MA16.06 Durvalumab ± Tremelimumab + Platinum-Etoposide in 1L ES-SCLC: Exploratory Analysis of HLA Genotype and Survival in CASPIAN

Durvalumab ± Tremelimumab + Platinum-Etoposide in Extensive-Stage Small Cell Lung Cancer (CASPIAN): Outcomes by PD-L1 Expression and Tissue Tumor Mutational Burden

PURPOSE

In the CASPIAN trial, first-line durvalumab plus platinum-etoposide (EP) significantly improved overall survival (OS) versus EP alone in extensive-stage small cell lung cancer (ES-SCLC). We report exploratory analyses of CASPIAN outcomes by programmed cell death ligand-1 (PD-L1) expression and tissue tumor mutational burden (tTMB).

EXPERIMENTAL DESIGN

Patients were randomized (1:1:1) to durvalumab (1,500 mg) plus EP, durvalumab plus tremelimumab (75 mg) plus EP, or EP alone. Treatment effects in PD-L1 and tTMB subgroups were estimated using an unstratified Cox proportional hazards model.

RESULTS

The PD-L1 and tTMB biomarker-evaluable populations (BEP) comprised 54.4% (438/805) and 35.2% (283/805) of the intention-to-treat population, respectively. PD-L1 prevalence was low: 5.7%, 25.8%, and 28.3% had PD-L1 expression on ≥1% tumor cells (TC), ≥1% immune cells (IC), and ≥1% TCs or ICs, respectively. OS benefit with durvalumab plus EP versus EP was similar across PD-L1 subgroups, with HRs all falling within the 95% confidence interval (CI) for the PD-L1 BEP (0.47‒0.79). OS benefit with durvalumab plus tremelimumab plus EP versus EP was greater in PD-L1 ≥1% versus <1% subgroups, although CIs overlapped. There was no evidence of an interaction between tTMB and treatment effect on OS (durvalumab plus EP vs. EP, P = 0.916; durvalumab plus tremelimumab plus EP vs. EP, P = 0.672).

CONCLUSIONS

OS benefit with first-line durvalumab plus EP in patients with ES-SCLC was observed regardless of PD-L1 or tTMB status. PD-L1 expression may prove to be a useful biomarker for combined treatment with PD-(L)1 and CTLA-4 inhibition, although this requires confirmation with an independent dataset. See related commentary by Rolfo and Russo, p. 652.

Tissue and circulating biomarkers of benefit to immunotherapy in extensive-stage small cell lung cancer patients

Extensive stage-Small-Cell Lung Cancer (ES-SCLC) is an aggressive cancer with dismal prognosis. The addition of immune-checkpoint inhibitors (ICIs) to platinum-based chemotherapy have been consistently demonstrated to improve outcomes and survival, becoming the new standard in first - line treatment of ES-SCLC patients. However, despite positive results reported in the pivotal trials, longer benefit appears evident only for a selected group of patients. Several predictive biomarkers have been studied so far but the prospective identification of patients more likely to experience better outcome seems to be challenging in SCLC. Indeed, classical immune predictive biomarkers as PD-L1 and tumor mutational burden (TMB) seem not to correlate with outcomes. Recently, a new molecular classification of SCLC based on differential expression of genes associated with specific clinical behaviors and therapeutic vulnerability have been presented suggesting a new field to be investigated. Despite the achievements, these studies focused mainly on inter-tumoral heterogeneity, limiting the exploration of intra-tumoral heterogeneity and cell to cell interactions. New analysis methods are ongoing in order to explore subtypes plasticity. Analysis on single biopsies cannot catch the whole genomic profile and dynamic change of disease over time and during treatment. Moreover, the availability of tissue for translational research is limited due to the low proportion of patients undergoing surgery. In this context, liquid biopsy is a promising tool to detect reliable predictive biomarkers. Here, we reviewed the current available data on predictive role of tissue and liquid biomarkers in ES-SCLC patients receiving ICIs. We assessed latest results in terms of predictive and prognostic value of gene expression profiling in SCLC. Finally, we explored the role of liquid biopsy as a tool to monitor SCLC patients over time.

Predictive biomarkers for immunotherapy response in extensive-stage SCLC

BACKGROUND

Small cell lung cancer (SCLC) accounts for about 13-15% of all lung cancers, and about 70% of SCLC patients have developed extensive-stage small cell lung cancer (ES-SCLC) at the time of diagnosis because of its highgrade malignancy, easy invasion, and metastasis. In recent years, immunotherapy combined with chemotherapy has become the standard first-line treatment for ES-SCLC. However, SCLC is a relatively immune-cold lung cancer subtype with a limited number of beneficiaries and a short benefit period. Therefore, the use of biomarkers to identify populations with significant benefits from immunotherapy will help improve the efficacy and survival benefits of immunotherapy. However, predictive biomarkers suitable for clinical practice have not been established in the field of SCLC.

PURPOSE

In order to find the predictive biomarkers of immunotherapy for ES-SCLC, we summarized the research progress of traditional biomarkers, such as programmed cell death ligand 1 (PD-L1) and tumor mutation burden (TMB), and summarizes the research of potential biomarkers associated with prognosis, such as molecular subtypes, special gene expression, expression of major histocompatibility complex (MHC) I and II classes, tumor immune microenvironment (TIME), and circulating tumor DNA (ctDNA) .We aim to provide new insights on biomarkers.

