T-cell abnormalities after mediastinal irradiation for lung cancer. The in vitro influence of synthetic thymosin alpha-1

A Reappraisal of Thymosin Alpha1 in Cancer Therapy

Thymosin alpha1 (Tα1), an endogenous peptide first isolated from the thymic tissue in the mid-sixties, has gained considerable attention for its immunostimulatory activity that led to its application to diverse pathological conditions, including cancer. Studies in animal models and human patients have shown promising results in different types of malignancies, especially when Tα1 was used in combination with other chemo- and immune therapies. For this reason, the advancements in our knowledge on the adjuvant role of Tα1 have moved in parallel with the development of novel cancer therapies in a way that Tα1 was integrated to changing paradigms and protocols, and tested for increased efficacy and safety. Cancer immunotherapy has recently experienced a tremendous boost following the development and clinical application of immune checkpoint inhibitors. By unleashing the full potential of the adaptive immune response, checkpoint inhibitors were expected to be very effective against tumors, but it soon became clear that a widespread and successful application was not straightforward and shortcomings in efficacy and safety clearly emerged. This scenario led to the development of novel concepts in immunotherapy and the design of combination protocols to overcome these limitations, thus opening up novel opportunities for Tα1 application. Herein, we summarize in a historical perspective the use of Tα1 in cancer, with particular reference to melanoma, hepatocellular carcinoma and lung cancer. We will discuss the current limitations of checkpoint inhibitors in clinical practice and the mechanisms at the basis of a potential application of Tα1 in combination protocols.

Standard radiotherapy but not chemotherapy impairs systemic immunity in non-small cell lung cancer

Introduction: Advanced non-small cell lung cancer (NSCLC) is traditionally treated with platinum-based chemotherapy and radiotherapy. Since immunotherapy holds promise for treating advanced NSCLC, we assessed the systemic effects of the traditional therapies for NSCLC on immune cell composition and function.

Methods: 84 pulmonary adenocarcinoma patients, treated either with chemotherapy or radiotherapy, were studied. A prospective study of 23 patients was conducted in which the myeloid and lymphoid cell compartments of peripheral blood were analyzed. Changes in cell populations were validated in a retrospective cohort of 61 adenocarcinoma patients using automated differential counts collected throughout therapy. Furthermore, the functional capacity of circulating T cells and antigen-presenting cells (APC) was studied. Blood samples of healthy individuals were used as controls.

Results: In comparison to healthy controls, untreated adenocarcinoma patients display an elevated frequency of myeloid cells coinciding with relative lower frequencies of lymphocytes and dendritic cells. Standard chemotherapy had no overt effects on myeloid and lymphoid cell composition nor on T-cell and APC-function. In contrast, patients treated with radiotherapy displayed a decrease in lymphoid cells and a relative increase in monocytes/macrophages. Importantly, these changes were associated with a reduced APC function and an impaired response of T cells to recall antigens.

Conclusions: Platinum-based standard of care chemotherapy for NSCLC has no profound negative effect on the immune cell composition and function. The negative effect of prolonged low-dose radiotherapy on the immune system warrants future studies on the optimal dose and fraction of radiotherapy when combined with immunotherapy.

Influence of multimodality therapy on the cellular immunity of patients with esophageal cancer

BACKGROUND

Cancer patients have often been reported to have impaired immune function, and the effect of treatment modalities, such as surgery, irradiation, and chemotherapy, in depressing patients' immunity has also been reported. In this investigation, the effect of treatment on the cellular immunity of esophageal cancer patients was evaluated.

METHODS

Immunological parameters, such as natural killer (NK) activity and lymphocyte subsets in peripheral blood, were measured in 32 esophageal cancer patients on 5 occasions (on the day of admission, 2 days before surgery, and 1 week, 1 month, and 2 months after surgery).

RESULTS

NK activity was greatly impaired shortly after the operation, and the percentages of lymphocytes as a whole, and CD8+, CD16+, and CD57+ lymphocytes were significantly decreased, on the other hand, a postoperative increase in the CD4+/CD8+ ratio was observed. No significant depression of immune function by postoperative irradiation was observed.

CONCLUSIONS

The results of this study suggest that cellular immunity, especially cytotoxicity, shortly after esophagectomy may be greatly impaired by the surgical stress of esophagectomy and an added effect of chemotherapy.

