Incidence of Infections in Adult Patients (> 55 Years) with Acute Myeloid Leukemia Treated with Yeast-Derived GM-CSF (Sargramostim): Results of a Double-Blind Prospective Study by the Eastern Cooperative Oncology Group

Recombinant Human Granulocyte-Macrophage Colony-Stimulating Factor (rhu GM-CSF) as Adjuvant Therapy for Invasive Fungal Diseases

BACKGROUND

Sargramostim (yeast-derived, glycosylated recombinant human granulocyte-macrophage colony-stimulating factor [rhu GM-CSF]) augments innate and adaptive immune responses and accelerates hematopoietic recovery of chemotherapy-induced neutropenia. However, considerably less is known about its efficacy as adjunctive immunotherapy against invasive fungal diseases (IFDs).

METHODS

The clinical courses of 15 patients with pediatric malignancies and IFDs treated adjunctively with sargramostim at a single institution were analyzed in a retrospective cohort review. Further, a systematic review of published reports of rhu GM-CSF for IFDs was also conducted.

RESULTS

Among 65 cases, 15 were newly described pediatric patients and 50 were previously published cases of IFDs treated with rhu GM-CSF. Among the newly reported pediatric patients, IFDs were caused by Candida spp., Trichosporon sp., and molds (Aspergillus spp., Rhizopus sp., Lichtheimia sp., and Scedosporium sp). Twelve (80%) were neutropenic at baseline, and 12 (80%) were refractory to antifungal therapy. Among 12 evaluable patients, the overall response rate was 92% (8 [67%] complete responses, 3 [25%] partial responses, and 1 [8%] stable). Treatment is ongoing in the remaining 3 patients. Among 50 published cases (15 Candida spp., 13 Mucorales, 11 Aspergillus spp., 11 other organisms), 20 (40%) had baseline neutropenia and 36 (72%) were refractory to standard therapy before rhu GM-CSF administration. Consistent with responses in the newly reported patients, the overall response rate in the literature review was 82% (40 [80%] complete responses, 1 [2%] partial response, and 9 [18%] no response).

CONCLUSIONS

Sargramostim may be a potential adjunctive immunomodulator for selected patients with hematological malignancies and refractory IFDs.

Sargramostim (rhu GM-CSF) as Cancer Therapy (Systematic Review) and An Immunomodulator. A Drug Before Its Time?

BACKGROUND

Sargramostim [recombinant human granulocyte-macrophage colony-stimulating factor (rhu GM-CSF)] was approved by US FDA in 1991 to accelerate bone marrow recovery in diverse settings of bone marrow failure and is designated on the list of FDA Essential Medicines, Medical Countermeasures, and Critical Inputs. Other important biological activities including accelerating tissue repair and modulating host immunity to infection and cancer via the innate and adaptive immune systems are reported in pre-clinical models but incompletely studied in humans.

OBJECTIVE

Assess safety and efficacy of sargramostim in cancer and other diverse experimental and clinical settings.

METHODS AND RESULTS

We systematically reviewed PubMed, Cochrane and TRIP databases for clinical data on sargramostim in cancer. In a variety of settings, sargramostim after exposure to bone marrow-suppressing agents accelerated hematologic recovery resulting in fewer infections, less therapy-related toxicity and sometimes improved survival. As an immune modulator, sargramostim also enhanced anti-cancer responses in solid cancers when combined with conventional therapies, for example with immune checkpoint inhibitors and monoclonal antibodies.

CONCLUSIONS

Sargramostim accelerates hematologic recovery in diverse clinical settings and enhances anti-cancer responses with a favorable safety profile. Uses other than in hematologic recovery are less-well studied; more data are needed on immune-enhancing benefits. We envision significantly expanded use of sargramostim in varied immune settings. Sargramostim has the potential to reverse the immune suppression associated with sepsis, trauma, acute respiratory distress syndrome (ARDS) and COVID-19. Further, sargramostim therapy has been promising in the adjuvant setting with vaccines and for anti-microbial-resistant infections and treating autoimmune pulmonary alveolar proteinosis and gastrointestinal, peripheral arterial and neuro-inflammatory diseases. It also may be useful as an adjuvant in anti-cancer immunotherapy.

