Stereotactic Ablative Radiation Therapy for Oligoprogressive Renal Cell Carcinoma

PURPOSE

Oligoprogression, defined as limited sites of progression on systemic therapy, in patients with metastatic renal cell carcinoma (mRCC) is not uncommon, possibly because of inter- and intratumoral heterogeneity. We evaluated the effect of stereotactic ablative radiation therapy (SAbR) for longitudinal control of oligoprogressive mRCC.

METHODS AND MATERIALS

Patients with extracranial mRCC were included in this retrospective analysis if they progressed in ≤3 sites on systemic therapy while demonstrating response/stability at other sites and received SAbR to all progressing sites without switching systemic therapy. Our primary endpoint was modified progression-free survival (mPFS), which we calculated from the start of SAbR to the start of a subsequent systemic therapy, death, or loss to follow-up.

RESULTS

We identified 36 patients with a median follow-up of 20.4 months (interquartile range, 10.9-29.4). Forty-three sites were treated with SAbR with a median dose of 36 Gy (range, 18-50) in 3 fractions (range, 1-5). Median time to SAbR from the start of systemic therapy was 11.4 months (interquartile range, 6.1-17.1). Median mPFS was 9.2 months (95% confidence interval [CI], 5.9-13.2). Patients receiving SAbR while on immunotherapy exhibited a longer median mPFS (>28.4 months, log-rank P = .0001) than patients not on immunotherapy (9.2 months). Median overall survival from SAbR administration was 43.4 months (95% CI, 21.5-not Reached). The 1-year local control rate was 93% (95% CI, 78.7-97.5). Most SAbR-related toxicities were grade 1 to 2 (33% of patients), with one grade 5 hemoptysis event possibly related to SAbR or disease progression.

CONCLUSIONS

SAbR has the potential to extend the the duration of current systemic therapy for selected patients with mRCC, preserving subsequent therapies for later administration possibly enabling longer treatment duration.

Low-dose radiation treatment enhances systemic antitumor immune responses by overcoming the inhibitory stroma

Background

Despite some successes with checkpoint inhibitors for treating cancer, most patients remain refractory to treatment, possibly due to the inhibitory nature of the tumor stroma that impedes the function and entry of effector cells. We devised a new technique of combining immunotherapy with radiotherapy (XRT), more specifically low-dose XRT, to overcome the stroma and maximize systemic outcomes.

Methods

We bilaterally established 344SQ lung adenocarcinoma tumors in 129Sv/Ev mice. Primary and secondary tumors were irradiated with either high-dose or low-dose of XRT with systemic anti-programmed cell death protein 1 and anti-cytotoxic T-lymphocyte associated protein 4 administration. Survival and tumor growth were monitored for the various groups, and secondary tumors were phenotyped by flow cytometry for immune populations. Tumor growth factor-beta (TGF-β) cytokine levels were assessed locally after low-dose XRT, and specific immune-cell depletion experiments were conducted to identify the major contributors to the observed systemic antitumor effect.

Results

Through our preclinical and clinical studies, we observed that when tumor burden was high, there was a necessity of combining high-dose XRT to ‘prime’ T cells at the primary tumor site, with low-dose XRT directed to secondary (metastatic) tumors to ‘modulate the stroma’. Low-dose XRT improved the antitumor outcomes of checkpoint inhibitors by favoring M1 macrophage polarization, enhancing natural killer (NK) cell infiltration, and reducing TGF-β levels. Depletion of CD4⁺ T cells and NK cells abrogated the observed antitumor effect.

Conclusion

Our data extend the benefits of low-dose XRT to reprogram the tumor environment and improve the infiltration and function of effector immune cells into secondary tumors.

Bone morphogenetic protein 7 promotes resistance to immunotherapy

Immunotherapies revolutionized cancer treatment by harnessing the immune system to target cancer cells. However, most patients are resistant to immunotherapies and the mechanisms underlying this resistant is still poorly understood. Here, we report that overexpression of BMP7, a member of the TGFB superfamily, represents a mechanism for resistance to anti-PD1 therapy in preclinical models and in patients with disease progression while on immunotherapies. BMP7 secreted by tumor cells acts on macrophages and CD4⁺ T cells in the tumor microenvironment, inhibiting MAPK14 expression and impairing pro-inflammatory responses. Knockdown of BMP7 or its neutralization via follistatin in combination with anti-PD1 re-sensitizes resistant tumors to immunotherapies. Thus, we identify the BMP7 signaling pathway as a potential immunotherapeutic target in cancer.

