The role of response adapted therapy in the era of novel agents.

The optimal treatment of classic Hodgkin Lymphoma (cHL) requires an individualized approach, with therapy guided by pretreatment clinical risk stratification and interim response assessment with positron emission tomography (PET). The overall goal is to achieve high cure rates while minimizing acute toxicity and late therapy-related effects. Interim PET-adapted strategies (iPET) were initially developed with traditional chemotherapy, reducing intensity after interim complete response and escalating treatment for patients with iPET+ disease. Recently, novel agents including brentuximab vedotin and the checkpoint inhibitor immunotherapies (CPIs) pembrolizumab and nivolumab have been adopted into the front-line treatment of cHL, and PET-adapted approaches may be relevant for these drugs as well. In this review we discuss response-adapted strategies utilizing novel agents, consider challenges including indeterminate radiographic findings with CPIs, and address emerging techniques for response assessment including new PET-based imaging metrics and the role of circulating tumor DNA.

Chemo-resistant Gestational Trophoblastic Neoplasia and the Use of Immunotherapy: A Case Report and Review of Literature.

This is the first reported case of the use of immunotherapy in chemo-resistant Gestational Trophoblastic Neoplasia (GTN) in the country. A 41-year-old, Gravida 4 Para 3 (3013) with a diagnosis of GTN, Stage III: WHO risk score of 13 (Choriocarcinoma) was initially managed with 10 cycles of multiple agent Etoposide, Methotrexate, Actinomycin D-Cyclophosphomide and Vincristine (EMACO) and 19 cycles of Etoposide, Cisplatin-Etoposide Methotrexate and Actinomycin D (EP-EMA). With continuous rise in beta human chorionic gonadotropin (ßhCG) levels, the patient was referred to a Trophoblastic Disease Center where there was note of tumor progression to the brain. She was started on third-line salvage chemotherapy of Paclitaxel and Carboplatin (PC) with concomitant whole brain irradiation completing three cycles after which chemoresistance was again diagnosed with increasing hCG titers and increase in the number and size of the pulmonary masses which were deemed unresectable. Immunotherapy was started with Pembrolizumab showing a good response with marked fall in ßhCG levels. The onset of immune-related adverse events (irAEs) caused a marked delay in subsequent cycles of immunotherapy. With management of the irAEs, two more cycles of Pembrolizumab with fifty percent dose reduction were given with corresponding drop in ßhCG levels. However, the patient subsequently developed gram-negative septicemia with possible hematologic malignancy and finally succumbed to massive pulmonary embolism. The case highlights the importance of prompt diagnosis and referral to a Trophoblastic Disease Center and the use of immunotherapy in chemo-resistant GTN.

Patterns of brain metastases response to immunotherapy with pembrolizumab.

PURPOSE: Central nervous system (CNS) metastases from lung cancers and melanoma, significantly contribute to morbidity and mortality. Despite advances in local therapies, there is a need for effective systemic treatments. Pembrolizumab, a PD-1 inhibitor, has shown promise for some patients with untreated brain metastases from melanoma and non-small cell lung cancer (NSCLC). This study aims to analyze the response of brain metastasis to pembrolizumab and associate characteristics like size and location with treatment outcome. METHODS: This retrospective study used imaging data from a phase II trial of pembrolizumab in melanoma or NSCLC patients with untreated brain metastases. MRI evaluations were conducted at 2 month intervals, with each brain metastasis treated as a distinct tumor for response assessment, based on modified RECIST criteria (maximum 5 lesions, 5 mm target lesions). RESULTS: Of 130 individual target metastases (> 5 mm), in 65 patients with NSCLC (90 metastases) and Melanoma (40 metastases), 32 (24.6%) demonstrated complete resolution, 24 (18.5%) had partial resolution, 32 (24.6%) were SD and 42 (32.3%) demonstrated PD. Those smaller than 10 mm were more likely to show complete resolution (p = 0.0218), while those ≥ 10 mm were more likely to have PR. There was no significant association between size, number or location (supratentorial vs. infratentorial) and lesion progression. The median time to metastatic lesion progression in the brain was 5.7-7 weeks. CONCLUSION: Pembrolizumab is effective in brain metastases from NSCLC and melanoma, showing response (CR + PR) in 43% and progression (PD) in 32% of metastases. With the median time to CNS progression of 5.7-7 weeks, careful radiographic monitoring is essential to guide timely local treatment decisions.

