Denosumab combined with immunotherapy, radiotherapy, and granulocyte-macrophage colony-stimulating factor for the treatment of metastatic nasopharyngeal carcinoma: A case report

Abstract

BACKGROUND

Bone is a major site of metastasis in nasopharyngeal carcinoma (NPC). Recently, nuclear factor kappa-beta ligand (RANKL) inhibitors have garnered attention for their ability to inhibit osteoclast formation and bone resorption, as well as their potential to modulate immune functions and thereby enhance the efficacy of programmed cell death protein 1 (PD-1) inhibitor therapy.

CASE SUMMARY

We present a case of a patient with NPC who developed sternal stalk metastasis and multiple bone metastases with soft tissue invasion following radical chemoradiotherapy and targeted therapy. Prior to chemotherapy, the patient experienced severe bone marrow suppression and opted out of further chemotherapy sessions. However, the patient received combination therapy, including RANKL inhibitors (denosumab) alongside PD-1, radiotherapy, and granulocyte-macrophage colony-stimulating factor (PRaG) therapy (NCT05435768), and achieved 16 months of progression-free survival and more than 35 months of overall survival, without encountering any grade 2 or higher treatment-related adverse events.

CONCLUSION

Denosumab combined with PRaG therapy could be a new therapeutic approach for the second-line treatment in patients with bone metastases.

Key Words: Nasopharyngeal carcinoma; Bone metastasis; Radiotherapy; Programmed cell death protein 1 inhibitors; Denosumab; Case report

Core Tip: Bone is a common metastatic site in nasopharyngeal carcinoma (NPC). We report a patient with NPC who developed multiple bone metastases and soft tissue invasion after 1 year of curative chemoradiotherapy and targeted therapy. Due to severe bone marrow suppression from prior chemotherapy, the patient declined further treatment and received denosumab (receptor activating factor ligand inhibitor) combined with PRaG therapy. This regimen resulted in progression-free survival of 16 months and overall survival of more than 35 months, without any grade 2 or higher treatment-related adverse reactions, suggesting a novel therapeutic strategy for patients with refractory NPC.

INTRODUCTION

Despite simultaneous chemoradiotherapy, approximately 30% of patients with locally advanced cancer experience distant or recurring metastasis[1]. Bone is one of the most common metastatic sites of nasopharyngeal carcinoma (NPC), accounting for more than 50% of all metastatic occurrences[2].

Systemic treatments for metastatic NPC primarily include platinum-based chemotherapy, such as cisplatin. Recent studies have reported a 5-year survival rate of 19.2% with the first-line gemcitabine and cisplatin (GP) regimen[3]. The advent of immunotherapy in combination with platinum-based chemotherapy has significantly improved the survival outcomes of patients with metastatic NPC, increasing the median progression-free survival (PFS) from 6.9 months to 10.8 months[4]. This approach has become the standard treatment for metastatic NPC[5]. However, current treatment options remain limited for metastatic NPC due to failure in the first-line treatment or refractory to chemotherapy.

In this case report, we aimed to present a patient with NPC who developed multiple bone metastases following standard chemoradiotherapy and targeted therapy, which led to therapy-induced severe bone marrow suppression, resulting in patient noncompliance. Consequently, the patient opted for an innovative regimen combining receptor of nuclear factor kappa-beta ligand (RANKL) inhibitors with PRaG therapy.

CASE PRESENTATION

Chief complaints

A 63-year-old male Chinese patient was diagnosed with advanced NPC with multiple bone metastases 1 year after completing curative chemoradiotherapy.

