Pushing the limits of immune-related response: a case of "extreme pseudoprogression"

Immune response evaluation criteria in solid tumors for assessment of atypical responses after immunotherapy

In 2017, immune response evaluation criteria in solid tumors (iRECIST) were introduced to validate radiologic and clinical interpretations and to better analyze tumor’s response to immunotherapy, considering the different time of following and response, between this new therapy compared to the standard one. However, even if the iRECIST are worldwide accepted, to date, different aspects should be better underlined and well reported, especially in clinical practice. Clinical experience has demonstrated that in a non-negligible percentage of patients, it is challenging to determine the correct category of response (stable disease, progression disease, partial or complete response), and consequently, to define which is the best management for those patients. Approaching radiological response in patients who underwent immunotherapy, a new uncommon kind of target lesions behavior was found. This phenomenon is mainly due to the different mechanisms of action of immunotherapeutic drug. Therefore, new groups of response have been described in clinical practice, defined as “atypical responses,” and categorized into three new groups: pseudoprogression, hyperprogression, and dissociated response. This review summarizes and reports these patterns, helping clinicians and radiologists get used to atypical responses, in order to identify patients that respond best to treatment.

Expectoration of tonsillar metastasis of pulmonary pleomorphic carcinoma after pseudoprogression: A case report

Pulmonary pleomorphic carcinoma is a rare malignant tumor that grows rapidly and has a poor prognosis. Although no effective treatments have so far been established, immune checkpoint inhibitors (ICIs) have shown clinical improvement in some cases of pleomorphic carcinoma. However, pseudoprogression is a major concern for treatment of this carcinoma using ICIs. Here, we report the case of a 61‐year‐old man who was diagnosed with large cell carcinoma of the lung with brain metastases. Systemic chemotherapy comprising carboplatin and pemetrexed was administered as a first‐line therapy; however, disease progression was observed. A tonsillar lesion grew rapidly after the administration of nivolumab as a second‐line therapy. Tracheostomy was planned to avoid suffocation, but the patient naturally expectorated the tumor. Pathological examination revealed that it was a palatine tonsillar metastasis of pulmonary pleomorphic carcinoma with infiltration of CD8+/CD4‐ lymphocytes and necrosis. The primary lesion expanded after nivolumab administration and shrank with no additional nivolumab administration. We therefore concluded that pseudoprogression caused expectoration of the tonsillar metastasis. Hence, ICIs can cause serious adverse events due to pseudoprogression.

Atypical Response Patterns in Renal Cell Carcinoma Treated with Immune Checkpoint Inhibitors-Navigating the Radiologic Potpourri

BACKGROUND

Atypical response patterns have been a topic of increasing relevance since the advent of immune checkpoint inhibitors (ICIs), challenging the traditional RECIST (Response Evaluation Criteria in Solid Tumors) method of tumor response assessment. Newer immune-related response criteria can allow for the evolution of radiologic pseudoprogression, but still fail to capture the full range of atypical response patterns encountered in clinical reporting.

METHODS

We did a detailed lesion-by-lesion analysis of the serial imaging of 46 renal cell carcinoma (RCC) patients treated with ICIs with the aim of capturing the full range of radiologic behaviour.

RESULTS

Atypical response patterns observed included pseudoprogression (n = 15; 32.6%), serial pseudoprogression (n = 4; 8.7%), dissociated response (n = 22; 47.8%), abscopal response (n = 9; 19.6%), late response (n = 5; 10.9%), and durable response after cessation of immunotherapy (n = 2; 4.3%). Twenty-four of 46 patients (52.2%) had at least one atypical response pattern and 18 patients (39.1%) had multiple atypical response patterns.

CONCLUSIONS

There is a high incidence of atypical response patterns in RCC patients receiving ICIs and the study contributes to the growing literature on the abscopal effect. The recognition of these interesting and overlapping radiologic patterns challenges the oncologist to tweak treatment options such that the clinical benefits of ICIs are potentially maximized.

