The effects of therapeutic irradiation on lymphocytes and immunity

Current Prospects for Treatment of Solid Tumors via Photodynamic, Photothermal, or Ionizing Radiation Therapies Combined with Immune Checkpoint Inhibition (A Review)

Photodynamic therapy (PDT) causes selective damage to tumor cells and vasculature and also triggers an anti-tumor immune response. The latter fact has prompted the exploration of PDT as an immune-stimulatory adjuvant. PDT is not the only cancer treatment that relies on electromagnetic energy to destroy cancer tissue. Ionizing radiation therapy (RT) and photothermal therapy (PTT) are two other treatment modalities that employ photons (with wavelengths either shorter or longer than PDT, respectively) and also cause tissue damage and immunomodulation. Research on the three modalities has occurred in different “silos”, with minimal interaction between the three topics. This is happening at a time when immune checkpoint inhibition (ICI), another focus of intense research and clinical development, has opened exciting possibilities for combining PDT, PTT, or RT with ICI to achieve improved therapeutic benefits. In this review, we surveyed the literature for studies that describe changes in anti-tumor immunity following the administration of PDT, PTT, and RT, including efforts to combine each modality with ICI. This information, collected all in one place, may make it easier to recognize similarities and differences and help to identify new mechanistic hypotheses toward the goal of achieving optimized combinations and tumor cures.

Combined Treatment of Radiotherapy and Immunotherapy for Urological Malignancies: Current Evidence and Clinical Considerations

Although it has always been believed that radiation has immunosuppressive effects, more and more preclinical and clinical trials have shown that the combination of radiotherapy and immunotherapy has a potential synergistic effect to treat cancers including urological malignancies. When radiotherapy is combined with immunotherapy, improved prognosis has been observed in different urinary tumors. However, there is no standard treatment, such as the optimal dose/fractionation and the sequence of immunotherapy and radiotherapy. In this review, we discussed the effects of radiotherapy on the cancer immune system and emphasized the synergy of radiotherapy combined with immunotherapy. Although it has significantly improved the prognosis of tumors, there are still some unresolved questions about how to best use this combination in clinical practice. Ongoing trials will provide further information on the interaction of radiotherapy combined with immunotherapy, and are expected to guide clinical practice and improve clinical outcomes.

Impact of concomitant systemic treatments on toxicity and intracerebral response after stereotactic radiotherapy for brain metastases

Background

The aim of this study was to determine the safety and efficacy of fractionated stereotactic radiotherapy (SRT) in combination with systemic therapies (ST) for brain metastases (BM).

Methods

Ninety-nine patients (171 BM) received SRT and concurrent ST (group 1) and 95 patients (131 BM) received SRT alone without concurrent ST (group 2). SRT was planned on a linear accelerator, using volumetric modulated arc therapy. All ST were allowed including chemotherapy (CT), immunotherapy (IT), targeted therapy (TT) and hormonotherapy (HT). Treatment was considered to be concurrent if the timing between the drug administration and SRT did not exceed 1 month. Local control (LC), freedom for distant brain metastases (FFDBM), overall survival (OS) and radionecrosis (RN) were evaluated.

Results

After a median follow-up of 11.9 months (range 0.7–29.7), there was no significant difference between the two groups. However, patients who received concurrent IT (n = 30) had better 1-year LC, OS, FFDBM but a higher RN rate compared to patients who did not: 96% versus 78% (p = 0.02), 89% versus 77% (p = 0.02), 76% versus 53% (p = 0.004) and 80% versus 90% (p = 0.03), respectively. In multivariate analysis, concurrent IT (p = 0.022) and tumor volume < 2.07 cc (p = 0.039) were significantly correlated with improvement of LC. The addition of IT to SRT compared to SRT alone was associated with an increased risk of RN (p = 0.03).

Conclusion

SRT delivered concurrently with IT seems to be associated with improved LC, FFDBM and OS as well as with a higher rate of RN.

Abscopal effect of high-dose-rate brachytherapy on pelvic bone metastases from renal cell carcinoma: a case report

Radiation therapy is considered an optimal partner for immunotherapies. Several pre-clinical studies have demonstrated that regression of distant metastases, at remote non-irradiated sites of the body, termed the “abscopal effect”, can be achieved by an appropriate timing and combination of radiation with immunotherapy. However, nearly all pre-clinical and clinical studies evaluating a combination of radiation and immunotherapies have used external beam radiation therapy. We present in this case report, the abscopal effect observed in a 30-year-old Japanese woman with metastatic renal cell carcinoma after the treatment with high-dose-rate interstitial brachytherapy combined with nivolumab. This is the first published report demonstrating an abscopal effect following brachytherapy for human malignancy. Our case indicates that immuno-oncology effects are not limited to external beam irradiation regimens as they can also be attained by brachytherapy.

Stereotactic Body Radiation and Interleukin-12 Combination Therapy Eradicates Pancreatic Tumors by Repolarizing the Immune Microenvironment

Over 80% of pancreatic ductal adenocarcinoma (PDA) patients are diagnosed with non-resectable late-stage disease that lacks effective neoadjuvant therapies. Stereotactic body radiation therapy (SBRT) has shown promise as an emerging neoadjuvant approach for treating PDA, and here, we report that its combination with local interleukin-12 (IL-12) microsphere (MS) immunotherapy results in marked tumor reduction and cures in multiple preclinical mouse models of PDA. Our findings demonstrate an increase of intratumoral interferon gamma (IFNγ) production following SBRT/IL-12 MS administration that initiates suppressor cell reprogramming and a subsequent increase in CD8 T cell activation. Furthermore, SBRT/IL-12 MS therapy results in the generation of systemic tumor immunity that is capable of eliminating established liver metastases, providing a rationale for follow-up studies in advanced metastatic disease.

Combining Radiotherapy With Anti-angiogenic Therapy and Immunotherapy; A Therapeutic Triad for Cancer?

