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Eighty-two patients with Hodgkin's disease (H.D.) and 40 patients with Multiple Myeloma (M.M.) were HL-A typed. The results were compared with those of 255 healthy individuals of the same geographical area. In both diseases W18 (4cr) - belonging to the 4c-complex - was significantly increased.

Es werden klinische und eiweischemische Befunde bei 6 Patienten mit μ-Kettenkrankheit mitgeteilt. Bei allen Patienten bestand ein lymphoproliferatives Syndrom, das klinisch am ehesten der Chronischen Lymphatischen Leukamie bzw. einem Non-Hodgkin-Lymphom niedrigen Malignitatsgrades entsprach. Die Ahnlichkeit mit der CLL wird durch den Befund einer eingeschrankten Stimulierbarkeit von PBL dieser Falle mit mitogenen Substanzen wie PHA, PWM und Con A unterstrichen. Freie μ-Ketten im Serum sind keiner einheitlichen, klinisch von anderen lymphoproliferativen Erkrankungen abzugrenzenden Symptomatik zuzuordnen und konnen auch im Rahmen einer gutartigen Lymphadenopathie auftreten. In einem Fall konnte durch eine kombinierte Chemotherapie eine uber 4 Jahre andauernde Remission erzielt werden.

Between July 1974 and December 1976 a total of 69 patients were treated for acute nonlymphoblastic leukaemia. The mean age was 42 years. Seven had been previously treated. Induction treatment with daunoblastin and cytarabine was given to 67 patients. It produced complete remission in 37 (55.2%) and partial remission in two. Twelve patients received a minimum of two courses of induction treatment without remission (definite treatment failures). Sixteen patients died during the first 30 days after onset of treatment. Treatment to maintain remission consisted of cytarabine and alternating 6-thioguanine, cyclophosphamide, lomustin and daunoblastin. Treatment could be continued as planned in only a quarter of the patients, because of serious side effects in the others. One year after conclusion of the study (31. 12.77) the median remission period was 42, median survival time for all patients 33 weeks (73.5 weeks for those responding and 8 weeks for those not responding to treatment). Age, fever, and chromosomal status of bone-marrow cells had an effect on prognosis.

Among 334 patients (aged 15-57 years) with malignant non-Hodgkin's lymphoma there were 14 who developed CNS complications, none in 144 with lymphoma of low malignancy. Lymphoblastic lymphoma predominated amoung those with CNS involvement. In adults with this form treatment should therefore be undertaken to prevent such complications. The study confirms the need for histological subclassification in malignant non-Hodgkins's lymphoma.

In two studies, haematopoietic late effects of prolonged bleomycin treatment were evaluated in mice given serial injections of 21 mg bleomycin/m2 weekly for 31 and 44 weeks, respectively. Femoral bone marrow cellularity measured at 43, 45, and 49 weeks after discontinuation of the drug in the first and after 20 weeks in the second study was found to be significantly (P less than 0.05) lower in the treated mice than in the controls. CFU-S, BFU-E, and CFU-C contents were also reduced in the treated bone marrow, but with the exception of CFU-S in the second study, differences from control values were not significant. Additional long-term bone marrow cultures performed in the second study revealed no marked changes in the marrow proliferative activity and the self-renewal of stem cells to explain the reduced marrow cellularity and stem cell content. These last findings might, therefore, be due to a decrease in femoral size with less marrow content in the treated mice, since measurements of the tibial weights in both groups showed that the bones in the treated animals were significantly (P less than 0.05) lighter than those in the controls.

Es wird uber kritische Punkte in der Methodik der CEA-Bestimmung nach Hansen u.a. (CEA-RIA-Test der Firma Hoffmann-La Roche) berichtet. Bei 82 Patienten mit colorectalem Carcinom konnte die CEA-Bestimmung durchgefuhrt werden. Postoperativ wurden bei 43 Patienten 4 Tage, 8 Tage, 14 Tage, 3 Monate und 6 Monate, vereinzelt auch spater, die CEA-Werte beobachtet. Von 61 praoperativ bestimmten Patienten lagen 52,5% uber der vorgeschlagenen Normgrenze von 2,5 ng/ml. Bei der statistischen Auswertung mit der Multivarianzanalyse ergab sich eine Wechselwirkung der verschiedenen Stadien auf die CEA-Werte. Postoperativ fallen die CEA-Werte unterschiedlich rasch ab. Ein Wiederanstieg des CEA-Wertes zeigt bereits weit vor der klinischen Manifestierung das Rezidiv an. In einem Fall wurde pra- und postoperativ trotz Lebermetastasen kein erhohter CEA-Wert gemessen. Erst 11 Monate postoperativ, nach Generalisierung der Erkrankung, konnte ein erhohter CEA-Wert nachgewiesen werden. Es sollte deshalb auch bei normalen CEA-Werten die Verlaufskontrolle fortgesetzt werden.

