Cell kinetics of CD34-positive hematopoietic cells following chemotherapy plus colony-stimulating factors in advanced breast cancer

Cytokinetic-driven myeloprotection after cytotoxic chemotherapy: from an old idea to a new clinical approach

Chemotherapy is the backbone of the treatment of several solid tumours and lymphomas. Myelotoxicity is often a dose-limiting toxicity and myeloprotection has always been investigated. In fact, over the years, several approaches have been studied in order to reduce the incidence of haematological toxicities and allow patients to receive effective, full-dose, chemotherapy. After the use of stimulating factors, such as granulocyte colony-stimulating factors and erythropoiesis-stimulating agents, in the very last years, a new approach has emerged. Trilaciclib, a cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitor, has been studied and it has been demonstrated in several clinical trials to reduce the incidence of myelotoxicity in small-cell lung cancer patients treated with chemotherapy or chemo-immunotherapy. Its potential role has not been fully studied yet, but it represents a highly effective tool to reduce myelotoxicity, widen the applicability of full-dose chemotherapy, even in frailer patients, and finally to increase the efficacy of chemotherapy in those tumours where relative dose intensity is a standard to achieve to get the best clinical results.

Fluorochromes for DNA Staining and Quantitation

In these last few decades the great explosion of the molecular approaches has casted a little shadow on the DNA quantitative analysis. Nevertheless DNA cytochemistry represented a long piece of history in cell biology since the advent of the Feulgen reaction. This discovery was really the milestone of the emerging quantitative cytochemistry, and scientists from all over the world produced a very large literature on this subject. This first era of quantitation (histochemistry followed by cytochemistry) started by means of absorption measurements (histophotometry and cytophotometry). The successive introduction of fluorescence microscopy gave a great boost to quantitation, making easier and faster the determination of cell components by means of cytofluorometry. The development of flow cytometry further contributed to the importance of quantitative cytochemistry. At its beginning, the mission of flow cytometry was still DNA quantitation. For a decade the Feulgen reaction had been the reference methodology for both conventional and flow cytofluorometry; the advent of Shiff-type reagents contributed to expand the variety of possible fluorochromes excitable in the entire visible spectrum as well as in the ultraviolet region. The fluorescence scenario was progressively enriched by new probes among which are the intercalating dyes which made DNA quantitation simple and fast, thus spreading it worldwide. The final explosion of cytofluorometry was made possible by the availability of a large variety of probes directly binding DNA structure. In addition, immunofluorescence allowed to correlate the cell cycle-related DNA content to other cell markers. In the clinical application of flow cytometry, this promoted the introduction of multiparametric analyses aimed at describing the cytokinetic characteristics of a given cell subpopulation defined by a specific immunophenotype setting.

Timely Withdrawal of G-CSF Reduces the Occurrence of Thrombocytopenia During Dose-dense Chemotherapy

BACKGROUND

Post chemotherapy Granulocyte colony stimulating factor (G-CSF) reduces leucopenia, while G-CSF priming shortly before chemotherapy increases myelotoxicity. We performed a trial with a two-schedule crossover design to determine the optimal G-CSF schedule for densified 2-weekly chemotherapy.

METHODS

During 2-weekly chemotherapy days 1 and 2, G-CSF was given on days 3-10, with a G-CSF-free interval before the next chemotherapy cycle of 5 days, or on days 3-13, with a G-CSF-free interval of 2 days. In schedule A, cycle II was preceded by a 5 days, cycle III and IV by a 2 days and cycle V by a 5 days G-CSF free interval. In schedule B, this was 2, 5, 5, and 2 days, respectively.

RESULTS

Intra-patient comparison for cycles II versus III and cycles IV versus V showed that platelet (PLT) nadir count was significantly lower for cycles preceded by a 2-days compared to a 5-days G-CSF free interval: mean difference 45.7 x 10(9)/l (95% CI 33.2-58.2, p = 0.0001). Neutrophil count did not differ significantly (p = 0.85).

CONCLUSION

Timely withdrawal of G-CSF in dose-dense chemotherapy reduces chemotherapy-related thrombocytopenia. Leucopenia was not aggravated, reflecting a protective effect of post-chemotherapy G-CSF.

