Quantitative proteomic analysis of HER2 protein expression in PDAC tumors

Metastatic pancreatic adenocarcinoma (PDAC) is the third leading cause of cancer-related death in the United States, with a 5-year survival rate of only 11%, necessitating identification of novel treatment paradigms. Tumor tissue specimens from patients with PDAC, breast cancer, and other solid tumor malignancies were collected and tumor cells were enriched using laser microdissection (LMD). Reverse phase protein array (RPPA) analysis was performed on enriched tumor cell lysates to quantify a 32-protein/phosphoprotein biomarker panel comprising known anticancer drug targets and/or cancer-related total and phosphorylated proteins, including HER2Total, HER2Y1248, and HER3Y1289. RPPA analysis revealed significant levels of HER2Total in PDAC patients at abundances comparable to HER2-positive (IHC 3+) and HER2-low (IHC 1+ /2+ , FISH-) breast cancer tissues, for which HER2 screening is routinely performed. These data support a critical unmet need for routine clinical evaluation of HER2 expression in PDAC patients and examination of the utility of HER2-directed antibody-drug conjugates in these patients.

Pembrolizumab in Patients With Tumors With High Tumor Mutational Burden: Results From the Targeted Agent and Profiling Utilization Registry Study

PURPOSE

The Targeted Agent and Profiling Utilization Registry (TAPUR) Study is a pragmatic basket trial evaluating antitumor activity of approved targeted agents in patients with advanced cancers harboring potentially actionable genomic alterations. Data from cohorts of patients with high tumor mutational burden (HTMB, defined as ≥9 mutations per megabase) with advanced colorectal cancer (CRC) and other advanced cancers treated with pembrolizumab are reported.

METHODS

Eligible patients were 18 years and older with measurable tumors and a lack of standard treatment options, an Eastern Cooperative Oncology Group performance status of 0-1, and adequate organ function. The primary end point was disease control (DC), defined as complete or partial response or stable disease (SD) of at least 16-weeks duration. For the CRC cohort, Simon's two-stage design with a null DC rate of 15% versus 35% (power = 0.85; α = .10) was used. Low accruing histology-specific cohorts were collapsed into one histology-pooled (HP) cohort. For the HP cohort, the null hypothesis of a DC rate of 15% was rejected if the lower limit of a one-sided 90% CI was >15%. Secondary end points included objective response (OR), safety, progression-free survival, overall survival, duration of response, and duration of SD.

RESULTS

Seventy-seven patients with HTMB with CRC (n = 28) or advanced cancers (n = 49) were treated with pembrolizumab. For the CRC cohort, the DC rate was 31% (P = .04) and the OR rate was 11%. For the HP cohort, the DC rate was 45% (one-sided 90% CI, 35 to 100) and the OR rate was 26%. The null hypothesis of a 15% DC rate was rejected for both cohorts. Twelve of 77 patients experienced treatment-related grade 3 adverse events (AEs) or serious AEs, including two deaths.

CONCLUSION

Pembrolizumab demonstrated antitumor activity in pretreated patients with advanced cancers and HTMB.

Cobimetinib Plus Vemurafenib in Patients With Solid Tumors With BRAF Mutations: Results From the Targeted Agent and Profiling Utilization Registry Study

PURPOSE

The Targeted Agent and Profiling Utilization Registry Study is a phase II basket study evaluating antitumor activity of commercially available targeted agents in patients with advanced cancers with genomic alterations known to be drug targets. The results in a cohort of patients with solid tumors with BRAF mutations treated with cobimetinib plus vemurafenib are reported.

