The principles governing evolution of tumors exposed to targeted therapy are poorly understood. Here we modeled the selection and propagation of BRAF amplification (BRAFamp) in patient-derived tumor xenografts (PDX) treated with a direct ERK inhibitor, alone or in combination with other pathway inhibitors. Single cell sequencing and multiplex-fluorescence in situ hybridization mapped the emergence of extra-chromosomal amplification in parallel evolutionary tracts, arising in the same tumor shortly after treatment. The evolutionary selection of BRAFamp is determined by the fitness threshold, the barrier subclonal populations need to overcome to regain fitness in the presence of therapy. This differed for ERK signaling inhibitors, suggesting that sequential monotherapy is ineffective and selects for a progressively higher BRAF copy number. Concurrent targeting of RAF, MEK and ERK, however, imposes a sufficiently high fitness threshold to prevent the propagation of subclones with high-level amplification. Administered on an intermittent schedule, this treatment inhibited tumor growth in 11/11-lung cancer and melanoma PDX without apparent toxicity in mice. Thus, gene amplification can be acquired and expanded through parallel evolution, enabling tumors to adapt while maintaining their intratumoral heterogeneity. Treatments that impose the highest fitness threshold will likely prevent the evolution of resistance-causing alterations and merit testing in patients.

One course of adjuvant BEP reduces the risk of relapse by approximately 90% in both VASC+ and VASC- CS1 NSGCT, and may be a new option as initial treatment for all CS1 NSGCT. One course of adjuvant BEP for VASC+ CS1 reduces the total burden of chemotherapy compared with surveillance or two courses of BEP. SWENOTECA currently recommends one course of BEP as standard treatment of VASC+ CS1 NSGCT, whereas both surveillance and one course of BEP are options for VASC- CS1 NSGCT.

Metastatic uveal melanoma is less well understood than its primary counterpart, has a distinct biology compared to skin melanoma, and lacks effective treatments. Here we genomically profile metastatic tumors and infiltrating lymphocytes. BAP1 alterations are overrepresented and found in 29/32 of cases. Reintroducing a functional BAP1 allele into a deficient patient-derived cell line, reveals a broad shift towards a transcriptomic subtype previously associated with better prognosis of the primary disease. One outlier tumor has a high mutational burden associated with UV-damage. CDKN2A deletions also occur, which are rarely present in primaries. A focused knockdown screen is used to investigate overexpressed genes associated withcopy number gains. Tumor-infiltrating lymphocytes are in several cases found tumor-reactive, but expression of the immune checkpoint receptors TIM-3, TIGIT and LAG3 is also abundant. This study represents the largest whole-genome analysis of uveal melanoma to date, and presents an updated view of the metastatic disease.

An international, population-based treatment protocol for testicular seminoma is feasible with excellent results. Surveillance remains a good option for CS1 patients. No factors predicted relapse in CS1 patients on surveillance. Despite resulting in a lower rate of relapse than with adjuvant carboplatin, adjuvant radiotherapy has been abandoned in the Swedish and Norwegian Testicular Cancer Project (SWENOTECA) as a recommended treatment option because of concerns of induction of secondary cancers. The higher number of relapses in radiotherapy-treated CS2A patients when compared with chemotherapy-treated CS2A/B patients is of concern. Late toxicity of cisplatin-based chemotherapy versus radiotherapy must be considered in CS2A patients.