Abstract The association of Poly (ADP-ribose) polymerase (PARP) inhibitors with radiotherapy (RT) increase RT-induced DNA damage and radiosensitize tumors regardless deficiency in DNA repair pathways. Although PARP1 is the main protein responsible for PARP-mediated DNA repair, all first-generation PARP inhibitors act on both PARP1 and PARP2, which the latter is associated with hematological toxicity. The RT ability to induce DNA damage can be influenced by the radiation linear energy transfer (LET). High-LET radiation, such as alpha particles (LET: 60-200 keV/μm), induces more complex DNA damage than does low-LET radiation (photon, LET: 0.2 keV/μm). Thus, high-LET radiation combined with selective PARP1 inhibitors may be a promising strategy to radiosensitize tumors. The purpose of this study was to investigate if the selective PARP1 inhibition could radiosensitize BRCA1 mutant and wild-type triple-negative breast cancers (TNBC) to photons and alpha particles. The radiosensitization effect in vitro was assessed using TNBC cells: MDA-MB-436 (BRCA1 mutated), and its isogenic pair with BRCA1 recovered, MDA-MB-436 BRCA1, and 4T1. The IC50 of the PARP1 selective inhibitor (AZD5305) was determined across all cell lines by the clonogenic assay, and concentrations of AZD5305 that did not affect the colony formation ability without radiation were chosen for the radiopotentiation evaluation (clonogenic assay). Mice were inoculated with 4T1 cells in the hind leg. Diffusing Alpha-emitter Radiation Therapy (Alpha DaRT) was used to deliver alpha particles intratumorally, by the implantation of 224Ra-loaded sources. AZD5305 (1 mg/kg) was daily administered by oral gavage for 6 consecutive days, starting 24 h before Alpha DaRT implantation. Tumor growth delay and survival were assessed. AZD5305 significantly radiosensitized all the evaluated cell lines in vitro. AZD5305 alone (mice implanted with inert seeds) did not affect the tumor growth in mice (p=0.12) in comparison with inert+vehicle. Alpha DaRT delayed tumor growth in comparison with mice treated with inert+vehicle (p=0.03), but the Alpha DaRT+AZD5305 reduced tumor growth in comparison with Alpha DaRT+vehicle (p=0.05). Alpha DaRT promoted a non-significant (p=0.09) increase in survival when compared with inert+vehicle, but Alpha DaRT+AZD5305 increased survival in comparison with inert+vehicle (p=0.002), and Alpha DaRT+vehicle (p=0.06). Our findings demonstrate that AZD5305 significantly radiosensitizes TNBC to photons and alpha particles, regardless of the homologous recombination proficiency status. These results are novel because there no studies investigating selective PARP1 inhibition in combination with photons and alpha particles. Our work is relevant because the combination of AZD5305 with Alpha DaRT offers a promising strategy to minimize the adverse effects of PARP inhibition. AZD5305 presents less off-target effects than non-selective PARP inhibitors, while Alpha DaRT delivers alpha particles directly into the tumor, limiting radiosensitization of normal tissue. Citation Format: Poliana C. Marinello, Marco Tulio Freitas Reis, Walison Augusto Da Silva Brito, Amy Wu, Alexandre Rubinstein, Mark D. Wasley, Mandira Manandhar, Scott J. Bright, Yogesh Rai, Seyed Mojtaba Hosseini Ghahfarokhi, Ronen Segal, Vered Domankevich, Gabriel O. Sawakuchi. PARP1 selective inhibition sensitize triple-negative breast cancers to photon and alpha-particle therapy regardless of homologous recombination proficiency status. [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Translating Targeted Therapies in Combination with Radiotherapy; 2025 Jan 26-29; San Diego, CA. Philadelphia (PA): AACR; Clin Cancer Res 2025;31(2_Suppl):Abstract nr A010.

