P1.15-004 An Open-Label, Multitumor Phase II Basket Study of Olaparib and Durvalumab (MEDIOLA): Results in Patients with Relapsed SCLC

Beyond monotherapy: An era ushering in combinations of PARP inhibitors with immune checkpoint inhibitors for solid tumors

The introduction of PARP inhibitors (PARPis) and immune checkpoint inhibitors (ICIs) has marked a significant shift in the treatment landscape for solid tumors. Emerging preclinical evidence and initial clinical trials have indicated that the synergistic application of PARPis and ICIs may enhance treatment efficacy and potentially improve long-term patient outcomes. Nonetheless, how to identify specific tumor types and molecular subgroups most likely to benefit from this combination remains an area of ongoing research. This review thoroughly examines current studies on the co-administration of PARPis and ICIs across various solid tumors. It explores the underlying mechanisms of action, evaluates clinical efficacy, identifies potential responder populations, and delineates common adverse events alongside strategic management approaches. The aim is to offer a detailed understanding of this combination therapy, potentially guiding future therapeutic strategies for solid tumors.

Promises of Protein Kinase Inhibitors in Recalcitrant Small-Cell Lung Cancer: Recent Scenario and Future Possibilities

SCLC is refractory to conventional therapies; targeted therapies and immunological checkpoint inhibitor (ICI) molecules have prolonged survival only marginally. In addition, ICIs help only a subgroup of SCLC patients. Different types of kinases play pivotal roles in therapeutics-driven cellular functions. Therefore, there is a significant need to understand the roles of kinases in regulating therapeutic responses, acknowledge the existing knowledge gaps, and discuss future directions for improved therapeutics for recalcitrant SCLC. Here, we extensively review the effect of dysregulated kinases in SCLC. We further discuss the pharmacological inhibitors of kinases used in targeted therapies for recalcitrant SCLC. We also describe the role of kinases in the ICI-mediated activation of antitumor immune responses. Finally, we summarize the clinical trials evaluating the potential of kinase inhibitors and ICIs. This review overviews dysregulated kinases in SCLC and summarizes their potential as targeted therapeutic agents. We also discuss their clinical efficacy in enhancing anticancer responses mediated by ICIs.

Biomarker-driven phase 2 umbrella trial: Clinical efficacy of olaparib monotherapy and combination with ceralasertib (AZD6738) in small cell lung cancer

BACKGROUND

Based on a high incidence of genomic alteration in the cell cycle and DNA damage and response (DDR)-related pathways in small cell lung cancer (SCLC), the clinical efficacy of the DDR-targeting agent olaparib (PARP inhibitor) as monotherapy and in combination with ceralasertib (ATR inhibitor) in relapsed or refractory SCLC was evaluated.

METHODS

As part of a phase 2 biomarker driven umbrella study, patients with SCLC and predefined DDR gene alterations who failed to benefit from prior platinum-based regimens were allocated to the olaparib monotherapy arm and nonbiomarker-selected patients were allocated to the olaparib and ceralasertib combination arm.

RESULTS

In the olaparib monotherapy arm (n = 15), the objective response rate was 6.7% (one partial response), and the disease control rate was 33.3%, including three patients with stable disease. The median progression-free survival was 1.3 months (95% CI, 1.2-NA). In the combination arm (n = 26), the objective response rate and disease control rate were 3.8% and 42.3%, respectively, with one partial response and 10 patients with stable disease. The median progression-free survival was 2.8 months (95% CI, 1.8-5.4). Treatment was generally well tolerated except for one fatal case of neutropenic fever in the combination arm.

CONCLUSIONS

Targeting DDR pathways with olaparib as a single agent or in combination with ceralasertib did not meet the predefined efficacy end point. However, disease stabilization was more evident in the combination arm. Further investigation of the combination of olaparib in SCLC should be performed with diverse combinations and patient selection strategies to maximize efficacy.

Systemic Therapy for Small-Cell Lung Cancer: ASCO-Ontario Health (Cancer Care Ontario) Guideline

PURPOSE

To provide evidence-based recommendations to practicing clinicians on the management of patients with small-cell lung cancer.

