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PubMed1981

Busulfan, antimetabolites, radiotherapy, and cost of treatment in chronic myelocytic leukemia. A non-controlled, non-randomized monocenter study with historical controls.

The possibilities were studied of achieving remission more quickly, of preventing conceivably alkylator-induced blastic transformation, and of prolonging survival in chronic myelocytic leukemia (CML) by replacing busulfan induction of remission by antimetabolite induction. The promise of the project was not considered to merit a prospective, controlled, randomized multicenter study, and therefore a retrospective, non-controlled, non-randomized pilot study was elected. One antimetabolite-treated group (cytosine arabinoside and thioguanine) and two busulfan-treated patient groups were studied. One of the latter two groups received splenic irradiation in addition to busulfan. No statistically significant differences between the busulfan groups were found in the time to achieve remission, the length of the first, unmaintained remission, the frequency of blastic metamorphosis or the cost of treatment. The actuarial survival curves of all three groups were similar. The antimetabolite induction was well tolerated and led to a statistically significantly more rapid remission than busulfan. However, the remission was significantly shorter, and no significant difference in the frequency of blastic metamorphosis was found between the groups. The median cost (from diagnosis to death) of hospitalization, visits, treatment, and part of the loss of production was approximately 106 000 Sw. cr. in the busulfan + radiotherapy group, 116 000 in the busulfan group, and 178 000 in the antimetabolite group. It is suggested that a prospective, randomized, controlled study could confirm that the present antimetabolite induction may lead to a more rapid remission induction in CML without more side-effects. However, to prevent early relapse, antimetabolite induction should be combined with busulfan maintenance treatment.

Busulfan↗

PubMed1998

Occlusive ligature and standardized fenestration of a Baerveldt tube with and without antimetabolites for early postoperative intraocular pressure control.

OBJECTIVE: To determine the effectiveness of a surgical modification for a nonvalved aqueous tube shunt in controlling intraocular pressure (IOP) in the early postoperative period. The effect of antimetabolite use on IOP also was studied. DESIGN: A retrospective study of consecutive patients who underwent modified Baerveldt 350-mm2 implant with varied, nonrandomized, exposure to antimetabolites. PARTICIPANTS: Fifty-one eyes of 46 patients with uncontrolled glaucoma were examined. INTERVENTION: Identical surgical modification of a Baerveldt 350-mm2 tube was performed in all cases and consisted of placement of an occlusive 7-0 polyglactin suture just anterior to the plate followed by a through-and-through penetration of the tube just anterior to the occlusive ligature with a standardized 15 degrees blade. Seventeen eyes were not exposed to antimetabolite, while 2 groups of 17 eyes had 3 minutes' episcleral exposure to either 5-fluorouracil 50 mg/ml or mitomycin C 0.4 mg/ml at the location corresponding to the fenestration. The Tenon's layer and conjunctiva were not exposed because of concerns regarding conjunctival erosion over the device. MAIN OUTCOME MEASURE: Intraocular pressure and number of antiglaucoma medications required were analyzed. RESULTS: For the group, mean IOP before surgery and on postoperative days 1, 4, 10, 21, 42, 63, 84, and 112 was (in millimeters of mercury) 34.6, 20.1, 17.0, 17.2, 22.0, 17.3, 18.7, 17.4, and 15.6, respectively. There was an elevation of IOP at day 21 relative to fibrotic blockage of the fenestration before suture autolysis. This was temporized with antiglaucoma medication until suture autolysis occurred or treated with laser suture lysis (8 eyes). On day 1, hypotony occurred in 3 (6%) eyes whereas IOP greater than 30 mmHg was observed in 13 (26%) eyes. By day 10, the frequency had decreased to one (2.1 %) eye and three (6.4%) eyes, respectively. The use of antimetabolites did not result in lower IOP or less medication needed for any group at any interval (analysis of variance). CONCLUSION: This modification of a nonvalved glaucoma tube shunt device provides adequate IOP control in the early postoperative period with a low rate of hypotony and surgical complications. If elevation of IOP occurs before suture autolysis, it generally is well controlled by antiglaucoma medications or laser suture lysis. Antimetabolite exposure did not influence early postoperative IOP in this study.

