 200-fold less potent than the parent drug (1 h IC50 = 1.4 microM) in LoVo colorectal tumour cells. ⋯ Administration of either prodrug, at doses which cause 6-8% body weight loss, 72 h after administration of the A5B7-CPG2 conjugate to the LoVo tumour-bearing mice resulted in tumour regressions and growth delays of 14-28 days. The PTP prodrug in combination with a high dose of conjugate (10 mg kg-1) gave the best anti-tumour activity despite being a 10-fold worse substrate for CPG2 than PGP. Prodrug alone, active drug alone or prodrug in combination with a non-specific conjugate had minimal anti-tumour activity in this tumour model.
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British journal of cancer · Nov 1995
Clinical TrialIntrapleural administration of interleukin 2 in pleural mesothelioma: a phase I-II study.
Twenty-three patients with pleural mesothelioma stage I-IIA were entered in a study of continuous daily intrapleural infusion of interleukin 2 (IL-2) for 14 days, repeated every 4 weeks. IL-2 was administered according to a groupwise dose escalation schedule (group A, 3 x 10(4); group B, 3 x 10(5); group C, 3 x 10(6); group D, 6 x 10(6); group E, 18 x 10(6); and group F, 36 x 10(6) IU day-1). Each group consisted of at least three patients. ⋯ In view of the refractory nature of the disease IL-2 may be a treatment option for mesothelioma. A formal phase II study is warranted. Based on the observed toxicity, the lack of dose-response relationship and the immunomodulatory effects seen at relatively low-dose IL-2, the recommended dose for a phase II study is 3 x 10(6) IU day-1 using the present treatment schedule.
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British journal of cancer · Aug 1995
Characterisation of a human small-cell lung cancer cell line resistant to the DNA topoisomerase I-directed drug topotecan.
Camptothecins are DNA topoisomerase I-directed anti-tumour drugs with a novel mechanism of action. Topotecan (TPT), a hydrophilic derivative of camptothecin, is currently undergoing phase II clinical trials in small-cell lung cancer (SCLC). Human SCLC OC-NYH cells were made more than 6-fold resistant to topotecan by stepwise drug exposure and resistance was stable for 70 passages without drug. ⋯ Accordingly, the topoisomerase II-directed drug etoposide (VP-16) induced an increased number of DNA single-strand breaks in NYH/TPT cells. However, sensitivity to different topoisomerase II-targeting agents in NYH/TPT cells varied from increased to decreased, indicating a role for as yet unidentified factors acting on the pathway to cell death after topoisomerase II-induced DNA damage has occurred. Of 20 anti-cancer agents tested, only hydroxyurea showed marked collateral hypersensitivity in NYH/TPT cells.
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British journal of cancer · Jul 1995
AQ4N: an alkylaminoanthraquinone N-oxide showing bioreductive potential and positive interaction with radiation in vivo.
AQ4N (1,4-bis([2-(dimethylamino-N-oxide)ethyl]amino)5,8-dihydroxy- anthracene-9,10-dione) is a novel alkylaminoanthraquinone N-oxide which, on reduction, forms a stable DNA affinic cytotoxic compound AQ4. The in vivo anti-tumour efficacy of AQ4N was investigated in B6D2F1 mice bearing the T50/80 mammary carcinoma. The effect of the drug was evaluated in combination with hypobaric hypoxia and with radiation (single and multiple fractions). ⋯ This was obtained even if the drug was administered from 4 days before to 6 h after radiation treatment. Equivalent anti-tumour activity was also shown when both AQ4N (200 mg kg-1) and radiation (5 x 3 Gy) were administered in fractionated schedules. In conclusion, AQ4N shows significant potential as a bioreductive drug for combination with fractionated radiotherapy.