Off-target autophagy inhibition by SHP2 allosteric inhibitors contributes to their anti-tumor activity in RAS-driven cancers.

Aberrant activation of RAS-MAPK signaling is common in cancer, and efforts to inhibit pathway components have yielded drugs with promising clinical activities. Unfortunately, treatment-provoked adaptive resistance mechanisms inevitably develop, limiting their therapeutic potential. As a central node essential for receptor tyrosine kinase mediated RAS activation, SHP2 has emerged as an attractive cancer target. Consequently, many SHP2 allosteric inhibitors are now in clinical testing. Here we discovered a previously unrecognized off-target effect associated with SHP2 allosteric inhibitors. We found that these inhibitors accumulate in the lysosome and block autophagic flux in a SHP2-independent manner. We showed that off-target autophagy inhibition by SHP2 allosteric inhibitors contributes to their anti-tumor activity. We also demonstrated that SHP2 allosteric inhibitors harboring this off-target activity not only suppress oncogenic RAS signaling but also overcome drug resistance such as MAPK rebound and protective autophagy in response to RAS-MAPK pathway blockage. Finally, we exemplified a therapeutic framework that harnesses both the on- and off-target activities of SHP2 allosteric inhibitors for improved treatment of mutant RAS driven and drug resistant malignancies such as pancreatic and colorectal cancers. Brief Summary: SHP2 allosteric inhibitors elicit off-target autophagy blockade that can be exploited for improved treatment of RAS-driven and drug-resistant cancers.

Discovery of a selective TC-PTP degrader for cancer immunotherapy.

T-cell protein tyrosine phosphatase (TC-PTP), encoded by PTPN2, has emerged as a promising target for cancer immunotherapy. TC-PTP deletion in B16 melanoma cells promotes tumor cell antigen presentation, while loss of TC-PTP in T-cells enhances T-cell receptor (TCR) signaling and stimulates cell proliferation and activation. Therefore, there is keen interest in developing TC-PTP inhibitors as novel immunotherapeutic agents. Through rational design and systematic screening, we discovered the first highly potent and selective TC-PTP PROTAC degrader, TP1L, which induces degradation of TC-PTP in multiple cell lines with low nanomolar DC50s and >110-fold selectivity over the closely related PTP1B. TP1L elevates the phosphorylation level of TC-PTP substrates including pSTAT1 and pJAK1, while pJAK2, the substrate of PTP1B, is unaffected by the TC-PTP degrader. TP1L also intensifies interferon gamma (IFN-γ) signaling and increases MHC-I expression. In Jurkat cells, TP1L activates TCR signaling through increased phosphorylation of LCK. Furthermore, in a CAR-T cell and KB tumor cell co-culture model, TP1L enhances CAR-T cell mediated tumor killing efficacy through activation of the CAR-T cells. Thus, we surmise that TP1L not only provides a unique opportunity for in-depth interrogation of TC-PTP biology but also serves as an excellent starting point for the development of novel immunotherapeutic agents targeting TC-PTP.

N-Glycosylation Facilitates 4-1BB Membrane Localization by Avoiding Its Multimerization.

Leveraging the T cell immunity against tumors represents a revolutionary type of cancer therapy. 4-1BB is a well-characterized costimulatory immune receptor existing on activated T cells and mediating their proliferation and cytotoxicity under infectious diseases and cancers. Despite the accumulating interest in implementing 4-1BB as a therapeutic target for immune-related disorders, less is known about the pattern of its intracellular behaviors and regulations. It has been previously demonstrated that 4-1BB is heavily modified by N-glycosylation; however, the biological importance of this modification lacks detailed elucidation. Through biochemical, biophysical, and cell-biological approaches, we systematically evaluated the impact of N-glycosylation on the ligand interaction, stability, and localization of 4-1BB. We hereby highlighted that N-glycan functions by preventing the oligomerization of 4-1BB, thus permitting its membrane transportation and fast turn-over. Without N-glycosylation, 4-1BB could be aberrantly accumulated intracellularly and fail to be sufficiently inserted in the membrane. The N-glycosylation-guided intracellular processing of 4-1BB serves as the potential mechanism explicitly modulating the "on" and "off" of 4-1BB through the control of protein abundance. Our study will further solidify the understanding of the biological properties of 4-1BB and facilitate the clinical practice against this promising therapeutic target.

Are We Overtreating Patients With T1a HER2+ Breast Cancer? An Analysis of the National Cancer Database.