Aged↗

PubMed1976

[Search for antibiotic antimetabolites].

Special media have been developed during the past years, which provided detection of new antibiotics with the properties of antimetabolites produced by microorganisms. Antimetabolites of amino acids, vitamins and nucleic acids were found among the antimetabolite antibiotics. The antimetabolites of nucleic acids with an antitumor activity were most interesting. This group of the compounds included 5-asacytidin and antibiotic 1719 identical to azotomycin.

Actinomycetales↗

PubMed1997

Successful treatment of relapsed infant acute lymphoblastic leukemia with intensive antimetabolite-based chemotherapy.

PURPOSE: The treatment of infant acute lymphoblastic leukemia (ALL) continues to be a significant challenge for pediatric oncologists due to the high incidence of early relapses. Salvage regimens used to date have met limited success. We describe two cases of relapsed infant ALL who have achieved long-term survival with an intensive antimetabolite-based salvage regimen. PATIENTS AND METHODS: Two consecutive infants with relapsed ALL presented at our institution and were treated with an antimetabolite-based regimen. Both cases exhibited clinical and biological phenotypes previously associated with infantile ALL. RESULTS: Both patients have achieved prolonged and sustained remissions 48 and 30 months EFS respectively following therapy with intensive antimetabolite-based salvage regimen. CONCLUSIONS: An intensive multiagent antimetabolite based salvage regimen resulted in prolonged EFS in two cases of relapsed infant ALL. Dose intensification was achieved by administering repeated cycles of the same treatment schema using high dose chemotherapy throughout therapy. These infants were spared prophylactic cranial irradiation without a negative impact on outcome. The use of L-asparaginase, timed after high-dose Cytarabine (ARA-C) throughout therapy, might have contributed to their cure.

Antimetabolites, Antineoplastic↗

PubMed1999

Effects of antimetabolite induced cellular growth arrest on fibroblast-fibroblast interactions.

The use of single five-minute applications of antimetabolites during glaucoma filtration surgery has significantly reduced the occurrence of post-operative scarring and bleb failure. However, surgery for some patients is still unsuccessful, despite the use of antiproliferative agents, due to formation of scar tissue at the drainage site. It is not known if cells growth arrested in the treated area with a single application of antimetabolites influence the activity of adjacent non-treated cells. We hypothesise that the activity of non-treated cells recruited to the wound site may be involved in post-operative scarring. The aim of this study was to investigate the effects of antimetabolite induced cellular growth arrest on cell-cell interactions using in vitro techniques.Tenon's capsule fibroblast cultures were growth arrested by exposure for 5 minutes to mitomycin-C (0.001, 0.01 and 0.1 mg ml-1), 5-fluorouracil (0.25, 2.5 and 25 mg ml-1) or phosphate buffered saline (PBS). Following a period of serum-starvation, conditioned media (CM) were subsequently collected from the cells at intervals up to 29 days post-treatment. Correction for cell number was made prior to supplementation of serum-free medium with CM. CM were assessed for ability to support or inhibit normal non-treated fibroblast proliferation, migration and collagen contraction. Conditioned media collected from cells growth arrested with MMC or 5FU stimulated normal fibroblast proliferation, migration and collagen contraction in excess of non-conditioned serum-free medium. Peaks of fibroblast activity in CM differed according to which drug and concentration had originally been given to the treated cells. This study has demonstrated that CM collected from fibroblasts treated for 5 minutes with a range of concentrations of antimetabolites can differentially influence normal non-treated fibroblast activity. This in vitro data suggests that despite entering growth arrest, fibroblasts may still influence the behaviour of other cells via soluble mediators. They may have implications in the clinical setting, in that it may not be sufficient to suppress proliferation alone to prevent fibroblast behaviour associated with scarring after glaucoma filtration surgery.

