This study demonstrates that wearable-based remote patient monitoring combined with a self-supervised contrastive deep learning model can detect and predict serious clinical complications (SCC) up to 48 hours before clinical diagnosis in patients undergoing treatment for hematological malignancies. The patient-specific approach achieved an AUROC of 0.93 for all SCC and 0.94 for infectious SCC, significantly outperforming the patient-non-specific approach. These findings provide proof of principle that continuous wearable monitoring can enable early detection of life-threatening complications in both inpatient and outpatient oncology settings.