Small-Angle X-ray Scattering as a Powerful Tool for Phase and Crystallinity Assessment of Monoclonal Antibody Crystallites in Support of Batch Crystallization.

Crystalline suspensions of monoclonal antibodies (mAbs) have great potential to improve drug substance isolation and purification on a large scale and to be used for drug delivery via high-concentration formulations. Crystalline mAb suspensions are expected to have enhanced chemical and physical properties relative to mAb solutions delivered intravenously, making them attractive candidates for subcutaneous delivery. In contrast to small molecules, the development of protein crystalline suspensions is not a widely used approach in the pharmaceutical industry. This is mainly due to the challenges in finding crystalline hits and the suboptimal physical properties of the resulting crystallites when hits are found. Modern advances in instrumentation and increased knowledge of mAb crystallization have, however, resulted in higher probabilities of discovering crystal forms and improving their particle properties and characterization. In this regard, physical, analytical characterization plays a central role in the initial steps of understanding and later optimizing the crystallization of mAbs and requires careful selection of the appropriate tools. This contribution describes a novel crystal structure of the antibody pembrolizumab and demonstrates the usefulness of small-angle X-ray scattering (SAXS) for characterizing its crystalline suspensions. It illustrates the advantages of SAXS when used to (i) confirm crystallinity and crystal phase of crystallites produced in batch mode; (ii) confirm crystallinity under various conditions and detect variations in crystal phases, enabling fine-tuning of the crystallizations for phase control across multiple batches; (iii) monitor the physical response and stability of the crystallites in suspension with regard to filtration and washing; and (iv) monitor the physical stability of the crystallites upon drying. Overall, this work highlights how SAXS is an essential tool for mAb crystallization characterization.

Improved efficacy of pembrolizumab combined with soluble EphB4-albumin in HPV-negative EphrinB2 positive head neck squamous cell carcinoma.

OBJECTIVE: Patients with relapsed or metastatic head and neck squamous cell carcinoma (HNSCC) after primary local therapy have low response rates with cetuximab, systemic chemotherapy or check point inhibitor therapy. Novel combination therapies with the potential to improve outcomes for patients with HNSCC is an area of high unmet need. METHODS: This is a phase II single-arm clinical trial of locally advanced or metastatic HNSCC patients treated with a combination of soluble EphB4-human serum albumin (sEphB4-HSA) fusion protein and pembrolizumab after platinum-based chemotherapy with up to 2 prior lines of treatment. The primary endpoints were safety and tolerability and the primary efficacy endpoint was overall response rate (ORR). Secondary endpoints included progression free survival (PFS) and overall survival (OS). HPV status and EphrinB2 expression were evaluated for outcome. RESULTS: Twenty-five patients were enrolled. Median follow up was 40.4 months (range 9.8 - 40.4). There were 6 responders (ORR 24%). There were 5 responders in the 11 HPV-negative and EphrinB2 positive patients, (ORR 45%) with 2 of these patients achieving a complete response (CR). The median PFS in HPV-negative/EphrinB2 positive patients was 3.2 months (95% CI 1.1, 7.3). Median OS in HPV-negative/EphrinB2 positive patients was 10.9 months (95% CI 2.0, 13.7). Hypertension, transaminitis and fatigue were the most common toxicities. DISCUSSION: The combination of sEphB4-HSA and pembrolizumab has a favorable toxicity profile and favorable activity particularly among HPV-negative EphrinB2 positive patients with HNSCC.

Primary cervical malignant melanoma that was successfully treated with pembrolizumab: a case report and literature review.

Primary malignant melanoma (MM) arising from the cervix is an exceedingly rare occurrence, and patients diagnosed with this condition often face a dismal clinical prognosis. Here, we present a case study of a postmenopausal woman presenting with vaginal bleeding and a conspicuous 5-centimeter black mass on the cervix. Based on the staging criteria established by the International Federation of Gynecology and Obstetrics, she was diagnosed with stage IIB primary cervical MM. The patient underwent neoadjuvant therapy prior to a radical hysterectomy and a bilateral salpingo-oophorectomy. Subsequently, she completed 18 cycles of pembrolizumab therapy, achieving clinical complete remission. Notably, at the 31-month follow-up, there were no signs of recurrence. This successful treatment outcome serves as a valuable clinical reference for the management of primary cervical MM.

Pembrolizumab combined with chemotherapy versus placebo combined with chemotherapy for HER2-negative advanced gastric cancer in China: a cost-effectiveness analysis.