74 patients with disseminated non-seminomatous testicular cancer were randomly entered on a prospective sequential combination chemotherapy regimen with mandatory crossover, consisting of either vinblastine/bleomycin or adriamycin/cis-dichlorodiammineplatinum (II) (DDP) as initial therapy. Independent of the randomization the overall remission rate in 71 evaluable patients was 89% including 54% complete remissions. 35% of the patients remained disease-free at 2+ to 28+ months with a median of 12 months. By additional surgical removal of residual pulmonary metastases in two patients the complete remission rate was increased to 40/71 (56%), and the number of patients with no evidence of disease to 27/71 (38%). According to the life-table method the two-years survival rates were 63% for complete responders and 29% for all other patients, which was significantly lower. 53 patients (75%) were alive at 3 to 28 months with a median of 9 months. Additional advanced abdominal disease, initially elevated beta-HCG and LDH and extension of pulmonary disease were of significant negative influence on the prognosis. The evaluation of single chemotherapy courses revealed equal efficacy of both combinations. However, response to adriamycin/DDP occurred in 46% of the courses, when vinblastine/bleomycin had failed, while response to vinblastine/bleomycin occurred only in 21% of the courses when adriamycin/DDP had failed. Thus different patterns of cross-resistance between these alternative regimens may exist.

The malignant granular cell tumor ist a rare soft tissue neoplasia which is chiefly localized in the sceletal muscles. The uncertain histogenesis gave rise to different terms. The clinical course is often protracted but fatal. Diagnosis, differential diagnosis, and treatment are discussed in the light of a case report concerning a malignant granular cell tumor in a 28-year-old man.

Combined treatment with three or five chemotherapeutic drugs was given to 115 women with metastasizing breast cancer. These were unselected cases. Three drugs (cyclophosphamide, methotrexate and prednisone) were given to 49 patients, with remissions occurring in 28, arrest in a further five. Five drugs (additional to the three mentioned ones: vincristine and 5-fluorouracil) were given to 66, with remission in 45 and arrest of the disease in another eight. There was no certain difference between the response to the two forms of treatment. Mean survival time for both forms was 13 months in the remission group and six months in the failure group.

The sister chromatid exchange (SCE) frequency in bone-marrow cells of 12 untreated patients with chronic myelocytic leukemia (CML) was analysed and compared with the SCE frequency in bone-marrow cells of nine healthy persons. In normal persons the SCE ranged from 3.64 to 5.15 per cell. In CML patients the SCE was significantly lower, ranging from 2.32 to 3.44 per cell. The differences found were unrelated to patients' age and contraction state of the chromosomes. It is suggested that the leukemic process could account for the low SCE rate.

Exploratory laparotomy with splenectomy was performed on 275 patients with hisologically confirmed Hodgkin's disease. In 188 patients the laparotomy was a primary one to determine more precisely the state of the disease. A secondary laparotomy was performed in 87 patients 1-12 years after diagnosis and radiotherapy. In 17.5% of patients the state had to be revised after laparotomy with splenectomy. In 38 the disease had further progressed, while in ten it had slighty regressed. In four cases clinical stage I proved to be stage III. Even prognostically more favourable forms may have progressed at first diagnosis. There was no correlation between B-symptoms and histological type, but there was between B-symptoms and spread of the disease. Calculated spleen weight provided no clue as to spleen involvement. There was no clear relationship between spleen involvement and histological subclassification. Risk-effect analysis indicate that laparotomy with splenectomy was useful because it makes optimal treatment possible.

Fifty patients with inoperable bronchial carcinoma were treated with a combined schedule of adriamycin, cyclophosphamide and vincristine. In those cases with locally/regionally confined tumour spread this was followed - after three chemotherapy cycles - by radiotherapy to mediastinum, hilar region and tumour of 3000 rad focal dose. Remission was achieved in 25 of 27 patients with small-cell carcinoma: full clinical remission in 12, part remission in 13. Mean duration of the (in most instances still continuing) remission has so far been 4 + months. Mean survival time is, of course, not yet calculable. Only a few patients had to be admitted to hospital for short periods because of toxic reactions. Four full and 11 part remission (some still continuing) have so far been achieved in the group of larger-cell carcinoma (squamous cell, 4; large cells, 5; anaplastic, medium-large, undifferentiated or polymorph, 14).