Radiotherapy has been used for the treatment of cancer for over a century. Throughout this period, the therapeutic benefit of radiotherapy has continuously progressed due to technical developments and increased insight in the biological mechanisms underlying the cellular responses to irradiation. In order to further improve radiotherapy efficacy, there is a mounting interest in combining radiotherapy with other forms of therapy such as anti-angiogenic therapy or immunotherapy. These strategies provide different opportunities and challenges, especially with regard to dose scheduling and timing. Addressing these issues requires insight in the interaction between the different treatment modalities. In the current review, we describe the basic principles of the effects of radiotherapy on tumor vascularization and tumor immunity and vice versa. We discuss the main strategies to combine these treatment modalities and the hurdles that have to be overcome in order to maximize therapeutic effectivity. Finally, we evaluate the outstanding questions and present future prospects of a therapeutic triad for cancer.

Rationale for combination of radiation therapy and immune checkpoint blockers to improve cancer treatment

Radiation therapy for cancer is considered to be immunosuppressive. However, the cellular response after radiation therapy may stimulate or suppress an immune response. The effect may vary with the tumor type and occasionally tumor regressions have been observed outside the irradiated volume, both in animal studies and in the clinic. A renewed interest in the role of immunity for the observed effect of radiation came with the current recognized role of immune checkpoint blockers (ICBs) for control of selected cancer types. We therefore here review preclinical studies and clinical reports on the interaction of ICBs and radiation as a basis for further clinical trials. Some tumor types where the combination of these modalities seems especially promising are also proposed.

α-PD-L1 mAb enhances the abscopal effect of hypo-fractionated radiation by attenuating PD-L1 expression and inducing CD8+ T-cell infiltration

AIM

We investigated a promising cooperative combination of radiotherapy (RT) and programmed death ligand 1 (PD-L1) monoclonal antibodies (mAb) in both local and abscopal tumors.

MATERIALS & METHODS

C57BL/6 mice were randomly grouped and received RT, α-PD-L1 mAb or combination therapy 13 days after implantation of Lewis lung carcinoma cells. Flow cytometry and immunohistochemistry analyses demonstrated CD8⁺ T-cell infiltration and PD-L1 expression in tumor issue. Cytometric bead arrays were used to examine cytokine levels.

RESULTS

Our studies revealed that administration of 8 Gy × 3 F with α-PD-L1 mAb promoted both local and distant control. Only local hypofractionated RT enhanced CD8⁺ T-cell infiltration with increased PD-L1 expression at distant foci, which might occur via serum IFN-γ modulation. Addition of α-PD-L1 mAb reduced PD-L1 expression and further increased CD8⁺ T-cell infiltration.

CONCLUSION

We identified a novel mechanism through which combination therapy enhanced the abscopal effect.

Combining brachytherapy and immunotherapy to achieve in situ tumor vaccination: A review of cooperative mechanisms and clinical opportunities

As immunotherapies continue to emerge as a standard component of treatment for a variety of cancers, the imperative for testing these in combination with other standard cancer therapies grows. Radiation therapy may be a particularly well-suited partner for many immunotherapies. By modulating immune tolerance and functional immunogenicity at a targeted tumor site, radiation therapy may serve as a method of in situ tumor vaccination. In situ tumor vaccination is a therapeutic strategy that seeks to convert a patient's own tumor into a nidus for enhanced presentation of tumor-specific antigens in a way that will stimulate and diversify an antitumor T cell response. The mechanisms whereby radiation may impact immunotherapy are diverse and include its capacity to simultaneously elicit local inflammation, temporary local depletion of suppressive lymphocyte lineages, enhanced tumor cell susceptibility to immune response, and immunogenic tumor cell death. Emerging data suggest that each of these mechanisms may display a distinct dose-response profile, making it challenging to maximize each of these effects using external beam radiation. Conversely, the highly heterogenous and conformal dose distribution achieved with brachytherapy may be optimal for enhancing the immunogenic capacity of radiation at a tumor site while minimizing off-target antagonistic effects on peripheral immune cells. Here, we review the immunogenic effects of radiation, summarize the clinical rationale and data supporting the use of radiation together with immunotherapies, and discuss the rationale and urgent need for further preclinical and clinical investigation specifically of brachytherapy in combination with immunotherapies. Harnessing these immunomodulatory effects of brachytherapy may offer solutions to overcome obstacles to the efficacy of immunotherapies in immunologically "cold" tumors while potentiating greater response in the context of immunologically "hot" tumors.

Significance of tumor-infiltrating lymphocytes before and after neoadjuvant therapy for rectal cancer

Neoadjuvant therapy for locally advanced rectal cancer is becoming increasingly common. However, biomarkers predicting the response to neoadjuvant therapy have not been established. Tumor‐infiltrating lymphocytes (TILs) have a crucial effect on tumor progression and survival outcome as the primary host immune response, and an antitumor immune effect has been reported to contribute to the response to radiotherapy and chemotherapy. We investigated the significance of TILs before and after neoadjuvant treatment and the change in the density of those TILs. Sixty‐four patients who underwent radical resection after neoadjuvant treatment for locally advanced rectal cancer were enrolled. The number of TIL subsets was examined using immunohistochemical staining of pretreatment biopsy samples and post‐treatment resected specimens. In both the neoadjuvant chemotherapy cohort and the neoadjuvant chemoradiotherapy cohort, a low density of CD8⁺TILs in pretreatment biopsy samples was associated with a poor response, and a low density of CD8⁺TILs in post‐treatment resected specimens was similarly associated with a poor response. In the neoadjuvant chemoradiotherapy cohort, the density of CD8⁺TILs in post‐treatment resected specimens was significantly increased compared with that in pretreatment biopsy samples. We concluded that T lymphocyte‐mediated immune reactions play an important role in tumor response to neoadjuvant treatment for rectal cancer, and the evaluation of TILs in pretreatment biopsy samples might be a predictor of the clinical effectiveness of neoadjuvant treatment. Furthermore, neoadjuvant therapy, especially chemoradiotherapy, could induce the activation of the local immune status.

Stereotactic Body Radiation Therapy in the Management of Upper GI Malignancies

The role of external beam radiation therapy (EBRT) in the management of upper gastrointestinal malignancies is constantly evolving. As radiation therapy techniques improve and are able to deliver more ablative doses of radiotherapy while sparing healthy tissue, radiation can be applied to a wider range of clinical scenarios. Stereotactic body radiation therapy (SBRT) allows a high dose of radiation to be delivered to a highly conformal treatment volume in a short amount of time. Another potential advantage of SBRT is its ability to increase tumor immunogenicity, while also having less of an immunosuppressive effect on the patient, as compared to conventionally fractionated radiation therapy. In so doing, SBRT may potentiate the effects of immune therapy when the two treatments are combined, thus improving therapeutic outcomes. This article provides an overview of the role of SBRT in the management of upper gastrointestinal GI malignancies and the emerging data on immune biomarkers and SBRT, with a focus on pancreatic and liver cancer.