The mechanisms underlying resistance to immunotherapy are still poorly understood. Here, the authors show that BMP7, a molecule part of the TGF-beta superfamily, suppresses proinflammatory antitumor responses and may represent a target for overcoming resistance to PD1 inhibitors.

Triple Therapy with MerTK and PD1 Inhibition Plus Radiotherapy Promotes Abscopal Antitumor Immune Responses

PURPOSE

Radiotherapy (RT) traditionally has been used for local tumor control in the treatment of cancer. The recent discovery that radiotherapy can have anticancer effects on the immune system has led to recognition of its ability to sensitize the tumor microenvironment to immunotherapy. However, radiation can also prompt adverse immunosuppressive effects that block aspects of systemic response at other tumor sites. Our hypothesis was that inhibition of the MER proto-oncogene tyrosine kinase (MerTK) in combination with anti-programmed cell death-1 (α-PD1) checkpoint blockade will enhance immune-mediated responses to radiotherapy.

EXPERIMENTAL DESIGN

We tested the efficacy of this triple therapy (Radiation + α-PD1 + α-MerTK mAbs) in 129Sv/Ev mice with bilateral lung adenocarcinoma xenografts. Primary tumors were treated with stereotactic radiotherapy (36 Gy in 3 12-Gy fractions), and tumors were monitored for response.

RESULTS

The triple therapy significantly delayed abscopal tumor growth, improved survival rates, and reduced numbers of lung metastases. We further found that the triple therapy increased the activated CD8⁺ and NK cells populations measured by granzyme B expression with upregulation of CD8⁺CD103⁺ tissue-resident memory cells (T_RM) within the abscopal tumor microenvironment relative to radiation only.

CONCLUSIONS

The addition of α-PD1 + α-MerTK mAbs to radiotherapy could alter the cell death to be more immunogenic and generate adaptive immune response via increasing the retention of T_RM cells in the tumor islets of the abscopal tumors which was proven to play a major role in survival of non-small cell lung cancer patients.

Radiation therapy and immunotherapy: what is the optimal timing or sequencing?

Radiotherapy is a component of the standard of care for many patients with locally advanced nonmetastatic tumors and increasingly those with oligometastatic tumors. Despite encouraging advances in local control and progression-free and overall survival outcomes, continued manifestation of tumor progression or recurrence leaves room for improvement in therapeutic efficacy. Novel combinations of radiation with immunotherapy have shown promise in improving outcomes and reducing recurrences by overcoming tumor immune tolerance and evasion mechanisms via boosting the immune system's ability to recognize and eradicate tumor cells. In this review, we discuss preclinical and early clinical evidence that radiotherapy and immunotherapy can improve treatment outcomes for locally advanced and metastatic tumors, elucidate underlying molecular mechanisms and address strategies to optimize timing and sequencing of combination therapy for maximal synergy.

Low dose radiotherapy promotes immune-mediated anti-tumor responses

In an immune competent host, immune surveillance maintains the guards against abnormal cell growth, therefore establishing the need for tumors to evade immunity to grow. Tumors tend to mask themselves with an inhibitory stroma, rich with T regulatory cells, Myeloid-derived suppressor cells, Cancer associated fibroblasts, and pro-tumor M2 macrophages. Despite current advances with checkpoint inhibitors and cell-based therapies, the majority of cancer patients remain refractory to treatment due to the presence of the stroma and the inability of effector cells to penetrate. Radiotherapy (XRT) has been traditionally used to control tumors locally. More recently, we developed the RadScopal technique that combines high dose XRT (H-XRT) to release antigens and prime T-cells with low dose XRT (L-XRT) to overcome the stroma, favor the polarization of M1 macrophages, reduce TGF-β levels, and enhance NK cell infiltration. In the 129Sv/Ev murine model of bilaterally transplanted tumors, RadScopal treatment significantly improved the outcomes of anti-CTLA-4 and anti-PD1 checkpoint inhibitors and controlled the growth of primary as well as distal secondary tumors treated with L-XRT. The RadScopal efficacy was nulled when using nude mice lacking effector adaptive immunity. Moreover, specific immune-cell depletion studies highlighted the importance of CD4+ T-cells and NK cells to carry out the anti-tumor functions. Our radio-immunotherapeutic approach was operative in other models such as Lewis Lung Carcinoma, where L-XRT retarded the growth of secondary tumors. In conclusion, L-XRT significantly augmented checkpoint blockers with potential future application to cell therapies (CAR-T and TCR) to extend the benefits to more patients.