METHODS

Eligible patients had measurable disease (RECIST v.1.1), Eastern Cooperative Oncology Group performance status 0-2, adequate organ function, and no standard treatment options. The primary end point was disease control (DC), defined as complete response (CR) or partial response (PR) or stable disease of at least 16-weeks duration (SD16+). Low-accruing histology-specific cohorts with BRAF mutations treated with cobimetinib plus vemurafenib were collapsed into a single histology-pooled cohort for this analysis. The results were evaluated on the basis of a one-sided exact binomial test with a null DC rate of 15% versus 35% (power, .82; α, .10). The secondary end points were objective response (OR), progression-free survival, overall survival, duration of response, duration of stable disease, and safety.

RESULTS

Thirty-one patients with solid tumors with BRAF mutations were enrolled. Twenty-eight patients were evaluable for efficacy. Patients had tumors with BRAF V600E (n = 26), K601E (n = 2), or other (n = 3) mutations. Two patients with CR (breast and ovarian cancers; V600E), 14 with PR (13 V600E, one N581I), and three with SD16+ (two V600E, one T599_V600insT) were observed with a DC rate of 68% (P < .0001; one-sided 90% CI, 54 to 100) and an OR rate of 57% (95% CI, 37 to 76). Nineteen patients experienced ≥one drug-related grade 3-5 adverse event or serious adverse event including one death attributed to treatment-related kidney injury.

CONCLUSION

Cobimetinib plus vemurafenib showed antitumor activity in patients with advanced solid tumors with BRAF V600E mutations; additional study is warranted to confirm the antitumor activity in tumors with non-V600E BRAF mutations.

Integration of Multi-omic Data in a Molecular Tumor Board Reveals EGFR-Associated ALK-Inhibitor Resistance in a Patient With Inflammatory Myofibroblastic Cancer

Inflammatory myofibroblastic tumors (IMTs) are intermediate-grade mesenchymal neoplasms commonly characterized by chromosomal rearrangements causing constitutive activation of anaplastic lymphoma kinase (ALK) and/or ALK mutations causing reduced sensitivity to ALK tyrosine kinase inhibitors (TKI). We present a patient with an IMT who initially responded to first-line alectinib, but who later suffered disease relapse and presently survives with moderate residual disease after receiving second-line lorlatinib. Biopsy specimens were analyzed using next generation sequencing (DNA-seq and RNA-seq) and reverse phase protein microarray (RPPA) as part of an institutional Molecular Tumor Board (MTB) study. An EML4-ALK rearrangement and EGFR activation (pEGFRY1068) were present in both the primary and recurrent tumors, while a secondary ALK I1171N mutation was exclusive to the latter. EGFR signaling in the background of a secondary ALK mutation is correlated with reduced ALK TKI sensitivity in vitro, implicating an important mechanism of drug resistance development in this patient. The RPPA results also critically demonstrate that ALK signaling (ALKY1604) was not activated in the recurrent tumor, thereby indicating that standard-of-care use of third- or fourth-line ALK TKI would not likely be efficacious or durable. These results underscore the importance of real-time clinical integration of functional protein drug target activation data with NGS in the MTB setting for improving selection of patient-tailored therapy.

Cobimetinib Plus Vemurafenib in Patients With Colorectal Cancer With BRAF Mutations: Results From the Targeted Agent and Profiling Utilization Registry (TAPUR) Study

PURPOSE

TAPUR is a phase II basket trial evaluating the antitumor activity of commercially available targeted agents in patients with advanced cancer and genomic alterations known to be drug targets. The results of a cohort of patients with colorectal cancer (CRC) with BRAF mutations treated with cobimetinib (C) plus vemurafenib (V) are reported.

METHODS

Eligible patients had advanced CRC, no standard treatment options, measurable disease (RECIST), Eastern Cooperative Oncology Group performance status 0-2, adequate organ function, tumors with BRAF V600E/D/K/R mutations, and no MAP2K1/2, MEK1/2, or NRAS mutations. C was taken 60 mg orally once daily for 21 days followed by seven days off, and V was taken 960 mg orally twice daily. Simon's two-stage design was used with a primary study end point of objective response or stable disease of at least 16 weeks duration. Secondary end points were progression-free survival, overall survival, and safety.