CONCLUSION

The exploration of biomarkers for immunotherapy of SCLC is still very difficult, and it is clear that conventional predictive biomarkers are not suitable for SCLC. At present, the molecular subtypes defined from transcription factors may have some guiding significance, which still needs to be confirmed by prospective clinical studies. In addition, the ctDNA positivity rate of SCLC is higher than that of other tumor types, which can also solve the dilemma of the difficulty of obtaining specimens of SCLC tissues. And the dynamic change of ctDNA also has great potential to predict the curative effect of SCLC, which is worth further clinical exploration.

The Era of Immunotherapy in Small-Cell Lung Cancer: More Shadows Than Light?

Small-cell lung cancer is an extremely chemo-sensitive disease; the addition of immunotherapy to chemotherapy has demonstrated a slight clinical benefit in pivotal trials, even with a statistically significant difference in terms of survival outcomes when compared to chemotherapy alone. In this scenario, the role of radiotherapy as a consolidation treatment in thoracic disease or as a prophylactic therapy in the brain should be clarified. In addition, due to the frailty and the poor prognostic characteristics of these patients, the need for predictive biomarkers that could support the use of immunotherapy is crucial. PD-L1 and TMB are not actually considered definitive biomarkers due to the heterogeneity of results in the literature. A new molecular classification of small-cell lung cancer based on the expression of key transcription factors seems to clarify the disease behavior, but the knowledge of this molecular subtype is still insufficient and the application in clinical practice far from reality; this classification could lead to a better understanding of SCLC disease and could provide the right direction for more personalized treatment. The aim of this review is to investigate the current knowledge in this field, evaluating whether there are predictive biomarkers and clinical patient characteristics that could help us to identify those patients who are more likely to respond to immunotherapy.

Shaping the tumor immune microenvironment of SCLC: Mechanisms, and opportunities for immunotherapy

Small-cell lung cancer (SCLC) is a very aggressive neuroendocrine tumor with a poor prognosis. Whereas immunotherapy has emerged as a promising approach for treating SCLC, its unique tumor immune microenvironment (TIME) might limit patient responses. To fully characterize the TIME and understand the mechanism of its formation with respect to SCLC is crucial. The recent rapid development of multi-omics technologies has rapidly advanced knowledge of TIME features and the regulatory mechanisms associated with SCLC. This review summarizes the TIME features of SCLC as well as shaping the TIME according to the genomics, epigenomics, and metabolomics of tumors. Future opportunities and challenges for immunotherapy are also discussed.

Harnessing DLL3 inhibition: From old promises to new therapeutic horizons

Small-cell lung cancer (SCLC) is an aggressive neuroendocrine tumor with a high relapse rate, limited therapeutic options, and poor prognosis. The combination of chemotherapy and immune-checkpoint inhibitors brings a new therapeutic era, although the lack of predictive biomarkers of response reduces the efficacy of applying the treatment to the entire population of patients with SCLC. The lack of treatments able to bind to a specific target has always been a substantial difference to the non-small cell lung cancer (NSCLC) counterpart. Delta-like canonical Notch ligand 3 is a protein frequently overexpressed in SCLC and is therefore being explored as a potentially promising therapeutic target in high-grade neuroendocrine lung cancer. In this article, we critically review the activity and efficacy of old DLL3 inhibitors antibody-drug conjugate (ADC) and their failures through new compounds and their possible applications in clinical practice, with a focus on new molecular classification of SCLC.

Durvalumab, with or without tremelimumab, plus platinum-etoposide in first-line treatment of extensive-stage small-cell lung cancer: 3-year overall survival update from CASPIAN

Background

In the phase III CASPIAN study, first-line durvalumab in combination with etoposide plus either cisplatin or carboplatin (EP) significantly improved overall survival (OS) versus EP alone in extensive-stage small-cell lung cancer (ES-SCLC). Durvalumab plus tremelimumab plus EP numerically improved OS versus EP, but did not reach statistical significance. Here we report updated OS in censored patients after median follow-up of >3 years.

Patients and methods

805 patients with treatment-naïve ES-SCLC were randomized 1 : 1 : 1 to durvalumab plus EP, durvalumab plus tremelimumab plus EP, or EP. The two primary endpoints were OS for durvalumab plus EP versus EP and for durvalumab plus tremelimumab plus EP versus EP.

Results

As of 22 March 2021 (median follow-up 39.4 months, 86% maturity), durvalumab plus EP continued to demonstrate improved OS versus EP: hazard ratio (HR) 0.71 [95% confidence interval (CI) 0.60-0.86; nominal P = 0.0003]; median OS was 12.9 versus 10.5 months, and 36-month OS rate was 17.6% versus 5.8%. Durvalumab plus tremelimumab plus EP continued to numerically improve OS versus EP: HR 0.81 (95% CI: 0.67-0.97; nominal P = 0.0200); median OS was 10.4 months, and 36-month OS rate was 15.3%. Twenty-seven and nineteen patients in the durvalumab plus EP and durvalumab plus tremelimumab plus EP arms, respectively, remained on durvalumab treatment at data cut-off.

Conclusions

Three times more patients were estimated to be alive at 3 years when treated with durvalumab plus EP versus EP, with the majority still receiving durvalumab at data cut-off, further establishing durvalumab plus EP as first-line standard of care for ES-SCLC.

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Durvalumab plus EP showed sustained OS benefit over EP with a well-tolerated safety profile after median follow-up >3 years.

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Three times more patients were estimated to be alive at 3 years when treated with durvalumab plus EP versus EP alone.

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These results further establish durvalumab plus EP as standard of care for first-line treatment of patients with ES-SCLC.