Initial clinical response predicts outcome and is associated with dose schedule in metastatic melanoma and renal cell carcinoma patients treated with high-dose interleukin 2

Therapeutic approaches to enhance natural killer cell cytotoxicity

Enhancing the cytotoxicity of natural killer (NK) cells has emerged as a promising strategy in cancer immunotherapy, due to their pivotal role in immune surveillance and tumor clearance. This literature review provides a comprehensive overview of therapeutic approaches designed to augment NK cell cytotoxicity. We analyze a wide range of strategies, including cytokine-based treatment, monoclonal antibodies, and NK cell engagers, and discuss criteria that must be considered when selecting an NK cell product to combine with these strategies. Furthermore, we discuss the challenges and limitations associated with each therapeutic strategy, as well as the potential for combination therapies to maximize NK cell cytotoxicity while minimizing adverse effects. By exploring the wealth of research on this topic, this literature review aims to provide a comprehensive resource for researchers and clinicians seeking to develop and implement novel therapeutic strategies that harness the full potential of NK cells in the fight against cancer. Enhancing NK cell cytotoxicity holds great promise in the evolving landscape of immunotherapy, and this review serves as a roadmap for understanding the current state of the field and the future directions in NK cell-based therapies.

The prognostic significance of stable disease following high-dose interleukin-2 (IL-2) treatment in patients with metastatic melanoma and renal cell carcinoma

High-dose interleukin-2 (HD IL-2) is an approved immunotherapy agent for metastatic melanoma and renal cell carcinoma resulting in objective responses in 15-20 % of patients. An additional subset of patients achieves stable disease, and the natural history of these patients has not been well documented. We hypothesized that stable disease following HD IL-2 is associated with a survival advantage. To explore this hypothesis, a retrospective chart review of 305 patients diagnosed with metastatic melanoma or renal cell carcinoma treated with HD IL-2 was conducted. Patient characteristics, response based on standard RECIST criteria and overall survival were analyzed using the Kaplan-Meier method and associations with clinical response were compared using a log-rank test. Two hundred and forty-five patients had melanoma and 60 had renal cell carcinoma. Of these, 217 had complete data available for analysis. Fifty-nine percentage had progressive disease (PD), 26 % had stable disease (SD) and 15 % had an objective complete (CR) or partial response (PR). Median overall survival was 16.8 months for all patients with available survival data; patients with PD had a median survival of 7.9 months compared to 38.2 months for stable disease, while the median has not been reached for those with objective responses. This retrospective data support an association between overall survival and stable disease, suggesting that clinical benefit may be underestimated for patients treated with HD IL-2. The data further support the use of disease control rate (CR + PR + SD) as a more meaningful endpoint for future clinical studies of tumor immunotherapy, including future studies of HD IL-2.

Multimodality therapy for pancreatic cancer

Neoadjuvant chemoradiotherapy can be administered safely to patients with pancreatic cancer. Complete pathologic responses are rare, however, and the benefits of this approach compared with standard adjuvant therapy are uncertain. The only way to evaluate the efficacy of neoadjuvant chemoradiotherapy is a prospective trial involving a uniform patient population comparing the results of neoadjuvant and adjuvant therapy and a cohort receiving surgery alone. Such a study can be designed in an ethically sound manner but requires the collaboration of numerous institutions and careful coordination to achieve statistically conclusive results. The future of pancreatic cancer research rests on the availability and rapid transfer of new therapies from the laboratory to clinical research.

Immunotherapy of melanoma: a critical review of current concepts and future strategies

Advanced melanoma is a devastating disease with a very poor overall prognosis. There are only two agents that are approved by the FDA for use in patients with metastatic melanoma: dacarbazine and IL-2. Both agents have an overall response rate well below 20%, with only rare long-term responders noted. Metastatic melanoma is known to be one of the most resistant cancers to a plethora of treatment modalities, such as single-agent and combination chemotherapy, chemoimmunotherapy and immunotherapy with a host of immune stimulators. Indeed, researchers worldwide have recognized the lack of effective therapies and have refocused their efforts on developing novel and cutting-edge strategies of treatment. This is based on an improved understanding of the complex interactions that occur within the tumor microenvironment, and the central role that the host immune system plays in the surveillance of cancer. This review summarizes the recent results of novel immunotherapeutic regimens and focuses on cutting-edge modalities of treatment that encompass new lines of thinking in the war against cancer and, in particular, melanoma.