INTRODUCTION: The potential benefit of systemic therapy in patients with T1a HER2+ cancers is not well understood, and no consensus guidelines exist. We sought to investigate practice patterns of chemotherapy use in this population. METHODS: From the National Cancer Database (2013-2018), we identified female patients with HER2+ cancers staged as cT1aN0 or pT1aN0 and stratified by receipt of chemotherapy. Using univariate and multivariable analyses we assessed the clinicopathologic features associated with the receipt of chemotherapy. We also compared rates of overall survival (OS). RESULTS: Of 5176 women with cT1aN0 HER2+ cancers, 88 (2%) received neoadjuvant chemotherapy. Younger age and hormone-receptor (HR) negative tumors were factors independently associated with receipt of neoadjuvant chemotherapy (all P < .001). Of 11,688 women with pT1aN0 HER2+ cancers, 5,588 (48%) received adjuvant chemotherapy. Rates of use increased over the analysis period from 39% in 2013 to 53% in 2018 (P < .001). Factors independently associated with receipt of adjuvant chemotherapy included younger age, having a poorly differentiated tumor, exhibiting lymphovascular invasion, undergoing adjuvant radiation (all P < .001). There were no differences in OS when comparing those who did and did not receive chemotherapy in either group. CONCLUSIONS: The use of chemotherapy in patients with HER2+ T1a cancers is increasing over time and is, as expected, more common among patients with unfavorable clinicopathologic features. Since no prognostic algorithm currently exists, more prospective data is needed to understand which of these patients may derive benefit from systemic therapy and which may safely avoid the morbidity of chemotherapy.

Risk-reducing surgery in PALB2 mutations carriers with breast cancer: a case series and literature review.

Background: Inherited germline mutations in PALB2 are known to predispose patients to a higher risk of breast, ovarian and pancreatic cancer with an estimated risk of developing breast cancer in over half of all affected women by age 80 years. Current guidelines for screening patients with PALB2 mutations include annual mammograms beginning at age 30 years and consideration of breast magnetic resonance imaging (MRI) and tomosynthesis. Existing evidence regarding risk-reducing surgery with mastectomy is insufficient to make a definitive recommendation to patients. In this case series, we describe the presentation and management of 5 patients with unilateral breast cancer and PALB2 mutations. To our knowledge, this is the first reported case series discussing the role of contralateral risk-reducing mastectomy (CRRM) in breast cancer patients with PALB2 mutations. The aim of our study was to evaluate the challenges in managing breast cancer risk in patients with PALB2 pathogenic variants with illustration through real-world clinical cases and a review of the literature. Methods: In this retrospective observational study, we present 5 patients with PALB2 mutations between the ages of 29 and 61 years who were diagnosed with breast cancer and underwent surgical management of their breast cancer at our institution between November 2020 and March 2022. Through their clinical courses and a literature review, we discuss the role of CRRM in breast cancer patients with PALB2 gene mutations. Results: Out of the 5 patients, 3 patients underwent CRRM and 2 patients chose unilateral surgery for their breast cancer and active surveillance for the contralateral breast. Of the 3 patients who underwent CRRM, 1 patient experienced a surgical complication from reconstruction on the prophylactic side. None of the patients developed any recurrences with an average length of follow up of 15.4 months. Conclusions: Based on our experience and the currently available literature, CRRM in patients with a PALB2 mutation should be performed on a case-by-case basis through a shared decision-making process taking into consideration overall risk, family history, patient preference and quality of life.

Triple negative breast cancer and reconstruction: Predictors of recurrence, complications, and mortality.