Comparison of Radiological Tumor Response Based on iRECIST and RECIST 1.1 in Metastatic Clear-Cell Renal Cell Carcinoma Patients Treated with Programmed Cell Death-1 Inhibitor Therapy

Objective

To evaluate the radiological tumor response patterns and compare the response assessments based on immune-based therapeutics Response Evaluation Criteria in Solid Tumors (iRECIST) and RECIST 1.1 in metastatic clear-cell renal cell carcinoma (mccRCC) patients treated with programmed cell death-1 (PD-1) inhibitors.

Materials and Methods

All mccRCC patients treated with PD-1 inhibitors at Henan Cancer Hospital, China, between January 2018 and April 2019, were retrospectively studied. A total of 30 mccRCC patients (20 males and 10 females; mean age, 55.6 years; age range, 37–79 years) were analyzed. The target lesions were quantified on consecutive CT scans during therapy using iRECIST and RECIST 1.1. The tumor growth rate was calculated before and after therapy initiation. The response patterns were analyzed, and the differences in tumor response assessments of the two criteria were compared. The intra- and inter-observer variabilities of iRECIST and RECIST 1.1 were also analyzed.

Results

The objective response rate throughout therapy was 50% (95% confidence interval [CI]: 32.1–67.9) based on iRECIST and 30% (95% CI: 13.6–46.4) based on RECIST 1.1. The time-to-progression (TTP) based on iRECIST was longer than that based on RECIST 1.1 (median TTP: not reached vs. 170 days, p = 0.04). iRECIST and RECIST 1.1 were discordant in 8 cases, which were evaluated as immune-unconfirmed PD based on iRECIST and PD based on RECIST 1.1. Six patients (20%, 6/30) had pseudoprogression based on iRECIST, of which four demonstrated early pseudoprogression and two had delayed pseudoprogression. Significant differences in the tumor response assessments based on the two criteria were observed (p < 0.001). No patients demonstrated hyperprogression during the study period.

Conclusion

Our study confirmed that the iRECIST criteria are more capable of capturing immune-related atypical responses during immunotherapy, whereas conventional RECIST 1.1 may underestimate the benefit of PD-1 inhibitors. Pseudoprogression is not rare in mccRCC patients during PD-1 inhibitor therapy, and it may last for more than the recommended maximum of 8 weeks, indicating a limitation of the current strategy for immune response monitoring.

The potential mechanism, recognition and clinical significance of tumor pseudoprogression after immunotherapy

As immunotherapy has gained increasing interest as a new foundation for cancer therapy, some atypical response patterns, such as pseudoprogression and hyperprogression, have garnered the attention of physicians. Pseudoprogression is a phenomenon in which an initial increase in tumor size is observed or new lesions appear, followed by a decrease in tumor burden; this phenomenon can benefit patients receiving immunotherapy but often leads to premature discontinuation of treatment owing to the false judgment of progression. Accurately recognizing pseudoprogression is also a challenge for physicians. Because of the extensive attention on pseudoprogression, significant progress has been made. Some new criteria for immunotherapy, such as irRC, iRECIST and imRECIST, were proposed to accurately evaluate the response to immunotherapy. Many new detection indexes, such as ctDNA and IL-8, have also been used to identify pseudoprogression. In this review, the definition, evaluation criteria, mechanism, monitoring, management and prognosis of pseudoprogression are summarized, and diagnostic and treatment processes for patients with progression but with a suspicion of pseudoprogression are proposed; these processes could be helpful for physicians in clinical practice and enhances the understanding of pseudoprogression.

Severe tracheal stenosis after first administration of pembrolizumab rescued by Dumon Y-stent in a lung cancer patient

A 70-year-old woman diagnosed with advanced, non-resectable programmed cell death ligand 1-positive-non-small-cell lung carcinoma was treated with pembrolizumab as first-line therapy. Soon after therapy initiation, she presented with severe dyspnea, and chest computed tomography revealed a soft tissue mass in the lower trachea of the right main bronchus. During bronchoscopy, she became severely hypoxic, and we performed endoscopic tumor ablation and Dumon Y-stent placement. We considered this severe deterioration caused by pseudoprogression, and suggest that it is necessary to perform bronchoscopy and to prepare for the bronchial intervention when treating patients with immune checkpoint inhibitors.

