Biologicals and Hematopoietic Cytokines in Prevention or Treatment of Infections in Immunocompromised Hosts

Genetic toxicity of cytokines

Review of the literature shows that such cytokines as human interferons alpha and gamma, tumor necrosis factor alpha, epidermal growth factor and interleukin-2 may exhibit genotoxic properties in human peripheral blood lymphocyte cultures. For all above cytokines, except interleukin-2, parabolic-like relationship between the dose and the frequency of sister chromatid exchanges was found. Although the mechanisms of these genotoxic actions remain largely unknown, generation of free radicals or interaction with enzymes such as DNA topoisomerase II may be suspected. Human interferon alpha also may be considered as an antimutagenic compound in human cells. Human tumor necrosis factor alpha has been reported to enhance cytotoxicity and DNA fragmentation produced by DNA topoisomerase II-targeted anticancer drugs. At the same time, it has some radio- and chemoprotective properties in vitro and in vivo. Despite these facts, the question about genotoxicity of cytokines is not answered. Some problems must be resolved before receiving the final answer. First, much more cytokines must be tested for their genotoxic activity. Second, appropriate test-systems must be designed. Third, genotoxicity studies of cytokines must account for cytokine interaction in the cytokine network as well as for such cytokine-induced effects as cytotoxicity and apoptosis. Fourth, in each case, it is necessary to have experimental evidence that observed genotoxic effects were caused by cytokine under investigation and not by the other factors.

Fever in the neutropenic host

Fever in the neutropenic patient following myelosuppressive chemotherapy is a medical emergency. Appropriate antimicrobial therapy can dramatically reduce infection-related morbidity and mortality. This article reviews the rationale and methodology of treatment as well as its applicability to other neutropenic states. The utility of adjunct therapy with granulocyte- stimulating compounds is also discussed.

Impairment of non-specific immunity in patients in persistent vegetative state

In fourteen patients in persistent vegetative state (PVS) immune responsiveness was investigated. In particular, we studied the relationship between brain lesions following traumatic injury and immune system. In this respect, phagocytosis and killing of Candida albicans by polymorphonuclear cells (PMN) and monocytes were tested. In addition serum levels of Interferon-gamma (IFN-gamma) were evaluated. The patients come out from PVS by 3-4 month were used as control group. Data shown a profound impairement of phagocytosis and killing of monocytes and low serum levels of IFN gamma when compared with normal values. Taken together, these findings suggest that brain lesions, may affect non-specific immune response.

An approach to the design and implementation of clinical trials of empirical antibiotic therapy in febrile and neutropenic cancer patients

The results of many clinical trials on empirical therapy in febrile, neutropenic cancer patients cannot be readily transferred to the clinical practice, because the methodology is often flawed and definitions, study endpoints and eligibility criteria differ from trial to trial. This article critically reviews some issues related to the design and implementation of randomised clinical trials of empirical antibiotic therapy in cancer patients. Within the definition of phase III clinical trials, two approaches co-exist, based on the trial's specific aims: the "explanatory" approach and the "pragmatic" approach. The usual "explicit" aim of clinical trials of empirical therapy in febrile, neutropenic patients has been that of comparing the "efficacy" of two regimens. However, this term has been more often used with reference to the antibacterial activity of the regimen under study (explanatory aim) than to indicate the practical benefits it draws to the overall patient population treated for fever and neutropenia (pragmatic aim). These two meanings are often taken as perfectly interchangeable, while, conversely, they are completely distinct (though not independent) treatment effects. Most trials conducted in this patient population in recent years are explanatory trials, though not explicitly so, but their results have been widely applied to clinical practice, as they were pragmatic trials. In an explanatory trial the appropriate endpoint is success or failure (defined by clinical and laboratory data) among those patients affected with the specific infection for which the study drug is being given, while in pragmatic trials survival is probably the more appropriate outcome variable, since they are designed to assess the practical benefits that the overall population of febrile and neutropenic patients can obtain from the new empirical treatment. Unfortunately, survival is not a practical study endpoint for the difficulty in assessing the cause of death in this patient population and, especially, for the need for very large sample sizes, which might render the implementation problematic even for large, multicentre groups. Both types of trials need an intention to treat analysis, but this is especially crucial for pragmatic trials, which should not differentiate those cases in which success was obtained through multiple treatment modifications from those who did not require any treatment change. Obviously, this implies that no conclusion should be drawn about the antibacterial activity of the study drugs and that the number of treatment modifications should be taken into account in the interpretation of the results, especially for quality of life and cost evaluations. Information related to fever and signs of infection, age, underlying disease, neutropenia and concomitant administration of other antibiotics are crucial entry criteria that need to be clearly discussed and defined. Finally, the evaluation of toxicity is problematic in this patient population, due to the existence of a number of toxigenic factors, including the underlying disease, the type of infectious complication, the administration of chemotherapy and radiotherapy and the use of parental nutrition. All these effects tend to overlap, thus impairing the investigator's ability to detect specific drug-related side-effects.

Feasibility of outpatient management of fever in cancer patients with low-risk neutropenia: results of a prospective randomized trial

PURPOSE

We recently demonstrated the efficacy of single-agent oral ofloxacin in the management of hospitalized neutropenic febrile patients. Ofloxacin was particularly effective in patients with short duration of neutropenia and fever of undetermined origin. These results prompted us to study the feasibility of outpatient management of neutropenic febrile patients who are otherwise at low risk of morbidity and mortality.

PATIENTS AND METHODS

This multi-institutional, prospective, randomized trial included 182 low-risk neutropenic febrile episodes. After an initial work-up for fever, patients were randomized to receive oral ofloxacin 400 mg immediately and twice daily thereafter in the hospital or as outpatients. Close monitoring and follow-up were carried out in all patients. Those who failed to respond and remained febrile were given parenteral antibiotics. Nonresponding outpatients were admitted to the hospital for parenteral therapy.

RESULTS

One hundred sixty-nine episodes were evaluable. The hospital and outpatient treatment groups had comparable clinical characteristics. Pyrexias of undetermined origin (PUO) comprised 69% of episodes managed in hospital and 73% of episodes treated outside. The success rate with PUO was similar with inpatient and outpatient management. Patients with clinical and microbiologic infections fared less well than those with PUO. Overall, 78% of inpatient and 77% of outpatient fevers resolved with no modification of the initial treatment. Twenty-one percent of patients originally assigned to outside management required hospitalization. Mortality was 2% among inpatients and 4% among outpatients. One early death in a nonhospitalized patient underscores the need for close monitoring and surveillance in these cases.

CONCLUSIONS

Outpatient management of low-risk neutropenic febrile patients with ofloxacin is as effective as inpatient management with the same agent. This approach should be limited to the subset of patients with low-risk factors who are not otherwise on quinolone prophylaxis.