History of present illness

The patient was diagnosed with stage IVA NPC with poorly differentiated squamous cell carcinoma in January 2021. He underwent three cycles of induction chemotherapy with docetaxel plus cisplatin (TP) regimen, consisting of paclitaxel (240 mg on day 1) + cisplatin (45 mg for 3 consecutive days from day 1 to day 3), in combination with nimotuzumab (400 mg on day 1) as targeted therapy. Radiation therapy was administered from April 1, 2021, to May 17, 2021. The radiation therapy consists of primary tumor lesion and metastatic retropharyngeal lymph node (PGTVnx) 71.28 Gy/2.16 Gy/33 Fx; PGTVnd (metastatic lymph nodes in bilateral II region) 66 Gy/2.0 Gy/33 Fx; planning target volume (PTV) 1 (includes high-risk areas around the primary focus, pterygoid sinus, skull base, sieve sinus, right soft palate, slope, pterygopalatine fossa, parotid gland, parapharyngeal space, and oropharynx) 66 Gy/2 Gy/33 Fx; PTV2 (right Ib, bilateral II, III, and Va regions) 61.05 Gy/1.85 Gy/33 Fx; PTV3 (bilateral IVa and Vb regions) 50.4 Gy/1.8 Gy/28 Fx.

Three cycles of TP regimen chemotherapy were administered from June to August 2021, with cycle one consisting of paclitaxel (240 mg on day 1) and cisplatin (45 mg from day 1 to day 3). Due to the development of severe bone marrow suppression (leukopenia), the dose was reduced by 75% (i.e., paclitaxel 180 mg on day one and cisplatin 30 mg from day 1 to day 3) in the subsequent second and third cycles.

After chemoradiotherapy, the follow-up magnetic resonance imaging indicated size reduction in the nasopharyngeal primary and cervical lymph nodes, with the tumor lesion remaining stable in several subsequent reviews. The partial response and progressive disease were evaluated per the RECIST 1.1 criteria. In August 2022, a follow-up examination revealed metastasis in the sternal stem and right iliac bone surrounded with soft tissue shadows.

History of past illness

The patient had no history of chronic diseases, including hypertension, diabetes, heart disease, or infectious diseases such as hepatitis B and tuberculosis.

Personal and family history

There was no personal or familial history of relevant tumor diseases.

Physical examination

The patient had pressure pain in the sternal and right iliac areas.

Laboratory examinations

The Epstein–Barr-DNA copy count was 6.62 × 10⁴ IU/mL (Figure 1A).

Figure 1 Examinations. A: The Epstein–Barr virus DNA changes during PRaG treatment; B: Computed tomography (CT) evaluation of sternal metastases at baseline and during treatment; C: CT evaluation of right iliac metastases at baseline and during treatment; D: Bone scans of the patient at baseline and during treatment; E Initial pathology and immunohistochemistry of the patient hematoxylin and eosin stain, mutS homolog (MSH) 2, MSH6, PMS1 homolog 2, and mutL homolog 1; F: The interleukin-6 changes during PRaG treatment. EB: Epstein–Barr; IL: Interleukin; HE: Hematoxylin and eosin; MSH2: MutS homolog 2; MSH6: MutS homolog 6; PMS2: PMS1 homolog 2; MLH1: MutL homolog 1.

Imaging examinations

Computed tomography scans indicated bone destruction of the sternal handle and right ilium with surrounding soft tissue shadow, which was considered to be metastatic bone lesions (Figure 1B and C). Emission computed tomography showed multiple metastatic bone lesions (Figure 1D).

FINAL DIAGNOSIS

Based on the patient’s medical history and relevant examinations, the ultimate diagnosis was multiple bone metastatic NPC.

TREATMENT

After being diagnosed with multiple bone metastases and declining chemotherapy, the patient was enrolled in a clinical trial (NCT05435768) and began treatment with RANKL inhibitors combined with PRaG therapy on September 1, 2022. The treatment protocol included a subcutaneous injection of denosumab (XGEVA; 120 mg, day 1), followed by stereotactic body radiotherapy (8 Gy × 3 fractions) from day 2 to day 4 (Figure 2A). Granulocyte-macrophage colony-stimulating factor (GM-CSF) was administered subcutaneously for 7 consecutive days during radiotherapy (200 μg, days 2-8), followed by sequential subcutaneous injections of human recombinant interleukin (IL)-2 for 7 consecutive days (2 million IU, days 9-15). A subcutaneous injection of programmed death receptor-ligand 1 (PD-L1) inhibitor (Envolizumab 400 mg, day 5) was given within a week of completing radiotherapy (the treatment regimen is shown in Figure 2B). The same treatment regimen was repeated every 3 weeks.

