Milan Potmesil

Neoadjuvant chemotherapy with CPT-11 and cisplatin downstages locally advanced gastric cancer

We examined the role of neoadjuvant therapy in downstaging locally advanced gastric cancer. Preoperative staging was performed with a combination of CT scans, endoscopic ultrasonography and/or laparoscopy, and laparoscopic ultrasonography. Patients with T ⋝3 tumors and/or node-positive disease by preoperative clinical staging were eligible for entry. Neoadjuvant therapy consisted of two cycles of CPT-11 (75 mg/m2) with cisplatin (25 mg/m2) weekly four times every 6 weeks. This was followed by resection with D2 lymph node dissection and two cycles of intraperitoneal chemotherapy with floxuridine and cisplatin. Twenty-two patients were entered into the study (4 with T3N0 disease and 18 with T3N1 disease). Induction chemotherapy was well tolerated with major toxicities being neutropenia and diarrhea. A median of 78%/75% of the planned dosage of CPT-11/cisplatin was delivered. Two patients withdrew consent during the first cycle and were lost to follow-up. One patient progressed to stage IV disease during induction chemotherapy and did not undergo surgery. Nineteen patients underwent surgery. One patient had undetected stage IV disease (liver) and underwent a palliative R2 resection. Of the 18 remaining patients, 17 had curative R0 resections and one had a palliative R1 resection. A median of 21 lymph nodes (range 1 to 121) were examined histologically. There was one postoperative death. Surgical morbidity did not appear to increase after the neoadjuvant regimen. The median postoperative length of hospital stay was 9 days (range 3 to 75 days). Postoperative pathologic staging yielded 16% T3 lesions compared to 85% before treatment based on clinical staging; postoperative American Joint Committee on Cancer staging yielded 37% stage IIIA disease compared to 70% stage IIIA before treatment. With a median follow-up of 15 months, median survival has not yet been reached. We conclude that CPT-11-based neoadjuvant therapy downstages locally advanced gastric cancer. Further follow-up is necessary to determine the ultimate impact of this combination therapy on recurrence and survival.

Complications of gastrectomy following CPT-11-based neoadjuvant chemotherapy for gastric cancer

Potential benefits of neoadjuvant therapy for locally advanced gastric cancer include tumor downstaging and an increased R0 resection rate. Potential disadvantages include increased surgical complications. This study assesses postoperative morbidity and mortality by comparing patients undergoing gastrectomy with and without neoadjuvant chemotherapy. From October 1998 to July 2002, a total of 34 patients with locally advanced gastric cancer were placed on a phase II neoadjuvant chemotherapy protocol consisting of two cycles of CPT-11 (75 mg/m2) with cisplatin (25 mg/m2). Demographic, clinical, morbidity, and mortality data were compared for these patients (CHEMO) versus 85 patients undergoing gastrectomy without neoadjuvant chemotherapy (SURG). The CHEMO patients were more likely to be less than 70 years of age (P ≦ 0.01), have proximal tumors (P ≦ 0.01), and undergo proximal gastrectomy (P ≦ 0.025). Fifty-two percent of SURG patients had T3/T4 tumors compared to 19% of CHEMO patients, consistent with tumor downstaging. The R0 resection rate was similar (80%). Morbidity was 41% in CHEMO patients and 39% in SURG patients. There were five postoperative deaths (4.4%), two in the CHEMO group and three in the SURG group (P = NS). It was concluded that neoadjuvant chemotherapy with CPT-11 and cisplatin is not associated with increased postoperative morbidity compared to surgery alone. CPT-11-based neoadjuvant chemotherapy should be tested further in combined-modality treatment of gastric cancer.

Cell kinetics of irradiated experimental tumors: cell transition from the non-proliferating to the proliferating pool.