Pancreatic cancers (PC) are characterized by their aggressiveness, radioresistance, and immunologically "cold" nature, making them the third leading cause of cancer deaths in the US. Specifically, conventional radiotherapy approaches are limited by collateral damage to adjacent organs. Given the lack of effective treatments, this study investigates a novel therapy combining α-particle radiation through Diffusing Alpha-emitters Radiation Therapy (Alpha DaRT), an intratumoral source that releases alpha emitting atoms into the tumor microenvironment, with ATR inhibition (ATRi) to sensitize immunologically cold PC to anti-CTLA-4 (aCTLA-4). While conventional low linear energy transfer (LET) radiation (0.2 keV/μm) has lower capacity to induce double-strand breaks (DSBs), higher LET α-particles (70-200 keV/μm) generate more complex DSBs and micronuclei, activating an immune response through the cGAS-STING pathway. By combining Alpha DaRT with ATRi, we aim to impair radiation-induced DSB repair and checkpoint arrest, forcing mitotic progression despite unrepaired DNA damage, overstimulating this pathway. We hypothesize that the triple treatment (Alpha DaRT+ATRi+aCTLA-4) sensitizes immunologically cold tumors to aCTLA-4, delaying tumor growth, inducing tumor regression, and extending survival. Mice were implanted with 5 × 105 KPC cells subcutaneously in the left leg. After 7 days of tumor inoculation (day 0), Alpha DaRT sources were implanted. ATRi (or DMSO) was administered via oral gavage on days 0, 1, 2, 7, 8, and 9, at 75 mg/kg. Anti-CTLA-4 (or IgG) was delivered intraperitoneally on days 3, 6, 9, and 12. Tumor volumes were measured three times/week and mice were randomized into eight experimental groups, ranging from triple control to triple treatment. Tumor development was assessed according to tumor volume fold change, relative to Alpha DaRT insertion day. Both Alpha DaRT +ATRi or Alpha DaRT+aCTLA4 significantly reduced tumor development vs. monotherapies. Remarkably, more than 40% achieved complete tumor regression in the Alpha DaRT+DMSO+aCTLA-4 or Alpha DaRT+ATRi+aCTLA-4. Mice in which tumors regressed were re-challenged on day 130 with 5 × 105 KPC cells. Both the double treatment (Alpha DART + aCTLA4) or the triple treatment exhibited significantly smaller tumor development relative to naïve mice. These novel results suggest that the dual combination Alpha DaRT and aCTLA4 or the triple combination Alpha DaRT, ATRi, and aCTLA-4 may be a strategy to induce a robust and long-lasting immune activation in immunologically cold PC. Marco Reis, Poliana Marinello, Alexandre Rubinstein, Mark Wasley, Walison Brito, Ronen Sega, Vered Bachar, Gabriel Sawakuchi. Diffusing alpha-emitters radiation therapy in combination with anti-CTLA-4, as well as combination with both ATR inhibitor, and anti-CTLA-4 achieves long-lasting tumor regression in murine pancreatic cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 6154.

Abstract Background: Recently, the successful integration of immunotherapy with other treatment modalities has demonstrated its efficacy in enhancing immune activation and suppressing tumors in solid cancers. The most promising of such efforts include the use of low dose radiation (LD-XRT) to prime the tumor microenvironment and enhance the T cell infiltration and activation [Barsoumian HB, et al., 2020; Patel RR, et al., 2021; He K, et al., 2023]. With these advancements, there is an urgent need to develop clinical biomarkers to predict response and optimize treatment decisions. Recent evidence underscores the importance of nanomechanical alterations within the tumor microenvironment as mechanistic indicators of aggressiveness [Plodinec M, et al., 2012]. This study aims to demonstrate the value of ARTIDIS nanomechanical signature as early predictor of elucidate of response to combination LD-XRT/immune checkpoint inhibitors (ICI). Our measurement protocol in mice follows the same settings for biopsies acquired in routine biopsy collection protocol, thus supporting prompt clinical translation and integration. Methods: We established a mouse model of 344SQ lung adenocarcinoma tumors that exhibited resistance to anti-PD1 treatment in 129Sv/Ev mice. These mice underwent treatment protocols involving a combination of anti-PD1 and anti-CTLA4 antibodies, both with and without LD-XRT pre-treatment. Throughout the study, we closely monitored survival rates and tumor growth across diverse experimental groups. Employing the ARTIDIS platform, a cutting-edge technology that integrates atomic force microscopy with proprietary artificial intelligence algorithms, we extracted a multiparametric nanomechanical signature and we evaluated its outcome prediction value. This signature was then complemented by histopathology, multiplex immunofluorescence, and Nanostring assays to elucidate mechanisms of stroma remodulation and immune infiltration. Results: This study identifies the unique nanomechanical signature predictive of response to immunotherapy alone or in combination with radiation. Using the tissue nanomechanical signature as a predictive biomarker, we achieved precise differentiation between responders and non-responders, boasting a 90% sensitivity, 99.1% specificity, and a 96% AUC. To our knowledge, this study is the first to demonstrate the response-predicting power of a tissue derived nanomechanical signature for immune checkpoint inhibitors administered in combination with LD-XRT. These findings support clinical translation of the ARTIDIS nanomechanical signature as a pivotal tool for clinically predicting and evaluating responses to integrated radiation and immunotherapy approaches. Citation Format: Gitika Srivastava, Sara Nizzero, Mark Wasley, Mingee Kim, Kathleen Graham, Papa Diogop Ndiaye, Mariam Gachechiladze, Nahum Puebla-Osorio, Philipp Oertle, Tobias Appenzeller, Vittorio Cristini, Marko Loparic, Marija Plodinec, James W. Welsh. Tissue nanomechanics as a novel, clinically translatable predictive early biomarker of response in combination immunotherapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1178.