Figure 2 Treatment. A: The target area of the patient was irradiated by three radiation treatments during the PRaG 2.0X treatment; B: PRaG 2.0X treatment process. The patient received three cycles of RANKL inhibitor combined with radiotherapy and immunotherapy and 15 cycles of RANKL inhibitor combined with immunotherapy for consolidation therapy, including multiple imaging evaluations; C: The entire diagnosis and treatment process of the patient since being diagnosed with nasopharyngeal carcinoma. PD-1: Programmed cell death protein 1; PD-L1: Programmed death receptor-ligand 1; IL: Interleukin; GM-CSF: Granulocyte-macrophage colony-stimulating factor.

In early November 2022, after three cycles of treatment, the patient began consolidation therapy. Each cycle of consolidation therapy consisted of a subcutaneous injection of denosumab (XGEVA) (120 mg, day 1), followed by GM-CSF (200 µg, days 2-8) for 7 consecutive days, and sequential IL-2 injections (2 million IU, days 9-15) for 7 consecutive days. A PD-L1 inhibitor (Envolizumab 400 mg) was administered subcutaneously every 21 days (the patient’s course of treatment is shown in Figure 2C).

OUTCOME AND FOLLOW-UP

During the combination therapy (RANKL inhibitors combined with PRaG therapy), follow-up examinations revealed a significant reduction in size in both sternal and right iliac metastases, and a significant decrease in Epstein–Barr virus (EBV) copy number. In December 2023, the PFS of the patient was 16 months, and the overall survival (OS) exceeded 35 months, with no grade 2 or higher treatment-related adverse reactions. The patient is currently undergoing treatment with Envolizumab immunotherapy as monotherapy.

DISCUSSION

According to the phase 3 clinical trial, GP is the preferred first-line chemotherapy regimen for recurrent or metastatic NPC[3]. With the advent of immunotherapy, the CAPTAIN-1 clinical trial introduced camrelizumab into the GP regimen, which markedly increased the median PFS of patients with local recurrence and metastatic NPC to 10.8 months, compared with 6.9 months for the GP regimen alone. This combination also resulted in a 66% incidence of grade 3 or higher bone marrow suppression compared with 69% with the GP regimen alone[4].

The “PRaG therapy” designed by our research group and registered under ChiCTR1900026175, combines programmed cell death protein 1 (PD-1)/PD-L1 inhibitors, radiotherapy, and GM-CSF to treat patients with advanced posterior line tumor. The PRaG therapy targets three stages of the tumor-immunity cycle: (1) Radiotherapy to expose tumor antigens; (2) GM-CSF to activate antigen-presenting cells; and (3) PD-1/PD-L1 inhibitors to enhance the tumor-killing ability of specific CD8⁺T lymphocytes, thereby fostering a synergistic and effective tumor immune response[6]. The therapy aims to establish immune memory and addresses the tumor heterogeneity through multiple radiation therapy cycles, targeting different tumor parts. RANKL is a cytokine involved in osteoclast differentiation and plays a key role in pathologic bone resorption in patients with bone metastasis[7]. RANKL inhibitors are known for treating bone metastases or multiple myelomas, exhibiting antitumor immune effects when combined with immune checkpoint inhibitors (ICIs)[8]. A preclinical study demonstrated the potential of RANKL inhibitors in enhancing the antimetastatic efficacy of anti–PD-1/PD-L1 monoclonal antibodies[9]. Retrospective analyses have indicated that, compared with ICIs therapy alone, the combination of ICIs and RANKL inhibitors significantly improved the survival of patients with metastatic melanoma[10].