6 Patienten mit einer Haarzellenleukamie wurden 3–35 Monate nach Splenektomie mit IFN-γ (4 × 106 E/m2/2. Tag sc) behandelt. Wahrend einer Therapiedauer von 9–35 Wochen konnte bei keinem Patienten eine signifikante klinische oder hamatologische Befundbesserung erzielt werden. Nach einem therapiefreien Intervall von 0–13 Wochen erhielten alle Patienten IFN-α-2b (zunachst 4 × 106 E/m2/2. Tag, Erhaltungstherapie 1 × 106 E/2. Tag). Zum Zeitpunkt der Beendigung der jeweiligen IFN-α-2b-Gabe war bei 5 von 6 Patienten (1 Patient mit postthrombotischem Syndrom verstarb an einer Lungenembolie) eine deutliche Befundbesserung eingetreten. Nach einer Beobachtungszeit von jetzt 9–14 Monaten konnten 1 CR, 3 PR und 1 MR induziert werden. Die Nebenwirkungen beider Interferon-Praparationen unterschieden sich nicht signifikant.

Seit Juli 1978 wurden 103 Patienten mit inoperablem kleinzelligem Bronchialkarzinom mit der Zytostatikakombination Adriamycin, Cyclophosphamid und Vincristin (ACO) behandelt. Im Stadium „limited disease“ (n=64) erfolgte wahrend des zweiten Chemotherapiekurses eine prophylaktische Schadelbestrahlung, nach dem vierten eine konsolidierende thorakale Bestrahlung. Nach Erreichen einer kompletten Remission erhielten die Patienten prospektiv randomisiert Etoposid oder keine weitere spezifische Therapie. Ein objektives Ansprechen konnte bei 88/100 auswertbaren Patienten erzielt werden. Im Stadium „limited disease“ fanden sich 72%, im Stadium „extensive disease“ nur 33% komplette Remissionen. Im Stadium „limited disease“ betrug die hochgerechnete mediane Uberlebenszeit 15,8, im Stadium „extensive disease“ 9,3 Monate (p

Clinical reports concerning the therapeutic effects of high dose Cytosine arabinoside (HD Ara-C) in meningeal leukemia are relatively rare. Pharmacokinetic studies, however, have indicated potentially effective concentrations of Ara-C in cerebrospinal fluid (CSF) during and after high-dose infusions of the drug given intravenously. In this report, the treatment results of HD Ara-C in 14 patients with refractory or relapsed acute leukemia are presented including those of 2 patients with meningeal leukemia. In these 2 patients as well as in 1 patient without central nervous system (CNS) leukemia, Ara-C and Ara-U concentrations in CSF and plasma were measured during a 6-day therapy with HD Ara-C (3 g/m2 q 12h 12 X). Ara-C and Ara-U levels were determined on Days 3 and 6 of therapy, each at the end of a 3-h i.v. infusion of the drug. In the 14 patients (8 with AML, 6 with ALL) treated, a total number of 17 treatment cycles were given for remission induction with doses of Ara-C ranging from 1-3 g/m2 q 12 h 6-12 X. A complete remission rate of 47% was achieved. The duration of remission ranged from 1 to 6 months. Of the 2 patients with CNS leukemia, 1 patient achieved complete remission both in CSF and in bone marrow, the other patient only in CSF. The mean concentration of Ara-C in CSF was 903 ng/ml with a ratio of 0.38 to that in plasma. Ara-C and Ara-U did not appear to accumulate in CSF or in plasma.(ABSTRACT TRUNCATED AT 250 WORDS)

Knochenmarksproben von Patienten mit Teratokarzinom unter zytostatischer Langzeitchemotherapie wurden mit der Agarkultur (CFU-C) und in der Diffusionskammer (DK) untersucht. Wahrend einer zwolfmonatigen Beobachtungsperiode zeigte sich keine signifikante Abnahme der CFU-C-Zahl oder der DK-Proliferationskapazitat. Im Unterschied hierzu wurde bei Patienten mit akuter Leukamie in Vollremission ein signifikanter Abfall der CFU-C im Knochenmark im Verhaltnis zur Dauer der Remission und der zytostatischen Behandlung gefunden.