Multiparametric Flow Cytometric Analysis of Signal Transducer and Activator of Transcription 5 Phosphorylation in Immune Cell Subsets In vitro and following Interleukin-2 Immunotherapy

PURPOSE

Treatment with interleukin (IL)-2 (Proleukin) yields a 10% to 20% response rate in patients with metastatic melanoma or metastatic renal cell carcinoma. IL-2 is known to activate distinct signals within lymphocytes, including the Janus-activated kinase-signal transducer and activator of transcription (STAT) pathway. We examined the phosphorylation of STAT5 (P-STAT5) in IL-2-stimulated immune cells of normal subjects and in patients receiving IL-2 therapy using a novel flow cytometric assay to characterize the pattern and level of activation within immune subsets.

EXPERIMENTAL DESIGN

Normal peripheral blood mononuclear cells (PBMC) were treated in vitro with IL-2 and analyzed for P-STAT5 using an intracellular flow cytometric assay. PBMC were simultaneously evaluated for the induction of STAT5-regulated genes at the transcript level. PBMC were also obtained from patients immediately before and 1 hour after treatment with high-dose IL-2 and analyzed for the presence of P-STAT5 within immune cell subsets by dual-variable intracellular flow cytometry.

RESULTS

In vitro IL-2 treatment produced a rapid and dose-dependent increase in P-STAT5 within normal PBMC that correlated with the induction of transcript for the IL-2-responsive genes CIS, Pim-1, and SOCS1 (correlation coefficients 0.8628, 0.6667, and 0.7828, respectively). Dose-dependent induction of P-STAT5 was detected in PBMC for up to 18 hours following in vitro pulse stimulation with IL-2. P-STAT5 was detected within a subset of normal donor CD4(+) T cells (52.2 +/- 15.0%), CD8(+) T cells (57.6 +/- 25.8%), and CD56(+) natural killer (NK) cells (54.2 +/- 27.2%), but not CD14(+) monocytes or CD21(+) B cells, following in vitro IL-2 treatment. The generation of P-STAT5 within immune cell subsets after the therapeutic administration of IL-2 varied significantly between individuals. NK cells were noticeably absent in the posttreatment sample, a finding that was consistent for all patients examined. Surprisingly, activated STAT5 persisted within CD4(+) and CD8(+) T lymphocytes, as well as CD56(+) NK cells, for up to 3 weeks post-IL-2 treatment in three patients who exhibited a clinical response to therapy and in a fourth who exhibited a significant inflammatory response after 11 doses of therapy (first cycle).

CONCLUSIONS

The flow cytometric assay described herein is a highly efficient and reliable method by which to assess the cellular response to IL-2 within PBMC and specific immune effector subsets, both in vitro and in the clinical setting. Assessment of P-STAT5 in patient PBMC in response to therapeutic IL-2 administration reveals disparate responses between immune cell subsets as well as interpatient variation. Persistent activation of STAT5 within NK and T cells was an unexpected observation and requires further investigation.

Viral Vaccines for Cancer Immunotherapy

The understanding that tumor cells can be recognized and eliminated by the immune system has led to intense interest in the development of cancer vaccines. Viruses are naturally occurring agents that cause human disease but have the potential to prevent disease when attenuated forms or subunits are used as vaccines before exposure. A large number of viruses have been engineered as attenuated vaccines for the expression of tumor antigens, immunomodulatory molecules, and as vehicles for direct destruction of tumor cells or expression of highly specific gene products. This article focuses on the major viruses that are under development as cancer vaccines, including the poxviruses, adenoviruses, adeno-associated viruses, herpesviruses, retroviruses, and lentiviruses. The biology supporting these viruses as vaccines is reviewed and clinical progress is reported.

Cytokine Therapy: A Standard of Care for Metastatic Renal Cell Carcinoma?

Metastatic renal cell carcinoma (RCC) is refractory to standard cytotoxic chemotherapy regimens. The rationale for the use of cytokines in RCC is based on compelling evidence that RCC is sensitive to immunologic manipulation. Cytokine-based therapy with interleukin-2 (IL-2) or interferon (IFN)-alpha can result in objective tumor responses in as many as 15% of patients, and in selected patients, these responses can be durable. The development of targeted therapies for clear-cell RCC with the potential for greater antitumor activity and less toxicity has brought into question the role of cytokines in this patient population. However, no noncytokine therapy to date has proven curative in patients with metastatic RCC. Until results from ongoing trials clearly demonstrate superiority of newer agents over IFN-alpha or IL-2, these agents should remain a standard of care for the treatment of RCC.