RESULTS

Thirty patients were enrolled from August 2016 to August 2018; all had CRC with a BRAF V600E mutation except one patient with a BRAF K601E mutation. Three patients were not evaluable for efficacy. Eight patients with partial responses and six patients with stable disease of at least 16 weeks duration were observed for disease control and objective response rates of 52% (95% CI, 35 to 65) and 30% (95% CI, 14 to 50), respectively. The null hypothesis of 15% disease control rate was rejected ( P < .0001). Thirteen patients had at least one grade 3 adverse event or serious adverse event at least possibly related to C + V: anemia, decreased lymphocytes, dyspnea, diarrhea, elevated liver enzymes, fatigue, hypercalcemia, hypophosphatemia, rash, photosensitivity, and upper gastrointestinal hemorrhage.

CONCLUSION

The combination of C + V has antitumor activity in heavily pretreated patients with CRC with BRAF mutations.

Remote Home Monitoring of Patients With Cancer During the COVID Pandemic: A Pilot Study

PURPOSE

The COVID-19 pandemic has posed significant challenges in the care of patients with cancer, including how to manage outpatients who are COVID-positive but do not require hospitalization. We explored the use of a remote patient monitoring (RPM) program to care for such outpatients.

METHODS

Consecutive patients who were tested for COVID-19 because of symptom onset but were clinically stable were offered enrollment into a pilot RPM program. Patients were provided equipment for vital sign measurements and a computer tablet to enter results three times per day. The results were monitored centrally by clinical staff. The goal was to closely monitor patients and escalate care as warranted.

RESULTS

Between March and June of 2020, 29 patients were approached and 26 were enrolled. The mean age was 57 years old (range, 30-88), 14 were women, and patients remained in the program for an average of 16 days (range, 2-63). Twenty-four patients (83%) were on active anticancer therapy. During that time period, only one patient was admitted to the hospital for worsening respiratory symptoms. The percentage of days during which at least one set of data and all three sets of data were entered was 97.2% and 65.7%, respectively. There was no association between the demographic factors of age, sex, or the reason for being monitored with the level of engagement (P > .05).

CONCLUSION

In this pilot study, patients with cancer were readily enrolled in a remote home monitoring program. Monitoring was feasible, and there was a high rate of engagement with the program. The role of RPM should be further tested as the COVID pandemic continues.

Pembrolizumab in Patients With Metastatic Breast Cancer With High Tumor Mutational Burden: Results From the Targeted Agent and Profiling Utilization Registry (TAPUR) Study

PURPOSE

The TAPUR Study is a phase II basket trial that aims to identify signals of antitumor activity of commercially available targeted agents in patients with advanced cancers harboring genomic alterations known to be drug targets. Results in a cohort of patients with metastatic breast cancer (mBC) with high tumor mutational burden (HTMB) treated with pembrolizumab are reported.

METHODS

Patients with advanced mBC received standard doses of either 2 mg/kg or 200 mg infusions of pembrolizumab every 3 weeks. Simon's two-stage design was used with a primary study end point of disease control (DC) defined as objective response or stable disease of at least 16 weeks duration. If two or more patients in stage I achieved DC, the cohort would enroll 18 additional patients in stage II. Secondary end points include progression-free survival (PFS), overall survival, and safety.

RESULTS

Twenty-eight patients were enrolled from October 2016 to July 2018. All patients' tumors had HTMB ranging from 9 to 37 mutations/megabase. DC and objective response were noted in 37% (95% CI, 21 to 50) and 21% of patients (95% CI, 8 to 41), respectively. Median PFS was 10.6 weeks (95% CI, 7.7 to 21.1); median overall survival was 30.6 weeks (95% CI, 18.3 to 103.3). No relationship was observed between PFS and tumor mutational burden. Five patients experienced ≥ 1 serious adverse event or grade 3 adverse event at least possibly related to pembrolizumab consistent with the product label.

