Induction and chemotherapeutic response of two transplantable ductal adenocarcinomas of the pancreas in C57BL/6 mice.

Following implant of cotton thread-carrying 3-methyl-cholanthrene into the pancreas tissue of 90 C57BL/6 and 60 BALB/c mice, 13 developed ductal adenocarcinomas. Two of these tumors, both of C57BL/6 origin (Panc 02 and 03), were established in serial s.c. transplant. Panc 02 was treated with 37 different anticancer drugs representing all of the chemical and functional classes of clinically useful anticancer agents including alkylating agents, antimetabolites, agents that bind to or cause scission of DNA, and others that inhibit mitosis or inhibit protein synthesis. When drug treatment was started within 3 to 4 days after tumor implant, Panc 02 showed only limited response to treatment with two nitrosoureas, [N'-[(4-amino-2-methyl-5-pyrimidinyl)methyl]-N-(2-chloroethyl)-N- nitrosourea, monohydrochloride and N-(2-chloroethyl)-N'-(2,6-dioxo-3-piperdinyl)-N-nitrosourea)], and N-phosphonacetyl-L-aspartate. Drug response of Panc 03 was determined only with Adriamycin, 5-fluorouracil, cyclophosphamide, cis-(SP-4-2)-diamminedichloroplatinum, or N,N'-bis(2-chloroethyl)-N-nitrosourea. When drug treatment was started 3 days after tumor implant, high cure rates were obtained with Adriamycin treatment, and limited therapeutic responses were seen to treatment with cis-diamminedichloroplatinum or cyclophosphamide. A comparison of the biological characteristics and drug responsiveness of Panc 02 and Panc 03 with those of a number of other transplantable tumors of mice is reported.

Tumor stem cell heterogeneity: implications with respect to classification of cancers by chemotherapeutic effect.

Herein we have considered the types of tumor stem cell heterogeneity that might account for (a) fluctuating degrees of response to chemotherapy in similarly treated individuals bearing a particular neoplasm, and (b) classifications of cancers by chemotherapeutic effect. Fluctuating ratios of T/R to T/O stem cells, as predicted by the mutation theory, will account for (a). In different circumstances at least three phenomena might account for (b): growth fraction differences, differences in T/R to T/O stem cell ratios, or differences with respect to pharmacologic sanctuaries. T/R stem cells are primarily responsible for the failure of the best available chemotherapy to cure responsive, refractory, and very refractory experimental neoplasms. The data examined suggest that differences in the T/R to T/O stem cell ratios in different types of cancer may account for their being classed as responsive, refractory, or very refractory. If this be true, what might underlie such differences? The most obvious possibilities are: higher mutation rates to a drug-resistant state in refractory cancers, or some sort of "natural selection" of diverse T/R stem cells in refractory cancers.

Establishment of cross-resistance profiles for new agents.

Sublines of murine leukemias (L1210 and P388) and solid tumors selected for resistance to representatives of all of the chemical and functional classes of clinically useful anticancer drugs have been isolated and established in serial in vivo passage and, in some cases, in vitro culture. Extensive resistance, cross-resistance, and collateral-sensitivity patterns have been established with most of the sublines of the drug-resistant murine leukemias under treatment with greater than 100 different established and clinically useful anticancer drugs or new candidate anticancer drugs currently under study. Patients selected for inclusion in phase I-II trials usually have tumors that have failed to respond to treatment with established clinically useful drugs, either from the start of treatment or during continuing treatment after initial useful response. These treatment failures are no doubt due, in many cases, to drug-resistant tumors if initially unresponsive or to the overgrowth of drug-resistant mutant tumor stem cells in initially responding patients who ultimately failed under continuing treatment. Therefore, the cross-resistance profiles of drug-resistant murine tumors to treatment with new drugs going into phase I-II trials should provide useful guides for patient selection for those trials. Also, these cross-resistance profiles will provide useful information indicating likely biochemical mechanism of action of new drugs with promising anticancer activity, thus guiding drug selection for combination chemotherapy trials in animals or man. Numerous examples of all of the above indications for useful application of such information derived from chemotherapy trials with drug-resistant murine tumors are reported.

Response of transplantable tumors of mice to anthracenedione derivatives alone and in combination with clinically useful agents.

Other investigators have demonstrated that dihydroxyanthracenedione (DiOHA) and anthracenedione acetate (AA) are active against a broad spectrum of transplantable mouse tumors. DiOHA and AA are in clinical trial in the US; AA is in clinical trial in Europe. Because of the broad spectrum of activity of these DNA binders against murine tumors and due to their promising clinical utility, we have evaluated these agents in combination with a variety of clinically useful antitumor drugs. Studies were carried out against three colon adenocarcinomas (38, 06/A, and 11/A), three mammary adenocarcinomas (13/C, 16/C, and 14), and two lymphocytic leukemias (P388 and L1210). The therapeutic synergism of one of these combinations, DiOHA and cisplatin, has been previously reported. Four additional combinations which were found to have confirmed therapeutic synergism are reported here: DiOHA and palmO-ara-C, DiOHA or AA and 5-FU, DiOHA or AA and vincristine, and DiOHA and decarbazine. The combination toxicity indices (CTI; a measure of the degree of overlap in dose-limiting toxic effects) were obtained for all the following combinations: DiOHA and palmO-ara-C = 1.25-1.6; DiOHA or AA and 5-FU = 1.2-1.3; DiOHA or AA and vincristine = 1.6; and DiOHA and dacarbazine = 1.3-1.5. A CTI of 1.0 indicates complete overlap in dose-limiting toxic effects, eg, only 50% of the maximum tolerated dose of each agent can be used in combination. On the other hand, a CTI of 2.0 indicates no overlap in toxicity, and 100% of the maximum tolerated dose of each agent can be used in combination.

