PDAC remains a highly aggressive and devastating disease, typically characterized by a median OS of less than 13 months in metastatic patients(Middleton et al. 2014). Posterior cardiac invasion is considered a manifestation of peritoneal metastasis, rendering surgical resection not recommended. Consequently, systemic chemotherapy is the established first-line approach for metastatic PDAC(Lellouche et al. 2021).
In this case, the application of NGS testing on the patient's blood and archived specimens revealed the presence of a BRCA2 mutation, along with negative PD-L1 expression, a low TMB, and MSS. The BRCA gene is responsible for encoding proteins involved in homologous recombination repair of double-stranded DNA breaks(Walsh 2015). Consequently, PDAC featuring a germline BRCA mutation exhibits sensitivity to platinum and PARP inhibitors(Andrei et al. 2015, Wang et al. 2020). The POLO study investigated the efficacy of maintenance olaparib in patients with platinum-sensitive metastatic PC who carried germline BRCA1 or BRCA2 mutations(Golan et al. 2019). The results showed that maintenance olaparib significantly extended PFS compared to placebo (median, 7.4 months vs. 3.8 months; P = 0.004)(Golan et al. 2019). However, there was no significant difference in median OS between the two groups (18.9 months vs. 18.1 months; P = 0.68)(Golan et al. 2019). Moreover, in this specific case, the patient and their family have adamantly declined chemotherapy. Hence, it is imperative to explore alternative chemotherapy-free treatment modalities, aiming to provide enhanced survival prospects for individuals with PDAC.
In recent years, significant attention has been dedicated to the research and development of anti-angiogenic drugs for managing PC. A phase III clinical trial demonstrated the superiority of combining erlotinib with gemcitabine compared to gemcitabine alone, as it led to notable improvements in both OS and PFS in patients with locally advanced or metastatic PC(Moore et al. 2007). However, it is noteworthy that various other anti-angiogenic drug combinations with gemcitabine have not yielded favorable outcomes concerning OS in PC patients(Van Cutsem et al. 2004, Van Cutsem et al. 2009, Kindler et al. 2010, Kindler et al. 2011, Gonçalves et al. 2012, Rougier et al. 2013, Yamaue et al. 2015, Sinn et al. 2017). These findings suggest that the utilization of anti-angiogenic drugs in conjunction with gemcitabine may have some inherent limitations in extending the OS of PC patients. Therefore, there is a pressing need to explore a new anti-angiogenic drug to improve the efficacy of PC treatment.
Anlotinib is a novel multi-targeted tyrosine kinase inhibitor renowned for its capacity to impede both tumor angiogenesis and cell proliferation(Sun et al. 2016). This therapeutic agent exhibits a broad spectrum of inhibitory effects on various critical targets, encompassing receptor tyrosine kinases such as vascular endothelial growth factor receptor 1 to 3, epidermal growth factor receptor (EGFR), fibroblast growth factor receptor 1 to 4, platelet-derived growth factor receptor α and β, stem cell factor receptor, and c-kit(Han et al. 2018). Clinical studies have shown that anlotinib has promising efficacy in the treatment of advanced NSCLC, small cell lung cancer, soft tissue sarcoma (STS), advanced thyroid carcinoma, and metastatic RCC(Wu et al. 2022, Shen et al. 2018). Moreover, its potential role in the context of PC has garnered substantial attention. Yang et al. found that anlotinib can induce the apoptosis of pancreatic cells both in vitro and in vivo by generating reactive oxygen species(Yang et al. 2020). Additionally, Zhang et al. shave demonstrated that anlotinib possesses the capacity to inhibit ribosomes within pancreatic cancer cells, thereby modulating various cellular functions, including the cell cycle, RNA metabolism, and lysosome(Zhang et al. 2021). In a retrospective study, the combination of anlotinib and nab-paclitaxel/gemcitabine showed a significant improvement in both PFS (5 months vs. 2.7 months, P=0.0220) and OS (9 months vs. 6 months, P=0.0060) in patients with unresectable or metastatic PDAC when compared to albumin-bound paclitaxel/gemcitabine(Wu et al. 2022). This treatment also maintained favorable tolerability profiles(Wu et al. 2022). Therefore, anlotinib is expected to be a feasible treatment modality for patients with locally advanced and metastatic PC.
Immunotherapy has revolutionized the treatment of various tumors(Timmer et al. 2021). Recent years have witnessed a notable surge in investigations into ICIs for the treatment of metastatic PC. Several studies have yielded compelling evidence suggesting that combining ICIs with chemotherapy holds promise for enhancing survival outcomes in patients with advanced PC(Zhang et al. 2022, Shui et al. 2020, Liu et al. 2022). However, it is worth noting that, except for high microsatellite instability (MSI-H) or DNA mismatch repair (dMMR), the outcomes of immunotherapy monotherapy or dual-agent immunotherapy in the context of advanced PC have often been underwhelming(Marabelle et al. 2020, Padrón et al. 2022, Feng et al. 2017, Royal et al. 2010, O'Reilly et al. 2019, Le et al. 2017). In our case, the patient was diagnosed with a BRCA2 mutation. Preclinical studies have illuminated that BRCA2 mutations could remodel the tumor microenvironment by fostering the enrichment of various immune cell populations, including T cells, natural killer cells, macrophages, and dendritic cells(Samstein et al. 2021). This, in turn, augments the anti-tumor activity of ICIs(Samstein et al. 2021). However, the patient in our case has several features that are unresponsive to ICIs, such as negative PD-L1 expression, low TMB, and MSS. Consequently, it is conceivable that immunotherapy alone may offer limited efficacy in this particular scenario.
Emerging research has shed light on the potential immunostimulatory effects of anti-angiogenic drugs and their capacity for synergistic anti-tumor action when combined with ICIs(Rini et al. 2019, Socinski et al. 2018, Motzer et al. 2019, Finn et al. 2020, Makker et al. 2019, Li et al. 2022). One notable example is the IMPOWER-150 study, which demonstrated that the addition of atezolizumab to bevacizumab, in combination with chemotherapy as a first-line treatment for metastatic NSCLC, led to improved clinical outcomes for patients, irrespective of their PD-L1 expression status or the presence of EGFR or ALK mutations(Socinski et al. 2018). In addition, Kang et al. reported a case in which the combination of pembrolizumab and anlotinib exhibited substantial anti-tumor activity in PC(Mafei et al. 2022). Similarly, Wang et al. documented a long-term partial response and favorable tolerability in a younger PDAC patient with KRAS G12V mutation and liver metastasis who received the combination of anlotinib with PD-1 inhibitor plus chemotherapy(Wang et al. 2022). Building upon these insights, we sought to explore the potential benefits of combining tislelizumab with anlotinib in the treatment of PC, specifically focusing on patients with metastatic BRCA2 mutated PDAC. Following the administration of four treatment cycles, the patient's response to therapy was evaluated as CR, and this remarkable efficacy persisted for a duration exceeding 13 months. Table 1 provides a summary of clinical studies conducted in the context of PC involving patients with BRCA2 or BRCA1/2 mutations.
In conclusion, we presented a novel and efficacious combination therapy involving immuno- and anti-angiogenic drugs for the treatment of patients with recurrent and metastatic PDAC and BRCA2 mutations. This innovative treatment approach holds promise for diversifying the therapeutic options available to patients with recurrent and metastatic PDAC and BRCA2 mutations, particularly for individuals who either decline or are unable to tolerate conventional chemotherapy. Nonetheless, it is imperative to emphasize that rigorous and extensive clinical trials are still indispensable to substantiate its efficacy and safety, thereby advancing its adoption in clinical practice.