Background Low-dose radiation therapy (LD-RT) in combination with immune checkpoint inhibition (ICI) and/or cell therapy has emerged as an effective mediator to restore immune response in solid tumors. However, clinically available biomarkers still fail to effectively predict response and optimize therapy choices. Emerging evidence indicates that nanomechanical alterations of the tumor microenvironment are viable predictors of aggressiveness. We hypothesized that the benefit of LD-RT lies not only in immune activating, but also stromal and tumor nanomechanical remodulation by LD-RT. In this work we have investigated the nanomechanical signature of tumor response to LD-RT combined with immunotherapy, to study nanomechanical drivers of immune infiltration, and how they can be used to optimize cancer diagnosis and orientate therapy choice. Methods For the ICI study, 344SQ lung adenocarcinoma tumors resistant to anti-PD1 treatment were established in 129Sv/Ev mice. Mice were treated with a combination of anti-PD1 and anti-CTLA4 antibodies, with and without LD-RT pre-treatment. For the cell therapy study NSG mice were implanted with gastric carcinoma cells. Both low dose and high dose RT were used in combination with cell therapy. Survival and tumor growth were monitored for the various groups. Tumor biopsies were collected at early time points and at the end of each experiment. All tissues were examined via the ARTIDIS platform, to extract a multiparametric nanomechanical signature. The ARTIDIS technology used, combines atomic force microscopy with artificial intelligence proprietary algorithms to provide accurate and reliable characterization of the nanomechanical properties of cancer tissue. We also performed histopathology, multiplex immunofluorescence and Nanostring analyses to characterize stroma remodulation and immune infiltration. Results In both studies we have identified a clear signature of radiation – induced enhanced response to immunotherapy, in the nanomechanical parameter space. In the radiation dataset we achieved almost perfect separation of responders vs non responders, with 90% sensitivity, 99.1% specificity and 96% AUC. In the cell therapy dataset, we can clearly detect the signature of T cell infiltration post radiation, with 92% sensitivity, 100% specificity and 95% accuracy, and this is valid across different doses of T cell infused and for both low and high dose radiation. Conclusions In these studies, we demonstrated for the first time a clear nanomechanical signature of LD-RT-mediated response to both immune checkpoint inhibitors and cell therapy in two different mouse models. Our findings open the way to using ARTIDIS nanomechanical signature as a clinically translatable predictor of response to combination radiation and immunotherapies. Ethics Approval All mouse studies were conducted in accordance with guidelines from the M.D. Anderson Institutional Animal Care and Use Committee (IACUC).

Abstract Diverse factors contribute to the limited clinical response to radiotherapy (RT) and immunotherapy in metastatic non–small cell lung cancer (NSCLC), among which is the ability of these tumors to recruit a retinue of suppressive immune cells—such as M2 tumor-associated macrophages (TAM)—thereby establishing an immunosuppressive tumor microenvironment that contributes to tumor progression and radio resistance. M2 TAMs are activated by the STAT6 signaling pathway. Therefore, we targeted STAT6 using an antisense oligonucleotide (ASO) along with hypofractionated RT (hRT; 3 fractions of 12 Gy each) to primary tumors in three bilateral murine NSCLC models (Lewis lung carcinoma, 344SQ-parental, and anti–PD-1–resistant 344SQ lung adenocarcinomas). We found that STAT6 ASO plus hRT slowed growth of both primary and abscopal tumors, decreased lung metastases, and extended survival. Interrogating the mechanism of action showed reduced M2 macrophage tumor infiltration, enhanced TH1 polarization, improved T-cell and macrophage function, and decreased TGFβ levels. The addition of anti–PD-1 further enhanced systemic antitumor responses. These results provide a preclinical rationale for the pursuit of an alternative therapeutic approach for patients with immune-resistant NSCLC.

