Autologous bone marrow transplantation: present status and future prospects

Cytokine intervention permits dose escalation of radioantibody. An analysis of myelostimulation by bolus versus continuous infusion of IL-1/GM-CSF

BACKGROUND

The authors recently reported that a 12-day schedule (beginning 3 days before radioantibody treatment) of twice-daily dosing of rH-IL-1 (1 x 10(3) U/dose) and rM-GM-CSF (0.5 micrograms/dose) can reduce the magnitude and duration of radioantibody-induced myelosuppression, thereby permitting a 25-30% increase in the dose of radioantibody that can be administered without the dose proving lethal. In an effort to further reduce toxicity and escalate the tolerated dose, the authors altered the method of administration of cytokines from daily bolus dosing to continuous infusion by implantable osmotic pumps.

METHODS

A control group of mice was compared to five groups of mice that either did or did not receive a 340 microCi dose of radioantibody, and received no cytokines, cytokines by bolus dosing, or cytokines by continuous infusion. For 4 weeks, peripheral white blood cell and thrombocyte counts and thymus and spleen weights were taken, marrow cell number was monitored, and marrow colony-forming unit activity was evaluated weekly in the untreated control mice and the treated mice.

RESULTS

These studies demonstrated that after a dose of radioantibody, continuous dosing of cytokines resulted in higher white blood cell (WBC) and platelet values than if bolus delivery was used (day 7, WBC: 110% vs. 59%; day 14, WBC: 85% vs. 62%; day 21, WBC: 98% vs. 42%; day 7, platelets: 122% vs. 51%; day 14, platelets: 159% vs. 72%; day 21, platelets: 239% vs. 171%). A comparison of bolus versus continuous dosing in the absence of radioantibody indicated that spleen weight increased by 40-60% after continuous infusion of cytokines and by 20-25% after bolus dosing. The 20-30% decrease in thymus weight was similar with both dosing regimens. Colony-forming units (CFUs) in marrow increased from 30-35 in untreated mice to 50-55 in mice given cytokines by bolus injection, and to 150-180 in mice given continuous infusion of cytokines. Spleen CFUs exhibited an insignificant increase after bolus dosing of cytokines but increased almost fourfold after continuous dosing. Peak stimulation of marrow and spleen CFUs occurred 28 days after initiation of cytokine administration (2 weeks after cytokines administration was stopped). The probability of survival for 6 weeks after further dose escalation to 360 microCi I-131-MN-14 immunoglobulin G was 16.4% +/- 8.6% after bolus dosing and 58.1% +/- 11.3% after continuous infusion of cytokines.

CONCLUSIONS

Although continuous infusion of cytokines proved to be a better method of reducing hematopoietic toxicity, further dose escalation of radioimmunotherapy using the "pump" method of cytokine delivery was not possible. Cytokine intervention by either mode of delivery permits a 25% dose intensification without the dose becoming lethal. Further escalation is not feasible, possibly because of other end organ toxicity.

High-dose chemotherapy with busulphan and cyclophosphamide and bone-marrow transplantation for drug-sensitive malignancies in adults: a preliminary report

The technique of high-dose chemotherapy and bone-marrow transplantation takes advantage of any potential dose-response effect in the treatment of cancer and the ability of infused marrow to circumvent severe myelotoxicity. We report our initial experience of 20 high-dose chemotherapy procedures with busulphan and cyclophosphamide as the treatment regimen. Autologous (14 patients), human leukocyte antigen-matched, sibling-allogeneic (five patients) and identical-twin (one patient) transplantations were performed in patients with leukaemias (12 patients), lymphomas (seven patients) or a germ-cell tumour (one patient). One in-hospital and one late death occurred as a result of the toxicity of high-dose chemotherapy. All evaluable patients demonstrated bone-marrow engraftment and became independent of blood transfusions. Five of six patients who were treated in partial remission or relapse obtained a complete remission. Seven patients have relapsed. Eleven patients currently are alive and disease-free and nine patients have returned to their full-time occupations. High-dose chemotherapy can be undertaken with an over-all morbidity that is similar to that which is experienced during the induction chemotherapy of acute leukaemia.

Effect of granulocyte colony stimulating factor on neutropenia induced by cytotoxic chemotherapy

A phase I/II study of granulocyte colony stimulating factor (G-CSF) was undertaken in patients with advanced malignancy receiving melphalan to determine the granulocyte response, side-effects, and pharmacokinetics. Patients received doses of 1-60 micrograms/kg intravenously. There were 3 patients at each dose level. Before chemotherapy the immediate effect of G-CSF was a transient depression in circulating neutrophils followed by a dose-dependent rise. Neutrophil counts up to 80 X 10(9)/l were achieved. G-CSF administration following melphalan reduced the period of neutropenia caused by melphalan. G-CSF was well tolerated and the only clinical observation that appeared related to G-CSF administration was slight bone pain during some infusions. G-CSF was rapidly cleared from the blood with a mean half-life of 110 min for the second phase. Reductions in the number of days of neutropenia following cytotoxic chemotherapy may reduce the morbidity and mortality of chemotherapy.