Combination therapy with Olaratumab/doxorubicin in advanced or metastatic soft tissue sarcoma -a single-Centre experience

Results of an Open-label, Phase Ia/b Study of Pembrolizumab plus Olaratumab in Patients with Unresectable, Locally Advanced, or Metastatic Soft-Tissue Sarcoma

PURPOSE

The study evaluated safety and efficacy of olaratumab + pembrolizumab in patients with unresectable locally advanced/metastatic soft-tissue sarcoma (STS) with disease progression on standard treatment.

PATIENTS AND METHODS

This was open-label, multicenter, nonrandomized, phase Ia/Ib dose-escalation study followed by cohort expansion (olaratumab + pembrolizumab intravenous infusion). Primary objectives were safety and tolerability.

RESULTS

The majority of patients enrolled (n = 41) were female [phase Ia: 9 of 13, phase Ib/dose-expansion cohort (DEC), 17 of 28], aged < 65 years. In phases Ia and Ib, 13 and 26 patients received prior systemic therapy, respectively. Patients received olaratumab 15 mg/kg (phase Ia; cohort 1) or 20 mg/kg (phase Ia; cohort 2 and phase Ib) and pembrolizumab 200 mg (phase Ia/Ib). The median (Q1-Q3) duration of therapy (olaratumab) was 6.0 (3.0-11.9; cohort 1), 14.4 (12.4-20.9; cohort 2), and 14.0 (6.0-21.8) weeks (DEC). No dose-limiting toxicities and few grade ≥ 3 treatment-emergent adverse events [TEAE; 15 mg/kg: 2 (increased lipase); 20 mg/kg: 1 (increased lipase), 1 (colitis), 2 (diarrhea), 3 (anemia)] were reported. Two TEAEs (increased lipase) were related to study discontinuations. Twenty-one patients reported mild (grade ≤ 2) TEAEs [phase Ia, disease control rate (DCR):14.3% (1/7, cohort 1); 66.7% (4/6, cohort 2); no responses were reported; phase Ib, DCR: 53.6% (15/28); objective response rate: 21.4% (6/28; RECIST and irRECIST criteria)]. No response was observed in patients with programmed death ligand-1-positive tumors.

CONCLUSIONS

Antitumor activity was observed in some patients in DEC, and combination was well tolerated with manageable safety profile. Further studies are warranted to evaluate the efficacy and mechanistic impact of platelet-derived growth factor receptor inhibitors with immune checkpoint modulator coadministration.

Olaratumab's failure in soft tissue sarcoma

Soft tissue sarcomas remain one of the rarest malignancies with numerous subtypes that go undiagnosed. The PDGFRα antagonist Olaratumab (Lartruvo) was withdrawn from the market due to disappointing findings in the phase III studies. We share our experience with this medication in a tertiary care center in the Middle East and North Africa region. Monitor the effect of Olaratumab on sarcomas when it was used prior to its withdrawal, and compare our findings with the literature. We performed a retrospective analysis of adult patients with advanced-/metastatic soft tissue sarcomas treated with at least two cycles of Olaratumab at a tertiary care center in Lebanon during the period from January 1, 2017 to December 31, 2018. Fifteen patients were included in the study. The mean age was 49 with a range of 26–75 years. The median duration of the use of Olaratumab was 21.3 months with a range of 7.3–37 months. The average number of number of cycles received per patient was four. Five patients were deceased. Median PFS was 7.87 months (95% CI 5.28–10.45), and mean OS was 12.26 months (95% CI 8.47–16.05) Median OS was 9.8 months (95% CI 6.07–13.53). Olaratumab has been withdrawn from the market, and it is currently being investigated as part of the phase II ANNOUNCE 2 trial. Our experience from a tertiary care center shows results similar to those reported in the literature. The immunogenicity and heterogeneity of soft tissue sarcomas pose a challenge to the treatment of soft tissue sarcomas, but they also allow a wide array of possible management solutions.

GZ17-6.02 and Doxorubicin Interact to Kill Sarcoma Cells via Autophagy and Death Receptor Signaling

GZ17-6.02 (602) is presently under phase I clinical evaluation (NCT03775525). We defined the mechanisms by which it interacted with a standard of care therapeutic doxorubicin to kill sarcoma cells. Doxorubicin and 602 interacted to rapidly activate ATM and c-MET, inactivate mTOR, AKT, and p70 S6K, enhance the expression of Beclin1 and reduce the levels of K-RAS and N-RAS. This was followed later by the drugs interacting to reduce expression of MCL-1, BCL-XL, and HDAC6. Knock down of ATM prevented the drugs alone or in combination inactivating mTOR or activating ULK1. Knock down of c-MET significantly enhanced [doxorubicin + 602] lethality. Knock down of ATM and to a greater extent ULK1, Beclin1, or ATG5 significantly reduced killing by 602 alone or when combined with doxorubicin. Expression of an activated mTOR mutant suppressed killing, autophagosome formation and prevented autophagic flux. In the absence of Beclin1, knock down of CD95, or FADD, or over-expression of c-FLIP-s or BCL-XL abolished tumor cell killing. We conclude that 602 and doxorubicin interact to increase autophagosome formation and autophagic flux as well as causing elevated death receptor signaling resulting in mitochondrial dysfunction and tumor cell death.