Based on our study results, combining RANKL inhibitors with PRaG therapy may further improve anticancer efficacy in patients with bone metastases. In this case, the patient was already in an advanced stage at the initial diagnosis. Given the high malignancy and the critical condition of the patient, induction of chemotherapy and targeted therapy were administered, which resulted in severe bone marrow suppression during adjuvant chemotherapy. Furthermore, after developing multiple bone metastases and considering the significant toxic side effects, the patient was noncompliant with undergoing chemotherapy, and opted for experimental treatment with RANKL inhibitors combined with PRaG therapy. After treatment, a significant reduction in bone metastases and copy numbers of EBV were observed.

In addition, the concentration of IL-6 significantly decreased during the treatment (Figure 1F). IL-6 is secreted by various cells, including dendritic cells, macrophages, B lymphocytes, T lymphocytes, and tumor cells[11]. It activates the IL-6/signal transduction and transcription activation factor 3-signaling pathway in cancer cells, supporting tumorigenesis by inhibiting apoptosis and promoting survival[12]. Notably, IL-6 was upregulated in different types of cancer. High IL-6 levels in the tumors were also associated with poor prognosis[13].

Flow cytometric analysis of immune function activation during the PRaG treatment in this patient revealed a slight increase in several immune cell populations, including HLA-DR⁺ CD38⁺CD8⁺Temra cells, CD4⁺CD39⁺T cells, CD4⁺CD39⁺PD-1⁺T cells, CD8⁺CD39⁺T cells, CD4⁺CD39⁺CD226⁺T cells, and CD8⁺CD39 ⁺CD226⁺T cells of the patient (Figure 3). CD226 is an adhesion molecule that stimulates natural killer cells and CD8⁺T cell-mediated cytotoxicity[14]. Recent research suggests that the absence of CD226 in CD8⁺T cells indicates a correlation with tumor progression, whereas an increase in CD226⁺CD8⁺T cells may correlate with better antitumor efficacy[15]. Moreover, CD39, an enzyme that works in concert with CD73, initiates the conversion of adenosine triphosphate to adenosine diphosphate and cyclic adenosine monophosphate, ultimately releasing adenosine, which has immunosuppressive effects in the tumor microenvironment[16]. Although tumors can exploit CD39 upregulation as a mechanism to evade immune responses, CD39 expression on CD8⁺T cells has been shown to predict the efficacy of anti–PD–1 immunotherapy in some patients with advanced cancers[17]. These immune changes may preliminarily indicate that PRaG therapy exerts a stimulating effect on the patient’s immune system, thereby enhancing the immune-mediated antitumor effect.

Figure 3 Percentage of peripheral blood lymphocytes during PRaG treatment. The percentage of CD4⁺T cells and CD8⁺T cell subsets increased to varying degrees during PRaG treatment.

The patient’s PFS reached 16 months, and OS exceeded 35 months, and was continuing with the single-agent immune maintenance therapy, with a survival period higher than the median OS of first-line GP combined with immunotherapy (PFS, 95%CI: 8.5-13.6 months). Importantly, no grade 2 or higher adverse reactions were observed during the treatment. The results of the short-term efficacy evaluation of this case were significantly better than those previously reported in the literature, providing a new reference for the treatment options for patients with NPC and bone metastases and who have failed the first-line treatment or are unable to tolerate chemotherapy.

CONCLUSION

After treatment with RANKL inhibitors coupled with the PRaG therapy regimen, the patient achieved prolonged survival with a PFS of 16 months and an OS exceeding 35 months, along with a high safety profile characterized by only grade 1 treatment-related adverse events. Bone is the predominant site of metastasis in advanced NPCs. The treatment regimen used in this case provides valuable insights for patients with bone metastases who either fail in first-line treatment or have difficulty tolerating chemotherapy. To the best of our knowledge, this is the first prospective report on the safety and efficacy of RANKL inhibitors combined with PD-1 inhibitors. The efficacy and safety of this treatment paradigm need to be further analyzed and validated in open-label prospective studies.

ACKNOWLEDGEMENTS

We are grateful to the patient and her family.