HITM-SIR: phase Ib trial of intraarterial chimeric antigen receptor T-cell therapy and selective internal radiation therapy for CEA+ liver metastases

Effective chimeric antigen receptor-modified T-cell (CAR-T) therapy for liver metastases (LM) will require innovative solutions to ensure efficient delivery and minimization of systemic toxicity. We previously demonstrated the safety of CAR-T hepatic artery infusions (HAI). We subsequently conducted the phase 1b HITM-SIR trial, in which six patients (pts) with CEA⁺ LM received anti-CEA CAR-T HAIs and selective internal radiation therapy (SIRT). The primary endpoint was safety with secondary assessments of biologic activity. Enrolled pts had a mean LM size of 6.4 cm, 4 pts had >10 LM, and pts received an average of two lines of prior systemic therapy. No grade 4 or 5 toxicities were observed, and there were no instances of severe cytokine-release syndrome (CRS) or neurotoxicity. The mean transduction efficiency was 60.4%. Following CAR-T HAI, reduced levels of GM-CSF-R, IDO, and PD-L1 were detected in LM, and serum CEA levels were stable or decreased in all subjects. Median survival time was 8 months (mean 11, range 4-31). Anti-CEA CAR-T HAI with subsequent SIRT was well tolerated, and biologic responses were demonstrated following failure of conventional therapy. HAI of CAR-T was once again confirmed not to be associated with severe CRS or neurotoxicity.

irRECIST for the Evaluation of Candidate Biomarkers of Response to Nivolumab in Metastatic Clear Cell Renal Cell Carcinoma: Analysis of a Phase II Prospective Clinical Trial

PURPOSE

Immune-related RECIST (irRECIST) were designed to capture atypical responses seen with immunotherapy. We hypothesized that, in patients with metastatic clear cell renal cell carcinoma (mccRCC), candidate biomarkers for nivolumab response would show improved association with clinical endpoints capturing atypical responders (irRECIST) compared with standard clinical endpoints (RECISTv1.1).

EXPERIMENTAL DESIGN

Endpoints based on RECISTv1.1 [objective response rate (ORR)/progression-free survival (PFS)] or irRECIST [immune-related ORR (irORR)/immune-related PFS (irPFS)] were compared in patients enrolled in the CheckMate-010 trial. Pretreatment tumors were analyzed by PD-L1 and PD-L2 IHC, and by multiplex immunofluorescence for CD8, PD-1, TIM-3, and LAG-3. T-cell activation signatures were assessed by RNA sequencing.

RESULTS

Median irPFS was significantly longer than median PFS. irORR was not significantly different from ORR, but immune-related progressive disease (irPD) rate was significantly lower than progressive disease (PD) rate. Tumor cell (TC) PD-L1 expression was not associated with PFS or ORR, but patients with TC PD-L1 ≥1% had longer median irPFS and higher irORR. High percentage of CD8⁺ tumor-infiltrating cells (TIC) that are PD-1⁺TIM-3^-LAG-3^- (% CD8⁺PD-1⁺TIM-3^-LAG-3^- TIC) correlated with high levels of T-cell activation and was associated with longer median irPFS and higher irORR. Notably, combination of TC PD-L1 expression with % CD8⁺PD-1⁺TIM-3^-LAG-3^- TIC identified three groups of patients for which irPFS and irORR were significantly different.

CONCLUSIONS

Atypical responders to nivolumab were identified in the CheckMate-010 trial. We observed improved association of candidate biomarkers for nivolumab response with endpoints defined by irRECIST compared with RECISTv1.1. TC PD-L1 expression in combination with PD-1 expression on CD8⁺ TIC may predict outcome on nivolumab in mccRCC.

An undescribed venous pathway intervening between the olfactory fossa and nasal vestibule

PURPOSE

A curvilinear pathway intervening between the olfactory fossa and nasal vestibule has not been well documented. Therefore, the aim of this study was to examine its structure using magnetic resonance imaging (MRI).

METHODS

In total, 84 patients underwent thin-sliced, contrast MRI. Among these patients, 31 underwent additional thin-sliced, sagittal T2-weighted imaging.