METHODS

An Expert Panel of medical oncology, thoracic surgery, radiation oncology, pulmonary, community oncology, research methodology, and advocacy experts were convened to conduct a literature search, which included systematic reviews, meta-analyses, and randomized controlled trials published from 1990 through 2022. Outcomes of interest included response rates, overall survival, disease-free survival or recurrence-free survival, and quality of life. Expert Panel members used available evidence and informal consensus to develop evidence-based guideline recommendations.

RESULTS

The literature search identified 95 relevant studies to inform the evidence base for this guideline.

RECOMMENDATIONS

Evidence-based recommendations were developed to address systemic therapy options, timing of therapy, treatment in patients who are older or with poor performance status, role of biomarkers, and use of myeloid-supporting agents in patients with small-cell lung cancer.Additional information is available at www.asco.org/thoracic-cancer-guidelines.

A signal-seeking Phase 2 study of olaparib and durvalumab in advanced solid cancers with homologous recombination repair gene alterations

PURPOSE

To determine the safety and efficacy of PARP plus PD-L1 inhibition (olaparib + durvalumab, O + D) in patients with advanced solid, predominantly rare cancers harbouring homologous recombination repair (HRR) defects.

PATIENTS AND METHODS

In total, 48 patients were treated with O + D, 16 with BRCA1/2 alterations (group 1) and 32 with other select HRR alterations (group 2). Overall, 32 (66%) patients had rare or less common cancers. The primary objective of this single-arm Phase II trial was a progression-free survival rate at 6 months (PFS6). Post hoc exploratory analyses were conducted on archival tumour tissue and serial bloods.

RESULTS

The PFS6 rate was 35% and 38% with durable objective tumour responses (OTR) in 3(19%) and 3(9%) in groups 1 and 2, respectively. Rare cancers achieving an OTR included cholangiocarcinoma, perivascular epithelioid cell (PEComa), neuroendocrine, gallbladder and endometrial cancer. O + D was safe, with five serious adverse events related to the study drug(s) in 3 (6%) patients. A higher proportion of CD38 high B cells in the blood and higher CD40 expression in tumour was prognostic of survival.

CONCLUSIONS

O + D demonstrated no new toxicity concerns and yielded a clinically meaningful PFS6 rate and durable OTRs across several cancers with HRR defects, including rare cancers.

Current Evidence and Future Perspectives about the Role of PARP Inhibitors in the Treatment of Thoracic Cancers

In recent years, poly (ADP-ribose) polymerase (PARP) inhibition has become a promising therapeutic option for several tumors, especially for those harboring a BRCA 1-2 mutation or a deficit in the homologous recombination repair (HRR) pathway. Nevertheless, to date, PARP inhibitors are still not largely used for thoracic malignancies neither as a single agent nor in combination with other treatments. Recently, a deeper understanding of HRR mechanisms, alongside the development of new targeted and immunotherapy agents, particularly against HRR-deficient tumors, traced the path to new treatment strategies for many tumor types including lung cancer and malignant pleural mesothelioma. The aim of this review is to sum up the current knowledge about cancer-DNA damage response pathways inhibition and to update the status of recent clinical trials investigating the use of PARP inhibitors, either as monotherapy or in combination with other agents for the treatment of thoracic malignancies. We will also briefly discuss available evidence on Poly(ADP-Ribose) Glycohydrolase (PARG) inhibitors, a novel promising therapeutic option in oncology.

Olaparib and durvalumab in patients with relapsed small cell lung cancer (MEDIOLA): An open-label, multicenter, phase 1/2, basket study

INTRODUCTION

Preclinical studies have demonstrated increased efficacy with combined DNA damage response inhibition and immune checkpoint blockade compared with either alone. We assessed olaparib in combination with durvalumab in patients with relapsed small cell lung cancer (SCLC).

