Phase II study of weekly edatrexate as first-line chemotherapy for metastatic breast cancer: a National Cancer Institute of Canada Clinical Trials Group study

Phase II trial of 10-EDAM in the treatment of metastatic breast cancer

INTRODUCTION

This phase II trial was conducted to assess the efficacy and safety of 10-Ethyl-10-Deaza-Aminopterin (10-EDAM), a folate antagonist, in metastatic breast cancer patients who had received no more than one prior chemotherapy regimen.

METHODS

Fifty-five patients were treated on an initial weekly dose 80 mg/m(2) of 10-EDAM. Patients who had received a prior chemotherapy regimen in the adjuvant setting (group 1) were considered separately from patients who had received a prior chemotherapy regimen in the metastatic setting (group 2).

RESULTS

The response rate for both groups combined was 18%, and median time to progression was 3 months. Median overall survival was 12 months. Treatment was associated with common chemotherapy-related toxicities, such as 25% grade three or four neutropenia and 20% grade three or four stomatitis.

CONCLUSION

In patients with metastatic breast cancer who had received one prior chemotherapy regimen, 10-EDAM was well tolerated. In general, while definite antitumor activity was documented, time to progression was brief.

Phase I trial of edatrexate in advanced breast and other cancers

Edatrexate (EDX) (10-ethyl-10-deazaaminopterin or 10-EDAM) is an analogue of methotrexate with improved pre-clinical antitumor activity, more selective cellular uptake, and with more extensive formation of intracellular polyglutamate metabolites. A phase I trial in advanced cancer using EDX was initiated to determine the toxicities associated with the use of a biweekly schedule of intravenous EDX, and to carry out a dose escalation to define the maximum tolerated dose employing this schedule. Thirty-four patients were enrolled in this phase I trial. Thirty-three patients were treated in cohorts of at least three patients (except at one dose level, 210 mg m-2, where there were only two patients). Dose escalations of EDX were administered starting with 100 mg m-2, and progressing through 120, 140, 160, 180, 210, 240, and 270 mg m-2. Edatrexate was administered by intravenous infusion over 20 min, and cryotherapy using ice chips was given prophylactically for 5 min before, during, and 15 min after each EDX treatment. The dose-limiting toxicity could not be reached in this study because it had to be closed on account of competing protocols using EDX in combination regimens. Of note though, was that the delivered dose intensity at the 160 mg m-2 week-1, was higher than the previously used or recommended phase II doses. Anemia was mild and white blood corpuscle toxicity was mostly of grade 1 or 2. One patient had grade 4 neutropenia and one had grade 3 thrombocytopenia. Of the non-hematological toxicities, nausea, vomiting, and diarrhea were mild and tolerable. Mucositis, which was the dose-limiting toxicity in previous studies, was seen in 30% of the patients, but was predominantly a grade 1 toxicity. This could have been due to either the different schedule of EDX used in this study or the use of cryotherapy. Substantial antitumor effects were noted, with two near-complete complete responses at the 120 and 160 mg m-2 levels. Additionally, six partial responses and one minor response were observed, and stable disease was observed in seven patients. Despite achieving antitumor activity at different dose levels, a clear-cut dose response was not evident at the levels tested. We feel that the biweekly EDX schedule is a tolerable regimen, which allows a higher dose intensity than weekly administration, and that EDX is an active agent for the treatment of patients with metastatic cancer.

Monotherapy of Metastatic Breast Cancer: A Review of Newer Agents

Purpose. New agents for the palliative treatment of metastatic breast cancer have emerged in the 1990s. This review summarizes the response rates of these agents with an emphasis on recent findings, such as presentations from the 1998 Meeting of the American Society of Clinical Oncology.

Methods. The English medical literature was reviewed to identify clinical trials involving monotherapy for the treatment of metastatic breast cancer. Three agents—paclitaxel, vinorelbine, and docetaxel—are emphasized because their databases are extensive enough to allow interesting comparisons. Liposomal-encapsulated anthracyclines, losoxantrone, gemcitabine, oral surrogates of continuous-infusion fluorouracil, raltitrexed, LY 231514, edatrexate, topoisomerase I inhibitors, and trastuzumab are reviewed briefly.

Results. Many of the new agents produce response rates approaching or even surpassing those achievable with doxorubicin monotherapy. Compared with older agents, some new agents have improved or at least different safety profiles, and some are easier to administer.

