In vitro potentiation of radiation cytotoxicity by recombinant interferons in cervical cancer cell lines

Antiviral Responses in Cancer: Boosting Antitumor Immunity Through Activation of Interferon Pathway in the Tumor Microenvironment

In recent years, it became apparent that cancers either associated with viral infections or aberrantly expressing endogenous retroviral elements (EREs) are more immunogenic, exhibiting an intense intra-tumor immune cell infiltration characterized by a robust cytolytic apparatus. On the other hand, epigenetic regulation of EREs is crucial to maintain steady-state conditions and cell homeostasis. In line with this, epigenetic disruptions within steady-state cells can lead to cancer development and trigger the release of EREs into the cytoplasmic compartment. As such, detection of viral molecules by intracellular innate immune sensors leads to the production of type I and type III interferons that act to induce an antiviral state, thus restraining viral replication. This knowledge has recently gained momentum due to the possibility of triggering intratumoral activation of interferon responses, which could be used as an adjuvant to elicit strong anti-tumor immune responses that ultimately lead to a cascade of cytokine production. Accordingly, several therapeutic approaches are currently being tested using this rationale to improve responses to cancer immunotherapies. In this review, we discuss the immune mechanisms operating in viral infections, show evidence that exogenous viruses and endogenous retroviruses in cancer may enhance tumor immunogenicity, dissect the epigenetic control of EREs, and point to interferon pathway activation in the tumor milieu as a promising molecular predictive marker and immunotherapy target. Finally, we briefly discuss current strategies to modulate these responses within tumor tissues, including the clinical use of innate immune receptor agonists and DNA demethylating agents.

Bridging Radiotherapy to Immunotherapy: The IFN-JAK-STAT Axis

The unprecedented successes of immunotherapies (IOs) including immune checkpoint blockers (ICBs) and adoptive T-cell therapy (ACT) in patients with late-stage cancer provide proof-of-principle evidence that harnessing the immune system, in particular T cells, can be an effective approach to eradicate cancer. This instills strong interests in understanding the immunomodulatory effects of radiotherapy (RT), an area that was actually investigated more than a century ago but had been largely ignored for many decades. With the "newly" discovered immunogenic responses from RT, numerous endeavors have been undertaken to combine RT with IOs, in order to bolster anti-tumor immunity. However, the underlying mechanisms are not well defined, which is a subject of much investigation. We therefore conducted a systematic literature search on the molecular underpinnings of RT-induced immunomodulation and IOs, which identified the IFN-JAK-STAT pathway as a major regulator. Our further analysis of relevant studies revealed that the signaling strength and duration of this pathway in response to RT and IOs may determine eventual immunological outcomes. We propose that strategic targeting of this axis can boost the immunostimulatory effects of RT and radiosensitizing effects of IOs, thereby promoting the efficacy of combination therapy of RT and IOs.

Combining Radiation Therapy With Interferons: Back to the Future

Radiation therapy has been linked to the induction of an intratumoral type I interferon (IFN) response, which positively affects the response to treatment. This has spiked the interest to combine radiation therapy with IFN-based treatment. Interestingly, this combination treatment has been considered previously, since preclinical studies demonstrated a radiosensitizing effect of interferons. As a result, multiple clinical trials have been performed combining radiation therapy with interferons in different tumor types. Although potential benefit has been suggested, the outcomes of the trials are diverse and challenging to interpret. In addition, increased grade ≥3 toxicity frequently resulted in a negative recommendation regarding the combination therapy. The latter appears premature because many studies were small and several aspects of the combination treatment have not yet been sufficiently explored to justify such a definite conclusion. This review summarizes the available literature on this combination therapy, with a focus on IFN-α and IFN-β. Based on preclinical studies and clinical trials, we evaluated the potential opportunities and describe the current challenges. In addition, we identify several issues that should be addressed to fully exploit the potential benefit of this combinatorial treatment approach.

Interferons α and β in cancer: therapeutic opportunities from new insights

Over the past decade, preclinical and clinical research have confirmed the essential role of interferons for effective host immunological responses to malignant cells. Type I interferons (IFNα and IFNβ) directly regulate transcription of >100 downstream genes, which results in a myriad of direct (on cancer cells) and indirect (through immune effector cells and vasculature) effects on the tumour. New insights into endogenous and exogenous activation of type I interferons in the tumour and its microenvironment have given impetus to drug discovery and patient evaluation of interferon-directed strategies. When combined with prior observations or with other effective modalities for cancer treatment, modulation of the interferon system could contribute to further reductions in cancer morbidity and mortality. This Review discusses new interferon-directed therapeutic opportunities, ranging from cyclic dinucleotides to genome methylation inhibitors, angiogenesis inhibitors, chemoradiation, complexes with neoantigen-targeted monoclonal antibodies, combinations with other emerging therapeutic interventions and associations of interferon-stimulated gene expression with patient prognosis - all of which are strategies that have or will soon enter translational clinical evaluation.