METHODS

Patients with previously treated limited or extensive-stage SCLC received oral olaparib 300 mg twice daily, as run-in for 4 weeks, then with durvalumab (1500 mg intravenously every 4 weeks) until disease progression. Primary endpoints were safety, tolerability, and 12-week disease control rate (DCR). Secondary endpoints included 28-week DCR, objective response rate (ORR), duration of response, progression-free survival, overall survival, change in tumor size, and programmed death-ligand 1 (PD-L1) expression subgroup analyses.

RESULTS

Forty patients were enrolled and analyzed for safety; 38 were analyzed for efficacy. Eleven patients (28.9% [90% confidence interval (CI), 17.2-43.3]) had disease control at 12 weeks. ORR was 10.5% (95% CI, 2.9-24.8). Median progression-free and overall survival were 2.4 (95% CI, 0.9-3.0)months and 7.6(95% CI, 5.6-8.8)months, respectively. The most common adverse events (≥40.0%) were anemia, nausea, and fatigue. Grade ≥ 3 adverse events occurred in 32 patients (80.0%). PD-L1 levels, tumor mutational burden, and other genetic mutations were evaluated, but no significant correlations with clinical outcomes wereobserved.

CONCLUSIONS

Tolerability of olaparib with durvalumab was consistent with the safety profile of each agent alone. Although the 12-week DCR did not meet the prespecified target (60%), four patients responded, and median overall survival was promising for a pretreated SCLC population. Further analyses are required to identify patients most likely to benefit from this treatment approach.

Spotlight on Small-Cell Lung Cancer and Other Lung Neuroendocrine Neoplasms

Lung neuroendocrine neoplasms (NENs) encompass a spectrum of neoplasms that are subdivided into the well-differentiated neuroendocrine tumors comprising the low- and intermediate-grade typical and atypical carcinoids, respectively, and the poorly differentiated, high-grade neuroendocrine carcinomas including large-cell neuroendocrine carcinomas and small-cell lung carcinoma (SCLC). Here, we review the current morphological and molecular classifications of the NENs on the basis of the updated WHO Classification of Thoracic Tumors and discuss the emerging subclassifications on the basis of molecular profiling and the potential therapeutic implications. We focus on the efforts in subtyping SCLC, a particularly aggressive tumor with few treatment options, and the recent advances in therapy with the adoption of immune checkpoint inhibitors in the frontline setting for patients with extensive-stage SCLC. We further highlight the promising immunotherapy strategies in SCLC that are currently under investigation.

Combining inhibition of immune checkpoints and PARP: rationale and perspectives in cancer treatment

INTRODUCTION

Genomic instability resulting from the inability of cells to repair DNA damage is a breeding ground for immune checkpoint inhibitors (ICIs) and targeted treatments. Poly (ADP-ribose) polymerase inhibitors (PARPi) interfere with the efficient repair of DNA single-strand break damage inducing, mainly in tumors with existing defects in double strand DNA repair system, synthetic lethality.

AREAS COVERED

By amplifying the DNA damage and inducing immunogenic cell death PARPi leads tumor neoantigens to increase, upregulation of programmed death-ligand 1, and modulation of the tumor microenvironment facilitating a more intense antitumor immune response. In this review, we reported the immunological role of PARPi and the rational use of the combination with ICIs, evaluating data from combination clinical trials and discussing perspectives.

EXPERT OPINION

Several prospective combination studies to overcome existing limitations to PARPi and ICI single agents are currently ongoing. The identification of the different resistance mechanisms to PARPi and ICI as well as the development of accurate and predictive biomarkers of response should be a priority to identify the patients who may most benefit from this combination. Similarly, clarifying the role and interaction between the DNA damage repair pathways and the tumor immune microenvironment would increase success of the combination.

