Immune checkpoint inhibitors for POLE or POLD1 proofreading-deficient metastatic colorectal cancer

BACKGROUND

POLE and POLD1 proofreading deficiency (POLE/D1pd) define a rare subtype of ultramutated metastatic colorectal cancer (mCRC; over 100 mut/Mb). Disease-specific data about the activity and efficacy of immune checkpoint inhibitors (ICIs) in POLE/D1pd mCRC are lacking and it is unknown whether outcomes may be different from mismatch repair-deficient (dMMR)/microsatellite instability-high (MSI-H) mCRCs treated with ICIs.

PATIENTS AND METHODS

In this global study, we collected 27 patients with mCRC harboring POLE/D1 mutations leading to proofreading deficiency and treated with anti-programmed cell death-ligand 1 alone +/- anti-cytotoxic T-lymphocyte antigen-4 agents. We collected clinicopathological and genomic characteristics, response, and survival outcomes after ICIs of POLE/D1pd mCRC and compared them with a cohort of 610 dMMR/MSI-H mCRC patients treated with ICIs. Further genomic analyses were carried out in an independent cohort of 7241 CRCs to define POLE and POLD1pd molecular profiles and mutational signatures.

RESULTS

POLE/D1pd was associated with younger age, male sex, fewer RAS/BRAF driver mutations, and predominance of right-sided colon cancers. Patients with POLE/D1pd mCRC showed a significantly higher overall response rate (ORR) compared to dMMR/MSI-H mCRC (89% versus 54%; P = 0.01). After a median follow-up of 24.9 months (interquartile range: 11.3-43.0 months), patients with POLE/D1pd showed a significantly superior progression-free survival (PFS) compared to dMMR/MSI-H mCRC [hazard ratio (HR) = 0.24, 95% confidence interval (CI) 0.08-0.74, P = 0.01] and superior overall survival (OS) (HR = 0.38, 95% CI 0.12-1.18, P = 0.09). In multivariable analyses including the type of DNA repair defect, POLE/D1pd was associated with significantly improved PFS (HR = 0.17, 95% CI 0.04-0.69, P = 0.013) and OS (HR = 0.24, 95% CI 0.06-0.98, P = 0.047). Molecular profiling showed that POLE/D1pd tumors have higher tumor mutational burden (TMB). Responses were observed in both subtypes and were associated with the intensity of POLE/D1pd signature.

CONCLUSIONS

Patients with POLE/D1pd mCRC showed more favorable outcomes compared to dMMR/MSI-H mCRC to treatment with ICIs in terms of tumor response and survival.

Development of a composite drought indicator for operational drought monitoring in the MENA region

This paper presents the composite drought indicator (CDI) that Jordanian, Lebanese, Moroccan, and Tunisian government agencies now produce monthly to support operational drought management decision making, and it describes their iterative co-development processes. The CDI is primarily intended to monitor agricultural and ecological drought on a seasonal time scale. It uses remote sensing and modelled data inputs, and it reflects anomalies in precipitation, vegetation, soil moisture, and evapotranspiration. Following quantitative and qualitative validation assessments, engagements with policymakers, and consideration of agencies' technical and institutional capabilities and constraints, we made changes to CDI input data, modelling procedures, and integration to tailor the system for each national context. We summarize validation results, drought modelling challenges and how we overcame them through CDI improvements, and we describe the monthly CDI production process and outputs. Finally, we synthesize procedural and technical aspects of CDI development and reflect on the constraints we faced as well as trade-offs made to optimize the CDI for operational monitoring to support policy decision-making-including aspects of salience, credibility, and legitimacy-within each national context.

Impact of KRASG12 mutations on survival with trifluridine/tipiracil plus bevacizumab in patients with refractory metastatic colorectal cancer: post hoc analysis of the phase III SUNLIGHT trial

BACKGROUND

In metastatic colorectal cancer (mCRC), KRAS mutations are often associated with poorer survival; however, the prognostic impact of specific point mutations is unclear. In the phase III SUNLIGHT trial, trifluridine/tipiracil (FTD/TPI) plus bevacizumab significantly improved overall survival (OS) versus FTD/TPI alone. We assessed the impact of KRASG12 mutational status on OS in SUNLIGHT.

