Mismatch repair deficiency has contributed to our understanding of carcinogenesis for the past 2 decades and now identifies a subgroup of traditionally chemotherapy-insensitive solid tumors as sensitive to PD-1 blockade. This article seeks to educate oncologists regarding the nature of mismatch repair deficiency, its impact in multiple tumor types, and its implications for predicting the responsiveness of solid tumors to immune checkpoint blockade.

Immunotherapy has changed the standard of care for multiple deadly cancers including lung, head and neck, gastric, and some colorectal cancers. However, single agent immunotherapy has had little effect in pancreatic adenocarcinoma (PDAC). Increasing evidence suggests that the PDAC microenvironment is comprised of an intricate network of signals between immune cells, PDAC cells, and stroma, resulting in an immunosuppressive environment resistant to single agent immunotherapies. In this review, we discuss differences between immunotherapy sensitive cancers and PDAC, the complex interactions between PDAC stroma and suppressive tumor infiltrating cells that facilitate PDAC development and progression, the immunologic targets within these complex networks that are drugable, and data supporting combination drug approaches that modulate multiple PDAC signals, which should lead to improved clinical outcomes.

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BackgroundImmune-checkpoint inhibitor (ICI)-pneumonitis that does not improve or resolve with corticosteroids and requires additional immunosuppression is termed steroid-refractory ICI-pneumonitis. Herein, we report the clinical features, management and outcomes for patients treated with intravenous immunoglobulin (IVIG), infliximab, or the combination of IVIG and infliximab for steroid-refractory ICI-pneumonitis.MethodsPatients with steroid-refractory ICI-pneumonitis were identified between January 2011 and January 2020 at a tertiary academic center. ICI-pneumonitis was defined as clinical or radiographic lung inflammation without an alternative diagnosis, confirmed by a multidisciplinary team. Steroid-refractory ICI-pneumonitis was defined as lack of clinical improvement after high-dose corticosteroids for 48 hours, necessitating additional immunosuppression. Serial clinical, radiologic (CT imaging), and functional features (level-of-care, oxygen requirement) were collected preadditional and postadditional immunosuppression.ResultsOf 65 patients with ICI-pneumonitis, 18.5% (12/65) had steroid-refractory ICI-pneumonitis. Mean age at diagnosis of ICI-pneumonitis was 66.8 years (range: 35–85), 50% patients were male, and the majority had lung carcinoma (75%). Steroid-refractory ICI-pneumonitis occurred after a mean of 5 ICI doses from PD-(L)1 start (range: 3–12 doses). The most common radiologic pattern was diffuse alveolar damage (DAD: 50%, 6/12). After corticosteroid failure, patients were treated with: IVIG (n=7), infliximab (n=2), or combination IVIG and infliximab (n=3); 11/12 (91.7%) required ICU-level care and 8/12 (75%) died of steroid-refractory ICI-pneumonitis or infectious complications (IVIG alone=3/7, 42.9%; infliximab alone=2/2, 100%; IVIG + infliximab=3/3, 100%). All five patients treated with infliximab (5/5; 100%) died from steroid-refractory ICI-pneumonitis or infectious complications. Mechanical ventilation was required in 53% of patients treated with infliximab alone, 80% of those treated with IVIG + infliximab, and 25.5% of those treated with IVIG alone.ConclusionsSteroid-refractory ICI-pneumonitis constituted 18.5% of referrals for multidisciplinary irAE care. Steroid-refractory ICI-pnuemonitis occurred early in patients’ treatment courses, and most commonly exhibited a DAD radiographic pattern. Patients treated with IVIG alone demonstrated an improvement in both level-of-care and oxygenation requirements and had fewer fatalities (43%) from steroid-refractory ICI-pneumonitis when compared to treatment with infliximab (100% mortality).