Immune Checkpoint Inhibitors and Chemoradiation for Limited-Stage Small Cell Lung Cancer

OPINION STATEMENT

Limited-stage small cell lung cancer (LS-SCLC) is a potentially curable disease. However, most patients develop disease relapse shortly after definitive treatment. The landmark trials IMpower133 and CASPIAN demonstrated a survival benefit with the addition of immunotherapy to first-line platinum/etoposide for extensive-stage small cell lung cancer. Therefore, it is critical to determine whether advancements in overall survival with immunotherapy can be translated earlier into the treatment paradigm for LS-SCLC. Decades of robust preclinical research into the synergism of radiation therapy and immunotherapy set the stage for the combination of these treatment modalities. Recently published data suggests tolerability of single agent immunotherapy concurrent with chemoradiation in LS-SCLC, along with promising efficacy. However, combination immunotherapy in the consolidation setting appears too toxic, although this may be reflective of the dosing schedule rather than inherent to any combination immune checkpoint blockade. Here, we review underlying mechanisms of synergy with the combination of radiation and immunotherapy, the safety and efficacy of respective treatment modalities, and the ongoing trials that are exploring novel therapeutic approaches for LS-SCLC. Pivotal trials in LS-SCLC are ongoing and anticipated to aid in understanding efficacy and safety of immunotherapy with concurrent platinum-based chemoradiotherapy.

Novel therapeutic combinations with PARP inhibitors for small cell lung cancer: A bench-to-bedside review

Small cell lung cancer (SCLC) is treated as a monolithic disease despite the evident intra- and intertumoral heterogeneity. Non-specific DNA-damaging agents have remained the first-line treatment for decades. Recently, emerging transcriptomic and genomic profiling of SCLC tumors identified distinct SCLC subtypes and vulnerabilities towards targeted therapeutics, including inhibitors of the nuclear enzyme poly (ADP-ribose) polymerase (PARPi). SCLC cell lines and tumors exhibited an elevated level of PARP1 protein and mRNA compared to healthy lung tissues and other subtypes of lung tumors. Notable responses to PARPi were also observed in preclinical SCLC models. Clinically, PARPi monotherapy exerted variable benefits for SCLC patients. To date, research is being vigorously conducted to examine predictive biomarkers of PARPi response and various PARPi combination strategies to maximize the clinical utility of PARPi. This narrative review summarizes existing preclinical evidence supporting PARPi monotherapy, combination therapy, and respective translation to the clinic. Specifically, we covered the combination of PARPi with DNA-damaging chemotherapy (cisplatin, etoposide, temozolomide), thoracic radiotherapy, immunotherapy (immune checkpoint inhibitors), and many other novel therapeutic agents that target DNA damage response, tumor microenvironment, epigenetic modulation, angiogenesis, the ubiquitin-proteasome system, or autophagy. Putative biomarkers, such as SLFN11 expression, MGMT methylation, E2F1 expression, and platinum sensitivity, which may be predictive of response to distinct therapeutic combinations, were also discussed. The future of SCLC treatment is undergoing rapid change with a focus on tailored and personalized treatment strategies. Further development of cancer therapy with PARPi will immensely benefit at least a subset of biomarker-defined SCLC patients.

Immunotherapy in Small Cell Lung Cancer Treatment: a Promising Headway for Future Perspective

OPINION STATEMENT

Despite advancements in clinical research, both prognosis and treatment for SCLC patients are still in the nascent stage. SCLC is a fatal disease with high tumor mutational burden and is strongly associated with exposure to tobacco. This leads to the development of potential neo-antigens, inhibition of immune responses, and development of paraneoplastic disorders. Surgery, radiation, and chemotherapy are widely accepted treatments for cancer globally, and most recently, immunotherapy has now become the "fourth pillar" of SCLC treatment. Various immune checkpoint pathways regulate the activation of T cells at multiple stages during an immune response. T cell checkpoint inhibitors such as anti-PD1 (pembrolizumab, nivolumab), anti-PDL1, and anti-CTLA-4 (tremelimumab, ipilimumab) have potential to show anti-cancer activity along with the promise to prolong survival in patients with SCLC. Treatment with the CTLA-4-specific antibodies can restore the immune response by increasing the accumulation and survival of T-cells whereas monoclonal antibodies block either PD-1 or its ligands that prevent downregulation of effector T-cell, which enables the T-cells to mediate the death of tumor cells. Furthermore, monoclonal antibody in combination with chemotherapy has attained quite a focus to enhance the survival of SCLC patients. Apart from this, various immunotherapeutic approaches have been evaluated in the clinical trials for SCLC patients such as TLR9 agonist, anti-CD47, anti-ganglioside therapy, and anti-Notch signaling. The current review focuses on the rationale as well as on the clinical studies of immunotherapy in SCLC along with the clinical end results of certain immunotherapeutic agents and novel therapeutic combinations in SCLC patients.