Antimetabolites↗

PubMed2006

Review of consecutive phacotrabeculectomies supplemented with early needle revision and antimetabolites.

BACKGROUND: To describe the results of a novel postoperative management approach for patients undergoing combined cataract and glaucoma surgery supplemented with early needle revision and antimetabolites. METHODS: Consecutive retrospective chart review identified 66 patients who had undergone combined cataract and glaucoma surgery with early needling and antimetabolite injections between January 2002 and May 2003; 8 patients were excluded from analysis because of missing data or inadequate follow-up time. Single-site phacotrabeculectomy was performed followed by subconjunctival antimetabolite injections of 5-fluorouracil (5-FU). Needling was performed as an office procedure if early evidence of subconjunctival scarring was observed 2-6 weeks after surgery. Additional subconjunctival 5-FU injections were administered after needling, and repeat needling was performed with 5-FU or mitomycin-C if subconjunctival scarring recurred. A complete success was defined as a reduction in intraocular pressure (IOP) to <18 mm Hg without the use of antiglaucoma medications or further surgical procedures to control IOP. The outcome was considered a qualified success when antiglaucoma medications were required to achieve the same result. RESULTS: The mean preoperative IOP was 21.9 (SD 6.3) mm Hg, and the mean postoperative IOP at 6 months was 13.0 (SD 6.7) mm Hg. The mean number of medications was reduced from 2.9 (SD 1.3) preoperatively to 0.5 (SD 0.9) postoperatively at 6 months. Needling was performed because of early evidence of subconjunctival scarring in 34 patients. The 6-month outcomes of 37 patients (64%) were a complete success and of 47 patients (81%) were a complete or qualified success. A longer follow-up of 10-23 months was attained in 25 of the 58 patients. At latest visit, the mean postoperative IOP of this group was 13.0 (SD 5.5) mm Hg, the mean number of postoperative medications was 0.7 (SD 1), and 21 of the 25 (84%) had achieved a complete or qualified success. The most common complication for all 58 patients was an early, self-limited postoperative wound leak that was unrelated to the needling intervention and was observed in 26 patients (45%). INTERPRETATION: Phacotrabeculectomy supplemented with early needle revision and antimetabolites may improve outcomes of combined cataract and glaucoma surgery.

Aged↗

PubMed1998

New antimetabolites in cancer chemotherapy and their clinical impact.

It is almost 50 years since antimetabolites were first found to have clinical antitumour activity, with Farber's discovery that aminopterin could cause remission in acute leukaemia. In the following 10 years, methotrexate, 6-mercaptopurine and 5-fluorouracil (5-FU) found their way into clinical practice. Subsequently, cytosine arabinoside was found to have activity in acute leukaemia, but, until recently, other significant developments have involved optimizing the efficacy of existing antimetabolites, including the use of leucovorin with methotrexate or 5-FU. Recently, new antimetabolites have become a fertile area for anti-cancer drug research. Gemcitabine (GEMZAR) has emerged as an important new agent in several tumour types, including pancreatic, non-small-cell lung, bladder, breast and ovarian cancers. Capecitabine is an intriguing new prodrug, offering tumour selectivity and prolonged tumour exposure to 5-FU. More potent thymidylate synthase inhibitors have also emerged; raltitrexed is now commercially available for the treatment of colorectal cancer. Others under development include LY231514, which has other sites of action, hence the acronym MTA (multi-targeted antifolate). A novel target is glycinamide ribonucleotide formyltransferase (GARFT) and LY309887 and AG2034 are undergoing clinical investigation as GARFT inhibitors. A critical element with LY309887 appears to be co-administration of folate. It seems entirely possible that several novel antimetabolites will establish themselves in clinical practice in future for the treatment of solid tumours.