Tumors deploy various immune-evasion mechanisms that create a suppressive environment and render effector T-cells exhausted and inactive. Therefore, a rational utilization of checkpoint inhibitors may alleviate exhaustion and may partially restore antitumor functions. However, in high-tumor-burden models, the checkpoint blockade fails to maintain optimal efficacy, and other interventions are necessary to overcome the inhibitory tumor stroma. One such strategy is the use of radiotherapy to reset the tumor microenvironment and maximize systemic antitumor outcomes. In this study, we propose the use of anti-PD1 and anti-TIGIT checkpoint inhibitors in conjunction with our novel RadScopal technique to battle highly metastatic lung adenocarcinoma tumors, bilaterally established in 129Sv/Ev mice, to mimic high-tumor-burden settings. The RadScopal approach is comprised of high-dose radiation directed at primary tumors with low-dose radiation delivered to secondary tumors to improve the outcomes of systemic immunotherapy. Indeed, the triple therapy with RadScopal + anti-TIGIT + anti-PD1 was able to prolong the survival of treated mice and halted the growth of both primary and secondary tumors. Lung metastasis counts were also significantly reduced. In addition, the low-dose radiation component reduced TIGIT receptor (PVR) expression by tumor-associated macrophages and dendritic cells in secondary tumors. Finally, low-dose radiation within triple therapy decreased the percentages of TIGIT+ exhausted T-cells and TIGIT+ regulatory T-cells. Together, our translational approach provides a new treatment alternative for cases refractory to other checkpoints and may bring immunotherapy into a new realm of systemic disease control.

Abstract Background While improvements in immunoradiotherapy have significantly improved outcomes for cancer patients, this treatment approach has nevertheless proven ineffective at controlling the majority of malignancies. One of the mechanisms of resistance to immunoradiotherapy is that immune cells may be suppressed via the myriad of different immune checkpoint receptors. Therefore, simultaneous blockade of multiple immune checkpoint receptors may enhance the treatment efficacy of immunoradiotherapy. Methods We combined NBTXR3-enhanced localized radiation with the simultaneous blockade of three different checkpoint receptors: PD1, LAG3, and TIGIT, and tested the treatment efficacy in an anti-PD1-resistant lung cancer model in mice. 129 Sv/Ev mice were inoculated with fifty thousand αPD1-resistant 344SQR cells in the right leg on day 0 to establish primary tumors and with the same number of cells in the left leg on day 4 to establish the secondary tumors. NBTXR3 was intratumorally injected into the primary tumors on day 7, which were irradiated with 12 Gy on days 8, 9, and 10. Anti-PD1 (200 µg), αLAG3 (200 µg), and αTIGIT (200 µg) were given to mice by intraperitoneal injections on days 5, 8, 11, 14, 21, 28, 35, and 42. Results This nanoparticle-mediated combination therapy is effective at controlling the growth of irradiated and distant unirradiated tumors, enhancing animal survival, and is the only one that led to the destruction of both tumors in approximately 30% of the treated mice. Corresponding with this improved response is robust activation of the immune response, as manifested by increased numbers of immune cells along with a transcriptional signature of both innate and adaptive immunity within the tumor. Furthermore, mice treated with this combinatorial therapy display immunological memory response when rechallenged by the same cancer cells, preventing tumor engraftment. Conclusion Our results strongly attest to the efficacy and validity of combining nanoparticle-enhanced radiotherapy and simultaneous blockade of multiple immune checkpoint receptors and provide a pre-clinical rationale for investigating its translation into human patients. Graphical Abstract

Radiotherapy (RT) has been used to control tumors by physically damaging DNA and inducing apoptosis; it also promotes antitumor immune responses via neoantigens release and augmenting immune-oncology agents to elicit systemic response. Tumor regression after RT can recruit inflammatory cells, such as tumor-associated macrophages and CD11b+ myeloid cell populations, a major subset of which may actually be immunosuppressive. However, these inflammatory cells also express Toll-like receptors (TLRs) that can be stimulated to reverse suppressive characteristics and promote systemic antitumor outcomes. Here, we investigated the effects of adding CMP-001, a CpG-A oligodeoxynucleotide TLR9 agonist delivered in a virus-like particle (VLP), to RT in two murine models (344SQ metastatic lung adenocarcinoma and CT26 colon carcinoma). High-dose RT (12Gy x 3 fractions) significantly increased the percentages of plasmacytoid dendritic cells within the tumor islets 3- and 5-days post-RT; adding CMP-001 after RT also enhanced adaptive immunity by increasing the proportion of CD4+ and CD8+ T cells. RT plus CMP-001-mediated activation of the immune system led to significant inhibition of tumor growth at both primary and abscopal tumor sites, thereby suggesting a new combinatorial treatment strategy for systemic disease.

