Cell survival in four ovarian carcinoma xenografts following in vitro exposure to melphalan, cisplatin and cis-diammine-1,1-cyclobutane dicarboxylate platinum II (CBDCA,JM8)

Characterization of human ovarian carcinomas in a SCID mouse model

This study characterizes a murine model which is promising for the study of the growth and natural history of ovarian cancer and for testing of new therapies for its treatment. Intact portions of 20 different human ovarian cancer surgical specimens were implanted in over 60 severe combined immunodeficient (SCID) mice using techniques previously developed in our laboratory. Growth of xenografts was evaluated by gross examination and histopathologic analysis. Confirmation of the human origin of the tumor outgrowth was obtained using in situ hybridization analysis. By histological evaluation, all of the patients' tumors showed evidence of invasive growth in at least 1 of the mice implanted with portions of each surgical specimen and these tumors remained morphologically similar to the parent tumors for a long period of time. Furthermore, 65% (13/20) of the xenografts grew rapidly enough (i.e., reached a diameter of 1-2 cm within 2-6 months) to allow passage to subsequent SCID mice. Among the passaged xenografts, 3 eventually developed metastases in a distribution pattern similar to that of naturally occurring ovarian cancer and 2 developed ascites without evidence of further metastatic spread. Upon evaluation of sera from tumor-bearing mice, human antibodies presumably derived from immunoglobulin-secreting cells present in the original tumor specimen were identified. In support of this, human B cells and plasma cells could be seen within the tumor xenograft for more than 6 months following implantation. In summary, transplantation of surgical specimens from ovarian cancer patients into SCID mice results in an attractive model for the study of the natural history of ovarian cancer and may also be useful for analysis or new experimental therapeutic approaches for the treatment of this disease.

Dose escalation study of carboplatin with fixed-dose etoposide plus granulocyte-colony stimulating factor in patients with small cell lung carcinoma. A study of the Lung Cancer Study Group of West Japan

BACKGROUND

We performed a Phase I-II trial to determine the maximum tolerated dose of carboplatin (CBDCA) with a fixed dose of VP-16 and granulocyte-colony stimulating factor (G-CSF) in small cell lung cancer (SCLC) patients.

METHODS

Treatment consisted of a starting dose of CBDCA, 400 mg/m2 (i.v., Day 1); VP-16, 100 mg/m2 (i.v., Days 1-3), and G-CSF, 2 micrograms/kg (s.c., Days 4-17) every 4 weeks for four cycles. The dose of CBDCA was escalated in increments of 50 mg/m2 until Grade IV toxicity on the World Health Organization scale developed in two-thirds or more of the patients.

RESULTS

Seventy-five previously untreated patients with pathology confirmed SCLC were entered into the trial. Seventy-one patients were eligible and 70 patients were evaluated for response. Forty-five patients had limited disease (LD) and 26 had extensive disease (ED). The response rate of the 70 patients who could be evaluated was 81%, with 23% attaining a complete response (CR) and 58% attaining a partial response (PR). The response rate was 80% in LD patients (CR, 23%; PR, 57%) and 85% in ED patients (CR, 23%; PR, 62%). The major dose-limiting toxicity was thrombocytopenia. Nephrotoxicity, neurotoxicity, and ototoxicity were uncommon. The doses of CBDCA that resulted in unacceptable thrombocytopenia were 700 mg/m2 in patients younger than 70 years and 500 mg/m2 in patients older than 70 years. Overall median survival time (MST) was 9 months. MST of LD patients and ED patients were 11 months and 7 months, respectively. The dose-limiting toxicity of CBDCA with a fixed dose of VP-16 and using G-CSF as bone marrow rescue was age-related thrombocytopenia. The maximum tolerated dose of CBDCA was 650 mg/m2 if patients were younger than 70 years and 450 mg/m2 if they were 70 years or older.

CONCLUSIONS

When we retrospectively compared our results with those using standard chemotherapy regimens, we saw no therapeutic benefit from increasing planned doses of CBDCA up to 700 mg/m2 in combination with G-CSF in patients with SCLC.

Cisplatin-carboplatin therapy in extensive non-small cell lung cancer: a Cancer and Leukemia Group B study

The response to cisplatin in non-small cell lung cancer (NSCLC) is limited by the renal and neurological toxicities of this agent. Carboplatin has modest activity in NSCLC and when given in conventional doses has a different spectrum of toxicity. Both drugs were administered to 76 eligible patients with advanced NSCLC. No patient had been previously treated with chemotherapy. Cisplatin 50 mg/m2 and carboplatin 350 mg/m2 were administered every 28 days until disease progression occurred. There was 1 complete response and the overall response rate among the 68 evaluable for response patients was 13%. Neither histological subtype nor initial performance status was a significant factor influencing response. Median survival was 5.1 months with significant differences based on initial performance status but not on histological subtype. Severe or life-threatening leukopenia and thrombocytopenia occurred in 23% and 36% of the 76 patients, respectively. There were 2 toxic deaths, 1 each due to infection and haemorrhage. The efficacy of this combination is not different from that of carboplatin alone, and the combination may be of greater benefit in patients with more responsive tumours than NSCLC.