Neoadjuvant radiochemotherapy decreases the total amount of tumor infiltrating lymphocytes, but increases the number of CD8+/Granzyme B+ (GrzB) cytotoxic T-cells in rectal cancer

Although neoadjuvant radiochemotherapy (nRCTx) is an established oncological treatment in patients with advanced rectal cancer, little is known about its effects on the tumor microenvironment. Quantity and composition of tumor infiltrating lymphocytes (TILs) are known to influence patients' prognosis but nRCTx-induced modifications are still unclear. We determined the composition of the immune cell infiltrate in rectal cancer after nRCTx and its influence on tumor regression, local recurrence rate and survival. We investigated density and composition of tumor infiltrating CD3⁺ and CD8⁺ T-cells and the quantity and ratio of CD8⁺/GrzB⁺ T-cells to CD8⁺ T-cells in 130 rectal cancers after nRCTx compared to a cohort of 30 primarily resected rectal cancers. Furthermore, we analyzed 22 pretherapeutic rectal cancer biopsies, later treated with nRCTx and surgery to evaluate nRCTx-induced modifications of the tumor microenvironment. The total numbers of CD3⁺ and CD8⁺ T-cells in tumor stroma (p < 0.001) and tumor epithelium (p < 0.001 CD3; 0.002 CD8) were significantly lower in rectal cancers after nRCTx compared to primarily resected cases, while the ratio of CD8⁺/GrzB⁺ T-cells to CD8⁺ T-cells was significantly increased in the nRCTx cohort (p < 0.001). In multivariate analyses, CD8⁺/GrzB⁺ T-cells in the tumor stroma were significantly associated with high regression grade and a lower likelihood of local recurrence (p = 0.029). nRCTx modifies the tumor microenvironment of rectal cancer leading to a total decrease of TILs, but a relative increase in CD8⁺/GrzB⁺ T-cells in the tumor stroma. CD8⁺/GrzB⁺ T-cells may contribute to local tumor control and the better outcome.

Persistent changes in circulating white blood cell populations after splenectomy

The effect of splenectomy on the incidence of infections and thromboembolisms has been investigated thoroughly. Nevertheless, the long-term effects of splenectomy on immunological profile and circulating blood counts have not been described before. To study such long-term effects, we analysed several parameters in splenectomised trauma patients and compared the results of this group ("otherwise healthy patients") to patients with a specific underlying disease. We measured platelet count, leukocytes and differential, lymphocyte subsets, serum levels of immunoglobulins, and complement pathways in 113 patients. Indications to perform a splenectomy were trauma (n = 42), Hodgkin lymphoma (n = 24), hereditary spherocytosis (n = 21), and immune thrombocytopenia (n = 26). In trauma patients lymphocytes and lymphocytes subsets were particularly elevated compared to normal population values. Splenectomised patients with Hodgkin lymphoma had significant lower numbers of T lymphocytes than trauma patients. Significant increases in platelets, leukocytes, and monocytes were observed in patients with hereditary spherocytosis. Occurrence of MBL genotype was different in ITP patients than in other splenectomised groups and the normal population. In splenectomised patients (> 4 years), platelet counts and lymphocyte subsets are increased which persist over time. As a result, these blood counts in splenectomised patients differ from reference values in the normal population.

Tumour radiosensitivity is associated with immune activation in solid tumours

PURPOSE

Our goal was to determine whether tumour radiosensitivity is associated with activation of the immune system across all tumour types as measured by two gene expression signatures (GESs).

METHODS

We identified 10,240 genomically profiled distinct solid primary tumours with gene expression analysis available from an institutional de-identified database. Two separate GESs were included in the analysis, the radiosensitivity index (RSI) GES (a 10-gene GES as a measure of radiosensitivity) and the 12-chemokine (12-CK) signature (a 12-gene GES as a measure of immune activation). We tested whether the RSI and 12-CK were associated with each other across all tumour samples and, in an exploratory analysis, their prognostic significance in predicting distant metastasis-free survival (DMFS) among a well-characterised, independent cohort of 282 early-stage breast cancer cases treated with surgery and post-operative radiation alone without systemic therapy. The lower the RSI score, the higher the tumour radiosensitivity; whereas, the higher the 12-CK score the higher the immune activation.

RESULTS

Using an RSI cut-point of ≤0.3745, RSI-low tumours (n = 4,291, 41.9%) had a significantly higher median 12-CK GES value (0.54 [-0.136, 1.095]) compared with RSI-high tumours (-0.17 [-0.82, 0.42]; p < 0.001) across all tumour samples, indicating that radiosensitivity is associated with immune activation. In an exploratory analysis of early-stage breast cancer cases, a multivariable model with patient age, RSI and 12-CK provided a strong composite model for DMFS (p = 0.02), with RSI (hazard ratio [HR] 0.63 [95% confidence interval 0.36, 1.09]) and 12-CK (HR 0.66 [0.41, 1.04]) each providing comparable contributions.

CONCLUSIONS

Tumour radiosensitivity is associated with immune activation as measured by the two GESs.

DNA Damage and Repair Biomarkers of Immunotherapy Response

DNA-damaging agents are widely used in clinical oncology and exploit deficiencies in tumor DNA repair. Given the expanding role of immune checkpoint blockade as a therapeutic strategy, the interaction of tumor DNA damage with the immune system has recently come into focus, and it is now clear that the tumor DNA repair landscape has an important role in driving response to immune checkpoint blockade. Here, we summarize the mechanisms by which DNA damage and genomic instability have been found to shape the antitumor immune response and describe clinical efforts to use DNA repair biomarkers to guide use of immune-directed therapies.Significance: Only a subset of patients respond to immune checkpoint blockade, and reliable predictive biomarkers of response are needed to guide therapy decisions. DNA repair deficiency is common among tumors, and emerging experimental and clinical evidence suggests that features of genomic instability are associated with response to immune-directed therapies. Cancer Discov; 7(7); 675-93. ©2017 AACR.

