Ellen Bolotin

Bone marrow transplantation (BMT) is followed by a period of profound immune deficiency, during which new T lymphocytes are generated from either stem cells or immature thymic progenitors. Interleukin-7 (IL-7) induces proliferation and differentiation of immature thymocytes. We examined whether the in vivo administration of IL-7 to mice receiving BMT would alter thymic reconstitution. Lethally irradiated C57BL/6 mice received syngeneic BMT, followed by either IL-7 or placebo from days 5 to 18 post-BMT. At day 28, BMT recipients that had not received IL-7 had profound thymic hypoplasia (< 5% of normal), with relative increases in the numbers of immature thymocytes, decreased numbers of mature peripheral (splenic) T lymphocytes, and severely impaired T- and B-cell function. In contrast, transplanted mice treated with IL-7 had normalization of thymic cellularity, with normal proportions of thymic subsets and T-cell receptor beta variable gene (TCRV beta) usage, normal numbers of peripheral CD4+ T lymphocytes, and improved antigen-specific T- and B-cell function. In the BMT-IL-7 mice, there was an eightfold increase in the number of immature CD3-CD4-CD8- thymocytes in G2-M of the cell cycle, indicating that restoration of thymic cellularity was due to enhanced proliferation of immature thymic progenitors. Similar effects following IL-7 administration were also observed when donor bone marrow was depleted of mature T lymphocytes, indicating that IL-7 administration affected immature hematopoietic progenitors. IL-7 promotes thymic reconstitution after BMT, and may be useful in preventing post-BMT immune deficiency.

PURPOSE Telisotuzumab vedotin (Teliso-V) is a c-Met–directed antibody-drug conjugate with a monomethyl auristatin E cytotoxic payload. The phase II LUMINOSITY trial (ClinicalTrials.gov identifier: NCT03539536 ) aimed to identify the optimal c-Met protein–overexpressing non–small cell lung cancer (NSCLC) population for treatment with Teliso-V (stage I) and expand the selected group for efficacy evaluation (stage II). Stage II enrolled patients with nonsquamous epidermal growth factor receptor ( EGFR )-wildtype NSCLC. METHODS Eligible patients had locally advanced/metastatic c-Met protein–overexpressing NSCLC and ≤2 previous lines of therapy (including ≤1 line of systemic chemotherapy). c-Met protein overexpression in nonsquamous EGFR -wildtype NSCLC was defined as ≥25% tumor cells with 3+ staining (high [≥50% 3+]; intermediate [≥25%–&lt;50%]). Teliso-V was administered at 1.9 mg/kg once every 2 weeks. The primary end point was overall response rate (ORR) by independent central review. RESULTS In total, 172 patients with nonsquamous EGFR -wildtype NSCLC received Teliso-V in stages I and II. ORR was 28.6% (95% CI, 21.7 to 36.2; c-Met high, 34.6% [95% CI, 24.2 to 46.2]; c-Met intermediate, 22.9% [95% CI, 14.4 to 33.4]). The median duration of response was 8.3 months (95% CI, 5.6 to 11.3; c-Met high, 9.0 [95% CI, 4.2 to 13.0]; c-Met intermediate: 7.2 [95% CI, 5.3 to 11.5]). The median overall survival was 14.5 months (95% CI, 9.9 to 16.6; c-Met high, 14.6 [95% CI, 9.2 to 25.6]; c-Met intermediate, 14.2 [95% CI, 9.6 to 16.6]). The median progression-free survival was 5.7 months (95% CI, 4.6 to 6.9; c-Met high, 5.5 [95% CI, 4.1 to 8.3]; c-Met intermediate: 6.0 [95% CI, 4.5 to 8.1]). Most common any-grade treatment-related adverse events (AEs) were peripheral sensory neuropathy (30%), peripheral edema (16%), and fatigue (14%); the most common grade ≥3 AE was peripheral sensory neuropathy (7%). CONCLUSION Teliso-V was associated with durable responses in c-Met protein–overexpressing nonsquamous EGFR -wildtype NSCLC, especially in those with high c-Met. AEs were generally manageable.