Twenty-one patients with chronic granulocytic leukaemia underwent marrow transplantation. The donors were human-lymphocyte antigen-identical siblings in 19 cases. In the remaining 2 cases the donor was a parent in one and an identical twin in the other. The preparatory regimen included cyclophosphamide and 8.6 Gy total body irradiation given at either a dose of 0.1 Gy/min or 0.04 Gy/min. Five patients were in the accelerated phase of the disease, one was in remission following blast crisis, and the rest were all in the chronic phase. After chemotherapy and irradiation, all patients received bone marrow transplants. To date, nine patients are still alive, with a median survival of 64 days (range 28-683 days). One patient continued to have leukaemic cells and in another, the leukaemia recurred 18 months following transplantation. Interstitial pneumonitis was the cause of death of eight patients (38%). Graft-versus-host disease occurred in ten patients (47%).

62, chemotherapeutisch nicht vorbehandelte Patienten mit metastasierten Weichteilsarkomen wurden mit dem Cyvadic-Schema behandelt. Komplette Remissionen wurden bei 10 %, komplette plus partielle Remissionen bei 20 % der Patienten erreicht. Die mittlere Dauer der kompletten Remission betrug 25, der partiellen Remission 2,5 Monate. Die mittlere Uberlebenszeit der Patienten, die auf die Therapie ansprachen, lag bei 28 Monaten, bei den nicht-ansprechenden Patienten bei 14 Monaten. Die Chemotherapie mit Ifosfamid plus Cisplatin fuhrte bei 50 % der Patienten mit primarer oder sekundarer Cyvadic-Resistenz zu Remissionen.

The value of sequential alternating chemotherapy was analyzed retrospectively in 180 patients with disseminated, non-seminomatous testicular cancer. Response rates of adriamycin/cisplatin--(combination A) and bleomycin/vinblastine (combination B)--combination chemotherapy were evaluated separately with respect to tumor histology and tumor stages. Tumor response was achieved in 151 of 180 patients (84%) who were evaluable for adriamycin/cisplatin chemotherapy. Out of those, 91 of 117 patients (78%) pretreated with combination B and 60 of 63 patients (95%) without prior chemotherapy responded. Irrespective of pretreatment tumor response was observed in 131 of 157 patients (84%) evaluable for treatment with bleomycin/vinblastine. Resistance to combination A was 2.5 fold higher in embryonal carcinomas (class II of Dixon and Moore) than in choriocarcinomas (class V). Bleomycin/vinblastine-therapy failed more frequently in choriocarcinomas as compared to other histological categories (22% vs. 14%). This report also includes an analysis of treatment failures in different tumor stages. Both regimens were more frequently ineffective in tumor stages with a large tumor burden (stages II C and IV D). Patterns of cross-resistance were evaluated for both regimens. Response to adriamycin/cisplatin occurred in 18/26 patients (69%), when combination B had failed, and response to bleomycin/vinblastine was achieved in 14/24 patients (58%) when adriamycin/cisplatin had failed. In patients not responding to either regimen the treatment failure was already recognized after the first chemotherapeutic course in 93% of these cases.

The evolution of medical oncology so far owes much to the preclinical and clinical development of antineoplastic agents. Prognostic factors and empiric treatment strategies have guided the clinician in his choice of drugs. In the light of increasing ethical restrictions met with phase I-II clinical trials and major advances in propagating human tumor cells outside the donor patient, a reappraisal of predictive tests in cancer chemotherapy is warranted. Among 'short-term assays' only the determination of steroid-hormone receptor content in tumor tissues has gained clinical acceptance, whereas other methods still suffer from theoretical or practical shortcomings. Both the human tumor stem cell assay and the xenograft model have revealed unique patterns of sensitivity for each individual tumor line. While interindividual heterogeneity among tumors sharing a common site of origin justifies efforts to develop predictive tests, microheterogeneity among tumor samples from the same donor patient limits the potential of this approach. Predictive tests should be performed in conjunction with clinical trials to ensure optimal extraction of information. As additional prognostic factors, they should in the near future accelerate drug development and reduce the hazard of unnecessary drug toxicity without therapeutic benefit.