Discussion and conclusions. The new agents offer useful therapeutic options that make them suitable for combining with each other and with older agents, which could result in more effective regimens for metastatic disease, and, ultimately, primary disease in the adjuvant setting. The chemotherapeutic paradigms governing the management of breast cancer for the past three decades are likely to change as we move into the 21st century.

Phase I trial of edatrexate plus carboplatin in advanced solid tumors: amelioration of dose-limiting mucositis by ice chip cryotherapy

PURPOSE

Edatrexate (10-Edam) is a methotrexate analog with improved intracellular transport, polyglutamation, and antitumor activity compared to the parent compound. Edatrexate shows schedule-dependent synergism with platinum compounds in preclinical studies. We performed a phase I trial to determine toxicities and establish the maximum tolerated dose (MTD) of edatrexate in combination with carboplatin. Based on the short initial plasma half-life of edatrexate, prophylactic ice chip cryotherapy was used to reduce the severity of mucositis.

PATIENTS AND METHODS

Forty-six chemotherapy-naive patients with advanced solid tumors were treated. Edatrexate was given weekly for 5 doses (50% on day 8), and then every other week, followed by carboplatin at a fixed dose of 350 mg/m2 on day 1 and then every 4 weeks for 8 cycles. Edatrexate dose was increased at increments of 10 mg/m2/dose level beginning at 60 mg/m2/week (range 60-120 mg/m2).

RESULTS

All patients were assessable for toxicity and response analysis. The median number of cycles administered per patients was 4. This combination chemotherapy regimen was well tolerated. Using ice chip cryotherapy, no grade IV mucositis was observed. Grade III mucositis occurred in only 7/46 pts and was not dose-related. Protocol-defined dose-limiting toxicity occurred at a edatrexate dose level of 120 mg/m2, yielding an MTD of 110 mg/m2. Responding tumor types included non-small cell and small lung cancer, head and neck cancer, and bladder cancer.

CONCLUSIONS

1 ) This phase I study demonstrated the safety and tolerability of this edatrexate and carboplatin combination. 2) Dose-limiting mucositis did not occur allowing escalation of edatrexate dose above levels previously achieved with this edatrexate dose schedule. This was most likely a result of prophylactic ice chip cryotherapy. 3) An edatrexate dose of 110 mg/m2 with ice chip cryotherapy is recommended for Phase II trials of this combination.

Antifolates: current developments

In summary, the problem of MTX resistance has been approached in a mechanistic fashion, based on the wealth of information generated over the years. To date, these strategies have produced several new classes of anticancer drugs, with a variety of anticipated and unanticipated mechanisms of action. Several of these have shown promising preclinical activity, and these are moving into more stringent testing in the clinic.

Schedule-dependent synergism of taxol or taxotere with edatrexate against human breast cancer cells in vitro

A new dihydrofolate reductase inhibitor, edatrexate (EDX), and the microtubule polymerization promotor, taxol (TXL) or taxotere (TXT), each have significant therapeutic activity against human breast cancer in clinical trials. Since they also have distinctly different mechanisms of actions and have mainly non-overlapping toxicities, they may be effective in combination in the treatment of this disorder. Schedule-dependent interactions between these taxanes and EDX against human breast adenocarcinoma cells (SK-Br-3) were quantitatively assessed in vitro to determine whether these interactions are synergistic or antagonistic. SK-Br-3 cells were grown as a monolayer in 96-well microplates. The dose-effect relationships of the drugs, singly and in combination, in inhibiting the growth over a 7-day period were determined by the SRB protein staining assays. Cell cultures were exposed to drug as a 3-h pulse at either 0-3 h or 24-27 h. Synergism or antagonism at different concentrations and at different effect levels were assessed with the median effect principle and the combination index-isobologram method using computer software. These methods were selected because they take into account both the potencies and the shape of the dose-effect curves. Exposure of cells to an equimolar combination of EDX + TXL (0-3 h) resulted in synergism at high effect levels. Pretreatment of cells with EDX (0-3 h) followed by TXL (24-27 h) showed even greater synergism in inhibiting cell growth. Moderate antagonism was observed with the reverse schedule. EDX + TXT (0-3 h) was additive, but pretreatment with EDX (0-3 hr) followed by TXT (24-27 h) showed synergism. However, the reverse order showed antagonism. Studies on another breast tumor cell line, ZR-57-1, also showed the schedule of EDX (0-3 h) + TXT or TXL (24-27 h) to be more synergistic than, the other two schedules examined. These results show potent schedule-dependent synergism of the combinations of TXL or TXT with EDX, and should form a rationale for designing clinical protocols utilizing these agents particularly for the treatment of breast cancer patients.

