Faculty Bibliography

Topoisomerase 1 (topo-1) inhibitors act on the target enzyme by forming 'cleavable complex,' a high molecular weight DNA protein adduct. The formation of such cleavable complexes results in depletion of the Mr 100,000 'free' topo-1 band detectable by Western blot. The objectives of this study were to determine the maximally tolerated dose of prolonged topotecan infusion in previously untreated and minimally pretreated patients. A secondary objective was to measure the effect of prolonged topotecan infusion on topo-1 levels in peripheral blood mononuclear cells (PBMCs) as a pharmacodynamic end point. In a prior Phase I study of 21-day topotecan infusion (H. Hochster et al., J. Clin. Oncol., 12: 553-559, 1994), the maximum tolerated dose for patients treated previously was 0.53 mg/m2/day for 21 days every 28 days. In this study, patients with no prior therapy were treated similarly at 0.7 mg/m2/day for 21 days, and doses were escalated in 0.1 mg/m2/day increments. Patients who had one prior chemotherapy regimen or radiation therapy to a portal of </=20 cm2 were entered at the 0.6 mg/m2/day level. Cohorts of four patients were entered until the maximum tolerated dose was determined. Peripheral blood was sampled weekly to obtain plasma topotecan drug levels and topo-1 levels in PBMCs by Western Blot. For previously untreated patients, the dose-limiting toxicity was myelosuppression at the dose of 0.8 mg/m2/day. Anemia was seen as a cumulative effect. Unexpected nonhematological toxicity was not observed. topo-1 level analysis by Western blot in 11 cycles with weekly measurements showed progressive decrement in the percentage of free topo-1 (compared to baseline value) during weeks 1, 2, and 3. The median percentage of decrease from baseline was 26% (P, not significant; Wilcoxon signed rank test) at week 1, 45% (P = 0.10) at week 2, and 77% (P = 0.016) at week 3. At week 4, off drug treatment, the median percentage of decrease from baseline was only 14%. Additional analysis of free topo-1 level as a function of both area under the curve (P = 0.005) and day of infusion (P = 0.003) demonstrated a significant relationship by regression analysis using a linear mixed effects model. In this Phase I study of topotecan prolonged infusion, hematological toxicity remained dose limiting without evidence of previously described nonhematological toxicity. The recommended Phase II dose is 0.7 mg/m2/day for 21 days every 28 days for previously untreated patients and 0.6 mg/m2/day for those with limited prior therapy. Western blot analysis of noncomplexed topo-1 in PBMCs sampled weekly showed a progressive depletion of free topo-1 over the 21 days of infusion, which reached statistical significance by week 3. Within 1 week of stopping infusion, topo-1 levels return to baseline. A strong correlation of topo-1 level with area under the curve and duration of infusion was demonstrated. These data suggest that prolonged administration of topo-1 inhibitory drugs results in sustained depletion of free topo-1 enzyme as measured by Western Blot analysis, which may be an important consideration in the clinical use of these agents. Direct randomized, comparative trials will be necessary to determine whether such schedules will improve therapeutic index and efficacy

A critical requirement for cancer vaccines is that they stimulate CD8+ T cell responses. In this study, we tested the ability of a polyvalent melanoma vaccine to induce CD8+ T cell responses to the melanoma associated antigens MAGE-3 and Melan A/MART-1. Fifteen HLA-A2+ patients with resected malignant melanoma were immunized with the vaccine s.c. every 2-3 weeks. CD8+ T cells in peripheral blood reacting to HLA-A2 restricted epitopes on MAGE-3 (FLWGPRALV) and Melan A/MART-1/(AAGIGILTV) were quantitated using a filter spot assay at baseline and following 4 immunizations. Vaccine immunization induced CD8+ T cells reacting to one or both of these peptides in 9 of the 15 (60%) patients. These cells were CD8+ and HLA-A2 restricted, as reactivity was abrogated by monoclonal antibodies (MAbs) to CD8 and class I HLA, but not by anti-CD4. All responding patients remained recurrence-free for at least 12 months (median 15 months, range 12 to >21 months), whereas melanoma recurred within 3-5 months in non-responders. The differences in outcome were unrelated to differences in disease severity or overall immunological competence between responders and non-responders. Our results demonstrate directly that MAGE-3 and Melan A/MART-1 can stimulate CD8+ T cell responses in humans, and suggest that these responses are protective and surrogate markers of vaccine efficacy