PATIENTS AND METHODS

In the global, open-label, randomized, phase III SUNLIGHT trial, adults with mCRC who had received no more than two prior chemotherapy regimens were randomized 1 : 1 to receive FTD/TPI alone or FTD/TPI plus bevacizumab. In this post hoc analysis, OS was assessed according to the presence or absence of a KRASG12 mutation in the overall population and in patients with RAS-mutated tumors.

RESULTS

Overall, 450 patients were analyzed, including 302 patients in the RAS mutation subgroup (214 with a KRASG12 mutation and 88 with a non-KRASG12RAS mutation). In the overall population, similar OS outcomes were observed in patients with and without a KRASG12 mutation [median 8.3 and 9.2 months, respectively; hazard ratio (HR) 1.09, 95% confidence interval (CI) 0.87-1.4]. Similar OS outcomes were also observed in the subgroup analysis of patients with a KRASG12 mutation versus those with a non-KRASG12RAS mutation (HR 1.03, 95% CI 0.76-1.4). FTD/TPI plus bevacizumab improved OS compared with FTD/TPI alone irrespective of KRASG12 mutational status. Among patients with a KRASG12 mutation, the median OS was 9.4 months with FTD/TPI plus bevacizumab versus 7.2 months with FTD/TPI alone (HR 0.67, 95% CI 0.48-0.93), and in patients without a KRASG12 mutation, the median OS was 11.3 versus 7.1 months, respectively (HR 0.59, 95% CI 0.43-0.81).

CONCLUSIONS

The presence of a KRASG12 mutation had no detrimental effect on OS among patients treated in SUNLIGHT. The benefit of FTD/TPI plus bevacizumab over FTD/TPI alone was confirmed independently of KRASG12 status.

A phase II study of retifanlimab (INCMGA00012) in patients with squamous carcinoma of the anal canal who have progressed following platinum-based chemotherapy (POD1UM-202)

Background

Locally advanced or metastatic squamous carcinoma of the anal canal (SCAC) has poor prognosis following platinum-based chemotherapy. Retifanlimab (INCMGA00012), a humanized monoclonal antibody targeting programmed death protein-1 (PD-1), demonstrated clinical activity across a range of solid tumors in clinical trials. We present results from POD1UM-202 (NCT03597295), an open-label, single-arm, multicenter, phase II study evaluating retifanlimab in patients with previously treated advanced or metastatic SCAC.

Patients and methods

Patients ≥18 years of age had measurable disease and had progressed following, or were ineligible for, platinum-based therapy. Retifanlimab 500 mg was administered intravenously every 4 weeks. The primary endpoint was overall response rate (ORR) by independent central review. Secondary endpoints were duration of response (DOR), disease control rate (DCR), progression-free survival (PFS), overall survival (OS), and safety.

Results

Overall, 94 patients were enrolled. At a median follow-up of 7.1 months (range, 0.9-19.4 months), ORR was 13.8% [95% confidence interval (CI) 7.6% to 22.5%], with one complete response (1.1%) and 12 partial responses (12.8%). Responses were observed regardless of human immunodeficiency virus or human papillomavirus status, programmed death ligand 1 (PD-L1) expression, or liver metastases. Stable disease was observed in 33 patients (35.1%) for a DCR of 48.9% (95% CI 38.5% to 59.5%). Median DOR was 9.5 months (range, 5.6 months-not estimable). Median (95% CI) PFS and OS were 2.3 (1.9-3.6) and 10.1 (7.9-not estimable) months, respectively. Retifanlimab safety in this population was consistent with previous experience for the PD-(L)1 inhibitor class.

Conclusions

Retifanlimab demonstrated clinically meaningful and durable antitumor activity, and an acceptable safety profile in patients with previously treated locally advanced or metastatic SCAC who have progressed on or are intolerant to platinum-based chemotherapy.