Chemotherapy of malignant melanoma is indicated in advanced disease when local treatment is no longer possible. The results of single-agent chemotherapy, including alkylating agents, antimetabolites and several antibiotics as well as vinca alkaloids and recently the nitrosoureas, are critically reviewed. The overall response rates do not reach levels about 15 percent. The imidazole carboxamide compound (DTIC) has been most extensively studied, And increases the response rate to about 25 percent. The influence of pretreatment and the preponderance of certain localizations, and also the survival rates of responders, partial responders and nonresponders are discussed. Combination chemotherapy seems not to be superior to single-agent therapy. Various factors, including biochemical, pharmacological, cytokinetic and immunologic parameters that differentiate responders from nonresponders, still require examination.

75 cases treated between 1970 and 1976 for malignant follicular non-Hodgkin's lymphoma were analysed for their cardinal signs. Contrary to non-Hodgkin's lymphoma of "higher malignancy degree", the average age of patients with malignant follicular non-Hodgkin's lymphoma is generally over 50 years, being more common in females. By the time the diagnosis is made a generalised stage has usually been reached. In the described group of patients the five-year survival rate was 65%, but compared with the malignant lymphoma of higher malignancy the prognosis is often complicated by secondary diseases resulting from the higher age. The findings confirm the need for histological sub-classification of malignant non-Hodgkin's lymphoma.

Yoshida-Ascitestumorzellen wurden elektronenmikroskopisch untersucht. In unbehandeltem Zustand ergab sich eine gute Ausdifferenzierung der uberwiegenden Anzahl der Tumorzellen.

In 10 Fallen von Arteriosklerose und Endangitis obliterans wurde unmittelbar nach der Amputation der unteren Gliedmasen der Glykogengehalt der Oberschenkel-, der Unterschenkel- und der Plantarmuskulatur untersucht. Im Gegensatz zu dem schweren klinischen Erscheinungsbild mit Nekrosenbildung der distalen Extremitatenanteile war die Glykogenkonzentration in der untersuchten Muskulatur durchweg unverandert. Erst bei Ubergreifen der Nekrosen auf die Muskulatur konnte in dieser ein starker Glykogenschwund nachgewiesen werden. Die Ergebnisse werden im Hinblick auf die engen Beziehungen zwischen Glykogensynthese und Sauerstoffversorgung — insbesondere der schnellen Glykogenolyse bei O2-Mangel — als indirekter Hinweis auf die Existenz eines relativ guten Kollateralkreislaufs aufgefast. Nekrosenbildung der distalen Anteile der unteren Extremitaten gestattet noch keine Aussage uber die Durchblutung der benachbarten Gewebsanteile.

Wir berichten uber den ersten uns bekannten Fall eines serologisch gesicherten Burkitt-Lymphoms in Deutschland. Die Histologie ergab das typische Bild eines „Sternenhimmels“. Das Serum des Patienten enthielt pracipitierende Antikorper gegen das aus Burkitt-Gewebe-Kulturzellen gewonnene Antigen. Der Antikorpertiter im indirekten Fluorescenztest war 1:640. Stoffwechseluntersuchung der Zellen ergab eine signifikante Glutaminmangelempfindlichkeit ohne gleichzeitige Asparaginabhangigkeit. Die klinischen Befunde, das typische histologische Bild und das initial eindrucksvolle Ansprechen auf die Chemotherapie zusammen mit dem hohen Antikorpertiter gegen das Epstein-Barr-Virus lassen die Diagnose Burkitt-Lymphom gesichert erscheinen. Epidemiologie, Klinik, Histologie und Immunologie werden im Lichte der heute bekannten Tatsachen uber das Burkitt-Lymphom diskutiert.

Rauchtabak wurden die mehrwertigen Alkohole 1,3-Butandiol oder Glycerin als Feuchthaltemittel zugesetzt, die — zumindest zum Teil — unverandert in den Rauch ubergehen. Da es sich bei der Aufnahme der beiden Substanzen mit dem Tabakrauch durch die Schleimhaute und die Epithelien des Atmungstraktes um einen anders gearteten Resorptionsvorgang handelt als bei oraler Applikation, muste untersucht werden, ob 1,3-Butandiol und Glycerin — bzw. ihre moglicherweise entstehenden Verbrennungsprodukte — hier ebenso unschadlich sind, wie bei innerlicher Anwendung.

Idiopathic thrombocytopenic purpura (ITP) in the course of Hodgkin's disease is generally judged to be a paraneoplastic immune phenomenon. This concept finds support in the observation of a patient who developed simultaneously a recurrence of ITP and a protein anomaly in the form of an alpha-chain protein. Combined chemotherapy brought about remission of the Hodgkin's disease at the same time as normalisation of the platelet values and disappearance of the alpha-chain protein. There is no necessary correlation between tumour activity and ITP. But if ITP is observed, the most effective means would seem to be rigorous treatment of the Hodgkin's disease.

