Efficacy and clinical cross-resistance of a new combination therapy (AMSA/VP16) in previously treated patients with acute nonlymphocytic leukemia

Post-remission therapy of adult acute myeloid leukaemia: one cycle of high-dose versus standard-dose cytarabine. Leukaemia Project Group of the Swiss Group for Clinical Cancer Research (SAKK)

BACKGROUND

Intensification of post-remission therapy improves the cure rate of acute myeloid leukemia (AML) but is often accompanied by unacceptable toxicity. From 1985 to 1992 the Swiss Group for Clinical Cancer Research (SAKK) performed a randomized phase III trial to evaluate the effectiveness of one single postremission course of high-dose cytarabine (HDAC) in terms of leukaemia-free and overall survival in adults with de novo AML.

PATIENTS AND METHODS

Adult (15-65 years) AML patients in remission after two induction courses were randomly assigned to one consolidation course either with standard (SDAC: 100 mg/sqm 24 hours infusion over seven days) or with high-dose cytarabine (HDAC: 3000 mg/sqm every 12 hours as one-hour-infusion for six days). In addition, both arms included daunorubicin (45 mg/sqm daily on days 1 to 3). Thereafter, patients were observed without maintenance until relapse.

RESULTS

After two induction courses 208/276 eligible patients achieved remission (CR: 169, 61%, PR: 39, 14%), 41 were resistant (15%) and 20 died early (7%). Seventy-one patients in remission were not randomized. One hundred thirty-seven were randomized in CR/PR (67 SDAC, 70 HDAC). 4/70 patients randomized to HDAC did not receive it. Treatment-related mortality in HDAC was 1.4% (1/66). WHO grade 3-4 toxicities occurred in 14/67 SDAC and in 38/66 HDAC patients (P < 0.0001). The median event free survival was 10.8 (SDAC) vs. 12.2 months (HDAC; P = 0.18). The median overall survival was 24.6 (SDAC) vs. 32.6 months (HDAC; P = 0.07). Although statistically uncertain, HDAC reduced the hazard of progression (hazard ratio: 0.69, P = 0.08) and of death (hazard ratio: 0.70, P = 0.13). For 112 patients stratified as CR the estimated four-year disease-free survival was 25% (+/-6%) with SDAC and 37% (+/-6%) with HDAC (P = 0.09). The overall survival rates at four years were 38% (+7%) and 48% (+7%), respectively (P = 0.10). In multivariate analysis HDAC significantly reduced the hazard of relapse by 39% compared to SDAC (hazard ratio = 0.61, 95% CI: 0.37-0.99; P = 0.049).

CONCLUSIONS

We conclude that early consolidation of adult AML in CR with a single course of HDAC is superior in terms of outcome to one cycle of SDAC. The results of our intensive, single course HDAC group compare favourably with less intensive, repetitive HDAC cycles, suggesting that Ara-C dose intensity may be more important than total dosage. In addition, our treatment strategy is much less toxic and less expensive.

Etoposide: twenty years later

Since the beginning of its clinical development 20 years ago, etoposide has become an important and widely used agent in clinical oncology. Its integral role in the treatment of germ cell tumors and small-cell lung cancer seems unlikely to diminish in the future, and its use in non-Hodgkin's lymphoma and in various high dose regimens will probably continue to increase. Active investigation continues regarding the optimal dose and schedule of etoposide, and it is likely that these investigations will result in further improvement of its clinical activity in patients with sensitive tumor types. Continued clinical investigation may result in the identification of active etoposide containing combination regimens for ovarian cancer, breast cancer, and some of the childhood malignancies. Exciting possibilities for the future include exploration of etoposide in combination with the topoisomerase I inhibitors, as well as the development of drugs to reverse drug resistance. During the next 10 years, the applications and importance of this unique drug will continue to increase.

Etoposide: current status and future perspectives in the management of malignant neoplasms

Etoposide has demonstrated highly significant clinical activity against a wide variety of neoplasms, including germ-cell malignancies, small-cell lung cancer, non-Hodgkin's lymphomas, leukemias, Kaposi's sarcoma, neuroblastoma, and soft-tissue sarcomas. It is also one of the important agents in the preparatory regimens given prior to bone marrow and peripheral stem-cell rescue. Despite its high degree of efficacy in a number of malignancies, the optimal dose, schedule, and dosing form remain to be defined. It is possible that continuous or prolonged inhibition of the substrate, i. e., topoisomerase II, may be the key factor for the cytotoxic effects of etoposide. Clinical studies have shown the activity of etoposide to be schedule-dependent, with prolonged dosing, best accomplished by the oral dosing form, offering a therapeutic advantage. This benefit awaits validation by prospective randomized studies, some of which are in progress. Recent clinical investigations have focused on the use of etoposide in combination with (a) cytokines to ameliorate myelosuppression, the dose-limiting toxicity of etoposide; (b) agents such as cyclosporin A and verapamil to alter the p-glycoprotein (mdr1) function; and (c) topoisomerase I inhibitors to modulate the substrate upon which it acts. There is continued interest in the development of etoposide to its maximal clinical dimensions and in the examination of alternative biochemical and mechanistic approaches to further our understanding of this highly active agent.