Animals↗

PubMedDate not supplied

Correlation of nucleoside and nucleobase transporter gene expression with antimetabolite drug cytotoxicity.

Antimetabolite drugs that inhibit nucleic acid metabolism are widely used in cancer chemotherapy. Nucleoside and nucleobase transporters are important for the cellular uptake of nucleic acids and their corresponding anticancer analogue drugs. Thus, these transporters may play a role both in antimetabolite drug sensitivity, by mediating the uptake of nucleoside analogues, and in antimetabolite drug resistance, by mediating the uptake of endogenous nucleosides that may rescue cells from toxicity. Therefore, we examined the relation of the expression of nucleoside and nucleobase transporters to antimetabolite cytotoxicity. We measured the RNA levels of all eight known nucleoside and nucleobase transporters in 50 cell lines included in the National Cancer Institute's Anticancer Drug Screen panel. RNA levels of concentrative nucleoside transporters (CNTs), equilibrative nucleoside transporters (ENTs) and nucleobase transporters (NCBTs) were determined by quantitative RT-PCR using real-time fluorescence acquisition. This method was validated by measuring the expression of the MDR1 gene, and correlating our results with independently determined measurements of MDR1 RNA levels and protein function in these cell lines. We then correlated the pattern of RNA levels to the pattern of cytotoxicity of anticancer drugs in the NCI drug screen database using the COMPARE analysis. Several hypothesized relations between transporter gene expression and cytotoxicity, based upon known interactions between certain nucleoside analogues and transporter proteins, were not observed, suggesting that expression of individual transporters may not be a significant determinant of the cytotoxicity of these drugs. The most closely correlated drug cytotoxicity patterns to transporter gene expression patterns (where increased expression corresponds to increase sensitivity) included those between CNT1 and O6-methylguanine and between ENT2 and hydroxyurea. We also observed that p53 status influenced correlations between ENT1 transporter gene RNA levels and sensitivity to the drugs tiazafurin, AZQ and 3-deazauridine. One of three drugs identified by correlation of cytotoxicity patterns with ENT1 RNA levels, 3-deazauridine, inhibited uptake of the classic ENT1 substrate uridine, demonstrating a physical interaction between an identified drug and the transporter. These studies demonstrate that it is possible to correlate genetic information to functional databases to determine the influence of transport gene expression on drug sensitivity and to identify transporter-drug interactions.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed1994

Computer-assisted microscope analysis of morphonuclear modifications induced by anticancer antimetabolites in cell lines cultured in vitro.

An original method is proposed for the purpose of discriminating between antimetabolites exhibiting different operating mechanisms. The present work was carried out by means of the digital cell image analysis of Feulgen-stained nuclei cultured in the presence of different antimetabolites. We chose this method because it enables anticancer drug-induced effects to be studied at both morphonuclear and cell cycle levels in the same biological sample. The results show that all the antimetabolites had similar effects on the nuclear texture of the cells and on cell cycle parameters. Furthermore, the use of multivariate analyses made it possible to distinguish between different mechanisms of action among drugs belonging to the same class of antineoplastic, i.e. antimetabolite agents.

Animals↗

PubMed2001

The use of antimetabolites with trabeculectomy: a critical appraisal.

PURPOSE: To examine why most ophthalmologists routinely use mitomycin C or 5-fluorouracil (antimetabolites) in association with filtering surgery for glaucoma. METHODS: Critical analysis of seven medical, social and economic trends. RESULTS: The rapid acceptance of the adjunctive use of antimetabolites at the time of filtration surgery may be explained by reasons other than anticipated increase in the "success" of glaucoma surgery. CONCLUSION: The use of antimetabolites in conjuction with filtering glaucoma surgery may be at least partially a consequence of changing medical-social-economic factors, rather than solely a desire on the part of physicians to improve the "success" of glaucoma surgery. This may indicate a need to reevaluate the proper place of antimetabolites in association with filtration surgery.

