Sentence: Combinations of alkylating agents and fludarabine or cladribine are also synergistic in producing significantly enhanced activity against refractory lymphoid malignancies , but at the cost of increased haematological toxicity .
Drug combination annotation:
[{'class': 'COMB', 'spans': ['alkylating agents', 'fludarabine'], 'is_context_needed': True}, {'class': 'COMB', 'spans': [0, 2], 'is_context_needed': True}]