CONCLUSION

Pembrolizumab monotherapy has antitumor activity in heavily pretreated patients with mBC characterized by HTMB. Our findings support the recent US Food and Drug Administration approval of pembrolizumab for treatment of patients with unresectable or metastatic solid tumors with HTMB without alternative treatment options.

American Society of Clinical Oncology Road to Recovery Report: Learning From the COVID-19 Experience to Improve Clinical Research and Cancer Care

This report presents the American Society of Clinical Oncology's (ASCO's) evaluation of the adaptations in care delivery, research operations, and regulatory oversight made in response to the coronavirus pandemic and presents recommendations for moving forward as the pandemic recedes. ASCO organized its recommendations for clinical research around five goals to ensure lessons learned from the COVID-19 experience are used to craft a more equitable, accessible, and efficient clinical research system that protects patient safety, ensures scientific integrity, and maintains data quality. The specific goals are: (1) ensure that clinical research is accessible, affordable, and equitable; (2) design more pragmatic and efficient clinical trials; (3) minimize administrative and regulatory burdens on research sites; (4) recruit, retain, and support a well-trained clinical research workforce; and (5) promote appropriate oversight and review of clinical trial conduct and results. Similarly, ASCO also organized its recommendations regarding cancer care delivery around five goals: (1) promote and protect equitable access to high-quality cancer care; (2) support safe delivery of high-quality cancer care; (3) advance policies to ensure oncology providers have sufficient resources to provide high-quality patient care; (4) recognize and address threats to clinician, provider, and patient well-being; and (5) improve patient access to high-quality cancer care via telemedicine. ASCO will work at all levels to advance the recommendations made in this report.

Palbociclib in Patients With Non–Small-Cell Lung Cancer With CDKN2A Alterations: Results From the Targeted Agent and Profiling Utilization Registry Study

PURPOSE

The Targeted Agent and Profiling Utilization Registry (TAPUR) Study is a phase II pragmatic basket trial evaluating antitumor activity of commercially available targeted agents in patients with advanced cancer with genomic alterations known to be drug targets. Results in a cohort of patients with non–small-cell lung cancer (NSCLC) with CDKN2A alterations treated with palbociclib are reported.

METHODS

Eligible patients were ≥ 18 years old with advanced NSCLC, no remaining standard treatment options, measurable disease, Eastern Cooperative Oncology Group performance status of 0 to 2, and adequate organ function. Patients with NSCLC with CDKN2A alterations and no Rb mutations received palbociclib 125 mg orally once daily for 21 days, followed by 7 days off. Simon’s two-stage design was used with a primary study end point of objective response or stable disease (SD) of at least 16 weeks in duration. Secondary end points are progression-free survival (PFS), overall survival (OS), and safety.

RESULTS

Twenty-nine patients were enrolled from January 2017 to June 2018; two patients were not evaluable for response but were included in safety analyses. One patient with partial response and six patients with SD were observed, for a disease control rate of 31% (90% CI, 19% to 40%). Median PFS was 8.1 weeks (95% CI, 7.1 to 16.0 weeks), and median OS was 21.6 weeks (95% CI, 14.1 to 41.1 weeks). Eleven patients had at least 1 grade 3 or 4 adverse event (AE) or serious AE (SAE) possibly related to palbociclib (most common, cytopenias). Other AEs or SAEs possibly related to the treatment included anorexia, fatigue, febrile neutropenia, hypophosphatemia, sepsis, and vomiting.

CONCLUSION

Palbociclib monotherapy demonstrated evidence of modest antitumor activity in heavily pretreated patients with NSCLC with CDKN2A alterations. Additional investigation is necessary to confirm efficacy and utility of palbociclib in this population.