Improving radiotherapy in cancer treatment: Promises and challenges

Effective radiotherapy for cancer has relied on the promise of maximally eradicating tumor cells while minimally killing normal cells. Technological advancement has provided state-of-the-art instrumentation that enables delivery of radiotherapy with great precision to tumor lesions with substantial reduced injury to normal tissues. Moreover, better understanding of radiobiology, particularly the mechanisms of radiation sensitivity and resistance in tumor lesions and toxicity in normal tissues, has improved the treatment efficacy of radiotherapy. Previous mechanism-based studies have identified many cellular targets that can affect radiation sensitivity, notably reactive oxygen species, DNA-damaging response signals, and tumor microenvironments. Several radiation sensitizers and protectors have been developed and clinically evaluated; however, many of these results are inconclusive, indicating that improvement remains needed. In this era of personalized medicine in which patients’ genetic variations, transcriptome and proteomics, tumor metabolism and microenvironment, and tumor immunity are available. These new developments have provided opportunity for new target discovery. Several radiotherapy sensitivity-associated “gene signatures” have been reported although clinical validations are needed. Recently, several immune modifiers have been shown to associate with improved radiotherapy in preclinical models and in early clinical trials. Combination of radiotherapy and immunocheckpoint blockade has shown promising results especially in targeting metastatic tumors through abscopal response. In this article, we succinctly review recent advancements in the areas of mechanism-driven targets and exploitation of new targets from current radio-oncogenomic and radiation-immunotherapeutic approaches that bear clinical implications for improving the treatment efficacy of radiotherapy.

Radiation-related lymphopenia is associated with spleen irradiation dose during radiotherapy in patients with hepatocellular carcinoma

BACKGROUND

The decrease in peripheral blood lymphocytes induced by radiation lessens the antitumour effect of the immune response, which might cause immunosuppression. We aimed to investigate the correlation between the decrease in peripheral blood lymphocytes during radiotherapy (RT) and the spleen irradiation dose in patients with hepatocellular carcinoma (HCC).

METHODS

The subjects were 59 patients with HCC who had received RT from 2005 to 2014. The Min ALC (minimum value of absolute counts for peripheral blood lymphocytes) was collected from the routine workup for each patient prior to RT and weekly during RT. Spleen dose-volume variables, including the percentage of the organ volume receiving ≥ n Gy (Vn) and the mean spleen dose (MSD), were calculated using Eclipse treatment planning. Potential associations between dosimetric variables and the Min ALC were assessed by multiple linear regression analysis.

RESULTS

Peripheral lymphocytes decreased during RT (P < 0.001). The Min ALC correlated with the MSD (P = 0.005), spleen V5 (P = 0.001), spleen V25 (P = 0.026) and spleen V30 (P = 0.018). Controlling for the Karnofsky performance status (KPS), sex, age, Child-Pugh grade, total dose and tumour stage, a multiple linear regression model with bootstrap analysis of 1000 replicates showed that only the spleen V5 was correlated with the decrease in the Min ALC (P < 0.05). According to the receiver-operating characteristic (ROC) curve analysis, the predictive cutoff values of the MSD, V5, V25 and V30 of the spleen for the Min ALC were 227.72 cGy, 17.84, 0.98 and 0.42%, respectively (P = 0.002, P = 0.004, P = 0.007 and P = 0.002, respectively). Furthermore, an MSD ≥ 227.72 cGy (OR = 14.39; 95% CI, 12.18 to 16.60) and V5 (OR = 7.99; 95% CI, 6.91 to 9.07) of the spleen significantly predicted the Min ALC.

CONCLUSIONS

Higher spleen irradiation doses were significantly correlated with lower Min ALC during RT for HCC. V5 should be limited in clinical practice. Maximum sparing for spleen irradiation during RT is recommended to preserve peripheral blood lymphocytes, which may decrease immunosuppression.

Timing and type of immune checkpoint therapy affect the early radiographic response of melanoma brain metastases to stereotactic radiosurgery

BACKGROUND

Growing evidence suggests that immunotherapy and radiation therapy can be synergistic in the treatment of cancer. This study was performed to determine the effect of the relative timing and type of immune checkpoint therapy on the response of melanoma brain metastases (BrMets) to treatment with stereotactic radiosurgery (SRS).

METHODS

Seventy-five melanoma patients with 566 BrMets were treated with both SRS and immune checkpoint therapy between 2007 and 2015 at a single institution. Immunotherapy and radiosurgery treatment of any single lesion were considered concurrent if SRS was administered within 4 weeks of immunotherapy. The impact of the timing and type of immunotherapy on the lesional response was determined with the Wilcoxon rank-sum test, which was used to compare the median percent lesion volume change 1.5, 3, and 6 months after SRS treatment, with significance determined by P = .0167 according to the Bonferroni correction for multiple comparisons.

RESULTS

Concurrent use of immunotherapy and SRS resulted in a significantly greater median percent reduction in the lesion volume at 1.5 (-63.1% vs -43.2%, P < .0001), 3 (-83.0% vs -52.8%, P < .0001), and 6 months (-94.9% vs -66.2%, P < .0001) in comparison with nonconcurrent therapy. The median percent reduction in the lesion volume was also significantly greater for anti-programmed cell death protein 1 (anti-PD-1) than anti-cytotoxic T-lymphocyte-associated protein 4 (anti-CTLA-4) at 1.5 (-71.1% vs -48.2%, P < .0001), 3 (-89.3% vs -66.2%, P < .0001), and 6 months (-95.1% vs -75.9%, P = .0004).

CONCLUSIONS

The administration of immunotherapy within 4 weeks of SRS results in an improved lesional response of melanoma BrMets in comparison with treatment separated by longer than 4 weeks. Anti-PD-1 therapy also results in a greater lesional response than anti-CTLA-4 after SRS. Cancer 2016;122:3051-3058. © 2016 American Cancer Society.

