We investigated the potential of tumor-infiltrating immune cells (ICs) as predictive or prognostic biomarkers for cervical cancer patients. In total, 38 patients treated with (chemo)radiotherapy and subsequent surgery were included in the current study. This unique treatment schedule makes it possible to analyze IC markers in pretreatment and posttreatment tissue specimens and their changes during treatment. IC markers for T cells (CD3, CD4, CD8 and FoxP3), macrophages (CD68 and CD163) and B cells (CD20), as well as IL33 and PD-L1, were retrospectively analyzed via immunohistochemistry. Patients were grouped in the low score or high score group based on the amount of positive cells on immunohistochemistry. Correlations to pathological complete response (pCR), cause-specific survival (CSS) and metastasis development during follow-up were evaluated. In analysis of pretreatment biopsies, significantly more pCR was seen for patients with CD8 = CD3, CD8 ≥ CD4, positive IL33 tumor cell (TC) scores, IL33 IC < TC and PD-L1 TC ≥5%. Besides patients with high CD8 scores, also patients with CD8 ≥ CD4, CD163 ≥ CD68 or PD-L1 IC ≥5% had better CSS. In the analysis of posttreatment specimens, less pCR was observed for patients with high CD8 or CD163 scores. Patients with decreasing CD8 or CD163 scores between pretreatment and posttreatment samples showed more pCR, whereas those with increasing CD8 or decreasing IL33 IC scores showed a worse CSS. Meanwhile, patients with an increasing CD3 score or stable/increasing PD-L1 IC score showed more metastasis during follow-up. In this way, the intratumoral IC landscape is a promising tool for prediction of outcome and response to (chemo)radiotherapy.K.V. and H.D. contributed equally to this work Additional Supporting Information may be found in the online version of this article.

Dear Editor, Soft-tissue sarcomas (STS) are rare, heterogeneous cancers comprising 1% of adult and 15% of paediatric malignancies. Despite optimal treatment, 50%−80% of patients metastasize, even when they attain a status of minimal residual disease (MRD). MRD is achieved through multimodal treatment involving primary tumour resection with wide negative margins. In metastatic setting, systemic therapies are palliative and response rates are low (15%-20%). 1,2 As a result of these poor outcome data, there is a strong need for translationally relevant patient-derived models.Patient-derived xenografts (PDX) are used to investigate novel therapies and guide personalized treatment response. 3 Yet, many PDX models do not reflect the clinical behaviour of human tumours. 4 For STS, commonly used PDX still fail to predict the clinical efficacy of (novel) drugs and indeed, MRD status and subsequent metastatic progression have been poorly modelled in STS-PDX 5 (Table S1). Moreover, currently available STS-PDX models have not been comparatively assessed. In this study we aimed to address this translational gap by creating PDX that mimic MRD status (MRD-PDX), followed by metastatic relapse and examine the most appropriate model. We first engrafted tumour tissue derived from five high-grade STS patients (Table S2) and resected the subsequent primary tumour at a size of 250-450 mm 3 using limb amputation to obtain negative surgical margins, 6 similar to the patient's treatment (Figure 1A). The impact of the site of transplantation (orthotopic [O-PDX] vs subcutaneous [SC-PDX]) and immunodeficiency status of the host animal (NOD scid gamma [NSG] vs Swiss nu/nu mice) on primary tumour growth, MRD and disease progression (local recurrence and metastasis) were directly compared for four patients (Figure 1B). PDX were followed up to 1 year after tumour resection. MRI monitored primary tumour growth, MRD and metastatic relapse (Figure 1A). Histopathology and copy number variation (CNV) sequencing evaluated tumour characteristics.