OBJECTIVE: This study aims to conduct a cost-effectiveness analysis of pembrolizumab in combination with chemotherapy for HER2-negative advanced gastric cancer in China. METHODS: A partitioned survival approach model was constructed to simulate the progression of HER2-negative advanced gastric cancer and evaluate the outcomes of different treatment strategies. We calculated incremental cost-effectiveness ratios (ICER) to assess the cost associated with each quality-adjusted life-year (QALY) gained. One-way sensitivity analysis and probabilistic sensitivity analysis were performed to assess robustness and reliability. RESULTS: The analysis conducted in the base case demonstrated that the ICER associated with pembrolizumab was $177405.83/QALY gained in all population. In the subgroup analysis, it was found that individuals with a PD-L1 CPS ≥ 1 and those with a PD-L1 CPS ≥ 10 had ICERs of $152397.06/QALY and $109534.13/QALY, respectively. All ICER values for both the all population groups and the subgroups exceeded the WTP threshold in China. Our analysis shows the robustness of these results, as they remained consistent when input parameters were varied within a ± 25% range. CONCLUSION: The findings of this cost-effectiveness analysis suggest that pembrolizumab in combination with chemotherapy is not a cost-effective treatment option for HER2-negative advanced gastric cancer in China.

Cost-effectiveness analysis of pembrolizumab plus chemotherapy versus placebo plus chemotherapy for HER2-negative advanced gastric/gastroesophageal junction cancer in the Chinese healthcare system.

BACKGROUND: This study compares first-line pembrolizumab plus chemotherapy with chemotherapy alone for patients with HER2-negative advanced gastric cancer (GC) and gastroesophageal junction cancer (GEJC) in China. METHODS: A Markov state-transition model was developed based on the phase 3 randomized KEYNOTE-859 clinical trial data. The health state utility values and direct medical costs were derived from the KEYNOTE-859 clinical trial, the relevant literature, and local charges. The measured outcomes included quality-adjusted life-years (QALYs) and the incremental cost-effectiveness ratio (ICER). Probabilistic and one-way sensitivity analyses (OWSA) were performed to assess the uncertainty of the model. RESULTS: In the base analysis, the incremental effectiveness and cost of pembrolizumab plus chemotherapy versus chemotherapy alone were 0.22 QALYs and $16,627.31, respectively, resulting in an ICER of $76,936.60/QALY, which is higher than the willingness-to-pay threshold in China ($35,864.61/QALY). Subgroup analyses revealed that the ICERs of pembrolizumab plus chemotherapy versus chemotherapy alone were $72,762.68 and $34,813.70 in the populations with PD-L1 CPS of 1 or higher (CPS ≥ 1) and PD-L1 CPS ≥ 10 (CPS ≥ 10), respectively. CONCLUSIONS: As first-line therapy for patients with locally advanced or metastatic HER2-negative GC/GEJC in China, pembrolizumab plus chemotherapy is less cost-effective than chemotherapy alone, however, in the CPS ≥ 10 subgroup is more.

Metastatic Urothelial Carcinoma With Sarcomatoid Subtype After Robot-Assisted Radical Cystectomy Successfully Treated With Pembrolizumab.

A 76-year-old man who was diagnosed with urothelial carcinoma (UC) in the bladder diverticulum was referred to our institution. The patient was diagnosed with muscle-invasive bladder cancer, which was confirmed by magnetic resonance imaging that showed tumor invasion into the fatty tissue surrounding the diverticulum. After two cycles of neoadjuvant gemcitabine and cisplatin, he underwent robot-assisted radical cystectomy (RARC) with pelvic lymph node dissection followed by intracorporeal ileal conduit. The histopathologic diagnosis of the bladder tumor was UC with squamous differentiation and sarcomatoid subtype and ypT3bN0M0 without positive surgical margins. The patient refused any adjuvant therapy. Six months after RARC, the patient visited our institution with a complaint of suddenly occurring generalized pain. Because 18F-fluorodeoxyglucose positron emission tomography-CT showed multiple metastases, including bone, para-aortic lymph nodes, and pleura, pembrolizumab was initiated as a second-line treatment. After two courses of pembrolizumab, the patient's symptoms remarkably improved, and the abnormal systemic accumulation on PET-CT almost disappeared. After 26 months of continuous treatment with pembrolizumab, the patient remains disease-free. Several studies have been reported that focused on tumor subtypes and programmed cell death ligand 1 (PD-L1)-positive tumor cells as candidate biomarkers in relation to the efficacy of pembrolizumab. The higher proportion of PD-L1-positive cells in the sarcomatoid subtype may have resulted in favorable oncological outcomes compared with pure UC.