Radiation and checkpoint blockade immunotherapy: radiosensitisation and potential mechanisms of synergy

Checkpoint blockade immunotherapy has received mainstream attention as a result of striking and durable clinical responses in some patients with metastatic disease and a reasonable response rate in many tumour types. The activity of checkpoint blockade immunotherapy is not restricted to melanoma or lung cancer, and additional indications are expected in the future, with responses already reported in renal cancer, bladder cancer, and Hodgkin's lymphoma among many others. Additionally, the interactions between radiation and the immune system have been investigated, with several studies describing the synergistic effects on local and distant tumour control when radiation therapy is combined with immunotherapy. Clinical enthusiasm for this approach is strengthened by the many ongoing trials combining immunotherapy with definitive and palliative radiation. Herein, we discuss the biological and mechanistic rationale behind combining radiation with checkpoint blockade immunotherapy, with a focus on the preclinical data supporting this potentially synergistic combination. We explore potential hypotheses and important considerations for clinical trial designs. Finally, we reintroduce the notion of radiosensitising immunotherapy, akin to radiosensitising chemotherapy, as a potential definitive therapeutic modality.

Radiation and immunotherapy: a synergistic combination

Immunotherapy can be an effective treatment for metastatic cancer, but a significant subpopulation will not respond, likely due to the lack of antigenic mutations or the immune-evasive properties of cancer. Likewise, radiation therapy (RT) is an established cancer treatment, but local failures still occur. Clinical observations suggest that RT may expand the therapeutic reach of immunotherapy. We examine the immunobiologic and clinical rationale for combining RT and immunotherapy, two modalities yet to be used in combination in routine practice. Preclinical data indicate that RT can potentiate the systemic efficacy of immunotherapy, while activation of the innate and adaptive immune system can enhance the local efficacy of RT.

Sustained long-term immune responses after in situ gene therapy combined with radiotherapy and hormonal therapy in prostate cancer patients

PURPOSE

To explore long-term immune responses after combined radio-gene-hormonal therapy.

METHODS AND MATERIALS

Thirty-three patients with prostate specific antigen 10 or higher or Gleason score of 7 or higher or clinical stage T2b to T3 were treated with gene therapy that consisted of 3 separate intraprostatic injections of AdHSV-tk on Days 0, 56, and 70. Each injection was followed by 2 weeks of valacyclovir. Intensity-modulated radiation therapy was delivered 2 days after the second AdHSV-tk injection for 7 weeks. Hormonal therapy was initiated on Day 0 and continued for 4 months or 2.3 years. Blood samples were taken before, during, and after treatment. Lymphocytes were analyzed by fluorescent antibody cell sorting (FACS).

RESULTS

Median follow-up was 26 months (range, 4-48 months). The mean percentages of DR+CD8+ T cells were increased at all timepoints up to 8 months. The mean percentages of DR+CD4+ T cells were increased later and sustained longer until 12 months. Long-term (2.3 years) use of hormonal therapy did not affect the percentage of any lymphocyte population.

CONCLUSIONS

Sustained long-term (up to 8 to 12 months) systemic T-cell responses were noted after combined radio-gene-hormonal therapy for prostate cancer. Prolonged use of hormonal therapy does not suppress this response. These results suggest the potential for sustained activation of cell-mediated immune responses against cancer.

Hydronephrosis as a prognostic factor in pelvic recurrence from rectal and colon carcinomas

BACKGROUND

After multimodal treatment estimated 5-year survival of locally recurrent rectal cancer is about 25%. Hydronephrosis secondary to pelvic recurrence of colorectal cancer is a condition claimed to represent a contraindication to surgery due to a dismal prognosis.

METHODS

Prospective registration of 193 consecutive patients operated for pelvic recurrence in rectal or colon cancer from January 1991 until March 2002 at a tertiary referral hospital, 121 men and 72 women, median age 67 years, all given irradiation preoperatively. Twenty-three of 193 had hydronephrosis prior to preoperative irradiation for recurrent disease.

RESULTS

R-0 stage resection was obtained in 22% of patients with hydronephrosis and in 41% without. The median survival times in patients without metastasis were 27 and 32 months, respectively, and 5-year survival rates were 11% and 25%.

CONCLUSIONS

An aggressive surgical approach offers patients with pelvic recurrence from rectal and colon cancer the best potential for survival. The presence of hydronephrosis probably indicates a lower chance for complete surgical resection of the recurrence, but local control and improved survival may still be achieved, and about two thirds of patients may benefit from the operation.

Enhanced systemic T-cell activation after in situ gene therapy with radiotherapy in prostate cancer patients

PURPOSE

In situ cytotoxic gene therapy can potentially trigger a systemic immune response, which could impact occult metastatic disease. We are currently conducting three clinical trials using in situ adenoviral vector mediated herpes simplex virus-thymidine kinase (HSV-tk) gene delivery followed by the HSV-tk prodrug ganciclovir (GCV) or valacyclovir (VCV). This study evaluates the systemic T-cell response after gene therapy in each trial.

METHODS AND MATERIALS

The study protocol included three separate clinical trials in the Baylor Prostate Cancer SPORE Program: Trial A gene therapy in prostate cancer patients failing radiotherapy (36 patients), Trial B neoadjuvant gene therapy in pre-radical prostatectomy patients (22 patients), and Trial C gene therapy in combination with radiotherapy for prostate cancer (27 patients). Heparinized blood was collected at the time of vector injection and at selected intervals afterward. A complete blood count was performed, and peripheral blood lymphocytes were analyzed by fluorescent antibody cell sorting after labeling with dual color-labeled antibody pairs.

RESULTS

The pretreatment mean percentage of activated CD8+ T cells (DR+CD8+ T cells) was 12.23%, 16.72%, and 14.09% (Trials A, B, and C, respectively). Two weeks posttreatment, this increased to 22.87%, 26.15%, and 39.04% (Trials A, B, and C, respectively), and these increases were statistically significant (p = 0.0188, p = 0.0010, p < 0.0001, respectively). The increase of DR+CD8+ T cells was significantly larger in Trial C than in Trial A (p = 0.0044) or Trial B (p = 0.0288). Total CD8+ T cells significantly increased at 2 weeks posttreatment in Trial B and C (p = 0.0013, p = 0.0004, respectively). Interestingly, only in Trial C were significant increases in activated CD4+ T cells seen at 2 weeks (p = 0.0035).

CONCLUSIONS

This is the first report of systemic T-cell responses after HSV-tk+GCV/VCV gene therapy under three clinical trial conditions. There was an increase in activated CD8+ T cells in the peripheral blood after vector injection, suggesting the potential for activation of components of cell-mediated immune response in all trial conditions. The addition of radiotherapy to in situ gene therapy seems to further increase the total CD8+ T cells and activated CD4+ T cells.