•

Retifanlimab (PD-1 inhibitor) monotherapy demonstrated encouraging results in patients with platinum-refractory SCAC.

•

Clinically meaningful antitumor activity was reported with ORR of 13.8% and stable disease in 35.1%, for a DCR of 48.9%.

•

Observed responses in advanced SCAC were durable (median 9.5 months).

•

Acceptable safety profile consistent with that reported for the PD-(L)1 inhibitor class.

•

Promising results warrant further investigation of retifanlimab in advanced SCAC as well as earlier stages of disease.

Longest Survival of Expectantly Managed Twin Gestation Complicated by Previable Preterm Premature Rupture of Membranes at 13 Weeks' Gestation

Previable preterm premature rupture of membranes (PV-PPROM) is defined as rupture of membranes prior to 24 weeks and is a rare phenomenon with an estimated prevalence of 0.5% of all pregnancies. Given that this phenomenon is even more rare in patients with dichorionic diamniotic (DCDA) twin pregnancies, there is no clear consensus in the literature on outcomes and management of DCDA PV-PPROM due to the scarcity of reports. We report a case of a rare successful prolongation of first trimester DCDA PV-PPROM pregnancy with rupture of the amniotic sac of one twin with survival of both twins without major complications. A 20-year-old female gravida 1 para 0 at about 13 weeks and three days presented with vaginal watery discharge mixed with vaginal bleeding. Abdominal ultrasound revealed a live twin dichorionic diamniotic (DCDA) spontaneous intrauterine gestation and a significantly low amniotic fluid volume involving fetus A. At 23 weeks gestational age, she experienced increased leaking of clear fluid, and she was admitted to the hospital for continuous monitoring with daily non-stress tests (NST), and ultrasounds every four weeks, and received antibiotics, betamethasone, and magnesium. Preterm labor occurred at 30w1d, and a primary low transverse cesarean section was performed on the 114th day after PPROM. Though, twin A required prolonged hospitalization both twins recovered and progressed well without complications. To the best of our knowledge, this is the longest case of successful expectant management of both twins with PV-PPROM yet reported.

Successful Use of Myosure in the Management of Cesarean Scar Ectopic Pregnancy

Cesarean scar pregnancy (CSP) is a very serious complication of a prior cesarean delivery. The major risks associated with CSP are uncontrolled hemorrhage and uterine rupture, potentially leading to future infertility. Management of CSP remains a major obstetric challenge without a well-defined therapeutic procedure. Dilation & curettage is a commonly used procedure for the treatment of CSP. However, it can be ineffective and often leads to definite infertility. Therefore, we present a case of the successful use of an alternative procedure, Myosure® hysteroscopy, in the treatment of CSP. We herein report the case of a 32-year-old G5P3013 woman who presented with vaginal bleeding and past history of three cesarean sections. She was found to have a CSP with fetal pole and cardiac activity at 6 weeks 2 days. The patient was initially treated with a systemic methotrexate injection, but there was persistence of cardiac activity. A second course of methotrexate was administered into the gestational sac, which systemically led to successful fetal cardiac arrest and downtrend of beta-human chorionic gonadotropin (HCG) level. A dilation & curettage procedure was not successful in removing products of conception. A Myosure hysteroscopy procedure, however, was successful in removing products of conception. The patient was discharged after a negative ultrasound and beta-HCG level. In our review of the literature, we found that there is no general consensus on the management of cesarean scar ectopic pregnancies. To date, there is no literature cited about the use of Myosure for cesarean scar ectopic pregnancies. However, our case suggests that Myosure can be effective for CSP and this warrants a larger-scale controlled study to better evaluate this as a treatment for this condition.

Management of BRAF-mutant metastatic colorectal cancer: a review of treatment options and evidence-based guidelines

BACKGROUND

Colorectal cancer (CRC) is still a leading cause of cancer-related deaths in the United States and worldwide, despite recent improvements in cancer management. CRC, like many malignancies, is a heterogeneous disease, with subtypes characterized by genetic alterations. One common mutation in CRC is in the BRAF gene (most commonly V600E substitution). This occurs in ∼10% of patients with metastatic CRC (mCRC) and is a marker of poor prognosis.

