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Four patients with the hemolytic uremic syndrome secondary to mitomycin therapy were treated with intense plasmapheresis and antiplatelet agents. All four patients had a hematologic response and three had slow, but steady, improvement in renal function. These results suggest an important role for these agents in mitomycin-induced hemolytic uremic syndrome.
A new mitomycin C derivative, KW-2149, is known to form a covalent conjugate with human serum albumin (HSA). This conjugate exhibits 1/20 of the anticellular activity of unconjugated KW-2149. Structural studies of this conjugate were carried out using a combination of enzymatic digestion, high-performance liquid chromatography (HPLC), and matrix-assisted laser desorption/ionization (MALDI) mass spectrometry. The tryptic peptide T5 (residues 21-41) was the only peptide found to be modified by KW-2149 moieties, the [(gamma-L-glutamylamino)ethyl]thio group or the (2-aminoethyl)thio group, through a disulfide bond. Although the latter peptide lost its mitomycin C moiety in the course of tryptic digestion, these data strongly suggest that KW-2149 was bound to Cys-34, the only free cysteine on HSA.
Oligodeoxyribonucleotides cross-linked by reductively activated mitomycin C (MC) were prepared and purified for the first time. The cross-linked products were structurally characterized by nucleoside and MC-nucleoside adduct analysis. Optimal conditions were established for the cross-linking reaction, resulting in high yields, typically in the 20-50% range. Nuclease digests of the cross-linked oligonucleotides yielded the same bifunctional MC-deoxyguanosine adduct as that previously isolated from DNA exposed to MC in vitro and in vivo [Tomasz et al. (1987) Science 235, 1204]. The cross-linked oligonucleotides displayed broad thermal melting profiles, greatly increased Tm, and complex circular dichroism spectra. Phosphodiester linkages at the cross-link were resistant to spleen exonuclease, nuclease P1, and TaqI and ClaI restriction endonucleases; snake venom diesterase action was uninhibited. The cross-links are stable to heat at neutral pH but are removed by treatment in hot piperidine or by the reducing agents Na2S2O4 and dithiothreitol. Mechanisms are proposed for these reactions. These studies define optimal methods for introducing mitomycin cross-links into DNA fragments at a specific site, providing a versatile tool to study the effects of the MC cross-links on DNA structure and function.
Twenty-three new mitomycin C analogues designed to have increased metal complexing ability were synthesized and tested against P388 leukemia in mice. Their ability to complex Cu(II) was revealed by the shifts in their UV absorption spectra caused by this metal. One analogue was clearly more active than mitomycin C in the antitumor assay and two others had good activity. Correlation between antitumor activity and Cu(II) complexing ability was ambiguous. The most active compounds were either not complexers or they were complexers limited to the 2-(2-pyridyl)alkyl type substituent on N7. A variety of amino acid substituents on N7 showed only weak antitumor activity.
The three dimers 3, 4, and 5 of mitomycin C (MC), a natural antibiotic and cancer chemotherapeutic agent, were synthesized in which two MC molecules were linked with -(CH(2))(4)-, -(CH(2))(12)-, and -(CH(2))(3)N(CH(3))(CH(2))(3)- tethers, respectively. The dimeric mitomycins were designed to react as polyfunctional DNA alkylators, generating novel types of DNA damage. To test this design, their in vitro DNA alkylating and interstrand cross-linking (ICL) activities were studied in direct comparison with MC, which is itself an ICL agent. Evidence is presented that 3-5 multifunctionally alkylate and cross-link extracellular DNA and form DNA ICLs more efficiently than MC. Reductive activation, required for these activities, is catalyzed by the same reductases and chemical reductants that activate MC. Dimer 5, but not MC, cross-linked DNA under activation by low pH also. Sequence specificities of cross-linking of a 162-bp DNA fragment (tyrT DNA) by MC, 3, and 5 were determined using DPAGE. The dimers and MC cross-linked DNA with the same apparent CpG sequence specificity, but 5 exhibited much greater cross-linking efficacy than MC. Greatly enhanced regioselectivity of cross-linking to G.C rich regions by 5 relative to MC was observed, for which a mechanism unique to dimeric MCs is proposed. Covalent dG adducts of 5 with DNA were isolated and characterized by their UV and mass spectra. Tri- and tetrafunctional DNA adducts of 5 were detected. Although the dimers were generally less cytotoxic than MC, dimer 5 was highly and uniformly cytotoxic to all 60 human tumor cell cultures of the NCI screen. Its cytotoxicity to EMT6 tumor cells was enhanced under hypoxic conditions. These findings together verify the expected features of the MC dimers and warrant further study of the biological effects of dimer 5.