Multicolor flow cytometry analysis of blood cell subsets in patients given total body irradiation before bone marrow transplantation

PURPOSE

Bone marrow transplantation has often been closely linked with accidental or intentional therapeutical irradiation. In both situations, study of the radiosensitivity of human blood cell subsets is of interest. Using one-color flow cytometry analysis of B lymphocytes, T cell subsets, and natural killer cells, we previously reported that lymphocyte subsets exhibit equal radiosensitivity. Taking advantage of recent developments in the knowledge of leukocyte differentiation antigens and flow cytometry technology we undertook a study of blood cell subsets to search for rare populations exhibiting different radiosensitivity.

METHODS AND MATERIALS

Thirty patients, who were delivered a 12 Gy fractionated total body irradiation as part of their conditioning regimen before transplantation for malignant disorders, were studied using multicolor flow cytometry.

RESULTS

T and B lymphocytes showed a sharp, radiation-induced decrease, with the B lymphocytes (cluster of differentiation (CD) 19+) being the most sensitive. When analyzed by multicolor flow cytometry, all major lymphocyte subsets appeared equally sensitive to the in vivo irradiation; that is, CD3+4+45RO+, CD3+4+45RA+, CD3+4+8-, CD3+4-8+. Therefore, all major lymphocyte subsets sharing the helper phenotype (naive or memory) and the cytotoxic phenotype appeared equally sensitive to in vivo whole body irradiation. In parallel, the CD34+ cell subset remained basically unchanged after whole body irradiation. Finally, the CD3-, 56+, 16+ natural killer cell subset was relatively radioresistant (91 and 74% of its initial value, after 2 and 4 Gy, respectively) as compared to other lymphocyte subsets.

CONCLUSION

Our study provides evidence that T and B cell subsets seem to be highly radiosensitive in vivo. The CD34+ progenitor/stem cells and NK cells seem to be more radioresistant. This latter result might provide clues to the understanding of the pathophysiogeny of radiation-induced aplasia and of the engrafment/rejection process following bone marrow transplantation.

The effect of radiation therapy on immune function in patients with squamous cell lung carcinoma

The immune response is impaired in patients with malignancy, and radiation therapy (RT) can exacerbate the cancer induced-attenuation of immune response. In order to search for the fine mechanisms behind the RT-induced attenuation of cell-mediated immune response, we measured the number of lymphocytes in peripheral blood, its subsets, and lymphoblast transformation induced by phytohemagglutinin (PHA), purified protein derivatives (PPD), mitogenic monoclonal antibody anti-CD3, and mitogenic combination of anti-CD2 antibodies 9-1 and 9.6 before and after RT in 19 patients with squamous cell lung cancer. Radiation therapy significantly decreased the total numbers of lymphocytes, CD-3, CD-4, and CD8-positive lymphocytes in peripheral blood. However, RT did not change the percentages of lymphocytes and its subsets. Radiation therapy increased the percentage of interleukin 2 (IL-2) receptor-positive lymphocytes, and RT significantly decreased in vitro lymphoblast transformation by PHA, PPD, or monoclonal antibodies to T-cell surface antigens (anti-CD2 or anti-CD3). In vitro incubation with IL-2 did not increase lymphoblast transformation by anti-CD3 before RT but significantly increased after RT. In conclusion, we suggest that one of the fine mechanisms behind the RT-induced suppression of immune responsiveness of patients with lung cancer is a defect in IL-2 synthesis by lymphocytes.

A complete response of an advanced oesophageal carcinoma treated with hyperthermic chemotherapy: a case report

A 56-year-old Japanese man with an advanced squamous cell carcinoma in the middle oesophagus was treated with a combination of hyperthermia, intravenous infusion of cisplatin (CDDP) and oral administration of oily bleomycin(BLM)-polyacrylate paste. After performing six sessions of hyperthermia treatment conducted at 42-45 degrees C for 30 min with 150 mg of CDDP and 180 mg of BLM, a subtotal oesophagectomy and lymph node dissection were performed. A histopathological study of the resected specimen showed no residual viable cancer cells either in the oesophagus or in the dissected lymph nodes. There were no side effects or perioperative complications and the patient is now healthy and leading a normal life 10 months after operation without undergoing any further treatment, at the time of writing. The effect of small amounts of CDDP and the oral application of oily BLM were thought to be strongly enhanced by hyperthermia in the treatment of oesophageal squamous carcinoma, and this regimen is therefore recommended as a safe and effective strategy, especially for preoperative treatment.