Etoposide in leukemia

Etoposide (VP16-213, NSC 141540) induces a complete response (CR) in 15% to 25% of previously treated patients with acute nonlymphocytic leukemia (ANLL) when used as a single agent. Etoposide has been used successfully in combination with cytarabine, daunorubicin, and amsacrine for salvage and consolidation therapies. Previously untreated ANLL patients 15 to 70 years of age were randomly assigned to cytarabine (100 mg/m2) on days 1 to 7 plus daunorubicin (50 mg/m2) on days 1 to 3 (7-3) or to the same drugs plus etoposide (75 mg/m2) on days 1 to 7 (7-3-7). Patients achieving a CR received two consolidation courses (5-2, attenuated 7-3 or 5-2-5). Among 264 eligible patients, there was a 56% CR rate with 7-3 therapy and a 59% CR rate with 7-3-7 therapy. Remission duration was significantly improved with 7-3-7 (median, 12 months with 7-3 and 18 months with 7-3-7; P = 0.01), but survival was not. Subset analysis in patients younger than 55 years of age revealed prolonged remission (median, 12 months with 7-3 and 27 months with 7-3-7; P = 0.01) and survival (median, 9 months with 7-3 and 17 months with 7-3-7; P = 0.04) with the 7-3-7 regimen. Hematologic toxicity was similar for both regimens during induction, but significantly more severe for 7-3-7 during consolidation therapy. Etoposide is active in ANLL and prolongs remission when used in induction therapy.

Etoposide in acute leukemia. Past experience and future perspectives

Etoposide as a single agent is active in relapsed and refractory acute myelogenous leukemia (AML), with complete responses (CR) rates of 10% to 25%. The drug has been safely combined with cytarabine, azacytidine, vinca alkaloids, and anthracyclines, inducing remission rates of 20% to 60% in patients with previously treated AML. The experience with etoposide in acute lymphoblastic leukemia is less extensive, but the drug seems to be active in combination with cytarabine or aclacinomycin. In addition, etoposide is combined with cytarabine and anthracyclines for the primary treatment of AML. The response rates thus achieved are comparable with those obtained with standard regimens. A Phase I/II trial was initiated to study the efficacy of the NOVE combination (mitoxantrone [10 mg/m2/d, days 1 to 5] plus etoposide [100 mg/m2/d for 3, 4, or 5 days] in patients with refractory AML. The results showed that extended duration of etoposide administration is associated with higher CR rates. Overall, a CR rate of 43% was achieved in 61 patients. A sequential regimen with IDAC (idarubicin/cytarabine) and NOVE was designed for primary treatment of adult patients with AML. Cycles of IDAC or NOVE are applied depending on response. The results of the pilot study with this strategy were encouraging with 18 of 20 patients achieving CR. Further studies are under way to verify the efficacy of this strategy.

Effects of amsacrine in combination with other anticancer agents in human acute lymphoblastic leukemia cells in culture

Effects of amsacrine in combination with other anticancer agents at ID80 were evaluated by cell growth assay using a human T-cell leukemia cell line (MOLT-3). The data were analyzed with the aid of an improved isobologram, using the concept of an envelope of additivity. A supra-additive effect was observed for amsacrine in combination with cytosine arabinoside and mitoxantrone. An additive effect was observed in its combinations with bleomycin, CPT-11, cisplatin, daunorubicin, doxorubicin, etoposide, 5-fluorouracil, homoharringtonine, mitomycin C, or vincristine. 6-Mercaptopurine had an additive effect with amsacrine at ID80 but a sub-additive to protective effect at ID90. A sub-additive to protective effect was shown for amsacrine in combination with methotrexate. These data suggest that cytosine arabinoside and mitoxantrone are the best of the anticancer agents we studied for use in combination with amsacrine. Bleomycin, cisplatin, CPT-11, doxorubicin, cytosine arabinoside, homoharringtonine, mitomycin C, and vincristine also yielded favorable results when administrated simultaneously with amsacrine. Simultaneous administration of amsacrine with 6-mercaptopurine and methotrexate is not appropriate. If amsacrine is combined with 6-mercaptopurine and methotrexate, other suitable schedules should be explored. These results may provide a rationale for the design of clinical protocols combining amsacrine with other anticancer agents.