Antimetabolites↗

PubMed2005

Is intraocular pressure in the early postoperative period predictive of antimetabolite-augmented filtration surgery success?

PURPOSE: To determine whether intraocular pressure (IOP) in the early postoperative period after trabeculectomy or combined phacoemulsification-trabeculectomy, augmented with antimetabolite, correlates with IOP at one year in surgeries considered to be successful at that time point. DESIGN: Retrospective case series. METHODS: A chart review of antimetabolite-augmented surgical procedures done by DJG and JBS between January 1994 and November 2000 identified 82 primary or secondary trabeculectomies and 53 combined phacoemulsification-trabeculectomies with at least one year of follow-up. The success rate for each surgical subgroup was calculated and IOP on postoperative days (POD +/- SD) 1, 7 (+/-2), 30 (+/-5), 90 (+/-10), and 180 (+/-20) was correlated with IOP at one year (POY 1, between month 12 and 15) using linear regression. IOP at each time point was compared among eyes that achieved success at one year with and without the use of IOP-lowering agents. RESULTS: Of the 82 eyes having undergone antimetabolite-augmented trabeculectomies and the 53 eyes having undergone combined surgeries with at least one year of follow-up, the surgical success rates at POY 1 were 87.8% (72 of 82 eyes) and 92.5% (49 of 53 eyes). Of these, 42 eyes (58.3%) from 39 patients in the trabeculectomy group and 27 eyes (55.1%) from 24 patients in the combined surgery group did not require glaucoma medications at one year postsurgically, and were considered complete surgical successes. Mean preoperative IOP mm Hg +/- SD was 26.0 +/- 8.5 for the trabeculectomy group and 18.2 +/- 4.5 for the phaco-trabeculectomy group. Postoperative IOP at POD 1, POD 7, POD 30, POD 90, POD 180, and POY 1 respectively for the eyes undergoing trabeculectomy were 13.9 +/- 10.4, 9.5 +/- 6.2, 12.0 +/- 5.5, 12.0 +/- 5.2, 12.8 +/- 5.9, and 12.1 +/- 4.3, and for the combined surgery group were 20.8 +/- 12.5, 9.7 +/- 5.7, 12.2 +/- 5.4, 11.1 +/- 3.4, 11.6 +/- 4.6, and 10.3 +/- 4.3. Intraocular pressure on postoperative day one correlated poorly with intraocular pressure at POY 1 for the trabeculectomy group (R2 = 0.0788), and not at all for the combined procedures group (R2 = 0.018). The correlation was slightly better for intraocular pressure at postoperative day 90 for the trabeculectomy group (R2 = 0.546), and at postoperative day 180 for the combined group (R2 = 0.37), but still rather low. Eyes requiring glaucoma medication use at POY 1 in the trabeculectomy group had higher (P < 0.009) intraocular pressure at POD 30 and at all subsequent visits than eyes not requiring these medications. Eyes requiring glaucoma medication use at POY 1 in the phaco-trabeculectomy group had higher (P < 0.0025) intraocular pressure at POD 30, POD 180, and POY 1 than eyes not requiring these medications. CONCLUSION: Intraocular pressure in the early postoperative period correlates very poorly with intraocular pressure one year after successful antimetabolite-augmented trabeculectomy or combined cataract extraction and trabeculectomy. Starting one month after glaucoma surgery, intraocular pressure is substantially lower in eyes that will ultimately not require the use of ocular hypotensive agents to achieve clinical success one year postoperatively.

Aged↗

PubMed1999

Risk factors for failures of trabeculectomies performed without antimetabolites.