In the era of cytomegalovirus (CMV)-preemptive therapy, it is unclear whether CMV serostatus of donor or recipient affects outcome of allogeneic hematopoietic stem cell transplantation (HSCT) among children with leukemia. To investigate, consecutive patients aged 0-18 who underwent primary HSCT for acute leukemia in 1997-2007 (HLA-matched sibling or unrelated donor, myeloablative conditioning, unmanipulated bone marrow or peripheral blood, preemptive therapy, no CMV prophylaxis) were followed retrospectively through January 2008. Treatment failure (relapse or death) was analyzed using survival-based proportional hazards regression. Competing risks (relapse and nonrelapse mortality, NRM) were analyzed using generalized linear models of cumulative incidence-based proportional hazards. Excluding 4 (2.8%) patients lacking serostatus of donor or recipient, there were 140 subjects, of whom 50 relapsed and 24 died in remission. Pretransplant CMV seroprevalence was 55.7% in recipients, 57.1% in donors. Thirty-five (25.0%) grafts were from seronegative donor to seronegative recipient (D-/R-). On univariate analysis, D-/R- grafts were associated with shorter relapse-free survival (RFS) than other grafts (median 1.06 versus 3.15 years, P < .05). Adjusted for donor type, diagnosis, disease stage, recipient and donor age, female-to-male graft, graft source, and year, D-/R- graft was associated with relapse (hazards ratio 3.15, 95% confidence interval 1.46-6.76) and treatment failure (2.45, 1.46-4.12) but not significantly with NRM (2.00, 0.44-9.09). In the current era, children who undergo allogeneic HSCT for acute leukemia have reduced risk of relapse and superior RFS when recipient and/or donor is CMV-seropositive before transplantation. However, no net improvement in RFS would be gained from substituting seropositive unrelated for seronegative sibling donors.

9016 Background: Teliso-V is an antibody-drug conjugate composed of a c-Met antibody (ABT-700) and a microtubule inhibitor (monomethyl auristatin E). The phase 2 M14-239 trial (LUMINOSITY, NCT03539536) aims to identify the c-Met OE NSCLC populations best suited to Teliso-V (Stage 1) and expand selected groups for further evaluation of efficacy (Stage 2). In Stage 1, pts were enrolled into cohorts defined by histopathology (non-squamous [NSQ] or squamous [SQ]) and EGFR mutation status (mutant or wild type [WT]); NSQ cohorts were further divided in groups on the basis of c-Met expression (high or intermediate). Updated data from the fourth interim analysis (IA4) are presented. Methods: Pts had locally advanced/metastatic NSCLC, ≤2 prior lines of systemic therapy, ≤1 line of chemotherapy, and tumors that were c-Met OE by central immunohistochemistry (IHC; Ventana; Tucson, AZ). c-Met OE was defined for the NSQ cohort as ≥25% 3+ by IHC (high, ≥50% 3+; intermediate, 25 to &lt;50% 3+) and for the SQ cohort as ≥75% 1+ by IHC. The planned enrollment was up to approximately 150 pts in Stage 1 and 160 pts in Stage 2. Teliso-V was dosed at 1.9 mg/kg IV Q2W. The primary endpoint is objective response rate (ORR) by independent central review. Secondary endpoints include duration of response (DOR). Results: As of data cutoff (27 May 2021), 136 pts were treated with Teliso-V; 122 were evaluable for ORR. ORR was 36.5% in the NSQ EGFR WT cohort (52.2% in c-Met high group and 24.1% in c-Met intermediate group), but was modest in the NSQ EGFR mutant and SQ cohorts. Efficacy data in groups/cohorts are in the Table. The most common any-grade adverse events (AEs) were peripheral sensory neuropathy (25.0%), nausea (22.1%), and hypoalbuminemia (20.6%). Grade 5 AEs considered possibly related to Teliso-V occurred in 2 pts (sudden death and pneumonitis in 1 pt each in the SQ cohort). Conclusions: Teliso-V demonstrated a promising ORR in pts with previously treated c-Met OE NSQ EGFR WT NSCLC; this cohort is currently expanding in Stage 2. ORR was modest in the cohorts of pts with c-Met OE NSQ EGFR mutant NSCLC and with c-Met OE SQ NSCLC; both cohorts have now met the protocol-specified stopping criteria and are no longer enrolling. The safety profile observed was consistent with IA3. Clinical trial information: NCT03539536. [Table: see text]