Etoposide. Current and future status

Etoposide (VP-16-213) is an antineoplastic agent with demonstrated efficacy against a broad spectrum of human malignancies, including testicular, germ cell, lung, and other cancers. Etoposide can be synergistic with other agents. As part of combination chemotherapy, etoposide has become a so-called standard in therapies for testicular cancer and small cell lung cancer. Its activity in tumors such as lymphoma and leukemia, as well as solid tumors, identifies etoposide as a highly important chemotherapeutic agent. Cellular and animal models have shown that the cell kill and tumor response depend on both dose and time of exposure. Recent clinical studies again show that dose and schedule of etoposide can have important effects on clinical response to the drug. Further research should now continue: (1) on the use of etoposide as part of initial therapy in several cancers, and (2) in higher doses and prolonged schedules to optimize this agent's potential.

Pharmacokinetics and toxicity of two modalities of etoposide infusion in metastatic non-small-cell lung carcinoma

The pharmacokinetics and toxicity of two schedules of etoposide administration were studied in 19 patients suffering from metastatic non-small-cell lung cancer. Ten subjects received a 72-h continuous venous infusion (CVI) of 360 mg/m2 etoposide, and nine were given a daily dose of 120 mg/m2 for 3 consecutive days. In the two groups 80 mg/m2 cis-diamminedichloroplatinum (II) (CDDP) was infused on day 1. With CVI, the steady-state plasma concentration was reached 12-24 h after the start of the treatment. The plasma elimination rate showed a biexponential decay curve in both groups. No significant difference between total body clearance and the beta-phase volume of distribution was noted between the two modalities of administration. No relationship was found between biological and pharmacokinetic parameters.

Induction chemotherapy for newly diagnosed acute myeloid leukaemia using a regime containing cytosine arabinoside, daunorubicin and etoposide

A total of 46 patients with previously untreated acute myeloid leukaemia were treated with an induction regimen consisting of 100 mg/m2 cytosine arabinoside given daily by 18-h i.v. infusion for 7 days, 50 mg/m2 daunorubicin given daily by i.v. bolus injection for 3 days and 75 mg/m2 etoposide given daily by 1-h i.v. infusion for 7 days. In all, 30 patients (67%) went into complete remission and were given further consolidation and maintenance chemotherapy. Of the 31 complete responders, 15 (48%) relapsed. The median disease-free survival of the 31 complete responders and the median overall survival of all 46 patients were 25 and 14 months, respectively. None of the clinical characteristics, which included sex, age, FAB morphology, extramedullary disease and initial WBC count, predicted the clinical response. Myelosuppression was the major toxicity and non-haematological side effects were acceptable. The regimen appeared to have acceptable toxicity, and its efficacy was comparable with that of standard regimens.

Intermediate-dose cytosine arabinoside and amsacrine. An effective regimen with low toxicity in refractory acute nonlymphocytic leukemia

Results of remission induction therapy in refractory acute nonlymphocytic leukemia (ANLL) has been improved since the introduction of high-dose cytosine arabinoside. However, the toxicity of these regimens attributes to an early death rate of about 20% to 30%. The authors treated 37 poor-risk patients with ANLL with intermediate-dose cytosine arabinoside and amsacrine for remission induction. One consolidation course and no maintenance therapy was given. Eleven of 19 patients with a first relapse entered complete remission (58%); ten of 15 patients in this group older than 50 years were complete responders (67%). Median duration of second remission was 8.2 months (range, 2-14). Three of 13 patients with primarily resistant disease had a complete remission (23%), but there was no response in five patients with a myeloid blastic phase of chronic myelogenous leukemia. Side effects of this remission induction regimen were mild; no cardiac, pulmonary, or central nervous system toxicity was observed. Five patients (14%) died during the remission induction phase, three from complications during aplasia and two from refractory leukemia.