Role of Radiation Therapy in Modulation of the Tumor Stroma and Microenvironment

In recent decades, there has been substantial growth in our understanding of the immune system and its role in tumor growth and overall survival. A central finding has been the cross-talk between tumor cells and the surrounding environment or stroma. This tumor stroma, comprised of various cells, and extracellular matrix (ECM), has been shown to aid in suppressing host immune responses against tumor cells. Through immunosuppressive cytokine secretion, metabolic alterations, and other mechanisms, the tumor stroma provides a complex network of safeguards for tumor proliferation. With recent advances in more effective, localized treatment, radiation therapy (XRT) has allowed for strategies that can effectively alter and ablate tumor stromal tissue. This includes promoting immunogenic cell death through tumor antigen release to increasing immune cell trafficking, XRT has a unique advantage against the tumoral immune evasion mechanisms that are orchestrated by stromal cells. Current studies are underway to elucidate pathways within the tumor stroma as potential targets for immunotherapy and chemoradiation. This review summarizes the effects of tumor stroma in tumor immune evasion, explains how XRT may help overcome these effects, with potential combinatorial approaches for future treatment modalities.

Anti-glucocorticoid-induced Tumor Necrosis Factor-Related Protein (GITR) Therapy Overcomes Radiation-Induced Treg Immunosuppression and Drives Abscopal Effects

Despite the potential to cure metastatic disease, immunotherapy on its own often fails outright or early on due to tumor immune evasion. To address this obstacle, we investigated combinations of anti-GITR, anti-PD1 and radiation therapy (XRT) in our previously developed anti-PD1 resistant 344SQ non-small cell lung adenocarcinoma preclinical tumor model. We hypothesized that targeting multiple mechanisms of immune evasion with this triple therapy would lead to an enhanced tumor-specific immune response and improve survival more so than any mono- or dual therapy. In a two tumor 344SQR murine model, treatment with anti-GITR, anti-PD1, and XRT led to significantly improved survival and an abscopal response, with half of the mice becoming tumor free. These mice showed durable response and increased CD4+ and CD8+ effector memory on tumor rechallenge. Regulatory T cells (Tregs) expressed the highest level of GITR at the tumor site and anti-GITR therapy drastically diminished Tregs at the tumor site. Anti-tumor effects were largely dependent on CD4+ T cells and partially dependent on CD8+ T cells. Anti-GITR IgG2a demonstrated superior efficacy to anti-GITR IgG1 in driving antitumor effects. Collectively, these results suggest that combinatorial strategies targeting multiple points of tumor immune evasion may lead to a robust and lasting antitumor response.

Radiation Followed by OX40 Stimulation Drives Local and Abscopal Antitumor Effects in an Anti-PD1-Resistant Lung Tumor Model

Purpose: Radiation is used extensively to treat localized cancer, but improved understanding of its effects on the immune system has increased interest in its potential systemic (abscopal) effects, particularly in combination with checkpoint inhibitors such as anti-PD1. The majority of patients either do not respond or develop resistance to monotherapy over time. Here, we investigated the efficacy of OX40 (CD134) stimulation as an alternative immunotherapeutic approach in combination with radiotherapy (XRT) in a murine model of anti-PD1-resistant lung tumors.Experimental Design: We established a bilateral tumor model in 129Sv/Ev mice using an anti-PD1-resistant lung tumor cell line. Primary tumors were treated with intratumoral injection of an OX40 agonist antibody, given as adjuvant therapy after XRT (36 Gy in three 12-Gy fractions), whereas secondary tumors were left untreated to investigate abscopal outcomes.Results: The combination of XRT followed by OX40 stimulation effectively inhibited local and systemic antitumor growth, limited lung metastases, and improved survival rates. This treatment regimen augmented CD4⁺ and CD8⁺ T-cell expansion. XRT induced the expression of OX40 on T cells in tumors and spleens and increased the percentages of splenic CD103⁺ dendritic cells.Conclusions: Our data extend the benefits of radiation to systemic disease control, especially when combined with anti-OX40 agonist to promote immunologically mediated abscopal effects. Moreover, this study provides a rational treatment approach and sequence to overcome anti-PD1-resistant poorly immunogenic tumors. Clin Cancer Res; 24(22); 5735-43. ©2018 AACR.