IMPORTANCE Although most chemotherapies are dosed on body surface area or weight, body composition (ie, the amount and distribution of muscle and adipose tissues) is thought to be associated with chemotherapy tolerance and adherence.OBJECTIVES To evaluate whether body composition is associated with relative dose intensity (RDI) on anthracycline and taxane-based chemotherapy or hematologic toxic effects and whether lower RDI mediates the association of adiposity with mortality. DESIGN, SETTING, AND PARTICIPANTSAn observational cohort study with prospectively collected electronic medical record data was conducted at Kaiser Permanente Northern California, a multicenter, community oncology setting within an integrated health care delivery system. Participants included 1395 patients with nonmetastatic breast cancer diagnosed between January 1, 2005, and December 31, 2013, and treated with anthracycline and taxane-based chemotherapy. Data analysis was performed between February 25 and September 4, 2019.EXPOSURES Intramuscular, visceral, and subcutaneous adiposity as well as skeletal muscle were evaluated from clinically acquired computed tomographic scans at diagnosis. MAIN OUTCOMES AND MEASURESThe primary outcome was low RDI (<0.85), which is the ratio of delivered to planned chemotherapy dose, derived from infusion records; in addition, hematologic toxic effects were defined based on laboratory test values. To evaluate associations with overall and breast cancer-specific mortality, logistic regression models adjusted for age and body surface area were fit as well as Cox proportional hazards models adjusted for age, race/ethnicity, adiposity, Charlson comorbidity index score, and tumor stage and subtype. The mediation proportion was computed using the difference method. RESULTSThe mean (SD) age at diagnosis of the 1395 women included in the study was 52.8 (10.2) years. Greater visceral (odds ratio [OR], 1.19; 95% CI, 1.02-1.39 per SD) and intramuscular (OR, 1.16; 95% CI, 1.01-1.34 per SD) adiposity were associated with increased odds of RDI less than 0.85. Greater muscle mass was associated with a decreased odds of hematologic toxic effects (OR, 0.84; 95% CI, 0.71-0.98 per SD). Relative dose intensity less than 0.85 was associated with a 30% increased risk of death (hazard ratio, 1.30; 95% CI, 1.02-1.65). Lower RDI partially explained the association of adiposity with breast cancer-specific mortality (mediation proportion, 0.20; 95% CI, 0.05-0.55).CONCLUSIONS AND RELEVANCE Excess adiposity, presenting as larger visceral or intramuscular adiposity, was associated with lower RDI. Lower RDI partially mediated the association of adiposity with worse breast cancer-specific survival. Body composition may help to identify patients likely to experience toxic effects and subsequent dose delays or reductions, which could compromise chemotherapeutic efficacy.

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Chemotherapeutic resistance eventually develops in all patients with metastatic colorectal cancer (mCRC). Gene silencing through promoter demethylation is one potential reversible mechanism of resistance with administration of hypomethylating agents. We evaluated the safety and tolerability of guadecitabine and irinotecan in patients with mCRC previously treated with irinotecan. In this 3+3 dose-escalation study, patients with mCRC previously exposed to irinotecan received guadecitabine days 1 to 5 of a 28-day cycle and irinotecan 125 mg/m days 8 and 15 [dose level (DL) 1, guadecitabine 45 mg/m; DL -1: guadecitabine 30 mg/m; DL -1G: guadecitabine 30 mg/m with growth factor support (GFS); DL 1G: guadecitabine 45 mg/m with GFS]. Twenty-two patients were treated across four DLs. Dose-limiting toxicities were neutropenic fever (DL 1 and -1G), biliary drain infection (DL -1), colonic obstruction (DL -1), and severe dehydration (DL 1G). Most common toxicities were neutropenia (82% any grade, 77% Grade 3/4), neutropenic fever (23%), leukopenia (73% any grade, 50% Grade 3/4), and injection site reactions (64% total, 0% Grade 3/4). Patients received a median of 4.5 cycles of treatment; 12/17 evaluable patients had stable disease as best response, with one having initial disease progression but subsequently durable partial response. Circulating tumor DNA showed decrease in global demethylation by LINE-1 after treatment. We report the first study of chemo-priming with epigenetic therapy in gastrointestinal cancers. Guadecitabine 45 mg/m and irinotecan 125 mg/m with GFS was safe and tolerable in patients with mCRC, with early indication of benefit. These data have provided the basis for an ongoing phase II randomized, multicenter trial.

The use of neoadjuvant chemotherapy or radiation for borderline resectable pancreatic adenocarcinoma (BL‐PDAC) is increasing. However, the impact of neoadjuvant chemotherapy and radiation therapy on the outcome of BL‐PDAC remains to be elucidated. We performed a retrospective analysis of 93 consecutive patients who were diagnosed with BL‐PDAC and primarily followed at Johns Hopkins Hospital between February 2007 and December 2012. Among 93 patients, 62% received upfront neoadjuvant chemotherapy followed by chemoradiation, whereas 20% received neoadjuvant chemoradiation alone and 15% neoadjuvant chemotherapy alone. Resectability following all neoadjuvant therapy was 44%. Patients who underwent resection with a curative intent had a median overall survival (mOS) of 25.8 months, whereas those who did not undergo surgery had a mOS of 11.9 months. However, resectability and overall survival were not significantly different between the three types of neoadjuvant therapy. Nevertheless, 22% (95% CI, 0.13–0.36) of the 58 patients who received upfront chemotherapy followed by chemoradiation remained alive for a minimum of 48 months compared to none of the 19 patients who received upfront chemoradiation. Among patients who underwent curative surgical resection, 32% (95% CI, 0.19–0.55) of those who received upfront chemotherapy remained disease free at least 48 months following surgical resection, whereas none of the eight patients who received upfront chemoradiation remained disease free beyond 24 months following surgical resection. Neoadjuvant therapy with upfront chemotherapy may result in long‐term survival in a subpopulation of patients with BL‐PDAC.