Topotecan, a topoisomerase-1 inhibitor, may have greater therapeutic index when given by prolonged infusion. In an earlier phase I trial of escalating low-dose infusion (MTD = 0.53 mg/m2/d x 21d) for previously treated pts (JCO; 12:553 1994), 3/6 heavily treated ovarian cancer pts responded. We administered 60 cycles of TPT to 16 pts in a phase II study starting at 0.4 mg/m2/d x 21 days. All pts had one prior platinum-containing chemotherapy regimen with progression or recurrence (early less than 6 mo vs later). All pts had PS 0-1, normal heme parameters and Creat less than 1.6. Measurable disease (greater than 2 cm on CT scan) was required. Four pts were able to be escalated to 0.5 mg/m2/d for 11 cycles and 6 were reduced to 0.3 in 15 cycles. Responses are presented in a table. Four pts had stable disease (3 still on rx), and 6 PD. Overall response rate is at least 37% (95% CI =12-62%). Hematologic toxicity included leukopenia and neutropenia gr 3 = 4 pts (7%) and gr 4 = 1 pt (2%) but no grade 3 or 4 thrombopenia. Eight pts required blood transfusions. Non-heme toxicity included grade 1 nausea = 7 pts and gr 2 =3 pts; grade 1 fatigue =5 and gr 1 alopecia = 4 pts. Two catheter related thromboses occurred; 2 had sepsis. Weekly PBMC topo-1 levels were obtained for pharmacodynamic studies (abstract submitted). This response rate is among the highest reported for second-line therapy of ovarian cancer and is seen in both platinum resistant and refractory disease. Data on these and additional pts currently being accrued will be presented. (C) American Society of Clinical Oncology 1997

PURPOSE: A phase II study of paclitaxel and cisplatin in patients with advanced breast cancer was performed to determine the objective response rate and make further observations about the toxicity of this regimen. PATIENTS AND METHODS: Patients were required to have histologically proven adenocarcinoma of the breast with no more than one chemotherapeutic treatment for advanced disease. Treatment consisted of paclitaxel 200 mg/m2 administered as a 24-hour intravenous (i.v.) infusion followed by cisplatin 75 mg/m2 i.v. Patients received granulocyte colony-stimulating factor (G-CSF) 5 micrograms/kg subcutaneously on day 3 until WBC recovery. Cycles were repeated every 21 days. Patients continued to receive therapy until disease progression or unacceptable toxicity. RESULTS: Forty-four patients entered the trial. Forty-two patients were assessable for response. Nineteen patients (43%) had no prior chemotherapy and 41 had no chemotherapy for metastatic disease. The median number of cycles administered per patient was five (range, one to seven). There were five complete responses (CRs) (11.9%) and 17 partial responses (PRs) (40.5%), with an overall response rate of 52.4% (95% confidence interval [CI], 36.4% to 68.0%). Nine patients had stage III disease. The response rate for this group was 66.7% (95% CI, 33.0% to 92.5%), with three CRs and three PRs. Among 35 patients with stage IV disease, there were two CRs and 14 PRs, with an overall response rate of 48.5% (95% CI, 30.8% to 66.5%). Overall, the median response duration was 10.6 months. Thirty patients (68%) developed transient grade 4 neutropenia. Cumulative neuropathy was the major dose-limiting toxicity. After five cycles of chemotherapy, 96% of patients had at least grade 1 neurotoxicity and 52% had at least grade 2 neurotoxicity. One patient had a toxic death after cycle 1 of therapy. CONCLUSION: The combination of paclitaxel and cisplatin as first-line chemotherapy for women with advanced breast cancer is an active regimen. However, the cumulative neurotoxicity was significant and dose-limiting in the majority of patients