A case report of immune checkpoint inhibitor-related myositis and cholangitis induced by pembrolizumab.

Key Clinical Message: Rare but severe, immune-related adverse events such as myositis and sclerosing cholangitis can occur with immune checkpoint inhibitors in lung cancer treatment. This case report highlights their co-occurrence after pembrolizumab treatment, indicating the need for vigilance and management strategies in immune checkpoint inhibitors therapy. Abstract: Immune checkpoint inhibitors (ICI) are used in advanced treatment of lung cancer but can lead to immune-related adverse events. ICI-related myositis and cholangitis are rare, and their combination has not been previously reported. Here, we report the first case of ICI-related myositis and sclerosing cholangitis. A patient with stage IV lung adenocarcinoma who received one cycle of pembrolizumab with cisplatin and pemetrexed developed myositis. Treatment with prednisolone improved the myositis, but the patient subsequently developed cholangitis. The patient did not respond to a regimen of prednisolone, mycophenolate mofetil, and azathioprine, and eventually died due to worsening lung cancer. An autopsy confirmed the presence of ICI-related myositis and sclerosing cholangitis.

Prognostic Impact of the Administration of Antibiotics and Proton Pump Inhibitors in Immune Checkpoint Inhibitor Combination Therapy for Advanced Renal Cell Carcinoma.

Background/Aim: The prognostic impact of the administration of antibiotics and proton pump inhibitors (PPIs) in immune checkpoint inhibitor (ICI) therapy for advanced cancer has recently been documented. However, how these drugs affect the outcomes of first-line ICI combination therapy for advanced renal cell carcinoma (RCC) remains unclear. Patients and Methods: We retrospectively evaluated the data of 128 patients with RCC who received first-line ICI combination therapy. The patients were grouped according to their history of antibiotics and PPIs use one month before the initiation of ICI combination therapy. Progression-free survival (PFS), overall survival (OS), and objective response rate (ORR) after ICI combination therapy were compared between patients treated with and without antibiotics or PPIs. Results: Of the 128 patients, 30 (23%) and 44 (34%) received antibiotics and PPIs, respectively. Patients treated with antibiotics exhibited shorter PFS and OS compared to those who did not receive antibiotics (median PFS: 4.9 vs. 16.1 months, p<0.0001; OS: 20.8 vs. 49.0 months, p=0.0034). Multivariate analyses showed that antibiotic administration was an independent predictor of shorter PFS (hazard ratio: 2.54: p=0.0002) and OS (hazard ratio: 2.56: p=0.0067) after adjusting for other covariates. In contrast, there were no significant differences in either PFS or OS between patients who received PPIs and those who did not. (PFS: p=0.828; OS: p=0.105). Conclusion: Antibiotics administration before ICI combination therapy was negatively associated with outcomes of first-line ICI combination therapy for advanced RCC. Therefore, careful monitoring is required for potentially high-risk patients undergoing ICI combination therapy.

Metastatic Disease Mimicking Osteomyelitis in the Foot.

Cervical cancer most commonly spreads hematogenously to the lungs, liver, and bone. However, it rarely metastasizes to the foot. There is only one other case of cervical cancer with metastasis to the foot. In addition, the initial imaging of metastatic disease has difficulty in differentiating from infectious or other inflammatory processes, particularly in a clinical setting highly suspicious of infectious sources. Here, we present a rare case of cervical cancer metastasizing to the calcaneus masquerading as osteomyelitis, highlighting the importance of diagnostic imaging in conjunction with histological confirmation.

Complete Response to Pembrolizumab in Stage IV Alveolar Soft Part Sarcoma After Failure of Four Lines of Treatment: A Case Report and Literature Review.

Alveolar soft part sarcoma (ASPS) is a rare malignant tumor that manifests as a slow-growing soft tissue mass and frequently presents with distant metastasis. The prognosis is variable, and complete remission of metastatic disease has rarely been reported. Our patient was diagnosed with metastatic ASPS at the age of 17, with a primary forearm lesion and metastasis to the lungs. She underwent surgical resection of her forearm mass, followed by adjuvant chemotherapy and radiation to target the lung metastasis. Over the next decade, she had a complicated course of treatment. Her disease continued to slowly progress despite treatment with sunitinib, pazopanib, and a combination of docetaxel and gemcitabine. We eventually treated her with immune checkpoint inhibitors (ICIs). Pembrolizumab, initially in combination with bevacizumab and later as monotherapy, resulted in significant tumor shrinkage, especially in the pulmonary lesions, within the first three months. Subsequent imaging reported complete remission within 15 months and no disease recurrence at her three-year follow-up. Our case highlights one of the very few reported cases of complete remission achieved in metastatic ASPS after treatment with ICIs. ICIs could offer hope for disease remission in advanced ASPS, a rare malignancy that has proven difficult to treat successfully in the past. More studies need to be conducted to further evaluate the efficacy and any associated predictors of successful treatment.

