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

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.

Genomic amplification of Fanconi anemia complementation group A (FancA) in head and neck squamous cell carcinoma (HNSCC): Cellular mechanisms of radioresistance and clinical relevance

Radio (chemo) therapy is a crucial treatment modality for head and neck squamous cell carcinoma (HNSCC), but relapse is frequent, and the underlying mechanisms remain largely elusive. Therefore, novel biomarkers are urgently needed. Previously, we identified gains on 16q23-24 to be associated with amplification of the Fanconi anemia A (FancA) gene and to correlate with reduced progression-free survival after radiotherapy. Here, we analyzed the effects of FancA on radiation sensitivity in vitro, characterized the underlying mechanisms, and evaluated their clinical relevance. Silencing of FancA expression in HNSCC cell lines with genomic gains on 16q23-24 resulted in significantly impaired clonogenic survival upon irradiation. Conversely, overexpression of FancA in immortalized keratinocytes conferred increased survival accompanied by improved DNA repair, reduced accumulation of chromosomal translocations, but no hyperactivation of the FA/BRCA-pathway. Downregulation of interferon signaling as identified by microarray analyses, enforced irradiation-induced senescence, and elevated production of the senescence-associated secretory phenotype (SASP) appeared to be candidate mechanisms contributing to FancA-mediated radioresistance. Data of the TCGA HNSCC cohort confirmed the association of gains on 16q24.3 with FancA overexpression and impaired overall survival. Importantly, transcriptomic alterations similar to those observed upon FancA overexpression in vitro strengthened the clinical relevance. Overall, FancA amplification and overexpression appear to be crucial for radiotherapeutic failure in HNSCC.

Phase 2 Randomized Controlled Trial of Radiation Therapy Plus Concurrent Interferon-Alpha and Retinoic Acid Versus Cisplatin for Stage III Cervical Carcinoma

PURPOSE

Because a combination of retinoic acid, interferon-alpha, and radiation therapy demonstrated synergistic action and effectiveness to treat advanced cervical cancers in earlier studies, we designed this randomized phase 2 open-label trial to assess efficacy and safety of interferon alpha-2b (IFN) and 13-cis-retinoic acid (RA) administered concomitantly with radiation therapy (IFN-RA-radiation) to treat stage III cervical cancer.

METHODS AND MATERIALS

Stage III cervical cancer patients were randomized to study and control groups in a 1:1 ratio. All patients were treated with radiation therapy; study arm patients received IFN (3 × 10(6) IU subcutaneously) 3 times a week for 4 weeks and daily RA (40 mg orally) for 30 days starting on day 1 of radiation, whereas control arm patients received weekly cisplatinum (40 mg/m(2)) for 5 weeks during radiation. Patients were followed for 3 years. The primary endpoint was overall survival at 3 years.

RESULTS

Patients in the study (n=104) and control (n=105) groups were comparable for clinicopathological characteristics, radiation therapy-related variables and treatment response. Proportions of disease-free patients in the study and control groups were 38.5% and 44.8%, respectively, after median follow-up of 29.2 months. Hazard ratios were 0.67 (95% confidence interval [CI]: 0.44-1.01) and 0.69 (95% CI: 0.44-1.06) for overall and disease-fee survival, respectively, comparing the study group to control, and demonstrated an inferior outcome with RA-IFN-radiation, although differences were statistically nonsignificant. Kaplan-Meier curves of disease-free and overall survival probabilities also showed inferior survival in the study group compared to those in the control. Acute toxicities of chemoradiation were significantly higher with 2 acute toxicity-related deaths.

CONCLUSIONS

Treatment with RA-IFN-radiation did not demonstrate survival advantage over chemoradiation despite being less toxic. The trends predicted an inferior outcome with the RA-IFN combination.