Effectiveness of Interferon-Beta Therapy for Recurrent Glioblastoma: A Case Report

Aims and background

Glioblastoma has a poor prognosis, with few therapeutic options if it recurs. We report a case in which we were able to inhibit the growth of a recurrent glioblastoma by weekly single-dose administration of interferon-beta.

Case report

A patient with recurrent glioblastoma after radiation and chemotherapy was treated with nimustine and interferon-beta. After 2 cycles of nimustine, the patient's leukocyte, neutrophil, and platelet counts showed grade 4 toxicity according to the National Cancer Institute's Common Toxicity Criteria. The patient was treated with a weekly single dose of interferon-beta at 6 × 106 IU. The tumor showed no remarkable changes after 18 months, and the patient's Karnofsky performance status remained at 50%.

Conclusions

The administration of interferon-beta produced long-term control in one case of glioblastoma and may be an effective therapy. Free full text available at www.tumorionline.it

[Identification and isolation of cancer stem cells from A549 cells]

背景与目的

肺癌干细胞是肺癌恶性表型的根源和潜在的治疗靶点，从人肺癌A549细胞株中分离肺癌干细胞，观察特异性干细胞标志物分子的表达，为进一步的干细胞研究提供试验基础。

方法

接种肺癌A549细胞株，经流式细胞术，特异性筛选分离肺癌干细胞，观察克隆形成能力、细胞增殖能力和体外致瘤能力的差别，并分别用RT-PCR和Western blot的方法分析干细胞标志物分子CD133和ABCG2的表达。

结果

经过流式细胞仪成功分选了人肺腺癌A549细胞系SP细胞亚群，结果表明此SP细胞亚群约占A549细胞总数的5.93%，经维拉帕米处理后Hoechest33342阴性/弱阳性细胞含量下降为0.32%，SP细胞克隆形成能力，细胞增殖能力和体外致瘤能力均明显高于非SP细胞。RT-PCR和Western blot结果发现，筛选分离的肺癌SP细胞群高表达干细胞标志物分子CD133和ABCG2。

结论

通过流式细胞术可以筛选分离高表达CD133和ABCG2分子的肺癌干细胞，可用于进一步的研究中。

Does adjuvant alpha-interferon improve outcome when combined with total skin irradiation for mycosis fungoides?

BACKGROUND

Patients with mycosis fungoides (MF) experience frequent disease recurrences following total skin electron irradiation (TSEI) and may benefit from adjuvant therapy.

OBJECTIVES

To review the McGill experience with adjuvant alpha-interferon (IFN) in the treatment of MF.

METHODS

From 1990 to 2000, 50 patients with MF were treated with TSEI: 31 with TSEI alone and 19 with TSEI + IFN. Median TSEI dose was 35 Gy. In the TSEI + IFN group, IFN was given subcutaneously at 3 x 10(6) units three times per week starting 2 weeks prior to start of TSEI, continued concurrently with the radiation and for an additional 12 months following TSEI. The TSEI alone group included 16 men and 15 women with a median age of 61 years (range 31-84). The TSEI + IFN group included 14 men and five women with a median age of 51 years (range 24-83). Clinical stage was IA, IB, IIA, IIB, III and IVA in 2, 9, 4, 8, 1 and 7 patients of the TSEI group and 0, 3, 3, 7, 4 and 2 patients of the TSEI + IFN group.

RESULTS

Median follow up for living patients was 70 months. All patients responded to treatment. Complete response (CR) rate was 65% following TSEI and 58% following TSEI + IFN (P = 0.6). Median overall survival (OS) was 61 months following TSEI and 38 months following TSEI + IFN (P = 0.4). Acute grade II-III dermatitis was seen in all patients. Fever, chills or myalgia were seen in 32% of patients treated with TSEI + IFN.

CONCLUSIONS

Concurrent IFN and TSEI is feasible, with acceptable toxicity. Even when controlling for disease stage, the addition of IFN did not appear to increase CR rate, disease-free survival or OS.