Treatment strategies in acute myeloid leukemia (AML). B. Second line treatment

The strategy for treatment of relapsed or refractory acute myeloid leukemia must primarily be based on the patient's age and clinical condition as well as on the stage of the disease. Accordingly, the general decision between an intensive approach including high-dose chemotherapy or possibly immediate allogeneic bone marrow transplantation versus less-aggressive palliative treatment will precede the selection of the most appropriate salvage regimen. In patients qualifying for intensive second-line chemotherapy the duration of the first remission and the number of relapses provide the means to discriminate between refractoriness or maintained responsiveness to conventional protocols. More than 50% of patients with first relapses after 6-12 months remission duration will respond to standard therapy again and should therefore not be entered on investigational agents with unproven antileukemic activity. The latter seems deeply warranted, on the other hand, for early relapses, second recurrences and resistant first relapses with a remission rate of less than 30% after conventional regimens. These guidelines not only provide an objective rationale for selecting the most appropriate strategy at relapse in individual patients. Furthermore, they facilitate interstudy comparisons and a better judgement of different treatment protocols.

Etoposide and teniposide in the treatment of acute leukemia

Etoposide and teniposide are semi-synthetic glucoside derivatives of podophyllotoxin with a documented anti-tumour activity in various types of malignant diseases. It was an early observation that these epiphodophyllotoxins were efficacious in hematological malignancies such as lymphomas and leukemias. In this report the clinical evidence supporting the activity of etoposide and teniposide in acute lymphoblastic (ALL) and non-lymphoblastic leukemia (ANLL) is reviewed. Unlike podophyllotoxin, etoposide and teniposide do not appear to affect microtubular function nor arrest cells in mitosis. These epiphodophyllotoxins, like other DNA intercalating agents, have topoisomerase II as their target. Most studies with etoposide have been performed in ANLL and with teniposide in ALL. This choice seems to be rather arbitrary and is better explained by traditional reasons than actual study results. The data in acute leukemias are partly flawed by the absence of certain prospective comparative trials. However, the current information on etoposide clearly shows that this agent has substantial activity in ANLL and may well be incorporated into front-line regimens and the same is true for teniposide in the treatment of ALL. Nevertheless, based on available literature, there are no convincing data to the author's mind to support that one of these agents is superior to the other in the treatment of acute leukemias.

Amsacrine, cytarabine and etoposide in the treatment of bad prognosis acute myeloid leukemia

Thirty-seven patients (median age 50 yr, range 17-82) with acute myeloid leukemia (AML) received intensive induction treatment with amsacrine, cytarabine and etoposide in combination. Nine of the patients were refractory to previous induction therapy, 15 relapsed during or after treatment with daunorubicin and cytarabine, 13 had AML after previous hematologic disorders. Eleven of the patients with AML after previous hematologic disorders had been treated with cytotoxic drugs. Toxicity was substantial, but complete remission (CR) was achieved in 33% of patients with refractory AML, 47% of patients with AML in relapse, 54% of patients with AML after antecedent blood disorder. CR duration was 15 weeks (median). Patients with AML of FAB types M4 and M5 entered remission more often (70%) than patients with other AML types (37%).

Effective reinduction therapy for childhood acute nonlymphoid leukemia using simultaneous continuous infusions of teniposide and amsacrine

The combination of teniposide (VM-26) and amsacrine (AMSA) was evaluated in a dose-finding and efficacy study in 58 patients with relapsed or refractory acute leukemia. Both agents were given as simultaneous continuous infusions for 72 h through separate i.v. lines. All patients were evaluable for toxicity and 57 were evaluable for response; only 2 of 20 with acute lymphoblastic leukemia (ALL), acute mixed-lineage leukemia, or chronic myelogenous leukemia in blast crisis achieved a complete remission (CR). More encouraging was a second-remission rate of 43% (13 complete and 3 partial) in the 37 patients with acute nonlymphoid leukemia (ANLL). Responses occurred only in patients who received VM-26 doses of greater than or equal to 200 mg/m2 per day and AMSA doses of greater than or equal to 100 mg/m2 per day. Thus, the CR rate for relapsed ANLL patients who received the higher doses of both agents was 40% (13 of 33). All responders had previously received epipodophyllotoxin therapy and 40% had also received AMSA. All but one patient had severe leukopenia (less than 2.0 x 10(9) leukocytes/l) and thrombocytopenia (less than 50.0 x 10(9) platelets/l) as a results of therapy. Severe mucositis (grade 3 or 4) was the dose-limiting toxicity. Our results indicate that VM-26 plus AMSA, given by continuous infusion, is effective in the treatment of ANLL. Further phase II studies should consider using VM-26 at 200 mg/m2 per day and AMSA at 100 mg/m2 per day, but the best administration schedule remains unclear.