BackgroundTIGIT and LAG3 are inhibitory receptors expressed on cytotoxic CD8+ T cells and NK cells and directly inhibit the activation and proliferation of these cells. We proposed that blockade of TIGIT and LAG3 could improve antitumor immune response in a mouse model of anti-PD1 (aPD1)-resistant mice.Methods129Sv/Ev mice were inoculated with 50,000 aPD1-resistant 344SQR cells in the right leg on day 0 (primary tumor) and with 50,000 cells in the left leg on day 4 (secondary tumor). Primary tumors were injected with NBTXR3 radioenhancer nanoparticles on day 7 and irradiated with 12 Gy on days 8, 9, and 10. Anti-PD1, aLAG3, and aTIGIT were given to mice by intraperitoneal injections on days 5, 8, 11, 14, 21, 28, 35, and 42. On day 21, primary tumors, secondary tumors, and blood samples were harvested and analyzed with flow cytometry to evaluate changes in immune cell populations. The RNA extracted from the tumors were also analyzed by Nanostring. Mice in which tumors were completely eradicated were re-challenged with another 50,000 344SQR cells in the right flank at least two months post radiation; no further treatment was given to these mice, and tumor growth was monitored.ResultsThe addition of aTIGIT, aLAG3, or aTIGIT+aLAG3 to NBTXR3+XRT+aPD1 therapy significantly improved control of tumors, and the addition of aTIGIT+aLAG3 also led to fewer spontaneous lung metastases. The addition of either aTIGIT or aLAG3 to NBTXR3+XRT+aPD1 extended mouse survival time relative to NBTXR3+XRT+aPD1. None of the 8 mice in either the NBTXR3+XRT+aPD1+aTIGIT group or the NBTXR3+XRT+aPD1+aLAG3 group survived more than 32 days; in contrast, 3 of the 8 mice that received NBTXR3+XRT+aPD1+aTIGIT+aLAG3 survived until the end of the experiment. These surviving mice were found to have developed memory against 344SQR cells, and no further tumor growth was observed after re-challenge. Flow cytometry analysis showed that adding aTIGIT+aLAG3 to NBTXR3+XRT+aPD1 increased the percentages of proliferating CD8+ T cells in primary tumors, secondary tumors, and blood. Furthermore, Nanostring transcriptomic analysis of cells isolated from the tumors of mice thus treated showed evidence of classical two-step immunological priming, with an elevation of innate immune genes at the primary tumor and full-blown activation of the immune system within the secondary tumor.ConclusionsBlockade of TIGIT and LAG3 with NBTXR3+XRT+aPD1 improved CD8+ T-cell proliferation, augmented the antitumor response at both irradiated and unirradiated (abscopal) tumors, and induced potent long-term antitumor memory in mice.AcknowledgementsThis work was supported by Cancer Center Support (Core) Grant CA016672 to The University of Texas MD Anderson Cancer Center; the Goodwin family research fund; the family of M. Adnan Hamed and the Orr Family Foundation to MD Anderson Cancer Center‘s Thoracic Radiation Oncology program; an MD Anderson Knowledge Gap award; Nanobiotix.

Purpose: Radiation combined with PD1 blockade offers significant treatment benefits in several tumor types; however, anti-PD1 resistance precludes such benefits in many cases. Here we attempted to overcome anti-PD1 resistance by combining localized radiation with a radioenhancing nanoparticle (NBTXR3) and systemic anti-PD1 treatment to achieve abscopal effects in an anti-PD1-resistant mouse model of lung cancer. Methods and Materials: Female 129Sv/Ev mice were inoculated with 344SQ anti-PD1-resistant (344SQR) or anti-PD1-sensitive (344SQP) metastatic lung cancer cells in the right leg on day 0 ("primary" tumor) and the left leg on day 4 ("secondary" tumor). Primary tumors were injected intratumorally with NBTXR3 on day 7 and were irradiated with 12 Gy on days 8, 9, and 10. Mice were given 6 intraperitoneal injections of anti-PD1. T cell receptor repertoire was analyzed in tumor samples with RNA sequencing, infiltration of CD8 T cells with immunohistochemical staining, and activities of various immune pathways with NanoString analysis. Results: The triple combination of NBTXR3 with localized radiation and systemic anti-PD1 significantly delayed the growth of both irradiated and unirradiated tumors in both 344SQP and 344SQR tumor models. NBTXR3 remodeled the immune microenvironment of unirradiated tumors by triggering the activation of various immune pathways, increasing the number of CD8+ T cells, and modifying the T cell receptor repertoire in the 344SQR tumor model. Conclusions: The ability of NBTXR3 to evoke significant abscopal effects in both anti-PD1-sensitive and anti-PD1-resis-tant lung cancers could open the possibility of its use for treating patients with metastatic lung cancer regardless of sensitivity (or resistance) to immunotherapies. (C) 2021 Published by Elsevier Inc.