Therapeutic potential of mycobacterial cell wall-DNA complexes

Cell wall skeletons isolated from many bacteria have been shown to possess anticancer activity. The anticancer activities of such preparations have been attributed to the activation of immune effector cells and not to a direct effect on cancer cell division. A cell wall extract from Mycobacterium phlei, wherein mycobacterial DNA in the form of short oligonulceotides is preserved to the cell wall, has anticancer activity against a wide range of cancer cells. Mycobacterial cell wall-DNA complexes (MCC) exert their anticancer activity by a dual mechanism of action: an indirect effect via the induction of anticancer cytokines and a direct effect on cancer cell division mediated by the induction of apoptosis. In this review, the immunomodulatory and the pro-apoptotic mechanisms of action of MCC will be explored. The identification of the active component in MCC will be discussed, as well as the composition differences with cell wall skeletons and live mycobacteria. Finally, the use of MCC against bladder and prostate cancers will be discussed and compared to standard therapies, particularly therapy using mycobacteria and mycobacteria-derived products.

Non-melanoma skin cancer may be a marker of poor prognosis in patients with non-Hodgkin's lymphoma

According to recent results, patients with non-melanoma skin cancers are at increased risk of developing non-Hodgkin's lymphoma (NHL). The prognostic significance of this association is unknown. Two cohorts of patients with a first diagnosis of non-melanoma skin cancer and a subsequent diagnosis of either NHL (n = 170) or colon cancer (n = 435) were established using national cancer registry data in Denmark. Two other cohorts of patients in whom NHL (n = 600) or colon cancer (n = 1,541) was the patients' first known malignancy served as comparison groups. Mortality rates were compared using Cox's regression analysis. Among patients younger than 80 years at NHL diagnosis, a history of non-melanoma skin cancer was associated with significantly increased mortality [relative risk (RR) = 1.54; 95% confidence interval: 1.19-1.99]. This association was present in both men (RR = 1.38; 1.02-1.86) and women (RR = 2.15; 1.31-3.54) and was similar after both major subtypes of non-melanoma skin cancer. Overall, antedating non-melanoma skin cancer had no prognostic significance for colon cancer patients (RR = 1.00; 0.84-1.18). Whatever the underlying mechanism, our observation has potential clinical implications. If substantiated in other settings, NHL patients with prior non-melanoma skin cancer may constitute a subgroup of lymphoma patients in need of particular therapeutic attention.

Tracheobronchial amyloidosis. The Boston University experience from 1984 to 1999

Tracheobronchial amyloidosis (TBA), an idiopathic disorder characterized by deposition of fibrillar proteins in the tracheobronchial tree, occurred in 10 patients referred to the Amyloid Program at Boston University over the past 15 years. Fewer than 100 cases of TBA have been described; only 1 series encompassed more than 3 patients. We analyzed our experience with biopsy-proven TBA to define better its natural history. Follow-up averaged approximately 8 years and was obtained in all cases, making this outcome reporting the largest and most complete to date. Three of these patients were prospectively studied for up to 24 months to examine the utility of bronchoscopy, computerized tomography (CT) imaging, and pulmonary function tests (PFTs) in monitoring disease progression. No patient with TBA developed signs or symptoms of systemic amyloidosis during the period reviewed. Conversely, tracheobronchial disease was not diagnosed in 685 patients with primary systemic (AL) amyloidosis during the 15-year study period at Boston University. Bronchoscopy proved most useful in establishing the diagnosis by biopsy. Narrowing of major airways limited its inspection of the tracheobronchial tree, however. In contrast, CT imaging provided quantitative assessment of airway narrowing and mural thickening--2 major consequences of amyloid infiltration. These CT features, in the presence of mural calcifications sparing the posterior tracheal membrane, have been reported in few disorders other than TBA. The ability of CT to map airway involvement and identify extraluminal manifestations of TBA made it the study of choice for establishing disease extent. Three patterns of disease were evident by CT imaging and bronchoscopic examination: proximal, mid, and distal airways involvement. Those with severe proximal disease had significantly decreased air flows, air trapping, and fixed upper airway obstruction on PFTs. Patients with distal disease had normal airflows. PFTs could not clearly distinguish proximal from severe mid airways disease. Thirty percent of patients died within 7-12 years after diagnosis, all having proximal or severe mid airways disease. Repeated rigid bronchoscopic debridement and laser treatments did not prevent progressive airways narrowing in patients dying from TBA. Most patients with mid airways involvement, and all distal airway cases, had either stagnant disease or slowly increasing amyloid deposits when followed for up to 14 years. In a small subset of patients followed prospectively, serial PFTs were most sensitive to disease progression. CT-derived measures of airway lumen diameter and wall thickness did not change significantly despite marked improvements in airflow after rigid bronchoscopy. Our experience suggests that serial PFTs and CT imaging together offer the best assessment of airway involvement and disease progression in patients with TBA. In the future, radiation therapy may provide more definitive treatment of TBA than debulking procedure have to date.

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.

Half-body radiotherapy in the treatment of canine lymphoma

In a Phase I-II study, half-body radiotherapy was used to treat 14 dogs with multicentric lymphoma. Using this technique, a radiation dose of 7 Gray (Gy) was delivered to one half of the body in a single exposure. The other half of the body was treated approximately 28 days later. Of 14 treated dogs, 11 (79%) had a measurable decrease in tumor size. Five dogs achieved a complete or partial remission with a mean duration of 102 and 54 days, respectively. In predicting response to therapy, poor prognostic factors included large tumor burdens, advanced disease stage, and chemotherapy-resistant tumors. Side effects of treatment were divided chronologically into acute (radiation sickness, tumor lysis), subacute (bone marrow suppression), and chronic (radiation pneumonitis, lymphoma-cell leukemia) syndromes. Complications were more severe in tumor-bearing dogs when compared with healthy control animals. Dogs with small tumor burdens and minimal internal disease had fewer complications compared with those with more advanced disease.