The Incidental Use of High-Dose Vitamin D3 in Pancreatic Cancer

Background: Pancreatic adenocarcinoma is associated with a very poor prognosis, with a 5 year survival of ∼7.2%. Vitamin D has long been evaluated for benefit as a protective agent and treatment for malignancies. Although cancer incidence and outcomes have been tied to vitamin D levels, there is no clear evidence that supplementation of vitamin D improves outcome in pancreatic cancer to date.

Case Presentation: We present a patient who errantly took supratherapeutic doses of vitamin D 50,000 U daily, achieving a serum 25(OH)D level of more than 150 mg/mL, with no appreciable side effects.

Conclusion: Her disease was stable for 8 months off of conventional treatment, although it is unclear whether this was related to vitamin D supplementation.

Squamous cell carcinoma of the oral cavity in nonsmoking women: a new and unusual complication of chemotherapy for recurrent ovarian cancer?

PURPOSE

To describe occurrences of oral squamous cell carcinoma (SCC) in patients who had received long-term pegylated liposomal doxorubicin (PLD) for ovarian cancer.

PATIENTS AND METHODS

In our cohort of patients on maintenance PLD for ovarian and related mullerian epithelial malignancies, we encountered two patients with invasive SCC of the oral cavity (one of them multifocal) and one with high-grade squamous dysplasia. Review of patients at our institution receiving PLD for recurrent ovarian cancer identified three additional patients. The duration of treatment, cumulative PLD dose, human papillomavirus (HPV) positivity, BRCA status, stage at diagnosis, outcome, and other characteristics are reviewed.

RESULTS

All five cases were nonsmokers with no known risk factors for HPV and four were negative for p16 expression. Four of the patients had known BRCA mutations whereas one tested negative. Cumulative doses of PLD were >1,600 mg/m2 given over 30-132 months. Three had SCCs staged as T1N0 oral tongue, alveolar ridge (gingival), and multifocal oral mucosa; one had a T2N0 oral tongue; and one had dysplasia. After excision, two were given radiation but recurred shortly thereafter; the others remain well and have had no further exposure to cytotoxic drugs, including PLD.

CONCLUSION

Awareness of this possible long-term complication during PLD treatment should enhance the likelihood of early detection of oral lesions in these patients. Decisions to continue maintenance PLD after complete response of the original cancer should perhaps consider the benefits of delaying ovarian cancer recurrence versus the possible risk for a secondary cancer.

Patterns of antibody response in humans to the anthrax vaccine adsorbed (AVA) primary (six-dose) series

The antibody profile during and after the six-dose primary vaccination series with anthrax vaccine adsorbed (AVA, Biothrax) was characterized in 86 human volunteers. Ninety-three percent of recipients developed IgG antibodies to Bacillus anthracis protective antigen (PA) after two doses, and 100% were seropositive after dose #3. Geometric mean concentrations (GMC) of IgG to PA measured before and after each dose were significantly lower after injection #3 (peak GMC=146.65 microg/mL, trough GMC=15.16 microg/mL) than after injections #4 (peak GMC=430.46 microg/mL, trough GMC=94.57 microg/mL), #5 (peak GMC=415.05 microg/mL, trough GMC=81.94 microg/mL), or #6 (peak GMC=401.16 microg/mL, trough GMC=96.19 microg/mL) (p<or=0.0001 for each); but not between injections #4 and #5, #5 and #6, or #4 and #6 (p>or=0.7923 for each). Decay rates for IgG to PA were significantly faster after injection #3 (half life [T1/2]=39.21 days) than after injections #4 (T1/2=72.03 days), #5 (T1/2=70.14 days), and #6 (T1/2=74.59 days) (p<or=0.0282 for each). Toxin neutralizing assay (TNA) antibody patterns generally paralleled those for IgG to PA. The 6-month dose in the AVA primary series appears to be critical in sustaining IgG to PA concentrations in a substantial proportion of recipients.