Angiogenesis in gynecological oncology-mechanism of tumor progression and therapeutic targets

The purpose of this article is to review the current literature pertaining to various angiogenic stimulators and angiogenesis inhibitors in gynecological malignancies and the relevance of these markers in the prognosis of these diseases. We also summarize the antiangiogenic drugs currently in development and in clinical use in gynecological oncology. The information was obtained from a computer search of MEDLINE for studies published in the English language regarding angiogenesis and angiogenesis inhibitors in gynecological malignancies between 1970 and December 2003; additional sources were identified through cross-referencing. In ovarian cancer, various different angiogenic activators have been found to correlate with microvessed density (MVD), stage, lymph node and peritoneal metastasis, and survival. In cervical cancer, correlation has been seen between increased angiogenic markers and stage, grade, tumor size, and survival. Studies in endometriat cancer show correlation of angiogenic markers with stage, grade, MVD, and survival. Whereas, in gestational trophoblastic neoplasm (GTD) only few markers have been studied, and some correlated with progression. Information on anti angiogenic drugs currently in ongoing and upcoming trials in gynecological malignancies is also presented. Angiogenesis factors may have a prognostic role to play in patients with gynecological cancers and should continue to be investigated as clinically useful tumor markers. Antiangiogenic-targeted therapies offer an attractive strategy for clinical investigation in gynecologic oncology.

Concurrent adjuvant radiotherapy and interferon-α2b for resected high risk stage III melanoma – a retrospective single centre study

Interferon-alpha2b (IFNalpha2b) is the only form of systemic adjuvant therapy for stage III melanoma with documented survival benefit. Radiotherapy can also be utilized in the adjuvant setting in patients at high risk of nodal basin recurrence. As IFNalpha2b is associated with substantial toxicity, we sought to determine both the systemic and radiation-related toxicities in patients treated with combined adjuvant IFNalpha2b and regional adjuvant radiotherapy delivered in the setting of a single institution. Eighteen consecutive patients who commenced adjuvant IFNalpha2b between November 1997 and August 2002 were analysed retrospectively for toxicities associated with the combination of IFNalpha2b and adjuvant radiotherapy (40-50 Gy in 15-25 fractions) to nodal basins delivered during the maintenance phase of IFNalpha2b therapy (median dose during radiotherapy of 6.5 MU/m three times per week). Seven out of 18 patients who received concurrent radiotherapy and IFNalpha2b displayed grade 3 skin reactions. Severe radiation-induced toxicity was seen in three further patients, one who developed radiation pneumonitis, one who developed severe oral mucositis, and one who developed wound dehiscence that took 10 months to resolve. Non-radiation-related toxicity to IFNalpha2b therapy was typical for this dose and schedule. We conclude that concurrent use of adjuvant radiotherapy and IFNalpha2b may enhance radiation-induced toxicity. However, overall we found concurrent radiation and IFNalpha2b could be safely delivered with appropriate clinical monitoring.

Phase III randomized pilot study comparing interferon alpha-2b in combination with radiation therapy versus radiation therapy alone in patients with stage III-B carcinoma of the cervix

This randomized pilot study was designed to determine whether the addition of interferon alpha-2b to standard radiation therapy offered an advantage in loco-regional control and survival over radiation therapy alone in a homogeneous group of patients with stage IIIB carcinoma of the cervix. Thirty-six patients were treated with a combination of interferon alpha-2b plus radiation therapy, and 38 patients were treated with radiation therapy alone. Patients with evidence of ureteral obstruction were excluded from the study. Evaluation of loco-regional response was determined by pelvic examination, cervical cytology, biopsies and CT scans when indicated. Survival time was measured from initiation of treatment to date of death or last follow-up. Patient characteristics were comparable between both study arms. The objective complete response rate was 67% in the combined therapy group and 55% in the radiation alone group (P = 0.454). With a median follow-up of 17 months for all patients and 31 months for live patients, 50% of the combined group survived vs. 39.5% of the radiation alone group (P = 0.424). We conclude that the addition of interferon alpha-2b to standard radiation therapy did not significantly improve loco-regional response or survival, although such a trend was noted. We encourage the design of a larger randomized study with sufficient power to detect meaningful differences to prove whether the tendency observed in the present investigation holds any promise to improve the outcome of these patients.