Poly(ADP-Ribose) Polymerase Inhibition in Small Cell Lung Cancer: A Review

ABSTRACT

Small cell lung cancer (SCLC) is a highly aggressive neuroendocrine malignancy with high and rapid relapse rates and poor outcomes. Treatment for SCLC has historically been limited by the lack of targetable driver genomic lesions, however recent developments in the underpinnings of genomic instability in SCLC and understanding of its transcriptional subtypes have led to increased interest in the use of poly(ADP-ribose) polymerase (PARP) inhibitors as a rationale therapy. Poly(ADP-ribose) polymerase inhibitors, historically designed to target BRCA1/2-mutated malignancies, capitalize on synthetic lethality in homologous recombination-deficient tumors. In this review, we outline the mechanistic rationale for the use of PARP inhibitors in treating SCLC and detail key clinical trials investigating their use in combination with chemotherapy and immunotherapy. We describe developments in the understanding of biomarkers for sensitivity to therapy and highlight further investigational directions for the use of PARP inhibitors in treating SCLC.

BRCA mutations in pancreatic cancer and progress in their targeting

Introduction: Genomic instability resulting from DNA damage repair (DDR) deficiencies is a hallmark of cancer and offers treatment opportunities. Homologous recombination DDR defect is a result of multiple critical gene mutations, including BRCA1/2. Targeting DNA DDR defects in pancreatic cancer (PC) is emerging as a potential treatment strategy with current focus on BRCA mutations.Areas covered: Challenges in treating patients with PC are explained. We review DDR defects as a treatment target in PC, specifically, germline BRCA mutation and sensitivity to platinum compounds and exploiting the strategy of synthetic lethality using poly (ADP-ribose) polymerase (PARP) inhibition. Literature review was undertaken through PubMed, Google Scholar, and Clinicaltrials.gov website.Expert opinion: DDR defects are promising targets for novel therapies in PC. Early application of such strategy is in patient subgroup with BRCA germline mutation, which is seen in only 5-7% of the PC population. The oral PARP inhibitor olaparib in the maintenance setting represents the first targeted therapy in metastatic PC based on a phase 3 study. There is a very modest benefit for patients with PC using PARP inhibitors. Future work must improve our understanding of mechanisms of sensitivity and resistance to PARP inhibitors in PC and enhance the molecular selection of patients for such therapy.

Repositioning PARP inhibitors in the treatment of thoracic malignancies

The evaluation of the homologous recombination repair (HRR) status is emerging as a predictive tumor agnostic biomarker for poly (ADP-ribose) polymerase (PARP) inhibition across different tumor types and testing for HRR-signature is currently a developing area with promising therapeutic implications. Treatment with PARP inhibitors (PARPi) either as single agent or in combination with chemotherapy have shown so far limited activity in patients with thoracic malignancies. A deeper understanding of the biological background underlying HRR-deficient tumors, along with the recent advent of new effective targeted and immunotherapeutic agents, prompted the design of a new generation of clinical trials investigating novel PARPi-combinations in patients with lung cancer as well as malignant pleural mesothelioma. In this review we briefly summarize the biological basis of the DNA damage response pathway inhibition and provide an updated and detailed overview of clinical trials testing different PARPi-combinations strategies in patients with thoracic malignancies.