Pharmacotherapy options for locally advanced and advanced cervical cancer

Cervical cancer continues to be a significant health burden worldwide. Globally, the majority of cancers are locally advanced at diagnosis; hence, radiation remains the most frequently used therapeutic modality. Currently, the value of adding cisplatin or cisplatin-based chemotherapy to radiation for the treatment of locally advanced cervical cancer is strongly supported by randomized studies and meta-analyses. Nevertheless, despite these significant achievements, therapeutic results are far from optimal; thus, novel therapies need to be investigated. A recent, randomized, phase III trial has shown for the first time that combination chemotherapy with cisplatin and gemcitabine concurrently with radiation improves parameters of survival over cisplatin alone and establishes a new standard for the management of locally advanced cervical cancer. On the other hand, advanced disease, presenting either as an International Federation of Gynecology and Obstetrics (FIGO) stage IVB or as persistent or recurrent to primary therapy without local curative options, remains a devastating group of diseases with no options other than palliative chemotherapy. Recent results from the GOG (Gynecologic and Oncologic Group)-204 study demonstrate that cisplatin-doublets with paclitaxel, vinorelbine, gemcitabine or topotecan only produce small improvements in survival, although with different toxicity patterns; hence, patient-related factors are important when choosing any one of these regimens. The role of targeted therapies both in locally advanced and advanced disease is promising, but still at an investigational stage.

Gene expression changes in cervical squamous cell carcinoma after initiation of chemoradiation and correlation with clinical outcome

PURPOSE

The purpose of this study was to investigate early gene expression changes after chemoradiation in a human solid tumor, allowing identification of chemoradiation-induced gene expression changes in the tumor as well as the tumor microenvironment. In addition we aimed to identify a gene expression profile that was associated with clinical outcome.

METHODS AND MATERIALS

Microarray experiments were performed on cervical cancer specimens obtained before and 48 h after chemoradiation from 12 patients with Stage IB2 to IIIB squamous cell carcinoma of the cervix treated between April 2001 and August 2002.

RESULTS

A total of 262 genes were identified that were significantly changed after chemoradiation. Genes involved in DNA repair were identified including DDB2, ERCC4, GADD45A, and XPC. In addition, significantly regulated cell-to-cell signaling pathways included insulin-like growth factor-1 (IGF-1), interferon, and vascular endothelial growth factor signaling. At a median follow-up of 41 months, 5 of 12 patients had experienced either local or distant failure. Supervised clustering analysis identified a 58-gene set from the pretreatment samples that were differentially expressed between patients with and without recurrence. Genes involved in integrin signaling and apoptosis pathways were identified in this gene set. Immortalization-upregulated protein (IMUP), IGF-2, and ARHD had particularly marked differences in expression between patients with and without recurrence.

CONCLUSIONS

Genetic profiling identified genes regulated by chemoradiation including DNA damage and cell-to-cell signaling pathways. Genes associated with recurrence were identified that will require validation in an independent patient data set to determine whether the 58-gene set associated with clinical outcome could be useful as a prognostic assay.

Toxicity of combined treatment of adjuvant irradiation and interferon alpha2b in high-risk melanoma patients

Surgically resected stage III melanoma patients commonly receive adjuvant therapy with interferon (IFN) alpha2b. For those patients with high-risk features of draining node recurrence, radiation therapy can also be considered as a treatment option. The purpose of this retrospective study was to assess the efficacy and radiation-related toxicity of this combined therapy. Eighteen patients receiving adjuvant IFNalpha2b therapy during radiation therapy, or within 1 month of its completion, were reviewed retrospectively and analysed for outcome. Radiation was delivered at 600 cGy dose per fraction, in 16 out of 18 patients, twice a week, and at 200 cGy dose per fraction in two patients five times a week. Total radiation dose and number of fractions were as follows: 30 Gy/5 fr (n=8), 36 Gy/6 fr (n=8) and 50 Gy/25 fr (n=2). The percentage of disease-free patients, with no local recurrence, at 3 years was 88%. In 10 patients, IFNalpha2b was administered concurrently with radiotherapy; in three, within 30 days before or after radiation; and in five, more than 30 days after radiation. All the patients experienced acute skin reactions, grade I on the Radiation Therapy Oncology Group (RTOG) scale. Late radiation-related toxicity was seen in one patient with grade III (RTOG) skin reaction and two with grade IV (RTOG) radiation-induced myelitis. Concurrent use of adjuvant radiotherapy and IFNalpha2b might enhance radiation-induced toxicity, and special care should be taken when the spinal cord is included in the radiation field.