AIMS: To assess the risk profile for the failure of trabeculectomies in a large group of patients who were selected to be operated on without the use of antimetabolites. This was done in an effort to find subgroups of patients who may not need antimetabolites for primary procedures. METHODS: Consecutive patients scheduled for routine trabeculectomies were operated during a 4 year period and were followed up for at least 6 months postoperatively. Patients were regularly examined in the glaucoma unit and by their local ophthalmologists. Pre- and postoperative data were evaluated and success rates determined. RESULTS: 709 eyes of 566 patients were operated on; 534 eyes of 534 patients (94.4%) were finally evaluated. The mean follow up was 27.9 (SD 13.6) months with a range of 6-62 months. Success rates for complete surgical success ranged from 59% in the best group with pigmentary dispersion syndrome to 0% in the worst group with neovascular glaucoma. Success rates of patients with POAG, pseudoexfoliation, chronic angle closure, pigmentary dispersion syndrome, and dysgenetic glaucoma were similar. Failure rates ranged from 11% in the best group (pseudoexfoliation) to 80% in the worst group (neovascular glaucoma). Failure rates were high in complicated forms of glaucoma such as traumatic (30%), buphthalmus (40%), and uveitic (50%). For repeat trabeculectomies, the failure rate was 49% (20 of 41 eyes). The mean time until failure ranged from 2.7 months (traumatic) to 15.5 months (pigmentary dispersion syndrome) and was 4.9 months for repeat trabeculectomies. CONCLUSION: Trabeculectomy performed in selected groups of patients has a favourable outcome without the use of antimetabolites. It may be possible to avoid antimetabolites in these groups of patients for primary procedures.

Adolescent↗

PubMed1999

A major review of antimetabolites in glaucoma therapy.

Antimetabolites have been used in combination with filtering surgery to improve surgical results for more than 10 years. Based on research published since the introduction of antimetabolites right up to date, we discuss the various forms of antimetabolites that have been used, including drugs and irradiation. Among the drugs used, mitomycin C and 5-fluorouracil are the most prominent. We discuss the background of these agents, the progress in the use of antimetabolites and the research done on these drugs. These agents have been used both intra-operatively and perioperatively. We discuss the indications for their use, their mode of action, the techniques of usage, their variations as well as the complications and the treatment of complications.

Antimetabolites↗

PubMed1985

7-Hydroxyguanine, a novel antimetabolite from a strain of Streptomyces purpurascens. II. Physico-chemical properties and structure determination.

The molecular formula of a new antimetabolite produced by Streptomyces purpurascens was determined to be C5H5N5O2 by elemental analysis, FD-MS and 13C NMR. Reduction of this antimetabolite with Raney nickel yielded guanine. The antimetabolite was distinguishable from known N-hydroxyguanines by comparison of their UV spectra. The structure of the antimetabolite was finally established to be 7-hydroxyguanine by X-ray crystallography.

Antimetabolites, Antineoplastic↗

PubMed1988

Interferon effects upon the adenocarcinoma 38 and HL-60 cell lines: antiproliferative responses and synergistic interactions with halogenated pyrimidine antimetabolites.

In order to gain insight into the mechanisms affecting combination treatment of tumor cells with interferon and halogenated pyrimidine antimetabolites, in vitro studies of murine colon adenocarcinoma 38 and HL-60 cell lines were undertaken. Interferons exhibited modest antiproliferative effects against these lines with DNA synthesis inhibited greater than RNA greater than protein synthesis, as studied by 3H-precursor incorporation. The adenocarcinoma cell line was considerably more sensitive to recombinant gamma-than to purified alpha/beta-interferon, while HL-60 was slightly more sensitive, in short term studies, to antiproliferative effects of recombinant alpha- than to gamma-interferon. Interferon treatment was further associated with suppression of a hyperdiploid component of the adenocarcinoma cell line, as detected by flow cytometry. Combination treatment of the adenocarcinoma cell line with interferon and halogenated pyrimidines, under 4-day continuous exposure conditions, revealed significant synergy for growth inhibition with gamma- much greater than alpha/beta-interferon and with 5-fluorodeoxyuridine greater than 5-fluorouracil much greater than 5-fluorouridine. Thus, synergy was much greater with the more antiproliferative interferon and with the antimetabolite derivative most likely to lead to thymidylate synthetase inhibition rather than RNA incorporation. Sequential 2-day + 2-day treatment revealed greater synergy when interferon preceded 5-fluorouracil or 5-fluorodeoxyuridine rather than the reverse protocol. The synergy of gamma-interferon and 5-fluorodeoxyuridine could be blocked by thymidine, which bypasses inhibition of thymidylate synthetase. HL-60 also exhibited thymidine antagonized synergistic growth-inhibitory effects of interferon and 5-fluorouracil. Analysis of this interaction by [3H]thymidine incorporation, which can reflect thymidylate synthase inhibition, revealed exaggerated responses of interferon-treated cells to either 5-fluorouracil or 5-fluorodeoxyuridine. These results indicate that interferon-halogenated pyrimidine antimetabolite synergistic interactions may be common to several cell types. Evidence is further presented for a mechanism of synergy entailing enhanced thymidylate synthetase inhibition by the antimetabolite of interferon-treated cells.

