Effect of G-CSF and M-CSF on the in vitro Toxicity Associated with Zidovudine in Normal Human Bone Marrow Haematopoietic Progenitor Stem Cells

Zidovudine, the antiviral drug used in the treatment of acquired immunodeficiency syndrome (AIDS), causes toxicity to the haematopoietic system. Although use of the haematopoietic growth factors, GM-CSF and erythropoietin have been investigated in clinical trials to modulate antiviral toxicity, there is scant data which supports their ability to ameliorate zidovudine induced toxicity on haematopoietic progenitor cells when combined in vitro. We describe here the results of studies designed to evaluate the capacity of additional haematopoietic factors such as granulocyte-colony stimulating factor (G-CSF) and macrophage-colony stimulating factor (M-CSF) to modulate zidovudine-induced toxicity on G-CSF and M-CSF dependent-colony formation in the presence or absence of zidovudine in vitro. These factors were also studied combined with erythropoietin in culture for the early erythroid progenitor BFU-E using adherent, T-cell, depleted normal human bone marrow cells in the presence or absence of zidovudine. In the presence of zidovudine at the concentration producing 50% inhibition of G- and M-CSF dependent colony formation, (5 × 10−5M), dose-escalation of either G-CSF or M-CSF failed to ameliorate zidovudine toxicity. However, in the presence of zidovudine at the concentration that produces 50% inhibition of BFU-E (5 × 10−9M), and optimal erythropoietin (1 unit ml−1), G-CSF ameliorated zidovudine inhibition of BFU-E, which was not observed with M-CSF. In the presence of erythropoietin, G-CSF increased significantly normal BFU-E. These studies indicate that G-CSF may be useful in ameliorating zidovudine-induced anaemia and suggest G-CSF may act as a synergistic factor to enhance erythropoietin to support the growth of erythroid progenitors in conditions where erythropoitin is ineffective.

Influence of human granulocyte-macrophage colony stimulating factor/interleukin-3 fusion protein (PIXY321) on the hematopoietic toxicity associated with anti-viral drugs (zidovudine and didanosine) in vitro using normal human marrow cells

The antiviral drugs didanosine (ddI) and zidovudine (AZT), synthetic nucleoside analogs, have been used in the treatment of acquired immunodeficiency syndrome (AIDS). Although clinical use of zidovudine (AZT) is still widely used, it is associated with the development of virus disease resistance and toxicity to the hematopoietic system. Alternative nucleoside reverse transcriptase derivatives such as didanosine (ddI) have been developed in order to reduce the incidence of virus disease resistance and hematological toxicity. We report here studies designed to ev evaluate the toxicity profile comparing didanosine (ddI) with zidovudine (AZT) when used alone or in combination with normal non-adherent, T-cell depleted human marrow cells plated in the presence or absence of the human cytokine fusion protein of granulocyte-macrophage colony stimulating factor and interleukin-3 (PIXY321). As expected, didanosine (ddI) was less toxic for human hematopoietic progenitor cells, i.e., CFU-GEMM, CFU-GM, CFU-Meg, and BFU-E than zidovudine. Toxicity was additive when didanosine (ddI) and zidovudine (AZT) were combined. In the absence of drugs PIXY321 colony formation was increased for all progenitor cells cultured. In the presence of didanosine (ddI) or zidovudine (AZT), either as single-agents or combined, PIXY321 reduced toxicity significantly. These results demonstrate PIXY321 is an effective cytokine capable of reversing the toxicity associated with anti-viral drugs when used in vitro where didanosine (ddI) is less toxic than zidovudine (AZT); however their suppression of hematopoietic progenitors is additive when combined.

Influence of interleukin-3 (IL-3) on the hematopoietic toxicity associated with combination anti-viral drugs (zidovudine and DDI) in vitro using retrovirus-infected bone marrow cells