Low-dose-rate total lymphoid irradiation: a new method of rapid immunosuppression

Total Lymphoid Irradiation (TLI) has been successful in inducing immunosuppression in experimental and clinical applications. However, both the experimental and clinical utility of TLI are hampered by the prolonged treatment courses required (23 days in rats and 30-60 days in humans). Low-dose-rate TLI has the potential of reducing overall treatment time while achieving comparable immunosuppression. This study examines the immunosuppressive activity and treatment toxicity of conventional-dose-rate (23 days) vs low-dose-rate (2-7 days) TLI. Seven groups of Lewis rats were given TLI with 60Co. One group was treated at conventional-dose-rates (80-110 cGy/min) and received 3400 cGy in 17 fractions over 23 days. Six groups were treated at low-dose-rate (7 cGy/min) and received total doses of 800, 1200, 1800, 2400, 3000, and 3400 cGy over 2-7 days. Rats treated at conventional-dose-rates over 23 days and at low-dose-rate over 2-7 days tolerated radiation with minimal toxicity. The level of immunosuppression was tested using allogeneic (Brown-Norway) skin graft survival. Control animals retained allogeneic skin grafts for a mean of 14 days (range 8-21 days). Conventional-dose-rate treated animals (3400 cGy in 23 days) kept their grafts 60 days (range 50-66 days) (p less than .001). Low-dose-rate treated rats (800 to 3400 cGy total dose over 2-7 days) also had prolongation of allogeneic graft survival times following TLI with a dose-response curve established. The graft survival time for the 3400 cGy low-dose-rate group (66 days, range 52-78 days) was not significantly different from the 3400 cGy conventional-dose-rate group (p less than 0.10). When the total dose given was equivalent, low-dose-rate TLI demonstrated an advantage of reduced overall treatment time compared to conventional-dose-rate TLI (7 days vs. 23 days) with no increase in toxicity. This was accomplished without compromise of the immunosuppressant activity of TLI as demonstrated by comparable allogeneic skin graft survival times between the two 3400 cGy treatment groups. This clinical advantage would prove to be beneficial where immediate suppression of the immune system is desirable.

Cardiovascular and metabolic response of tumour-bearing dogs to whole body hyperthermia

Whole body hyperthermia was induced in older, tumour-bearing dogs using a radiant heat device. Dogs were anaesthetized (thiopental), paralysed (atracurium), and mechanically ventilated (100 per cent O2) during the heating procedure. Heart rate, systolic/diastolic, and mean arterial blood pressure, and arterial blood gases were monitored throughout the procedure. Serum biochemical parameters, complete blood count, and coagulation profiles were evaluated before, during, and after whole body hyperthermia. Significant increases (p less than 0.05) were noted in heart rate, systolic pressure, diastolic pressure, and mean arterial pressure during the treatment period. A significant decrease in arterial oxygen partial pressure due to unknown causes occurred during the treatment period. Clinical evidence of cardiac decompensation was not manifested in any dog following whole body hyperthermia. Total white blood cell count, neutrophil count, alkaline phosphatase, and creatinine kinase were significantly (p less than 0.05) increased 24 h following whole body hyperthermia. These elevations returned to normal within 1 week of treatment in all dogs. Changes in coagulation profiles 24 h following the procedure were not clinically significant. Adequate pretreatment evaluation of cardiovascular, metabolic, and haemostatic function in tumour-bearing dogs is necessary to identify candidates for treatment with systemic hyperthermia. Otherwise healthy, tumour-bearing dogs withstand the physiological stress of whole body hyperthermia without significant acute or persistent toxicity and represent a valuable model for whole body hyperthermia research.

Hypogammaglobulinemia and hemophagocytic syndrome associated with lymphoproliferative disorders

Four patients with lymphohistiocytic disorders had or subsequently experienced severe hypogammaglobulinemia and pancytopenia due to hemophagocytosis. The percentages of B- and T-lymphocytes and the ratios of helper (OKT4) cells to suppressor (OKT8) cells in the peripheral blood were variably altered. Mitogenic response to pokeweed mitogen and phytohemagglutinin was depressed but could be restored to near normal by the in vitro addition of indomethacin or interleukin-2. The half-life of intravenously administered immunoglobulin was markedly shortened. The data indicate that hyperactive monocytes/histiocytes are capable of simultaneously ingesting apparently normal blood cells and immunoglobulin, leading to pancytopenia and hypogammaglobulinemia. The monocytes with suppressor activity (which could be abrogated with indomethacin or interleukin-2) appeared to additionally contribute to the hypogammaglobulinemia, possibly by interfering with the terminal differentiation of the B-lymphocytes. Hemophagocytosis occurs frequently in histiocytic and occasionally in lymphoproliferative disorders or viral diseases. More frequent and serial determination of serum immunoglobulin levels in such situations may lead to the discovery of additional cases.

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

The effects of mediastinal irradiation (RT) on the numbers and functions of purified peripheral blood T-lymphocytes from patients with locally advanced non-small cell lung cancer were evaluated. The patients were candidates for a randomized trial to evaluate the immunorestorative properties of synthetic thymosin alpha-1. Twenty-one patients studied before RT did not exhibit any significant difference in T-cell numbers or function compared to age-matched healthy subjects. However, 41 patients studied within 1 week after completing RT exhibited significant depressions of E-rosette-forming cells at 4 degrees C (E4 degrees-RFC)/mm3, E-rosette-forming cells at 29 degrees C (E29 degrees-RFC)/mm3, OKT3/mm3, OKT4/mm3, and OKT8/mm3 (P = 0.0001); total T-cell percentages (%OKT3, P = 0.01); and T-cell proliferative responses in mixed lymphocyte cultures (MLR) (P = 0.01) and to the mitogen phytohemagglutinin under suboptimal conditions (P less than or equal to 0.03). Nine patients studied before and after RT showed a significant increase in OKT4/OKT8 (P = 0.01) following RT. A short-term in vitro incubation with thymosin alpha-1 could enhance MLR of T-cells in 12 of 27 patients with post-RT abnormalities. In 13 patients who were treated with placebo, the RT-induced depression of T-cell numbers and function persisted for at least 3 to 4 months. In addition, in 12 patients progressive decreases developed in %E4 degrees-RFC, %OKT3, %OKT4, and OKT4/OKT8, which always preceded clinical relapse. This study indicates that mediastinal RT results in prolonged depletion of circulating T-cells, alterations of T-cell subset proportions, and intrinsic T-cell functional deficiencies. This patient population provides a uniformly immunosuppressed group of subjects with which to evaluate the immunorestorative effects of thymosin alpha-1 or other biologic response modifiers.