The establishment, characterization and calibration of human ovarian carcinoma xenografts for the evaluation of novel platinum anticancer drugs

Twenty-three serially transplantable ovarian carcinoma xenografts have been established in female nude mice from forty-two donor samples provided by both previously treated and untreated patients. The lines are all of human karyotype and mirror the histopathology of the original explant. Sixteen examples have been calibrated against four reference platinum drugs: cisplatin, carboplatin, iproplatin, tetraplatin. Three distinct patterns of response were observed: (i) tumours which were comparably sensitive to all four drugs (2 lines); (ii) tumours which were comparably refractory to treatment with all four drugs (5 lines); (iii) tumours which exhibited "individual" patterns of response to the group of calibrating drugs (9 lines). The "response rate" overall of the tumour panel to each of the clinically used drugs was 44% (7/16), though the pattern of response was not identical for each drug. Only 2/16 tumours (13%) were sensitive to tetraplatin, these also being the same tumours which were particularly sensitive to the other three drugs. It was also possible to confirm in 8/9 lines that the therapeutic response of the xenograft reflected that of the corresponding patient's tumour to platinum-based chemotherapy. This tumour panel has now been adopted for evaluating novel platinum-based drugs designed specifically for the treatment of ovarian cancer.

Carboplatin. A preliminary review of its pharmacodynamic and pharmacokinetic properties and therapeutic efficacy in the treatment of cancer

Carboplatin is a 'second-generation' platinum compound advocated for use in the treatment of patients with ovarian cancer and it has also shown promise in small cell lung cancer, squamous cell carcinomas of the head and neck, and seminomas. Overall, it would appear to have a similar qualitative spectrum of activity to cisplatin. There have been few comparative trials with carboplatin, either alone or in combination with other chemotherapeutic agents, but the limited data suggest comparable efficacy with cisplatin in ovarian cancer. Importantly, the toxicity profile of carboplatin is markedly different from that of cisplatin, with nephrotoxicity, neurotoxicity and ototoxicity occurring only infrequently with carboplatin. As with cisplatin, nausea and vomiting occur in many patients after carboplatin administration, but symptoms are usually delayed for several hours and are mild to moderate in severity - dose-limiting nausea and vomiting are infrequent with carboplatin. The dose-limiting toxicity of carboplatin is myelosuppression, with severe thrombocytopenia and less often leucopenia, which may be more severe in older patients or in those with renal impairment or those who have had previous chemotherapy. Thus, preliminary data suggest that carboplatin is a therapeutically equivalent alternative to cisplatin, but with a differing toxicity profile that should offer advantages over cisplatin in many patients.

Evaluation of mouse lip mucosa reactions after combinations of cis-diammine-1,1-cyclobutanedicarboxylate platinum (II) (CBDCA) and irradiation: single and fractionated treatments

The influence of CBDCA (JM8) on the radiation-induced mouse lip mucosal reactions has been tested. Both single and fractionated drug doses were used intraperitoneally at 60 mg/kg and 5 X 25 mg/kg respectively. A single injection of CBDCA did not alter the response to a single radiation dose, whether the drug was given at different time intervals from 24 hr prior, to 96 hr after irradiation. A concomitant treatment of daily CBDCA injections and irradiations for 5 consecutive days demonstrated no change of the capacity to repair sublethal radiation damage. When two equal sized radiation doses were separated by 10 days and CBDCA was administered daily from day 3 to 7, the ability to repopulate the lip mucosa epithelium during the radiation-free period was not influenced.

Radiosensitization in vitro by cis-diammine (1,1-cyclobutanedicarboxylato) platinum(II) (carboplatin, JM8) and ethylenediammine-malonatoplatinum(II) (JM40)

The radiosensitizing ability of two analogues of cisplatin have been tested in vitro. The analogues, CBDCA (JM8) and EDMP (JM40), are currently undergoing clinical tests in the search for an active but less toxic cancer chemotherapeutic agent than cisplatin. The compounds were cytotoxic to log phase RIF1 cells in culture, but at higher concentrations than the parent compound. Both analogues were radiosensitizers of oxic cells when given as 1 h exposures beginning either 3 h before, 1 h before or 2 h after irradiation, giving modest enhancements of approximately 1.2. Each drug caused an inhibition of the repair of sublethal damage which was greatest after CBDCA treatment. Although neither analogue was as good a radiosensitizer as cisplatin, CBDCA appears to show promise as a potential radioenhancing platinum compound.

Radiosensitization by cisplatin of RIF1 tumour cells in vitro

The ability of cis-diamminedichloroplatinum (II) (c-DDP) to enhance radiation-induced cell killing was tested on oxic RIF1 tumour cells in monolayer culture. Marked radiosensitization of the survivors of a 1 h drug treatment was found with all c-DDP doses tested, with enhancement ratios increasing from 1.2 to 2.2 with increasing drug dose. Isobologram analyses showed that the interactions of c-DDP with X-rays were supra-additive. To test whether part of the enhancement was due to a selection of subpopulations, the diploid and tetraploid RIF1 cells, which normally coexist in culture, were separated by unit gravity velocity sedimentation, and by developing diploid and tetraploid clones. Both methods showed that there was little difference in either drug sensitivity or radiation sensitivity between diploid and tetraploid cells. DNA histograms obtained by flow cytometry showed little or no cycle progression during the 1 h drug treatment. These data indicate that the radiosensitization was not the result of the drug exposure leaving cells in a radiosensitive phase. The observed radiosensitization, therefore, appears to have resulted from a true drug/X-ray interaction.