Adenocarcinoma↗

PubMed1988

Uptake of glutamine antimetabolites 6-diazo-5-oxo-L-norleucine (DON) and acivicin in sensitive and resistant tumor cell lines.

The uptake system for 6-diazo-5-oxo-L-norleucine (DON) was studied in mouse P388 leukemia cells. The DON transport system was found to resemble that of another glutamine antimetabolite, Acivicin, in its strong temperature dependence, utilization of the "L" transport system, inhibition by glutamine but not by glutamate, potent inhibition by p-chloromercuribenzene sulfonate, Na+, and only minimal inhibition by various energy poisons. A Km of approximately 70 microM and a Vmax of 3.4 nmoles/10(6) cells/min was calculated for this cell line. The accumulated DON was not metabolized by P388 cells and moderate efflux occurred at 37 degrees C. The DON transport characteristics of a DON-resistant P388 cell line (100 times ID50 of parent line) were similar to those of the DON-sensitive parent line, indicating that altered drug transport may not be involved in development of resistance to this antimetabolite. The finding that an Acivicin-resistant subline of P388 cells which exhibited good transport of DON showed negligible transport of Acivicin suggests different modes of resistance towards the two glutamine antimetabolites.

Animals↗

PubMed1983

Optimum scheduling during combination chemotherapy of murine leukemia. Additional examples of schedule-dependent synergism between S-phase-specific antimetabolites and agents inducing mitotic or pre-mitotic (G2) arrest.

In an extension of our prior studies with methotrexate and vinca alkaloids, three additional drug combinations incorporating an S-phase-specific antimetabolite and an agent inducing blockade at mitosis or G2 were found to exhibit potent schedule-dependent synergism against the L1210 leukemia. Combinations employed include cytosine arabinoside with vindesine and methotrexate with teniposide (VM-26) or the -deaza-pteridine derivative, NSC 181,928. Synergism was observed following sequential administration (antimetabolite given 24 h before the second agent), but effects following simultaneous administration or sequential administration in the reverse order (antimetabolite given 24 h after the second agent) were only additive.

Animals↗

PubMed1989

Potentiation of antimetabolite antitumor activity in vivo by dipyridamole and amphotericin B.

Previous studies have shown that dipyridamole (DP), a potent nucleoside transport inhibitor blocking the rescue effect of exogenous nucleosides, markedly potentiates the cytotoxicity of antimetabolites. However, no enhancement of the chemotherapeutic effect of antimetabolites by DP in vivo has yet been reported. This study provided evidence that the combination of DP and amphotericin B (AmB) significantly potentiated the inhibitory effect of 5-fluorouracil (FU) or methotrexate (MTX) against a panel of transplantable tumors including sarcoma 180, cervical carcinoma U14, and Lewis lung carcinoma in mice. No significant increase in toxicity was induced by this combination in treated mice. Our results indicate that the combination of DP and AmB with antimetabolites is potentially useful in cancer chemotherapy.

Amphotericin B↗