Towards in-vitro prediction of an in-vivo cytostatic response of human tumor cells with a fast chemosensitivity assay

The objective of this study is to evaluate a novel approach to chemosensitivity testing with respect to its predictive value in the selection of clinically effective cytostatic drugs to optimize the therapeutic treatment of cancer. The chemosensitivity assay, which we used in this study, has its roots in pharmaceutical drug screening and the surrounding intellectual property is protected by various patent applications and trademarks. Therefore, we will refer to this test in the following pages as ChemoSelect. ChemoSelect is a sensor-chip based diagnostic test, which permits the functional and continuous real-time measurement of induced tumor cell cytotoxicity following the administration of chemotherapeutic drugs. Chemosensitivity is measured through the reduction of the excretion of lactic and carbonic acids--by-products of the metabolic processes of glycolysis and respiration and a parameter for cell vitality--generated specifically by ATP hydrolysis and lactic acid production. We used this test to study the applicability of this assay for tumor cells based on the analysis of tumor cell lines and tumor specimens. In this preliminary study, this test was studied in predicting chemoresistance and chemosensitivity in cell lines and tumor specimens for which the result was already predetermined by the properties of the cell line or the tumor specimen used in the experiment. The applicability in a clinical setting was studied by confirming the trends on selected drug sensitivity and drug resistance with an interim analysis of an ongoing clinical study in selected patients with breast cancer undergoing neoadjuvant chemotherapy. The minimum detection limit of cells and biologic cell responses, an important variable determining the applicability of the test in routine clinical use, was also assessed. ChemoSelect avoids many of the limitations of existing chemoresistance assays and provides more comprehensive information and output, as it has a 24-h turnaround time, is applicable to the majority of solid tumors and available cytostatic drugs, does not need more than 10(5) cells in total, cultivated tumor cells, provides dynamic monitoring of cellular responses through on-line data read-out during the perfusion with drugs and can be extended to the analysis of novel therapeutic modalities such as biologics.

Interferon-alpha combined with radiotherapy in the treatment of unresectable melanoma

A case of recurrent and twice resected sinonasal melanoma is presented. The large recurrent tumor was found to regress by a concurrent combination of 6660 cGy photon radiation and subcutaneous interferon-alpha injections given for a period of 8 weeks. Possible mechanisms of potentiation between interferon and radiation are discussed. The unexpected result in this case report raises interesting questions about this treatment combination.

Granulocyte colony-stimulating factor (G-CSF) receptor gene expression of ovarian carcinoma does not correlate with G-CSF caused cell proliferation

BACKGROUND

Recombinant human granulocyte colony-stimulating factor (rhG-CSF) is a growth factor commonly used to avoid leukopenia after chemotherapy. Endogenous G-CSF is produced by macrophages and granulocytes that infiltrate tumors. It has been reported that rhG-CSF stimulates the proliferation of several cell lines as well as bladder carcinoma cells. Conversely, in some hematopoietic cell lines such as U-937, WEHI-3B, and K-562 no effect or in some cases a differentiation pattern was found. Moreover, the role of rhG-CSF on the proliferation of solid tumors is not well understood.

METHODS

In this study, 10 ovarian carcinoma biopsies were characterized for the presence of G-CSF and G-CSF receptor by reverse transcription-polymerase chain reaction (RT-PCR) and immunohistochemical analysis. Proliferation was analyzed by ATP viability assays.

RESULTS

Performing RT-PCR, these biopsies and four ovarian carcinoma cell lines were analyzed for endogenous G-CSF production, which was found in some biopsies and in all cell lines. Despite the presence of the G-CSF receptor in all biopsies and cell lines, no proliferation was found after rhG-CSF incubation of the cell lines or the tumor samples for 3 and for 6 days, respectively.

CONCLUSIONS

Summarizing the authors' in vitro studies, rhG-CSF does not affect the proliferation of ovarian carcinoma cells in vitro.

Radiation sensitivity of human squamous cell carcinoma cells in vitro is modulated by all-trans and 13-cis-retinoic acid in combination with interferon-alpha

PURPOSE

Retinoids and interferon-alpha (IFN-alpha) have been shown to exert antiproliferative and radiosensitizing effects. The present study was designed to determine differential effects of retinoids in combination with IFN-alpha on radiation toxicity of 5 human squamous cell carcinoma (SCC) cell lines.