Influence of preoperative treatment and surgical operation on immune function of patients with esophageal carcinoma

Multiple immunological parameters, including total lymphocyte count, lymphocyte subpopulations (CD2+, CD19+, CD3+, CD4+ and CD8+), phytohemagglutinin (PHA) response, and natural killer (NK) activity, were measured in 66 patients with previously untreated esophageal carcinoma. The influence of preoperative treatment and/or surgical operation on the immune function were evaluated in 40 patients. The PHA response and NK activity of the patients with esophageal carcinoma were 229 +/- 103 S.I.% and 18.5 +/- 11.9% lysis, respectively, and were significantly depressed as compared with the control. The CD4+/CD8+ ratio, PHA response, and NK activity in stage IV were also significantly depressed compared to that in stages I-III. Preoperative treatment induced significant reductions in the total lymphocyte count (1,994 +/- 644 to 670 +/- 274/mm3), PHA response (219 +/- 77 to 159 +/- 59 S.I.%), and NK activity (19.7 +/- 13.2 to 11.1 +/- 10.3% lysis) as well as a significant gradual decrease in the CD4+/CD8+ ratio (2.09 +/- 1.42 to 0.69 +/- 0.48), while the surgical operation significantly influenced only the total lymphocyte count. This study demonstrates that preoperative treatment induces a more pronounced influence on the immune function than surgical operation alone, in patients with esophageal carcinoma in which the immune function is disturbed prior to these treatments.

Lymphocyte subset distribution after radiation therapy for cancer of the uterine cervix. Possible prognostic implications and correlation with disease course

An analysis of lymphocyte subpopulations was done in patients with cancer of the uterine cervix before and at different intervals after the commencement of radiation therapy. A common feature was a duration of T-cell and B-cell lymphopenia after therapy. The findings relating to the T-cell subsets were interesting. Although the CD4/CD8 ratio remained unchanged in Stages I/IIA for 24 months after treatment, patients with Stages IIB and III showed a lowering of the ratio immediately after treatment. Distinctive patterns of lymphocyte subset distribution were seen in a comparison between patients who were disease-free and those with recurrent disease. The CD4+ cell counts and CD4/CD8 ratio differed between the two groups, with consistent lowered values during the follow-up associated with recurrent disease. This study demonstrates the effects of radiation therapy in altering lymphocyte subset distribution, resulting in characteristic patterns which could be used as clinical and prognostic indicators.

Mechanisms involved in the differential recovery of CD4 and CD8 T-lymphocytes after local irradiation in mice

The mechanisms involved in the differential recovery of CD4 (helper/inducer phenotype) and CD8 (cytotoxic/suppressor phenotype) T-lymphocytes after fractionated local irradiation were investigated. In mice, a better recovery of CD4 cells than of CD8 cells was found, while the reverse has been described in humans. Differences in radiosensitivity between CD4 and CD8 mouse splenocytes could not be found. No sequestration of CD8 cells in irradiated tissues could be demonstrated. Irradiation of the thymus did not influence the observed immune changes. Altered thymic production of CD4 and CD8 cells could be excluded by intrathymic injection of FITC (fluorescein isothiocyanate). Hindlimb and tail irradiation did not induce changes in the morphology of the thymus and the phenotype of the thymocytes. These results suggest that the differential recovery of CD4 and CD8 T-lymphocytes after local irradiation is determined by extrathymic factors in man and mice, and that the observed differences in immune recovery between man and mice are due to defective thymic function in the former and normal function in the latter.

Immunologic changes after loco-regional radiotherapy and fractionated total body irradiation (TBI) in mice

