N-(phosphonacetyl)-L-aspartate (PALA) in advanced soft tissue sarcoma: a phase II trial of the EORTC soft tissue sarcoma group

Phase II trial of 6-diazo-5-oxo-L-norleucine versus aclacinomycin-A in advanced sarcomas and mesotheliomas

Ninety-eight patients with previously-treated advanced soft tissue sarcoma, bone sarcoma, or mesothelioma were randomly assigned to one of two intravenous single-agent treatment regimens, either 6-diazo-5-oxo-l-norleucine (DON; brief infusions of 50 mg/m2/day for 5 consecutive days every 4 weeks) or aclacinomycin-A (ACM-A, as 30-min infusions of 100 mg/m2 or 85 mg/m2, administered every 3 weeks). Of 43 patients who were evaluable for response, survival and toxicity, there were two responses (5%) produced by ACM-A; one in a male with mesothelioma, and one in a female with malignant fibrous histiocytoma. None of the 36 evaluable patients treated with DON developed an objective tumor response. Median survival was 4.8 months in the DON treatment arm, and 6.8 months in the ACM-A treatment arm. No patients on the DON arm experienced lethal or life-threatening toxicities, and severe toxicities resulting from this treatment included nausea and emesis (10%), stomatitis (2%), gastrointestinal toxicity (2%), and anemia (2%). Moderate toxicities included vomiting (24%), hematologic toxicity (24%), neurologic toxicity (7%), diarrhea (7%), mucositis (5%), fever (5%), palpitations (2%), hepatotoxicity (2%), bleeding (2%) and edema (2%). Fifteen percent experienced at least one severe reaction, and 63% experienced at least one moderate or greater toxicity. ACM-A was associated with four cases of life-threatening myelosuppression (7%); severe toxicities included myelosuppression (11%), neurologic toxicity (4%), diarrhea (2%), respiratory toxicity (2%), pain and muscle spasms (2%), edema (2%), and ulceration following extravasation (2%).(ABSTRACT TRUNCATED AT 250 WORDS)

The role of low-dose PALA in biochemical modulation

Phosphonacetyl-L-aspartate (PALA) is a rationally-synthesized analog of the transition-state intermediate in the formation of carbamyl aspartate from carbamyl phosphate and aspartic acid by aspartate carbamyl transferase (ACTase). PALA is thus a potent inhibitor of the enzyme (Ki about 10(-8) M for ACTases of various origins), which in whole cells blocks the de novo synthesis of pyrimidines. In vivo, low doses of PALA inhibit whole body pyrimidine synthesis. While this action is cytotoxic in vitro, extensive human testing demonstrates that PALA alone is devoid of selective antitumor activity. Recent interest in the therapeutic action of PALA derives from the demonstration that its action potentiates the cytotoxicity of several cytotoxic drugs, notably 5-fluorouracil (5-FU). Results from clinical trials of PALA and 5-FU in combination in colorectal cancer suggest that biochemical modulation with regimens which follow the principles determined in preclinical studies may enhance the efficacy of current therapy.

Metabolism and action of amino acid analog anti-cancer agents

The preclinical pharmacology, antitumor activity and toxicity of seven of the more important amino acid analogs, with antineoplastic activity, is discussed in this review. Three of these compounds are antagonists of L-glutamine: acivicin, DON and azaserine; and two are analogs of L-aspartic acid: PALA and L-alanosine. All five of these antimetabolites interrupt cellular nucleotide synthesis and thereby halt the formation of DNA and/or RNA in the tumor cell. The remaining two compounds, buthionine sulfoximine and difluoromethylornithine, are inhibitors of glutathione and polyamine synthesis, respectively, with limited intrinsic antitumor activity; however, because of their powerful biochemical actions and their low systemic toxicities, they are being evaluated as chemotherapeutic adjuncts to or modulators of other more toxic antineoplastic agents.

Review of the clinical trials activity of the Soft Tissue and Bone Sarcoma Group of the European Organization for Research and Treatment of Cancer

Despite the low incidence of sarcomas, the Soft Tissue and Bone Sarcoma Group has established itself as one of the more active cooperative groups of the European Organization for Research and Treatment of Cancer. Performing over a 10 yr period three phase III protocols (total entry 750 patients), three randomized phase II studies (464 patients), a pilot combination study (185 patients), and 12 phase II studies (406 patients). The new randomized phase III protocol for advanced soft-tissue sarcoma will provide an interesting test of the validity of the current membership policy, which has not discouraged the participation of enthusiastic new members. For extremity sarcomas, improved surgical techniques have increased the number of patients retaining functional limbs but have maintained excellent rates of local control. However, systemic metastasis remains a significant problem and presents a challenge for future adjuvant studies.

The treatment of soft tissue sarcomas with focus on chemotherapy: a review

Radical surgery remains the most effective treatment of soft tissue sarcomas. The postoperative addition of radiotherapy appears to reduce local recurrence in extremity lesions. To date, there are still only two drugs with major activity as a single agent in the treatment of soft tissue sarcomas: doxorubicin (DX) and ifosfamide (IFX). Doxorubicin should be administered preferably as 3-weekly bolus injections at doses higher than 60 mg/m2 because of its dose-response relationship. In combination chemotherapy ADIC and CYVADIC are probably the best choice. Although there are no definite data on increased activity with the addition of cyclophosphamide (CTX) and vincristine (VCR) to ADIC, we prefer CYVADIC because of the higher reported complete response rate. A limited number of patients with soft tissue sarcomas achieving a complete response with chemotherapy, will probably be cured, and for this reason it is important to aim at achieving a complete response. Preoperative intraarterial chemotherapy in locally advanced soft tissue sarcomas may further improve survival results, but before definite conclusions can be drawn, this technique should be investigated in randomized studies. Postoperative adjuvant chemotherapy should still be considered investigational, as no advantage has been observed in head, neck and trunk lesions, while data on extremity lesions are still conflicting.

N-(phosphonacetyl)-L-aspartate (PALA) in advanced malignant melanoma: a phase II trial of the EORTC Malignant Melanoma Cooperative Group

Thirty-nine patients with measurable advanced malignant melanoma were entered in a phase II trial with PALA. Among the 36 evaluable patients there were 18 men and 18 women, with a median age of 53 yr (29-73) and a median performance status (Karnofsky) of 100 (50-100). Indicator lesion consisted essentially of soft tissue lesions (29 patients) and/or lung metastases (9 patients). Only three patients had received prior chemotherapy. PALA was given as a 60-min i.v. infusion at a daily dose of 2.5 g/m2 for two consecutive days. Courses were repeated every two weeks. A median number of 3 courses (2-8) were administered. Partial response (greater than 50%) was obtained in 4 patients for 6-17 weeks. Eight patients had stable disease after 3 courses of PALA and 24 had progressive disease. Toxic effects were generally mild to moderate and mainly included cutaneous toxicity, nausea and vomiting, stomatitis, and diarrhea. Myelosuppression was rare and negligible. It is concluded that PALA given at the dose schedule selected for this trial is fairly well tolerated and has borderline antitumor activity in good-risk patients with advanced malignant melanoma.