Alpha interferon (IFN) has single agent activity in the treatment of metastatic malignant melanoma. Preclinical data suggests that cis-retinoic acid (cRA) may potentiate the activity of IFN. Clinical trials of this combination in the treatment of squamous cell carcinoma report higher response rates than that expected for IFN alone. We tested the activity of the combination of IFN and cRA in patients (pts) with metastatic malignant melanoma. 13 pts were treated with IFN 5 x 10 (6) units/m2 tiw and cRA 100 mg/kg/day. 11 pts were previously treated with chemotherapy; 2 had no prior treatment. Sites of metastases include: lung (9), liver (4), soft tissue (7), adrenals (2) nodes (2). 1 PR was seen in lung and adrenal mets (for 6 mo), 2 pts had stabilization of pulmonary mets for 2 mo. All other pts had progressive disease within 8 wk of beginning treatment. Toxicity was substantial. All pts experienced ECOG Grade 1-2 fatigue, myalgias, anorexia, stomatitis and cheilitis. Serum cholesterol and triglycerides became elevated in all pts. Dose reductions included: 1 pt 50% IFN for fatigue, 1 pt 50% cRA for stomatitis, 3 pts 50% cRA for hypertriglyceridemia. 1 pt discontinued therapy for decline in PS to ECOG Level 3. The mean duration of treatment was 8.8 wk; range (3 -28 wk). The combination of cRA and IFN in this study did not demonstrate any improvement over the single agent activity of IFN. (C) American Society of Clinical Oncology 1997

EDA is an analog of methotrexate which has clinical activity in a variety of solid tumors. We are studying EDA in combination with DOX to assess the toxicities and the maximally tolerated dose (MTD). Without G-CSF, the MTD was EDA 40 mg/m2 iv q 2 wk and DOX 30 mg/m2 iv q 4 wk. A 25% dose-escalation of both drugs resulted in dose-limiting neutropenia in 3/6 evaluable patients. Subsequently, G-CSF was added to the regimen on days 3-13. In addition, all patients received ice chip cryotherapy with EDA infusion. After these modifications, 6 patients (M/F; 5/1) have entered the trial. Median age 53 (range 44-61); median PS of 1. All had prior chemotherapy (2 greater than or equal to 2 regimens); 3 prior radiation. A total of 19 cycles were given. There were no significant toxicities noted during cycle 1 of chemotherapy with EDA 50 mg/m2 and DOX 37 mg/m2 + G-CSF. One patient developed grade 1 mucositis after cycle 4 requiring dose reduction and subsequent elimination of day 15 EDA. Despite this, he developed grade 3 mucositis and grade 4 neutropenia after cycle 7 requiring day 1 dose reduction of both EDA and DOX. Three patients have received at least 1 cycle of chemotherapy with EDA 62 mg/m2 and DOX 47 mg/m2 + G-CSF. There were no significant toxicities identified. The doses of both EDA and DOX can be escalated by the addition of G-CSF. Ice chip cryotherapy appears to reduce the severity of mucositis with this regimen. Dose escalation is continuing. Phase II studies are planned in soft tissue sarcoma and colon cancer. (C) American Society of Clinical Oncology 1997

The identification of effective adjuvants is critical for tumor vaccine development. Towards this end, we examined whether the immunogenicity of a melanoma vaccine could be potentiated by DETOX, an adjuvant consisting of monophosphoryl lipid A (MPL) and purified mycobacterial cell-wall skeleton (CWS). Nineteen patients with resected stage III melanoma were immunized with a polyvalent melanoma antigen vaccine (40 micrograms) admixed with DETOX, q3 wks x 4. Seven patients received vaccine + low-dose DETOX (10 micrograms MPL + 100 micrograms CWS) and 12 received vaccine + high-dose DETOX (20 micrograms MPL + 200 micrograms CWS). A non-randomized control group of 35 patients was treated similarly with 40 micrograms vaccine + alum. One week after the fourth vaccine immunization, melanoma antibodies were increased over baseline in 7/7 (100%) patients treated with vaccine + low-dose DETOX, 8/12 (67%) patients treated with vaccine + high-dose DETOX, and in 4/19 (21%) of vaccine + alum patients. For the entire DETOX group, the antibody response rate was 15/19 (79%) compared 4/19 (21%) in the alum group (p < 0.001). In contrast, a strong delayed-type hypersensitivity (DTH) response (> or = 15 mm increase in DTH response over baseline) was induced in 50% of the entire DETOX group versus in 47% of the alum group. Median disease-free (DF) survival for the entire DETOX group was 17.8 months compared with 32.1 months in the alum group (p < 0.05). In conclusion, DETOX markedly potentiated antibody but had little effect on DTH responses to melanoma vaccine immunization. It did not appear to improve disease-free survival in comparison to alum in this non-randomized study