DESIGN

Herein, we review the clinical and translational literature on the role of the BRAF V600E mutation in the pathogenesis of mCRC, its mechanisms as a prognostic marker, and its potential utility as a predictive marker of treatment response. We then summarize the current evidence-based recommendations for management of BRAF V600E-mutated mCRC, with a focus on recent clinical research advances in this setting.

RESULTS

The current standard therapies for first-line treatment of BRAF-mutated mCRC are chemotherapy with bevacizumab as well as 5-fluorouracil, leucovorin, oxaliplatin, and irinotecan (FOLFOXIRI) plus bevacizumab in patients with a good performance status. Combination strategies involving mitogen-activated protein kinase (MAPK) pathway blockade have shown promising results for the treatment of patients with BRAF V600E-mutated mCRC. The Binimetinib, Encorafenib, And Cetuximab cOmbiNed to treat BRAF-mutant ColoRectal Cancer (BEACON CRC) study represents the largest study in this population to date and has given strong clinical evidence to support BRAF and epidermal growth factor receptor inhibition with the combination of encorafenib plus cetuximab.

CONCLUSIONS

The treatment of BRAF-mutated mCRC has evolved rapidly over the last several years. Recently, combination strategies involving MAPK pathway blockade have shown promising results in BRAF V600E-mutated mCRC, and other potential targets continue to be explored. In addition, a greater understanding of the role of BRAF V600E mutation in the pathogenesis of CRC should also continue to fuel advances in the management of patients with mCRC harboring this genetic aberration.

Tumor mutational burden is predictive of response to immune checkpoint inhibitors in MSI-high metastatic colorectal cancer

BACKGROUND

Microsatellite instability (MSI) is a biomarker for response to immune checkpoint inhibitors (ICPIs). PD-1 inhibitors in metastatic colorectal carcinoma (mCRC) with MSI-high (MSI-H) have demonstrated a high disease control rate and favorable progression-free survival (PFS); however, reported response rates to pembrolizumab and nivolumab are variable and often <50%, suggesting that additional predictive biomarkers are needed.

METHODS

Clinicopathologic data were collected from patients with MSI-H mCRC confirmed by hybrid capture-based next-generation sequencing (NGS) treated with PD-1/L1 inhibitors at five institutes. Tumor mutational burden (TMB) was determined on 0.8-1.1 Mb of sequenced DNA and reported as mutations/Mb. Potential biomarkers of response and time to progression were analyzed by univariate and multivariate analyses. Once TMB was confirmed as a predictive biomarker, a larger dataset of 18 140 unique CRC patients was analyzed to define the relevance of the identified TMB cut-point.

RESULTS

A total of 22 patients were treated with PD-1/L1 inhibitors including 19 with pembrolizumab monotherapy. Among tested variables, TMB showed the strongest association with objective response (OR; P < 0.001) and PFS, by univariate (P < 0.001) and multivariate analysis (P < 0.01). Using log-rank statistics, the optimal predictive cut-point for TMB was estimated between 37 and 41 mutations/Mb. All 13 TMBhigh cases responded, while 6/9 TMBlow cases had progressive disease. The median PFS for TMBhigh has not been reached (median follow-up >18 months) while the median PFS for TMBlow was 2 months. A TMB of 37.4 mutations/Mb in a large MSI-H mCRC population (821/18, 140 cases; 4.5%) evaluated by NGS corresponded to the 35th percentile cut-point.

CONCLUSIONS

TMB appears to be an important independent biomarker within MSI-H mCRC to stratify patients for likelihood of response to ICPIs. If validated in prospective studies, TMB may play an important role in guiding the sequencing and/or combinations of ICPIs in MSI-H mCRC.