Notch signaling and efficacy of PD-1/PD-L1 blockade in relapsed small cell lung cancer

Immune checkpoint blockade (ICB) benefits only a small subset of patients with small cell lung cancer (SCLC), yet the mechanisms driving benefit are poorly understood. To identify predictors of clinical benefit to ICB, we performed immunogenomic profiling of tumor samples from patients with relapsed SCLC. Tumors of patients who derive clinical benefit from ICB exhibit cytotoxic T-cell infiltration, high expression of antigen processing and presentation machinery (APM) genes, and low neuroendocrine (NE) differentiation. However, elevated Notch signaling, which positively correlates with low NE differentiation, most significantly predicts clinical benefit to ICB. Activation of Notch signaling in a NE human SCLC cell line induces a low NE phenotype, marked by increased expression of APM genes, demonstrating a mechanistic link between Notch activation, low NE differentiation and increased intrinsic tumor immunity. Our findings suggest Notch signaling as a determinant of response to ICB in SCLC.

Immune checkpoint blockade (ICB) benefits only a small subset of patients with small cell lung cancer (SCLC) and the mechanisms driving benefit are poorly understood. Here, the authors show that elevated Notch signaling predicts clinical benefit in ICB in relapsed SCLC.

The Synergistic Effect of PARP Inhibitors and Immune Checkpoint Inhibitors

Poly (ADP-ribose) polymerase (PARP) inhibitors have demonstrated great promise for treating cancers with homologous recombination (HR) defects, such as germline BRCA1/2 mutation. Further studies suggest that PARP inhibitors (PARPi) can also exhibit efficacy in HR-competent cancers, by amplifying the DNA damage and inducing immunogenic cell death, and PARPi lead to increasing tumor neoantigen, upregulation of interferons and PD-L1, and modulation of the tumor microenvironment, which may facilitate a more profound antitumor immune response. Immune checkpoint inhibitors (ICIs) targeting PD-1/PD-L1 or CTLA-4 have achieved impressive success in the treatment of different malignancies. However, only a subset of populations derive clinical benefit, and the biomarkers and resistance mechanisms are not fully understood. Therefore, given that PARPi could potentiate the therapeutic effect of ICIs, PARPi combined with ICIs are becoming an alternative for patients who cannot benefit from ICI monotherapy. In this review, we focus on the mechanisms and immune role of PARPi and discuss the rationale and clinical studies of this combined regimen.

PARP Inhibitors in Small-Cell Lung Cancer: Rational Combinations to Improve Responses

Simple Summary

Small-cell lung cancer carries a dismal prognosis with few long-term treatment options. The enzyme poly-(ADP)-ribose polymerase (PARP), which functions to repair DNA breaks, has emerged as a promising therapeutic target, with modest response rates in early clinical trials prompting investigation of predictive biomarkers and therapeutic combinations. This review summarizes the development and testing of PARP inhibitors in small-cell lung cancer with an emphasis on developing treatment combinations. These combinations can be divided into three categories: (1) contributing to DNA damage; (2) inhibiting the DNA damage response; and (3) activating the immune system. An evolving classification of small-cell lung cancer subtypes and gene expression patterns will guide PARP inhibitor biomarker identification to improve treatments for this challenging cancer.

Abstract

Despite recent advances in first-line treatment for small-cell lung cancer (SCLC), durable responses remain rare. The DNA repair enzyme poly-(ADP)-ribose polymerase (PARP) was identified as a therapeutic target in SCLC using unbiased preclinical screens and confirmed in human and mouse models. Early trials of PARP inhibitors, either alone or in combination with chemotherapy, showed promising but limited responses, suggesting that selecting patient subsets and treatment combinations will prove critical to further clinical development. Expression of SLFN11 and other components of the DNA damage response (DDR) pathway appears to select for improved responses. Combining PARP inhibitors with agents that damage DNA and inhibit DDR appears particularly effective in preclinical and early trial data, as well as strategies that enhance antitumor immunity downstream of DNA damage. A robust understanding of the mechanisms of DDR in SCLC, which exhibits intrinsic replication stress, will improve selection of agents and predictive biomarkers. The most effective combinations will target multiple nodes in the DNA damage/DDR/immune activation cascade to minimize toxicity from synthetic lethality.