Indoleamine 2,3-dioxygenase 1 inhibition targets anti-PD1-resistant lung tumors by blocking myeloid-derived suppressor cells

Indoleamine 2,3-dioxygenase 1 (IDO1), involved in the catabolism of tryptophan (Trp) to kynurenine (Kyn) is an important regulator of tumor-mediated immunosuppression implicated in resistance to anti-PD1 immunotherapy. We investigated the role of IDO1 in an anti-PD1-resistant lung cancer model (344SQ_R) compared to the parental 344SQ tumors (344SQ_P). IDO1 was overexpressed in tumor-infiltrating leukocytes, and plasma Kyn levels were increased, in 344SQ_R vs. 344SQ_P. The IDO1 inhibitor INCB023843 retarded tumor growth and reduced lung metastases in 344SQ_R. IDO1 was expressed at higher levels in F4/80⁺Gr1^intCD11b⁺ myeloid-derived suppressor cells (MDSCs) that were prominent in 344SQ_R. The INCB023843 reduced IDO1 expression and percentages of these MDSCs while increasing CD8⁺ T cells infiltration, hence reactivating antitumor T-cell responses in 344SQ_R. Therefore, IDO1 inhibition holds promise for treating lung cancer that does not respond to anti-PD1 therapy.

Abstract 1017: Lipid metabolic reprogramming drives resistance to PD1 blockage

The mechanisms underlying immunosuppression and resistance to PD1 inhibitors in cancer are not well understood. We attempted to fill this gap with an integrated analysis of mRNA, microRNA, and protein expression in an anti-PD1-resistant lung adenocarcinoma mouse model. The model was created by in vivo passage of 344SQ murine lung cancer cells (p53R172HΔg/+K-rasLA1/+) in a syngeneic host repeatedly dosed with anti-mouse PD1 antibodies. Anti-PD1-resistant 344SQ (344SQ_R) and 344SQ parental (344SQ_P) cells were then inoculated into syngeneic 129Sv/ev mice, which were then dosed twice with anti-PD1 or control IgG antibodies. Tumor tissues were collected and analyzed as follows: transcriptome with Affymetrix; protein levels by reverse phase protein array analysis; signature enrichment by gene set enrichment analysis; metabolome by mass spectrometry; and lipid content with fluorescent probes Oil O rad and BODIPY. We also isolated tumor-infiltrating immune cells for flow cytometry and gene expression analyses. We identified lipid-related metabolic pathways as being the most highly enriched in anti-PD1-resistant tumors (344SQ_R) vs. their 344SQ_P counterparts; the resistant cells also had more lipid droplets than the 344SQ_P cells. The anti-PD1-resistant tumors overexpressed several genes involved in lipogenesis and fatty acid pathways (e.g., fatty acid binding proteins [FABPs], fatty acid synthase, acetyl-coA-acyltransferase 2, fatty acid elongases). Specifically, FABP overexpression promoted fatty acid uptake and lipid-droplet accumulation in resistant tumors. Lipid-sensitive targets linked to inflammation and insulin signaling (e.g,. stress-activated kinases such as JNK and NFκB) were altered in 344SQ_R vs. 344SQ_P tumors. Mechanistically, JNK downregulation by NFκB-regulated microRNAs protected PD1-resistant tumors from lipotoxicity caused by FABPs upregulation and fatty acid uptake. FABP levels were higher in plasma from 344SQ_R than from 344SQ_P tumors. Tumor-infiltrating macrophages from 344SQ_R tumors had 4 times the amount of FABP mRNA than parental tumors and a correspondingly higher percentage of M2-like macrophages. 344SQ_R tumors promoted immune suppressive cells by upregulating FABPs expression in M2-like macrophages, marked by increased fatty acid intake and fatty acid oxidation. Conversely, percentages of CD4+ and CD8+ tumor-infiltrating lymphocytes were reduced in the resistant tumors. These results suggest that lipid metabolic rewiring drives resistance PD1 inhibitors supporting the accumulation of immunosuppressive cells, including M2-like macrophages, preventing type I immune responses elicited by T cells. Collectively, these findings reveal new potential lipid-related targets for drug development or new treatments combining inhibitors of these targets with anti-PD1 therapy.