Toxicity and anticancer activity of a new triazine antifolate (NSC 127755).

A new triazine folate antagonist, 3-chloro-4-((4-(2-chloro-4-[4,6-diamino-2,2-dimethyl-s-triazin-1(2H)-yl]phenyl)butyl)) benzenesulfonyl fluoride compounded with ethanesulfonic acid (1:1) (NSC 127755), was highly active against four transplantable colon adenocarcinomas (36, 38, 10/A, 12/A) and the Dunning murine ovarian tumor M5076. Treatment schedule studies indicated that a prolonged time of exposure provided optimum antitumor activity for the compound. The combination of NSC 127755 plus 4-amino-1-[5-O-(1-oxohexadecyl)-beta-D-arabinofuranosyl]-2(1H)-pyrimidinone (palmO-ara-C, NSC 135962) was found to have therapeutic synergism against grossly evident colon adenocarcinoma 36.

Synergistic antileukemic activity of combinations of two nitrosoureas.

A rationale based on known chemical, biochemical, and biologic properties of nitrosoureas led to the testing of combinations of CCNU with chlorozotocin for in vivo activity against L1210 leukemia. Several combinations yielded synergistic antileukemic activity.

Clinical concepts derived from animal chemotherapy studies.

Animal chemotherapy studies have contributed significantly to clinical concepts in tumor therapy. Preclinical investigations have led to the discovery of new drugs and have demonstrated that it is possible to cure advanced metastatic neoplasia. A fundamental clinical concept stemming from animal chemotherapy studies is that increased selectivity and improved therapeutic effectiveness of antitumor agents may result from appropriate pharmacologic, biochemical, and biologic manipulation of the host-tumor drug relationship. Clinically important factors that may increase antitumor drug selectivity are reviewed and pertinent studies in animal model systems are cited.

Absence of delayed lethality in mice treated with aclacinomycin A.

Two compounds that bind to or intercalate with DNA (DNA binders), e.g., adriamycin and 'dihydroxyanthracenedione', 9,10-anthracenedione, 1,4-dihydroxy-5,8-bis[[2-[(2-hydroxyethyl)-amino]ethyl]amino]-, dihydrochloride salt, consistently caused delayed lethality (20-200 days after treatment) if administered intraperitoneally (IP). Both of these agents contain para-hydroxyl groups in the ring adjacent to the quinone ring. Certain analogs of these compounds (aclacinomycin A and 'anthracenedione acetate', 9,10-anthracenedione, 1,4-bis[[2-[(2-hydroxyethyl)amino]ethyl]amino]-, diacetate (salt), which do not contain para-hydroxyl groups, did not cause delayed deaths when injected IP. The only difference in the molecular structure (other than the nature of their amine salts) between dihydroxyanthracenedione and anthracenedione acetate lies in the para-hydroxyl groups in the ring adjacent to the quinone ring. Another compound that binds to DNA, m-AMSA, which has neither the quinone function nor the para-hydroxyl groups, did not cause delayed deaths after IP administration.

Metabolism and chemotherapeutic activity of 9-beta-D-arabinofuranosyl-2-fluoroadenine against murine leukemia L1210 and evidence for its phosphorylation by deoxycytidine kinase.

The 2-fluoro derivative of 9-beta-D-arabinofuranosyladenine (2-F-ara-A) and its soluble 5'-formate and 5'-phosphate derivatives were therapeutically effective against the parent leukemia L1210 (L1210/0). 2-F-ara-A and 9-beta-D-arabinofuranosyladenine 5'-formate were inactive aginst a 1-beta-D-arabinofuranosylcytosine-resistant subline (L1210/ara-C) that was deficient in deoxycytidine kinase. Deoxycytidine prevented 2-F-ara-A-induced inhibition of proliferation of L1210/0 cells in culture and alleviated 2-F-ara-a inhibition of DNA synthesis. After treatment of mice with 9-beta-D-arabinofuranosyladenine 5'-formate, intracellular levels of the 5'-triphosphate of 9-beta-D-arabinofuranosylfluoroadenine in leukemia cells were more than 10 times higher in L1210/0 cells than in L1210/ara-C cells. Similar results were obtained in this line of leukemia cells from mice treated with the 5'-monophosphate of 9-beta-D-arabinofuranosyl-2-fluoroadenine. Thus, L1210/ara-C cells deficient in deoxycytidine kinase activity were also deficient in capacity to phosphorylate 2-F-ara-A. Kinase activity from L1210/0 cells for deoxycytidine and for 2-F-ara-A coeluted from calcium phosphate cellulose and from diethylaminoethyl cellulose columns and had similar mobility on gel electrophoresis. Deoxyadenosine kinase was clearly separated from deoxycytidine kinase. Deoxycytidine competed with 2-F-ara-A for phosphorylation by the partially purified enzyme from L1210 cells. These results indicate that 2-F-ara-A is phosphorylated to the 5'-monophosphate by deoxycytidine kinase of leukemia L1210 cells.

Erythro-9-(2-hydroxy-3-nonyl) Adenine alone and in combination with 9-beta-D-arabinofuranosyladenine in treatment of systemic herpesvirus infections in mice.

Although the antiviral activity of erythro-9-(2-hydroxy-3-nonyl)adenine, a potent adenosine deaminase inhibitor, against herpes simplex virus type 1 in cell culture was readily confirmed, the compound was found to be totally ineffective in the treatment of experimentally induced systemic herpes simplex virus type 1 infections in Swiss mice. Data were obtained, however, which clearly indicated that the antiviral potency of 9-beta-D-arabinofuranosyladenine in vivo could be enhanced by the co-administration of low, nontoxic doses of erythro-9-(2-hydroxy-3-nonyl)adenine.