Old but gold: the role of drug combinations in improving response to immune check-point inhibitors in thoracic malignancies beyond NSCLC

The introduction of immune checkpoint inhibitors (ICIs) in non-oncogene addicted non-small cell lung cancer (NSCLC) has revolutionized the treatment scenario and led to a meaningful improvement in patient prognosis. Disappointingly, the success of ICI therapy in NSCLC has not been fully replicated in other thoracic malignancies as small cell lung cancer (SCLC), malignant pleural mesothelioma (MPM), and thymic epithelial tumors (TETs), due to the peculiar biological features of these disease and to the difficulties in the conduction of well-designed, biomarker-driven clinical trials. Therefore, combination strategies of ICIs plus conventional therapies (either chemotherapy, alternative ICIs or targeted agents) have been implemented. Although first approvals of ICI therapy have been recently granted in SCLC and MPM (in combination with chemotherapy and different ICIs), results remain somewhat modest and limited to a small proportion of patients. This work reviews the trial results of ICI therapy in mesothelioma, SCLC, and TETs and discusses the potential of combining ICIs with old drugs.

Emerging drugs for small cell lung cancer: a focused review on immune checkpoint inhibitors

INTRODUCTION

Small cell lung cancer (SCLC) is an aggressive malignancy that accounts for 15% of all lung cancers. It is characterized by initial responsiveness to therapy followed by rapid disease progression that is relatively resistant to further treatment. Recently, the addition of an immune checkpoint inhibitor (ICI) to chemotherapy has improved survival in patients with advanced disease, the first advance in systemic therapy in SCLC in over 30 years.

AREAS COVERED

In this review, we present an overview of SCLC with a focus on the scope of the problem and standard treatment, followed by a critical assessment of scientific rationale for immunotherapy in SCLC and the clinical trials that have been performed with ICIs in SCLC. Finally, we address ongoing hurdles for the development of ICIs in SCLC and potential avenues for further study.

EXPERT OPINION

Despite solid biological rationale, the results of clinical trials of ICIs in SCLC have yielded modest benefits. A small subset of patients does achieve long-term benefit, but further development of ICIs in SCLC will depend on the identification of predictive biomarkers and the design of combination regimens that take advantage of the molecular alterations that drive the immune-avoidance mechanisms and survival of SCLC cells.

Landscape and Future Perspectives of Immunotherapy in Neuroendocrine Neoplasia

BACKGROUND

Neuroendocrine neoplasms are rare entities consisting of a heterogeneous group of tumors that can originate from neuroendocrine cells present in the whole body. Their different behavior, metastatic potential, and prognosis are highly variable, depending on site of origin, grade of differentiation, and proliferative index. The aim of our work is to summarize the current knowledge of immunotherapy in different neuroendocrine neoplasms and its implication in clinical practice.

RESULTS

Several studies evaluated the efficacy and safety of immunotherapy in neuroendocrine neoplasms, in any setting of treatment, alone or in combination. Studies led to approval in neuroendocrine neoplasia of the lung, in combination with chemotherapy as first-line treatment or as a single-agent in a third-line setting, and Merkel cell carcinoma as a single agent. Results in other settings have been disappointing so far.

CONCLUSIONS

Immunotherapy seems a valid treatment option for high grade, poorly differentiated neoplasms. Future trials should explore the combination of immunotherapy with other agents, such as anti-angiogenic or other immunotherapy agents, in order to evaluate potential efficacy in low and intermediate grades, well differentiated tumors.

Targeting DNA Repair to Drive Immune Responses: It's Time to Reconsider the Strategy for Clinical Translation

PARP inhibition induces robust local and systemic antitumor immune responses and curative responses when combined with immune checkpoint blockade in many preclinical studies. However, the combination has not markedly improved antitumor effect compared with individual agents in clinical trials to date. We propose that the data from these trials indicate a lack of synergistic interaction of PARP inhibition and immune checkpoint blockade, with implications for reexamining our current strategies for clinical translation. As current mouse models do not recapitulate the genomic heterogeneity or tumor microenvironment of human cancers, better models are urgently needed. Tumor-extrinsic factors modulate immune checkpoint blockade response and they may be better assessed in early-phase clinical trials with frequent tissue and blood sampling. Further work is also needed to uncover the dose and schedule dependency of DNA repair modulation on the immune system. In homologous recombination repair-deficient tumors, randomized trials should be prioritized to address whether the benefit is superior to that of PARP inhibitor monotherapy. In tumors that are not homologous recombination repair deficient, research biopsies should be integrated to early-phase clinical trials to discover biomarkers that can predict clinical benefit. These considerations are relevant to the variety of adjunctive therapeutics being combined with immune checkpoint blockade to improve probability, duration, and potency of antitumor activity.