METHODS AND MATERIALS

Using clonogenic assays, the effects of all-trans (ATRA), 13-cis-retinoic acid (13cRA), and IFN-alpha on radiation toxicity were analyzed. Basal mRNA expression of the cytoplasmic retinoic acid binding protein, CRABP I, was determined in retinoid-sensitive and -insensitive cell lines by reverse transcriptase/polymerase chain reaction (RT-PCR).

RESULTS

Treatment with ATRA, 13cRA, or IFN-alpha resulted in a cell line-specific inhibition of clonogenic survival. A comparison of retinoid-sensitive and insensitive cells revealed that retinoid sensitivity seems to be dependent on the basal expression level of CRABP I. ATRA, 13cRA, and IFN-alpha alone or in combination altered radiation sensitivity by affecting predominantly the alpha-component of the linear-quadratic dose-response curve. Likewise, depending upon the treatment condition the surviving fraction at 2 Gy (SF2) was decreased cell line-specifically. Combined treatment with ATRA or 13cRA and IFN-alpha markedly enhanced radiation cytotoxicity.

CONCLUSION

These in vitro data indicate that the combined treatment with retinoids, IFN-alpha, and ionizing radiation could be beneficial for patients presenting with SCC.

Combination of radiation therapy and interferon alpha-2b in patients with advanced cervical carcinoma: a pilot study

Carcinoma of the uterine cervix is the most frequent malignancy in women in developing countries. Based on the possible synergistic effect of the combination of interferon and radiotherapy, a clinical trial was conducted in patients with advanced cervical cancer. The objective was to evaluate the efficacy and security of such a therapeutic approach. This prospective phase II trial was done at the Instituto Nacional de Cancerología in Mexico City. The study included 17 consecutive patients with previously untreated squamous cell cervical cancer, clinical stages III and IV, and tumor mean size of 9.7 cm. The patients received radiotherapy and interferon alpha-2b at a dose of 5 x 106 IU/m2 3 times a week for 6 weeks. Eleven (64%) complete responses were obtained among these patients. Long-term survival was observed in 4 patients (24%) who achieved complete response and are alive after 10 years of follow-up. Immediate toxicity was mild. Late toxicity included the development of proctitis in 13 patients, colostomy was performed in 3 (23%) of them. Our results indicate that the combination of radiotherapy and this cytokine is an active therapy for squamous cell carcinoma of the uterine cervix.

The combined effect of interferon beta and radiation on five human tumor cell lines and embryonal lung fibroblasts

PURPOSE

The combined effect of natural Interferon-beta (n-IFN-beta) and ionizing radiation was tested in vitro on 5 different tumor cell lines and 1 embryonal lung fibroblast cell line.

MATERIALS AND METHODS

The following cell lines were used: A549 (lung cancer), MCF-7 (breast cancer), CaSki (cervical cancer), WiDr (colon cancer), ZMK-1 (head and neck cancer), and MRC-5 (embryonal lung fibroblast line). Cells were incubated with n-IFN-beta (30 I.U./ml to 3000 I.U./ml) 24 h before irradiation. Irradiation was given as single dose between 1 and 6 Gy. Cell survival was evaluated using a standard colony-forming assay.

RESULTS

Incubation with n-IFN-beta enhanced the effect of radiation in all tumor cell lines tested. The maximum sensitizing enhancement ratios (SER) at the 37% survival level were: 1.66 for A549 cells, 1.47 for CaSki cells, 1.56 for MCF-7 cells, 1.40 for WiDr cells, and 1.57 for ZMK-1 cells. In the nonneoplastic MRC-5 cell line, no radiosensitizing effect of n-IFN-beta could be demonstrated. The linear quadratic fit of the survival curves showed an increase of the alpha-component for all tumor cell lines treated with n-IFN-beta.

CONCLUSIONS

IFN-beta enhanced the effect of radiation in the tumor cell lines, but not in the nonmalignant lung fibroblasts. The increase of the alpha component in the survival curves indicates that impaired radiation repair or the accumulation of sublethal damage might play a role for the radiosensitizing effect of n-IFN-beta.

A 2-week pretreatment with 13-cis-retinoic acid + interferon-alpha-2a prior to definitive radiation improves tumor tissue oxygenation in cervical cancers

BACKGROUND

We have evaluated the tumor tissue pO2 in cervical cancers in patients treated with 13-cis-retinoic acid and interferon-alpha-2a prior to and during radiotherapy.