Mitomycin C-Dextran conjugates (MMC-D) were intravenously (iv) injected in mice bearing subcutaneous sarcoma 180. The tissue distribution was determined for three 14-C-labeled anionic conjugates (MMC-Dan) with molecular weights of 10, 70, and 500 kd and one cationic 70-kd 14C-conjugate (MMC-Dcat). The anionic conjugates were slowly cleared from the plasma, and their elimination rate decreased with increasing molecular weight. Radioactivity accumulated in liver, spleen, lymph nodes, and tumor but not in heart, lung, intestines, kidney, or muscle after iv injection of all types of 14C-MMC-Dan. In contrast, the cationic conjugate was rapidly cleared from the plasma and accumulated mostly in the liver and spleen, while tumor levels remained low. The antitumor effect of the 70-kd MMC-Dan, which afforded the highest tumor concentration, was superior to that of free MMC. Therefore, anionic mitomycin C-dextran conjugates with a high molecular weight may be useful for tumor targeting in cancer chemotherapy.
Mitomycin, ifosfamide and cis-platin are three of the most active single agents in the chemotherapy of non-small cell lung cancer. We have combined them for a phase 2 study in patients with inoperable non-small cell lung cancer. The regimen ('MIC') comprised: mitomycin 6 mg m-2, ifosfamide 3 g m-2 and cis-platin 50 mg m-2, with routine use of lorazepam, dexamethasone and high dose metoclopramide for anti-emesis. Seventy-four ambulatory patients with untreated, limited (LD) or extensive (ED) disease have entered this study, and 66 are evaluable for response. Thirty patients (45%) have achieved partial remission and 7 (11%) complete remission, as assessed radiologically. The overall response rate is thus 56% (95% confidence interval 44%-68%). There have been 29/43 responses in LD (67%, 95% CI 53%-81%) and 8/23 in ED (35%, 95% CI 15%-55%). The median response duration, measured from the start of treatment is 8.75 months. The median survival for the whole group is 9.2 months. The principal toxicity was nausea and vomiting which was severe or prolonged (greater than 48 h) for one or more courses, in 9% of patients. Performance status (PS) and weight were assessed before, and 3 weeks after the last course of chemotherapy. Fifteen (of 31 evaluable) responders improved their PS and only 1 responder deteriorated. Twenty-one of the 28 evaluable non-responders had no change in PS. The difference in PS change between responders and non-responders is highly significant (P = 0.002). Thirty evaluable responders experienced a mean increase in weight of 2.9% with treatment, whereas 24 evaluable non-responders had a mean weight loss of 3.8%. This change is also highly significant (P = 0.0013). MIC is clearly a well tolerated regime and among the most active combinations in non-small cell lung cancer. It will now be tested in a randomized trial against no chemotherapy.
Two non-transformed human skin fibroblast strains, GM38 and 3437T, were found to be more sensitive to the bioreductive alkylating agents mitomycin C (MMC) and porfiromycin (PM) under hypoxic compared to aerobic conditions. One of these strains, 3437T, was 6-7 times more resistant to these agents under aerobic exposure conditions, but was identical in sensitivity to the normal strain, GM38, under hypoxic conditions. Aerobic 3437T cells demonstrated no increased resistance to cisplatin compared to the normal strain, arguing against enhanced ability to repair DNA interstrand cross-links as the underlying explanation for the mitomycin resistance. The aerobic resistance of 3437T was not altered by dicumarol, an inhibitor of the enzyme DT-diaphorase which is believed to be involved in aerobic activation of MMC and PM. Dicumarol did increase the resistance of GM38, but not to the same level of resistance demonstrated by 3437T. These results suggest that the aerobic MMC and PM resistance of 3437T may arise, in part, from a deficiency in DT-diaphorase activity. The identical sensitivities under hypoxic conditions indicate that drug activation pathways operative in the absence of oxygen are similar in both the normal and 3437T cells.
After instillation of mitomycin C into the urinary bladder severe pulmonary changes developed in a 35-year-old man. This complication has previously been described only after systemic administration of the drug. If mitomycin C is administered locally the lungs should be regularly examined.