Citation Format: Maria A. Cortez, Sharareh Niknam, Efrosini Cuko, Jonathan E. Schoenhals, Hampartsoum Barsoumian, Ahmed I. Younes, Ailin Li, Jody V. Vykoukal, Cristina Ivan, George A. Calin, Patrick Hwu, James W. Welsh. Lipid metabolic reprogramming drives resistance to PD1 blockage [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1017. doi:10.1158/1538-7445.AM2017-1017

Targeting anti-PD1-resistant tumors via indoleamine 2,3-dioxygenase 1 (IDO1) inhibition

e14103

Background: Anti-PD1 inhibitors are effective in only a subset of lung cancers, and many that respond later develop resistance. We recently found in a mouse model of anti-PD1 resistance that tumor-infiltrating lymphocytes (TILs) overexpressed indoleamine 2,3-dioxygenase 1 (IDO1), a rate-limiting step in the catabolism of tryptophan (Trp) to kynurenine (Kyn) often implicated in immunosuppression. We tested whether inhibiting IDO would affect anti-PD1 mediated resistance. Methods: We used our anti-PD1-resistant lung cancer model (344SQ_R), which involved treating the parental 344SQ cells (344SQ_P) with anti-PD1 antibody followed by passage in 129SV/ev mice. We treated 344SQ_P and 344SQ_R mice with or without a selective IDO1 inhibitor (INCB023843) and measured tumor growth and lung metastasis. Plasma Trp and Kyn levels were tested by liquid chromatography–tandem mass spectrometry. TILs from blood and tumor-draining lymph nodes were isolated, analyzed by flow cytometry, and RNA was extracted for qPCR. Plasma C-C motif chemokine 22 (CCL22) levels were tested by ELISA. Data were analyzed with Prism 5.0 (GraphPad Software) and Flowjo V-10. Results: In untreated mice, IDO1 expression was 12 times higher in TILs from 344SQ_R mice than 344SQ_P mice, and mean plasma Kyn and Kyn/Trp levels were 3 times higher in 344SQ_R than in 344SQ_P. IDO inhibition was effective only in the PD1-resistant mice, reducing both tumor growth and lung metastasis. A subpopulation of myeloid-derived suppressor cells (Gr1int/lo CD11b+F4/80+) showed the greatest increase in IDO1 expression when comparing 344SQ_R to 344SQ_P and decreased after INCB023843 treatment only in 344SQ_R. INCB023843 also increased infiltrating CD8+ T cells, decreased CCL22 and regulatory T cells only in 344SQ_R tumors. Conclusions: Our results suggest that IDO1 is overexpressed in TILs from tumors resistant to anti-PD1 therapy; that a high plasma Kyn/Try ratio may be a marker of anti-PD1 resistance; and that IDO1 inhibition could be a promising approach for treating lung cancer that does not respond to anti-PD1 therapy.

Fatty-acid-binding proteins as a novel target for the treatment of anti-PD-1-resistant tumors

11562

Background: The mechanisms underlying immunosuppression and resistance to PD1 inhibitors in cancer are not well understood. We attempted to fill this gap with an integrated transcriptome analysis in an anti-PD1-resistant lung adenocarcinoma mouse model. The model was created by in vivo passage of 344SQ murine lung cancer cells (p53R172HΔg/+K-rasLA1/+) in a syngeneic host repeatedly dosed with anti-mouse PD1 antibodies. Anti-PD1-resistant 344SQ (344SQ_R) and 344SQ parental (344SQ_P) cells were then inoculated into syngeneic 129Sv/ev mice, which were then dosed twice with anti-PD1 or control IgG antibodies. Methods: Tumor tissues were collected and analyzed as follows: transcriptome with Affymetrix; protein levels by reverse phase protein array analysis; signature enrichment by gene set enrichment analysis; metabolome by mass spectrometry; and lipid content with fluorescent probes Oil O and BODIPY. We also isolated tumor-infiltrating immune cells for flow cytometry and gene expression analyses. Results: We identified lipid-related metabolic pathways as being the most highly enriched in anti-PD1-resistant tumors (344SQ_R) vs. their 344SQ_P counterparts; the resistant cells also had more lipid droplets than the 344SQ_P cells. The anti-PD1-resistant tumors overexpressed several genes involved in lipogenesis and fatty acid pathways, including fatty acid binding proteins (FABPs). Specifically, FABP overexpression promoted fatty acid uptake and lipid-droplet accumulation in resistant tumors. 344SQ_R tumors promoted immune suppressive cells by upregulating FABPs expression in M2-like macrophages, marked by increased fatty acid intake and fatty acid oxidation. Conversely, percentages of CD4+ and CD8+ tumor-infiltrating lymphocytes were reduced in the resistant tumors. Conclusions: These results suggest that lipid metabolic rewiring drives resistance PD1 inhibitors supporting the accumulation of immunosuppressive cells, including M2-like macrophages, preventing type I immune responses elicited by T cells. Collectively, these findings reveal new potential lipid-related targets for drug development or new treatments combining inhibitors of these targets with anti-PD1 therapy.