Radiosensitizers in cervical cancer. Cisplatin and beyond

Cervical cancer continues to be a significant health burden worldwide. Globally, the majority of cancers are locally advanced at diagnosis; hence, radiation remains the most frequently used therapeutical modality. Currently, the value of adding cisplatin or cisplatin-based chemotherapy to radiation for treatment of locally advanced cervical cancer is strongly supported by randomized studies and meta-analyses. Nevertheless, despite these significant achievements, therapeutic results are far from optimal; thus, novel therapies need to be assayed. A strategy currently being investigated is the use of newer radiosensitizers alone or in combination with platinum compounds. In the present work, we present preclinical information on known and newer cytotoxic agents as radiosensitizers on cervical cancer models, as well as the clinical information emanating from early phase trials that incorporate them to the cervical cancer management. In addition, we present the perspectives on the combined approach of radiation therapy and molecular target-based drugs with proven radiosensitizing capacity.

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.

Evidence that involucrin, a marker for differentiation, is oxygen regulated in human squamous cell carcinomas

The majority of hypoxic cells in squamous cell carcinomas of the head and neck and cervix express involucrin, a molecular marker for differentiation. This raises the question of whether involucrin is an oxygen-regulated protein and, if so, whether it could serve as an endogenous marker for tumour hypoxia. Consistent with oxygen regulation, involucrin protein was found to increase with increasing hypoxia in confluent cultures of moderately differentiated human SCC9 cells. Cells harvested at the point of confluence and exposed to graded concentrations of oxygen revealed a K_m of approximately 15 mmHg for involucrin induction. This is similar to K_ms for HIF-1α, CAIX and VEGF. Involucrin induction showed a steep dependence on pO₂ with a transition from minimum to maximum expression occurring over less than an order of magnitude change in pO₂. In contrast to SCC9 cells, involucrin was not induced by hypoxia in poorly differentiated SCC4 cells. It is concluded that involucrin is an oxygen-regulated protein, but that differentiation modulates its transcription status with respect to hypoxia induction.

1alpha,25-dihydroxyvitamin D(3) (calcitriol) and its analogue, 19-nor-1alpha,25(OH)(2)D(2), potentiate the effects of ionising radiation on human prostate cancer cells

Radiotherapy with external beam radiation or brachytherapy is an established therapeutic modality for prostate cancer. Approximately 30% of patients with localised prostate cancer relapse at the irradiated site. Secondary effects of ionising radiation (IR), for example, bowel and bladder complications, are common. Thus, the search for biological response modifiers that could potentiate the therapeutic effects of radiation and limit the occurrence of serious side effects is an important task in prostate cancer therapy. 1alpha,25-Dihydroxyvitamin D(3) (calcitriol), the active metabolite of vitamin D, and its analogues are under investigation for the treatment of several malignancies including prostate cancer. Here, we report that 1alpha,25-dihydroxyvitamin D(3) and its less calcaemic analogue 19-nor-1alpha,25-(OH)(2)D(2) (Zemplar) act synergistically with IR to inhibit the growth of the human prostate cancer cells in vitro. 1alpha,25-dihydroxyvitamin D(3) potentiated IR-induced apoptosis of LNCaP cells, and nanomolar doses of 1alpha,25-dihydroxyvitamin D(3) and 19-nor-1alpha,25-(OH)(2)D(2) showed synergistic inhibition of growth of LNCaP cells at radiobiologically relevant doses of IR (1-2 Gy). At higher doses of IR, the combination of 1alpha,25-dihydroxyvitamin D(3) and IR or 19-nor-1alpha,25-(OH)(2)D(2) and IR resulted in moderate antagonism. The synergistic effect at radiobiologically relevant doses of radiation suggests that a combination of 1alpha,25-dihydroxyvitamin D(3) or 19-nor-1alpha,25-(OH)(2)D(2) with IR could permit a reduction in the dose of radiation given clinically and thus potentially reduce treatment-related morbidity.