Im Rahmen einer kombinierten Phase-I/II-Studie erhielten 2 Patien-ten nach allogener Knochenmarktransplantation (BMT) wegen einer akuten Graft-versus-Host-Reaktion (GvHD) des klinischen Schwere-grades

Between January, 1977, and September, 1978, 14 stage III and 7 stage IV patients with previously untreated non-Hodgkin's lymphoma were selected for low-dose fractionated total body irradiation (TBI), 150 rad in 10 fractions over 5 weeks, combined with cyclophosphamide, vincristine, and prednisone (COP) cytostatic therapy. A randomized trial was established to compare the treatment related toxicity of TBI plus COP (group A) or COP plus TBI (group B), and the efficacy to increase the response rate, particularly the complete remission rate. Fifteen patients were treated with TBI plus COP and 6 patients received COP plus TBI. The latter part of each treatment modality was delayed 6 weeks to allow recovery from the myelosuppressive effects of the foregoing one. Complete remission was achieved in 8/15 group A patients and in 3/6 treated according the group B schedule. There were no acute symptoms during either course nor could mortality associated with the treatment be observed.

It is now well established that chemotherapy can exert a significant degree of palliation in women with advanced breast cancer lesions. Secondary drug therapy is ultimately required in most women with disseminated breast cancer. Alkylating agents, antimetabolites, vinca alkaloids, cytostatic antibiotics and miscellaneous agents have been used either as single drugs or in more modern combination regimes.

SummaryTwenty-two previously treated patients with recurrent or primarily resistant small cell bronchogenic carcinoma were treated every 3 weeks with a combination of vindesine (3–4 mg/m2 i. v.) and cisplatin (60–100 mg/m2 as 6-h infusion) until progression. One patient achieved a complete remission, three a partial remission and eight patients minor responses (overall response rate 55 %). Survival time lasted from 3 to 30 weeks (median: 12). There were no drug-related deaths, toxicity was in most cases limited to gastrointestinal and hematological side effects.

A 20-yr-old man with bulky mediastinal and retroperitoneal tumour masses identified as myeloblastoma is described. After a partial remission was induced by aggressive chemotherapy, mediastinal irradiation and retroperitoneal tumour resection, the patient received an allogeneic marrow graft from his HLA-identical sister. The conditioning regimen consisted of high-dose busulfan and cyclophosphamide. The patient has a well-controlled secondary chronic graft-versus-host disease. He is in unmaintained complete remission and in good general condition at 20 months post-transplantation.

Aggressive chemotherapy of acute lymphoblastic leukemia (ALL) in childhood has led to long-term survival and potential cure in more than 50% of the patients. Despite recent advances in the treatment of adult acute leukemia, the majority of these patients die due to recurrence of the disease within 2 years of diagnosis.

Acute effects of ASTA Z 7557 and Cyclophosphamide (Cy) on pluripotential (CFU-S), granulocytic (CFU-C), early erythroid (BFU-E) and late erythroid (CFU-E) progenitor cells in the bone marrow, as well as on RBC and WBC, were compared in F1 (CBA × C 57 BL) female mice. Dose-survival curves of both agents for CFU-S and CFU-C were found to be exponential, indicating that the effects of the drugs have no cell cycle dependency. At equimolar doses, marrow CFU-S and CFU-C contents appeared to decrease more rapidly with increasing doses of ASTA Z 7557 than with those of Cy. After a single dose of 200 mg/kg of each drug (= 50% LD10), there was greater initial suppression of CFU-S, CFU-C, BFU-E and CFU-E in the Cy-treated animals than in ASTA Z 7557-treated mice. In both groups, however, the WBC had their nadir on Day 3 after treatment, followed by a return to normal by Day 8. In ASTA Z 7557-treated animals, the recovery of CFU-S, CFU-C and BFU-E was also completed by Day 8 after treatment. In Cy-treated mice, however, complete recovery of these cells was achieved on Day 15. Results indicate quantitative rather than qualitative differences between the marrow toxicities of ASTA Z 7557 and Cy in mice. Quantitative differences could be due to different pharmacokinetic properties of the agents, since Cy is excreted in partially unmetabolized form, and it might be that this inactive part of the agent grew with increasing drug doses.