Targeting the DNA damage response in hematological malignancies

Deregulation of the DNA damage response (DDR) plays a critical role in the pathogenesis and progression of many cancers. The dependency of certain cancers on DDR pathways has enabled exploitation of such through synthetically lethal relationships e.g., Poly ADP-Ribose Polymerase (PARP) inhibitors for BRCA deficient ovarian cancers. Though lagging behind that of solid cancers, DDR inhibitors (DDRi) are being clinically developed for haematological cancers. Furthermore, a high proliferative index characterize many such cancers, suggesting a rationale for combinatorial strategies targeting DDR and replicative stress. In this review, we summarize pre-clinical and clinical data on DDR inhibition in haematological malignancies and highlight distinct haematological cancer subtypes with activity of DDR agents as single agents or in combination with chemotherapeutics and targeted agents. We aim to provide a framework to guide the design of future clinical trials involving haematological cancers for this important class of drugs.

Prevention of adhesions by Seprafilm, an absorbable adhesion barrier: an incisional hernia model in rats

Adhesion formation, which is almost inevitable following incisional hernia repair with prosthetic mesh, may lead to intestinal obstruction and enterocutaneous fistulae. Physical barriers, namely carboxymethylcellulose and hyaluronic acid, have been reported to lessen the intra-abdominal adhesions. To evaluate the effects of Seprafilm (Genzyme Corp., Cambridge, MA), a bioresorbable, translucent membrane composed of carboxymethylcellulose and hyaluronic acid, in the presence of a foreign body such as polypropylene mesh, an incisional hernia model in rats was used. Twenty-four male rats were divided into two groups: control (12) and Seprafilm (12). A defect, measuring 1.5 x 2.5 cm, was created in each animal. Control animals had the polypropylene mesh sutured to the defect, whereas in the other group, two membranes of Seprafilm were laid over the abdominal viscera before repair with polypropylene mesh. Half of the animals from each group were killed at postoperative day 7 and remaining half at day 30 for adhesion scoring and histological evaluation of wound healing. Seprafilm animals had fewer adhesions compared with control animals (P = 0.0008). Seprafilm had no adverse effect on wound healing. This membrane seems to have the potential to lessen the adhesion-related morbidity following incisional hernia repair.

Effects of physical barriers in prevention of adhesions: an incisional hernia model in rats

BACKGROUND

Adhesion formation between viscera and mesh is almost inevitable following incisional hernia repair with prosthetic mesh. Such adhesions may lead to intestinal obstruction and enterocutaneous fistulae formation and make further laparotomies extremely difficult. Sodium carboxymethylcellulose (SCMC) and Interceed TC7 (oxidized regenerated cellulose) as physical barriers have been shown to be effective in reducing postoperative adhesions.

MATERIALS AND METHODS

To evaluate the effects of SCMC and Interceed TC7, we used an incisional hernia model in rats. A ventral abdominal defect (15 x 25 mm) was created in each of 36 male rats which were then divided into three equal groups. In Group I (control) the defect was repaired with polypropylene mesh (PPM) only; in Group II the defect was repaired after a layer of Interceed TC7 was laid over the viscera with Interceed TC7-covered PPM; in Group III the defect was repaired after a layer of SCMC was laid over the viscera with SCMC-coated PPM. Six of the animals from each group were sacrificed at Postoperative Day 7 and the adhesions were scored. The remaining 6 were sacrificed at Day 30 and histological evaluation was made in addition to the adhesion score.

RESULTS

Animals in the SCMC-treated group developed significantly less adhesions (P = 0.0002) compared with control and Interceed TC7-treated groups. However, histological analysis revealed poor fibroblast proliferation with impaired wound healing in the SCMC group.

CONCLUSION

SCMC prevented adhesion formation but seriously impaired wound healing, and Interceed TC7 was ineffective in preventing adhesion in this model.