Background Combining radiotherapy with PD1 blockade has had impressive antitumor effects in preclinical models of metastatic lung cancer, although anti-PD1 resistance remains problematic. Here, we report results from a triple-combination therapy in which NBTXR3, a clinically approved nanoparticle radioenhancer, is combined with high-dose radiation (HDXRT) to a primary tumor plus low-dose radiation (LDXRT) to a secondary tumor along with checkpoint blockade in a mouse model of anti-PD1-resistant metastatic lung cancer. Methods Mice were inoculated with 344SQR cells in the right legs on day 0 (primary tumor) and the left legs on day 3 (secondary tumor). Immune checkpoint inhibitors (ICIs), including anti-PD1 (200 μg) and anti-CTLA4 (100 μg) were given intraperitoneally. Primary tumors were injected with NBTXR3 on day 6 and irradiated with 12-Gy (HDXRT) on days 7, 8, and 9; secondary tumors were irradiated with 1-Gy (LDXRT) on days 12 and 13. The survivor mice at day 178 were rechallenged with 344SQR cells and tumor growth monitored thereafter. Results NBTXR3 + HDXRT + LDXRT + ICIs had significant antitumor effects against both primary and secondary tumors, improving the survival rate from 0 to 50%. Immune profiling of the secondary tumors revealed that NBTXR3 + HDXRT + LDXRT increased CD8 T-cell infiltration and decreased the number of regulatory T (Treg) cells. Finally, none of the re-challenged mice developed tumors, and they had higher percentages of CD4 memory T cells and CD4 and CD8 T cells in both blood and spleen relative to untreated mice. Conclusions NBTXR3 nanoparticle in combination with radioimmunotherapy significantly improves anti-PD1 resistant lung tumor control via promoting antitumor immune response. Graphical Abstract

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

BackgroundThis study compared response rates and outcomes of combined radiotherapy and immunotherapy (iRT) based on the type of checkpoint inhibitor (anti-cytotoxic T-lymphocyte-associated protein 4 (CTLA4) vs antiprogrammed death-1 (PD1)) for metastatic non-small cell lung cancer (mNSCLC).MethodsWe retrospectively reviewed two prospective trials of radiation combined with anti-CTLA4 or anti-PD1 for patients with mNSCLC. Patients undergoing non-salvage stereotactic body radiation therapy (SBRT) to lung sites were selected from both trials and grouped by the immunotherapeutic compound received. Endpoints included in-field and out-of-field response rates, and overall response rate (complete or partial response) (all by response evaluation criteria in solid tumors). Progression-free survival (PFS) and overall survival (OS) were estimated with the Kaplan-Meier method.ResultsMedian follow-up times for the 33 patients (n=17 SBRT+anti-CTLA4, n=16 SBRT+anti-PD1) were 19.6 and 19.9 months. Response rates for out-of-field lesions were similar between anti-PD1 (37%) and anti-CTLA4 (24%) (p=0.054). However, global response rates for all lesions were 24% anti-CTLA4 vs 56% anti-PD1 (p=0.194). The PFS was 76% for anti-CTLA4 vs 94% anti-PD1 at 3 months, 52% vs 87% at 6 months, 31% vs 80% at 12 months, and 23% vs 63% at 18 months (p=0.02). Respective OS values were 76% vs 87% at 6 months, 47% vs 80% at 12 months, and 39% vs 66% at 18 months (p=0.08).ConclusionsBoth anti-CTLA4 and anti-PD1 agents prompt a similar degree of in-field and out-of-field responses after iRT, although the global response rate and PFS were statistically higher in the anti-PD1 cohort. Further dedicated study and biological mechanistic assessment is required.Trial registration numbersNCT02239900 and NCT02444741.

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.