Parenchymal tumor cells of murine mammary carcinomas can be divided into two pools, using nucleoli as morphological ‘markers’. Cells with dense nucleoli traverse the cell cycle and divide, thus constituting the proliferating pool. Cells with trabeculate or ring‐shaped nucleoli either proceed slowly through G1 phase or are arrested in it. The role of these non‐proliferating, G1 phase‐confined cells in tumor regeneration was studied in vivo after a subcurative dose of X‐irradiation in two transplantable tumor lines. Tumor‐bearing mice were continuously injected with methyl[3H]thymidine before and after irradiation. Finally, the labeling was discontinued, mice injected with vincristine sulfate and cells arrested in metaphase were accumulated over a 10‐hr period. Two clearly delineated groups of vincristinearrested mitoses emerged in autoradiograms prepared from tumor tissue at the time of starting tumor regrowth: one group with the silver‐grain counts corresponding to the background level, the other with heavily labeled mitoses. As the only source of unlabeled mitoses was unlabeled G1 phase‐confined cells persisting in the tumor, this observation indicated cell transition from the non‐proliferating to the proliferating pool, which took place in the initial phase of the tumor regrowth. Unlabeled progenitors have apparently remained in G1 phase for at least 5–12 days after irradiation.

Preclinical and clinical development of camptothecins.

Publisher Summary The camptotheca tree (Camptotheca acuminata, Decaisne, Nyssaceae) powder—an injectable, or an effusion, prepared from the bark, roots, and fruit—has been used to treat patients with gastrointestinal and other types of cancer. The extract of camptotheca was tested by the National Cancer Institute and the antitumor activity was established in experimental systems. It was found that camptothecin (CAM), the naturally occurring lactone form of the alkaloid, inhibited both DNA and RNA syntheses, the former irreversibly, and caused DNA fragmentation in cultured mammalian cells. The CAM lactone form showed activity against rodent L12 10 leukemia and Walker 256 carcinosarcoma. CAM was effective in the xenograft model system than any of the clinically available anticancer drugs used as controls. CAM has been shown to have significant activity in a central nervous system metastatic model using xenograft lines of malignant melanoma and lung adenocarcinoma Several CAM analogs induced accumulation of cleavable complexes in tissue culture cells, inhibited topo1 in cell-free screens, and also showed antitumor activity in vivo . 9-AC was effective in both small and bulky tumors. Given via the gastrointestinal tract, 9-AC is fully active and induces, at somewhat higher doses, complete remissions of human cancer xenografts. CPT-11 (7-ethyl-10-[4-(1-piperidyl)-1-piperidyl] carbonyloxy-camptothecin] is a prodrug with only limited cytotoxic activity, which is converted in biological systems into an active metabolite, SN-38, by the action of carboxylesterases. The best activity of CPT-11 was recorded in the treatment of the xenografts of childhood rhabdomyosarcoma. CPT-11 was also active against human cancer xenografts resistant to topotecan, vincristine, or melphalan. Topotecan had antitumor activity in vitro as well in in vivo screens. This chapter discusses the pharmacokinetics and toxicity of CAM, combination therapy and drug resistance. Current tests of combination treatments with anticancer drugs, growth factors, cytokines will contribute to defining the role camptothecins in standard treatment protocols.

CELL KINETICS OF IRRADIATED EXPERIMENTAL TUMORS: RELATIONSHIP BETWEEN THE PROLIFERATING AND THE NONPROLIFERATING POOL

The role of nonproliferating cells in tumor regeneration has been studied after subcurative doses of low L.E.T. irradiation. Radiation was applied in a single dose at three different levels, 0–47, 0–94 and 1–88 krad. Studies included estimation of the absolute number of cells per tumor, differential cell counts, and autoradiographic determination of kinetic variables, employing transplantable mouse mammary adenocarcinoma DBAH.