A serum inhibitor of neutrophil chemotaxis associated with hyperglobulinaemia E in a patient with lymphoma, and recurrent skin infection

A patient with a strong serum inhibitor of neutrophil chemotaxis, a possible chemotactic factor inactivator and hyperimmunoglobulinaemia E is described. The patient had a persistent chronic dermatitis which appeared to develop following radiation of the central nervous system for an unclassified lymphoma. Other abnormalities included a general increase of serum immunoglobulins, impaired lymphocyte response to mitogens, and a high Epstein-Barr antibody titre. This case illustrates that an increased IgE level, previously reported in association with a cellular chemotactic defect, may coexist with serum inhibitors of neutrophil chemotaxis.

Depressed in vitro lymphoproliferation after radiation therapy. Influences of adherent cells, indomethacin, and autologous serum

Mixed lymphocyte culture (MLC) responses and lymphocyte proliferative responses to phytohaemagglutinin (PHA) stimulation were determined before and after pelvic irradiation with 40 Gy in 10 patients with endometrial carcinoma stage I. The MLC responses were depressed after irradiation, and were not normalized after adherent cell depletion. Adherent cells did not significantly suppress the responses of non-adherent lymphocytes. Indomethacin could not restore the depressed PHA responses occurring after irradiation. Autologous posttreatment serum was not suppressive. The results favour the assumption that irradiation causes immunodepression by injuring the responding cells or some amplifier system, rather than by activation of suppressor systems.

Immunological monitoring of patients affected by anaplastic glioma concerning in effects of surgery, radio-, and chemotherapy. A preliminary report

The authors studied 24 patients affected by anaplastic gliomas, as regards immunology. In all of them the authors evaluated the lymphocyte subpopulation (B and T), firstly by simple lymphocyte count, secondly by studying the rosettes E-total and EAC, thirdly by stimulating the lymphocytes with mitogens phyto-haemoagglutinin-P (PHA), concanavalin A (Con A), and pokeweed mitogen (PWM), and lastly by counting the release of Cr51 in Chang liver cells culture in order to obtain antibody dependent cellular cytotoxicity (ADCC). The parameters were also evaluated after surgery and during conventional radio-chemotherapy with BCNU. Whereas the so-called B-pool seems to be unaffected, the preliminary results show that the T-pool (identified by the E-t rosettes and by responses to PHA, PWM, and ConA) is depressed to a statistically significant degree, if compared with a control group. This depression seems to be related to the tumoral mass, and it is not increased by radio-chemotherapy. In addition, ADCC also seems to be depressed in our glioma patients in comparison with a control group and witha group of bladder cancer patients.

Longitudinal studies of blood lymphocyte capacity in Hodgkin's disease

Blood lymphocyte functional capacity and serum immunoglobulins were studied in 40 patients with Hodgkin's disease (HD) admitted to Radiumhemmet, Stockholm, before treatment and in complete remission 2-56 months following termination of radiotherapy (total nodal irradiation [TNI]; n = 29) or chemotherapy (MOPP; n = 11). Lymphocyte studies included determination of total lymphocyte and T-cell counts and evaluation of spontaneous DNA synthesis during the first day of culture and mitogen-(concanavalin A, pokeweed mitogen) and antigen (purified protein derivative, PPD)-induced activation on the third day. Blood lymphocyte and T-cell counts decreased dramatically following TNI. A slow restitution was seen, but pretreatment levels were not reached even four years following therapy. The responses to ConA and PPD but not PWM were significantly reduced shortly after TNI. The mitogen response did not increase with time as did the PPD response. Lymphocyte counts and lymphocyte stimulation, which were severely depressed before treatment of patients in the chemotherapy group, remained unchanged 2-36 months after termination of therapy. A significant reduction of IgM levels was observed regardless of the mode of treatment. Splenectomy prevented the profound reduction of blood lymphocyte and T-cell counts following therapy but did not influence the other immunologic variables under study.

Effects of washing on phytohemagglutinin responsiveness of lymphocytes from irradiated patients

The peripheral lymphocytes from irradiated patients generally have a reduced capability to respond to phytohemagglutinin (PHA). Whether a relationship exists between PHA-responsiveness and chromosome aberration frequencies was examined by washing the lymphocytes with culture medium. The results indicate that the defect in lymphocyte activation in patients receiving radiation therapy was caused by some reversible changes in the lymphocyte membrane directly associated with radiation exposure rather than by a radiation induced suppressor substance secondarily acting on the lymphocyte membrane.

Immunoblastic lymphosarcoma: a light, immunofluorescence, and electron microscopic study

Immunoblastic lymphosarcoma (ILS) is a newly recognized malignant lymphoreticular neoplasm and is included in the recent W.H.O. classification of lymphomas. This report concerns six cases of ILS studied by light, immunofluorescence (IF), and electron microscopy (EM). Four patients were female and all except one were over 50 years of age. Four patients had some immunological abnormality. Light microscopy showed a monomorphic population of immunoblasts with pyroninophilic cytoplasm and variable plasmacytoid differentiation. Intracytoplasmic IgG was demonstrated by IF in four cases, and IgA in one. Large lymphoid cells with varying proportions of polysomes, rough endoplasmic reticulum, and Golgi apparatus were seen by EM in four cases. Mean survival was 4.8 months in five cases; death in four was due to disseminated ILS. We concluded that our cases of ILS are of B cell origin, are often associated with immunological abnormalities, and carry a poor prognosis. Immunofluorescence and EM are helpful in its diagnosis.

Improvement of in vitro mitogen proliferative responses in non-Hodgkin's lymphoma patients exposed to fractionated total body irradiation

Patients with non-Hodgkin's lymphomas who failed to respond to chemotherapy were treated with low dose fractionated total body irradiation (TBI). Prior to during and after scheduled therapy, their clinical status was evaluated and peripheral blood studies were performed to enumerate EAC and E rosetting cells and to measure proliferative responses to mitogens. Peripheral blood abnormalities were present prior to TBI using these in vitro assays. Patients who obtained clinical remissions following therapy had restoration of mitogen progressive disease had no change in their ability to proliferate in response to mitogens. Normalization of EAC and E rosetting profiles often occurred regardless of clinical response. These data indicate that low dose fractionated TBI produces clinical and in vitro detectable immunological changes. Furthermore, they show that improvement in mitogen responsiveness correlates best with good clinical responses.