PATIENTS AND METHODS

From June 1995 through April 1997, 22 patients with squamous cell carcinoma FIGO IIB/III of the cervix who were scheduled for definitive radiotherapy with curative intent received additional treatment with 13-cis-retinoic acid (cRA, isotretinoin) plus interferon-alpha-2a (IFN-alpha-2a) as part of a phase-II protocol. cRA/IFN-alpha-2a started 14 days prior to radiotherapy (1 mg per kilogramme body weight cRA orally daily plus 6 x 10(6) IU IFN-alpha-2a subcutaneously daily). After this induction period, standard radiotherapy was administered (external irradiation with 50.4 Gy in 28 fractions of 1.8 Gy plus HDR-brachytherapy). During radiotherapy, cRA/IFN-alpha-2a treatment was continued with 50% of the daily doses. Tumor tissue pO2-measurements were performed prior to and after the cRA/IFN-induction period as well as at 20 Gy and at the end of radiotherapy with an Eppendorf-pO2-histograph.

RESULTS

In 11 out of the 22 patients, pO2-measurements were performed prior to the cRA/IFN-induction therapy. The median pO2 of these untreated tumors was 17.7 +/- 16.3 mm Hg. The relative frequency of hypoxic readings with pO2-values below 5 mm Hg ranged from 0% to 60.6% (mean 24.3 +/- 21.0%). After the 2-week induction period with cRA/IFN, the median pO2 had increased from 17.7 +/- 16.3 mm Hg to 27.6 +/- 19.1 mm Hg (not significant). In all 5 patients with hypoxic tumors prior to cRA/IFN (median pO2 of 10 mm Hg or less), the median pO2 was above 20 mm Hg after the 2-week cRA/IFN-induction. In this subgroup of hypoxic tumors, the median pO2 increased from 6.3 +/- 2.7 mm Hg to 27.0 +/- 5.6 mm Hg (p = 0.004, t-test for paired samples). The frequency of hypoxic readings (pO2-values < 5 mm Hg) decreased from 44.7 +/- 17.1% to 2.0 +/- 2.5% (p = 0.012, t-test for paired samples). There was, however, no obvious volume reduction after 14 weeks of cRA/IFN on clinical examination. A complete clinical remission of the local tumor was observed in 19/22 patients after radiotherapy and additional cRA/IFN-alpha-2a-treatment. In primarily hypoxic tumors (with a median pO2 below 10 mm Hg prior to treatment), 4/5 achieved complete remission.

CONCLUSIONS

Pretreatment with cRA/IFN improves oxygenation of primarily hypoxic cervical cancers. The mechanisms of action remain unclear and further investigation of the combination regimen is recommended.

Enhanced radiosensitization with interferon-alpha-2b and cisplatin in the treatment of locally advanced cervical carcinoma

PURPOSE

To evaluate the efficacy and toxicity of interferon-alpha-2b (IFN-alpha) and cisplatin given concomitantly with radiation therapy (RT) in the treatment of locally advanced cervical carcinoma.

MATERIALS AND METHODS

Twenty-one patients with stage bulky Ib-IIIb (Ib, 2; IIa, 2; IIb, 8; IIIb, 9) cervical carcinoma were treated with combined IFN-alpha (5 million IU) subcutaneously three times per week and cisplatin (25 mg/m2) i.v. infusion over 2 h weekly for 7 weeks, given concomitantly with RT (4500 cGy of external beam plus 2 brachytherapy procedures). Total radiation doses delivered ranged from 7500 to 9960 cGy (median, 9300 cGy). Follow-up ranged from 16 to 33 months (median, 25 months).

RESULTS

The 2-year local control rate was 100%. The only sites of disease recurrence were distant. Freedom from distant metastases, disease-free survival, and overall survival at 2 years was 76%. Late complication rates were high. Grade 4 rectosigmoid, bladder, and small bowel complication rates were 49, 18, and 23% at 2 years. Late toxicity was seen earlier than expected with rectosigmoid complications observed 5 to 11.5 months (median, 8 months) after completion of treatment.

CONCLUSION

Combination IFN-alpha and cisplatin produced a marked effect of enhanced radiosensitization as evidenced by 100% local tumor control and high late normal tissue complication rates. Due to the unacceptable late toxicity, its routine clinical use cannot be recommended. Further investigation is needed to determine whether a therapeutic window exists such that the use of lower doses of IFN-alpha, cisplatin, or RT can increase tumor control with more acceptable normal tissue toxicity.

p53 interference and growth inhibition in p53-mutant and overexpressing endometrial cancer cell lines

BACKGROUND

The presence of p53 mutations and associated mutant p53 overexpression has been demonstrated in many cancer systems. Whether the overexpression of mutant p53 represents cause or effect, and whether p53 mutation contributes actively to the malignant phenotype is a matter of controversy. We examined the growth effects of oligonucleotides designed to interfere with p53 expression and/or activity in p53-mutant/overexpressing endometrial cancer cell lines.