A 1-year follow-up study on checkpoint inhibitor-induced colitis: results from a European consortium.

BACKGROUND: Data regarding the clinical outcome of patients with immune checkpoint inhibitor (ICI)-induced colitis are scant. We aimed to describe the 12-month clinical outcome of patients with ICI-induced colitis. MATERIALS AND METHODS: This was a retrospective, European, multicentre study. Endoscopy/histology-proven ICI-induced colitis patients were enrolled. The 12-month clinical remission rate, defined as a Common Terminology Criteria for Adverse Events diarrhoea grade of 0-1, and the correlates of 12-month remission were assessed. RESULTS: Ninety-six patients [male:female ratio 1.5:1; median age 65 years, interquartile range (IQR) 55.5-71.5 years] were included. Lung cancer (41, 42.7%) and melanoma (30, 31.2%) were the most common cancers. ICI-related gastrointestinal symptoms occurred at a median time of 4 months (IQR 2-7 months). An inflammatory bowel disease (IBD)-like pattern was present in 74 patients (77.1%) [35 (47.3%) ulcerative colitis (UC)-like, 11 (14.9%) Crohn's disease (CD)-like, 28 (37.8%) IBD-like unclassified], while microscopic colitis was present in 19 patients (19.8%). As a first line, systemic steroids were the most prescribed drugs (65, 67.7%). The 12-month clinical remission rate was 47.7 per 100 person-years [95% confidence interval (CI) 33.5-67.8). ICI was discontinued due to colitis in 66 patients (79.5%). A CD-like pattern was associated with remission failure (hazard ratio 3.84, 95% CI 1.16-12.69). Having histopathological signs of microscopic colitis (P = 0.049) and microscopic versus UC-/CD-like colitis (P = 0.014) were associated with a better outcome. Discontinuing the ICI was not related to the 12-month remission (P = 0.483). Four patients (3.1%) died from ICI-induced colitis. CONCLUSIONS: Patients with IBD-like colitis may need an early and more aggressive treatment. Future studies should focus on how to improve long-term clinical outcomes.

What prognostic factors have impacted the efficacy of immune checkpoint inhibitors in patients with recurrent or metastatic oral cancer?

BACKGROUND: Immune checkpoint inhibitors (ICIs) are widely adapted for recurrent or metastatic head and neck cancer (RM-HNC), and various studies on its prognostic factors have been reported. We aimed to elucidate the prognostic factors of ICI treatment for RM oral cancer (RM-OC) in a retrospective study. METHODS: We retrospectively reviewed patients with RM-OC treated with ICIs (nivolumab and pembrolizumab) at our department from May 2017 to February 2023. The objective response rate (ORR) for ICI treatment and the relationship between several potential prognostic factors, progression-free survival (PFS), and overall survival (OS) were analyzed statistically. RESULTS: The investigation enrolled 31 patients, 16 with nivolumab and 15 with pembrolizumab. There were no significant differences in the ORR or disease control rate between the nivolumab and pembrolizumab groups (p = 0.4578 and 0.2524). In multivariate analysis, the prognostic nutritional index (PNI) and C-reactive protein to albumin ratio (CAR) exhibited statistical correlations with PFS, whereas the use of antibiotics and proton pump inhibitors (PPIs), neutrophil to lymphocyte ratio (NLR), and PNI demonstrated statistical associations with OS. CONCLUSION: Our findings imply that the use of antibiotics and PPIs, which can modify the gut microbiota, may also serve as a prognostic determinant for ICI treatment in RM-OC, consistent with previous studies. Additionally, PNI may be essential in affecting the survival rates of both PFS and OS and could be an exceedingly valuable inflammatory biomarker for RM-OC.

Failure of the PD-1 Blocking Agent Pembrolizumab to Benefit a Patient with Renal Squamous Cell Cancer.