Studies on drug resistance in chronic lymphocytic leukemia

Chronic lymphocytic leukemia is a neoplastic disease in which drug resistance invariably occurs. We have studied the uptake and interaction with molecular targets of two drugs, chlorambucil and adriamycin, in CLL lymphocytes and CHO cell lines. Resistance does not appear related to uptake for either drug. Exposure to CLB causes DNA cross-links in the sensitive but not in the resistant cell line. The GSH content of B-CLL lymphocytes is depleted after a 20-hr incubation. An inability to maintain its GSH content may contribute to this cells vulnerability to CLB. The resistance of CLL lymphocytes to ADR may be related to the undetectable levels of its target enzyme DNA topoisomerase II. Future approaches may involve study of novel anthracyclines, DNA topoisomerase I inhibitors and the development of in vitro predictive tests.

In vivo effects of adriamycin or N-trifluoroacetyladriamycin-14-valerate on a mouse lymphoma

Abstract The antitumor activity of adriamycin (ADR) and its analog N -trifluoroacetyladriamycin-14-valerate (AD32) was studied in vivo in a solid form of the transplantable mouse B cell lymphoma DBA3. At the selected single dose of 15 mg/kg of ADR, and 80 mg/kg of AD32, both drugs had comparable effects in overall tumor control. These two dosages were used throughout the experiments, which were designed to elucidate some of the antitumor mechanisms of action of the tested compounds. The recovery kinetics of clonogens were studied using the agar diffusion chamber technique. In ADR-treated tumors, maximal reduction of the survival fraction of colony-forming cells (DC-cfu) was observed at 18 hr post-injection. Over the next 6 hr the number of DC-cfu increased 3.9-fold and returned to pre-treatment levels. Since cell division or cell loss, measured with flow cytometry or with the [ 125 I ]-iododeoxyuridine assay respectively, cannot explain rebound of clonogens in treated tumors, the changes of DC-cfu strongly suggests the presence of a repair of ADR-induced damage in cells left in situ over a 24-hr period. This event was shown at time-intervals when significant levels of ADR were still detectable by HPLC in tumor tissues. The appearance and disappearance of ADR-induced DNA-protein crosslinks and protein-associated DNA single-strand breaks, established by the DNA alkaline elution technique, coincided temporally with the rebound of DC-cfu, suggesting repair of ADR damage at the molecular level. In AD32-treated tumors, maximal decrease of the survival fraction of DC-cfu was present at 12 hr post-treatment. There was only a gradual return to pre-treatment levels over the next 1.5 days . While the rebound of DC-cfu cannot be explained by selective cell loss, flow-cytometric data showed a synchronous cell cohort passing through the cell-cycle phases at 12–48 hr post-treatment, contributing to cell replication. DNA alterations induced by AD32 were identical with those caused by ADR. In partial contrast to the findings with ADR, their removal could indicate replacement of damaged cells by newly generated undamaged cells and/or ‘repair’ of DNA. In conclusion, the results suggest that AD32 has several potential therapeutic advantages over its parent compound: (1) AD32 did not induce an efficient and clearly discernible repair of tumor cells, whereas a repair mechanism, responding to a high toxic dose of ADR, could be present in ADR-treated tumors; (2) the decrease in the number of DC-cfu in tumors treated with AD32 lasted over 2 days , as compared to only 12 hr in ADR-treated tumors; (3) synchronization of a cell cohort, which might be utilized in drug combination treatments, was induced by AD32.

Inhibitory Effect of Polyinosinic: Polycytidylic Acid on the Growth of Transplantable Mouse Mammary Carcinoma