Long-term health effects of repeated exposure to multiple vaccines

The health of 155 former workers in a US military research program who had received multiple vaccines and 265 matched community controls was assessed. The study population was mostly male (83%) and elderly (median age, 69 years). Multiply immunized (MIP) subjects received vaccines and/or skin tests (median = 154) over a median of 17.3 years; interval from start of immunizations to survey completion was 15-55 years (mean = 43.1 years). MIP subjects characterized themselves as slightly less healthy than controls (P = 0.057). Fatigue (but no other symptom) was reported more frequently in the MIP group (P = 0.011), but was not associated with number of injections, number of vaccines, or time in program. No differences between MIP and control groups were seen for numerous self-reported medical conditions. Several statistically significant abnormalities were seen in clinical laboratory tests among MIP subjects, but none appeared to be clinically significant. A significant difference in frequency of monoclonal spikes and/or paraprotein peaks between MIP (12.5%) and control (4.5%) groups (RR = 2.7, P < 0.003) was observed; no associations with lifestyle, vaccine exposure, or medical conditions were found.

Anthrax vaccine: short-term safety experience in humans

Bacillus anthracis is the major terrorist and biological warfare agent of concern to civilian and military medical planners. The licensed anthrax vaccine, adsorbed (AVA) is believed to be an effective prophylactic medical countermeasure against this threat. Our objective in this report was to expand the safety database for this vaccine by assessing data on self-reported, short-term safety of AVA during more than 25 years of use, measured by local and systemic adverse events temporally associated with the administration of AVA. A minority of AVA recipients reported systemic and injection site reactions. Females reported a higher incidence of injection site and systemic adverse events than males. Data show a difference in incidence of local reactions between lots. A prospective, randomized, placebo-controlled study to actively examine reactogenicity is needed to more completely define the extent and nature of reactions associated with receipt of AVA in humans as well as to confirm the gender lot differences in local reaction rates.

Anthrax vaccine: increasing intervals between the first two doses enhances antibody response in humans

The influence of dosing interval on the human antibody response to anthrax vaccine adsorbed (AVA) was evaluated in two retrospective serological studies. In both studies, the interval between the first two doses was 2, 3 or 4 weeks. In the first study, banked sera were selected from 89 at-risk individuals at a mean time of 13 days after the second dose of vaccine. In the second study, banked sera were selected from 51 at-risk individuals at a mean time of 48 days following the first dose of AVA. In both studies, the geometric mean anti-protective antigen IgG antibody titer increased significantly as the interval between the two doses increased from 2 to 4 weeks (p=0.0005-0.029). In the first study, the seroconversion rate also increased as the interval between the first two doses increased (p=0. 0034). A prospective, randomized study has been completed and is being analyzed to confirm these findings.

Immunogenicity of an inactivated Rift Valley fever vaccine in humans: a 12-year experience

Rift Valley fever (RVF) virus causes serious and fatal disease in animals and man. To protect personnel who work with RVF virus in the laboratory, or troops who may be exposed to this virus, the US Army successfully developed an improved version of inactivated RVF vaccine, TSI-GSD-200. From early 1986 to late 1997, 598 at-risk workers at the US Army Medical Research Institute of Infectious Diseases (USAMRIID) were vaccinated as part of an occupational safety and health program. The subjects of this study received three subcutaneous doses (0, 7 and 28 days) of 0.5 ml of TSI-GSD-200. A total of 540 vaccinees (90.3%) initially responded (group A) with an 80% plaque-reduction neutralization antibody titer (PRNT80) of > or =1:40; whereas 58 subjects (9.7%) were initial nonresponders (group B) failing to achieve this titer. Volunteers who either failed to respond or who achieved a titer of > or =1:40 but whose titer waned below 1:40 were boosted 1-4 times with the same vaccine. Among 247 group A subjects who received the first recall injection, 242 (98%) were successfully boosted, achieving a PRNT80 > or =1:40. Thirty-three of 44 (75%) initial nonresponders were converted to responder status after the first booster, which is a lower rate than that of group A (P < 0.001). After the primary series and the first booster, Kaplan-Meier analysis showed 50% probability of group A members maintaining a titer of > or =1:40 for approximately eight years; whereas group B had a 50% probability of maintaining a titer for only 204 days. Group A immune response rates to boosts 1-4 ranged from 87 to 100% with geometric mean titers (GMTs) ranging from 80 to 916. Boosts 1-4 immune response rates of group B volunteers ranged from 67 to 79% with GMTs ranging from 90 to 177. Minor side effects to TSI-GSD-200 were noted in 2.7% of all vaccinees after primaries and 3.5% of all vaccinees who had primaries and up to four boosters. We conclude that the use of TSI-GSD-200 is safe and provides good long-term immunity in humans when the primary series and one boost are administered.