Adverse events associated with anti-EGFR therapies for the treatment of metastatic colorectal cancer

The epidermal growth factor receptor (EGFR), a member of the ErbB family of receptor tyrosine kinases, plays an important role in the control of cell growth and differentiation. Disruption of its signaling leads to neoplastic cell proliferation, migration, stromal invasion, resistance to apoptosis, and angiogenesis.

EGFR is overexpressed in a variety of solid tumors, including colorectal cancer (CRC), and its overexpression is associated with poorer prognosis. One class of agents that is currently used to target EGFR in the treatment of metastatic CRC (mCRC) is the monoclonal antibodies. While the monoclonal antibody EGFR inhibitors lack many of the severe side effects commonly observed with cytotoxic chemotherapy, they are associated with a set of unique dermatological toxicities. This paper reviews the safety profile of the anti-EGFR monoclonal antibodies cetuximab and panitumumab in the treatment of mCRC.

Efficacy of the monoclonal antibody EGFR inhibitors for the treatment of metastatic colorectal cancer

Two anti-epidermal growth factor receptor (EGFR) monoclonal antibodies (MoAbs) have been approved in Canada for the treatment of metastatic colorectal cancer (mCRC) – cetuximab, a mouse-human chimeric MoAb, and panitumumab, a fully human MoAb. This paper reviews the efficacy of the anti-EGFR monoclonal antibodies cetuximab and panitumumab – both as monotherapy and in combination with cytotoxic chemotherapy – in the treatment of mCRC. Both cetuximab and panitumumab have demonstrated clinical efficacy in monotherapy in patients with mCRC, an advantage that has recently been found to be limited largely to those with wild-type KRAS tumors. Advantages of using these agents in monotherapy include reduced cost and toxicity. While the addition of cetuximab to irinotecan has shown superior progression-free survival and response compared with cetuximab monotherapy, there is currently no evidence for a benefit of panitumumab in combination with irinotecan.

A phase II trial of high-dose cetuximab (cmab) plus irinotecan in patients (pts) with KRAS wild-type (WT) metastatic colorectal cancer (MCRC) who progressed on standard-dose cmab plus irinotecan

598

Background: Prior clinical data suggest a dose-related response to cmab when combined with irinotecan in pts with KRAS WT tumors who do not develop grade 2 and above rash with standard cmab dosing. However, the investigation of higher doses of cmab in the setting of acquired or innate resistance to standard dose cmab has not been previously investigated. We conducted a phase II clinical trial of high-dose cmab plus irinotecan in KRAS WT pts with standard-dose cmab plus irinotecan – refractory disease to address this question.

Methods: Pts with KRAS WT MCRC progressing on standard dose of cmab with irinotecan were eligible for study. Pts should have received a minimum of 6 weeks of prior standard dose cmab plus irinotecan and progressed within 4 weeks from the last dose. Cmab was administered at 500 mg/m2/week and irinotecan was administered at the same dose/schedule on which the patient previously progressed. 12-week PFS rate was the primary endpoint.

Results: 8 pts were treated on study: median age 68 yrs (45-85), 5 pts were males, ECOG performance status was 1 in all 8 pts. Grade ≥ 3 toxicities consisted of hypomagnesaemia (4 pts), anemia (1 pt), leucopenia (1 pt), fatigue (1 pt), and diarrhea (1 pt). 6 pts achieved stable disease (with regression in target lesions noted in 3 pts). 12 week PFS rate is 5/8 and 18 week PFS is 4/8. 3 pts remain on study at 4.5, 5, and 8 months from enrollment.

Conclusions: High-dose cmab/irinotecan is well tolerated except for hypomagnesemia. Encouraging prolonged disease stabilizations warrant further investigation of this approach in pts in KRAS WT population. Accrual is ongoing.