Sargramostim (rhu GM-CSF) Improves Survival of Non-Human Primates with Severe Bone Marrow Suppression after Acute, High-Dose, Whole-Body Irradiation

Exposure to acute, high-dose, whole-body ionizing radiation results in bone marrow failure (hematopoietic acute radiation syndrome with resultant infection, bleeding, anemia, and increased risk of death). Sargramostim (yeast-derived rhu GM-CSF), a yeast-derived, molecularly cloned, hematopoietic growth factor and pleiotropic cytokine supports proliferation, differentiation, maturation and survival of cells of several myeloid lineages. We evaluated the efficacy of sargramostim in non-human primates (rhesus macaques) exposed to whole-body ionizing radiation at a 50-60% lethal dose. The primary end point was day 60 survival. Non-human primates received daily subcutaneous sargramostim (7 mcg/kg/day) or control. To reflect the anticipated setting of a nuclear or radiologic event, treatment began 48 h postirradiation, and non-human primates received only moderate supportive care (no whole blood transfusions or individualized antibiotics). Sargramostim significantly increased day 60 survival to 78% (95% confidence interval, 61-90%) vs. 42% (26-59%; P = 0.0018) in controls. Neutrophil, platelet and lymphocyte recovery rates were accelerated and infection rates decreased. Improved survival when sargramostim was started 48 h postirradiation, without use of intensive supportive care, suggests sargramostim may be effective in treating humans exposed to acute, high-dose whole-body, ionizing radiation in a scenario such as a mass casualty event.

Use of molecularly-cloned haematopoietic growth factors in persons exposed to acute high-dose, high-dose rate whole-body ionizing radiations

Exposure to acute, high-dose, high dose-rate whole-body ionizing radiations damages the bone marrow resulting in rapid decreases in concentrations of blood cells, especially lymphocytes, granulocytes and platelets with associated risks of infection and bleeding. In several experimental models including non-human primate radiation exposure models giving molecularly cloned haematopoietic growth factor including granulocyte/macrophage colony-stimulating factor (G/M-CSF; sargramostim) and granulocyte colony-stimulating factor (G-CSF; filgrastim and pegylated G-CSF [peg-filgrastim]) accelerates bone marrow recovery and increases survival. Based on these data these molecules are US FDA approved for treating victims of radiation and nuclear incidents, accident and events such as nuclear terrorism and are included in the US National Strategic Stockpile. We discuss the immediate medical response to these events including how to estimate radiation dose and uniformity and which interventions are appropriate in different radiation exposures settings. We also discuss similarities and differences between molecularly cloned haematopoietic growth factors.

Economic analysis of granulocyte colony stimulating factor as adjunct therapy for older patients with acute myelogenous leukemia (AML): estimates from a Southwest Oncology Group clinical trial

Considerable morbidity, mortality, and economic costs result during remission induction therapy for elderly patients with acute myeloid leukemia (AML). In this study, the economic costs of adjunct granulocyte colony stimulating factor (G-CSF) are estimated for AML patients > 55 years of age who received induction chemotherapy on a recently completed Southwest Oncology Group study (SWOG). Clinical data were based on Phase III trial information from 207 AML patients who were randomized to receive either placebo or G-CSF post-induction therapy. Analyses were conducted using a decision analytic model with the primary source of clinical event probabilities based on in-hospital care with or without an active infection requiring intravenous antibiotics. Estimates of average daily costs of care with and without an infection were imputed from a previously reported economic model of a similar population. When compared to AML patients who received placebo, patients who received G-CSF had significantly fewer days on intravenous antibiotics (median 22 vs. 26, p = 0.05), whereas overall duration of hospitalization did not differ (median 29 days). The median cost per day with an active infection that required intravenous antibiotics was estimated to be $1742, whereas the median cost per day without an active infection was estimated to be $1467. Overall, costs were $49,693 for the placebo group and $50,593 for the G-CSF patients. G-CSF during induction chemotherapy for elderly patients with AML had some clinical benefits, but it did not reduce the duration of hospitalization, prolong survival, or reduce the overall cost of supportive care. Whether the benefits of G-CSF therapy justify its use in individual patients with acute leukemia for the present remains a matter of clinical judgment.