Mitomycin C (MC) is a cytotoxic chemotherapeutic agent that causes DNA damage in the form of DNA cross-links as well as a variety of DNA monoadducts and is known to induce p53. The various DNA adducts formed upon treatment of mouse mammary tumor cells with MC as well as 10-decarbamoyl MC (DMC) and 2,7-diaminomitosene (2,7-DAM), the major MC metabolite, have been elucidated. The cytotoxicity of DMC parallels closely that of MC in a number of rodent cell lines tested, whereas 2,7-DAM is relatively noncytotoxic. In this study, we investigate the ability of MC, DMC, and 2,7-DAM to activate p53 at equidose concentrations by treating tissue culture cell lines with the three mitomycins. Whereas MC and DMC induced p53 protein levels and increased the levels of p21 and Gadd45 mRNA, 2,7-DAM did not. Furthermore, MC and DMC, but not 2,7-DAM, were able to induce apoptosis efficiently in ML-1 cells. Therefore the 2,7-DAM monoadducts were unable to activate the p53 pathway. Interestingly, DMC was able to initiate apoptosis via a p53-independent pathway whereas MC was not. This is the first finding that adducts of a multiadduct type DNA-damaging agent are differentially recognized by DNA damage sensor pathways.
The thymidine kinase-deficient subclone, 707BUF, of the Friend murine leukaemia cell line exhibits increased sensitivity to the induction of cytogenetic aberrations by mitomycin C (MMC) relative to wild-type clone 707. It has been suggested that thymidine kinase-deficient cells may be highly mutagen-sensitive through an imbalance of nucleotide pools rendering excision repair error-prone. In this study clone 707 Friend leukaemia cells were compared with subclone 707BUF for sensitivity to the potentiating effect of caffeine on MMC-induced cytogenetic aberrations. The results indicate that although potentiation of mitomycin C-induced cytogenetic damage occurs in both clone 707 and in subclone 707BUF following caffeine treatment, the mutagen-sensitive thymidine kinase-deficient subclone 707BUF had enhanced potentiation by caffeine of MMC-induced cytogenetic damage relative to wild-type clone 707. It is suggested that caffeine may enhance mutagen sensitivity by inhibiting post-replication repair processes and may perhaps also indirectly reduce the effectiveness of the excision repair system by inhibiting the mutagen-induced G2-delay. Clone 707 wild-type cells in the presence of caffeine could then continue to repair DNA damage through an intact though less effective excision repair system, whilst the thymidine kinase-deficient subclone 707BUF would, in the presence of caffeine, be rendered highly mutagen sensitive, being only able to repair DNA damage through an error-prone excision repair process.
Thirteen courses of high-dose mitomycin-C with autologous bone marrow transplantation (ABMT) were administered to 12 patients. Four dose schedules were evaluated: A) 60 mg/M2 X 1, 60-min infusion; B) 30 mg/M2/day X 2, 15-min infusion; C) 30 mg/M2/day X 2, 60-min infusion; D) 15 mg/M2/day X 4, 60-min infusion. Pharmacokinetic studies using HPLC technique were done in nine patients. All patients have since died and autopsies were performed in nine patients. Two major nonhematopoietic toxicities were encountered and were dose-schedule dependent: hemorrhagic colitis (six of six courses in Schedules A and B; two of seven in Schedules C and D), and hepatic dysfunction (five of six in Schedules A and B; two of seven in Schedules C and D). Histopathologic evidence of venocclusive disease of the liver was present in four of five autopsies in Schedules A and B, and two of four in Schedules C and D. One patient died as a result of liver failure associated with submassive hepatic necrosis. Saturation kinetics described by other investigators cannot be confirmed by our pharmacokinetic analyses in nine patients. Severe nonhematopoietic toxicities of mitomycin-C were found at three times the conventional dose; thus, this drug is assessed as not being clinically useful as a single agent in ABMT.
Fifty-five patients with metastatic carcinomas of unknown primary site (50 adenocarcinomas) were randomized, after stratification, to treatment with either mitomycin and doxorubicin (MA) or mitomycin, doxorubicin, and cisplatin (MAP). There was a moderate but nonsignificant improvement in regression frequency (14 vs. 27%) and a slight but also nonsignificant worsening of survival (median 5.5 months vs. median 4.6 months) by the addition of cisplatin at 60 mg/m2 to the MA regimen.