METHODS

Phosphorothioate oligonucleotides were used to target p53-related sequences in two p53-mutant/overexpressing endometrial cancer cell lines (KLE and RL95-2) and a normal fibroblast control. The ATP cell viability assay was used to measure growth effects after 6-day treatments with 27-mer and 14-mer sense (S) or antisense (AS) phosphorothioate oligodeoxyribonucleotides (oligos) targeting the promoter/ATG region of p53 and/or the p53 consensus (CON) DNA binding sequence. These sequences were designed to interfere with p53 expression and activity, respectively. Random sequences of the p53 27- and 14-mer were used as controls for nonspecific oligo effects, and a normal fibroblast cell line was used to compare oligo effects and serve as a negative p53 immunostaining control.

RESULTS

Mean +/- SE IC50 (50% growth inhibition) of the S, AS p53, and p53 CON oligos were 4.2 +/- 1.3, 4.7 +/- 0.9, and 7.6 +/- 1.4 microM, respectively, for the two endometrial cell lines combined. The AS and S p53 oligos demonstrated dose-dependent inhibitory effects in both cell lines, while p53 CON produced variable effects alone and in combination with p53 AS. In KLE, a uniform inhibitory dose response was seen with p53 CON oligos. In RL95-2, the approximate IC50 for p53 CON was 0.5-1.0 microM, but at increasing doses above this, an inverse dose response was consistently observed. Combinations of p53 AS and p53 CON oligos produced predominantly synergistic growth inhibition. Although combinations of p53 AS and p53 CON in KLE were synergistic at low doses, antagonistic effects occurred at higher concentrations. Oligos had little effect on normal fibroblast growth, with calculated IC50 > 16 microM. Equimolar combinations of p53 S and AS were antagonistic, indicating that antiproliferative effects were sequence-specific. Random oligos demonstrated some nonspecific inhibitory effects, with >25% growth inhibition at 16 microM and beyond. Immunoperoxidase staining for mutant p53 after exposure to 16 microM concentrations of p53 AS oligos demonstrated reductions in p53 staining but persistent overexpression relative to wild-type (fibroblast) cells.

CONCLUSION

Phosphorothioate oligos directed against p53 sequences in two p53-mutant endometrial cancer cell lines demonstrated antiproliferative effects. Combined anti-p53 and anti-p53 binding site oligos resulted in predominantly synergistic antiproliferative effects. The activity of sense oligos, the variable responses to p53 CON, and the persistent overexpression of mutant p53 at high concentrations of growth-inhibiting anti-p53 oligos suggest that, while promising, the antineoplastic effects of these oligos occur through complex and incompletely understood mechanisms.

A phase I pilot study of pelvic radiation and alpha-2A interferon in patients with locally advanced or recurrent rectal cancer

PURPOSE

The purpose of this pilot study was to determine the maximum tolerated dose of alpha-2a interferon given by subcutaneous injection and combined with high dose pelvic radiation for locally advanced or recurrent rectal cancer.

METHODS AND MATERIALS

In this Phase I pilot study, patients with locally advanced, unresectable, or recurrent rectal cancer with or without distant metastases received external beam pelvic radiotherapy over 5 to 6 weeks combined with escalating doses of alpha-2a interferon. Interferon was escalated in increments of 3 million units for each patient cohort, starting at 3 million units subcutaneously 3 days weekly during pelvic radiation. Radiotherapy consisted of 44 Gy (2 Gy fractions) to the pelvis followed by a boost of 6 Gy or 16 Gy to gross pelvic tumor, depending on the presence or absence of small bowel in the boost field, respectively. Between 1991 and 1993, 10 patients were treated on this study, five with locally advanced and five with locally recurrent rectal cancer.

RESULTS

At 6 million units of interferon, Grade 3 (WHO criteria) toxicities were as follows: diarrhea (one), leukopenia (one), and neutropenia (one). One patient died of a massive GI bleed at this dose level. Death was not felt to be treatment related. The maximum tolerated dose of interferon was 3 million units three times weekly with radiation. Three patients had unusual complications at 4, 6, and 6 months possibly related to treatment. The first had a right distal ureteric stricture with a right urinoma. The second had a sudden left foot drop that has remained stable. The third had sudden onset of bilateral lower extremity paraplegia with spontaneous resolution.