Cost analyses of adjunct colony stimulating factors for acute leukemia: can they improve clinical decision making

Colony stimulating factors reduce the duration of neutropenia following intensive chemotherapy in a variety of settings, but the advantages in the management of leukemia are inconclusive. The variations in clinical results and the high costs of granulocyte colony-stimulating factor (G-CSF) and granulocyte macrophage colony-stimulating factor (GM-CSF) have led to confusion over appropriate use for leukemia patients. In this paper, we reviewed published information on costs and cost-effectiveness of growth factors for childhood and adult leukemia patients. Medline and Healthstar databases were searched for original research articles that contain cost or cost-effectiveness analyses of G-CSF (filgrastim) and GM-SCF (sargramostim) in oncology cooperative group trials. Published manuscripts and abstracts presented at national or international oncology conferences were included. The cost of adjunct treatment was evaluated in two studies of pediatric ALL, one study of adult AML, and two studies of AML in older adults (>55 years). The use of G-CSF for children with ALL was associated with reductions in days to ANC recovery, fewer documented infections, a shorter duration of hospitalization, and small (but not significant) additional costs. In adult AML patients, benefits included a shortening of the duration of neutropenia and hospital stays, a lower incidence of infection and febrile episodes, less use of antibiotics, and cost savings of $2,230 and $2,310 in two studies and an increase if $120 in the third study. This summary suggests that economic analyses can provide useful information to assist clinical decision-making. For pediatric ALL patients, this information indicates that G-CSF use is unlikely to have significant cost implications, and its use should be based on clinical considerations. In studies of adult and older adult AML patients, both GM-CSF and G-CSF have clinical benefits and can be expected to lead to a decrease in overall costs.

Economic analyses of phase III cooperative cancer group clinical trials: are they feasible?

Both economic and clinical evaluations of new pharmaceutical agents are important to physicians who practice in the current health care environment. While cooperative cancer groups carry out large-scale phase III clinical evaluations of these agents, few cooperative group studies incorporate economic analyses because of concerns over overburdening of data management, investigators, and statistical center personnel. In this study, we describe the results and operational considerations of one of the first completed economic analyses of a phase III cooperative group trial of the Eastern Cooperative Oncology Group (ECOG). We developed an economic model estimating economic benefits of yeast-derived granulocyte-macrophage colony-stimulating factor (GM-CSF) as adjunct therapy for adult patients (56-70 years) with acute myelogenous leukemia. Clinical data were based on prospectively collected information from a recently reported double-blind phase III multi-institutional study carried out by ECOG. Retrospective economic data were obtained from financial information systems at our hospital, one of the study sites. The cost-minimization analyses were based on the perspective of a third-party payer. Indirect costs related to loss of earnings by patients and caregivers as well as quality-of-life adjustments were not incorporated into the model. Clinical trial results indicated that patients treated with GM-CSF had shorter times to recovery of absolute neutrophil count of 500 cells/mm3 and 1000 cells/mm3 and fewer serious infections than patients who received placebo following induction chemotherapy, while no significant differences were noted in red blood cell and platelet transfusion dependency, toxicities, and duration of hospitalization. The economic model estimated that the group treated with GM-CSF was estimated to have lower costs of care, associated with lower frequencies of serious infections and lower overall infection-related costs. Sensitivity analyses indicated that these results held true over a wide range of estimates of costs and infection rates. Prospective economic analyses of phase III cooperative cancer group clinical trials have not been completed to date. Strategies that are not likely to overburden data managers and statistical center personnel are possible to devise. However, these studies require careful planning and coordination between clinical trialists, economists, and health services researchers.