Summary This study was designed to test the effect of the sequential administration of poly I: poly C on the growth rate and morphology of DBA mouse mammary adenocarcinoma. Treatments with poly I: poly C (150 μg ip per dose) started (a) 24 hr after implantation; (b) when the size of tumors reached 0.6—1.0 cm3, or (c) 1.8—2.0 cm3. Controls were injected with 0.15 ml phosphate-buffered saline (placebo). In all groups the treatment continued at 48-hr intervals for 18—22 days. Treatments starting 24 hr after implantation resulted in a temporary arrest of the growth of tumor implants followed by a significantly decreased volume-doubling time (for tumors 0.5 and 1.0 cm3 in size p <0.001). The treatment of established tumors was more effective in small tumors. The fractional survival of tumor tissue was significantly lower in tumors measuring 0.6—1.0 cm 3 (0.070) than in tumors 1.8—2.0 cm3 in size (0.231). All groups of mice treated with poly I: poly C showed a significantly longer survival time (p < .01). Increased interferon levels were observed after the first injection of poly I: poly C but not after a series of injections. The regression of tumors was most significant at the beginning of treatment. Extensive necrotic lesions were observed in histologic sections of tumors treated with poly I: poly C. There was no morphologic evidence suggesting the damage of the tumor tissue by induced cell-mediated immune response, and there was no indication that lymphocytes play some crucial role in the genesis of the inhibitory effect of poly I: poly C on isologous DBA tumors. The authors express appreciation to Dr. J. Vilcek, Department of Microbiology of the New York University Medical Center for performing the interferon assays and to Dr. Samuel Baron, of the National Institutes of Health, Bethesda, MD for reading the manuscript and comments.

Intraperitoneal Topoisomerase-I Inhibitors: Preliminary Findings with 9-Aminocamptothecin

Abstract: The i.p. administration of topoisomerase I (Topo I) inhibitors has a pharmacologic advantage over intravenous application, including preservation of the biologically active lactone form. In our ongoing study, patients have received 9‐amino‐20(S)‐camptothecin (9‐AC) i.p. on days 1, 3, 5, 8, 10, and 12, repeated every 4 weeks. The daily dose has been escalated to level IV of 1.5 mg/m2 (9.0 mg/m2 per course), median of 3 cycles, range 1–4, with a reversible Grade 3 neutropenia in one patient. Responses included one CR (resolution of a pleural effusion), two patients without progressive disease (PD), two not evaluable, and two patients too early for evaluation. The area under the curve (AUC)ip/AUCpl ratio (pharmacologic advantage) ranged from 7.6 to 16.5 on average, and, using nonlinear modeling, the pharmacologic decay data were fit to one‐ or two‐compartmental models. Overall, a 9‐AC i.p. application is well tolerated and anticipated to be an active regimen against i.p. malignancies, particularly those known to be sensitive to systemic Topo‐I inhibitors.

Phase I and pharmacologic study of i.p. 9-aminocamptothecin given as six fractions over 14 days.

We sought to define the tolerance of 9-amino-20(S)-camptothecin (9-AC) when given by the i.p. route to patients with cancer in the peritoneal cavity consisting of nodules that did not exceed 1 cm in maximum diameter. 9-AC was given in six fractions over 12 days, at doses ranging from 1.25 to 13.5 mg/m2 in cycles repeated every 28 days. Dose escalations after the first two dose levels took place in cohorts of three patients, with expansion of the dose level once a dose-limiting toxicity (DLT) was encountered. All patients had blood and i.p. pharmacokinetic (PK) analysis during cycle 1 of each dose level. Topoisomerase (Topo) I signal was serially measured in peripheral blood mononuclear cells (PBMCs) in blood and cells collected in i.p. cytologic washings. Twelve patients received 31 cycles of 9-AC. Tolerance to repeated i.p. drug administration was generally excellent. The DLT was neutropenia encountered at the highest dose level in two patients, whereas the dose of 9 mg/m2 was well tolerated. The DLTs were associated with peak plasma levels ranging from 47 to 81 ng/ml and also depletion of Topo I in PBMCs. The i.p.:plasma AUC ratio (±SD) was 11.5 (±3.8). Two patients had objective evidence of clinical benefit and only one of seven patients deemed evaluable for response had progressive disease. We conclude that i.p. 9-AC demonstrates excellent local tolerance at a dose and schedule associated with evidence of systemic effects. A dose of 9 mg/m2/cycle administered in a schedule of six divided fractions is suitable for further evaluation against tumors involving primarily the peritoneal cavity.