BACKGROUND: Only 42% of all breast cancer patients undergoing mastectomy elect for breast reconstruction. OBJECTIVE: We evaluate factors impacting complications, recurrence, and mortality in triple-negative breast cancer (TNBC) patients undergoing reconstruction. METHODS: Reconstructive TNBC patients at a single institution from 2010 to 2020 were retrospectively reviewed. Patient demographics, cancer characteristics, reconstruction choice, and complications were collected. Statistical significance was defined at p < 0.05. RESULTS: A total of 131 patients were identified. Average age was 47.8 years, 50.4% were Caucasian and 36.4% were African American. Most patients had invasive ductal carcinoma (90.8%), and most underwent nipple-sparing (41.2%) or skin-sparing (38.9%) mastectomies. Twenty-one patients (16.0%) experienced postoperative complications. Patients with complications tended to be older (52.1 versus 46.9 years, p = 0.052). At mean follow-up of 52.1 months, 14.5% experienced cancer recurrence and 5.3% died. Deceased patients were significantly younger at diagnosis (42.2 versus 48.5 years, p = 0.008) and had a lower BMI compared to surviving patients (21.2 versus 26.9 kg/m2; p = 0.014). Patients younger than age 45 years had higher Ki-67 than those older than 45 years (80.0% versus 60.0%, p = 0.013). Outcomes in autologous- versus implant-based reconstruction were not significantly different. CONCLUSIONS: In TNBC post-mastectomy reconstruction patients, age and BMI were predictors of mortality while race, smoking history, reconstruction choice, or type of implant-based reconstruction had no significant effect on these outcomes. SYNOPSIS: The purpose of this study is to evaluate factors that impact complications, recurrence, and mortality in triple negative breast cancer (TNBC) patients undergoing reconstruction. We identified BMI, neoadjuvant chemotherapy, and age as predictors of complications, recurrence, and mortality in TNBC.

Xylose fermentation by genetically modified Saccharomyces cerevisiae 259ST in spent sulfite liquor.

Spent sulfite pulping liquor (SSL) is a high-organic content byproduct of acid bisulfite pulp manufacture which is fermented to make industrial ethanol. SSL is typically concentrated to 240 g/l (22% w/w) total solids prior to fermentation, and contains up to 24 g/l xylose and 30 g/l hexose sugars, depending upon the wood species used. The xylose present in SSL is difficult to ferment using natural xylose-fermenting yeast strains due to the presence of inhibitory compounds, such as organic acids. Using sequential batch shake flask experiments, Saccharomyces cerevisiae 259ST, which had been genetically modified to ferment xylose, was compared with the parent strain, 259A, and an SSL adapted strain, T2, for ethanol production during SSL fermentation. With an initial SSL pH of 6, without nutrient addition or SSL pretreatment, the ethanol yield ranged from 0.32 to 0.42 g ethanol/g total sugar for 259ST, compared to 0.15-0.32 g ethanol/g total sugar for non-xylose fermenting strains. For most fermentations, minimal amounts of xylitol (<1 g/l) were produced, and glycerol yields were approximately 0.12 g glycerol/g sugar consumed. By using 259ST for SSL fermentation up to 130% more ethanol can be produced compared to fermentations using non-xylose fermenting yeast.

Colorectal cancer screening: practices and attitudes of gastroenterologists, internists and surgeons.

BACKGROUND: The Canadian Task Force on Preventive Health Care has recommended the use of annual or biennial fecal occult blood testing (FOBT) and flexible sigmoidoscopy in the periodic health examination of asymptomatic people over 50 years of age. Therefore, we decided to ascertain the current colorectal cancer (CRC) screening practices and attitudes of surgeons, gastroenterologists and internists. METHODS: In June 2002 (with a final mailing in December 2002), a questionnaire was sent to all gastroenterologists, internists and surgeons in Alberta. It included items on demographic and practice characteristics, CRC screening practices and opinions about CRC screening. RESULTS: Responses were received from 42 gastroenterologists, 83 internists and 68 surgeons. Overall, 141 of 187 respondents (75.4%, 95% confidence interval [CI] 68.6%-81.4%) recommended that average-risk adults undergo CRC screening. Internists were less likely to recommend screening than either gastroenterologists or surgeons (95% CI for the difference 7.2%-32.8%). The most commonly recommended screening test was colonoscopy (70%), followed by FOBT (65%), flexible sigmoidoscopy (47%) and air-contrast barium enema (31%). Colonoscopy was the only test recommended by 7 (22.6%) of 33 gastroenterologists, 9 (16.4%) of 59 surgeons and 3 (6.1%) of 49 internists. Respondents were more likely to list barriers to the use of colonoscopy (mean 5 barriers) for screening than for either FOBT or flexible sigmoidoscopy (mean 2 barriers for both tests). Only 3 respondents indicated that they themselves would not undergo screening. Colonoscopy was the only screening test that 135 (70.0%) of the 193 would themselves undergo. CONCLUSIONS: The majority of Alberta specialists recommend CRC screening for average-risk adults. Colonoscopy was the most commonly recommended test, despite the perception of more barriers to that technique and the 2001 guidelines prepared by the Canadian Task Force for Preventive Health Care, which did not support colonoscopy.