RESULTS

A curvilinear pathway intervening between the olfactory fossa and nasal vestibule was delineated on sagittal and coronal imaging in 98% and 82% of patients, respectively. All of these pathways demonstrated communication with the lower limit of the superior sagittal sinus (SSS) or fine venous channels connecting to the SSS in the vicinity of the crista galli. The pathway was identified in the parasagittal regions on both sides with varying lengths, diameters, and curvatures. In 94% of the patients who underwent sagittal T2-weighted imaging, the pathways appeared as linear high-intensity signals. Most pathways were delineated as a single channel coursing extracranially adjacent to the olfactory fossa. In 38% of the patients, post-contrast sagittal images showed variable filling defects between the olfactory bulb and floor of the olfactory fossa, furthermore traversing the venous pathway. Additionally, in 73% of the patients, post-contrast images identified diploic venous channels, variably in the nasal bone and communicating with the venous pathway.

CONCLUSIONS

A curvilinear pathway intervening between the olfactory fossa and nasal vestibule is a consistent venous structure and may function as an extracranial route of cerebrospinal fluid drainage.

irRECIST for the Evaluation of Candidate Biomarkers of Response to Nivolumab in Metastatic Clear Cell Renal Cell Carcinoma: Analysis of a Phase II Prospective Clinical Trial

PURPOSE

Immune-related RECIST (irRECIST) were designed to capture atypical responses seen with immunotherapy. We hypothesized that, in patients with metastatic clear cell renal cell carcinoma (mccRCC), candidate biomarkers for nivolumab response would show improved association with clinical endpoints capturing atypical responders (irRECIST) compared with standard clinical endpoints (RECISTv1.1).

EXPERIMENTAL DESIGN

Endpoints based on RECISTv1.1 [objective response rate (ORR)/progression-free survival (PFS)] or irRECIST [immune-related ORR (irORR)/immune-related PFS (irPFS)] were compared in patients enrolled in the CheckMate-010 trial. Pretreatment tumors were analyzed by PD-L1 and PD-L2 IHC, and by multiplex immunofluorescence for CD8, PD-1, TIM-3, and LAG-3. T-cell activation signatures were assessed by RNA sequencing.

RESULTS

Median irPFS was significantly longer than median PFS. irORR was not significantly different from ORR, but immune-related progressive disease (irPD) rate was significantly lower than progressive disease (PD) rate. Tumor cell (TC) PD-L1 expression was not associated with PFS or ORR, but patients with TC PD-L1 ≥1% had longer median irPFS and higher irORR. High percentage of CD8⁺ tumor-infiltrating cells (TIC) that are PD-1⁺TIM-3^-LAG-3^- (% CD8⁺PD-1⁺TIM-3^-LAG-3^- TIC) correlated with high levels of T-cell activation and was associated with longer median irPFS and higher irORR. Notably, combination of TC PD-L1 expression with % CD8⁺PD-1⁺TIM-3^-LAG-3^- TIC identified three groups of patients for which irPFS and irORR were significantly different.

CONCLUSIONS

Atypical responders to nivolumab were identified in the CheckMate-010 trial. We observed improved association of candidate biomarkers for nivolumab response with endpoints defined by irRECIST compared with RECISTv1.1. TC PD-L1 expression in combination with PD-1 expression on CD8⁺ TIC may predict outcome on nivolumab in mccRCC.

Marked response to nivolumab combined with external radiation therapy for metastatic renal cell carcinoma: report of two cases

Although nivolumab has been regarded as a standard agent for patients with previously treated advanced renal cell carcinoma (RCC), a significant proportion of these patients fail to achieve a response to nivolumab. In recent years, several studies have reported the favorable therapeutic impact of combined therapy with immune checkpoint inhibitors and radiotherapy on a wide variety of advanced malignant tumors, such as melanoma and lung cancer; however, the significance of this combined treatment for advanced RCC patients has not been well characterized. Here, we report two patients with metastatic RCC showing a marked response to nivolumab and external radiation therapy, including one with an abscopal response, after progression on prior treatment with multiple targeted agents. Based on the clinical courses of these two patients suggesting additive or synergistic efficacies on combining radiation with nivolumab, it might be worthwhile to consider the addition of radiotherapy for metastatic RCC patients treated with nivolumab.