The immunologic effects of fractionated irradiation to both hind limbs and the tail of adult (2.5-3 months old) male Balb/c mice were investigated. A dose of 34 Gy given in 17 fractions of 2 Gy, 1 fraction per day, 5 days per week, was delivered with a 60Co source. A significant decrease of the total splenocyte count (29% of control value) and of the PHA(phytohemagglutinin)-induced proliferation of T cells (22% of control value) was found immediately after irradiation. Both parameters normalized within 30 days after irradiation. Immediately after irradiation, the MLC (mixed lymphocyte culture) was supranormal (126% of control value), dropped to 45% 1 week later, and normalized within 1 month after radiotherapy. The NK (natural killer) activity was significantly decreased only the first week after loco-regional irradiation, while the LAK (lymphokine activated killer) activity was not altered at all. The percentage of goat-anti-mouse+ cells (mainly B lymphocytes) was not changed immediately after loco-regional irradiation, but rose to supranormal values (175% of control level) 3 months after irradiation. A persistent decrease of the percentage and the absolute numbers of the Lyt2+ cells (= CD8+ cells, suppressor/cytotoxic phenotype) was observed up to 3 months after irradiation, while the percentage of L3T4+ cells (= CD4+ cells, helper phenotype) remained normal for the total follow-up. No differences in allogeneic skin graft survival could be demonstrated between irradiated and control animals. The observed immunological effects could not be explained by the scatter irradiation to the whole body as total body irradiation (TBI) administered in a dose and dose rate similar to the scatter dose did not result in persistent immunologic changes. No dose-rate effect could be demonstrated in a low dose fractionated total body irradiation schedule. A total body irradiation similar to the scatter dose in humans did not result in significant immunologic changes.

Interleukin 2 and alpha interferon induced in vitro modulation of spontaneous cell mediated cytotoxicity in patients with cancer of the uterine cervix undergoing radiotherapy

In vitro modulation of spontaneous cell mediated cytotoxicity by interferon and interleukin 2 was carried out using peripheral blood lymphocytes from patients with cancer of the uterine cervix before and at different intervals after commencement of radiation treatment. A total of 150 patients with various stages of the disease were included and cytotoxicity was measured using the single cell cytotoxic assay. These results indicate a beneficial effect in vitro of interleukin 2 and interferon in augmenting spontaneous cell mediated cytotoxicity, a possibly vital antitumour immune mechanism in patients with relatively early cervix cancer. Natural killer cell, lymphokine activated killer cell and interferon activated killer cell activity was depressed immediately following radiotherapy. The activity of these cell types later on increased above pretreatment levels in patients with stages I, IIA and IIB. A similar rebound above pretreatment levels was not observed in patients with stages III and IV.

Blood cell kinetics and total body irradiation

The early response of blood cells to irradiation has been studied in leukemia patients who received total body irradiation (TBI) prior to cyclophosphamide and bone marrow transplantation. After a single session treatment (10 Gy in 4 h) the most dramatic variation was observed in the granulocytes. At the end of the irradiation their concentration was 2 to 6 times higher. Because of a subsequent rapid decline, the peak may be overlooked if the blood counts are delayed. Lymphocytes decreased to 50% at the end of the single session TBI and continue to decrease exponentially, with a half time of 30 h. During a fractionated irradiation (11 X 1.2 Gy in 4 days) the lymphocyte number dropped to 60%, 13 h after the first fraction and this decline continued with a half time of 30 h during the treatment. From the data obtained in vivo, a lymphocyte D0 value of 1.2 Gy was computed. The lymphocyte subsets (B.T. OKT4 OKT8) did not exhibit different radiosensitivities either in vivo or in vitro. The disappearance of lethally hit lymphocytes from the blood exhibits a biphasic kinetic: 50% of the cells disappear in a few hours and 50% with a half time at 30 h. Lymphocytes irradiated either in vitro or in vivo when in culture disappear slowly, contrasting with the in vivo findings. It may suggest that lethally hit lymphocytes are quickly removed from the circulating pool in vivo.

Thymic peptide hormones: basic properties and clinical applications in cancer

The manuscript will provide an in-depth and critical review of the nomenclature, biochemistry, biological properties, and a summary of published and on-going clinical trials with all reported thymic preparations, including both partially purified thymic factors (e.g., thymosin fraction 5, thymostimulin) as well as purified and synthesized thymic peptides (e.g., thymosin alpha 1, thymulin). Particular emphasis will be placed on which thymic peptides should be categorized as true hormones. In addition, the comparative biochemistry and biological activity in animals will be summarized and contrasted for all the currently available thymic factors. The effects, in vitro of thymic factors, on peripheral blood lymphocytes isolated from normal donors and patients with primary immunodeficiency disorders, autoimmune disorders, and neoplastic disorders will also be reviewed. Finally, a detailed critical summary of the clinical trials performed with each of the thymic preparations will be presented with an emphasis on treatment of patients with cancer.