[Table: see text]

Renal atrophy secondary to chemoradiation treatment of abdominal malignancies

e15532

Background: Information on renal atrophy following abdominal chemoradiation (CRT) is limited. Methods: Patients who received concurrent CRT to the abdomen between 2002 and 2008 were identified for this study to evaluate change in renal size (RS) and function following CRT. Imaging and biochemical data were obtained prior to radiation (RT) and after RT in 6 month intervals. RS was defined by craniocaudal measurement on CT images. Renal function was assessed by serum creatinine and creatinine clearance (CrCl) using the Cockcroft-Gault formula. The primarily irradiated kidney (PK) was defined as the kidney that received the greater mean kidney dose. Results: Median patient age was 64 years (range 31–87), 51.5% of 130 patients were male. Primary disease sites were pancreas (61.5%), periampullary (16.1%), stomach (10.8%), gastroesophageal junction (10%), and retroperitoneum (1.5%). Median follow up was 9.4 months (range 0–55.4 mos). Median radiation dose was 50.4Gy (range 12.6- 55.8Gy). Mean dose to the PK was 18.6 Gy. Compensatory hypertrophy of the non-PK was not seen. Age, gender, hypertension, diabetes, smoking, pre-RT CrCl, and pre-RT RS were not associated with renal atrophy at 12 months post RT. Percent volumes of the PK receiving ≥10Gy (V10), 15Gy (V15), and 20Gy (V20) were significantly associated with renal atrophy at 12 months post RT (p=0.0030, 0.0041, and 0.0046 respectively). Conclusions: Significant detriments in PK size and renal function were seen following abdominal CRT. V10, V15, and V20 were associated with renal atrophy at 12 months post RT. These observations can assist with renal dose constraints in CRT treatment planning for patients at increased risk for renal complications.

[Table: see text]

No significant financial relationships to disclose.

Primary adenocarcinoma of the anus: a 22-year SEER population database analysis

e15072

Background: Most anal canal cancers consist of squamous cell carcinoma (SCCA). Adenocarcinoma (AdenoCa) is rare and accounts for approximately 10% of anal cancers. A search of the SEER database (1973 to 2005) was carried out to evaluate the pattern of radiation (RT) and surgical treatment. Impact of the treatment on overall survival (OS) was evaluated. Methods: The search of the SEER database revealed 1,008 pts who had pathologically confirmed anal cancers with either SCCA or AdenoCa. All pts had single diagnosis of anal cancer with localized disease without nodal involvement. Excluded were pts with unknown use of surgery or radiation. Kaplan-Meier estimates and Cox-Mantel model were used to calculate and compare survival rates. Results: Median age of all pts was 57 years (range 29 to 99). For the SCCA group, median age was 57 years (range 29 to 99), which was younger than the AdenoCa group with median age of 74 years (range 37 to 92). Among the 1,008 pts, 954 had SCCA (94.6%), and 54 had AdenoCa (5.4%). Within the SCCA group, 14 (1.5%) had abdominoperineal resection (APR) in combination with external beam RT, and 795 (83.3%) had RT only with non-APR local surgical treatment inclusive of excision. Remaining 145 SCCA pts (15.2%) had non-APR local surgical treatment only without RT or had no treatment. Within the AdenoCa group, 10 (18.5%) had APR in combination with external beam RT, and 21 (38.9%) had RT only with non-APR local surgical treatment inclusive of excision. Remaining 23 AdenoCa pts (42.6%) had non-APR local surgical treatment only without RT. None of the adenoCa pt had no treatment. OS at 10 years was superior for pts with SCCA vs. AdenoCa (64.9% vs. 25.8%, p<0.05). Among the SCCA subset, there was no signficant difference in the 10-yr OS between the APR versus the RT pts (71% vs. 65%, p=0.78). On the other hand, among the AdenoCa subset, pts who had APR had better 10-yr OS than RT pts (53.8% vs. 0%, p=0.03) Conclusions: For localized anal SCCA, RT yielded equivalent overall survival as compared to APR. On the other hand, pts with localized anal adenoCa appeared to do worse when APR was omitted. RT only without APR might not be sufficient treatment in these patients. This database lacks information on use of chemotherapy and local disease control. Omission of APR in pts with anal canal adenoCa should be cautiously weighed.

No significant financial relationships to disclose.