Fifteen consenting patients with brain metastases recurrent after cranial irradiation were treated with intraarterial mitomycin-C, 15 mg/m2, administered in a total final volume of 100 ml 0.45% saline over 20 min through a transfemoral catheter with a 0.2-mu in-line filter. There were 2 early deaths (one probably drug-related). Of the 13 evaluable patients, 6 (46%) responded, with both computed tomography (CT) scan and neurological improvement. Median response duration was 25 weeks, and median survival of all 15 patients was 17 weeks. Neurological, ocular, and local skin toxicity were dose-limiting. The degree of toxicity was comparable to that we have noted with other intracarotid regimens, and it appears to be less toxic when infused into the vertebral artery than are most other drugs (although experience is still limited and caution still needs to be exercised). We do not recommend that this replace or be added to cranial irradiation as front-line treatment of brain metastases, but we feel that it is an effective and reasonably well-tolerated regimen for treatment of brain metastases that have recurred after cranial irradiation. We are currently initiating studies of intraarterial mitomycin-C combined with intraarterial cisplatin and teniposide (VM-26) as treatment for recurrent brain metastases.
Nineteen patients with poor prognosis squamous cell cancer of the cervix were treated with concurrent radiation therapy (RT) and chemotherapy between February 1986 and July 1988. Treatment consisted of intravenous Mitomycin C 10 mg/m2 on days 1 and 43 and cis-platinum 50 mg/m2 on days 1, 22, and 43. All patients received external RT (5,000 cGy in 28 fractions) and brachytherapy (6,000 cGy to point A.) Additionally, patients with paraaortic lymph node involvement received 4,000 cGy paraaortic RT. The toxicity of this regimen was assessed using Southwest Oncology Group criteria. Toxicity was acceptable and did not significantly delay RT. In addition, complete pelvic response was noted in 18 of 19 (95%) patients within month of completion of therapy and maintained despite distant metastases. At the time of this report, 14 of the 19 patients are alive 9-22 months after initiation of treatment. Chemotherapy with cis-platinum and Mitomycin C concurrently with RT is feasible in patients with locally advanced cervical cancer. Further follow-up of our patients is required to determine whether this regimen will have a favorable impact on survival.
As a result of their previous experience with mitomycin C at high discontinuous doses in advanced gastric cancer, the authors studied its role as an adjuvant for locally advanced cases after surgical complete resection. Results from 70 evaluable patients are presented. Patients were allocated randomly to receive mitomycin C, 20 mg/m2 I.V. direct once every 6 weeks, four courses, or a placebo. After a follow-up period of 250 weeks, seven patients of treatment arm and 23 controls have already relapsed (p less than 0.001). Toxicity was moderate and controllable by symptomatic measures. The authors consider this investigation a positive contribution in the field of adjuvant therapy of gastric cancer.
In this study the activity of KW-2149 and two of its metabolites, M-16 and M-18, was measured against cell lines with different types of resistance. The influence of these metabolites and of the exposure time on the cytotoxic efficacy of KW-2149 was investigated. Against the human ovarian carcinoma cell lines, AOvC and A2780, KW-2149 was more active than mitomycin C (MMC), with an IC50 of, respectively, 3.4 nM and 9.82 microM for KW-2149 and 18.2 nM and 67.71 microM for MMC. Activity of M-18 was significant against both cell lines and was comparable with that of KW-2149. Against an MMC-resistant cell line, AOvCMMC, the resistance factor (RF) for KW-2149 was 3.1 versus 8.0 for MMC. Tested against a cisplatin-resistant cell line, AOvCCDDP, KW-2149 had a RF of 7.7 versus 2.4 for MMC. Increasing the exposure time from 1 to 8 h decreased the RF for KW-2149 from 7.7 to 3.0. In an MDR mediated resistant cell line, A2780mdr+, prolongation of exposure time increased RF for KW-2149 and MMC but decreased RF for M-18 from 7.0 at 1 h to 5.3 at 8 h. Tested against a rat colon carcinoma cell line CC531, KW-2149 and M-18 again demonstrated superior or equal activity compared with MMC, IC50 being, respectively, 0.6, 2.1 and 2.6. Here again M-18 showed an aberrant sensitivity pattern, as its activity decreased with mdr-1 expression in contrast to the other mitomycins. Our data confirm the activity of KW-2149 as an agent with equal or superior activity as compared with MMC. It is concluded that the metabolite M-18 can contribute to the activity of KW-2149. Efficacy of both KW-2149 and its metabolites increases with increasing exposure times. The increments of exposure time appeared even as a means to overcome resistance in some instances.
A virulent bacteriophage was isolated from lysates of Bacillus stearothermophilus strain NU-10 induced either by treatment with mitomycin C or by shifts in temperature. Optimum conditions for induction, morphology and other properties of the virus are described. Chloroform treatment and shifts in temperature of producer cells released approximately similar amounts of phage as did mitomycin induction, suggesting an effect on release rather than on synthesis of the virus.