Impaired bone marrow hematopoietic progenitor cell function in rheumatoid arthritis patients candidated to autologous hematopoietic stem cell transplantation

We have evaluated bone marrow morphology, percentage of bone marrow CD34(+) cells, proliferative activity of bone marrow precursors, clonogenic assay (BFU-E and CFU-GM) in short-term bone marrow cultures, and bone marrow cell apoptosis, together with serum TNF-alpha and IL-6, in 16 chronic, refractory RA patients, as well as in five healthy controls. Of 16 RA patients (68.7%), 11 showed a reduced bone marrow cellularity, while it was normal in all the controls. In RA patients, the median percentage of CD34(+) bone marrow cells, the median percentage of proliferating bone marrow myeloid precursors, and the median number of both BFU-E and CFU-GM colonies were significantly lower than observed in the controls. As far as TNF-alpha and IL-6 titers is concerned, the latter did not significantly differ from controls' values, while TNF-alpha titers were significantly lower in healthy controls. Finally, the median apoptotic index of early bone marrow myeloid cells of RA patients was significantly higher compared with controls. These observations may identify the biological risk factors for impaired mobilization and/or engraftment when RA patients are candidates for autologous hematopoietic stem cell grafting.

Myeloprotective Effect of Early Primary Granulocyte-Colony Stimulating Factor during Six Courses of Intensified 5-Fluorouracil, Epirubicin and Cyclophosphamide (120FEC) Chemotherapy for Advanced Breast Cancer

Aims and background

The neutropenia induced by six courses of an intensified FEC regimen is expected to be checked by early primary administration of G-CSF which is stopped eight days before the next chemotherapy course. Less information is available about megakaryocytic and erythroid toxicity over six courses.

Methods and study design

Sixty-six consecutive patients with metastatic breast cancer completed six courses of a randomized treatment with two FEC regimens adminstered every 21 days, in which 600 mg/m2 of cyclophosphamide and 5-FU was associated with 60 or 120 mg/m2 of epirubicin (60FEC, 35 patients, vs 120FEC, 31 patients). 120FEC was supported by early primary G-CSF (days 4 to 13). Blood counts were obtained seven times during each course.

Results

The non-hematologic toxicity over 364 courses was similar in 60FEC and 120FEC. No cumulative hematologic toxicity was observed for white blood cells (WBC) and platelets (PLT), while for hemoglobin (Hb) a somewhat higher cumulative toxicity was observed with 120FEC than with 60FEC. WBC, PLT and Hb grade III-IV toxicity occurred in 40.1% and 45.6% (P=ns), in 23.1% and 0.8% (P <.0001) and in 15.6% and 3.0% (P <.005) of the two regimens, respectively. There were no febrile or hemorrhagic episodes. The epirubicin relative dose intensity delivered was 1.95 in 120FEC with respect to 60FEC.

Conclusions

Our G-CSF schedule permitted to deliver six courses of 120FEC without any clinically relevant side effects. Grade III-IV leukopenia was similar with 120FEC and 60FEC, while grade III-IV thrombocytopenia and anemia occurred more often with 120FEC than with 60FEC.

Variation in cell yield and proliferative activity of positive selected human CD34+ bone marrow cells along the circadian time scale

Variations in cell yield and proliferative activity of human bone marrow (BM) progenitor cells were determined with flow cytometry along the 24-h (circadian) time scale. Equal volumes of BM were aspirated every 5 h, altogether 5 times in 5 healthy men. An average 6-fold higher yield of positive selected CD34+ cells occurred in each subject when BM was aspirated during the daytime and late afternoon, while a lower yield occurred during the night. Using all CD34+ cell yield data normalized to percentage of mean, a significant time-effect was found by ANOVA (p = 0.02) and a significant circadian rhythm was detected by the least-squares fit of a 24 h cosine (p = 0.02). The 95% confidence limits of the acrophase (time of highest values) were computed to be at midday between 10:24 and 14:48 h. A highly significant correlation (p = 0.001) was found between proliferation of positive selected CD34+ cells and the more mature myeloid precursor cells from the same BM aspirates, suggesting a common temporal pattern along the circadian time scale. However, no correlation was demonstrated between proliferation and cell yield of CD34+ selected cells, suggesting that mechanisms other than variation in proliferation may cause the circadian rhythm in stem cell yield. These circadian variations in stem cell yield and proliferation suggest that proper timing within 24 h may potentially be important regarding outcome from progenitor cell harvesting and treatment with haematopoietic growth factors.