CONCLUSIONS

The maximally tolerated dose of interferon alpha-2a given three times weekly during pelvic radiation was 3 million units based on acute side effects. Nevertheless, even at this dose level there were three unusual subacute complications possibly related to treatment. Caution is advised when combining interferon alpha-2a with high dose pelvic radiation, especially in patients with predisposing conditions (such as diabetes) for radiotherapy complications.

gamma-Interferon administration after 90yttrium radiolabeled antibody therapy: survival and hematopoietic toxicity studies

PURPOSE

Hematopoietic toxicity is the dose-limiting factor for radioimmunotherapeutic regimens. Cytokines have been shown to decrease hematopoietic toxicity in animals exposed to whole-body irradiation. The purpose of this study was to investigate the effects of murine gamma-interferon (gamma-IFN) on survival and hematopoietic toxicity in mice treated with high dose 90yttrium labeled anticarcinoembryonic antigen (CEA) monoclonal antibody.

METHODS AND MATERIALS

Balb/c nu/nu mice were injected intravenously with 250 Ci 90Y-T84.66 (a murine anti-CEA monoclonal antibody). Thirty thousand units of gamma-IFN was administered i.v. 24 h later. Control mice received either 250 Ci 90Y-T84.66 alone or 30,000 units gamma-IFN alone. Survival, antibody biodistribution, and bone marrow histologic studies were then performed.

RESULTS

Only 7% of the animals treated with 90Y-T84.66 survived up to 40 days posttreatment, when the study was terminated. In contrast, 52% of the mice treated with both 90Y-T84.66 and gamma-IFN survived 40 days posttherapy. No toxic deaths were seen in the control group administered gamma-interferon alone. Histologic examination of the bone marrow of animals receiving 90Y-T84.66 and gamma-IFN showed cellular depletion of 40-70% of the hematopoietic cells by 48 h. Cell depletion was 50-70% and 20% by 72 h and 8 days posttherapy, respectively. The marrow of the 90Y-T84.66-treated control group was depleted to a level of 50-80% at 48 h, and remained depleted at 90% at 72 h and 8 days posttherapy. No marrow cell reduction was seen in the gamma-IFN-only treated group. Biodistribution studies showed no alterations in antibody biodistribution or kinetics that could account for the changes in bone marrow toxicity after gamma-IFN.

CONCLUSION

These results demonstrate that gamma-IFN can reduce the hematologic toxicity resulting from high dose radioimmunotherapy. Histologic studies of bone marrow suggest that gamma-IFN acts primarily to accelerate myelorestoration of the bone marrow. Further studies exploring the use of gamma-IFN as an adjunct to radioimmunotherapy are therefore warranted.

Assessment of effect of photosensitizers on cytotoxicity of photodynamic therapy in human breast cancer cell cultures

BACKGROUND

Photodynamic therapy (PDT) might be of clinical value for patients with breast cancer with local recurrences or metastasis. However, there is a need for improved photosensitizers that are effective in combination with laser light and have few, if any, side-effects. We evaluated in vitro the effectiveness of a second generation photosensitizer by testing the influence of laser light on cell cultures of a human breast carcinoma cell line, incubated with meta-tetrahydroxyphenylchlorin (m-THPC) (= Temoporfin).

EXPERIMENTAL DESIGN

Five thousand MCF-7 cells were plated in 96-well plates. Forty-eight hours before laser treatment, the cells were plated to achieve a monolayer configuration. Twenty-four hours after plating, they were incubated with m-THPC. On day 6 after treatment with m-THPC we lysed the cells to extract the intracellular ATP that correlates with the number of living cells. The ATP-CVA was used to assess the cytotoxicity of the tested photosensitizer m-THPC at various concentrations and the relevant laser light alone prior to their combination after six days of culture.

RESULTS

We found a dose-response for m-THPC alone ranging from 2 to 16 micrograms/ml. The calculated inhibition concentration to produce 50% cell kill (IC50) was 4.55 micrograms/ml. We also observed a very low cytotoxicity for laser irradiation alone but a very strong cell kill for the combination of m-THPC together with laser light.

CONCLUSIONS

PDT gave almost total cell kill at m-THPC concentrations that are not toxic in vitro.