Long-term duration of detectable neutralizing antibodies after administration of live-attenuated VEE vaccine and following booster vaccination with inactivated VEE vaccine

The US Army successfully developed a live-attenuated Venezuelan Equine Encephalitis (VEE) vaccine, TC-83, in 1961, and subsequently developed a formalin-inactivated vaccine, C-84, in 1974. Initial evaluation of both vaccines was promising, but no long-term safety and immunogenicity data have been reported. This study is the first analysis of the long-term safety and immunogenicity of TC-83 and C-84. From January 1976 to December 1990, 821 laboratory workers at the USAMRIID were vaccinated with a single 0.5 ml subcutaneous (s.c.) dose of TC-83; 128 were boosted with a single 0.5 ml s.c. dose of C-84. Eighty-two per cent of vaccinees responded to TC-83 with an 80% plaque reduction neutralization titer (PRNT80) of > or = 1:20. Minor side-effects were noted in 23% of vaccinees. No long-term sequelae were recorded. Kaplan-Meier analysis showed a 60% probability of vaccinees maintaining a PRNT80 of > or = 1:20 for 5.5-8 years. C-84 was given to two groups: 76 initial nonresponders to TC-83, Group A, and 52 initial responders to TC-83 whose PRNT80 became < 1:20 over time, Group B. C-84 successfully boosted 76% of Group A and 100% of Group B to a PRNT80 > or = 1:20 Kaplan-Meier analysis showed 100% probability of Group B members maintaining a titer of > or = 1:20 for the duration of follow-up, which, in some cases, exceeded 10 years; while Group A had only a 60% probability of maintaining a titer for 1-2 years. Only minor local reactions to C-84 were noted in 6.3% of vaccinees. We conclude that, although TC-83 is reactogenic, when administered as the primary vaccine and C-84 is administered as a boost, these vaccines provide good long-term immunity and are safe in humans. However, a single dose vaccine that is more immunogenic and less reactogenic is needed.

Reduced survival of adult Culex pipiens infected with Rift Valley fever virus

The effect of Rift Valley fever (RVF) viral infection on the survival of female Culex pipiens was examined. In 3 experiments in which mosquitoes ingested RVF virus, there was a 44% decrease in survival to days 14-16 for transmitting vs. nontransmitting mosquitoes, and a 48% decrease in survival for individuals with disseminated vs. nondisseminated infections. These results were corroborated by other experiments in which survival of mosquitoes intrathoracically inoculated with RVF virus was compared with that of those inoculated with diluent. In both the per os and inoculation tests, uninfected mosquitoes survived significantly longer than infected mosquitoes. Even though mosquitoes with disseminated infections had a lower survival rate than did uninfected mosquitoes, dissemination and transmission rates were similar at days 7 and 14-18 after the infectious bloodmeal. This suggests that nondisseminated individuals were developing disseminated infections and becoming capable of transmitting virus between days 7 and 14-18 at approximately the same rate older transmitters were dying. The decreased survival associated with RVF viral infection should be considered in predictive models of this disease.