PARP Inhibitors: Extending Benefit Beyond BRCA-Mutant Cancers

A mounting body of evidence now indicates that PARP inhibitors have the potential to be used as a foundation for both monotherapy and combination strategies across a wide spectrum of molecular backgrounds and tumor types. Although PARP inhibitors as a class display many similarities, critical differences in structure can translate into differences in tolerability and antitumor activity that have important implications for the clinic. Furthermore, while PARP inhibitors have demonstrated a clear role in treating tumors with underlying homologous recombination deficiencies, there is now biological and early clinical evidence to support their use in other molecular subsets of cancer, including tumors associated with high levels of replication stress such as small-cell lung cancer. In this article, we highlight the key similarities and differences between individual PARP inhibitors and their implications for the clinic. We discuss data that currently support clinical strategies for extending the benefit of PARP inhibitors beyond BRCA-mutant cancers, toward broader populations of patients through the use of novel biomarkers of homologous recombination repair deficiency (HRD), as well as predictive biomarkers rooted in mechanisms of sensitivity outside of HRD. We also explore the potential application of PARP inhibitors in earlier treatment settings, including neoadjuvant, adjuvant, and even chemoprevention approaches. Finally, we focus on promising combination therapeutic strategies, such as those with other DNA damage response (DDR) inhibitors such as ATR inhibitors, immune checkpoint inhibitors, and non-DDR-targeted agents that induce "chemical BRCAness."

Durvalumab in Combination with Olaparib in Patients with Relapsed SCLC: Results from a Phase II Study

PURPOSE

Despite high tumor mutationburden, immune checkpoint blockade has limited efficacy in SCLC. We hypothesized that poly (ADP-ribose) polymerase inhibition could render SCLC more susceptible to immune checkpoint blockade.

METHODS

A single-arm, phase II trial (NCT02484404) enrolled patients with relapsed SCLC who received durvalumab, 1500 mg every 4 weeks, and olaparib, 300 mg twice a day. The primary outcome was objective response rate. Correlative studies included mandatory collection of pretreatment and during-treatment biopsy specimens, which were assessed to define SCLC immunephenotypes: desert (CD8-positive T-cell prevalence low), excluded (CD8-positive T cells in stroma immediately adjacent/within tumor), and inflamed (CD8-positive T cells in direct contact with tumor).

RESULTS

A total of 20 patients were enrolled. Their median age was 64 years, and most patients (60%) had platinum-resistant/refractory disease. Of 19 evaluable patients, two were observed to have partial or complete responses (10.5%), including a patient with EGFR-transformed SCLC. Clinical benefit was observed in four patients (21.1% [95% confidence interval: 6.1%-45.6%]) with confirmed responses or prolonged stable disease (≥8 months). The most common treatment-related adverse events were anemia (80%), lymphopenia (60%), and leukopenia (50%). Nine of 14 tumors (64%) exhibited an excluded phenotype; 21% and 14% of tumors exhibited the inflamed and desert phenotypes, respectively. Tumor responses were observed in all instances in which pretreatment tumors showed an inflamed phenotype. Of the five tumors without an inflamed phenotype at baseline, no during-treatment increase in T-cell infiltration or programmed death ligand 1 expression on tumor-infiltrating immune cells was observed.

CONCLUSIONS

The study combination did not meet the preset bar for efficacy. Pretreatment and during-treatment biopsy specimens suggested that tumor immune phenotypes may be relevant for SCLC responses to immune checkpoint blockade combinations. The predictive value of preexisting CD8-positive T-cell infiltrates observed in this study needs to be confirmed in larger cohorts.