The drug zidovudine (AZT), a synthetic thymidine analog, has been used in the treatment of acquired immunodeficiency syndrome (AIDS). Clinical use of zidovudine has been associated with the development of hematopoietic toxicity manifested by anemia, neutropenia, and on occasion thrombocytopenia. This toxicity has resulted in the development of alternative dideoxynucleoside drugs capable of exerting anti-viral potency while minimizing the risk for inducing organ toxicities. One such dideoxynucleoside drug is 2',3'-dideoxyinosine (ddI). Clinical trials are currently evaluating the effect of combination anti-viral drug treatment such as zidovudine plus ddI. We report here the results of studies designed to evaluate the effect of interleukin-3 (IL-3) on its ability to influence the hematopoietic toxicity associated with zidovudine and ddI following combination with retroviral-infected murine bone marrow cells. Toxicity was evaluated by quantitating several classes of hematopoietic progenitor stem cells such as granulocyte-macrophage (CFU-GM), erythroid (CFU-E and BFU-E) and megakaryocyte (CFU-Meg). Dose-escalation IL-3 provided protection of anti-viral drug induced suppression of progenitor cells when combined in the presence of the ID50 concentration of either zidovudine or ddI; however, when zidovudine and ddI were combined, IL-3 was less effective in providing protection against drug-induced toxicity at any concentration examined. These results indicate that IL-3 is effective in reducing anti-viral drug-induced hematopoietic toxicity associated with single-agent use; however, IL-3 is less effective when such drugs are used in combination.

Comparison of dideoxynucleoside drugs (DDI and zidovudine) and induction of hematopoietic toxicity using normal human bone marrow cells in vitro

The drug zidovudine (AZT), a synthetic thymidine analog, has been used in the treatment of acquired immunodeficiency syndrome (AIDS). Clinical use of zidovudine has induced hematopoietic toxicity manifested by anemia, neutropenia and on occasion thrombocytopenia. Such toxicity has stimulated the development of alternative dideoxynucleoside drugs capable of exerting anti-viral potency while minimizing the risk for inducing organ toxicities. One such alternative dideoxynucleoside drug is 2',3'-dideoxyinosine (ddI). Recent therapeutic anti-viral strategy, now undergoing clinical trial, is the evaluation of combined zidovudine ddI treatment. Unfortunately a complete assessment of their potential toxicity using this drug regimen has not been thoroughly examined. We report here the results of studies comparing the toxicity profile of zidovudine versus ddI on their ability to influence several classes of hematopoietic progenitor stem cells, e.g. granulocyte--macrophage (CFU-GM), megakaryocyte (CFU-Meg) and erythroid (CFU-E/BFU-E) following in vitro co-culture with normal human bone marrow. Since the main clinical toxicity associated with zidovudine in vivo is the development of anemia, additional in vitro studies compared the dose-escalation effect of erythropoietin in the presence of combined zidovudine and ddI. CFU-GM, CFU-Meg, CFU-E and BFU-E were all reduced (P < 0.05) following incubation with either zidovudine or ddI thus determining their ID50 concentrations for these classes of hematopoietic progenitors; however, the extent of toxicity associated with ddI was lower than what was observed with zidovudine. More importantly, dose-escalation of erythropoietin was effective in reversing the inhibition observed for ddI on erythroid progenitors CFU-E and BFU-E (P < 0.05), an effect not reported with zidovudine in vitro.(ABSTRACT TRUNCATED AT 250 WORDS)

In-vivo effect of interleukin 3 and erythropoietin, either alone or in combination, on the hematopoietic toxicity associated with zidovudine

We studied the effect of erythropoietin (EPO) and interleukin 3 (IL-3), either alone or in combination, on the hematopoietic toxicity associated with zidovudine in vivo, as determined by peripheral blood indices, and assay of hematopoietic progenitors, i.e. erythroid (CFU-E/BFU-E), myeloid (CFU-GM) and megakaryocyte (CFU-Meg) from bone marrow and spleen. Previous studies from this laboratory have established that dose escalation of zidovudine to normal mice induced a dose-dependent decrease in hematocrit, white blood cells and platelets with altered populations of marrow and splenic erythroid, myeloid and megakaryocyte progenitors. Daily administration of EPO (50 U/animal, i.p.) and/or IL-3 (5 U/animal, i.p.) was associated with altered peripheral blood indices and progenitor cells. In general, use of EPO and IL-3 alone reduced zidovudine-induced toxicity, notably in erythropoiesis; however, combination EPO/IL-3 was associated with enhanced toxicity with an observed rebound only with the use of < 2.5 mg/ml drug; 2.5 mg/ml drug in the presence of combination EPO/IL-3 accelerated zidovudine-erythroid toxicity. A similar response was noted with circulating platelets and megakaryocyte progenitors. Use of EPO or IL-3, either alone or in combination, failed to reverse zidovudine-induced neutropenia. These studies demonstrate that use of EPO or IL-3, either alone or in combination may serve as an effective adjuvant therapy to modulate the erythroid toxicity associated with lower doses of zidovudine; however, this cytokine therapy was ineffective modulating zidovudine-induced myelosuppression when used in vivo. A reversal in zidovudine-induced myeloid toxicity, therefore may require the use of a myelopoiesis inducing cytokine.