Combined-modality treatment of solid tumors using radiotherapy and molecular targeted agents

PURPOSE

Molecular targeted agents have been combined with radiotherapy (RT) in recent clinical trials in an effort to optimize the therapeutic index of RT. The appeal of this strategy lies in their potential target specificity and clinically acceptable toxicity.

DESIGN

This article integrates the salient, published research findings into the underlying molecular mechanisms, preclinical efficacy, and clinical applicability of combining RT with molecular targeted agents. These agents include inhibitors of intracellular signal transduction molecules, modulators of apoptosis, inhibitors of cell cycle checkpoints control, antiangiogenic agents, and cyclo-oxygenase-2 inhibitors.

RESULTS

Molecular targeted agents can have direct effects on the cytoprotective and cytotoxic pathways implicated in the cellular response to ionizing radiation (IR). These pathways involve cellular proliferation, DNA repair, cell cycle progression, nuclear transcription, tumor angiogenesis, and prostanoid-associated inflammation. These pathways can also converge to alter RT-induced apoptosis, terminal growth arrest, and reproductive cell death. Pharmacologic modulation of these pathways may potentially enhance tumor response to RT though inhibition of tumor repopulation, improvement of tumor oxygenation, redistribution during the cell cycle, and alteration of intrinsic tumor radiosensitivity.

CONCLUSION

Combining RT and molecular targeted agents is a rational approach in the treatment of solid tumors. Translation of this approach from promising preclinical data to clinical trials is actively underway.

Retinoic acid modulates the radiosensitivity of head-and-neck squamous carcinoma cells grown in collagen gel

PURPOSE

Collagen gels are increasingly regarded as reliable scaffolds for studying cells in vitro, displaying the same three-dimensional network of collagen fibers as encountered in vivo. As a contribution to therapeutic control of head-and-neck cancer, we grew HSCO86 cells in collagen gel and assessed their behavior in the presence of retinoic acid (RA) and radiation.

METHODS AND MATERIALS

The malignant epithelial cell line HSCO86 was isolated from a postirradiation human oropharyngeal squamous carcinoma; it was EGFR-negative by immunocytochemical criteria. The cells were embedded in hydrated collagen I at a density of 10(6) cells/mL, and on Days 8, 10, and 12 of culture, they were treated with 10(-5) M retinoic acid. Radiation was administered using two different schedules: simultaneously with RA in three daily doses totaling 10 Gy, or with a single dose of 8 Gy on Day 29 of culture, after the effects of RA had taken place. Cell proliferation was evaluated by the MTT assay, whereas morphometric characteristics were detected in the cultured gels directly or in the gels after they were fixed and stained with hematoxylin.

RESULTS

Contrary to growth in monolayer, where HSCO86 cells displayed a high proliferation rate, in collagen gel only a tiny fraction of the cells, usually less than 0.02%, survived the environmental stress; these cells spontaneously organized themselves into clonal multicellular spheroids growing up to 0.8 mm in diameter. After exposure to 10(-5) M retinoic acid, cell proliferation first declined and then, about 15 days after treatment, it started to increase to a level far above that in the control group. This surge in proliferation was ascribed to the appearance of numerous fibroblast-like cells at the edge of the spheroids. These cells, called HSCO-F, were the result of epithelial-to-mesenchymal conversion. When the gels were disaggregated by collagenase, and the cells were seeded in monolayer, HSCO-F cells reversed their morphology into parental HSCO86 cells. Treatment of collagen gels with 10 Gy, fractionated in three daily doses, did not substantially affect the growth of HSCO86 spheroids. However, when radiation was given simultaneously with RA, cell growth was significantly inhibited, both in terms of cell proliferation and size of spheroids (p < 0.0001 vs. untreated controls). This synergism applied mainly to parental HSCO86 cells, because no significant damage was induced by radiation on the HSCO-F cells previously generated by treatment with RA.