Radiation recall dermatitis induced by edatrexate in a patient with breast cancer

Enhancement of radiation injury to the skin and mucous membranes has been observed with a number of chemotherapeutic agents. A 32-year-old woman with metastatic breast cancer received local radiation therapy to the lumbosacral area. Six weeks later, systemic edatrexate therapy was initiated and a localized painful erythema with edema and a vesicular eruption occurred over the previous site of radiation therapy. Physicians should be aware that edatrexate can cause radiation recall, and that careful use of anti-inflammatory agents may allow continued chemotherapy treatment.

Clinical cooperative trials of the National Cancer Institute of Canada Clinical Trials Group Breast Cancer Site Group

For more than 10 years, the National Cancer Institute of Canada Clinical Trials Group (NCIC CTG) Breast Cancer Site Group has focused primarily on trials of adjuvant therapy and of investigational new drugs (IND). Four trials of adjuvant therapy in node-positive women have been completed, are active, or are about to begin. Investigational new drug (IND) studies have included Phase II trials of intravenous and oral menagaril, 10-EDAM (edatrexate), taxotere, and mifepristone (RU-486) as well as a Phase I/II trial of 5-fluorouracil (5-FU), doxorubicin, and vinorelbine (FAN); a Phase I/II trial of 5-FU, leucovorin, doxorubicin, and vinorelbine (super-FAN), all as first-line therapy for metastatic disease; and a Phase III study of vinorelbine plus doxorubicin versus doxorubicin alone as first- or second-line metastatic therapy. A proposed study with the European Organization for Research and Treatment of Cancer in locally advanced breast cancer will compare a standard NCIC CTG regimen of cyclophosphamide, epirubicin, and 5-FU (CEF) with epirubicin and cyclophosphamide granulocyte colony-stimulating factor (G-CSF), a more dose-intensive regimen. In addition, NCIC CTG is preparing a pilot of CEF with G-CSF to examine whether a substantially more intensive dosage can be given without added toxicity. NCIC CTG will also enter patients into a currently active Cancer and Leukemia Group B/Southwest Oncology Group randomized trial of intensive therapy versus more intensive therapy with bone marrow support in women younger than age 60 with 10 or more positive nodes. It is believed that optimizing the combination and timing of adjuvant hormonal and chemotherapy, exploring dose intensive approaches, developing investigational new drugs, studying the role of biologics, and tumor banking in conjunction with clinical trials remain important approaches for the future.

Effective combination therapy of metastatic murine solid tumors with edatrexate and the vinca alkaloids, vinblastine, navelbine and vindesine

Studies are described in which a new folate analogue, edatrexate (EDX), in combination with the vinca alkaloids, vinblastine (VBL), navelbine (NVB) or vindesine (DVA) was evaluated against E0771 mammary adenocarcinoma, T241 fibrosarcoma and the Lewis lung tumor. Each of the four agents when given individually to animals 3 days after transplant of these tumors resulted in increases in survival of 53-143%. The relative effectiveness of these agents was (in increasing order) VBL, NVB congruent to DVA, EDX, with no long-term survivors obtained with any. Combination therapy with EDX and vinca alkaloids required dosage attenuation but was still markedly more effective. Treatment of E0771 and T241 tumors with EDX and either NVB or DVA increased survival 3- to 4-fold compared with therapy with individual agents and yielded 40-70% long-term survivors, while EDX with VBL increased survival 2- to 3-fold and yielded 20-40% long-term survivors. Simultaneous or sequential (EDX given 24 h before vinca alkaloid) administration of combined therapy was equally effective. Sequential administration of these agents at the same doses in the reverse order was highly toxic and required further dosage attenuation which compromised efficacy. Effects of these combinations against the Lewis Lung tumor were not as pronounced and were somewhat schedule-dependent. Simultaneous administration of EDX with VBL, NVB or DVA increased survival 2- to 3-fold over that obtained with single agents alone and yielded 10-40% long-term survivors, while sequential administration increased survival < 2-fold over that obtained with single agents and yielded 0-20% long-term survivors. These results suggest that combined therapy with these agents in patients may have appreciable utility and provide a basis for further clinical trials.