Optimizing Radiotherapy with Immunotherapeutic Approaches

Several factors must be considered to successfully integrate immunotherapy with radiation into clinical practice. One such factor is that concepts arising from preclinical work must be tested in combination with radiation in preclinical models to better understand how combination therapy will work in patients; examples include checkpoint inhibitors, tumor growth factor-beta (TGF-β) inhibitors, and natural killer (NK) cell therapy. Also, many radiation fields and fractionation schedules typically used in radiation therapy had been standardized before the introduction of advanced techniques for radiation planning and delivery that account for changes in tumor size, location, and motion during treatment, as well as uncertainties introduced by variations in patient setup between treatment fractions. As a result, radiation therapy may involve the use of large treatment volumes, often encompassing nodal regions that may not be irradiated with more conformal techniques. Traditional forms of radiation in particular pose challenges for combination trials with immunotherapy. This chapter explores these issues in more detail and provides insights as to how radiation therapy can be optimized to combine with immunotherapy.

Suppression of Type I IFN Signaling in Tumors Mediates Resistance to Anti-PD-1 Treatment That Can Be Overcome by Radiotherapy

Immune checkpoint therapies exhibit impressive efficacy in some patients with melanoma or lung cancer, but the lack of response in most cases presses the question of how general efficacy can be improved. In addressing this question, we generated a preclinical tumor model to study anti-PD-1 resistance by in vivo passaging of Kras-mutated, p53-deficient murine lung cancer cells (p53^R172HΔg/+K-ras^LA1/+ ) in a syngeneic host exposed to repetitive dosing with anti-mouse PD-1 antibodies. PD-L1 (CD274) expression did not differ between the resistant and parental tumor cells. However, the expression of important molecules in the antigen presentation pathway, including MHC class I and II, as well as β2-microglobulin, were significantly downregulated in the anti-PD-1-resistant tumors compared with parental tumors. Resistant tumors also contained fewer CD8⁺ (CD8α) and CD4⁺ tumor-infiltrating lymphocytes and reduced production of IFNγ. Localized radiotherapy induced IFNβ production, thereby elevating MHC class I expression on both parental and resistant tumor cells and restoring the responsiveness of resistant tumors to anti-PD-1 therapy. Conversely, blockade of type I IFN signaling abolished the effect of radiosensitization in this setting. Collectively, these results identify a mechanism of PD-1 resistance and demonstrate that adjuvant radiotherapy can overcome resistance. These findings have immediate clinical implications for extending the efficacy of anti-PD-1 immune checkpoint therapy in patients. Cancer Res; 77(4); 839-50. ©2016 AACR.

Strategies for combining immunotherapy with radiation for anticancer therapy

Radiation therapy controls local disease but also prompts the release of tumor-associated antigens and stress-related danger signals that primes T cells to promote tumor regression at unirradiated sites known as the abscopal effect. This may be enhanced by blocking inhibitory immune signals that modulate immune activity through a variety of mechanisms. Indeed, abscopal responses have occurred in patients with lung cancer or melanoma when given anti-CTLA4 antibody and radiation. Other approaches involve expanding and reinfusing T or NK cells or engineered T cells to express receptors that target specific tumor peptides. These approaches may be useful for immunocompromised patients receiving radiation. Preclinical and clinical studies are testing both immune checkpoint-based strategies and adoptive immunotherapies with radiation.

Uncovering the immune tumor microenvironment in non-small cell lung cancer to understand response rates to checkpoint blockade and radiation

The study of immunology has led to breakthroughs in treating non-small cell lung cancer (NSCLC). The recent approval of an anti-PD1 checkpoint drug for NSCLC has generated much interest in novel combination therapies that might provide further benefit for patients. However, a better understanding of which combinations may (or may not) work in NSCLC requires understanding the lung immune microenvironment under homeostatic conditions and the changes in that microenvironment in the setting of cancer progression and with radiotherapy. This review provides background information on immune cells found in the lung and the prognostic significance of these cell types in lung cancer. It also addresses current clinical directions for the combination of checkpoint inhibitors with radiation for NSCLC.