Treatment of refractory acute myeloid leukemia with mAMSA and VP 16-213 in combination: results of a clinical phase I/II study

Twenty patients with refractory AML were treated with mAMSA and VP 16-213 in combination to assess the toxicity and anti-leukemic activity of the two-drug regimen. Refractoriness was defined according to the response to induction therapy consisting of 6-thioguanine, cytosine arabinoside and daunorubicin (TAD9) and the duration of the preceding remission. Patients were eligible for AMSA/VP 16-213 if they were primary non-responders against two TAD9 induction courses, had early relapses within the first six months, were nonresponders to one additional TAD9 course at later relapses or were at second or subsequent relapses. Therapy consisted of a five-day course of mAMSA 210 mg/m2/d on days 2, 3 and 4. VP 16-213 was applied on days 1 and 5 by a 1-h infusion of 100 mg/m2 followed by a 23 h infusion, the dosage of which was escalated in three steps from 110 mg/m2 over 200 mg/m2 to 230 mg/m2 in subsequent patients. Even at the highest dose of VP 16-213, toxicity was mild to moderate except for mucositis of grade III after two cycles and severe intrahepatic cholestasis in one case. Four of the 20 patients died within the first three weeks after the onset of treatment and were not evaluable for the assessment of antileukemic efficacy. From the remaining 16 patients five achieved partial remissions while no complete remission was obtained. Four of the five PR occurred in the eight patients with primary TAD9 resistance. These data indicate that AMSA/VP 16-213 reveals a moderate toxicity only, and that the combination may not be completely cross-resistant with TAD9. The overall anti-leukemic activity is limited however, and seems inferior compared to other presently available salvage regimens in refractory AML.

Etoposide in leukemia, lymphoma and bone marrow transplantation

Etoposide, an epipodophyllotoxin structurally related to vincristine, is active in solid tumors. Trials of etoposide in hematologic malignancies, particularly leukemia and lymphoma, were initiated in 1973. Subsequent studies indicate that etoposide, either as a single agent or in combination with other drugs, is active in acute myelogenous leukemia, non-Hodgkin and Hodgkin lymphoma. Etoposide may be effective in acute lymphoblastic leukemia, but it is inactive in chronic myelogenous leukemia. The major toxicity of etoposide is myelosuppression. Non-hematologic toxicity is relatively mild at doses up to 2000 mg/m2. This feature favors its use in high dose regimens such as those employed before bone marrow transplantation. Preliminary studies of etoposide in autologous bone marrow transplantation in lymphoma and Hodgkin disease are promising. Studies of high dose etoposide in combination with other chemotherapeutic agents or in the context of bone marrow transplantation are in progress.

Chemotherapy for relapsed and resistant acute nonlymphoblastic leukemia. Effect of ATA, an amsacrine-containing regime

Twenty-nine evaluable patients with acute nonlymphoblastic leukemia (ANLL), either in relapse or resistant to initial induction therapy (ara C, daunorubicin + etoposide), received the ATA regime consisting of 100 mg/m2 per day Ara C by i.v. infusion for 4-5 days, 100 mg/m2 per day thioguanine orally for 4-5 days, and 100 mg/m2 per day amsacrine i.v. for 2-5 days. Each patient received 1-6 courses (median, 2) of the regime. There were 7 (24%) complete responders, and their duration of responses were 2, 2, 2, 5, 9+, 19, and 24+ months. The complete remission (CR) rate of patients who had a previous CR beyond 6 months (6/13, 46%) was significantly better (X2 = 4.25, p less than 0.05) than that of those who had previously relapsed within 6 months or were refractory to primary induction chemotherapy (1/16, 6%). The two groups of patients had similar patterns of treatment failure. Myelosuppression was the major toxic side effect, and nonhematological toxicities were mild and acceptable.

Prognostic significance of agar and liquid cultures in AML patients before treatment, early postinduction and in remission

In the present study, the growth and differentiation capacity of myeloid leukemic cells in agar and liquid cultures have been investigated in relation to their prognostic significance for treatment outcome and early detection of relapse. Prior to induction therapy, leukemic cells failed to differentiate and the colony or cluster number did not correlate with response to treatment. Seventeen to 42 days after induction, patients with BM cells producing greater than 10 colonies or greater than 30 clusters resp. had a high likelihood of achieving a complete remission. Cells from refractory patients had a significantly impaired differentiation capacity. During remission, a colony number greater than 50 was significantly associated with a high probability to remain in further remission for greater than 3 months. An impaired differentiation was significantly associated with the likelihood of relapsing within 3 months. In the light of these results, agar and liquid cultures appear to be useful for monitoring the effect of induction chemotherapy and detecting patients likely to relapse.