CONCLUSION

Differences in the radiosensitivity of HSCO86 and HSCO-F cells are surprising in view of their common origin; this suggests a scenario in which, to overcome a microenvironmental stress, head-and-neck carcinoma cells can temporarily shift from an epithelial to a mesenchymal phenotype. In particular, morphologic and functional data suggested that HSCO-F cells were transformed into vascular endothelial cells whose characteristics included the following: (1) distinctive expression of Factor VIII and beta(1)-integrin, not detected in parental HSCO86 cells; (2) active migration in the collagen network by extruded pseudopodia, frequently appearing as colonies of filamentous cells aligned along the radial axis of the spheroids; and (3) efficient contraction of floating collagen gels. The implication of our study is that head-and-neck carcinomas may respond to RA treatment by selecting cell populations both resistant to radiation and capable of migrating inside the connective tissue, mimicking the behavior of vascular capillaries.

Combined adjuvant radiation and interferon-alpha 2B therapy in high-risk melanoma patients: the potential for increased radiation toxicity

PURPOSE

Surgically resected melanoma patients with high-risk features commonly receive adjuvant therapy with interferon-alpha 2b combined with radiation therapy; the purpose of our study was to evaluate the potential enhancement of radiation toxicity by interferon.

METHODS AND MATERIALS

Patients at LDS Hospital and the University of Utah Medical Center in Salt Lake City treated with interferon during radiotherapy or within 1 month of its completion were retrospectively identified, and their charts were reviewed. If possible, the patients were asked to return to the LDS Hospital radiation therapy department for follow-up.

RESULTS

Five of 10 patients receiving interferon-alpha 2b therapy during radiation therapy or within 1 month of its completion experienced severe subacute/late complications of therapy. Severe subacute/late complications included two patients with peripheral neuropathy, one patient with radiation necrosis in the brain, and two patients with radiation necrosis in the s.c. tissue. One patient with peripheral neuropathy and one patient with radiation necrosis also developed lymphedema.

CONCLUSIONS

In vitro studies have identified a radiosensitizing effect by interferon-alpha on certain cell lines, which suggests the possibility that patients treated with interferon and radiation therapy may experience more severe radiation toxicities. We have observed severe subacute/late complications in five of 10 patients treated with interferon-alpha 2b during radiation therapy or within 1 month of its completion. Although an observational study of 10 patients lacks the statistic power to reach conclusions regarding the safety and complication rates of combined interferon and radiation therapy, it is sufficient to raise concerns and suggest the need for prospective studies.

Retinoid therapy of childhood cancer

In vitro studies that showed RA could cause growth arrest and differentiation of myelogenous leukemia and neuroblastoma led to clinical trials of retinoids in APL and neuroblastoma that increased survival for both of those diseases. In the case of APL, ATRA has been the drug of choice, and preclinical and clinical data support direct combinations of ATRA with cytotoxic chemotherapy. For neuroblastoma, a phase I study defined a dose of 13-cis-RA, which was tolerable in patients after myeloablative therapy, and a phase III trial that showed postconsolidation therapy with 13-cis-RA improved EFS for patients with high-risk neuroblastoma. Preclinical studies in neuroblastoma indicate that ATRA or 13-cis-RA can antagonize cytotoxic chemotherapy and radiation, so use of 13-cis-RA in neuroblastoma is limited to maintenance after completion of cytotoxic chemotherapy and radiation. A limitation on the antitumor benefit of ATRA in APL is the marked decrease in drug levels that occurs during therapy as a result of induction of drug metabolism, resulting in a shorter drug half-life and decreased plasma levels. Although early studies sought to overcome the pharmacologic limitations of ATRA therapy in APL, the demonstration that ATO is active against APL in RA-refractory patients has led to a focus on studies employing ATO. Use of 13-cis-RA in neuroblastoma has avoided the decreased plasma levels seen with ATRA. It is likely that recurrent disease seen during or after 13-cis-RA therapy in neuroblastoma is due to tumor cell resistance to retinoid-mediated differentiation induction. Studies in neuroblastoma cell lines resistant to 13-cis-RA and ATRA have shown that they can be sensitive, and in some cases collaterally hypersensitive, to the cytotoxic retinoid fenretinide. Fenretinide induces tumor cell cytotoxicity rather than differentiation, acts independently from RA receptors, and in initial phase I trials has been well tolerated. Clinical trials of fenretinide, alone and in combination with ceramide modulators, are in development.