Introduction: Renal squamous cell carcinoma (SCC) is a neoplasm with an extremely rare occurrence compared to other renal malignancies. The classic presentation includes a palpable mass and flank pain; however, the presentation is seldom non-specific. Our study describes the significance of programmed death ligand-1 (PD-L1) expression in renal cancer and its association with clinical outcomes, alongside available treatment options. Case description: An 80-year-old female with a history of hypertension and cerebral aneurysm presented with right flank pain and blood in urine and was diagnosed with pyelonephritis and left renal mass/phlegmon. A biopsy revealed SCC of the kidney with metastasis to the lung and aortocaval lymph node. Positron emission tomography (PET) scan confirmed malignancy in the kidney and lung. Treatment with pemrolizumab and carboplatin plus paclitaxel was initiated but poorly tolerated as the haemoglobin dropped rapidly. Conclusion: SCC poses a diagnostic challenge due to its rarity and non-specific symptoms, often leading to advanced stage diagnosis. PD-L1 expression is pivotal in assessing tumour aggressiveness and prognosis. PD-L1 inhibitors offer promise, but their efficacy in renal SCC warrants further investigation. Radical nephrectomy and systemic chemotherapy show potential in advanced cases, necessitating vigilant management of treatment-related side effects. This case emphasises the need for ongoing research to refine therapeutic approaches and enhance outcomes in renal SCC patients. LEARNING POINTS: PD-L1 expression is pivotal in assessing tumour aggressiveness and prognosis of renal cell carcinoma.PD-L1 inhibitors hold promise as a therapeutic intervention in renal squamous cancer.Radical nephrectomy and systemic chemotherapy show potential in managing advanced renal cancer.

Unforeseen Complications of Pembrolizumab in Breast Reconstruction Post-Mastectomy.

A 53-year-old post-menopausal Indian female presented with invasive ductal carcinoma, treated with neoadjuvant chemotherapy and pembrolizumab due to a PD-L1 combined positive score of 5. Following a right mastectomy and axillary dissection, she received a breast expander and AlloDerm™ graft. After resuming pembrolizumab and paclitaxel postoperatively, she developed severe breast redness and high-grade fever, necessitating expander removal due to suspected pembrolizumab-induced complications. This case underscores the unique and severe adverse effects of pembrolizumab on breast reconstruction, highlighting the need for careful monitoring and management in patients undergoing similar treatments. LEARNING POINTS: Among patients with early triple-negative breast cancer, the combination of pembrolizumab with neoadjuvant chemotherapy enhances outcomes compared to chemotherapy alone.Early recognition is essential for managing pembrolizumab-induced complications, as demonstrated by the need for expander removal and debridement in this case.The unique adverse effects observed in this case underscore the importance of tailoring cancer treatment plans to individual patients, taking into account the potential risks associated with immunotherapy in the context of reconstructive surgery.

Pembrolizumab with external radiation therapy effectively controlled TMB-high unresectable recurrent parathyroid cancer: a case report with review of literature.

Parathyroid cancer (PC) is extremely resistant to chemotherapy and radiotherapy (RT), but hormonally functional by producing excessive parathyroid hormone (PTH), causing remarkable hypercalcemia even in biochemical disease recurrence. Accordingly, management of hypercalcemia by calcimimetics and bisphosphonates has been main treatment for unresectable PC. Here, we report a case of unresectable tumor mutational burden (TMB)-high recurrent PC that has been effectively controlled by pembrolizumab (PEM) with RT. A 48-year-old male patient, with previous history of left single parathyroidectomy for primary hyperparathyroidism, underwent surgeries for recurrent hyperparathyroidism at 47 and 48 years of age, and was pathologically diagnosed with PC. He was referred to our hospital due to persistent hypercalcemia and elevated PTH. The recurrent tumors were identified in the superior mediastinum and radically resected, then the hyperparathyroidism was improved. A FoundationOne® CDx of the specimen called TMB-high. He demonstrated recurrent hyperparathyroidism at 49 years of age, and underwent a gross curative resection. However, hyperparathyroidism achieved only insufficient improvement, indicating biochemical residual cancer cells. PEM treatment was initiated in combination with RT to the left central-lateral neck and superior mediastinum. He successfully achieved evocalcet and zoledronate withdrawal, and the PTH level improvement was continuously observed for 8 months at present, with only grade 2 subclinical hypothyroidism. Interestingly, leukocyte fraction ratios were reversed corresponding to disease improvement. A combination of PEM and RT is a promising treatment of unresectable TMB-high PC. Recent evidence on the immunomodulatory effect of RT provides the rationale for the combination of RT and PEM.