Intrinsic tumor resistance to radiotherapy limits the efficacy of ionizing radiation (IR). Sensitizing cancer cells specifically to IR would improve tumor control and decrease normal tissue toxicity. The development of tumor targeting technologies allows for developing potent radiosensitizing drugs. We hypothesized that the anti-tubulin agent monomethyl auristatin E (MMAE), a component of a clinically approved antibody-directed conjugate, could function as a potent radiosensitizer and be selectively delivered to tumors using an activatable cell penetrating peptide targeting matrix metalloproteinases and RGD binding integrins (ACPP-cRGD-MMAE). We evaluated the ability of MMAE to radiosensitize both established cancer cells and a low passage cultured human pancreatic tumor cell line using clonogenic and DNA damage assays. MMAE sensitized colorectal and pancreatic cancer cells to IR in a schedule and dose dependent manner correlating with mitotic arrest. Radiosensitization was evidenced by decreased clonogenic survival and increased DNA double strand breaks in irradiated cells treated with MMAE. MMAE in combination with IR resulted in increased DNA damage signaling and activation of CHK1. To test a therapeutic strategy of MMAE and IR, PANC-1 or HCT-116 murine tumor xenografts were treated with non-targeted free MMAE or tumor targeted MMAE (ACPP-cRGD-MMAE). While free MMAE in combination with IR resulted in tumor growth delay, tumor targeted ACPP-cRGD-MMAE with IR produced a more robust and significantly prolonged tumor regression in xenograft models. Our studies identify MMAE as a potent radiosensitizer. Importantly, MMAE radiosensitization can be localized to tumors by targeted activatable cell penetrating peptides.

This was a cohort analysis evaluating patients with pancreatic adenocarcinoma who presented with or developed ascites. Among the 180 patients analyzed, the use of serial paracenteses and indwelling catheters is a common practice to effect symptom palliation. The complication rate was higher in patients with indwelling catheters. Analyzing ascitic fluid and calculating the serum ascites albumin gradient can help attribute the etiology of the ascites and potentially identify which patients may benefit from diuretics or other intervention. Background Ascites develops in a subset of patients with pancreatic adenocarcinoma (PAC) at presentation or as the disease advances. Limited data exist on the prognostic importance of malignant ascites in PAC. Our hypothesis is that this information will provide an understanding of the natural history and facilitate management decisions. Methods We conducted a retrospective analysis of 180 patients treated at Memorial Sloan Kettering Cancer Center diagnosed between January 1, 2009 and December 31, 2014, with PAC and with ascites either at presentation or that developed during the disease course. Results For the 180 patients, the overall survival was 15 months. The time from diagnosis to ascites presentation was 11 months, and the survival time after ascites development was 1.8 months (range, 1.6–2.3 months; 95% confidence interval). Of 62 patients (34%) who had ascitic fluid analyzed, 36 (58%) had positive cytology. Fifty-one (82%) patients had a serum ascites albumin gradient ≥ 1, and 11 (18%) had serum ascites albumin gradient < 1. Sixty-four (36%) patients had their ascites managed solely by serial paracenteses. A total of 116 patients required a catheter; of these, 108 (93%) had a Tenckhoff catheter, 4 (3%) a Pleurx catheter, 4 (3%) a pigtail catheter, and 1 (1%) a Denver catheter. Eight (7%) patients required 2 catheters to be placed, and in 6 (5%), Tenckhoff catheters had to be removed. The main observed complications were spontaneous bacterial peritonitis in 7 (11%) managed with paracenteses versus 26 (23%) who had a catheter placed, catheter malfunction in 8 (7%), and acute renal failure in 6 (3%). After ascites development, 79 (44%) patients received active anti-cancer therapy, and 101 (56%) patients were managed with supportive care alone. Conclusions In patients with PAC who presented with or developed ascites, serial paracenteses and indwelling catheters are common methods used for providing symptomatic relief. The complication rate was higher with indwelling catheters, primarily related to infection (eg, bacterial peritonitis). Overall, ascites has a significantly negative prognostic import with a short median survival.

Although oncology therapy regimens commonly include radiation and genotoxic drugs, tumour cells typically develop resistance to these interventions. Here we report that treatment of tumours with ionizing radiation or genotoxic drugs drives p21-activated kinase 1 (PAK1)-mediated phosphorylation of CRAF on Serine 338 (pS338) triggering a kinase-independent mechanism of DNA repair and therapeutic resistance. CRAF pS338 recruits CHK2, a cell cycle checkpoint kinase involved in DNA repair, and promotes CHK2 phosphorylation/activation to enhance the tumour cell DNA damage response. Accordingly, a phospho-mimetic mutant of CRAF (S338D) is sufficient to induce the CRAF/CHK2 association enhancing tumour radioresistance, while an allosteric CRAF inhibitor sensitizes tumour cells to ionizing radiation or genotoxic drugs. Our findings establish a role for CRAF in the DNA damage response that is independent from its canonical function as a kinase.

BACKGROUND: Salvage immunochemotherapy followed by high-dose chemotherapy and autologous stem cell transplantation is the standard-of-care second-line treatment for patients with relapsed/refractory diffuse large B-cell lymphoma after first-line R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone). Outcomes after receipt of second-line immunochemotherapy in patients with aggressive B-cell lymphomas who relapse or are refractory to intensive first-line immunochemotherapy regimens (etoposide, prednisone, vincristine, cyclophosphamide, doxorubicin, and rituximab [R-EPOCH], rituximab, hyperfractionated cyclophosphamide, vincristine, doxorubicin, and dexamethasone alternating with methotrexate and cytarabine [R-HyperCVAD], rituximab, cyclophosphamide, vincristine, doxorubicin, and high-dose methotrexate alternating with ifosfamide, etoposide, and cytarabine [R-CODOX-M/IVAC]) remain unknown. METHODS: Outcomes of patients with non-Burkitt, aggressive B-cell lymphomas and relapsed/refractory disease after first-line treatment with intensive immunochemotherapy regimens who received platinum-based second-line immunochemotherapy were reviewed retrospectively. Analyses were performed to determine progression-free survival (PFS) and overall survival (OS) from the time of receipt of second-line immunochemotherapy. RESULTS: In total, 195 patients from 19 academic centers were included in the study. The overall response rate to second-line immunochemotherapy was 44%, with a median PFS of 3 months and a median OS of 8 months. Patients with early treatment failure (primary refractory or relapse <12 months from completion of first-line therapy) experienced inferior median PFS (2.8 vs 23 months; P < .001) and OS (6 months vs not reached; P < .001) compared with patients with late treatment failure. Although the 17% of patients with early failure who achieved a complete response to second-line immunochemotherapy experienced prolonged survival, this outcome could not be predicted by clinicopathologic features at the start of second-line immunochemotherapy. CONCLUSIONS: Patients with early treatment failure after intensive first-line immunochemotherapy experience poor outcomes after receiving standard second-line immunochemotherapy. The use of standard-of-care or experimental therapies currently available in the third-line setting and beyond should be investigated in the second-line setting for these patients.